60429_bicho seda takayana

IHDI .I. Ui:.3:WJ •• lClI

.G l:[OLJ IlI'U .ILl, l' 111 U ~ 1'1, J'JEN DElHI ~

(~rD,l1t in Aid [or Scientifjc Research.

Ministry of Education

SILKWORM GENETICS

jLLUSTI~ATED

SC4::!9

r 111111 m 11~lllll' ~m 11111111 fARI

SILKWORM GENETICS

ILLUSTRATED

BY

Tadao YOKOYAMA, D. Agr.

Director (~r llie S'rricu/lltml E\j)erimelll S'lation.

Millislry of i\gricil/lurc lind Foresl;y,

81t.'!:illmni-lm, 'l'61<),(), ]aj)({/1

Japan Socidy for the Promotion of Science

J!J~!J

Published by Japan Society for Promotion

of Science, Ueno Park, TiJkyo, Japan

erin/cll in l1cratd ill):!;, Co" Ltd" ,'-,'/li/l(/Ilra,

]()/~y(j, lllj)(lil

Jj 2

7 9

13 14 15

10 11

16 17

I -..

6

12

18

Silkworm PattcrilS

1. Bombyx i/I{{/u!ariIlCl

2. normal patterll (-I-I! II-O.O) 3. hlack (I,ll II-(J.O) 1). moricalld (/,11 II-D.O) r,. sl rilled (j,s 11-0.0)

G. ~triJlcd ami dominanl c1\m:ubk. (1)8 II-lUI, I-a IX-O.O)

7. ll1ul1i1unar (L IV-O.O) 8. lllllltilllJ1ar and speckled

(L IV-1I.0, SjJ,; IV-33.l) ~. tluail (q VII-O,O)

10. e1il \1l" blaL:k (bd IX-I).7) 11. knl1hbed and ursa

(T\ XI-O.O, [J Xl V-S.O) 1~. (liny en; XIV-lO.?) 1:1. stollY (st VIll-±5.7) H Kins!lirYli translucenl «(}I~ V-'l.7) Iii. icmon (fant H1-22.:-1) Iii. red blood (rb)

17. l.cbra fueled (2"f JlI-D.O) 18. hereditary mosaic

(normal amI ~ehra)

Preface

The International Genetics Symposia were held in Tokyo and Kyoto £ro111 the 6th to the 12th of September, 1956. The organizing committee of the Symposia, Dr. H. KIHARA presiding, planned to exhibit genetical objects characteristic of Japan. The Exhibits Subcommittee, Dr. Y. NOGUCHI presiding, was organized to bring together 8 working groups, each group under the leadership of the person designated in the parentheses below:

1. Japanese Morning Glory (Dr. Yo TAKEN AKA) 2. The Biggest and the Longest Radishes in the World (Dr. Ichizo

NISHIYAMA) 3. Wheat and its Relatives (Dr. Hitoshi KIHARA) '1. Rice (Dr. Toshitaro MORINAGA) 5. The Silkworm (Dr. Taelao YOKOYAMA) G. The Long-tailed Fowl (Dr. Kiyoshi MAScTJ) 7. The Gold-fish (Dr. Yoshiichi MATSUI) 8. Olel Documents (Dr. Yosito SINOTO)

The purpose of the silkworm exhibition was to enable the visitors to understand as well and as widely as possible the silkworm genetics and the raw silk industry in Japan. All silkworm geneticists were asked to participate in it. The exhibition was extended so as to include mulberry breeding, pathogenic micro-organisms attacking silkworms and mulberry trees, and wild silkworms, because it was thought that these would bring a better understanding of the whole industry.

Special efforts were made by the research group under Dr. Y. TANAKA 'to complete all chromosome maps on the silkworm in time for the exhibition with the result th;;1.t theYJ found twenty-eight presumptive linkage groups of genes corresponding to the haploid number of the silkworm chromosomes. These efforts were aided financially by the Ministry of Education.

No special emphasis was put on any particular field of silkworm genetics. However, many visitors inspected with great interest such exhibitions as 80 different kinds of Jiving larvae; silkworms of artificially induced mutation, which ieed on various plants other than mulberry leaf; theory and practical application of sex-determination; developmental genetics advanced by utilizing various mutants; various hormonal studies in relation to the development; and studies on the coloring substances of silkworms and cocoons.

The Silkworm Exhibition was opened on the 8th of September, 1956, and there were 200 visitors, a few of whom remained there for several hours eagerly looking at and discllssing the exhibitions. Not only the"e specialists but also many geneticists of recent acquaintance ad vised us to publish the pictnres and tables exhibited. Their advice is now to be realized by the co-

ii Preface

operation of the members of the working group aided by the grant of the Ministry of Education.

All members of the working group were co-orc1inated in every aspect of

the task. Especially Dr. S. SIIIMlZU, Dr. M. HARIZl.mA, Mr. T. nmOIl!( and Mr. T. TAKAMI supported the group. Painstaking efforts by all of them were

highly appreciated. Dr. H. KrnARA, Chairman of the Organil,ing Committee,

Dr. Y. TANAKA, Chairman of the Lecture Subcommittee, Dr. Y. NOGllCH[,

Chairman of the Exhibition Subcommittee, gave us valuable advice, encourage· ment and help whenever needed. We were also aided by thc Science Council of Japan, the Ministry of Education and the Ministry of Agriculturc and Forestry. Mr. H. MIYAYAMA of the Ministry of Eclucalioll gave m; very woeful advice and aided us in many ways in the pUblication of this book. On behalf of the working .lSroup of the Silkworm Exhibition, I express here my hearty thanko; to all pe1'sons and organizations mentioned ahove.

My sincere gratitude also goes to Dr. Ycniito SINOTO or the International Christian University f()r his kincl help as well as to Mes:H.·s. Edward J\ In:n~ and Yasuyuki OWADA for correcting the English manuscripts.

April 29, 1%8 Tac!ao Y OKOY.A.MA Leader, The Working Group of the Silkworm Exhibition

Members of the Worldng Group of the Silkworm Exhihition

Mr. AIDA, Fumio Dr. AOI<I, Kiyoshi Dr. Aln.JGA, Hisao Mr. ClIIKusm, Baruo Mr. HA.MAllA, Shigeyoshi Mr. HARADA, Chuji Dr. HAlHZUI(A, Masaki Dr. HASIMOTO, HarLlo Mr. EmOllE, Tatsumichi Dr. hIKAWA, Nobuka7.ll Dr. KOGURE, Makita

Dr. Kuw ANA, Zyuiti Dr. SASAI{f, Shizuka Dr. SIlIMIZU, Shigeru Dr. TAZIMA, Yataro

Mr. TAI{AMI, Takeo Mr. TAKASAKI, Tsuneo Dr. YOKOYAMA, Tac1ao

St:ricultural Experiment Stati()ll, M. A. F.

Tokyo Univen:ity Kyushu University

Do.

Sericulturhl Experiment Stat ion, M. A. F. Do. Do. Du. Do. Do.

Tokyo University of Agriculture amI Textile Industry Sericllitural Experiment Station, M. A. F.

Do. Do.

Silk Science Research I nstiittle (Now, National Institute of Gl'neliu;) Sericu [tural Experiment Stalion; M. 1\. F.

Do. Do, (Leader of the Gruup)

Silkworm Genetics Illustrated

By

Tadao YOKOYAMA

Contents Pages

Introduction ..................................................................... '" .... ..... 1 I. Life History (including the Silk Secretion) '" ............ ... ... .......... ..... 4

II. Hereditary Traits and Chromosome Maps .................................... 12 III. Cytology and Reproduction...... ... ......... ..... .... ... ...... ......... ............... 40 IV. Sex Detennillation ........................................................................ 44 V. Induced Mutations and the Practical Application.... .......... ............. 52

VI. Mosaics .............................. '" ...... ...... ....................... ............ ..... .. 66 VII. Developmental Genetics ............................................................... 73

VIII. Physiological Genetics .................................................................. 91 IX. Biochenlical Genetics ..................................................................... 108 X. Breeding (including Heterosis) ............................... : ...................... 138

XI. Relation between the Silkworm Races and the Pathogenicity of Muscardines ................................................................................. 157

XII. Wild Silkworms ........................................................................... 161 XIII. Genetics of Mulberry (including Food Plants of the Silkworm Other

than Mulberry) .............................................................................. 165 Literature .................................................................................... 183

Silkworm· Geneticfl IIlustrated 1

Introduction

The silkworm has been reared in Japan for mote than 1000 years. Since the latter half of the 19th century raw silk has become one of the most important export goods of Japan. ~ericult1Jre has developed into an important, representative industry of this country.

Owing to the governmental encouragement for the advance of scientific research and extension of techniques, remarkable and u~eful research results have been obtained, contributing much to higher development of the industry. The most important contribution among l11any is the adoption of hybrid silkworm.

The Sericultural Experiment Station of the Ministry of Agriculture and Forestry was established in 1911. Toyama of the station had already· been engaged in genetical study of the silkworm since about 1900, and published the results of his research in 1900. In thc course of his research hc recognized the heterosis. Following his advice, the government had decided to encourage hybrid silkworm instead of aboriginal pure races and started the distribution of hybrid eggs in 1'914. The rearing of a vigorous and productive hybrid silkworm stabilized the crop of the summer and autumn silkworm culture. The production of silk from a unit area of mulberry field remarkably increased by raising two or three crops instead of usual one spring crop from the same field.

Silkworm genetics in Japan started and has developed in connection with silkworm breeding, gradually enlarging the domain of its research sphere. Keeping pace with the advancement of genetics, the related sciences in sericulture have also made progress thus contributing to the development of the industry. The industry on the other hand presented many scientific problems to be solved, which gave the opportunity for scientific discoveries. In such a way the industry and the science aided mutually in the course of their own advances, thus the largest country of the silk industry made itself also the largest country in the study of silkworm genetics.

There are about GO recognized scientists in Japan in the field of genetics and breeding of silkworm, the papers published from 1945 to 1955 amounting to 590. Silkworm genetics in Japan owes much for its progress to the sericultural industry, but the silkworm itself is considered to be a very appropriate animal for the study of genetics, making possible the advance in research in various aspects of the field. In the connection the following points may merit special attention:

1) There are numerous heritable traits in the silkworm and the number of such traits can be increased comparatively easily by the induction of arti· . ticial mutations.

2 T. Yokoyama

2) Fi ve to six gcneratiOllE> may he repeated in a year by artiftcial hatch

ing of eggs, and the larvae thereof are easy to rear.

:~) The number of eggs laid by one moth is about 500 and they are

numerous enough to justify statistical treatment of the results in genetical

stuely. 4) The related sciences to genetics such as morphology, physiology or

oecology have attained a high level of achievement, and the adjustment of

developlllent or rearing is easy. Therefore silkworm is a very convenient

animal to follow the course of development of traits contl'olkd by genes.

5) Also it is easy to obtain large number of animals of uniform charac

teristics.

For this exhibition an attempt is made to reveal as much knowledge of

silkworm genetics as possible, which has been accumulated in [l\lout: [iO years

by TOYAMA, TANAKA and their followers. It will be worthwhile to give lwre an outline of the raw silk incluHtqt of

Japan. The amount of raw silk produced in HlG(i hy 21 countries in the world is

28,808.4 metric ton~" i. e. 0.2% of the Lotal textile libel'S. Japan product'S about 63% of the total output of raw silk, China 15;)6, Russia H;),;, rUdy 4.2%, Hud

India 4%. Silkworms arc reared in every pre.i'ecttlrc in Japan, especially thri· ving in the middle region. There me about 7(j.1,OO() scricultural farmers who grow about 193,000 hectars of mulberry, the ligures corre:->])oncling Lo 12.596 of the total farmers and :l2~;; of the total arabl(.~ lanel respectively.

The income from sericulture is ahout Hl% of the total household inl'(nne in the serlcultural. farmers anel ahout 4;)6 of the toial agricultural income of

Japan. During World War 1[, tIll' sl'riculture dccrl'<I:->ecl to the I()we~;t levels, hut

since the end of the war it has gradually heen n~cllvering. In 1~)G(i it increased

to 2.:1 times of the war-time lowest level.

The raw silk produced in Japan amounts to 181hou~al1d metric t()ns, about

two thirds of which is consumed in the country and the n'st is l'xported as raw

silk or as silk fabrics. The situation of silk among export goods was so important in the past as amollnting to 1]8.l);i;; of the total export in 1022, but it:

is only :1,4% in 1957, sUll it remaining one of the lllost important agTicl.llturai

export goods in Japan.

Exported silk was used lTIoslly for hosiery befoi"e, but now j~ replaced by

nylon. Silk is now more used for textile fabrics. Silk has many attribute~

nnparallelly good for high quality textiles such as ela~ticity, smoothnesH, lightness, dyeing ability, luster, draping-quality and hyg'ienic properties. On

the other hand there are some undesirable aspects in silk such as browl1ing and fragility by weathering and lousiness. To remove the defect of browning

Silkworm Genetics Illustwtcd 3

and fragility chemical studies are going to be carried (Jut, while lousiness problem has. been partly solved by breeding good varit;;ties of silkworm and by a new processing method.

T. Yokoyama

I. Life History (including the Sill, Secretion)

U~ual1y in Japan the silkworm eggs hatch from the end of April to the

beginning; or May under natural conditions. If the eggs which passed the . diapawic are kept at the temperature of 2:~o_25°C., they hatch in lO·-14 days,

and the incubation period of the nOll-hibernating eggs is of about the same

duration. The nl'wly hatched larvae are black of ahout :l111m. in length, about OAS

mg. in weight. These worms spin e(J('nons in 2fi clays when reared al 2fiOC. alter molting ,1 times.

The larvae grow to thp maximum weight in one or one anel a halt clay

he fore spinning cocoons, the body weight heing about 12,000 times of the

newly hatched worm. When the larvae have grown tn the extent lhat they are reacly to spin

cocoons, they are called ripe or "mat.ure ". In the mature larva, silkg-Ianc1s are so large that they Ol'CU[JY ahou! ,10% of the hody weight. ,Farmers llsualIy put the lllature worms in a Rpinning I1CSt, sllch procedure being. called

"mounting ". It takes about a week after mounting [or tlw larvae to pupate,

and 8 to lS days more for emergence of moth~, which come out of the cocoons

softening the cocoon 1:;he11 by an alkaline fluid secreted in the crop. The moths

come out mmally in the morning, and soon after that male '.llld female moths mate. About !lOO eggs arc laid by u female moth hy the IWXt morning.

If the artificial hatching treatment is applied to tlw hiilc'rnating eggs in about 20 hours after lnying, the eggs hatch in alJlllll III rlays afte], the trc'alme nt, thus enabling llw repetition of generations. One gC'l1eration, I'roTll cg.l'; to

egg, is completed in ahout GO clays including the incuhation period. For t'coJlomical reason, the silkworms are. reared usually t!tr(_~e times a ye'ar in .lapan, hut

fr0111 gl'llctical point of view, it is possible to repeat six gl'IWratiolls a year utilizing; a warm place like Okinawa where they get llIull1l'rry leave'S in winter .

.. The silk substance is secreted hy a pair of silkgJands each orig·inating

from the invagination of epithelial cells in the embryonic labial segment. The silkgland is divided into three different parts, anterior, middle anc! posterior.

The silk substance is a protein called fibroin of linearly arrang'ed amino aciel

molecules consisting· of glycine, alanine, tyrosine, serine and B others, which

is secreted in the posterior part of the gland and accumulated in the middle

part and spun out from spinneret in the labial segment. The fihroin which is a viscous gelatinous substance in the gland becomes fibro1l3 when spun out.

The fibroin fiber is coated with a "gum" called sericin which is secreted in

the middle part of the silkgland. Recently it was found by M. SIUMI~U (19GS)

that cellulose substance is usually secreted in the middle part of the silkglancl.

Silkworm Genetics III Llstra(~rl 5

I-I. Life history of the silkworm The exhibition displays living silkworms of all instars together with

pupae, moths and hibernating and non·hibernating eggs as well as a schcmaUc expression of the life history.

I-I Life history uf the silkworm ,.

Diapau~e & Winterir,g :i i

4-9 mOI1Ii1s

.~-.... / Terminati011 of ~

I diapausc can I", '\

IrC~(l/;ltCd tlY cold .tomlte i.

A ./' Artificial Hatching~ .. ~ Il'ltchinl1

~~_~"~~(Incu_b~ltion2 '" %//~Brt16hing diupausing egg Eggs can be stored /' ~

for about 90 days before. 1st instar . artiliclal treatment at / \ 3"'""4 da}'$

Egg La;nng , " '~ low temperature 9-i2 <laysilncubation) 1&./ I-Mellt

_~-~.-0/ ~~lar '- ~-~ nan.d,apause eGg ? 0 I '''OJ' I.'~~·_- ~-0 ",I" II-Molt

moth Temp''''aturrs ~./ ... < \ lbtchinl' El,w·Luying & '<JJ:r.!:r!,

Emergence Inr.l.lt)':Ui~·;n· at f)3_~(1"C 3rd ill~;t:lr ]O~l/j ,(ays .,. ''',. )

Dia.P31JSe anll \Vmtenng 3-...:J d(f\'s

II under Natural Condition -

in Japan ~"._/ III-Molt .... pupa in cocoon ~

-:-........-,..~\ / 4th illstar P 1..

1 pat 1011 ~ days) ;:/j days /j~6 / }QQ ~. ~ J4---- IV-Melt

'060 ~(j~8 dil)'" / ~ ,. f'----------~lp11lnlng ! 5th instur

Ripening

Newly hatched larvae 1st j l1stars

G T. Yokoyama

fit Il illstar~

pupae M(lth~

Duration of one generation varies according to genclkal nature and to treatment. The season of hatching can he adjusted ::>0 that man can rCHl'

silkworms in any seaSOn provided there are available mulberry leaves.

Silkworm Genetics Illustrated 7

1-2. Anatomy of the silkworm

Intestine occupie::; almost all the body cavity of the larva, and is divided into three parts, viz., fore-, mid- and hind-gut. The mid-gut is the largest extending over eight of the whole thirteen body segments.

Three pairs of the Malpighian vessels sLart from the rectum, run forwards along the outer surface of intestine turning back at around the third or t]1e fourth abdominal segmcnto; and J!nally each three unites into one vessel, opening inside the intestine at the hind part of the small intestine.

Larva respires through their spiracles opening at both sides of each body segment except the secone! and the third thoracic segments, on the posterior

1-3a Dissection view along dorsal side uf the silkworm

1, intestine, 2. trachea, ::I. Malpighian. vesoel, 4. teslb, 5. [Jui:itcdur i:iilkglalld

1-2b Showing afler removing intestine opened along ventral side

1. l11u:;c]e, 2. dorsal ves:o]cl, 3. testis, '1. tntchea, 5. middle :;ilkgland C~-day·old, 5th inslar), G, pOl:ltel'ior sill(glund, 7. foregut, 8. midgut, \:). hindgut

T, Ylltwyalll<l

horder of which a [lair til' fUlll'liullll'ss spiraclL'\';, so-calll'd I Ill' rudillll'lll spirack,

exists, It is aSflLllllL'd that t Iw rudiment }ipiral'll' i:·; a ,~t'I'lll disc of an adull

Olle, 'flw Illaill trullk; Ill' trachea rUIl tlmlll,l\lt Illl' lHldy Illllgitudinally at holll siC\cs, Each vair (If slliradl' ill a sugllH'lIl is ('OlllICl'il'd wilh it vl'lltral transverse lral'lJeil,

Dorsal Vl'ssd, Iwart, ie; rl1l1llill~~' tlmlligh Ihl! (]lIn.;al p;lrl IIf till' hody frol1l head t() lail. Nl~rVl' cllrd nlll,; through tltl' vl'lllral :-;illl' 1'1'11111 hl'ad to I'auclal l'nd, (,Olllll'clill,l!; till' Ilraill and g',lll,l!;lilHlllt' l'<lell HL').~nll'llt. Fal blldies lit- ullcl(,I:

til,) integ-lIml'llt and around tlIt' ilItl'slilll' playing an ililpllrtalll rtll(' ill Ilw metabolism slIch a:i st(lrn,l;t' (If mtllsUUll'(':" for ('lll'i'P;y SlIur!'(', ('x\'I'('1 illn Ill' uric acid lll' SYlltlll'sh1 or pnll.dn, TIlt' p,'llllacl lie,; Illll1w dm:·;nl :;idv Ill' llH' t'i).;hth hudySC!-(llll'llt, IIIW (Ill ('adl si(k Ill' till' dor:;al Vl':;';('1.

FurL[ll'l' des('l'iptiOll or I hv illl;tllllllY Ill"('(:;;:i<lI'Y foj' gl'IIl'1 i('HI l'xplitnali()Jl oI the silkw()rm will 1)(' )1;ivl'll ill Illl' fllll()willg' l'()ITI':qJllll<lillg ;';l'di()tls.

l-':!l' l'l'!I!;:'; :A'dillil at :ti)i["Illt'11

(If th(: ~;ilkwf>nll

1.. midgut, 4, Illiddll' divi!., of llliddk !:ilk. gland, :.l. llu:;(.c'riul' tlivi~. "r middlu >:ill,/;lalld, 4, jJo:;Il:rior ~ilkgland, 5. Iradl(::a, Ii. Malpi,lillian vu!.:~ui, 7, ()l!n()cytl!~i, H. fat hody

I-~8, Schematic ligures of silkgland

I-:.'d ~;ilkgtaJld ill lit" full .. ~r"WII larva

Silkgiaud of lIlal.lll'('([ larva

7 day old, 11lh im;Lar

Silkg-lancl is the second largest organ in lite silkworm body. It originatcH with the paired invagination in the labial segment. In the full-grown larva it.

Silkworm Genetics lllustratcli 9

occupies most part of the ventra-lateral side of the body from fourth to the eighlh segment. It is divided into three distinct parts, the anterior, the middle and the posterior part, while the middle part is again divided into three functionally different divisions. The fibroin, silk protein, is secreted in the posterior part; sericin I, the innermost sericin, in the posterior division of the middle part; sericin II, middle-layered sericin, in the middle division; sericin Ill, outermost sericin, in the anterior division of the middle part.

There are several kinds of coloring substances of silk, and the secretion of each is correlated with particular division of the silkgland.

Paired silkglands lead into aile spiner'ette in labium, and about the point of union of both glands two Filippi's glands, one to each silkgland, are attached. Several functions of Filippi's gland are assumed but not proved.

A

1-3 Schenmtk IigUl'c of sill,gland

~~:; Sm

~SGC . F

cross section

Side view of

silkgland in a body

right silkgland

A, anleriur silkgland; 13, anterior division of middle silkglancl; C, middle division of the same; D, posterior division of the same; E, posterior silkgland; Sr , sericin I; Su, sericin II; Sm, s·eticin III; F, fibroin; SGC, silkgland cell.

Sericitl III is secreted from I'l, ::;eridll II from C, sericin I from D and jibroin from E.

10 T. Yokuyalll<l

1-.1. Amino add compositioll of fiiJroin, sericin and COCOOIl Jihl~r

A tab Ie is exhihiled in which rceellt r('sLlI t s uf I he s( udy hy T. FUKUDA Hnel J. KmIMtlHA hy means of bioassay arl' sh()wn.

I-I i\lllinu Acid COllljloCiilioll ,,{ FiiJruin S,~rivi 11 alld CII"lIUIi Fii>l.'1'

Amillu add Fillrllill Sl'ril'ill l'''l'OOil (l(WI' (Silk prpll'ill)

,II ,\11 i ae ~K. ;HI~;)(;' .1. 110"',, ~~1. (I()n,;

argiuine II. H:l ,[. liD l.ljG

Hl>parl k add 1. (iO 1 Ii. Mil ri. fiO

gllil lImk aei,\ 1.:1', III. Ii;; ~. 1 II

glycilll' ,j~. HO H. (ill :::1. Ii II hi~t itlint' H. :~;) 1. ::\1 11.'i'::

i:>1.1 Ie uL"i Ill' 1.::0 0.1)0 1. ·Ifi

k~ul'ilw [. 1111 II. HH 1I.!)(i

I y~ii Ill) II.·I:.! ri. H,I I.:.!:.!

llwtlti'Hlilll' 11.11 O. I ri phL'llylalallilW I. 117 1),li:i 1.11

vrul i Ill' II, ,IH 1I.·It>

~,. ri Ill' 11.711 ::1). III IlL 1111

thrcUlli Ill) I. I:! ,. d. I" ,I :1,1111

tryptophan O.:.!!i II,·I!I

tYl'ut;i nl~ 1:1. 7!J :1. 1)0 I ~!. : ~!i

valinI.' ~. HX L. Hti :t 1 r;

1· !i. Cdlulw;c substallce oC cm:()UIl JilJl!1'

While slurlyinp; ('hl~l1lica\ llature or 1()Llsinl's,;-dcl\~,·t 1)1' silk, [\,1. ~;llJl\ll~:tI

found L1mt a cLlllskkrall[l> part oj" l\)usy Ilhri !lac clIII\-\h\\s oj" l'l'ilulo:,;\' ~;lI\)~,\allc\!

(l!lfi!il. It is sl~cl'elcd in Ow posterior divisiull or tilL' l1liddll' part or till! ~·\ilk

gl"lncl. The urder of the polYlllQriza\ ion or litis sLllmlalll'(! b ('olll[Jaralllc to /1-eellulllsl! uf plant lib~~r, i. c, l'1I111jJOSl!cI of ahout :.:()() lllllll'nilcs or .1.~ll.Il·()Sl!.

I-G. MeLahulic paLhway (If alllinu acids in silkworlll larva in J'l'lal i011 III silk production.

The illustratiulls of tIll' urig'in of rnain compOllent «l1lillO ad(h; of silk

protein arc shown based U,l the H!Ccn! sludy o[ T. FUKliDA using radiuactive 0 1•

It was proved Lhat phenylalanine of nllll1)l~rry leaf ch,tIll,(cS inlu tYl'O::-;iIW of silk and the inierrdations between glucose, glycilll~, glyoxylic acid alld serine arc ::-;1 III wn. Alanine is ~;u Pposl!cl to .be c()llnl'ctcd wi l il variouH pal hwaYH with pyruvic acid, <lHpal'tic add and oxulal:etic acid,


1-5 Cellulosic substance of cocoon fiber

M, ~I<I"'IW

[-() Metabolic pathway of amino acids in silkv,'(Tr:l larva in relation to silk production

~110 H~OH

!-IOCl! IICOII II(;OH

CH,OIl gJucose

COOH I (IINIl, dccorho)lyiuse ClI,NlI, COOII -~ coon

i1I1l\!10malonir. add glycine

\H,OII ~IINH, COOH serine

t ~1I()

COOH glyoxylic acid

COOH COOI-! ell, eH, bl /J.clcc"rhoxyiase CHNH, ell; CIINH, "---- COOl! yIlNII, tOOl( , C90H ,

il:.paI'Uc acid alanille glutanll~: aCid

i trnllsaminasc III . Itr<lIlSaminasc llmillation transaminase COOll

COOll Gr.l ell, hI, co tn, 60' coo II ~'()' COOI1 COOI-!

oxal~cct ic add (pyruvic acid) a~l=ctoglutnric acid

()

Cll'9"COOll l/~ CII'9IlCOOJI Nil. --> I NIl

, IIO / '

phcnrlalaninc tyrosine

c: radio;Jcli I'C <':" T. FUKUDA

11

12 T. Yokoyama

II. Hereditary Traits and Chromosome Maps

Genetical behavior~ of the silkworm have been studied by many investi

gators for a long time. The criteria of ~uch stuclies consist of various newly

discovered mutants and al~o varioLls noticeable characterislics inherited fr0111

olel times.

[Jombyx IJlrtlularill(( (lIl(.>OjJIli/1( mallc/arillal which is regarded as tIle anceslral

form of Bow")'x mort resembles the laiter in morphological characteristics anc!

can freely be mated with R. 1}lOri. The chr()mo~ome number in n. mandarinll

is 11=27, while in B. }}lori 11=28. In 11. )}lori there is a skin marking called

ll1oric(luc!, which is genetically proved to be identical with that in L!. lJlmzdal'intl.

The hereclitary traits in /lumbyx mori amount to 211, the sec()ncl largest

number of such characteristics among insects next to that of Drosop/tila. The

difference bet ween Hrlllzhyx anrl Drosop/ti/a is that in DOIll/JYx the heriLable

characterislics are observed in various stages or dl~vel(]pment espe.clally in

egg and larval stages, while ill lJrosoj)/iila mostly in imaginal slage.

T,lbk 1. Hl,reclilary I rail:; ill BO//I{Jyx lIlori

Chara<:ieri:;lics in

Larva Pupa

COCOOll

Moth

Total

Nu. uf (rail~)

1:~7

Ii 1[1

14

:m

J\ certain spontaneoLis mutant makes a special characterbt ic uf a raCl', but

in another case .il is common in various races. For example, LlIU fulluwing characterist ics are sped lie to different races:

striped marking (j)S) to Chinese race

quail marking Iql to Japanese race

dominant white cocoon (I) to European race

In the following a general explanation of the hereditary traits of Bombyx mori from egg to moth wi I [ be given:

1. Egg.

1) Egg color. The color of egg is determined by three components, i. e. the colors of the yol k, the serosa and the chorion.

The yolk color is usually light yellow, but in ~ome strains is deep and in

others light in color. The moth which belongs to the yellow blooded-white

cocoon strain lays eggs with very eleep yellow yolk. The color of serosa de-

Silkworm Gcnctks I1111~tratcd 13

velops after fertilization, In the nUll-hibernating egg the ,;ero~a remain~ col(Jl"le~s, but in the hibernating egg the pi,l!;mcnts in serusa begin to appear on

the secone! clay 01' laying and clevc1uLJ into tlle fixecl color in 3 10 "1 clays, There

are several kinds in serosa color, white, red, bru\\"l1, and dark brownish purple,

II-I ~1l Egg color

oorllIol egg _, I

dark colour IlOfJIl(JI cgO'~ light (olour

,.-

greeJl e\~,j llire)

grey t'1}J - hoaa • (/Jr )

grey egg-beIero" greyegq E-16 -I1cIJlO grey egg E -16-bderc COr) I Gr-16) (6r-1d)

light grey egg (L'J )

unslable. grey egg' bird .. eyed egg III i~hibilor ur Iig-hl !

({jfll ) {(itt!) grey egg (/ -(,!l )

II --1 normal egg-clark colc.Jl'

.. I ..

II .. ·--3 normal egg-light color l[~-3 green egg (Gre 1-4GA)i' II---4 grey egg--homo \Gr 11-6,\))

II--S grey egg-hetcro IGr 1l-(l,9i II-(j grey egg E-Hi-holllo (Gr-In II- 6.91

II--7 grey egg E-IG-heteru IGr-lG II·Cj,D) II-- 0 light grey egg (Lg 1I-6,l-G,9)

II--9 unstable grey egg (Gm JI-6.1--G.DJ

II--IO bird-eyed egg (Grb II--6,9) II -11 inhibitor of light grey egg ([-L,g II-G,l-G,\JJ

" Italics, Roman and Arabic numerals ill (he parentheses show gene symbols, chromosomes and gene loci, respectively,

14 T. Yokoyama

the last being ordinary color. The color of serosa usually coincides with eyecolor. The color of chorion is white or light yellow and in a few cases it is pinkish.

II-12--27 Egg color and the shape

red el.19 ire)' cocoa e~y Icuel brown egg-Z (1J..)

piled f99 ":, white ew·2 (11,,);·0 white egg-J (lVJ)' I Aojuku whilc·c!l!J' whilr'l"I}j Irons· tmnslucenl (W"') lucent (Qtlll)

- unferlilileli eiJ9 (linn! 1~9<J ((it" 1, dottillllPI SIKlIl t9\l (S.),

11-12 pink-eyed white egg (pc V-O.O) .,

11-13 brown egg-2 and red egg (b~ VI-S.U; re V-31.7) Il-I4 red egg (re V-31.7) II-IS cocoa egg (we)

II-I6 brown egg-2 (b~ VI-S.O) II-I7 brown egg IVII II-IS white egg-I (Wj X-O.O) II-E) piled egg II-2U white egg-2 (W2 X-3A) II-2I white egg-3 (W3 X-G.g)

II-22 Aojuku white-egg translucent-larval skin is translucent (zool X-G.g) II--23 white-egg translucent-larval skin is translucent ({Jew X) II-24 white-side egg (se XV-D.O) 1I-25 giant egg (Ge 1-14.0)

II-2G dominant small egg-an X-ray mutant (Sm III-±21.U) II-27 recessive trimolting (rl VlI-±9.0)


21 Egg shape. The normal egg is short ellipsoid, but there are mutants in which the egg is spindle-shaped or long ellipsoid. The kidney-shaped egg, the lethal spindle egg and some other eggs are accompanied by lethal genes_

II·28~39 Egg shape and egg.shell color

spiid~.~pc4 C!IlJ . ellipSGid egg (rIp) kidney·shaped egq fJPJ (/({)

II - 28 spindle-shaped egg (sp)

II -29 ellipsoid egg (elp)

II-3D kidney-shaped egg Iki) II-31 lethal spindle egg (hPj II-32 no·glue (Ng XII-D.O) II-33 brown egg lethal ({-be)

II-34 lethal non·hibernating egg (/'n XII-21.0) II -35 white egg lethal (l-we)

II-36 white egg-shell II -37 reddish egg·shell II -38 pale green egg-shell II-39 green egg-shell (Gl'e~II-6.9)

16 T. Yokoyama

2. Ant or newly hatched larva. In ordinary varieties it is black showing a certain degree of fluctuation

in the shade of color. There are two mutants hoth choc(llate in color, but one dominant and the other recessive.

II -'lG Shori bristle (sb)

Newly hatched larva

1I -110 normal color II -41 chocolate I.ef/ X III-OJ)) II--12 chocolate and white egg-2 (c11 XIII-O.n; Ui, X-3.4) 11--43 dominant chocolate (I-a IX--5.9) II --44 lethal non-molting-l (Ilnll)

II-45 lethal non-molting-2 (mIl 2)

II-46 :short bristle (so)

3. Larva.

-i- sb

1) Marking::>. The larval markings are not clear in younger worms till the third instal', but clearly distinguished after the fourth. There are large


number of different larval markings which are comparable to the imaginal

characteristics in Drosophila. :.!.) Color of the skin. It is white with greenish, yellowish, or reddish

tint, but there are mutants in which the skin color is greenish yellow or the skin is translucent owing to the small amount or nothing of uric acid in the epithelial cells, called" oily". Several genes locating in different chromosomes are known which express almost the same characteristics, "oily!t.

~l.\ mood color. It is colorless or yellow, and the color of blood corresponds to tIl(' color of COCODn, but thC're is a mutant which has yellow blood

and spins white cocoon. 4.1 Body shape. There arc wide differences in size, and shape. There

are mutants in which there arc sllpernumerolls prolcgs, knobs on the dorsal surface of the body, or with the skin highly tensed, hard, ancI "stony",

In the silkworm there are 3--, .4-,5- and 0-- molting strains and 1-, 2-, and I11ultivoltine races. European race is always univoltine ancl tropical race is

J11 uIt i voltine.

II -47 sex -linked translucent (os 1-0.01

JI-49 Chinese translucent (oc V-40.0)

II-48 distinct translucent (od 1-49.6)

II-50 Kinshiryu translucent (ol~ V-4.7)

18 T. Yokoyama

II--51 a translucent and black pupa (bP XI-I7.I)

II--53 oal-mottlcc1 translucent (oat II-26,7)

II -55 plain eye-spotted (p' II-O.O)

II -52 od-mottlec1 translucent (od"' 1-49,6)

II --[j4 plain (j) Il--O.O)

II -56 normal pattern (+P II-O.O)


II-57 moricaud and lemon-the pattern resembles that of B.

malldal'ina (PM II-O.O; lem III-22.3.:

II--59 striped I P' II-D.O.!

II-61 S-mottled-a chromosomal aberrant

II -58 moricatld and zebra (PM II-O'!); 2(1 1lI-1.5!

II-GO striped and dominant chocolate (p' II-·O.O; I-a IX-5.D)

II-52 striped 2 and moricaud (S2 II-6.l; pM II-D.D)

19

20 T. Yokoyama

II-G3 dilute striped (Sa II~(i,l)

II-65 black (PB II-O.DJ

. II-67 apodal and zebra (ap III-O.O; Ze III-1.5)

IT (i4 ventral·striped (PO no,O)

II~-(i() black and dominant chocolate Ii)}) II n.n; l-rr 1\ [i.HI

II -G8 zebra faded (Z(/ III~ 1.5)


II -69 lemon (lem III-22.3)

II -II multilunar 1:5. Ii, 8 segments) IL lV-O.(l1

II--I~l Il1ultilunar 1'1---S segl~lentS) (L lV-O.O)

II-IO multilunar (5, 8 segments) (L IV-O.O)

II-72 multilunar 15-8 segments) (L IV-D.G)

21

22 T. Yokoyama

II-75 multi1unar (4-9 segments) (L IV-O.D)

multilunar (4-10 segments'! (L IV-O.O)

II-79 stick (sk IV-25,S)

II--76 multilunar (5-10 segments) (L IV-fLO)

II-78 multilunar and speckled-an X-ray mutant (L IV-O.O; ,Spt' IV--33.1)

U---SO Kp supernumerary legs (EKPVI-O.O)


extra-crescents and legs (EE:' VI-D.O)

JI--83 double crescents (!~'}I VI-O.O)

II -85 new additional crescents (EN VI-O.O)

II-84 additional crescents (ECf! Vl-O.O)

II -86 no crescent marking (Nc Vr--l.4)

23

24 1'. Yol):oyalll<l

~""" _. ..... 1

II --87 quail and plain, 1 (q VII-O.(]; j) II-O.())

U-SB quail and cheek and tail spots (q VII-OJ); cis)

II-91 stony (sf VIII)

Il-S8 quail (;l'lc1 pl<:~ie, :2

II} VII-O,(); j) lI-O.())

Il--90 quail (II VII-O,O: V'II-O.l))

II-93 dilute black (bd lX-G,7)

Silkworm Gem~tics Illustrated

II -93 knobbed I K XI-O.Q)

II-95 dirly Wi XIV-O.O)

II-97 sooty (so)

JI-94 burnt-an X-ray mutant Wu XI-5.5)

II -9G red skin

II-98 extra spiracle (es XII)

25

26

II--H~) ursa (U XIV-2.7)

T. Yokoyama r '.

II-IOl solid black-eye spot (blind)

II-I 00 ursa and knobbed (U XIV-2.7; K XI-O.O)

II-I02 red blood (rb)

II-I03 brown head and tall SlJots (bts)

II-IOl! narrow breast (nb)


II-I05 dominant retarded

II-I07 second-segment monster (mse II)

II-lOg hereditary mosaic, cit P' and + P' (mo)

II-lOG recessi ve retarded

II-lOS hereditary mosaic, Ze and -I- (rno)

II-110 mosaic (l-Sp)

27

28 T. Y okoyaI1la

r 1- ! I.:: :;~)uty (SI))

II-1l5 apodal I (fP lIl-1I.0)

II-117 burnt--an X-ray mutant (lilt XI-G.G)

l[ 11~ black pupa (bjJ XI-I7.1)

11- I-I·! !EkruptLrllLls 1111/) XI--2'-1.0)

1I~·11 (i knobbed Ii( XI-O.D)

lI--1l8 crayfish (c/ XIlI--l1.8)

Silkworm G":I1t:!tics Illustrated

II-1El .eurltc1 Will:,; ,ele, 1I-1Z0 wingless (fl ;(-0.03;

4. Pupa. 1) Shape. In g'eneral the form of silkworm pupa is the same as uSLlal

LepidopleroLls one, but there are a few mutants which show abnormality in

wings or in other Imrts of the body.

2) Colur. Usually the colur of pupa is brown, but: there are mutants in

which the color is black, e. g. black pupa, bj).

5. COCOOI1.

1 i Shape. Ellipsoid is very common, but in Chinese race there arc many

varieties which spin ~,pherical uK'OtmS, and in Japanese race it is peanut-shaped.

21 Size. There is a wick range of difference in size from 20 mm to 60

111111 in length and ,'rom (J.t g to ::LO g in wdght.

3.1 Color. There are two main colors, yellow and white, and besides these

there are green, or reddish colors.

II--121 normal white (-i r I[-:~5-(])

II-122 yellow inhibitor II IX, 0.0)

Il-12:l sooty plain white '.(( IX-O.O) Jl-124 green a ami green [J (Ga; GfJ VrI--7.0) II-125 green (' IGI: XV--7.8) II-12G flesh-culored and inner-white IF V1-13.G; +c XII-14.0)

1I-127 cinnamon-buff and inner-white ICiI; F VI-'l::l.G; ·1-" XII-H.O) II-128 pin];: anc! inner-white ! Fh; F VI-l:Ui; +c XJI-14.m rI-12~1 pink and inner-white (Pli; F VI-1~l.(i; -I ,. XlI-14JJ)

Il-130 golden yellow (C XII-I-1.UI

II-131 dilute yellow leI XI! 14.11)

II-132 s~ra\v-colorecl Ie" XII--H.O.I

II-133 inr,Cl'-y(.llow ,e Y.I 1- U.O 1

II-13-! yellow blood and wllite cocoun I 1-'" VI-13.li; -f.' XU--U.O!

II-l35 flesh -colored and inner-yellll\v (F V 1-13,(j; C XII-14.0)

1I-13G cinnamoll-buff and inner-yellow \Cb; F VI-l:1.G; ei XII-l4.0)

30 T. Yokoyama

Cocoons

Il-1:~l + y 11-122 I II-l~3 a 11~124 CaCh

1I-12S Gt; 1I-12G PI G 1I-127 CbF+G II-128 PkCbP+ C

II-129 PkF+C II-UO C II-131 Cd 11-132 C"

11-133 Ct 1I-1:J5 FCi II-136 Cbl·Ct

][-137 PkFC' Il-US ]i1pilne,;e type Il-139 Eurupean type II-HU Chillc~c type

11-141 tropical type I1-U~ mandarin<l lype Il-143 smoolh surface II-IH rough surface

1I-145 fluff y cocoon

1I-150 polypupal cO~OIJa

Silkworm Genetics Illu,tratcd

II-137 pink and inner-yellow (Pk; F VI-13.G; Ci XIH4.0) II-138 Japanese type-cocoon shape II-I 39 European type

II-140 Chinese type

II-141 tropical type

II-142 mandarina type

II-143 smooth surface

II-I44 rough surface II-145 fluffy cocoon

II-146 sericin cocoon-naked pupa (Nel)

II-I/17 peaked cocoon

II-148 flattened cocoon

II-149 double cocoon II-I 50 polypupaI cocoon

G. Moth.

31

1) Shape. There are mutants in wing such as vestigial or short wing

like Drosophila, but the number of varieties is known far smaller in Bombyx than in Dmsoplzila.

2) Color. In B. mandarina the color of wing is dark brown with black patch

on the tip of wing, but in B. mori it is white except a variety" Papillon nair":

II-15I Bombyx mai,tdarina

II-152 normal

S2

1[-153 bimolting (rt XlI-±9.0; M:J VI-3.0)

1I--15cl recessive trilllolting itt XII-~H).(l)

II-Hi5 1l1icropterous Imp XI-:'~4.U)

II-1S6 black moth (Em)

Silbvorm Genetics Illustrated 33

II-I 57 wild wing-spot (Ws)

II-15S white banded black wing (wn V)

1I-1!19 lmobbccl (!( XI-O.())

II-160 burnt-an X-ray mutant (Eu XI-5.5)

34 T. Yokoyama

II~151 vestigial-an X-ray~mt1tant (Vg 1-38.7)

II-162 wingless (fl X-O.08)

II-163 mosaic (l-sP)

3) Color of eyes. It is black, red or white corresponding to the color of eggs as mentioned before.

The chromo30me maps which have been made clear till now are shown in II-164.


~

~ .::::.

~ ~~~~ Ei

~~ 0 '" ~ ({I

S '"'" .... .., 0 ~

;:: S .., '-' 0 a ~ >..

~ (/"1 Cj ,._. (I) ~ '" ~ coL ..t:: "" U ::l ~ ~ ~ ::: 0 ~~

(.) 0 IS "'"

;.l-<

~ ~ :-- ,_ blJ

~ "

~ ." -< ~~.~ .... 4l

'" I 112 r:s I I ..... ! ..... ' ~ J:: ~ '" 00 00:-

C.! "'" 0 ,,·i ocia)~ f-t

~ .J;! '<? '" "" M '.l 0 ,_; G '~~

~ "1::l

~ 0' ...:. ... n,

"'~ "" ~

~ :;.:

0 ..,. d

d1 ::: ,..... ~

C']

t U'>

X :.:: ...:. Ol J; 1 I ..L I ~ ...

Lr') ..... o 0 Q 0 ·9 .• ~ <Il >:. ...:i '-1');:::00 "" ;; ,..... .:-J ..::

~ 'i:: ~~~ ~' ;;: n, ..:: fi~ >< J,_ ~ 1 :::. '; >-

" ;,;; Cj ~ 0> Q ,q

M 0 '" G ... - 2:- " kl "< 00 Q tt ~" .2 t:s .2:~~ .:; ~

..... - III <1- kl ~ + OJ «l ",-~ 0 ~t~"'" }1 _- ~

0 LQIDl"': '; ~ ",-'H .. 0

~ '" '" q CI'J. ttl r4~ "''''' " (fJ ~ c ~ h{' ';r:. ... p. 0 ..... 0:- w CI'J. + kl '" 8 c..-i l.~ 2 '? +1..(:) ~ .... ~: ~\ ..,

O,J s: I;::< Cj>- " ro 8 " 0 t-- I I I t/J

C/J Ul 0 ""q <=> 0: 0 o ~ l..!. en ,_;

'" 8 +1 C']

tq~~' 1:'1· .... C;; "" + 0 """'= ...:. n, .... s: ..r:: I I I' II I I . ... " .. ,

U 0"'1'0 oM ~ t,~ ,..,"" .. ' oded M ,-,: OHM "'1'

"'= ,-I ~I

~ '"' ~ ~ .-I '" C , > ~ ..... 1'- "" ..... '=' t~ GO -q.

0 ,_,; ...... 0 ..... Co") !".) >oJ

.z~ "'= ~ ..,.

~ ...:) y ;::: " 8 l.' co

00,.., Her.> er.> M ~ :'7 ({I Cl " o~ ~M~ l:) <Ii Cl) -q. '" -<l,~

.......... ,-1 ~~ ~] ~1 :8 "" :::: tl '" ":::C/J ,;. ro ~ '" 9 1 I I II '" .. -q. :t., .... "" LD '" ,.")00 {l, '" ~ OH ,....; C'lC'i +

>- M C\lC'1 ......

~ {l, C/JCj +I +1:::'" ~ = <::> ,.....", <0 t- tt:! ~ 0 t.::ir.e tr:ic.ci ,_; .., ""'~ '" ~~fS c3

"'1 C'l ~1 ...:. ,o~ 'ti ..,.. '"'- "':'Cj '" - III...:) I I I '"""#--1-

<:::. 0;.:,0, '" -.,;< [~ o~ IJ-:J ~',;_ c:-'

~~ <6 r.O . to to c) - N "''<t' "'" - N <" - P._l_ 1i+ $: .._,. Female 'determinor

36 T. Yokoyama

Chromosome Maps of Bombyx mori L.

Explanation of the symbols

I-chromosome: os, sex-linked translucent (skin character) I-a, lethal a

II -chromosome p·alleles

Lm, late maturing (voltinism) Ge, giant egg e, elongate (body shape) I-e, lethal e Vg, vestigial (wing) I-b, lethal b Gre, green egg (egg shell color) od, distinct translucent (skin character) odm, od mottled translucent (skin character)

p, plain (skin marking) pI, semi plain (skin marking) +P, normal marking (skin marking) +P', lightest normal marking (skin marking) +P', light normal marking (skin marking) +P', standard normal marking (skin marking) +P', dark normal marking (skin marking) pB, black (skin marking) pD, donml spot (skin marking) pll, ventral·striped (skin marldng) pL, light crescent (skin marking) pM, moricaud (skin marking) pMa, mandal"lna moricaud (skin marking) pS, striped (skin marking) pSt, pale striped (skin marking) psa, sable (skin marldng) pSa-2, sable-2 (skin marking)

8-alleles: +~, normal marking (skin marking) 8, new striped (skin marking) 8,t, dilute striped (skin marking) S1-8, inhibitor of new striped (skin marking) 8"', white-thorax striped (skin marking) 52, striped 2 (skin marking)


Gr-alleles

III -chromosome

IV --chromosome

V -chromosome

+(1r, normal color (egg-shell colOr) Gr, grey egg (egg-shell color) GrE, grey egg E-IG (egg-shell color) Grl, light grey (egg-shell color) GrB

, bird-eyed egg (egg-shell color and shape)

Y, yellow blood (blood color) oal, oal mottled translucent (skin character) Re, rusty (cocoon color)

ap, apodal (degenerated thoracic legs) Ze, zebra (skin marking) zer, zebra faded (skin marking) L-III, lethal III (embryonic lethal) lem, lemon (body color) Sm, small egg (egg size) ts, tail spot (pigment)

L, multilunar (skin marking) l-w, lethal white-rot egg mal, larval malformation sk, stick (body shape) S'pc, speckled (skin marking)

37

pe, pink eyed white egg (serosa color associated with pink eye)

ok, Kinshiryu translucent (skin character) re, red (serosa color) oc, Chinese translucent (skin character) bw, black-banded wing (wing color)

VI -chromosome E-allcies

+B, normal (body shape and skin marking) E, plain extra legs iE-allelic group) F ''', additional crescents (E-allelic group) ED, double crescents (E-allelic group) ED", double siars (E-allelic group) Ell, II extra crescents (E-allelic group) EKP, Kp supernumerary leg.s (E-allelic group) EEL, extra crescents and legs (E-allelic group)

38

VII -chromosome

T. Yokoyama

EN, new additional crescents (E-allelic group) ENe, no-crescent supernumerary legs (It'-allelic group) ENP, Np, supernumerary legs (E-allelic group)

Nt, No crescent marking (skin marking) Ma, trimolting (moltinism)

I_AI, tetramoliing (moltinism)

liP, pental110lting (moltinism) b~, brown egg-2 (serosa color) I~i, kidney (egg shape) F, f1esh (cocoon {'olor) l-Il, lethal-Il (embryonic lethal) Ys, straw (cocoon color) bo, ordinary browll (serosa color, ordinarily inherited)

q, quail (skin marking) Gb, green b (cocoon color) 1·t, recessive trimolting (molt.inisll1) oM, Bs mottled translucent (skin character)

VIII -chromosome

IX -chromosome

X -chromosome

XI -chromosome

ae, digestive juice amylase negaLive (digestive fluid) be, body fluid amylase negative (blood) st, stony (body shape)

I, yellow inhibitor (blooc] color) If, sooty plain white (lacking fundamental gene for yellow

cocoon)

I-a, dominant chocolate (body color) 1Id, dilute black (body color) og, Giallo As('oli translucent (skin character)

WI, white egg-l (serosa color) II, wingless (wings degenerated) w~, white egg-2 (serosa color) 1113• white egg-::l (serosa color) Will, AOjllku white egg and translucent. (serosa color and

skin character) oew, white egg translucent (skin character)

K, knobbed (skin character) BlI, burnt (skin character)

XII -chromosome


I-10, Iethal-IO (embryonic lethal) bp, black pupa (skin color of pupa) mp, micropterous (small wing)

Ng, no glue (non-adhesive of egg) C, golden yellow (cocoon colOr) C', yellow inner layer (cocoon color) ton, lethal non-hibernating egg I'd, round (egg shape) es, extra spiracle ms, multistars (skin marking)

XIII -chromosome

XIV ---chromosome

XV -chromosome

cit, chocolate (body color) 1/, crayfish (body shape of pupa)

odk, E15 translucent (skin character) Nt, no-IUller (skin marking) U, ursa (bear) (skin marking) UlJ" brown ursa (skin marking) oa, Aojuku translucent (skin character) Di, dirty (skin marking)

S'e, white side egg (serosa color) Gc, green-c (cocoon color)

Other chromosomes represented tentatively by each of the following genes. Bnz, black moth (body color of moth)

39

Ym, yellow molting (color of excretes of Malpighian vessels while ecdisis)

bt, blind (skin marking) Ill, lustrous (eye color) Nil, naked pupa (sericin cocoon) ::ill, spindle-shaped (egg shape) ge, ge01l1ctrid (body shape) cts, cheek and tail spot (skin marking) rb, red blood (blood color) so, sooty, (body color) otm, t-motted translucent (skin character) N-Ns, new no-stars (skin marking) nb, narrow breast (body shape)

4.0 T. Yokoyama

III. Cytology and Ueproduction

The number of chromosomes of Bombyx mori is 28 in haploid. The form

of chromosome resembles each other and each chromosome cannot be disc criminated. In the case of silkworm, the genetical conclusion is only partly

supported by cytological observations. The following items are worth exhibiting in the cytology of the silkworm:

heteropycnosis of sex-chromosome, dimorphism in spermatozoa: eupyrene and apyrene, difference in chromosome between Bombyx mori and H lnanda1"ina.

Besides the above, the exhibition of sLlch interesting phenomena as mosaics, sex-determination or polyploid will be made under different. headings.

(cll r01110S0111es ) III-1 Diploid, triploid, tetraploid in spermatocyte and Oocyte.

The silkworm, Bombyx mori, has 28 pairs of chromosomes in diploid. It is easy to count them at the first metaphase of the maturation division in both oOcyte and spermatocyte. The eli vision takes place in an egg immecliately after egg-laying and in testis during the fifth larval instal'.

Although polyploiclies have rarely been observed in animals, polyploiclies in the silkworm have been very frequently reported. Most of them are

triploids and tetraploids. Only one case was reported of hexaploid by KAWAGUCHI (1938). Polyploids are easily obtained by means of centrifugation (KAWAGUCHI, 193~1), temperature shock (a high temperature, HASIMOTO 1933; a low temperature, MUROGA 1948) and colchicine coating (I-IIROBE, 193n) applied to yound eggs at the maturation division which occurs in one hour after oviposition.

Polyploid first reported in the silkworm was the one which occurred spontaneously in the heritable mosaic strain. TANAKA (Ul281 found a few exceptional females of sex-linked inheritance in the mosaic strain and attributed them to polyploidy. This was suggested also in cytological study of the mosaic strain by GOLDSCHMIDT and KATSUKI (1928) through their observation that one of a triploid egg nuclei was fertilized by a normal sperm nucleus. Later I-IASIMOTO (ln34) confirmed genetically and cytologically the polyploid in the mosaic strain.

SATO (1929) observed polyploids of parthenogenetic origin. Polyploids which occurred in the strains with chromosomal aberration were reported by ARUGA (1939) and TAZIMA (1943). Polyploids sometimes occur also in progeny of interspecific hybrid between B. mori and B. 1nanciarina.

KAWAGUCHI (1934, 1936, 1938) obtained polyploicls by centrifuging eggs and studied the cause of their sterility which seemed to be a parallel phenomenon with the pc::culiar behavior of sex-chromosomes in the course of


gametogenesis of both sexes especially in triploid. His studies, together with I-lAsIMoTo's, have largely contributed to the elucidation of sex determination mechanism of this insect.

III-2 Chromosome in spermatocyte in the Fl hybrid of B. 11Wri and B. 11landarina.

KAWAGUCHI (1928) is of opinion that the domestic silkworm, B. mod, might be derived from the wild one, B. mandarina. This is because it is easy to cross each other and at the first metaphase of spermatocyte division of the 1"1 there appear 26 bivalents and 1 trivalent, the latter of which is reasonably considered to consist of three chromosomes, two from mon and one from mandarina.

III-3 Heteropycnosis of presumed sex·chromosome. Sex-chromosome can not be discriminated morphologically in the course

ot gametogenesis of the silkworm. KAWAGUCHI (1(:)28) reported that one or two chromosomes which showed heterQpycnosis were connected with nucleolus of the nurse cell and that of the ovar:ian cell bel are differentiation into egg

r',~

and nurse cells. He suggested thaf'the chromosome might be sex-chromosome.

III-I

III-2

IlI-3

III-l~3. Chromosome and nutleus in Bomby:x; mod and others

,I

1_<1. Diploid (n = 2R) in

slJermatoq'lc

I-~:. Triploid (n:·12±)

in s.p~f'matocy[c

I-b. Diploid (n~28) in

{JDCytc

I-d. Tetraploid (n-56) in spermatocyte

lri\'alent: one from ""maarina and two from mad

. '~,,.,

'Ii' 2. Chromosome in sperma[otVle in thl!' F I o( B. m01'l ..: B. mando,-ina.

Heteropycnosis oC presumed sex.chromosome

C:J GJ Nucleus in oocyte before Nucleus In The same The same in differentiation Into egg nutrJii\;e cell in triplOid Lymantr;a 4nd nutritive cells in in. 8. mor; dis/Klr' B. morl

E. KAWAGUCHI

T. Yokoyama

(Reproduction) III-4 Location of gonad in larva.

Position of gonads is shown by a photograph. They are located uncler the dOl'sal integument of the [)th abdominal segment.

III--5 Imaginal eliscs of reproductive organs: Ishi wata;s spots in female and Herold's spot· in male.

During the larval stage, male and female are distinguished with some spots located at the ventral side of the 8th and the Dth abdominal segments. Female has two pairs uf spots called Ishiwata's spots; one pair in the 8th

s2gment and the other in the !JLh segment. On the other hanel, male has one Herold's spot in tlw median point on the border of hoth segments. These are clearly ()hs<.~rvab[e in early sLage of the last larval instar. This was llsed as criteria for distinguishing male ane! female, contributing very much to the production of hybrid ep;gs.

nI--6 Pupae and moths of both sexes. Though the both sexes are distinguishable during the larval stage, the

difference between the both sexes becomes clearer in adult stages. They can be discriminated clearly not only by the external genitals but also by the shape of antennae and .wings and size of the body.

III-g

III-7

I 1I·-5

L GCloacb of die lOll va ;]n~ ;' u;t(ing under the inll'gUntL!l1t Ilf fullowing purti!lll. ,fr', /

'~~\t,~~ {~'.

3. Pupae, 4. Mut Ii:,_ ~~ (Ie/I) and mating ~ (rig"t)

~. d~w uf the pu::.tcriur .. d Ihe last ill~Jlar larv;l SUlI1I afler Illulling, ~,howil1g I~lIIw ":l'A'fi !~Iand in

'l' (It'/t) and Ih~RuLn'l_i gland in :t; (right). Even in larval ~itage, if pnd 8 ilfl' easily dhilinglli::;hablc

widl the'iI.~ imaginal dh;CR of gon;hl. The d i~i~U ... t:1 y has lilrgc!y conlriiluL{!u lhe egg pruducing indu::;ilry.

.,,01

5. !::idll.:lU~lil- lig. uf ;~ n!pl'(ldU~Li\'c sy~tCJll Just before ovillositiuII.

1II-7 (!?) be bursa copulat.rix, lIb ductus bursae, cls ducL. seminal is, cit duct. tur(:uusLls, gr glandula n~ceJltaculi, gIll gla. I11UC[)!;;[,

ip intesLinus postcrius, uri, ovidtlcttls p'cminl1s (Jcl~ (IviclLlctu~ C'onll11unls, (IV iubus uvaril1s, rs reccptcaculum seminis, v vagina wilhout egg, vt vestibulm with an egg.

1II-7 (c',) aeld ampulla ductus

dcferentis, dd ductus deferens, ga gl. alba, gl gl. lacteola, gp :v;l. pr()~tatica, gpl g I. pell ueida, gs gl. spermatophorae, ]l penis, t testis, VR vesicula scminalis. 5 & G after S. OMURA

Silkwurm Genetics Illustrated 43

1II-7 Anatomy of adult reproductive system in both female and male. Adult reproductive system in both sexes were carefully studied by ()MURA

(1938). He elucidated not only the anatomy of these organs but also the physiological function of every part of reproductive systems of both sexes for fertilization employing a technique of artificial insemination devised by

him. lII-8 Dimorphism in spermatozoa; eupyrene and apyrene.

MACHIDA (H)29) reported of apyrene spermatozoa yielded in follicle of normal testis mixed with eupyrene spermatozoa. The completed eupyrene spermatozoa appear at the end of larval feeding stage and gradually increase in number with age, while the completed apyrene hegins to appear from the day of pupation. On the last day of pupal stage, the apyrene exceeds the eupyrene in number. No apyrene spermatozoon is found in vas deferens and any other outer part of testis. Therefore, it seems that they may be dissolved at the basal part of the follicle at which the cyst membranes of eupyrene spermatozoa are broken. In fact, the apyrene spermatozoa degenerate in aqueous solution of acid, base and salt in a certain concentration, while the eupyrene do not with the exception of t.heir cyst membranes which are more or less dissol ved.

III-8. Dimorphism in spermatozoa

Bundlt' of s'p~rlll<Lto.:oa in mille SpL'TIIl:thlWit Tdl~d.s.ing th~ir l;umlle reproductive organ in f(~millc rf'pruducti\'(: I,Jrgan

A few of spermatozoa entering an egg through the micftJpylc

MJ\ctuOA

44 T. Yokoyama

IV. Sex Determination

A sex linked inheritance was first 10und by TANAKA (191G). The type of sex·chromosome in the silkworm is ZZ in male and ZW in female. I-IASIMOTO

(1933) has ascertained that the W-chromosome nearly monopolizes the power of determination of femaleness through the findings that even ZZW and ZZZW individuals in the triploid and tetraploid statcs respectively become normal females. TAZIMA (19M) has given further proof to thi:s conclusion by his discovery of a strain which has a piece of an auLo:some bearing a marker gene translocated on W. He has succeeded in finding the approximate locus of the sex-determiner on W by using strains wilh deflciendes of various lengths and involving different regions of the chromosome. Furlhermore, he examined the part played by the Z-chr01110S0tl1C in the determination of sex by using strains having various deletions each involving different regions of the chromosome. Thus, he has definitely made out that in the silkworm the determination of female sex depends solely upon the presence of the W-chrol110some. whereas the power of the Z-chroI1losol11C in c1elel'mining maleness is apparently much weaker. He has also demonstrated that l.he determiner of femaleness is localized in a particular region of W-chromos(nue without being diffusely distribuled 011 it.

The exhibition is arranged as follows: 1. The chromosome maps of Z and W chromosomes. 2. Diagram of the mechanism of sex-determination in the silkworm.

The chromosomal constitulioll of both sexes had first been genetically presumed by TANAKA in 1916, namely the female is ZW and the male ZZ. It was, howcver, very c1ifiiclllt to identify cytologically the sex chromosome.

Several morphological gene loci (seven loci) have been found on Z chrolllosome, but on W chrolllosome not a single morphological gene locus has been known yet. By the irradiation of X-rays several kinds of deficiencies have been induced on Z chromosome. Males heterozygolls for any of these deficiencies can sllrvi ve, while hemizygolls females for the same deficiencies are

VI-I. The maps uf Z and W chrumusome

z II I I I I Lm

r., £It Vg (Jrc n( o.~ I-a Ge

0.01. 6 H.O :-lG. 4:38, 7 46.4 49.6 . (Ior:us unlmown)

•• female determinor

~ '------_..,.-_____ _.J'-~,

U W Z


not viable. Therefore, even a small portion of Z chromosome is considered to be necessary to maintain the normal physiological function in the female, while W chromosome seems to lack of all these functional genes. Thus W is thought to be physiologically useless.

In 1933 HASIMOTO obtained a very interesting result on the role of W chromosome. He exposed the F I eggs from the crossing of Z+ IW l' X ZOd IZM 0 to a high temperature of 40·C. for one hour immediately after laying. Among F I individuals he obtained several females exceptional to the rule of the crisscross inheritance of sex-linked ad gene, of which the most remarkable were triploids and tetraploids.

As he could not obtain tetraploid male, all of the tetraploid females were left to mate to diploid male (od/od) and they gave only triploid individuals in the next generation. Though segregation of + and od was observed with the back-cross ratio of 1: 1, the sex ratio was altogether different from 1: 1 yielding more than 80.% of female. The result was explained by HASIMOTO

by postulating a preferential homotypic conjugation among two kinds of sex chromosome and existence of a strong positive female determining gene on W chromosome (lV-2). Thus he first emphasized the role of W chromosome in determination of the sex of the silkworm. There were, however, no methods to prove this, because all of the offspring were triploids and abortive.

IV-2. Abnormal sex·ratio in triploids and presumption of female determining gene

~. . AAZZ AAZW

~ ----.: __ --..:~ !f

0t AAA;WW high 'tempcra~~re treatment gametes

4n female

meiosis in 4n female Cd

AAZW +

AAZW

"

sperm 1 "".

fused nuclei of egg and po lar bodys

AAAAZZWW

1 + +

AAZWW· AAZ ---od-- '4 AAZ AAZWW

1 1

In offspring from 4n !f x2n(od) S 1 rood od+ od+

3AZZW 3AZZW

!f I' 4

3AZZWW

'i' 1

3AZZ

~

3AZZWW

!jl

"" ~ 3AZZ

~

1

46 T. Yokoyama

In 19,11, TAZIMA discovered a translocation between W ancl II chromosome

in which W chromosome was marked with two noticeable genes tor larv,ll charader locating on the I [ chromosome attached at one end of W. By using this translocated W he verified clearly lL"SIMOTO'S view and concluded that the role of W in sex determination is cledsi ve () V--3).

IV-3. Verilication of female·gene presumptiull on the W chromosome by using lranslocalion

os [l_-==:I

r:= 1.1 ad

+ ,+~

u ____ .::::J l~-=JI IT:~~_:::_=J l::::::--= os od os ad

+ II fr':itl, os!fl, + 11 P,'ia I od~! os, + 6 +. oJ Q

L_x------------~

fi( __ J C=:::-=:-..::::J +p [~I i _______ =

. . ........ ~ .......... ...

_,---------.,

nChcmi.l tlf lllUlui.d

lranslucatiun

The relat.ion iJet ween the ratio of s('x chrom()s()mes to tlte llumher of set of aut.osomes and sex expression was studied by HASIl\(OTO, KAWAGUC[[I and 'L'l.ZII>.L'I.. The results are sLlmmerized ill the Tablc (IV-,ll. Whenever W chromosome is present the individuals becomes invariably female, while its absence always prom iscs to 111ak~ male. It is, therefore, clearly known that female is det.ermined by the prescnce of only one 'vV chromosome irresp~ctive of the number of autosomal sets or of Z chromosomes.

Apart from the role of W, the effect of Z on sex expression should be tested. Partial duplication and deficiency of Z chromosome were examined of their effectiveness 011 sex determination by using several strains, but no sexual alteration were observed under any supernumcral or deficient condition of Z chromosome CIV-5). Thus it was concluded that sex is decisively determined by the presence or absence of VV chromosome in the silkworm.

Silkworm Genetks IlILl~trated 47

IV-4. Sex determination in pulyploicl~. with special reference to the ratio of sex chromosomes to autosomes

ploidy

2n

3n

sex chromo.,

SDme

_fragemcIlt

left deficiency

-m-iddle-- ---(leletioll

right deficiency

number of autosomal sets

All..

AAA

AAAA

number of Z·ch.

zz Z

Z

ZZ

ZZZ

ZZ

zz ZZZ

zz

number of W-eh.

W

W

WW

W

WW

sex expression

IV-5. Effect of partial duplication or deficiency of the Z chromosome upon the sex expression

bypoploidy hyperploidy

n-ull1ber of i numher oT strains famale male strains famale male tested tested

no change JlO ch,inge no change 9 dies in sex 3 in sex in sex

expression expression expressi(ln

5 dies

no l:hange nll change ,1 dies 2 in sex in sex

expression, expression

(Vg) dies 01.\" ~L)

Suggested by 'l'_"'ZIM.\'S case of translocation IL%IMD'l'o attempted to induce translocation between Wand one of the autosome~ bearing noticeable gene Zebra. The procedure of his experiment is illustrated in IV"-6.

In Dreier to find the location of female determining genes on W chromo_,.--.". ~,r--...

some, Tazima obtained complex translocation Z-''''{· 'vV· +1'.pS", which is probably ,..--.... ,,--..,.

a product of crossing over between Z and W in a W.+ 1,.psu/Z,od female (IV-I) IV-7). If this assumption is correct, W chromosome which has lost a part

48 T. Yokoyama

IV -6. Experimental induction of translocation involving Wand an autosome

X-ray irradiation in pupal x

, stage

'? zebra

o zebra

normal 1311)

o

untreated

~O'I Q a

zebra od-transll1ccnt

aberrant (I)

oil iebra normal 8xO o zebru-od normal

I X

o normal

~tl

zehra

if zebra

(,

normal

(j normal

by crossing over still retains its female determining power (IV-7--11. He also obtained several mosaics and exceptional types [r0111 the

,.---....,.---.... ,.---.... Z+·W·+I'·ps!tfemaleas dissociation product by X-raying. The mosaic has

,.---.... a _1_ 11 .pSa constitution and simultaneously was a gynandromorph, which was

,.---....,.---.... ,.---.... considered to be Z'I. w· -J-!l.psa to start with, but the mosaicism was brought

,.---....,.---.... ,.--..... about by the elimination of w. +p .pStL or Z'I-. W parts in somatic cells (IV-7-2).


IV-7. Experiments to determine the location of female determining genes DO W chromosome

(11 rnduction of complex translocation

:{~~W !-n __ ~Z

p - :;-...__ "'-= translocation 01 1I·11 to W ---.

~:; iIIr~ ==0 .P~x~

+0$ .,.fI od

.P . rmalI!mlI.

;,01 TO 'for} high temperature Ireatme"t

(2) Dissociation of complex chromosome by X-ray irradiation

1:~ //X.ral's iilII~ ./J ",ad = ~ lOd~

exp~cted left side dissociation

observed number 23917

= p·,Dd -------.. 9 .3

7

mid right side deletion dissociation

.t..a ~" other types

L1JIIJJCl mosaics for .P fr"·.ad I .p "".od .P ",. 'and ,00

T'? ~ 10 iJ Wl1ll

IV-9_ Functional differentiation among regions of the W chromosome

'·.Ir~~ x.jr~n - III -v Z Z 1lI III

Z Wll~.bra ~ III \ oJ ttan$lucentl ~

Z'I~~lu' .IIT .llD~· Will 7. III lIi Will (. rrrwm z Z IllWIll 7. Z III III

zebra od ~ ~ebl'a od !f. I

(non. lethal strain) (lethal strain) .;lIe normal q

49

50 T. Yokoyama

Fig. IV-S shows gynandromorphism in a gonad, obtained in a complicated mosaic female, which probably originat.ed from partial elimination of complex translocated chromosome involving W. In one of the follicles of a testis of this female a mass of oogonial cells is seen which is developing independently from the surrounding spermatocytes, bu!: transitory forms towards the opposite

sex are hardly visible. As for the functional clifferentiation among the regions of W chromosome,

the following exhibition 'vvere made. When a certain part oJ W chromosome exists in ZW or ZZ, constitution lethal effect is seen either in t.he female or

in the male. a) (W) ZZ is lethal, while (W)WZ is viable (IL,.,.sIMoTn) (IV-D).

,.-..._ ".--.... ".--.... b) ZI-.( ).+l'.pS", ZW is lethal, while Z-I-.( ).+)'./;8" is viable (TAZIMA).

Here (W) or ( ) means a part of chromosome originated from W. The former still contains female genes while the latter does not retain female determining genes. Hence, the female determining genes do 110t seem to he distributed evenly over the whole W chromosome but considered to be localized in a certain section.

IV-S. Gynan(lromorpilism in u gonml of a dis~m:iate(l type-mosaic induced by X·ray irr,ldialioll

.' ._

~ ~. I~':

I :'~ "., t;,,,, ; .. .';:1;

:.~

'.

" :/

Explanation of photomicrograph

, l

'~ ~ ' , ,,,.,,,1'

If~~ , /

I .' J

jl:'~ ':'1 '1 ~i'!, .,-: ~

This picture shows gynandromorphism of a gonad of a complicated mosaic female. probably originated from an egg in which elimination of complex translocated chromo-some, involving 'vV. occurred partially. •

In one of follicles of a testis of tflis female a mass of o(jgollial cells which are developing inclepenclently fr0111 the surrounding spermatocytes il> seen, but tn\nsitory forms towards the opposite sex are hardly visible. Y. TAZIMA


The mechanism of sex determination in the silkworm IS different from that in Lymanlria dispar, which was thoroughly studied by GOLDSCHMIDT.

Contrary to Lymantria with its abundance of inter!lexes, no real intersexcs have been discovered in Bombyx, but all abnormal ones in relation to sex are found to be gynandromorph.

52

V. Induced Mutations lLlld th.e Practical Application

A mutation was induced in the silkworm for the first time by HJ\SIMOTO

11929), treating eggs and pupae with high tempei-ature, X-rays, centrifugal

force, etc. Afterwards numerous investigators obtained various mutants by

using various methods. The silkworm has been proved to be a material in which mutations are able to be easily induced and 32 induced IIlutants have alteady been reported.

1. Mutability in relattQtl to vario\.\s agents. I) X-rays

The. sensitivity to and mutability by X-ray irradiation of the silkworm are different according to the developmental stage and the sex. The change

of sensitivity to X-rays of female and male germ-cells is shown ill LD50 curve

in V-l, which shows that female is more sensitive than male in pupal stage (TA,ZIMA, 1951). Sensitivity of X·ray~ varies also remarkably according to the developmental stage of germ-cells. Figure V-2 shows lhat male germ,cells are quite sensitive to X-rays before meiosis, but they become fairly resistant after meiosis. The difference of mutability in various stages of gametogenesis

was studied by TAZIMA in specific lod and was made clear Lhat mutability

is highest just before the first metaphase of maturation divLlion both in spermatocyte ancl oocyte, while in gonia mutability remains at rather low level of frE!quency (V -3).

V-1. Sensith'ity to X-ray of male and female germ-cells ill v~rious developmental stage

2'

~ 15

~ - ~ ~lll ~

na~e to kill 50% oi embryO)

~

~ .... '.

5 6 7 pUI'~tiun ngc o( pJ.fcnt pupae

10 dOl}' old emergence

De...-eh:'I'~~wl~\.\.t ~{ t.~~ • ..:\!{i'=> \<;>. ~~~il;tt $tlg't!

BOth It ~

~ D > 0

.: ~ : t1 ~, _, o. ~

~ ~Q , 6

age of parent pupae

Silkworm Genetics Illustratecl

V -2, X·ray; Change uf ;;en~itivity of male germ·cells before and after meiosis

%

10

tn:utr:tl <tge and f~TliIity

1st fl'cding

/ ,/ ,

~Og~r ' ,: , . , . . . .

agc of the 5th in~itilr larva

DI.H'clopmcllt of germ-cdt" in !:ith stadium

'>Pl'rm3l11gonia Sllcrm.atocyte spermatid

50

100 m:nuring

100

53

V-8. X·ray; Mutability of germ·cells in various developmcntal stages clocs rate: 8t4 1 per minute

V-4. X-ray; Difference in sensitivity and mutability among different strains

nI:ll'k,~d luti: !L'~ and ch

femal" GO','

I

. . I

. " I

I

d~)· (lId

fi 100

t' GO

~ ~ 40

" '0

20

2.U

1.0

Mortality

rb ,/ 9 ·1.5 days afler pupation

:,/~ 3 dar old, 5th inst?

",.~Y-"'"'''''''l~ , ............. . 1(}()(J 30(1() TOW r

;;,,{i_ (II immediately before emergence

-t-/ 1000 30UO

dosis

54 T. Yokoyama

A remarkable difference of sensitivity to X-rays was also found among the various mutarit strains of silkworm (T AZIMA, 1955) (V-4).

2) High teniperature When newly laid eggs are treated with high temperature (40'C.) for one

hour, various abnormal worms are to be obtained at a remarkably high frequency. Among the abnormal worms there are mosaics, polyploids and those expressing reressive characteristics w11ich are in non-treatc(l casc covcred by the allelic dominant. TAZIMA compared the frequency of those abnormals according to the age of eggs treated, and obtained the results as sh6wn in

V-5. The appearance of recessives in this case are presumably clue to the ab

normal fertilization of sperm nuclei, i. e, fertilization betwc'en two sperm nuclei without necessitating egg nucleus in c()njugation. This was explained genetically by HASIMO'fO (1934) in a very skilful way as shown in V-5,

V -5. High temperature

It's effuctivent::ss and specificity! l3y keeping newly !ai(l eggs at I[O'C., 1 hour, 80 nlHny mosaicH.

recessives and polyploic1s are yielded!

Frequency of appearance (Tuzima '47)

Elucidatiun of dispermic merugony (Hasirnoto ':H)

e c~· +/+.+/+~ :'l/(llud.F.~»:o E~ls+' I "'" s

recessive~ 40"C ] hr ;;;osaics

E"~ctcd +/od

EKP~+

Exreptjoocils od/oil ~

EKP/EKP E"'/t- +/+ o all 0 1 : 2 : I

3) Centrifugal force By centrifuging 0-3 hour old eggs, polyploids are easily obtained, as a

result of the disturbance of the behavior of polar nuclei. This was first studies by TANAKA and KAWAGUCHI (1932) and later by KAWAGUCHI (1934, '35, '36) in detail (V-6) ,


V-G. Centrifugal Force

By centrifuzing 0-3 hour old eggs lots of polyploids are obtainable PM+lpl'J? xPS+lfr~+ 1; (centrifuged)

expected

4n (21. 6.%') 3n (67.7.%') 2n (10.7%)

Mechanism of 3n formation

1 Egg+l Polar body+1 Sperm

(1) PM+/V/PS+ (2) p,1[+/p,1[_~/ps+

(3) pY/pr/ps+

4) Colchicine

1 Egg+25perms

(4) pl"/p' + /P~+ (5) pJl/P'+/frS+

55

HIROBE (1939) succeeded in obtainin!t polyploid silkworms by painting dilute (0.05-0.496) colchicine solution on tWe surface of the eggs within 25 hours after being laid. Polyploid individuals were obtained as mixoploids with diploid and polyploid parts (V-7).

V -7. Polyploid silkworms induced by colchicine treatment of eggs

colchicine hatchability number of moths which (%) C.%') laid polyploid eggs

U.4 \l 19 .. ______ , __ .. c_.~_

U 'J 46 6

0.1 C'J J~ 3

U.05 72 4

control go 0 -._-.-._- -_-.. __ .. _

Polyploid individuals can easily be obtained by colchicine (0.U5-0.4.%') treatment. of eggs within 25 hours after laid. But, progeny test shows that these: polyploids are mixoploid, containing diploid and polyploid eggs in an ovary, T. HIROBE

5) Nitrogen mustard and other chemicals Nitrogen mustard is also known to be effective inducing mosaics and de

ficiencies in the silkworm. Nitromine and N-bis alanine are also effective for this purpose (NAKAO et aI, 1952). NAKAO (1954) also tried to examine the protective action of cysteine and mercaptoethyl amine, which had been ,known to

56 T. Yokoyama

V-B. Li,;l.~ of incluCl)c\ lllutanls

New gene mutations

Symbol Mlltation

Ac Abnormal l:lJ]'sekt

A/) Abnormal appdih'

As Abnurmal Sl~glllel1l.

Dr Brow11 (lIlurking)

Bu Burnt

Df Dominant llwarf

Eel/, Additiollal t.:rL:SL:~'llh

E-Lg Epislal.ic g(Clle [u 1·[,g

I·cr

I·Lg

nUl

MI)

pll

j) I.

PS(l:.!

S'/IlU

,<:)lP

SI

Spc

Crcsn)nl suppressur

Inhibilul' of Lg

Light gray

mLlstache a

Mustadw b

Venlral striped

Light cn~scenL

Sable (marking)

Sable ~ (Illarl·:ing)

Pale ~;tripl'Ll

Dominant small C.'m Wh i lc·t hora~, s t r i )led

SeCOll!\ stripc.c\

Supernumerary legs

Speckj~c1

PIWl1ulYPl)

Ll'thal

Ldhal

Lethal

Lethal

Lethal

Ldhal

Ldhal

i\Ll'!lllli)alliL~d by j'S" ddiciellt

lIypm;l.at k to ",/,

Lethal

Ll'lhal

Ldhal, ([e.ficiency, semi sterile, esp. l;

Leihal, hii~ltly ;;l'crill'.

Author

Aruga '3D

'Tazi lna "!i2

i\ruga '.1:]

Axuga '~-I~J

i\ruga ',1:1

C(/ of SU7.uki '8H lIasiilwll) '41

"'iiI' uf T;dw~aki '47

TatilllOl '·1:\

Sak:ll.a '·1:1

Taka~;aki '·17

Pf (II' Chikushi '3~

Tazi llla ,,).,

Takasaki '·17

S-fI ut Takasaki ',17

J\.ruga '4:-3

Tazim<l '!i2

Swi Short \ving Chrul1lllsumal alJl'.rralilill Takasaki '117

Swl Swollen (!Judy shape) Lethal jJsw oj' Takasaki '47

Tb Transparent back Lethal i\rllga '·111

Vestigial Sex-linked lcihal

ya yellow antenna Tanaka '4:~

1. Fragmentation

Rusty

od-mottling

os-mottling

S-mottJing

M-mottling

Ze-mottling

2. Deficiency

loch.

II-ch.

III-ch.

etc.

3. Inversion

pv

Sa

4_ Duplication


V-IO. Lists of induced mutants

Chromosomal aberrations

Kawaguchi

Hasimoto, Aruga, Tazima

Morohoshi, Tazima

Tanaka, Kogure, Aruga, Takasaki _-,----_.- ~ .. ~- "'"----._ ... --.

Aruga

Aruga,

Tazima

Kogure, Takasaki, Tazima

Aruga

Tanaka

Tazima

DS-2, DS-3, paM-I, paS-I Aruga

TI02 Tazima

5. Attachment

rfh G. Translocation

pi-mottled

T CPS)

T (PJ!)

T (Ze)

T (II-W)

Takasaki

Tazima

._---T (III-W)

T (X-W)

T (VI-XIV)

Hasimoto

Kawaguchi

Aruga

Aruga - .. _ ~_, _-_-._0·'- .. _. ____________ .. ____ ._,,,_. _____ . __ _

Tazima

Hasimoto

Tazima

Itikawa

57

58 T. Yokoyama

be effective in other organisms against radiation effect. His res\.!lts, however, were negative. A fairly positive result was obtained by him only with pyna

cryptal yellow (V-8).

v-s. Nitrogen mustard [lnd other chemicals

Effective for inducing mutations Ni trogen mustard (Nakao '!i[))

Nitromi ne (mcthy!-bis·i'l·chlurllcLhyl'>1ml ne N'llxitle) (Nakao et al. '52)

/ClI"--CH2-~Cl CII'J-N"

' I "CII"-CI-I2-Cl o

Nitrogen mustard alanine (N·bis-,l dtlorocthyl·alaninc) (Nakao ct al. '52)

/CH2-CH~--,Cl HOOC--CH-W

I "'-CH2--CIl"--Cl CHi!

Protective against the mlltagenic action oj' radiatiun pynacryptol yellow YICS (Nakao '5,1) lllcrcaptocthyl amine No (Nakao et al. '54) cy~tcille No ( )

Gene mutations and chromosomal aberrations induced artiftcial1y in the silkworm are listed in V-9 and V-1U.

The summarized 1 ist of spontaneous ane! induced mutatiuns is shown in V-12.

V-12. Frequcncy of spontaneous und illduced mutations

charac:lers kinds

I, I ~---- pupa &'1 WllUll~ ;cmbryu, larva ! C.UCUUll I lIlul It ' lif(~

tutals

spuntan(!otls duminants f) 1-7* I () <g) Hi Il ,1 92 !

recessi ves H1+S* 1 :22 GO 2 11 1 lUi

induced dominants ,1 1 U 21 0 1 1 27 I recessives () 5

toLals 6 240 ~--.---' .. ~---.. --

* genes concerning to hibernation

An interesting mutant is especially worth mentioning. TAZIMA (UJ53) obtained 32 mutant silkworms among 1,126,414 individuals, the parent, either female or male, of which were treated with X-rays. The mutants took the leaf of beet and other plants as food which normal worms never did (V-lla).


They show abnormality in the structure of maxilla, especially in the sensory hairs on the lobe, which is supposed to be the food selecting organ. It is, however, difficult to rear the mutants with leaves other than mulberry

throughout whole larval life probably due to the inadequate constitution of leaf. V-Ub shows cocoons spun by the mutant individuals fed on leaves of RyuzetslIsai, Soy bean and red been etc. during the 5th stage. Selection on

the frequency of appearance of mutant individuals gave remarkably positive result as is sbown in V-ll.

V-l1 (a) Larvae, the mutants, are eating the leaves of Alianthus g{andulosa :and beet

V-ll (b) Cocoons spun by the mut,tnt "abnormal appetite" individuals

60 T. Yokoyama

year

1952

1953

V-ll. X-ray; Induced mutation in food preference

number of larvae fecl on beet leaves number of ;lctuul FI 2nd i 3rcl '1th rill!

examined instal' I instal' instal' instal' no. of elllel'g~d

I I11U tants

937, 916 f) II 5 ri 11

198,498 3S;1 :cllJ (ill :-H.l:1 :H

mutant

HC:"lUII nf ~L'Jcctirln 1nr 'I alJnol'lllal apPl'litc"

Y. TAZIMA

V-18. Folypluidy

a) Effective agents fur imlLle'ing pulypluidy 1. Centrifugal force Tanaka ct Kawaguchi ':~2

2, Cilichicine lIirolJe ';J9 :~, High temperature tn~atll\CJl1:

,1. Mo~aic gene

lJ) From ecunomic sland [JUill\:

Uasimuto ':'],1 llm;imulu ':H

II enlarges cldl size hul' cietTI!a:;e:; cell lIumbl:r It's 1101 pl'llIuising frOIll t't'l)lll)lI1i<: stand puiut

freq. of appearance

O. 001

0.183 ------_._--_

cell size ploidy weight of

]Jupa

I 11 lImher

1,t sllcrlll<lto- i

L',y te C\OO I

211 1. (i,j em"

311

4n

2. Polyploidy

:-ii I k-gl<llld cell

0.77 mm

1. 03

1. 4!J g

1. riO

. ' . silk·gland

l,'ell

(iHU. ::1

I

370.0

E. KAWAGUCHI '36

Though colchicine is also effective in inducing polyploids in the silkworm as in pther animals and plants, far more effectual method in the silkworm is centrifugal force (TANAKA and KAWAGUCHI, 1932) and high temperature treat-


ment of newly laid eggs (H.'\.SIMOTO, 1934). Polyploids as well as mosaics and gynandromorphs arc also easily induced by the action of a recessive mosaic gene rno ~H.'\.SIMOTO, ElLU) (V-13\.

In tripi'oid and tetraploid silkworms, the cell size is larger but the number of cells is smaller than diploid. Consequently the silk productivity is not expected to be increased (KAWAGUCHI, 1937).

3. Practical application of induced chromosome mutation The powerful s2x-determining function of the W chromosome was appUed

for practical purposes by TAZIMA. As in Japan an the farmers rear PI hybrid, the discrimination of sexes is a very important procedure in the commercial egg production. Usually the sexes are discriminated by the tiny spots on the ventral side of the growt1 larva. T AZIMA obtained a strain in which a fragment of chromosome II, which carries dominant! genes for noticeable character is attached to the W chromosome. In this strain, all marked larvae are female, while all non-marked larvae are male; thus the sexes are easily separated.

The females of this strain, however, were not hardy enough owing to the )lyperploidy of the translocated part. TAZIMA attempted to remove this defect

V -l-J.. OrigimLl sable transll1. (W+I1.p8<') ,

62 T. Y O[\0YUlll<l

V-V1. Practical applicaliull of lral1s1ucalioll in the silkwurm (1)

p~f+ 1" +(111 IV __

z_ ......

~ <1>'1

\V~:. z.".,""""

1-';[

\\r,Ptl'f] (\v. ; 11 i r 'F:" ! .'

X'LI\' Irl'ill!~I~:~~1 "

"~,,,d' rt:"I.,(,1. •

::f/'~ \V~_ '.\I'-~"""'" ZIU~ .-. ..,..,. "_..,.",,

M-strain

W~("",,""''l

II ,I, , ,

\\1\'\ 1 I"liJli:lrily ill1pr()v~)d tYIll:

x.ri.lY~(~lllt"11

IV_ ....... z=_ z~ -l"zEZ:'tCiI-\\1. : j1 i J' i ",1 ',I jJ i J'oJ ,Il

111 I I'rld ','

Pre:,ulIlcll ell ['dlil',J.>' I illL' (011,,1 rud i. III

W....".....;".- IV""""";;_ z= ....... '1.= ....... w-Z= .......

~ ~

I-;f. 1lI~:t;\!J1i,,:,,: of \V·l' :;[ r.dn

(prilllHi1.v ilJJprtJH:d lYJlll)

:-1 r~

~;I ..1 ·711:

r.1 hI 1/"", ndY:,

)l;IY'iil~~n '-~-' .~----- -'---

jJ! ill1i!lT f;tJl'oflriaql r1f1f!Il;d l)'lll~~~ I Yl1eH t YI!l"~

CllG

Improvement finished Trilnsferred heronftcr to brt:cd pnH:tical raC'..:~ by eros~iing to tJu(JulHf r;~o~s

Y. TAZIMA

Silkworm Genetics 1llustrated 63

so as to be used for commercial purposes. After repeated irradiation of Xrays, he succeeded in eliminating the superfluous part of chromosome II, leaving only a small fraction of the chromosome where marking gene located. Thus the strain became to be utilized commercially (V-14l.

The eggs laid (W+"'~)

T. Yokoyama

TAZIMA wa;; not content with this, but took another ~lt:ep forward. He intended to make it pOl;sible to separate female alld male egg;; by the same principle, because the male worm ]1r()clL1ce~ cOlllparati vdy larger amount of silk than the female. By utili;.:ing same procedure as us~'d hy HASIMOTO (IV-6) he could induce translocation in which W chrumosome was tagged with a fraction of X-chromosome involving the dominant gene to white egg color IV-I4).

In this strain females come out of the Illack eggs while ll1ales hatch from the white eggs. lIe alRo c1evj~ecl, in cooperation with an engineer, an autountie ~cxing machine for eggs of thnsl~ strains with photoelectric tubes, which enables to discard less useful [emale eggs bc[un.' halchillg' IV-IS, V-IG).

I

V 15 Practical application of tran:;locatiol1 in the silkworm (2) SL~x-tliscrill1ina(ion uf eggs hy tlw color

, \\' c::=J .... I~l-:-'i=l

, ,

\\~r::-'-J~ ,. r::::=:.:. 1::::=1

\\'~IJ~ll I.~ WIll

WL":..:._.=",_/c:::=I_

1L:.:":~,J,C,,_1/l-:;::";2/£:Tl ',,1. • , , WC_;--'l :'_' I Ic::::::.J C~·~:::, ?l. -;,1/'-_',1---' ,', . '},·::.:-.-l

I.) "'/ • (I I

r.Jllp1'r

(.'I"",II",I"IJI.!

Z['_=--~l [-._"1

i:f-::-:-:-l r_--

'--'

w c=::rda l"=~J i t=:~:1 l-~ 2c::...J c=:J?c::=:It::=:l

• ~ lV" .) 11',

\\,11111

6.7 U

Y. TAZIMA

'I~


V-16 ea) Automatic sexing machine for the eggs

V-16 (b) Reverse side view of_the_machine

Y. TAZIMA

66 T. Yokoyama

VI. Mosaies

TOYAMA 119(0) 111"8t descrihed a mosaic silkworm in detail. Aflerward a

recessive gene 1/1(1 was founc! by GOJ.I>SCIlMIDT & KATsuru (137) in the presence of which mosaics Hfl~ easily obtained. Recently the mechanism by which various kinds of mosaics and ll1()ttlings come nut has been explained

and the method of ohtaining mosaics has been improved to a rcmarkable ex

tent contributing much to the advancement of silkwol"ln genetics. For this exhibition, the following arrangements arc made to show:

1. Mosaic clue to 11U1 gcne. VI~-l Mosaicism and ,C("ynal1dr()morphi~m.

KATSUKf anel AKIYAMA Wl37) [ound a heritable mosaic strain in which a

number of mosaics lor hoLh :--lOmatic and sexual ·characters· appeared as they were mixed with the normal im;ed" in Olle batch, l\ATSUKI worked further

with GOl,nc;cIIMlllT (1 D~7--19:~ i'l on a mock of occurrence of the mosaicism

genetically and cytologically. The mosaid~m is causc.d by one recessive gene

!}lO possessed by mother insed. In cytological observations of the strain

homozygous for mo, it was founel that 1 wo egg' Iluclei appear in egg plasma

and each of them was fel"tili;wd with a sperm nucleus. Therefore, it was

assumed that each fertilyzec1 nucleus might develop into each side of insect

body. Somatic mosaics:are expected to OCCUI" ill one of the crosses: J. mo, A/a><a/({; 2.1110, il/Ic<!l/({; ::. 1J!u,a/a:: .1/a (el alld (( represent some allelic

genic symbols), Further, mo, is a rel:cs~;ive gene I>y Ilat Ufe, hut acts as dominant in mUltiplied conditioll, as ~provecl by H~SIMOTO \l\),11), in tetraploid

VI-l Mo"ail:imn and p;ynandroJl1urphism

nil!' tn a Gl'ne tU{)

.... " , . L EI!~~ Tllldl'll', ,n\1] Plll;11 1111111' ;II'(~ _. Hd.ltl'r:d 111"'"li .. " f(,,. p.v C(Hljlq';lli'd u·;,ll 'il'I'fm rl"'I','(·II\·,._-I\· :\1111 fl . ,III';,~{, h\' mo in q~\: p1.I!;Ill~ o( "1(1 :.\ rcllll

,1. Bilil\(,'ral mo~:tic; for 1. ,Ifill +

K. KATSUKI & R GULDSCHMIDT


VI--2 Mosaics of markings

+Pcil-P' C/.

p~ +r:h _p~ ell

pZe_p+Z, I-I. CI!IKUSlil

VI-3 f Mosaic of silkgland color

I T ~ • 0 11W,P"+Y'PY,C p+'IP+r, C

Gl mottling

mOl mosaic gene pll, moricaud pattern p, DJai~ ]" yellow blood

+ Y, cDIorles3 blood C, deep yellow cocoon

"'. @.Osho\\'ingbltJod color

67

M. HARIZUKA

Though the blood color genes arc clearly identified from those of the cocoon colors as shown in other figs., the Yl!llow blood gene, Y, which enable to be permeable the intestinal mucosa to carotenoids into blood circulation, was proved to be also concerned in permeability of silkgland wall to the pigments from blood into silkgland,

fiR T. Yokoyama

fcmale JIIo/mo/1/l() I which produced mosaic offspring in spite of posscssing a dominant gene +.

VI-2 Mosaics of some larval markings. VHl Mosaic of silkglancl color.

y, yellow blood, and I 1', eolorless, eontrol lhe permeability of the intestinal mllcosa to caroLenoic1s and are in linkage relation with JJ M, llloricaud pattern. Mosaics in the silkgland Wl'n~ obtained in the ~:rOflS, mo, P~cl/PYxP-I-, all of which showed nlOsaieisl1l also in larval markings, JIM and j), and were pale yellow in blood color, i.e., illlernlt'diale betweell 1r

and +. In mosaic silkglands there were two kinds of c('tls, yellow and colorless. This indicates that Yand _IX, which control the' permeallility of intestinal mucosa to C~l1'otenoicls, arc also possible to control that of tile silkgland (llAIHZtJI(A 1940, 1948).

~. Mottling due to the chromosolllal fragllll'ntaLiol1. Sl~veral strains of 1ll0tttl~d-transI11('el1t \wn' ohtail1(!cl by treating with x

rays Llw pupae' heicroxygolls for normal line! iranslUCl'nt genes. As the chromosomal fragment carrying a normal g('I1(' located on the Z chromosome is deleted in certain cells of epidermis and otbel' organs, so tho allelic recessive translL1cent gene exprc'sscs its action, while other cells when' no such deletion occurs show normal appearance, c()nsl~ql\ently making the pattern" mottling" (VI-8).

VI-8 Pleiotropic function of od genc' The od-mot[lec1-transluclmt (OIl"'I) larva charactt'rizl'c1 hy the mosaicism of

normal and translu(,ent skin is due to the eliminatilln in sO!l1atogenesis of the fragnwnl carrying 1".1 gene. 1n this llIlltUl'c1-lransll1cl~1l1 larva vitally stained with neutral reel, all of the ()rgans andt i~slll~s of ('C(oclel'llllll origin· ·C'pidennls,

Vl-H I'lvintrupic fUllc! ion !lr lid gVIU'

del1wm;tratvd liy vit:li st;lillill.I~·

nUll t I~·tl, t ril n~IHl~l!nt

SIUII!efi whh 11I'utl';11 rt:d

prothof{\clf.' uland

H. AkUOA


silk glands, Malpighian tubules, prothorasic gland, hypo-stigmatic glandules, sali vary glands, ocnocytes, and others--were stained in mosaic pattern, whereas those of mesodermal and enclodermal origins were stained homogeneously, This fact shows that ad gene expresses its action in the cells of almost all

VI-5 (a) S-mottled due to the elimination of the fragment carrying P' gene

Irre~ulJ,r mO~jlic<l.

sC;'l1,reg:il.:d (rom muttled-'tripod

II CHuwsm

VI-ri (b) MOltling due to elimination of chromosome

S~mo'hled !jtralnli, A, whit~

f).lJtdu;o~·!;L',iJnty; U. Jnll!fnJel.lilllc;

C, num~'rllllS; D. liilutcral mosaic

A B D

I~

In\egumllnt of S·mottled wllitL' piltch~a scanty

Hdl(l\'hHlT III th~ :iupl)rnUmerary chrom()son1(! (S)

during- till' milluration division

li, !.;upernuIl1Qrary chrommwmt!

A c

t, TAKAsAKI

70 T. Yll!(Oyalllll

organs and tissues of cl'ioclerl11al origin of the silkworm larvn, and the cells of organs and tissues originated [rom ectoderm have lhe same cytoplasmic characterisLics necessary for tlw expre~sion of ()d-oily gene (AIWGA, H142) (VI-B).

Vl-ri Tile Si7.l~ nnd Illlmher~ of whitl~ palcllt'~ in t.he intL'gllml~nl., distl"iiJull'ci

in th(~ examil1l'd an'll fWO llllit~ (While [latr1H.'~·H<::lnIY)

Frl.'lllltmcy (If the (dimillHI ion o( the :;upl:nILlllll'rary cl!ronwsomc in I.(L'I'1\1 ('('lls lIf rliffl!)"cnt sexes

(White palrhe~.s('anty)

5U

.iI

11\1

ih'I'I',I/t{l' \'-'.lhll"" 01 the

I.:limln.u lUll Ih'rL'l.!llla~~

....... \;t 1 ~ t U ~II ~

,.../ .............. , - ,', l"i.i.t,II'J:i ' •

............... ' . .....

II -~-Tr~"-n" .... :!ri:'I~·::.!j'~a.· '_""";:""'l'-

Vl-!i Elimilwlin\l Ill' fragnlt,'111

Fruqllul]cil'!{ (If l'lirnilltlli(l1l of tilt' SlIIWl'l1l1IIH.'l'1II'Y dll'OlllO:ionw,

jJN fraf\llH'IlI, in lilt! dil'fl'l'l'lll ('llroln(I~;l\lIl:t1 ('UIlHtiluliolH;.

(Sm) and (]'), ,("l'I'I':1111 t'!II'Otlln:;ullws Ill'oclll('('(] Ity hr·t'nkilll{.off or till' 2nd l'1l I'l)m(\~al11\('; I I, till! wlio!(' ~!Ild rhrOllHtS(ll1It',

l'111'0 1) 1(\:;( Illlal ('ow;L i t (( t inn

(Sm) / t I / I I -(Sm)/(Sm)/ I 1/1 I -(Sm)/( n/ I I - -

-(Sm)/(Sm)/( nl I I - -(Sm)/ I I -(Sm)/(Y)/(l') -

ttV(lcaR(' vnlu('s of t lll~ ('I i nti Ilal inn

11l'1'('1'111 :t!!;l'

'I'

.U'i.O."()

!I.D

1).0

Il,O :t .[

T. TAKASAI\l


A few kinds of striped-mottled were obtained by treating with X-rays the pupae heteroqgolls for striped marking (ll) anc! normal. This kind of mutant is characterized by the appearance of numerous white patches in the black marking and is clue to the elimination of the fragment carrying

the dominant gene jJ" on the .second chromosome in the epidermis, making the appearance of allelle recessive gene /_]I. The freq Llency of elimination of the chromosomal fragment is different according to the struclme and behavior of chromosome. It is high when the chromosome does not exist in pair, as in trisomic zygote (Vl-G, VI-G, VI-7),

VI-7 Elimination of chromosome in trisomic zygote

Elimation of the whule 21ld chromosolllc during gamcl.ogellush; in trisomic ;lygule!:l, jJ'/ Y / I-''"!

sex cl!mllHlliLJll percentage of each

of 8 chroinosllllws total

p' y f"fJa!

2.11% 4. ()~b !J. ~)(% 8.9%

7. u 8. 1 7.1 22.2

Trii:iomic mmmics and their ]}rogcnic~

•• 11 .. @i~~~

3. Mottling due to a mutable gene.

P' 32

o

progenies

Y ;.oal

132 144

142 142

T. TAltASAI<!

This mottling is clue lo the mutabilily 11'0111 nor111al to oily of oat gene located on the second chromosome, and i~ characterized, in appearance, by the irregular distribution of normal and oily parts of illtegumel1t~ mixed in one individual (VI-9, VI-i0) (TAKASAKI 1940).

T. Yokoyama

VI~H Mottling ell\(! to mutable !~IJIlC

Hereditary <:hallge~; in tllt~ mutability lIr oat gelw and its direction

",,/ (II

('lIlhl ~u

lollo,t)

V-ll1 Maturnal illllul'llC(~ of inhiilitor, Ie (Ill till) lIlutabilily lit' fI(lt gene

I' .

F I


VII. Devel()p~ental Genetics

TOYAMA was a pioneer in embryological study, as well as in the field of genetical study of silkworm. His paper (1902) is even now, referred to as one of the most valuable reports on slll{worm embryology.

The non-c1iapausing egg of the silkworm hatches about 10 days after the deposition at 25·C. showing no pigmentation of the serosa (VII-I), while the diapausing egg begins to show the characteristic pigmentation of the serosa in about one day after the deposition except for the case of white egg mutants. The serosal pigmentation is completed in 3-'1 clays, and the egg color is determined by this pigmentation incombil1utiol1 with colors of the chorion and of the yolk.

VIl-l Embryonic development of the non-hibernating, egg lit 25·C.

/

The silkworm egg is deposited at the metaphase of the first maturation division (reductional), and the ferlilization takes place in the egg in about two hours after the deposition. Unfertilized eggs deposited by non-mated females or dissected out from the ovarian tubes of virgin female moths can be induced to develop parthenogenetically by high temperature treatments

which are known to cause a union of two haploid cleavage nuclei or formation of the restitution nucleus in the eggs (SATO 1934, '42) (VII-G), The high

74 T. Yokoyama

temperature treatment of the eggs newly laiel by ordinarily mated moths also causes the androgenesis (so-called" merogony") (IIASIMOTO H)29) (VII-G, VII-7, VII-8J,

The formation of egg color mosaics which is often observed in the eggs treated with high temperature within one hour arter the deposition is due to the participation of cleavage nuclei derived from a union of two sperm nuclei in the embryonic development. The mmmic paUern of eye color, when it

appears in the silkworm llwlh, is always antero-pmltcrior stripes parallel to the body axis, in contrast to the mottling lype which is usual in Drosoplzila (TAZIMA 1942, KOYA.MA l!)!'i()) (VlI· 51.

The germ cells clilIerentiate t!Jemsl!lves 1'1'0111 the blastoderm cells in a definite region on the ventral side of t.lw egg. The periphl'ral plasm which is specially destined for the place uf germ cdl differentiation, sLlch as the poslerior llolar plasm in Dipteran and Culeopteran inst!cls, can not be distinguished morphologically in Lhe silkworm, thoug-h a pru~wmJltive region of the germ cell differc.ntiali(l\1 hm; h\~\'n rOI1~hly nmplled tm tht~ ventral side o( the egg by cauteritmtioll experiments (VJ[·~, V 1I. ,1). For I he formation of the gonad, the germ eel I:> thus clifi"erenliated, lllllst he receivt!cl illLo the genital ridges which have tht~ origin, independent of the gm'lll cells, in the coelomic sacs at the (i·-9th segments Ill' tlle embryo IVII :1).

In the silkworm, many lUlll atiol1s wb iell cause 111 a ]formatiull in various organs or have lc1hal efl'l~d have hl!en discovere(l, :supplying' L1sdul materials for the developmenlal studies. E-alleJes arc a group which draws Ollr special attention and on whit-ll many studies have been nmclc g'iving' very interesting results. f\ remarkable characteristic of H alleles is the Yael that lhey show pleiotrupic actioJl on variolls t isslles am! organs (Jf edudD1'11utl origin, 'Inc! cause morpholugical as well as physiological c1is(l1"(krs in c\evdopmcnl. This pleiotropic al'lioll of the genes sLlggests that their ad ion is com:cl'llcd in the cell differentiatioll at an early stage of Llw embryonic devululllllcnL It seems that each 01' these alleles ads with its own [lotc'IlLial in a definite c!irection (TAK1\.5J\Kl HHD) (V[I·~Hi, Vll·-17). A dcfcd or thl'. ).!;onad rormutiun in the homozygous UN embryo may iJe cited a~ all example of these Slllclk!-l (ITIKAWA

19M, MIYA 1955). At the germ banel !-ltag'c, the dit"[ercutiaLiOll of germ cells proceeds normally in the EN I EN embryo as in the l1ol"malulle. The EN gene, however, begins befol"G long to affect clctenninatlull of tlw body segments, and it makes the abdominal segmcnts develop into the ones resembling thoracic segments (VIl-,lJ, VII-H). It also inhibits f()rmation or Lhc genital ridges which appear at tbe (l·-9th segments in the normal umbryo receiving the germ cells. Owing to the detect of the genital ridge formation, in the EN I EN embryo, the gonad formation can not be initiated, and ge.rm cells remain free amidst the mesoclerm cells and finally degenerate (VII--15).


The kidney egg is a maternally inherited recessive character. That is, a female homozygous for ki gene lays only kidney-shaped eggs which die without hatching because ot a lack of the mesoderm formation (VII-12).

In the silkworm there are many characters, the expressions of which are affected by environniental factors during embryonic development as seen in the change of volt in ism by the effects of temperature and light (see the section of Physiological Genetics). Here cited are the l11ultilunar marking and the mons tar larva (VII-9, VII-lO).

VII-ga A multilunar marking appears in the presence of gene L, but the num

ber and localities of the lunar patterns are influenced by other genes and environmental conditions.

111 the lowest extremity (2L), the patterns appear in the fifth and the eighth segments where there are markings in the normal pattern worm (2L).

In the highest (7L), the lunar pattern appears in every abdominal segment, from the fourth to the tenth.

There are several intermediates between the two extremities ..

VII-9a The variety of m1l1tilunar

®0®®®®®®ct + * + *

Black and red -I- ligures show ordinary types of the multilunar. These types can be obtained as almost completcly stabilized oncs. The blue tigured ones * are very rare types, and it seems probable that 5 and G are genetically comparable with G (red) and 7 re!'lpectively. T. HmoBE

VII-9b Therc are two centers as the lunar pattern occurs, the fifth and the eighth

segment. The lunar pattern appears primarily in two 'center segments, next comes

that of the sixth, the seventh, the fourth, the ninth and the tcnth segment in order. However, the order between the fourth and the ninth-tenth segments. is sometimes altered.

The patterns in the segments aecorciing to the above mentioned order are highly heritable, while those on the segments in different order are scarcely carried over to the offsprings.

76 T, Yokoyama

vrr~9b Order of manifestation

10 1\ 12 13

Crit ic:;a I period for determining manifestHtion

9 r L. ___ _ ~ J.

10

I 15 ~o dll),' (al 15"(;) 30 I ; ----,.. l I .. ~_~ __ :_ ... ____ ~_. ____ .~

egg Jllylnll . A II c H1nwtukinC;ih. hatch

U 1, l'

Crilh."nl 111~rtml in dtHMmlnlng t. is H .. Ll~ whil~ tIHI~i(, r~lr II", hcrilnbl(!

nHJllstar II nnJ the \'ullif1h.nl lIr!! A .. C .111<1 J.~ ... H, r('~Il~dl~'l~Jy

T, Ih.n~~

The manife~tatit)n. \$ the ml.lltihmar paUm:n i\:\ inHu(mccd by the incubation temperature, 'rhe lower tlw temperature (within the range between 15° and 28°C,) do t.he more llaltcrn\:\ appear (VIH)(:.\,

The critical period when the 1ll1111ber of' paU(ll'llH is lIlm;C affecLed is between the sixlh ane! tlte fifteenlh day of incubatioll al I fi"C,

VlI-$\.: Chall).(e~ II [ lIlflni [t'slaLiun

by inculmt.itlll·lell\Ill'.I'alUrt:

L,llUllIif L·hl'l~ro ..•..

1 HIROB£

For 1!llt'il'cll'(1 IIi\U1'l: refer to VII~

!)n, wltilL' whilv ligures iii) and ((i) cor· rl'~il)(Jlld to lil) lind (Ii) ill VII-911,

+ + J\l'l'lIWS hl'l WI'l'lJ cil'l'l,"!\ ,,\lllW the cl!allge of t. lit! Hum her of lhe lunar IHIII.L'rn according to I.he gCllcticl\l

comilil.lItilllllln wlJlI <If, to liw illcuba· t ion tl)llI[ll!ratuJ:e,


VII-9c When the eggs heterozygous in L gene are incubated under a low tern·

perature (15·C), the manifestation of lunar pattern is nearly the same as that of homozygous ones incubated under a high temperature (25°C).

There are, however, two exceptional cases in which the influence of the incubation temperature is not observed, i. e. 5L, and 7L in VII-9c.

VII-IO

The manifestation of the monster, mse-II, is different according to the treatment of eggs. The appearance is very rare in the eggs treated with hydrochloric acid soon after laying (VII-lOa). In the hibernating eggs there is a high frequency of appearance (VII-lOg).

Besides, many experiments were carried out on the occurrence of mse-II using the eggs treated after the hyclrochlorizatiol1-refrigeration method or the refrigeration-hydrochlorization method as well as eggs treated after other methods, obtaining the following c(:mclttsion: if the treatment in which the hatching is more difficult, the more frequent beco111es the appearance of abnormal worms. However, it was found that refrigeration has no direct in· tluence upon the occurrence of the monsters.

VII-IO Changes in manifestation of the monllter (mse-II) gene dLle to hatching method

eRg laying ~c\d.. hatch a.bpnpoe',mread" a treated With acid ISh t .. ~a.atmcl\t

'0011 nftc" lilYlng 0.;; 'K)>e-------12 days--lncub.t'Qn (25'C)----M almo'l none

b rcf.rdigl-Crrc~,tlcd "{ter ~~~40h~lu//HffiM#m-!A'l/.rMM25 clays%'J,w(.(!j)/)////(.I'lffff?1J;W...-il days.... very few aCI ~ .. mcnt ~

c alr(ct ~tcdrc(Wrlith ac!d a.-40h -MlWffffJJm//J,//4mIV)ljllJ.26rla}'s!4@J/J)jJffuJJj/jj)/m/JJIJJ~""_11 days..... few er gcratlOn ...,-

" 00--72h __",wff/fo,w)/;/plm'i/:21 days~11 days-tO' more abundant

f refrigerated

g kepl Ut:dO t d" ()4-35da)'s~natural tcmf" re(rig.ratlon(S·C) naturn "m ILIon (25·'C)·· ·iu<J;;YsL-=-~90d'YS~12d.YS'" many

Manife~tations of this monsler are different in grade among different strains, so the pcrcentagc of abnormal:; can not be decided, But i.t is noticeable that the abnormals can hardly be obtained by the ordinary hat· ching l11ethod (a)

Physiological analysis of lethal actions will be an interesting problem in future as. hinted by a study 011 the lethal non-hibernating egg (VII-ll).

VII-ll The lethal non-hibernating, !-n, is a recessive single Mendelian gene, seg

regating 3: 1 in one batch in F 2• The eggs homozygous in l-n die around the blastokinesis stage of the embryo.

78 T. Yokuyama

Ii.' Ii! " '" g '" ~ .~ m ::;.

! ~ 0. U

cl'

VII-ll Difference in 02·tlplake anel development between normal and lethal l1(1n·hilJeratillg' (I-II) eggs

200

100

VII-4 Maps of the pre~L1l1lpl i Vl~ I'q.r,iOll of tlw egg at tlw cJl!(lVage hla~\lud(!l'Il1 stage.

1. ventral view

a. v~ntral view

... ,·~T~:·, ",~'~_rr,.,.u&f"

. ~_, ".:.:" \!~~i,.~~~~;i~: _._ .'

-"":'~f=~" '~~l~'"

.u~I-"·"'/ "

""n,II.1 ,.,1. ~

2. lut (.!ral vil'w

.1. cnH,ti ~uction

~ x lUO:.:~ /1.5 :;.~: genital region 00'

0",; -:;:::-;'1(100 ·"";·~t.O nW~;(IIJcl'mal rt:gi(lll tlU'

T. TAltAMI & I';. ~ll\'1\


When eggs are treated with hydrochloric acid, normal ones hatch in about 10 days after the treatment (A), while I-It eggs die after about one month's slow development showing less 02-uptake (B). When eggs are kept at 25°C. without the acid treatment, normal ones enter the cliapause showing little O2

consumption (D), while l-n eggs whose O2 uptake is somewhat higher than normal, show slow development before death, reaching the blastokinesis stage in about 70 clays.

The yolk segmentation begins in about one day after the deposition, and the yolk material is divided into small spherules, the yolk cells, each including one or more yolk nuclei. As all the yolk nuclei are derived from the same cleavage nucleus from which the nuclei of embryonic cells come, the embryo has an intimate relationship to the yolk cells, but not to the yolk material itself which is of maternal origin. The interaction between" the embryo and the yolk is one of our problems to be solved, and the androgenesis (" merogony") and in vitro culture of embryos are used, in addition to the formerly used reciprocal cross, as the new techniques in this field.

VII-2 Differentiation of the geml cells

, . ,~;IjJI//.,. " ,: "'/i"~'~~"'"

3. Cross section of nn 18 hours old embryo

L Cross section oC a 16 hours old egg, showin!( th" ,ogrogation of the germ cdls [rom the ((crm b:lnci

-"" ',,, 4. Cross section DC a 21 hours ~i ,,'-';1\ old embryo

2. Longitudinal scclion DC a 15 hours old egg

5 .. Cross section ;'24"'hours old cmbr),o, the germ cell. separate completely from the germ baud, and, .rc ~nclosed by the somatic ccl Is- presumptive mesodermal cells

1<. M,YA

so T. Yokoyama

Finally, it is worth saying a few words about the results obtained in the field of experimental embryology. The si Ik worm egg belongs to so"called mosaic (non-regulative) type, and a defect due to partial killing of its embryo

nic area can hardly be fLlled up by regulation, giving rise a partial embryo. The presumptive regions of organ pl'irnodia have b(~Cll roughly mapped on

the surface of the egg (VII 4). VII-2 DIfferentiation of germ cells (K. MIY/I).

In the sill<wol'tn, as in the Dipteran and Coleopteran insects, determination·

of the germ cell seems t.o be brought aboul by entrance of some cleavage nuclei into a dcftniLe region of the periplmnll, only difference bdng that this region is not located at. or near the posterior pole of lhe egg but in a definite part on the ventral sick Dirfl~rentiaiion o[ the gel'lll cell lakes place shortly

after the formation or the germ band, and a group of cells which have been

differentiated into germ cell~ invaginate inward from tlH! germ band.

VlI-a F(1rmulinn tlf the gonad

1. Cr,,~s seL'lion lhrullllh lhe Hlh ~~gml'Ilt of a nu hUll I'H old C:lllhryo

4. LUllgit udillal ~Il'l"liun lIf ~hc 7-~llh St'glHcnl~ uf a 72 holt n, old l'mbryo !-\howinn the gl'nitul forti

2. Crm:i~; ~l~(.'l ion~ uC a GO !wnnl uld embryo lhruugh llll' Uth (1\) and the Htll (Il) s"~nll'tlls showing' lhat the f(cnltnl rid~e I!xtl,tld, Inward and l'nclt.]~iL'~; till! Hl'l'lll celb

fi. L.ongitudinal scdillJl of the 7-Sth Se!(ments "f it 78 hout'u "Id l'mbn'o showing lH,tdllal eontraclion of lh~ gl'nil,tL coru

3. Cross sc·ct'i~;;~·;ta GG hours old embryo through lhe ~lh (A) :lnd the 9th (B) scgmcnl~ showing sL'paratlon of the genital ridge from the coelomic sac and formation o( the gonad llrimodium

K. MIl'A


VII-3 Formation of the gonad (K MIYA).

The gonad formation begins with the differentiation of genital ridges in the coelomic sacs in the 3rsI-6th abdominal segments. These genital ridges extend inside toward the germ cells, roll back to enclose the cells, and then segregate from the coelomic sacs to form the gonad anlage separately in each segment. Next, these gonad anlages connect successively to form a pilir of cord-like tissues (genital cord) which later contract toward the 5th abdominal segment, forming the gonads.

VII-5 Differentiation of the compound eye. There is a well-known fact that the mosaic pattern of eye color, when it

appears in the silkworm meith, is always antero-posterior stripes parallel to the body axis, in contrast to the mottling type in Drosophila. This can be explained by the direction of the differentiation observed in the imaginal bud (N. KOYAMA).

VII-5 The pattern of eye color mo~aic appears as al1tero·posterior stripes ia the silkworm moth

N. KoYAMA

VII-6 Doubling of the chroll'/-osome number in the egg developed by artiti.cial parthenogenesis ..

In the unfertilized egg artificially activated after laying, the reduction division proceeds normally, but conjugation of the two haploid daughter nuclei

82 T. Yokuyama

resulted frol11 the ihirc1l11ito~i~ of len lake~ place giving riHe to a single cleavage lludeus which seems to dc'velo]) into 11 diploic! individual. On the contrary, when unferlili7.cd eggs dissected out from the mother's ovarian tube are artificially activated, doubling or the chromosome llmnber is accomplished by formation of the restitution nucleus Ill. SA.'I'OI.

VII-G Duplication of ehrOm()~(lI11l' number in art ilielal partheJlogenesis

ChriJmO:ICHm\~i u( 11 tdp!o'ld In'brill hCl{wccr'I a Il'! r;1ploll1 1(,!I1II1L' ami iI -tUpluid rtw.le

1. CunJUI1Rlhlt\ nf till: l\\'11 II"u~hlM l1ud~i, n'~u.dtl'd frmn thl! third lIlill1~h '" lin ilf!llrdnllr udival(!11 I."!~:~ dl~Il.\\)ill.·d h~' (l vlndn Imil~l~

~ 2. A rc;\tltutlun nul'iclith

In tin l'l-!l!: (U~\W·tll·t1 lIut IWnI 11h~ O\'Url'lll tulle Iwiort.' tll'rlU~ltiuh nud lu;tirutlJu Wilh hiUh tl'mp~·rulu:rl'. nJflt'.tlninij' ~H IIni"'ld~nl ilfld J lJlvi.llclll dll'llOlUill)mc~

3 r':quIltluII41 dlvluioll 01 IIII' p".,litntillu nw'll'n,.. IlIfl1lllliol 1I111y ulle IHllur h(jil~'

5. 'II dlrtllllll'\nl1ll~!i ill tl IlIiuHlrr "'IIP r ITIII 1 I.IL' ... , , ~

VIf. 7 Ar(ilicial llarll11'llogC't1l'~·;js ill. I {.<\SI MtI'J'(1l.

lj, H,I 1 hr!lrthl~IHlllt'~ HI <I

~I..~"ulldury '1I'l,'rIlUJiwqtl!

l'arllwl1llgenesh, h, Illml to I)('l'llr s[HlIllalH'lllmly ill till' ~;ilkwurtl1, while it is rather easy III Ill' in<illl'l'cl by artilkial In'aln}('llt or \'g~ts with hot water. The silkwor!11H ckvdo[ll'cl by arl.ilkial parlll('IHJg·('!ll'~·;js art' (til' salllL' in gC110-

V((-t i\rlili<-i:ti parlh,·ulI.l';t'IIV::i!;

I. Unfcrtllilc~ '~g. loid by virgin mothHj not trCt~lc:d

:!. Ullfl!l'lili"':cll (.'lUpi 1!lId hy virgin moth\! in .!Ic"'~:rnl uaym nnd If(mlcd wllh hUl Wi.1tcr

~t 1"l'rliliJ:~d ('I.o.t\'1 1;i!iJ hy mUlad funmillb irl II h'w hllurli

ll. llNl'MOT<I


type to the female parent, that is, when a mother is heterozygollS for some genes, the parthenogenetically obtained progeny are also heterozygolls for the same gencs, and are mostly diploid females with some exceptional tetraploid and mixoploid i11divicluals. The body of the mixoplont consists of both diploid and tetraploid parts. As far as artificial parthenogenesis by heat treatment is cone l1l"l1ed, eggs dissected out of the ovary at the end of pupal stage or eggs of emergecl moths, and those cleposited by virgin moths are the same in potential in parthenogenesis.

VIl,-8 Androgenesis (union of two sperm nuclei in the egg) (H. SATO).

A union of two sperm nuclei in a silkworm egg exposed to a high tempt:,'ature soon after the deposition. The resulted nucleus develops into a diploid individual without normal fertilization (so-called /I merogony").

VII-8 Merogony

Union of the two sperm nllclei in the Rilkworm egg eXJlosed to high temperature at the time of oviposition.

The rc~u I tcd nucleus develops withoL! l fertilization of lhl' egg nucleus. I-I. SATO

VII-12 Development of Iddney egg. A genetical character, kidney, is a recessive mutant affecting the shape

of the ep,"g and causing death of the embryo formed within. In the kidneyshaped egg laid by homozygous hi females. the mesoderm formation can not be observed, while differentiation of the ectodermal organs proceeds inhar

moniously (K. SUZUKI and M. Icr·IIMARu).

VII-13, 14 E-gene group (N. I-rIKAWA).

Generally speaking, the occurrence of extra markings and su pernumerary legs in the silkworm larva is related to the E-gene group. Of this group, 15

genes are known at present, all of which having the locus (0.0) on the VIchromosome. These genes are all dominant to the normal.

EN and EO(/" among the rest, are very suitable genes for study of developmental genetics. Embryos homozygous for EN or Eca die at the later stage

84 T, Yokoyama

V[l-l~ Embryonic dl'vl!iopnwnl of Llw kidney l)gg

I. + nnd iii ORR"

am; amnion doc: den.nor.tlng .011 for: lorm.llon coli Ip: log·lIke prot ••• mt: main lrachanl lnmk "": oral cell pn i Pr~t\fn8I1c portion Mer: aerol"\. lit: IIllama

SUI): Siup.rnoes()ph~geal

t: ~~~~'11!~ n Ihp: lI,orock port Ion ye: yolk coli

;' /~ ~: ,n uo,' It' ~;! "" ,,~ ... ",

r' \

2. A (ully ~rllwn J' Ill' cmhn'o

r-"'-'--

38. Crml" iiCl'licm

,hrouRh Ihe

procophdli<' parl

511. Longitudlnnl 8'~llun Qr the prucclllml k llart

LongitudInal action uf a G dnys old Iti t~mbryo .. "--.... ~.,

..,~.-..._-

'''"

(D. Cro.. ..cllon lhrouuh lh. mlddl. I1lU\ l'( the Ilbdohll)O

GA. LonHllutlin~1

~wl'tlon ut II Y dn~'8

uld ~i om~rl'u

flC. Crmm 5D, 1Il'('t!<'n through In.val-tlnnthHI till! uhdolllCI1 ur !.iliMma ill

r,E. Furn"'t lun

{II thl' mllin

trnl.'hcul trunk thl~ ahd.ll'ncn

4C. CrOtlll "",,11011 ,hrouRh lh.

pro •• ph nile pori

7. Longitudinal ..eetlan 01. 12 doys old

vucu()I"U~d ki embryc>

.110;· .. ···' ..

..

K !-iUlllKl & M. 1~~II1MARU

of embryonic ckvel()jlll1cnt without ~h()wing any l-\iHIl of hlal-\(oldnesis, TIle appendages, hristles, spirac1e~ all(1 t nll'lw;tt, ()f llH' 1 st"ll! h ll()(ly sl'gments in the EN/EN embryo are of thl~ forms rt~scmb1ing tllo~e Il(' llw thoracic segment in the normal embryo, while ~piracles and t r<lcllt!Ut' are rudimentary, while no abdominal appendages arc seen in the l,:r',,/ RI'" embryo, Moreover, gonads can not be observed at all in either EN/EN or E"" / Eri" embryo. According to MIYA (1955), the EN gene does not affect normal differentiation of the germ cells, but development of the genital ridge.


Embryos homozygous for Nc (located at 1.4 on the VI-chromosome) lack some thoracic segments, and die at the later part of embryonic stage.

All of the EN, EGa and Nc genes in homozygous condition cause abnormal differentiation of the thoracic and abdominal segments.

Genes of the E group have not a true allelic relation one another. ITlKAWA has found that recombination occurs between EGd and EN", obtaining some EGa EN"/+EN individuals in the offspring of EGd EN"/++ 9 XEN/+(O). These individuals had many supernumerary appendages on abdominal segments. It seems that these individuals have abnormalities in the chromosomes as a result of crossing over occurred in the E locu$.

VII-l3 Embryonic abnormalities in E·mutants After ahout 3-4

day" InCUbatlon,\ the embryos can be distlngldghQd

I;!ach other by Lholr characteristic; nlmormalities

Fully grown

embryos

+(+ Nurmal

£"(EN Thorllx·1 ike

ab<lomlnul5cgmenu, gonad absent, no

blastoklnesl~

.....

U I

Abdomlnol leg. and gonad nlH;lcnt, 00

lJllIstokinl!sls

VII-14 Extra legs in the pupa and moth (EGrl ENe lEN illdivic1ual~)

1. pUpD. 2. Plath .,' ~

1~·!lrJE.'{tlel\· Individuals, obtillncd 1]$ a

recombiontion of E~nllellc genes,

havt! rllllny p(lir~ or cxlra legs

00 the ubdomen N, i'l'IKAW'"

N. ITIKAWA

86 T. Y"kllyanw

VII.15a J\bs<"l1cc of the gonad in 1 he 1,'N j [~'N eml>ryo m:. MIYA).

Tile gonad formation in tile ~ilkworm i~ divided into twu ~tcps, the Ol1e is c1i1Tenmtiatiol1 of germ cells at the germ band slage, and the other is formation or the gcnita I ridge at II\(' HJlPenclngl~ formation ~tage. The absence or the gonad, which is one of the eiwraclerh;lics or the ENjJ.,'N embryo, is

explained before.

1. Cl!J:,'; "('1'111/11 lhl'IIIIIdl III~' :J. r",t,:, ./'1110" Ilulilluh ,II,! /JIll

lith ',"V,IILI'lit .-1 11'1'; 11"'11", \l1')!JlLt'1i1 01 .I 11(, hULII",tid I~W/f·.W ult! JIIIJ'1H1l "/uh,'v'l Ii 'rill /·1111,1 .... , TIll' ~:"lIll.d IHI~TI' I', IllIt 1:,11, ,\It:{'H,h''oI,d II\' III,' ,'1'1[. jolllll'li .1I1t1W'IIHII'II·, l"I'lIl.dll

'" 11h' 1~1'IIlI,d li,ll~' allil,11t' )~qHad pl1!JllldlLlln ", '''11111'11.

I.IIILJ~i I lid/II ill ·,,','lltlll "I til,' ):II;llIJ:1J ';"}:I/11'II1 1)/ ;( /:'

hl'III" .1\,1 IIPlilial 1'lItil1'\'11

(;"1111 ,.'11" \"1'.[ 111'1' .1II1"UI'

,I ... 1IH"'\I,d"III1,d .. "II,

I. I.II"V,L\HlIiUi,j ',1'1 (jnll lie lit,' l\~qlh ''''':III.'1I1~i .. I ,I 'l:~ lUlurti lilt! 1-.'.\1""'\ "111111\'11, l"I'l'llI tl'lh ,", I'·, 'I,·,'I\' :unnUH" III!' !l/I" II!!'" 11/," ,db .I' III liv. :!.

V[r~l!ib Studies Oil tfie' l~' p~;l'lldllalll'lk ,I';l'!ll'~; ill till' silkworm (M. TS1IJl'J'Al.

Crossi I1g (lve'r 1>('t \\'l~l'\1 I,: l/' a n<1 1','Jd> was r(llLnd iTSllJ IT \ '!i:l, '!iil I, When male heterozygou8 for 1,,'1/ and /,;1.'" rrum tIll' allt'lk ~wril's llH'lIt iOlll' (\ ahove wcn~ lllated with norlllal f('malt-s, a ve'r!, small llUllllll'r oj' individuals with the ciscoJlflguratioll p;ellotope Hfl H"J'/ I +. "'(I1'(! ol)taifH'd. TIll'c;" larvae have a new phenotype which was only t'xpt'l'tt'd alllOlli; 1lll' I)[Ts)lring~ ()r FII nncl RK1', where there occurred J'(!l'oillhi nati()n. The J'l'I'o1lliJinal iOll illd i viduals wefe

characterized hy the pre~-K~l1l'e or ('xlra-alldol1linal IV.I'S (lr til(' first and second ahdominal segments a~ well as Ill' eXlra-semilullar paUl'rllS Oil the lir~t abdominal segment. They arc tllLW ea"ily clistingllishC'C1 from tlw Hli I j I E 1

(P

larvae. A few larvae with genotype Hli and KjJ/ I larvae always appear in the

cross + x II KP;'-I- + obviously by recombination,

Silkwotm Genetics Illustrated 87

Furthermore, from the cross between Ell ane! EN", Ell and EAt", Ell and E'u" and between Ell and EN, a very small number of recombinants can be obtained.

From the facts presented above, it is clear that genes belonging to the E-series behave as complex loci. This E complex loci may be called by the term, "E region". It consists of several genes with similar effects arranged in close sequence at the end of chromosome VI.

VII-15b The E p;;eudoallelic genes in the silkworm

+/+

M. TSUJITA

VIT--IG The role of E-allclic genes in the embryonic development (T. TAKA

SAKI).

The most rcmarkahle characteristics of E-allelic genes are that they show pleiotropic action 011 several tissues and organs of ectodermal origin, and also t.hey manifest morphological as well as physiological disorders in the development. Studies on the pleiotropic aciioll show that these allelic genes are possihly concerned in early cell differentiation of embryos. As far external character~ arc concerned, the disorder is most remarkable in the crescent markings ane! in the prolcgs. ·What is noticeable is not the abnormalities themselves manifestcd in specific body segments of an individual, but the mode of manifeslation of gene actions which has special connection with the body axis. When morphological characters are comparee! between E-mutants and normals, it is evident that the corresponding character appears with some shirting- of the place of expression along the body axis in these mutants. Each character has an expression center in a segment where the expression is the 1110St frequent in occurrence becoming lower toward the anterior. or poster lor direction.

88 T. 'Yokoyamd

It is assumed by TAKARAl<I that each of the R-genes has a cel'tttiil actiOil potential to make the expression part shift toward the anterior, or posteri~F clir·ediol1. For example, the action of l~'u" begins to appear at the first ab-" dominal segment and spreads posteriorly, I1Htking crescent markings appear 011 the third segment in addition to the sc!concl segment which is a normal area of the expressioll, and also making the character which appears on the fourth segment shift to the [tfth. Thus the star spots normally appearing 011 the fifth segment often duplicale in Lhe sixth and seventh segments, The direction of action is definitc! [or each gene, and cetLain genes act in the posterior direction (Eli" :.~), whi Ie others in the reverse direction (E11'~:). Morc" over, there are some genes which act inlhe poslerior direction on the dorsal side and in the anterior direction Ull the ventral side lEKJl,:::!.), and vice versa (Eyl~ ... ).

The action potential is not the same at different levels along the major axis of the embryo, Thc potential of pill is the highest in the fHth ahdominal segment, becoming lower in the next segm.cnt, so t.he absence of star-spots on the 11fih segment. is a stablo charader, whereas the extra-crescents un the third segment is variable in expression.

The direction and power of action are different in Jit~ •. , [i;D and Elip not only among thelll but also lJL~twl!ell till! dorsal al1(1 ventral sides of the same individual. The curves show the power of action in the thorax and the abdomen.

T. TAI~ASAKI


VII-17 Disturbance in segment formation by EGa and ED gene (T. TAKASAKI).

The EGa gene causes abnormal fusion of the fourth abdominal segment with the fifth, or the fifth with the sixth, the fifth abdominal segment being

VII-I7 Deformities in the segments (;au~ed by EGa and Ell genes lind mechanism of their formation

head .. " ....... A

thora. de {I ::: II'" ..

seginents III'" -1 .... 2 3

abdominal 4· ..

segments 5····

B C D E F G H

A-B: ECa/+, C-D: ED/-I-, E-G: EGa/ED, H; EGa/EKp

I

1: Ventral deformity rarely observed in Eca/EEp and EDIEKP

Changes in manifcstioll of deformity due to genotype

deformed segments genotype direction

of action I

I thoracic abdomiml1

i percentage of

deformities

Eca/+

Eli/+-

E1(1'/ -I-

EU" /R"

EcalEJ(Pi I I

I EIJ/EJ.:l'

1/+

---" ... ) (d)

~--- Cd)

(~---- (v)

.= (d)

----->- (cI) --+

~ (v)

(--; (d)

~ (v)

~ (d)

::::::; (v)

..

I I

I

IIl~1",2(d)

2 ~ 3 (v)

III '" 1 '" 2~ 3 ~ 'l~ 5 '" (j Ccl)

5",G(d)

2~ 3 (v)

III ~ 1 ~ 2 (d)

2~ 3 (v)

III - 1,..... 2 Cd)

total 110.

5895

2969

The p~reentagl! in appearance of deformities is affected to a great extent by coexistence with any other allelic gene. Cd) : dorsal, (v) : ventral sides, arrows directed to the right indicate tendency of posterior shifting, and vice versa.

T. TAKASAKI

90 T, Yokoyama

the center of the abnormality, while the HI} gene causes the similar fusio11 between the third thoracic segmcnt and the fin.;t abdominal segment, or between the first and the second abcltlminal segmenis, having the center of tht:! abnormality in the r1rst abdominal segment. In t11csl~ cases, the abnormal fusion is limited to the dorsal ~;ldc or the larvH, and docs not extend to the ventral side, Each gene, tillIS, has a c1efinitl.~ cxpression center where the gene action is the sl rtm,!{esl.

One of the 1110s1 inl(.~resLin,l!; featlH(~S of tlles(.' almurmalities is lhat the expression is influenced to Ll large exh~nt hy (,()!llhinat ion with 01 her }~'-al1elic genes, For inslance, Ilw alilwnnal illdividual~ increa~e in percenlage io fi,1396 in RO"(FD, anel d()crcas(~s to D,Ofi?il ill Hn"/HIII', in cOlllparison witll O,;ll?6 ill HOIl/HI, whilD it iH 5,~I:'o in HIl/I,'I, !O,riW'(i in },'Il/}.;r"', and in HlI/HI\I' it is llcarly tile same as in I~'II/ F I,

The body wall of silkworm larva has itc\ OrIglll in a dorsal L'xlention of the lateral margins or Ihe gl'rlll lmnd, 1 hal i~, thc cXlt~nsi()!~:-; frolll either side of the germ hand mCl'e and fu~e along 111(' llll~c!iall lilw lIll Ilw clorsal siele, forming a continuullS wall. Jr, thlTt'i'ore, titl' l'Xh'llSiullS are asynllndrical, it will l)l~ expected that th(' fusion Ull Ihe dorsal ~ide becollles iI regular, a part of the c:xtentioll n'l11ainiIJ,t:: fret' ill a sl'gillc'ni, or rll~>il\g with the extension in the neighhoring Sl'g'llICnt. I\'-allelic .f!,'<'lll'S SCVlll to ad in the course of wal! formatioll,

When twu aIle-lie gl.'IlCS in c()!llllinalilin arl' (lppw;ilv ill t'lwh direction of cell (1iffL~rcl1tiati(ln as in ,,"""//<.'II (,'.1, it is pm,siille tllat the uSYllll1lclry in extension, al'l~lJrdiJl.u:ly, irrl',l(ularily l)l'l'llllll'S lal'gl'r ill l'rl'qul!lll'Y, rCHlllting ill forlllal ion III' a largL'J' llul1l1wr (If abnllrmal individual,;, Un Ihl' ('(mLrary, if Iwo gcncs in C()mliitiatioll al'! ill tfll', ,;anl<'. dirl'l'lillll a~ ill 1,;('''//<.'11'1' ( :), [uwcr percentage ur alJIIUl'llla[ individuals will lie eXIll'l'!t'cl.

The rad thaI there is !10 J'l'llwrkali1l' diJll'rL'nl'c ill th(' on~LlrrCIlt:L~ of abnornlalitil~:\ betWl'l'll H"/HI anrl 1~'II/I,,'ll'l' (' _.1 l'an lil' l~x]llailll'd wilh the assllmption thaL E"I' h:lrdly inJlUL'Ill'l'S Ull' lin;! aiHloJ]]inal Sq,:'Il11'l]t ill which formatiun of tlw alJ1lo}'J1laiity is dUlllin<lil'(1 by "'II,

The shifting in 1)(I:.;itill11 and {'Xll'llsioll ill area (lr ahnoJ'malities, as ~cen

in J~u"/Io'JI, may be L~xplain('d hy tll(' asslllllptioll that the Sllm or ndioll putcntials of two allelic gc'nl~S which ad in oJlPo:.;ilv (tireci illns is largl~ enough to suppress completely th(' llurmal formatiul1,

Silkworm Genetics 11111strated 91

VIII. Physiological Gen~tics

Under this heading, voltinism, i. e·, the characteristics of the silkworm

related with the number of generations repeated in a year, molting and the

hormonal control of both are mentioned. These characters have practical significance in sericultun' and research interest and results in this field of

silkworm physiology characterizes one phase of Japanese biology. 1. Voltinisl11.

If genetically bivoltine eggs are incubated at 15"C. after the blastokinesis stage of embryo, the moths developed from the eggs lay non-hibernating eggs. If the eggs, however, incuhated above 2'1 DC., the moths lay hibenrnating eggs

(WATANABE EnS). The light also inOuenccs this characteristic, i. e., the long

day effect of more than Hj hours is comparable to a high temperature, the

daily illumination shorter than 12 hours to a low temperature (KOGURE and KOBA.YASHI 1928).

2. Molting. There arc in silkworm varieties tri- (lltJ3) and penta- (Mr.) molting ones

besides ordinary tetra- (_i_N) molting ones, and they make multiple alleles in

sLlch relalion as llfl>-i .11>M" on the VI-chromosome. The manifestation of the characteristic is affected by the rearing temperature and the nutrition; that is, a high temperature in the first and the second instars and good nutrition tend Lo diminish tIw number of molting.

S. Hormonal control of molting and voltinism.

BOUNIUOL (1 B3n) and KIIv~ \19~{~)) independently showed that the silkworm.

whose corpora albta are extirpated enters pupal stage without undergoing furLlwr larval molting.

FUKllnA (HJLiO) extended lhe study and conclucledlhat whether the silkworm

undergoes larval molting or pupation is delermined by the relative strength of the hormones of corpus allatum and prothuracic gland, where the corpus

allatul11 hormone restraining and the proliloracic hormone promoting meta

morphosis. IhsE(iAWA (E1Gl) and FUKUDA (H1Gl) independently proved that the secre

tion of the sub-oesophageal ganglion is the controlling factor in hibernation

of eggs. The hiilernating character of egg is also affected by certain kind

of chemicals sLlch as uranium nitrate (lLil.5F:GAWA 1943).

VIII-·1 Change in cliapal1se chantc1.er of eggs laid by the moth which de

veloped under different day-lengths and temperatures during egg

and larval stages. Motlls of bivoltine race are, as a rule, to produce 110n-diapause eggs at

the first generation and diapause eggs at the second generation under natural conditions. The nature of eggs are changeable with different day-length and

92 T. Yokoyama

temperature applied Lo the moth at various Hlages of life.

Both factors are most effective in lhe embryonic stage after blastokinesis in the course of incubation. DurinK the effective period, treated with complete dark of short-day illumination uncler J2 hOlIrs a clay, anc! a low temperature at 15°C., the female lllothH developed fnnll the eggs may produce nOll-diapuuse eggs. While trealed with a long-day illumination above 16-17 hours, and a high temperature of 25"C., they may produce diapause eggs.

In larval sLage, illumination and temperature are also effective in the same direction but wiLlt less degree than embryonic stage. In late larval and

in pup,!l· stage", on the contrary, a lower temperature below 20"C. may give a higher rate 01 c1iapau:>e egg producer ()f l1lolhH.

The threshold of percl:ption of light is O.OD r. c., Violet light, 350-510 m,LL wave length, has the same cJ'fect as white light, while a light over 550 m,LL wave length of orangt'.-ycllow has no rcspoll~e for lhe production of the diapause eggs (Temperature, WATANAun: 1DlD; light, [\OGUlm and KOBAYASHI 1928, K()GURE 1D:-33).

VIII-l Chang() ill lliupause charadur uf L'ggS

Through lht! effect of day.length and temp. UpOIl mullwrs (lJombyx nlfJl'i)

1. aiJove 21i"C.

illl1minated [or I(i hl"s.

illulll. [ur Hi hr~.

illulll. for 12 hrs.

.[. IJduw Iri"C.

i1lulll. fur 12 hrs.

larval i"ila).\l! I l"iwradc,l' or the 'I jlU pall molh treated as

Isl.-:II"<1 inslal'! .1I11-lilh ill~l. stagl' Ildl. I I , ,

I all lllOlhs lay regardk's:; of day·lellgth <llld l('III/). I t1iilpamw l'gg

: hakltes

illul1l. [ur Iii ill'S.

bduw ~()"C. aliuvl' 2H"C.

illulll. j"m 1~ hni.

regardlt.::,;:; of day·kngllt ami Il·lllll.

1

111m,t Illol.hs lay , diapausl' l'gg I haldwH

IllUsl. lllolhH lay Illll1(1 i apllUHU egg

! haldwH

all l1l0[J1S lay lIulldiaptlUHU ()gg IllltdlL!!;

M. KOGURg

VIlI-·2 DiscQvery of suboesophagcal ganglioll a~ the! tliapuusc center of the silkworm.

According to II. Kna;:AwA m)l1;l), it is easy to line! out according to Ehrlich's diazo reaction whether t he eggs arc desLined 10 grow 10 cl iapaLlse 01' llon-dlapause ones as early as they are within a pupal body. The reactioll was applied by HASEGAWA to his studies to find out the organs responsible for the determination of voltinisl11.

Silkworm C-enetics Illustrated 93

Firstly, immediately after pupation female pupa which had been determined to produce diapaLlse eggs was ligated at the level between the 6th and 7th abdominal segment as ovaries were located in the anterior part and then the posterior part was cut off. The eggs developed in the anterior part were of hibernating nature, showing that the segments posterior to the 6th abdominal segment had no relation to the determination of voltinism. Secondly, female pupae were ligatured immediately after pupation at the level between the 3rd and Lith abdominal segment as ovaries were located in the posterior part (Fig. 1). Eggs developed in the ovaries located in the posterior part were not influenced towards diapause. But if the ligation is not complete and there is a slight communication between the both parts, eggs may be

" "

'

I • r' J.J~. • S: III.

~ . . ..

,..;

bll ~

",i

bll ~

oj <l)

.!:: ..., u <l)

C C o u

~ <l)

b.Il .a p. o Ul <l)

o

u o

cr5 ..: .n <.0

on bll Ilil Ilil ri:; ~ ~ ~

T, Yokoynmll

affected towards diupausc, The results show thal lhe organ or organs to produce c1iapallse factor, iJ' jlreH(~nt,. \vollid not be localized in the posterior but in the anterior portion of silkworm pupa, Thirdly, decapitation"experiment was carried oul. Decapitalioll of newly pupated insects forced them to lay 110lNliapause eggs regardless uf wlwtller silkworlYls had been determined 10 yield cliapaL1sc or non-cliapaulle eggs by incubation l'OIH.litions, From this it wal:) inferred that the diapaLlsc (cuLer ,vollid be localml in or about the head,

/\. pupal ahdonwn isolated fro1ll lhoracic sl'gllwnts illll1wdialely after pupation' was clllllluyc:'cl to Lest a ruudion (If Sllml~ llt'gptl til" organs in question, It is call1'd "le!1L alxlunlCll" illig, I I, Eggs in t(':-it alldorllcn shall be neutral flll' diapausc. nature. TIll' Il':;L \\'a~; l".t1'l'it-cl out hy illlplalllat ion of organs or a sLl!1[ledccl org'<Ln togl'llll'r wilh pI'o[hOl'al'il' ,ldnnd \'vllicIt promote the different iaLiol1 or lIw It'st alldollH.'Il,

Implantation of each organ sllch as bruin. corpus allalull1, salivary gland and sulJot'sophageal gland aneI of various c()mhinal iOJIH of these organs gave no satisfadol'Y resulL. Only t 11<: implanl of ~;LLllIl('s()Jllla,lwttl gallglion, however, exertl'c] It certain erfed Oll lite gruwin.1.!; l'gp;S ill I he t(!st ahdolllen und made thCll! diallllUSL' egg (Figs. :: and ,[ S(;), Till' )'l'~iltllti ohtained wilh test abc1oIlH.!llS Wl~l'e [llen !1uhstan1iakcl hy l )'am;pl,llllill~; s\11)(ll'~;()plHtgcnl ).!;<lng;lia into the silkworm of llon-c1i:tpallSt~ Ilttlul'l', In JUri[), it. was l'l'vt'alcd lhat the ganglion plays an illljJ()J'lalll part in dl'kl'lllillllin,L\ diapltUHt' llalmc, liberating the diap<tusc factor,

Tlw larval gallg'lia ,L~rartl~cl inlo l'l'l'ipiunts \vill dl!vdop and will take a furm like thaL of illla~~il1al ganglia (Fig', :l).

Thl~ \.Y<m"jlhLl11 \ll' ~u\)\)\'''\)l)\i~\~;t';\\ ~;an~;\i\m \\m)'t lan'(\ \Fi~;", ',', <\1:H.\ '~SC,)

and molh (i'ip:, Ii, BSCI (L!lll'lillllS ill alll'rill,L', 1l1111-diapam;ill,l( l'ggS inlo diapctusing ()nc~;, Jiur[llt'l'Illll1'1', it h; ill1l'r('~;lill.L'; [hal I Ill' sulHll'sullhagcal .l~allg·lillll of

Tussal' silkwo),lll, .llll/w/'ll('([ j>('I'Il,1'i (Fip;, [iI, whit-Ii ('Ilk}'" inlu diaJlClUsL: in pupal forlll also (lOSSl'SSC'S [Ill' ahility lo l11al((: l'ggS ill' /lrllllhyx silkworm Idilernate.

In lD[i(), lL",sl':(;,\W,\. dist'uvC'rl'd Ihat tltl' diapuu~;(' I'al'lll1' origitmks in lhe suiluesllilhageal p;allglillll, The I'at'( was indl'lll'lIt Iy r!lulld hy :1, FUKUll.'\. and he has l'sLaillishucl a hyp()[ltl'sis that Imtill is (If primary ililpUrlanl'l: t.o conlrol the vulUnisl11, activating or SU[Jlll'l'!1sillg 1I1L' fLllll'1iOli of sul)(ll!!1opilagl'l.d ganglion by way uf cin:ul1l-ocsupitap,'l'al l'UllllL'C[ i ves (Fig. ::. DC I.

In all CaHC!1, huw(~ver, it is jusLiJiahle to say Uwl 111(' sulJocsophageal gan

glion liberates the diallau!1c fad or. Furthermore, Ilw transplantation of the gang'lion h~ l1Hecl tn ojlLain (IhllHlLlSI' l~gg:; or polyv()itine raCl~S, enabling iO

preserve the race wit hOL1 L repeal ing several gem.'rat iOlls \ I IJlSI':(;AW A 1 DfiO),

VlII-·3 The neurosecrct ion in the siI kworm, It was established by FUKUDA (1940--'44) thaL the larval molting <lnc1mcta-


morphosis of the silkworm are controlled by the balance between the hormones liberated fro111 the corpora allata and frol11 the prothoracic glands. But it has not yet been known that brain of the silkworm plays any role for molting and metamorphosis in this insect as well as others, for instance in Rhodnius prolixus (WIGGLI~SWORTH, Hl40-) and Piat)'samia cecropia (WILLIAMS, 1946-) ..

It is believed that the phenomena of the molting and the metamorphosis in various insects have been correlated with the neurosecretion of the lJrain (SCHA.RRER, 1 (54).

It has recently been reported by HASEGAWA (1951-) and FUKUDA (1951-) that the diapause of silkworm is controlled by the diapause factor secreted from the suboesophageal ganglion.

KOBAYASHI IW8 performed physiological and histological investigations on the brain, the subo;)sophageal ganglion and the corpus allatum during the metamorphosiH of ]iombyx 11/ori.

1. The hormunal function of the brain. When a pupa is extirpated its brain immediately after pupation, 110 im

aginal differentiation is obServed in the pupa. As it is in a cliapause-like state, the pupa is called" Dauer·pupa". If a fresh brain obtained from a normal pupa is implanted into the head of the" Dauer-pupa ", the latter becomes imago in 14-1 (l days after implantation.

The above results ~how that brain affects on the imaginal differentiation probably by secreting a hormone. It seems that the hormone secreted from brain initiates an imaginal differentiation affecting the prothoracic glands in

the silkworm (VIlI--J, Fig. 1).

2. The cytnhistolDgy of the neurosecretory cells in the brain. Several giant Cl~lls called neurosecretory ce1ls arc observed in both the

intercerebral is and the ]lrutocerebt1l111 in the hrain of the silkworm. A secretion liberated ['1'0111 the 1l(~urosecretory cells flows along two pathways; the Ol1e if; that [rom the l'ci [8 into corpus carc1iacul11 through the nervi corporis carclaci and I lIen l'('achl~s corpus allaLulll through the nervi corporis allati, and the other is thai from 1 ht' brain to the h[ood circulation through the cortex in the brain. The latter HCCI11S to be either a brain hormone or its precursor (VIII<l, Fig. ~~-ri).

3. The nenrmwcl'ctory cells in the fluboesollhageal ganglion. Suboesollhageal .l!;al1~di()ll contains also it number of neurosecretory cells,

larger than ~G/t in diameter, which differ in number according to incubation temperature, high temperature incubation giving larger number of neuro

secretory cell than low temperature incubation. The stainability of the neurosecretory cells in the ganglion during the

period from 1he spinnig time to 24-48 hours after pupation is weaker than those im.t11ediately after the 4th larval stage. B\.lt the cells from the 72nd

!:l6 T. Yokoyama

VIII-3 NCllrosl~crcl ion in tlw ~iJkw(lrlll (1)

l.]I,'Iolh uhlair1l'd b\' rl}imrdaIlL.ltion ,1,l.\rillll,\l 3nJ tillY ilfll..'l IJllpalion O. The numher of neurosecretory c(dl:-; in ~;l1h(le~(Jphageal ganglion of brain Intu the hCiltL tlf 1111

cl(!rnul pupa.

~J\flllali ~ ... ~ 1l.lj;,o ~ o

.... -:-: . t Ilai/Il : •• r. .. I

'';; TU:illl'd III "

'\ TIl'rtllid 10 liJY /) lIumrlap,llHil.'

• / t'HU~

2,BHtin ut i!!ntJ hour (If IVth illsuu' 5, Hru.ill ill Imrnl'llIalt~ly uller .~ NI:!2 11I~' di:trHIU\\~I' & ~ xl:Jl:1 I'm~'" •• : :.'(). _:~_ ,~.,_ 1--••• _ . .,..;..'

Utl)lItgtlllGI:l ..,r Il\()lh

·Iu lit) 711 NIIUIlIP(- III Cull')

Each pniltl rc)Jlre~l!11ts the llllm· bel' (II' \l('UI'llsNTetory cells in (11'1[' "l1hOl~Sllphil!!'l'nl gungliol1.

3.Bruin at 90th huur or Vlh imtlur

0: Tlw 111('al1 value of the number or 11t'l.\rtl~iet'l'etory cells.

M. KOBAYASHI

Fig. 1. Fig. :!.

Fig . . )

".

(Tlw l1l'lIrm,('cTd illn in Ille silkwOI'll1) [':xplnn:ll iOIl of Figure'".

A molh o]Jl:lillL'd by r('illlplanial ion or brain inlo IIH' IIl':ld or a "Dmw,' pupa ". Tlw I>r:lill lix('d al 111(' i:!nd hOllr or the 'lih in;;l:lr. An <lxh, from the neuro· t;eLTL'tory ct'll Itl lht~ Iwrvi t'orlH1rh; ('arioc] i,; Ilh;;('rvt'(j ill tIll) brain. TIll' brain lix('d nl 1 Ill' !llllh Iluur of tlw Gtll inslar. J\ largl~ vanwie about !ill,/I ill dianwll'I' is S(~l!ll ill till' cyloplasllI hi stailll'd tlt'(.·P with add fUl'hHin and tl\(' sPrl'l'lory ll!aI('rial>, IIow inlll nn :IXOII.

Fig .. l, TIll' Ilraill IiXl'c] on Ill" :lnI day ai"ll'r pupal ioll. Till' llt'llrtlSC'(TL'lmy Cl!l1;; arc lar,[(('r than thc' ('()nlllliln lIt'rvl' I'db (abollt 111," in dianll!II'r). A large vucuolc is S(,('11 ill I hI' cyloplasm.

Fig. G. An adult hrai 11 lixl'd inHllt!di:llely aftt!r '!lller)~(.'lli·(·. A Inr.l~·(' val'uoll' contain· ing agglutinate sulHitallt'l' i,; "I>,;ervaldt!.

Fig. Ii. The lIumher ur n('llrosec1't.~lory cdls ill sUhlH'sllpha.I.\I':d )';:lllgliol1 is compared bctwucn silkworm larvae Irl'ated so as tn lay c.hapallsl' l!!!,),(S and lhmw to lay Il()n·diapau~() egg~. At the last larval i11;;tar. l.he I'orlller had nwl'l! cells than the ]aLl_(!!'. In Ihis n!J~l'rvati(lll. nCl1l'llSl'l'l'dlll'Y n'll~; smallL,r Ihan ~fift in dia· meter we\'(~ not cOllnted.

hour after pupation to the previous day of the emergence are again deeply stained. The stainability of the cells in the moth again becomes weak with lapse of time. These facts suggest that the rise and fall of the stainahility of the cells has been cOllnected with a quantity of secretory material in the cells.


VIII-3 Neurosecretion in the silkworm (2)

1. Sul>(I(l8ophngen.l'ganglion 30. Corpus rlllptum nl 96th hour at th~ splnnln,g stage, of Vth \nstar.

8, SUbocflophngenl gnnsllnn l1. Corp~19 allMum "15th day immediately .(Ior 4th molting. niter pupation.

9, Corpus cnrdlpcum al 48th J2, Corpu$ tlJlallJm of moth J10l,lr aftor 3rd moltIng. lmmedlately aCLcr cmergcmce.

M. 1{OBAVASlll

Fig. 7. The suboesophageal ganglion fixed in SUSA'S fixing mixture and stained with Mi\LLORY'S at the spinning Blage. The neurosecretory cells in the ganglion arc stained cleep reel.

Fig. 8. The Hubocsophageal ganglion fixed in BOVIN's and stained with GOMORI'S

chrome-alum hacmatoxylin-phloxin immediately after the 4th molting. The large cells stained with huematoxylin are the neurosecretory cells.

Fig. 9. The corpus cardiacLll11 fixed at the ,18th hour after the 3rd molting. The neurosecretory materials is sttJfC~d in ,it (a phase contrast microscope).

Fig. 10. The corpus allatullI ilxed at tJle 96th hour Clf the 5th instaL The black globules in the nervi corporis nllati arc the neurosecretory material. The globu les arc also seen in a corpus allatum.

Fig. 11. The corpus allalull1 fixed on the 5th day after pupation. There are numerous vacuoles in cytoplasm of the corpus allatuJ11. It shows that secretory materil is elaborated in the cytoplasm of the corpus allatunl and secreted into the blood stream.

Fig. 12. The corpus allatum fixed immediately after emergence. It has many large vacuoles showing u degenerate state.

From these results, it seems that the diapause factor is secreted from the neurosecretory cells in the suboesophageal ganglion (VIII-3, Fig. 6-8).

4. The histo-physiology of the corpora allqta and the corpora cardiaca during the metamorphosis.

The secretory material originating in the brain is seen both in corpus caI'diacztm and in corpus a/tatum, as reported by BOUNHIOJ." et al. (1953). But

T. '( uiwyum<l

the phYHiological signillcance of this secrc10ry material Hccreted during the pl'riocl from lhe last instal" to the IlU pal stage, has nol yet beel1 known in the silkworm (Fig. ge'1~) (KOJIAYASIII 1!l5R).

VIlI- 11 Diagram showing the hormol1al mechanism of the determination of voltinism in the silkworm.

The diapause fad or which controls [he rlinpallse nature of silkworm eggs is secreted from the suboesophagC'al ganglion during the pupal Btage. The secretion is controlled hy the brain. The brain of the pupa destined to lay c1iapausc eggs has a function by which lIw subocsophagcal ganglion is stimulatt'c] to release the diall<lllSC fa('tor, and on the cOl1tntry lhe brain destined to lav non c1iapallse eggs inhil1ils to rc'lease it.

VIII-Ii Diagram ~il\llwin.l( Ilw 11IlnnollllI 1l1l'l'ilaniNI11 ,,(' the d~!lurminali()n (If v()llillism ill Ihl' >iilkwonn

SI;mul,lIi""

tlLld,,!' 1111' illl\llI'WI' Ill'

lilt' di;lP:IH','~ Llt'llIl'

t 1"'\II\lhaj!I'al

l'Utllll'l I i \"~

'VilliI'll! lilt' Illlhll'U,'" ot' Ihl' ,11.1P;lII',I' f.H 1111

vrrf·-[j On the nllc of pl'otliol'ilcic ,u,"lnnd and corpora ;dliltil on metamor· pbosis in llw silkworm.

Salivary glancb;, protllOrack .t.;Hnglia alld fat bud ie's lakt'll (lui [rom (i-day o1d larvae of the last instal' were transplant cd J't'Slll!('tivl,ly in[o u hody of a ~-day old larva of the last instar at tlll! \llh l)ody sl'gment. After about G days from implantation, it was ligalul"cd at two levels: 011C betwl!en the meso· thoracic and the postthoracic segment and the other between the gonadal and


postgonadal segments including the 9th body segment. 'the result was that the post gonadal segments implanted the prothoraclc gl!ijqd pupated, while those implanted another organs did not. The results show .. that prothoracic gland has the function to make the silkworm pupate. The :(pnction is exerted by me1jlns of some diffusible substance. An attempt to test the existence of the substance was made as follows; a matured larva was divided into two portions at a level between the 4th and the 5th body segment and both were

connected again with a glass tube. The experiment resulted in pupation of the both parts at the same time, These facts show that the communication of the substance from the prothoracic gland for pupation 'is not propagated through the nervous system but by means of diffusible substanc~.

Corpus allatum is also another important endocrine gland for metamorphosis of the silkworm. If corpora allata are taken out from body before the critical period for hormonal secretion.in each instar, the silkworm does not repeat larval molt but pupates, emerges a~cl lays eggs despite of, its iustar age. The experiments were carried' out llsh1g third, fourth and fifth instar larva.

VlII-5 On the role (If prothoracic gland and corpora allata 011 metamorphosis in the silkworm

:'1 ",":t,'" ' I"" '1:'· , 1· .... ' .. ti 2. Puplltion 1)( (11~ pUlOteriur rHln

1. lndul'lion uf pupaliuliin pmitiHiur of ffilltUrt; Inrva connected with p~\r'l1:i uf 1I}(l:llureci rn~L\1Te Illrvne ' anttr\rJf purl U)' !I glD.~s tube. by transplunlutioll 01 p!uthoradc gland

3. PUP;;I!! (If which

wruorll .dlalS! JUIV!! " hcen ~x(irp<\lt'u ill • ~ :lrd jn.'i[~r(lf:{n, 1/1 .lIh imitlJf (11111..1). In 5lh (Jr

I~!il in~lur (right).

. Cocoon 5 spu n by larvae openucd .as mentioned in fig, 3

5. MIJlha d~rivod frorp lhe three pupae shown in h,Q:, 3

U. Eggs l.:.lIlI by lhe lhr~c mo[h~ :;ho·wIJ in II!:!. 5

S. F'UKUDA

VIII-6 Parabiotic experiments on the hormonal mechanism in determination of embryonic and pupal cliapause.

100 T. Yukoyama

When two Bombyx females were connected at their heads, they emerged parabiotically and each of them could lle crossed with male and laid eggs. If two pupae different in nature (or c1iapallse, c1iapallse and non-diapause, wett'e chosen as each of the parahiotically uniting bodies, non-diapallse-egg-.prbctucing nature or one individual was chani!;ed to diapmlse-egg-producillg-nalure. This shows the transport of the c1iap[luse facto)' from one to the other.

J>/1i1osamia c:"I1.lhia, whose nature is to diapaLlse with pupal form, and P. ricini, which does not: c1iapause in any (orm are united parabiotically in pupal

slage. This procedure results in simultaneous emergence of both sides. It may he explained frolll this that the llrcJthoracic gland of cynthia is influenced

to be activated by the brain hormone of ricini and release the hormone Lo

emerge. Two pupae of J>lIi!osmnitt cynt Ilia, one of which had been kept for a

year in a cold storage to acl i vale I he brai n for hormone release and the other of which pupated newly and had not yL'i iwell activated, were united back to back parabiotically. Both inclivicil1als cI1wrged sitnulianeollsly.

Vlll-0 Parabiotic l'xperilll(,l1t:l on the hormonal 1l1L~challi;lm

in (kterminatioll of ('mbryonk [mel pupal diapuusc

1. "BHIIlII\ \ 111111 II·. UlJikd III'"d III hl',ul pafilhiuli. ;dl\' Il'IlIlI pllllai :,tiH~I' ,11\' n'l'ull1lll1f~' (In,· 'v i! . .;, lli,tPOIII';t· q.:J!

\llilll1l1"l'l :Iud lill' ulhl~r it 1Ii1I1!\iiLpa\l~lt"

t'~~~'!lltldul·l·r. A~i iI 1'1'111111, lilt, latlt" ~lhdll Ill' I'Ilitn~'I'11 ILl by II IliaIJall!,t' ")U! b,iCl II

'" :1 M"lh~, d",i"I'1i 1101111 11(11;111111111 1111!' II

ot 1,1I~II'd.iill'illI:,jIl~: 11~llm HI J'JI/J'J.~.mUII fh',,11 ,Ind ;Ii/II,tlHrlU,.l P\tpa,ol'f~

I, ')'1"",,1. . ..

:~, i Hllmhp.: flHlth. Ifliitl P'IJJ!tI~ unill'lI JI,II',lhllllit'lIl1r hi.tl'h. III hack ill'l'l'IIIHtiatlllJ.{.

Till' l'l'~ildl h tlw !iHIIW lI'i til{, 1.

l"lilulation hi 1I1'I'l'~,~mry 1'111' 'f [II

Jar I'm!; I, hU'1 lUI l'lfl,,'t 011 ':HIJ: diapalL',"

,I. !\II-dill; JWlll paralll"lk 1111111/1 pi ,I ]Jupa kl'JlI ,ll lllw II'mp. 1.lr

tllW Vi'aI' and IlI'Y.'ly 1IL1j1iltl'd pupa

(If P'Ii'osamia ('y'lf"'11 I

S. l-'UK1.1UA

VIII-7 Influence of the unbalance between hormones ~ecretecl by prothracic gland and corpora allata upon the development of the silkglancl.

When a silkworm of the fifth stage was implanted with a prothoracic gland

Sill{worm Genetics Illustrated 101

of the young fifth stage larva, it did not pupate but repeated further larval ecdysis except only a part of the mouth which pupated. 'Such a phenomenon is called prothetely. The fact shows that the larval ecdysis depends not only upon the hormone from the corpora allata but also upon the hormone from the prothoracic gland. It seems that the antennae are the most susceptible organ to the hormonal unbalance.

Sometimes there are cases in which the silkworm cannot spin cocoon due to some unknown cause which cannot be attributed to any known disease. Dissection revealed that the silkglands have some abnormalities. The abnormalities are also induced by a high temperature shock at 32·C. given at a certain period of the third or the fourth instal' which would coinside with the release of hormone for ecdysis. FUKUDA (1956) assumed that an abnormal high temperature condition during the rearing coqrse causes one of the major factors responsible for non-spinning larva' frequently seen at farmer's house.

VIlI-7 Influence of L1nbal~ncc of hormones secreted by prothoracic gland ~Ilc\ corpora al1ata on

the development of the silkglanc1

1. Nurmul 5th intitnr larvn (Idl) prolhetcllt: 6th imslM larvn (riglll) prudu.'cd by transplantAtion

01 1 he prullwnH:!c glands.

1, Non.spinni'ng larvl! among normally spinning unu:]. Nlln'lipinnln~~ appear in dHhm~nt percl'lltanl's In a (lIff~rcnt envirunm~'.nl9.

5. Vnr!ous types of abnormal silkglands from nOIl.spinning lu-r\!;H~ (r\~~ht one h normal), Thf~ ddormations of the glands urc rutl\l.'r 'illglll tlwn those of prothcwlk ones.

S. FUKUDA

VIIJ-8 Gene-controned mechanism of the internal secretions concerned with the growth and development of the silkworm (S. MOROIIOsm).

(A) Traits of the genes controlling two kinds of secretions.

102 T. Yokoyama

A growth-promoting hormone (G) is secreted (1'0111 the corpora allata (CA) and converts the duration of larval slagc, body weigh!, secretion of silk-matter and 11101tinhHll (molt-numbers) into the direction to decrease but voltinism (generation numbers) into the direction to increase.

A growth·inhibitory hormone (II is secreted from the suboesophageal gan· glion I SG) and converts larval c1 Lll'atioll, body weight. silk·matter and moltinislll into the direction to increase !Jut vo,ltinism into the reverse direction.

"Maturing modifying gene" is located at about 1,.0011 lhe Z chromosome and controls the maturity of insects. According to our investigations, this gene is likely to conlrol the function or tbe brain and modifies the activities of the corpora nllata anc1 Huhne::;ophageal ganglion through the nerve cOJ'dmis· sures from the brain. There arC' live 1 YlJeH; l~arly maLuring ILm'), internwcliaLe maLuring {I· I ·"'I"I 1.11(1, 1. 1.>11', 1 r·II/'I} and late maturing (Lm). The dominancy relation is L1JI>·I·I."".;: ... !J."" ·'·I·I·1II'.>Lm'·.

"Major gene controlling molLinisl11" is located ett 8.0 Oil the VI·chromosome and likely to modify the function of the corpora aIIata controlling the growth·

VIII-H Gl'!lc··conl:l·ollerl ltH'chnnhilll (If the ilHC'l'llal spcnllinns COnCl!J'neo

wiLll I he gruwl h ancl (Ilwclo])ntcnt of lIlt' silkworm

(irur rliff('wnlilllhm of ',Irlilm flf IH'IW

l\f:lin g-erlC cnntmllifllf ......_..... nH1ltlnl~im [M'>+i\f»ftl~)

({)CiUkA, '31; SHEMUtlAllIA, 1'17)(~f'IIIOIiCI11I1, lInl',)

JrU(,f"{IClion of j{cmc

t'lJrpU9 ullut um

(N, e. r\'I!IIIlIIIII~all. Ul1t),)

Scx"linlwti mudif)'lng ..... Brain gCI1~s (T,"'>-tf,m>/.m t

)

{Smm. '2fi: N"OATOMO, ':!Ii: ([\111110110')111. MllIlOml!Uu. I,m: TAKAfiAI{I, '!'i(,) \Inn.)

Main Rein'S mnl rollins' vll,ltlnism (r·;-.~. r.-·\")

(nrllwth hOI'lUon~) :} (J!OWUll(ll,. 1~l7: KIM, '3\)

Nl'rV(' l'omml~I:\UI'l' }

~)UI)uN10I'JlnH('nl

C""i<' !llIlaner Ilil(. :11 I Mfl.lII)

(~111l(OIlI~IIlI. 'rim

fil'llk Iml:lnl'(~ lnj{. Ijl Il'/IJ,,)

(~'1IIHUIIlI'iIlI} 'fili)

} (MOROIIO'lHI !:1m! M~!'lAHI. ':'iG) (MlIIWIII~",1I11

Un\I,)

~:anulion Hrllwlh· luhlhitlll'Y IHII'IIHlm~

rFlntllUA, ';,1: IIAllluiAwA, '[i~)

Bruhl hnrTllllrll' ....,. "I'mlllll';Il'il-glallIl ...... illlrllHlIW

(FUKUlIA, "In: MUIHI(.A,

'·111,

o.,,·olopmOnlal 1",lann, (fig. 9)

Lm+Af I (iruwlh fUlwthm

J~m+ V f)t.~v(,dupnwnl:11 IUIU.:tlun

(MonUIlUl:illl, unp.)

1

IJllrmopal antagonistic iJalance (fig. r),6) .. ,

I(;f(/l) (,I\1UllOlltHUII. unp.)

Al'IlVUllon {If llrulhoradc 1:11\11(1 Iwrl1lmH~ !WII,I,IAM!I, '·li: InIlKAwI\

,,(Jlht'r\:i, '[il!

-I- Variou. lypo. of ... Mullini,,", ili~. 7.HJ _ Vollinl"" Ifill. 7.8) molting' cycle lIormo"al 1",lnncc 1(;/(;/) lI'lflTlOIUII balance (iii/G)

GenIc [)Ulnn,·c (M/V/I.m) Genic hulan.c (VIM/I.",)

l~OROIiOSIiI. unp.) (MORilHOiUII. unp.) (MOROIiOtlollh unp.) S. MOROHOSm


promotion (parallel to the function cd~trol1ing molt-numbers). There are three types; trimolting (M3), tetramoltil'llg' (+M) and pentamolting (l11°). The dominancy relation is M3>-I-M>M~.

"Major gene controlling voltinisni" is locatecl at about ±4.0 (perhaps +4.0) on the VI-chromosome and is likely to modify the function of the suboesophageal ganglion functioning to inhibit growth (parallel to the function control~ing generation numbers). There are three types, univoltine (VI), bivoltine (+V) and l11ultivoltine (va). The dominancy relation is VI>+Y> va.

(B) Interactions among three kinds of genes (Figs. 1~4).

Fig. 1. Principle of developmental balance. Left half, loci of the genes, Lm, IvI and V; right half the relationships between

the function of the brain (Br) moclifyl:n'g the activities of the corpora allata (CA) and suboesoplUigeal ganglion (SG) aI1t[:the function of the corresponding genes. The early maturing gene (Lme) sligll:tly accelerates the function of the corpora allala and slightly inhibits the functi~n of the suboesophageal ganglion through the nerve comtnissures. The late ~turing gene (Lm) weakly stimulates the activity of the suboesophageal ganglion' and slightly inhibits the activity of the corpora <Illata through the nerVe COl1'l'1l1isSLll'e. The function of the corpora allata is strongest in the l'vID gene among three genes, .M.", +M, IvIs, and that of the suboesoplutgcal ganglioIl is strongest in the VI gene among three genes, VI, +v, V".

Fig. 2. Diagram illustrating the function of the brain (Br) controlling thc corpora allata (CA) and suboesophageal ganglion (SG).

p, promotion; i, inhibition; ~, ~, t, relative secretory power of hormone; @, @, ~'i), relative quantity of corpus al1atlll11 hormone; ®. @, @, relative quantity of iiuhoe~wj)hageal ganglion hormone; ;=, antagonistic action of two hormones. The functions of CA and SG organs arc different according to moltinism anc! voltinisllI. There arc live types iu the sexlinked maturing gene controlling the htnction of the brain: The early maturing gene (Lme) weakly stimulates the secretioll of CA <lllll weakly inhihi ts the secretion of SG through the nerve commissure:.>, while the late mal Llring gent) (Lm) weakly promotes the secretion of SG and weakly jnhiiJit~ the secretion of CA through the nerve c0111missures. The growl,fl.pl'omoting hormolle G and growt.h inhibitory hormone I act to each other 'aIHagl;nistically .. An antagonistic balance in the earlier stages determines tnoltinislll ;IIHI that in the later, vollinism. Moltinism is genetically controlled by a genic balanc!:! (liJ/V/Lm) and vollinisll1 by a genic balance (V/kI/Lm). These two arc important self.regulating characteristics throughout the life cycle.

Fig. 3. Diagram illustrating a genic balance between the major genes controlling llloitinism and the sex-linked maturing genes .

• ::!. direction in change of mol tillisll1; --, -, , stable, intermediate, unstable relation in chang!,! of moltinism; H. L. high or low incubating temperatures. The early maLUring gene (Lme) diverts the major gene controlling molti· l1ism 'towards a dominant direction, Ma~-+,If<--l'vIG. and the Jate maturing gene (Lm) towards a reverse direction, 1\11"-,,+ ~l_·>lilr.. High incubating temperature (II) COllverts 11l0ltitli~m into a recessive direction, MtJ_.'-I·i'J_.1\I1", and low temperature (L), int(l a dominant direction, 1v1 9<- + M<-1\I15. The modification of inoltinisll1 by ihcubating temperature may be clue to a change of the fun_cti(ln of the young brain.

104 T. Yokoyama

VIII-8 (B) (C) Interactions among three kinch, of gene~ and antagonistic balance btHwecn t wu kind!; of hormones

Fig. 3

--+ II --1-_1.

Fi~, :, A. Organ,

(@) r;(&) 11 r@ @

n. FUI1I'liom

bl. 2nd. :JnJ. ,Ith. [jth.

L:\f .... al (iura lion

Fin· l. Ptindvlc IIr dcv(!loll[Ueolu.t balance

".~ rM10

VIr", 1_ Y I :I.il ~,(J

-----_._----

(./IIf, ,I,m, tnt

'--o.---y--,-~ ~ ~ (il~) ©~ ©! ((dJ\Q).(2(J)(~ ,ell

L---------J AI\I:i1~C1I1I~itil: Alllag(llli::;tlr. hnlaIH7c in IIII! hal;ltlt'(! in lh(~ eurllrr f;tall:t'~; adVi!lIl'(.,d ~;ta"{'s

J J

(M/F/{.>II)

(lellit' haianl'f' IV/MIT.",)

i 1 1v!liltinbm (i/l)

IlpVcl0\ll1lt·tHal 11alann!

T~I1H tlI itrllwl II L ~ [J('I,1('ll11Illwntal t.

FiR. ,I

--11-<:"--- L <E--

Fig. fJ A. l-:.ICh Inslar (!'iliffl' Illlinl~i

,;-F1"'''.;;---..

~~~JI;'l~1 ,~ ~I Rl r::1 =-: __ J

III III 111 III :1

II, AI\ \",'.,,1 stages

VrgrtatAv{' IIhiHi(' ncpro1\ucliv(' pha!ie

Mollillimn 'C

VOl lin I".

S. MCmOHOSlU

Fig. 4. Diagram illustrating a ,L,,'cnic balance between the major geneH controlling vlllLiniHl11 and the Hex·linked mnl.urillg g()llCH.

<=, direction in change of voll:inislll; -_, __ , ,HWble, intermediate, um .. t'able relation::; in dl<lngu of voitinislllj H. L. high or low incuiJating tempcraturcs. The early maturing gene eLm") divertH t.he majo!." genes controlling voltinhnn [:owarc1H a recessivl.' direction, V'J,,", + J' -<- VI, and the late maturing gene (Lm) towards a dominanL direction, V"-> II' -> VI. High inwbaling temper· ature (H) 'converts voltinism iilto a dominant direction, Vll_)o -I V --> VI, anel low


temperature (L), into a recessive ditection, V»<-+ V <- VI. The modification of voltillism as well as that of moltinisl11 by incubating temperature may be due to a change of lEg'r{lllction of the young brain.

(C) Antagonistic balance between two kinds of hormones.

Fig.' ·S:' A. Diagnlm illustrating relative functions between corpora allata and sub,,' oesophageal ganglion.

The balance between the function of corpora allata and suboesophageal ganglion is affected by age; in the very earlier insLars the function of corpora allata which secrete a growth-promoting hormone is little affected by the ft~nction of suboesophageal ganglion which secretes a growth-inhibitory hormone, while in the later illstars the fUllction of corpora allata may be largely affected by that of su]JoesoplHlgeal ganglion. Thus a critical point in the larval stage exists in the third imltar, as seen in Fig. 5 B.

Moltinis11l as well"as voltinism are too complicated to explain by only a genic balance as above mentioned_ ThuH an antagonistic balance theory in relation to mollillh;nl and v(Jltinism wa~ proposed by the writer.

B. Diagram i1luOltrating a relutive function of two antagonistic hormones (G and I) in the larvul lifc.

(C), the critical point at the third instar; 1. 2, 4, 5, each- instar. The larval tllll'aLion of each instar is determined by the physiological balance of two hormones and the wdght of lmv'll boclieH. The greater the difference of the functions of the two hormones and tlw increase in weight of larval bodies are, the longer becomes tIll! larval duration of each insta!"_ Thlls the larval duration of each instar in tlw silkworm is shorter in the followiug order, as a rule; 2nd, 1st, :lrd, 1t11 and 5th instaL

Fig. G. A. Diagral1l illustrating the effect of age Oil the relative functions of the G and I hormones ill each insta!".

1,2,3, 11,5, each in;;lar; Jl1, molting; p, pupation; white areas, growth·promoting function; dotted areas, growth-inhibitory function. The rise and fall of the two fUl1CtiollS in e:lch instal" is rl!sembling that of the entire larval life, though there are some variatiolls. In the earlier stage of each iUHtar the growth-promoting function is Huperior to the growLh-inhibitory function and in the later stage the reverHe is the case. J\ cri tical stage of each instar exists in which the two fUllC·

tions arc uljldvalenl. 13._ ])iagram illlistraLillg the relative strength of growth-promoting and

-inhibitory futlctiom, during the entire larval life. A, vegetative phase (lst-3rd in;;tar8); 13, rCllJ'otluctive phase (4th 5th il1star;;); C, the critical stage in which the two functions arc L>aluncetl; wliile area, growth-promoting function; dotted area, growth-inhihit\Jry funcli\ll1. The earlier instal'S are the vegetative phase in which the growth-promol.i ng function is superior to the growth-inhibitory functlOn and till! latur instur;; arc the reproductive phase ill whi ch the growthinhibitory function is superior lo lhe growth-promoting functiou_

Moltinism and voltinisl11 are two important self-regulating characters in the life cycle of the silkworm. The former is determined in the earlier developmental stages and mainly controls the molt-numbers. The latter is determined in the later stages and mainly controls the generation-numbers.

106 T. Yokoyama

Although both moltinisIll and voltinism are determined by the' .tii~4Il.nce of the two antagonistic hormones secreted from corpora aUata and suboesopha~~Fll ganglion, moltinisI1l may be c1elenninecl predominantly by the quantity of l1he. growth· promoting hormone secreted from the corpora allata, and voltinism may be determined predominantly by the quantity or the growth.inhibit~ry hormone secreted ftom the suhoesophageal ganglion. The brain controls the secretive activities of these two hormones through t1W nerve commisSL1res.

VIII-9 There is the recessive trimolting, rl, besides ordinary dominant trimolting.

The former is on VII chrolllosome, D,96 distant from q. The duration of feeding period of rl is different that of ordinary lrimolting 1\1\ the former develops at the same rate as the telral1lollings, eliminat.ing the last stage (VIII-iO).

VIII-I0 Comparis()n of lilll'al ion:-{ C'xpn'sl!ci by Hcvural g(~n('s

cont:l~l'niJJg t.lw moll ill!,'; cJutnll'lcl' in Hombyx mori

day 1 2 3 4 5 G 7 R H 10 11121314 Hi 16 111.819 20 21222~ 24 25 rocoon weight

tetra·moult. .M·I I I 1=-,= [ o recessive tl'i'n~ult. [ I I I I other J'Qce!lsi\,i? I I I 1 :I lri·moull. I'i.~

ol"dlll~ry t!'l·moult. Lr iIf' . I I 'I

11l·m·.Jult. 11-// L._~I ___ .. I ____ J lIt I

hatch lIloUlt. in!-ilar ripe

The worms homozygous ill 1'1 lWCOlllC tdralllll11ings or trilllolLings c1el.51m.d· ing on the nature (If environmental conditions. Mol't~over, il is possible to seled different strains of trinlOlLings or lelramoltings.

If the F J hybrids bctwcl~n the two strains mentioned above are incubated and reared in a lower or tI higher t.empcrntul'(:!, lhe longer the period of a higher temperature, the less trimolting::l appear \Vm-Dal.

There are many devc[opmentally and genetically interestinp; behaviors of rt when ;it is cOlllbined with dominant tritl1011ings, lIl:J or usual tCiramoltings M·l (lX, VHI-~)b).

Sil k worm Genetics Illustrated

VIII-ga Change in manifestation of rt in the crosses of two stnlins, A and B, inc,lbatioll and rearing temperature

black ~lnd while lines show reciprocal crosses between both strains

rtfl "'rl

pCTt:cnl.'!lf.' 01 rCCCS!;iVl' I ri,mo/ting

~o " ....... _ .. ___ ~ .. ___ ... ____ ~. _____ Jo

'· .. ·28 ::3

28 E =s "1': I'~'

..• 2" ...• 23 ~~E~~~~~~~::, ", 2H ~ '\. :!~ .... ~ ~:':3 C... ~~ sHain A and 13 do nol l;h.mge

'. ~I'l ~~'J their rWlUfC hl nny londilion

VIII-Db Changes In 11101tiniSI11 by the combined action of two genes, I't and M3

phenotype

gene combination

1'1 hal> a llaLure ttl cuL oJT the last instal'. III the case of NIHrt, how·

ever, 1l10St. of larvae do llot bl~COIl1I.! bil1lo1t but become lila. In the CElse of M I rt almost all larvae becol11e so·called "recessive trimol t ", but sOllwt.imes othel' twu type>; uC larvae appear as follows: 1, normal tetra· mol t as same as in the case uf 1I1"l't, 2, uther type of trimoulting which is similar lo M:I but recessive onc. T. EmoBE

107

108 T. Yokoyama

IX. Biochemical Genetics

The early stage of biochemical genetics oJ silkworm is marked by a brilliant work of MATSUMURA. (HJ34) Oil the amylase activities. A remarkable work which followed was· a study of KIl,I<AWA (1~37) on the tryptophan

metabolism. There have been numerous stud ies made on the chemistry of cocoon ·coloring mat tel' and the pig men t in the integ umcnt. .l nteresLing results are eXrJectecl in near future concerning the relation between a certain pig· ment and the viability or disease resistance of the silkworm.

1. Amylase activity in the digestive juice and in the body fluid.

As ~ar1y as U134, MATiWMURA investigated the gClletical behavior of the amylase· activities in the digestive juice and in the body fluid of the silkworm and succeeded in Jincling out ~ genes, the linkage relation between them, distribution of Llw genes among various varieties of silkworm and the relation hetween the HlHylase activities and the vitality.

:2. Tryptophall mctabol iBI11. In the cm;e of silkworm, there are many lllutants which are different in

the color of eyes ane! in that of eggs, normally, LIte blad("(~yed moth laying

black eggs, while the wbitt··(!yecl one laying while eggs. The black coloring malLer is synllH:tizcc1 in t ht' body of sillnv()l'm through seventl steps from

tryptophan in the presence of genes, each corresponding tll a differenl step (Kn;.KAwA ID:17, etc.). Tlw main route is shown. as:

Tryptophan·-) kYllurenine ~.) :·HlycJroxykYllUrenine -) Pigment

In a lllutant WI' kYllurenine is syntlwli:wd hut not 3-hydroxykynurcnine sillce the 'lllutant has IlO cm:ynw concerning that: chemical reactioil. III another

lllutant l(l,!, :·)·hydroxykYl1urenilW is made hut not the pigment. 1t waH [oune! recently by INA(;AMI (HlGfi) t hat in a mutallt r/l, there is no ellzymeH which are concerned in the chemical processes to COllvert kynurenine into <lnlhra· ny Igl yci no and :1· hydroxy kynurcnine into :~. hycll'OxY'Lln thrany lic acid, sLlch cll;r.ymes exist in normal strains.

3. Melanin. Melanin is a blackbh pignicnt commonly fUlind in the integument of

silkworm. There are several gei1cs related to the melanin formation. The interaction among ane! bdwedll them and the genes of transparency of the skin was sLudied by lhuw\ (19,1;1) and hiB collcagues. The cllvironmental condition which affects the melanin formation was studied by HAIm:uKA (19112) In a mutant black pupa, /1)1.

11. Pterin, riboflavin and uric add. In the integument of a mutant silkworm lemon, [em, there is a pigment

pLerin, water soluble and beautifully fluorescent. Xanlhopterin·B, leucopterin


and Ieucopterin-B are proved to exist in the skin (KIKKAWA 1950, ARUGA 1951, et al.). Several investigators Suppose that pterin is derived from riboflavin, a great amount of the latter substa·nce is found i)1 the Malpighian tube of the silkworm (KOYANAGI 1938) and the amount of which is closely related to the translucency of the integument (KIKI(AWA 1944). The translncent integu, ment of the silkworm is brought about by the lack or weakness in the accumulation of uric acid in the epithelial cells of the skin, which is controlled by several genes (luccr 1932, SHIMIZU 19'13); The uric .acid formation is closely related to ri boflavin (HATAMURA 19119) .

. In a certain instance the presence of pterin is related to the hardening of the cuticle of the skin (TSLJJITA 1955) or to the virus susceptibility (ARl:JGA

1955). lX-l Tryptophan metabolism in Bomby.'!: mori.

The work in this field was started by KIKKAWA in 1941 in connection with the problem of eye· or egg·coror formation, and then extended by

BU:I'ENANTlT, .lNAGAMl, etc. The figure shows the pathways of tryptophan metabolism in Bombyx mari, especially during pupal and egg stage, The conclusion has been obtained fr0111 biochemical studies using several mutants such as white-l and white-2 elc. concerning tryptophan metabolism.

IX-l Tryptophan metabolism in Bombyx mori

Cll,-yH-COOH ~I I GlI.-~H-COOH If Nil, -Vn.!J Oil J II Indole lactic acid

l"rynlophon 011

ACO.~II'-~H:cOOII ro Kyull,ln

~NIICIIO I. 011 I'o,mylkynureulno or I Ai

t / _/ 9-COOH

Oeo.cll -ell-CDOII ~ :-.. N • Nil, """ Kynurenic acl~ X

Nil, "~~ OCOOII I(ynurcn!nc rcd blood ~ I Nil, """"'0

1 CO-NII-CH,-COOn

..J...,wlu/o"l

O~t Anlhronllk all ~ Nil

CO.CII,-CII-COOIl "':Idm ' Nil V I ~ Anlhrnnllylgiycinc

Nil, '_____ , Oil ~ 6rr' N 4, S.Olhydro"y·qulnolin'

3.HY+~~/~~.~:rC.lne '\ .,~ Q~ S:OOH ,·cd blood I' ~ ,,,JCOOlI

Yll-NII. r COOII 0' N "..-/ y <;.g. 110 I Xonlhurcnlc "'~

N" "N fIt~O!~_~1 cool~~1 -NII-CIl.-COOa :-... 0 ~N~ :-.. I, ~ NIl,

o Nlcoll"I.. 0 I 0 I XnnthommOlln Id HI~droxy". 3.H)'droxy.nlhronllyl.

(pigment) ac ~~:/"nillc- glyd~e --_Actu.l pathwQY H. K'KKAWA

----Unlikely Jl.lhwny A, llUT~N"NDT ~ PW1~·~t\~:;~nl.d 1(, INAGA"'!

110 T. Yokoyama

IX-2 Mutant .eggs concern Lng' tryptophan metabolism. 1. White-l (tot). In this mutant, tryptophan is converted into kynurenine

but kynurenine is 110 furlher converted into 3-hydroxykynurenine. Therefore, kynurenine is accumulated in this mutant, and h1 a later stage of pupae or just before hatching, kynurenine is converted into various substances, such as kynurenic add and qL1lhranilic acid etc. as shown in the figure.

2. White-2 (tV~). In this mutanl, lryptophan is converted into 3-hydroxykynurenine through kynurenine, bul 3-hyclroxykynurenine is not converted into pigments. 'l'11ere1ore, the accllmulated a·hyciroxykynurenine is converted into xanthurenic add and 3-hycll'oxyanthranilic acid etc., in a certain stage ot pu[>ae and C!!'ms. Bul, ni.colinic add does not se'em to be produced from a·hydroxyanthntnilic acid in Homby •• ,

;1. Reel (I'l'i. /\. mULant of fuscanil1c pigment:;, KnG<AWA et af. (1954) hllve shown thal the mutant lacks a purplish pigment in the compound eyes o{ llloth and in Lhe serosa of eggs .

• i. Normal ( f' I. Scvl~ral kind:; or fuscctninc pigments are assllmed to exist.

5. Arti ([cially pigment.ed eggs produced hy the injection of a-hydroxykynurenine int.o tile pUJla of /I't l11utant. The compound eyes of the 1110ther moth are also piglllented. These facts indicale thal the metabolic palhways after :1-hydroxykYlluJ'l·llinc. formal ion arl~ llormal in this mutant (11. KIKKAWA).

lX-!! MuLant l'gg~ ctlllt:cl'lIing tryptophan lllclaboJi~1ll

No.1 white 1 ("'I) No. ~ white 2 (u'J)

~o-·,·· ,'. ~tr ,"

n

Nil. ·t nurm;\1 (+) NII.:i Artifkiilily Jlj~nwJlIr.d cgll'! I1Tfldurcd h\' the 111-kl'( lUll (If 3·lwtlruxykynurt'niili' in II) lhl' IHlllil IIr 11'-1 IIl'ulant

IX--3, IX-I!, IX.-G Tlwse three exhibiliolls show II,Ie studies hy INAGAMI

(19Gfi) Oil the tryptophan metaholism in the silkworm. The body-fluid in normal strain changes its color into black when exposed

to air, while in a mutant strain l'b into red in stead of black. The difference


in constituents of blood between normal and rb is that in the latter there is enormous accumulation of 3·hydroxylcynurenine which is concluded by the author to be converted into 3·hydroxy·anthranilic acid, which is again changed into 3 yet unidentifIed substances F, I and L. (IX-1 X, Y, IX-3 (2), IX-5 (1)).

The red pigment which is a characteristic feature of rb is formed by the oxidation of 3·hydroxykynurenine, while the 11orma1 black pigment is formed by the oxidation of tyrosine like sUbstance. If the both substances are in different proportions the color fluctuates bet.ween red and black, for instance, in vitro experiment, the mixture of 2 mol dopa, 1 mol 3.hydroxy.

kynurenine and t.yrosinase changes into blackish hrown, while the mixture of 0.5 mol dopa, 1 mol 3·hydroxyl<Ylll.lrenitie and tyrosinase changes into ,red. The blood of F~ individuals of the cross -I- X rb shtlws various shades of color when exposed to alr (fX-4). The author added another example to the

IX-·3 Manifestatioll of red blood (rb), concerni;lg tryptophan met'lboJism

exposed in the air 1. Normal body fluid --------, black-brown

rb hody fluid --.--".---_> red

2. Formation of the red pigment 1) Abnormal accumulation of 3·hydroxykynurenine

3·hydroxykynul'onine content ill the body fluid of some lllutants nt .~I·h instar measured by diazo·oxide method

normal -I- 4O/lff/ml

white till

white U'2 52

reel·blood rb 782

2) Formation of the red pigmellt iI~ llitro Normal body lluid -.--------) black-brown Normal body Jiu i<1 -I- 3·hyclroxykYl1urenine -> red 1:l.~~_WI1

dihyclroxy. phenylalaninc

-I-

2 mol

1 II 'I

0.5 "

O. 25 "

3-hydr oxykynureninc

1 mol

1. "

1 "

" -I-

ty rosinase (potato)

+

+

+-

+

+

+

color precipitation

black

black·brown -H-

red·brown + red ±

red

yellow

11~ T. Yokoyama

one genc--onc enzyme theory by showing that there is no enzyme in rb which converts 3-hydroxykynmenine into anthranilic acid (IX-I, IX-5 (2)).

spot

!\

Il

C [)

E

II

G

II

I

.r K L

IX-4 Variolls shades of blood color of rb when exposed to air

F, of (,1':' rb) 'pot" of body nuld

,II luf'.·a, ,b O~l{

tlO 1"I1ia I normnl rll type lrpO lJod~' hnrir body n\l i~1 nlll~ nliid

I, 3·hrdr"I·· kynurenine

dlhy~I'",Y-

~I~"~;;~~ + 2mol 1 mol -

3.h)'<lro"r· _ L 101 2 mol + krnur-unlnc n Lyrol!linosc ,j' + ...

a·hrLil'oxykynu 1'I!IIInl)

ubtnincd from tit!.: (MdV Iluill of ,b

K JNAGAMt

IX-fi (1) Tryptophan metabolism of [family:>.: mori

l'aJll'1' chromatogram of tryptophan meLUholit it'" in urine of sonw lllutants. Solvl'llt, butanlll: acetin' add: walt~r ,~:l:fi

I norma IH lluort'scelll'l,! i

! 1

glul:ul'Onide of :l-CHI·kynlL. II. IIH ! yellow grt'I~1l i :!: sulphate of :HH!·kynu.

! II. Hi

I

~!~

:l·hydra xykynllrt'ni IH' II. :lH

I

1

kYllul'L!llillu II. ,1~ hllw grelm I 1

xnnllllll'Cnic adll 0. ,IH yL'llow grl!en i

F 0. [i[i yellow iJlue I II an t 11 ra ni lylglycilll' O. iH Jlurple II /1.H·dihydrllxyq llinolinc 0. HO yellow

O.H2 pale blue II a·hydroxyanthranilk add 0.88 blue pllrJlll! 1

untltrani lie acid 10. \)2 jlul'ple :J:

L I O. [is pale blue

kynurtininr -t : UJ1t_hrnniliC add -I' tv 3·hydroxy. 3·hydroxy. kynurenine rb anthranilic acid

kynureninase

1

1

·111

II -1+1·

± ± -I

+ -I

II·

m ·11--I

·1+ -I-

-I ±


IX-5 (2) One gene (l'b) to one enzyme (kynureninase)

>.

'j 0.3 ~ ~~rma I 'C

'§ 0.2 D.kynuren!ne .- 0.1 ~ without D, L-kynurenine

1 30 60 90

~ time In minutes

EnzYIl1<:1tic degradation of kynurenine

51111. of 0.002 M n, L·kynurcninc, 5 mi. of 0.1 M phosphate buffer. pH H.l, 211101. of Cl1%YlllC SOhlLioD, H20 to 15 mI.,

temperaLure 37·C .• wave·length 360 mfl K. IN.A,GAll'll

113

IX-6 Histochemical ob~ervatjon on tyrosinase concerning melanin formation of s-l11oltlec1 IS. KAWASU).

In an aUempt to demoJ)strate the mechanism of the melanin formation in 1 he silkworm larva, hislochemical studies were carried out on tyrosinase of black and while parts o( the integument of a mutanl "mottled Striped".

Tn general, the melanin pigmenL 1n t.he integumenl of the silkworm larva deposits in ex()culicle, buL not in endocuticle nor in epidermis. And tht melanin pigment is renewed in each molt, that is, at the molting period the old cut icle i~ casi 0[[ and new cuticle coni alning melanin pigment is produced by the epiderm i~. IL ha~ been reported that the tyrosinase &cti vHy in the integ-ument of :iOI1W larval marking' mutanls measured by manometric method is hi~hcr than thal of a normal lype, and the difference dudng the molting period i~ clue In that of ti1C tyrosinase activily in the epidermis with new cuticle. However, m icroanalYBis 0 f the enzyme distribution in the integ-ument

1 X~()a II1~t()c1wll1ical observation on Lyrosinase concerning melanin [ormation of s·11lottlcc1

Integument C)C

S·moltlcd

Q Schematic figurr of Integument '''lih whit(: 'Iml blnck purts of S·onoltlcd

Cross section of integument showing changes from 4th to 6th Instar

114 T. Yokoyama

can not he done unless histochemical method is used. For this purpose, it is convenient to use X-ray mutant" mottled Striped ", because in this mutant there are while patches among the black melanin part and, therefore, both wh ite and black parts can be investigated in Ol1e preparation (IX-6, a, b, c). Tyrosinase can be demonstrated histochemically by observing the formation of brown and dark c1epm~its produced in the tissl1e sections which have been incubated in substraLe solutions. For the present investigation, freezingdrying' method was adopted, and as substrates, tyrosine, catechol and dopa were used.

Tyrosimlsc occurs in the exoculiclc, cndocut.iclc and epidermis as we}! as in the muscle and adipose tissue (lX-O, h, c). In a [ceding stage, there is no diffel'cllce on the tyrosinase action ilcLween white and black parts. At the early stage of tlw molting period, the C'pickrnml cell--upper part or all part of the cell--of t.he pigmented part was stained in slightly darker color than

Tx~m) Fn!e%ing drying section of integument

incuhatcrl wilh calechol Ht early Htngn of 4th moulting ('<~()O)

IX-(k inl'lI1Jntl~d with ('al('l'I101 at: middle Hlage of 11th Ill()ulting ( :lfiOO)

innthatccl with clopa at middle stage of 4th moulting (>:1500)

ext' ... ('x(l(,lItkll~

em: ... (~nd[)cl\lklt~

nc ...... lWW cuticll~

l· ...... (~]Ji<ll~rl11iH

ty ...... lyt'oHinase IllllH ... IllU"c!c

h, h' ... bot'(ll~l' of 1Jluck and whitc jlurtl-l in old and new culklcH

S. KAWASE


that of the normal one. 1\t the middle stage of the moli when new cuticle was produced by the epidermis, the tyrosinase action of the new cLlticle in which melanin pigments would be produced lh~reafter was stronger than that of non·pigmented part (lX·"G, b). However, in the other part especially

in the basement part of the epidC'nnis, the difference of tyrosinase action between the both parts could llot be observed. 1,'rol1l these results, it can be said that the melanin formation of the silkworm larva is closely related to the tyrosinase activity in the integull1ent.

JX-7 Influences of the dominant chocolale gene (I-a) Oll the manifestation of some larval markings, egg color and skin color (S. SASAKI).

The dominant chocolate gene (f- (I) is located on the IX chromosome, which always inhibits the formation of melanin in the larval exocutic1e controlled by the genes belonging to p·multiple Ellleles, such as norm"l rmrk.

IX-7a [-Cl inhibit" tnc'lanin formalion in a few larval marki I1gs

I hI/I, I-a/p,' I-a/I, PIp"

IX-71l [-If dol'S 1101 inhibil melanin formiltiol1 IIf b'hr:! (,7,{?) and Ursa (U)

"

116 T, Yokuyama

jng ()-1'), Striped (PI, Black 1/1'\ J\l[oricaud 1/1"'",,1r\ In the Jigun~s of lX--7a, the inhibition of ir~ and J)" by r (l j,; illustrated.

The I-a gene dnes not inhibit t11Q blackish brown or yellowish brown pigments produced by sLlch ac1ditionalmarking gem's m; Zebra (Zo), Multilunar (L), Ursa (VI. When I-a is combined with om' of these marking genes, the lal'vl:ll marldng becomes (lilllte in color. This is clu(' to the facl that I-a inhibitH the melanin fOl'lllation by t1w ilIad: color g(:I1(, of the newly hatched larva (·I· e/,) and tile fUJ1danlC'l1tal markil1g ~~cnc I 1 1'1. In the pll, Ze, I-a or pll, [1, ra individual, melnnin produced by }l'1 is inhihited, while black pigmenl formed by Z(' OJ' U remains uninfluelll'c'cl (IX 'ib\'

In mating a hlack l\I.Ui; Clnd it white L ('l~i-Y, the infllH'I1l'C' tlf the black egg on the white onc l'lIntimws to cxbt in till' ('0101' or the nt'wly hatched larva, and it is m-lLlul that, when ils lllot\l('l' ha~ I /n'l l'01H;titutiol1 till' young larva with wt/w{ looks like a hl~l('k (ll1l'. 011 tl1l.' olill'1' hand, the colors of the dominant chocolate YOLlng larva just aftt,!, Iwkhill,l; in tlte (TOSS of I-a/I-a ;<-Il't/U'j F,~ or in ll10 back l'ro~;s (If F I '!lI'I/,I'1 al'l~ of tW() ldncls of shades, 1. e., dark and pale. The' ronnel' 1)('['0111(''; n 1)la('k"(~ye(l mot h and the latter a white eyed. I\l10tl1('1' nol ict'alill' f,wi. is that the ('m~ color uf hybrid F! (UII/W! ',1 >~ r ((IT ([ \)) is alnlOst l'olll1'iloss a!HI t lIt, Cll1'nl11ll,l.(l'll 1'('111<1in8 as kynure·

nine ill the egg (lX-i l', (\1.

IX-Ie r-:m~~; qf' 1"1 IIYllI'jd (/I',', /-rr.',·1 ar<' allll"~;1 l'I,f"rl,,~·;s

1111,] I'! 11'11 11 1 "-";< '11 l','m;lill!; :1:; !;"1111I"'llilll' ill l') ';.1 ';

If'l 1/'1

vVhcn l11dallill is (lII'111l'd fly ~aH'1J !.;('IIl'~;;r,; i ", Jr", e', /,1t, I "ZI', 1"rT etc, in the larval eX(lcuLit:ic , X<l11111lIpt('1'in-l\ P1'Ot!IIi,(,(j I,y !('/Il ,!';C'lll' h SC<ll'cl'Iy recog· nized in the hYLJoderlll]s (Ii' th" l'l',l('i (Jil , 11<1\\,('\'('1', Wij('ll I If ,U;('Il(, inhibits the formation of mL'lanin in tIl(> l'Xl)l'ul il'il' 01 tIll' 1'I',!(i<lIl, x<l111 hll[JIl'ril1·B comes to exist (IX-7 el),

IX-7d, lOri. In thl~ l~X()l'l1t kll' of t 11(' larva wit 11 1I1\~ !';l'lll'l icalcll]1st itution, +I-rt/_I_I-"', jJ"/ I 1', II/mil, Illere ('xisl it ('()w:iricra/JII: IlIIlJJ/)('I' uf I)iack pigment granules (Pg), while in the lIypodcl'mi,; ur Llll.: l'i',l.dUIl 11ll' hlack pigment granules are scarcely recognixed, as S('L'n in Fig-. ] 02, ill'cause in t his individual the development of ,I black ", j)ll, is not inhibi1l.'d <Inc! black pigments


to form the pattern are accumulated in exocllticle as if at the cost of the

hypodermis pigments. In the picture the bJack granules are seen in the hypodermis which are not of ll1elanin in nature.

IX-7c1, 102-1. In the exocuticle of the silkworm with the genetical constitution of I-al+, pnj-p, +/lem black pigment granules (pg) in the larval exocutic1e are few. In <ll111ost all cells of the hypodermis the brown granules

such as bpp: are observed, but their number differs according to each. cell. It is concluded that these granules are not of xanthopterin-B in nature but

of tryptophan derivative. IX-7c1, 100-], There exist a considerable number of the black pigment

granules (j)/;') in the larval exocL1ticle. A small number of the granules of xanthoplerin-B are scattered in the hypodermis.

IX-7cl, 103-1. At the basement of the nodules (nod) few black pigment granules (pg) are found. In the hypodermis there exist a considerable nutnber of transparent and small granules which do not' exist in the case of Fig. 102-1. These are considered to be xanthopterln-B granules. When the production of the black pigment In the exocuticle is inhibited by the func

tion of I-a gene, many granules of xClnthopterin-B come to be found in the

region.

IX-7c1 Interaction of pn and I-a genes on the formation of xanthopterin-B

(0 ~

·f· 1-"/+T-tl,PIl/I·P, +Item

+1-" /1-1-", pH !-I_ P, lemlfem

nod. nodules cxo. exocuticlc encl. endocuticle hypo hypodermis

1-"/1_, pH / -I'P, +Iiem

l-a/+,pD /-I-P,lem/lem

x-g. granules of xanthopterln-B ·bpg. brown pigment granules pg. black melanin pigment

S. SASAKI

118

IX-8 Relation betW('(~n t he eli! ute h lack (lid) and several markings, The elil ute black elmt rolled by a rC('l'ssi vc gene fnl iH characterized by

dilute black color 0:1 th(~ dorsal ::;idc of larva, with darker color on the thorax: and caudal portions, '['his characteristic is manifested in homo7.ygous incHvidual of bll, but uncleI' lIClc"ozyg(lLlS c()ndition IJr/1llodil1es the mallifestatiol)S of such markings as 111)rnuti I f P), Sll'ipccl (Jh, Zebra (;(0), Multilullar (L),

Unm \U), etc" by darlwning' the culor of these l11arking~. For in~tal1ee)

brownish lllultilunar 111arking' is ctlnlm;l perfectly changed into blackish Olle in bd/bd, L/L inclivicltlal, hut is partially changed in In/II, D/L one.

I X-H [xC' lal iOll 1)[.'1w('('11 t hl' tlilu( l' hlack (hd)

and SI'VI,I':Jl lIIarld ngf\

I" 7,' T, 11

lJl'liu llutmnl Slrilwc\ MlIl'i,·lIl1d 1"hl".1 Multi" Ut'\~I'

IUIIIII llUlll'rn

I' }I,l ).jl',d /" /Iii 1/ "d ~,;' lId I. I,d UM

II. (\1/111,>\ ,I\( N, YII!iIllTAI\'I~

(',\':·:')'a Transpi'atllafll)n Ill' HIl' (arV;[( lllf('gUl1ll'llf I)':' i'{\(;\SllIMAI,

The tral1sJllantillh)[I~; flf l<li'val in(\'!(lllli('\11s wnl' ('arri('d out lly using sl'vl'ral [arvid markings, it.'llIlln y,'IIIIW and utl-t r<lldul'(,llt ill thvir :lrc1 larval inslal's, ant! p!tYSill,LKI'IWI it'al oh~;l'rv,t! il)ll~; Wl'I'l' lIIil(]i- (In tltt, transplanted parts

wlwl1 tIll' host elltl'rl'c[ till' Itll hrv;il in::tar. In I'a~;(' tltt, intl'.l\·ul1wI11fl of

stripl'd (Ir') , ,'_"·lllUUIL'd Is'''') and IIILtltilllll,tr ({,I with-II I'llI'm llll'lanin in their cuticles Wl're t I'ansplalltl'd til t !Jt~ plain 1 III OJ' 1Ii1l'l1Iitl I I "I, 11ll'lanin pigments were not ohservl'tJ ill III(' donor's l'utiek::. llrk al'iet ill tlw h~lpllcll'rmis of the j>" in natural POSilion (nut Ireal('(\1 was vcry liltll! in IllwnLit.y and the hypodermis was nll( t:lailH'rl wi lit lll'lItral 1'('d, Illil ill tlti' (';\S\' Ill' (he tran.splanted piecl! uric acid in 1111' jr" h~'l)1)dl'rlllb illl'l'i'ilS(,(\ Illuch and stain~d with neutral reel. In this \:aSl', Wl' l'ollle! j'('('().f!:lIize t!tat Ihl' !.(nllllll('~ of uric

acid were transl11i (teet frol1l t Ill' host's Ii ~'IlIl(knlli~, I () tIle' clOllor's OllC,

However, in the Citse when~ lemo!] y(~II()w 111'111) w11 ich cont ains xanthop.· teril1-B in the hYPOdt~n11b was transplanted to tilt' normal, xanthoplerin·B was not affected by the transplantation, i\nd when oil-translucent (od) in

Silkworm Genetics IIILlstratcd 119

which uric acid is very little in quantity in the hypodermis and the integument is transparent, was used as clonal', the hypodermis of clonor became a little whitish or transparent.

When the transplanted individuals had grown to the 5th instar, melanin which is due to pH gene was formed in the majority of the transplanted pieces, but no apparent differences between the 4th and 5th ins tars.

From these experiments of integument transplantation we can consider that the functions of b?th gene and cytoplasm have important effects on the manifestation of characters:

hUBt:

dunor:

hOBl: donor:

IX-9a '[nlllsplantation of the larval intogument

lem lem +1' !emK [emK {emK

-( 1J

lamK lem lem +P tP J( ~ p [( ps K

Smt SlItt]i:

Smt Smtlem + P I-a I-a pSl{

I-Ct p' [( SlIttf( S'JLtleml{ Sl/I1lemJ( Smtj(

t P

psl{ P

LI{

pi ch P +1Jl{ odK

dark is stained with neutral red

IX-Db (upper) Transplantation of knobbed (k) (E. NAGASHIMA).

When the protuberance which is formed clue to the gene function of Knobbed (1\) ill the !JIll segment was t ransplunted to the normal (+k), the clonor's integument was not lJuric.c1 into the codol1l of the hosi owing to the protuberance. So, a Humber of pieces fr0111 the 5th segment with Knobs were used as donors in all these experiments of the integument transplan

tation. IX-9b (lower) Transplantation of striped (P') and S·mottled (smt) (E. NAGA

SHIMA).

The larval integuments of the normal ( !-P) or S-motiled (smt) were transplanted to striped (PS) and S'!11ottled (S"'t), and the melanin formation in the

host portion neighboring the donor was observed.

120 T. Y olwyamu

IX-9b Transplantation of the larval integulllent 1.ran::ijJlanLaUu!l u[ knobbed (in

hosL : jl dUllor: II' Ii: host :··I·l'J( ciOllOl' :·IPK

transplul1tation of striped (P') and S molt led (~mt)

host: I'" d~)lIt)r: I JI K

I~. NAGASHIMA

Tbe format ion oj' ml'lanin whkh is (lLw t() thv gl'J.W function of P' is wry lit tk or nOI1(', and ill cast' tltl' , .... ·n" is llsed. ,tS the liost and donor the lllottlings arc scarcely l\~co.l!:llizl'(1. IVlmcovur, (he hypoderlllis hl~Cl)meS white anel rail hc stained wilh 1H.'utrul n'd.

Thl~se pitcllullll'IlCl were difTl~J'L~llt frOIll t.he ca:,;l' uf /i" integullwni whkh was transplanted to (hl~ /),1 individual and SI) It is consic1ered that these differences occurred hy the dfl'L'is or the donor ii/I I .

lX·Dc Transplantatiun of !-il)oLy (Sri) IE. N!$i!\SJIIM.·$.

In order tu kllUW Lhe l1l('(~halli:;111 of Llw melanin formation in thE! pupal integument ill case or (ran~Jllanlati()ll, Buoty (so I which forms black melanin in its pupal cuticle was used.

When the normal larval ill [l'g'1I1l1en!. with J\nobH ( I l'K) waH transplanted to ~uu1.y in the ·1th-fit 11 i11sta1's, the color [one of dOIlur'H cuticle in the pupal stage was brown, showing no cUrfen'ncc from 1.11(.\ normal one.

On the contrary, in case the sooty was tranSplanted to the normal, the donor's cuticle showed brown color and not black, and the melanin which is due to the gene function of sooty was not recognized.


IX-9c Tran!;plantatiol1 of sooty (so)

host: so donor: + P J( host: + P donor: $0

L'llrly stage middle !stage

last stage formation of epidermis

122 T. YtI!wyaIlltl

IX \Ie[ Sl'cliol1 of I he lransplanted portion (E. N_~GJ\SllIMA).

The sUl;LiullS or the l'()llllcl'lin.l~ part beLween the host and the donor in the integument transplantation were observcd under microscope.

In t11e early sLag", the syndtiulll which was (ormed from blood corpuscles COll1Wt·ted both tissLles, and th:.' S,'cl)[Hlary layers from both sides extended t hemsd ves ancl lmike\. Tlwl1, ~ Of ;\ Iluclt-i or the ~;Yl1citium merged with each other and (Drtlled I he mlc[ci (If the !lew hypodermal cells, These cells lied in a Ii nc L1lldl!r I he ncwly [urnH.:d se,'onc]ary layer anc1 the connection IlC'cumc complete.

IX·10 Ilbck pupa If,/») and temperature I.M. IIAHIZUI(A, Hl47). (;V1W /II), w 11 kll I:; n':;]JIIIl,;ihl(' i'ur tll(' dVPllsit illll or dark pigments in

pllpal illll';';UllIt'IlI, i:; located Oil IT,I positiOIl or XlI-chrolllosome, The gene is wieldy ciistrilwtl'd ,lnlon,\~ <;ilI\WIII"lII raq·~;, c~qlL~cially ill the Chinese univollilll' strains. 'i'u;l n(lS~, wilh til(' wild ~;ilkw()rl1l, Hllm"J'x lItaJUfarinrt shows I !lal /'1' i~ ulso rL's[JllllsiLdc for t Ill) black [lupa of n. 1Il({llriarinlt, which is IU(lhd II 11111 I liS wild IYlll' (Ii' clOlllv;:tit-al.uc\ silkworm.

Tile pi,l(IIH'nlat iUll !InletS,: ill lilt' 1>1at'k JlU [J<L is highly sLlsceptible to Iclll\ll'I'atu\'(' l'llllcliliullS, Th,' lCllllll'ralurv dfC'l'livc p('riod I.T, E, ['.) is rather narrowly limiLed, rallgill,l': 1'1'11111 I ltc' l'lul Ill' S]Jillllill,l~ 10 Hl'vcral hours before [>II]1al i()ll; l'. g" :.!() iI(lIll'S al ~~()'l'. 'I'ill~ dural illn or 1 illl(' lWCl'SSaI'Y Jur il1-ltillitillg tIll' ]Ji,l~lll('nl. rlJl'llI:tlilill l'll<1l1,P:i',; witll llIi! Il'llllJl'ratur~· according to Ill,l;arillllllk CllrVl', 11ll' lligllll' lllL' Il'III]ll'rat 1I1'L~ Iltl' slwrl.l'l' I Ill' liuw, as shown in the tallIl' Iwlow.

llllr:lli'lil til lilli" 1I"I"'",;:Ii'Y IIII' inhiililillg 1111' pi,l';lIlt'111

[mIlI:ll i"ll :iI diffl'i'I'lll 11'lllpl'i'illllrl'~i

11'111[11'1':11111'1'

·111

HI

!I!ill

,11111

11111

(ill

;:0 1'-

"

7

IlJi II ,

ill wall'!'

I (1011 ~:l't'.

~1I1i

,Ill

13

The Lemllcraturc-lillll' r('lati()n~, both ill it dry dl<Lllll)l'r and in llOL water, follow t 1l(~ \.'\Jl'Vt'~: a fkr j\ rrlwll ius' i'lI1'JllU la, in w h kh t he It value for each (,L1rv(~ b IIll a \{'vl'l Ilf :iO,()(I() ral. which is dlw neither 10 the gT()w!h rate llor to t]Ie IIxidatioll lIf ('l1ZYl1lt' hut to heal death of living !Jtdngs or protein coagulation.


Tyrosinase activities of the body fluid showed difference between bP a.nd -/- during the T. E. P. There is no difference, however, in the enzyme activities or in chromogen content of the blood during the period from the ripening to pupation between bp·insects which are kept at 20° and 40'C. during T. E. p" though the former becomes dark-colored and the latter not.

IX-10 Black pupa (bp) and temperature

!!. T..,.ro~int\5C, lctiviLy in blooU during fJrcpupul st~lgc , > ~

,,~ + , @ bP I,P

:WC dLlrillf(I'l';;P dO C durin~r TEr' 3. W~\tCl" 50lublu prolt.:ill in Will,:{ l"Ulidc uf hp pupa,

/I) jllt'l hdorl..' pUllatiull

20'C Juring 30'C during 'tEl' TI,I'

4. "Prol~il1 DL'nuturullon HYPOll1C'shi" as to the of(cet 01 lcrnpcrillurc UPOLl lhe cutic.:ular tnc[~lnin o( insect

WP. wtltcr solubh.l proleIn,

high lemp.

~9'-® , @)-©

WIP, willer jntiOlulJl~ prolein

Water soluble protei n, which is connected with chromog~n, is changed in nature by a high tempera· ture, and it fails to have a chanc~ to be combined with the chr(Jmog~n, l11uking the formation of llwlanin impossible. M. HARIZUKA

Water soluble protein content in the integument just after pupation varies according' to various temperature treatments applied during the T. E. P. Treated over 28°C" the quantity of the water soluble protein decreases. In hot water extract, however, it is not reduced.

From the fneis mentioned above, it is assumed that water soluble protein plays an imporlant role in the pigmentation mechanism giving a site where chromogen sllch as phenols is oxidized by enzyme. A slight change occurs in

nature of the protein caused by high temperature, resulting in failure of the pigment formation and loss of a chance of combining the reactioning system which involves chromogen, enzyme and the water solubler protein, on which the pigmentation reaction may proceed (I-IARlzuKA 1947),

124 T. Yokoyama

IX-.r 1 Differences in pterins in epidermis of several mutants (n. ARUGA

and N. YOSHITAKE'J.

Three kinds of p1.erin an~ recognixablc in tlte epidermis of the silkworm larva: leLlcopteril1, isoxanthopterin and xanthopterin BIT. In addition to these, xanthopterin HI (g,Jn~rally called xanthoplerin .(3) is also formed in the epi

dermis of lemon lTlutant by the recessive lern gene. Much isox<tnthopterin and lellcopterin is contained in the epidermis of Striped (P') larva characterizccl by hlackish marking, and xanthopterin Bj. and 131l is hardly formed in the od-iram;lucent (oel) in which the uric add content ill epiclcnni::l is less than normul.

IX·II r)ilh'l'l:ncl:~i or ~·,tll\1l' ptl'rin,; in epitll'rllli,; of several mutants

p [em P' od i)' tem ad lem

Rf valLie mutant.

x:tlllholllvri II III yl'll(lw O. ,[[i (). ~~:J II

I lid jJ" [em od (om

I

II· I

plerin colur ur , , JIuoresCt'IIl'C i hllla~)uli sudium i

I tll:el)t' i :I,'('lal(' I !

J) [em

I X<lllll1Upl,·l'ill BTl ydlnw \I.,IG \1.·11 , I

I

i su,a III hupl" rill purple) 1I.:I:C II

It'lI"[)ptl'ri II palll bIll,· O. I:!. II

II. AIW(iJ\ & N. YOSllITAKI,

IX I~ Rd1l1i(J1l lJdwCCll ptcrin f()rmation and nil and I)"~ g'L~nl'S (II. J\IWGA).

The ptcrin [ormati(}11 illc[licll~rl11is Ill' tlw silkworm larva was investigated hy LU;ing ()d-l1lotUl'd-trallslLlCl~nt (od'/l l ) and l1loLtll'd-Hlripl~cl (8 '111 ) mutants obtained IJY X-ray treatments. The lllOttkcI-lranslucl'111 is cllaraclerizecl by thc mosaicism between l10rnml and translucent part.s of the inlt~gllml'nl, and is due to the occasional elimination of the fragment or chromosome carrying .\.,,,1 gene during' somal.ogenesis, and mottlcrl-stripccl is characterized by the

appearance of numerous white patches on the black marking clue to the elimination of the chromosomal fragmont carrying p" gOile. The xanthopterin-

Silkworm GenetiC's Illustraled 125

B [ormation in the epidermis controlled by lem gene was investigated by using ad mt lem and Sott lem larvae,

The [ormation of xanthopierin-B was markedly inhibited in the epidermis where od gene expresses its action by the elimination of the fragment carrying -1-°(1 gene in od"" lem larva, and the same phenomenon was observable in the epidermis in which P' gene ads to form melanin pigments, whereas xanthoplerin-B is fonned in the while patches where t.here are no melanin pigm~nt.s, From these result.s it. may be said that. t.he xanthopterin-B formation by lem gene is inhibited by the action of od translucent or p'.

When od,nt anel smt larvae are vitally stained with neutral red, phenomena resembling the formation of xant.hopt.erin-B described above are observable as to the stainability of the inlegument. The epidermal cells in which +oc!

and p genes express their actions are stained in deep color, but those in which oct and P' genes express their actions are not or very lightly stained with nculral reel.

IX-12 RclaLioll between plcrin formation and od, p genes

! motll.d I,"»olu,.nl (odm'l -_ .... _-_.;;{. -----""'.'" -~q'~/~r

" ..... '011

n, moltled .trlped (S.') p

-p~ .... ----,~----~ .. ~-"~

~o\'/ adm' 10m odfI'Lt (8t1I1Tl(!d wlth nLiutrai red) Sm, {em Slftl (fj:taincd wIth neutrnl ,"cd)

I ; ept-M cuticle

cntlo~ culicJc epJ- ''''' <

dermis ,.

II' I .. i.' I ,

)

I

~ H ARUGA

IX-13 Relalions among pterin, uric acid and 11lelallin pigments (H. ARUGA).

There arc somc close relationships among pterin, uric acid and melanin pigments in larval integuments in certain silkworm mutants, St.riped marking controlled by P' gene is imperfect dominant to plain (P), showing darker hlack color in homollygous (P'IP') than in heterozygolls (P'/Pl, On the contrary, the uric acid content in epidermis among three types, P'P', P'P and pp, displays an inverse relation with the case of melanin pigment, i. e. PP>pj)'> P'P'.

lsoxanthopl erin and leucopterin arc contained in the epidermis of plain (P), and in addition to these pterins, xunLhopterin-B is contained in the larva. of plain and lemon (p lem), The relationship between the melanin and pterin

126 T. Yokoyama

IX-13 Relations among pterin, uric acid and melanin pigments (Integument)

1. Relationship between melanin ancl uric acid

substance

quantity of melanin quantity of uric acid uric acid mg/tissue g

type_.

pp

pps II

'fit

2. Relation~hilj between melanin anc! plerin

5.8

3.6

substance I quantity of quantity of pterins

melanin xanthoplerin B I isoxanthopterin t~'p(!

p +1-p lem 1f\. 1-

ps -Ht 'II~

p~' lem "r +1- +~I+

3. Relationship between pterin ancl uric ,It:id -·~SLljjstan(;c~'~·~_-·~· .. ~ ... ~-~-~~i- ---~,--_---_----------_--~~- .. _ -~~~,-., ,-,

- " quantilY of uric· quantity 01 plerins

P

oil

lem

lem od --~- ------_ ..

I acit! uric acid I

mg/tissue g

8. 8

~, G

8. ~

~. ,1

x'lnthopterin B iouxanthoptcrin

-/1

-1-

-111- -I

±~+ ±~+

I eucopteri n

+

+

+

+

Icucopterin

+

+ ±~+

formations has been investigated using p !em and Ii (eJil. In jJ' {em iudi vidual, an antagcinisLic relation for the formation of melanin and xanthoplerin-B in the manifestations of Striped and lemon was observable. Not only melanin formation was suppressed to a certain degree, bLlt the Cjuantity of xanthopterinB also markedly decreased, whereas no quantitative changes in is()xanthopterin and Ieucopterin were recognizable.

The relationship between plerin and uric acid has been clarified by using lemon and ad-translucent ([em oil). The uric acid content in [em od is almost the same as in ad-translucent, but the manifestation of lemon character is markedly iniluenced by od translucent, the amount of xanthoplerin-B decreasing remarkably.

Silkworm Genetics III llstrated 127

IX-14 Studies on pteridine metabolism in insects (S. NBS AWA, • AKAGUCl-n,

T. T.II IRA and M. TSUJITA).

In regard io the mechanism of pierin metabolism in insects such as Drosophila and silkworm, the followIng scheme bas been proposed by the authors:

Xanthopterin B->2 amino-Ll-hyclroxypteridine 6-carboxylic

acid->2 amino-4-hydroxypteric1ine (AHP)->Isoxanthopterin. In both Drosophila and silkworm, an enzyme oxidizing AHP to isoxan

thopierin was found and its nature investigated.

TX~14 PteridinC' metabolism dedllced from the studies of Drosophila and Bomb),x

Cormnol1 all N Pre(lIr<,o, NJ )COOH --t-C -~ I __...,aoiJo .... Red

tv ) b' HnN~N N H~ se, ct Pigment

v, en, etC' t Lahyl Brown Pir;mrnL Yellow Pic;menl

;Y~COOH ~:"'IC:Jy!\.lI H2N~,.l.N~n IIcN~"'jH HO~)'Hl

AHP Xanthir,e

Dehydrogenase __.... t ~ j'Y ___,.t cnPN Acoopto,) N~N"tIl HN>

1-I2N~~lJOI-I O~"':t- 0 Ii H

Isoi:antlloptcrin Uric j\cic]

lVI, TS1:JJTJ\

IX-l S Studies on the maternal inheritance of the yellow-lethal silkworm

(M. TSUJITA).

Maternal inheritance of yellow lethal silkworm is shown by c1iagrammaHcal figure,

IX-IG Excretion of uric acid in translucent skin mutant (S. SHIMIZU).

The crystalline substance precipitated in dermal cells of silkworm iaryae is, in general, uric acid, which is cont.ained much more in the skin of normal larvae than in that of translucent mutants, ill roughly proportional to trans

parency of the skin containing it In both types of the larvae, the crystals of uric acid in dermal cells be

gin to dissolve and Dow out of the cells toward maturation for spinning,

128 T. Yolwyama

IX-15 Maternal inheritance of lethal lemon silkworm

Fcnmic moth

, . ,

.

1 N"rm,'

Iintching

Ydtuw larva (Dies)

---Yst1ll0It

M. TSDJITA

IX-lG Excretion of uric acid in trnn~luccnt skin ml1tant

Uric ncid content in thl:' excrements of matulc larvae

lIinl1ll U:i;:~ normill (2·10 rng/g) ll'ansluccnt (5 lng/g)

TJrie acid (ontl'nt in dermal cclls

nrJrrnal (1(1., mg/rr) tran:JllIc~nt (3 lng/g)

Uric ~cid content in the llrinc or muths

I)ormal (2~H nIsic-) tr~n~hl.;(!nt (5 lUff/g) S. SI-IIMIZU .


finally disappearing at ahout the end of spinning. This change can evidently be shown by chemical analysis of the skin, and it can also be observed directly under microscope.

The difference between the two types of larvae, in uric acid excretion of the Malpighian tube, ill not yet BO large at the voracious period of the fifth age. But it becomes evident at the end of maturing when the crystals in the Malpighian tube (" absteigender Schenkel ") and the acid in lhe excre-111enl are much morE' in normal than in translucent, in parallel with the transparency of skin. The same is said as to the acid content in the urine excreted during the pupal stage'.

Amylase activity

A brief description of the studies carriee out on the amylase in digestive juice and body fluid of silkworm is given in the following with figures from IX-17 to IX-23.

Explanation of Lhe figures

lX-17 Simple test of amylase activity of the digestive JUIce and body fluid. When electric current of high voltage, about 3000 volts, (the amperage

being small) is applied to the silkworm, it instantly vomits digestive juice. Thus the digestive secretions can easily be collected. In most cases, two drops of digestive juice were added to 2 c. c. of 0.05% soluble starch solution.

The mixLure stood at room temperature for 1 hour. For measuring Ule amyloc1exlrinizing power, 2 drops of iodine solution (1/20 N Lugol's solution) were added lo the above mixture, and the colO! thus produced was tested.

When the color lurns yellowish brown, the amylase activity is strong or

lX-17 Simple tc..,i of amylase activity of the digco.tive juice ::Ind body flUld

~ ~ll.-ltJW ~currt.nt high \olt n1l111-Ilmpt.rc

1 amylase activity

(+J

~ amylase activity (-)

-nfter 1 hour at room temp

S MATSUMURA

130 T. Yokoyama

positive (+), but if it turns blue, the enzyme action is weak at negative (-). The body fluid can easily be obtained by making a small incision in one

of thoracic or abdominal legs, and getting the body fluid which drops out. The amylase activity of the body fluid were tested in the similar way to

that of the digestive juice. The author succeeded in selecting four strains which showed marked

difference in amylase activities iIi body fluid and digestive juice. Two strains showed strong amylase activities in digestive juice and body fluid, while the other two very weak or almost negative in both activities.

The results of his experiments which have been carried out since 1924 are shown in the following figures (IX-IS to 23).

IX-IS Genetics of amylase activities of digestive juice (A) and body fluid

(B) in Bmnbyx mori 1. a. Two strains which differ in amylase activities in digestive juice, one

very strong (+), the other very weak (-), can be observed within the same race or among different races.

b. Two different strains in amylase activities in body fluid, as well as in digestive juice, are found within the same race or different races.

c. The strength and the weakness in amylase actions in digestive juice behave as an a11e1011101"ph, according to mono-Mendelian heredity.

The strong amylase action (+) always dominates over the weak (-) as shown (A).

d. The strong and the weak actions of amylase in body fluid also behaves as an allelomorph like the case of digestive juice (TIl.

e. The two pairs of characters, can be represented each by a pair of different genetic factors (genes), that is, the strong ancI the weak amylase

fX-1H Genetics uf amylase activities o[ digestive' juice (A) and body fluid (8) in BO/1Z{IYx mori

~.f:,:,;;~1:J . ~ , I I l1I'jal'

~;;;~ t !m'

-1/(11' ·t /ar tIt

(Ill

k_'·,:::;;"t;l) 'I'

t::i;·~~·Zr·~·:):j t/he

I /h/' -1/"(1 L~_____I

bt'/lie

((e. a gene of negative amylase activity ill digcsl'ive juice. be. a gene of negative amylase activity in body i1uicl. The enzyme activity of heterozygous individual Ulkes an intermediate value of the parents. S. MATSUMURA

Silkworm Genetics Illuslraled 131

actions in digestive juice each by +nc and ae, and those in body fluid each by +br and be.

IX-19 Linkage of the amylase genes of digestive juice and body fluid in Bombyx mod L.

There is a complete linkage in female, and partial linkage in male. The

crossing-over value in male i~l ca. 1%.

I',

IX-19 Lil1kage of the amylase genes of cligestive juice a11d body fluicl in Bombyx mOl'i

r .. x ~~~ I /It'/ ! bit af! t /ttfJ t l-__ ,-__ -'

I,

~ ...... -- •. P,~

, _ __ .G'~~' ~:< _1 ___ '~:" ae b"/(le be

r, 1Z-"'~,4~~.,.b"" (/11 1111 1 I tliJ bll/I bv (It' ('l",I(, I at' (l1/«' II'

\N t)9

Till' l. rtll unr vdluc of hilI ham) ilbl gcm,:'l, ac and be. 1'!J C(l I ~

IX-20 Distribution or Lhe <l.mylase types in variOlls races of Bombyx mori L.

From tire facts as mentioned above, the silkworm can be classified into the following four types as far as the amylase genes of the digestive juice

and body Ilu ic1 arc concc'rned: 1) I_"r I_Ill type, 21 I '''be type, 3) ae+ b8 type, 4) aebe type.

IX-20 Di~lribution of the amylase types ill various ntcc~ of Bumliyx mori L.

"I(l.lI1f'~t UllI\oltlll(! UII11I. ... L UIIl\o!!inc \ lutl Llll.{)Oll 1.ILl \\hIH lll(II{)I\ I ~lL.

. __ J I I

1·lype

"",11 ....ail!!! .... I- un (10 I no be

IT Iype ITlIIM IV type

o Indl,m nluln\olune IIbht

~(_.lIuw r.lu.

132 T. Yokoyama

The amylase test was carried out with 67 Japanese, 107 Chinese, 5 Indian and 28 European races, the results of which are shown in the following table:

Groupe Race n umber of each amylase type

I Japanese univoltine white cocoon (14 races) II Chinese univoltinc whitc and yellow cocoon (45 l'aces)

III Japancse & Chinese bivoltille white cocoon (115 races) IV European llnivoltinc white cocoon (13 races) V European univoltinc yellow cocoon

VI Indian multivoltine light grecn cocoon (5 races)

+ ne be> -I- 'lr -I-b">ae+ '''»aebe +ae +''', ae+'''>+a'be, aebe --I- '" -I' be, -I ne be, (fa I· "'j>aebe ae·j·I"»+""be, liebe, +ae +b" ae -I 'Ir, aebe, +ar +'"

By the app1ication of the amylase test, one can easily differentiate allied races or strains in the same race, which are difficult to discriminate by any other morphological or physiological characters.

IX-21 Distribution of amylase types among the indigenous races in China, France, Italy, India and Japan.

As we arrange the amylase types of 207 races tested in relation to the districts where those races are collected, the distribution of amylase types is shown in the following table.

Districts Italy & France India China Japan

% % % % % Amylase types

+(11 +IJI' '1. 7 10O 30.G 32.8

+(1r' be ~l.2 25.0 3G.I

ae-"!·/lt' 55.5 39. '1 28.8

{Ie be 30.G 5. 0 1.7

IX-21 Distribution of amylase types among Lhe incligenous raccs in China, France, Italy, 11lllia and Japan (207 races te-steel)

ll~d~' & France

Japiln

.......a .......a S. MATSUMURA

'H +b. av+ ac ha

Silkworm Gcnelils Illustrated 133

IX-22 Functional differencc of the digestive amylase among dWerent strains of Bombyx mari L.

The activity of the digestive amylase gene +ae is variable with different races as shown in the following.

Daizo> Ryulmku>Chi nese No. 101 > Koishimaru > Hei >Ch usu>Kojiki .. Ihaku.

On the cont rary, the activity of {(e which concerns with the weak amylase action (almost negative activity) is nearly the same for each race.

The amylase activity of the digestive juice of +ueoe individuals is half as strong as that of 1-'" I ne ones.

F j hybrid hetwecn 1_"" between tli[[erelll strains shows intermediate Of the parents in amylase action.

The variable activity of the digestive amylase in +ae strains may be interpreted by the quantitative theory of gene action of R. GOLDSCHMIDT. If the intensity of the amylase action is controIIed by the quanLity of amylase, and the degrec of activity of the amylase production depends upon th2 +a. gen::~

action, the variability of amylase activity may be attributed to the quantita

tive difference of the +'" action.

IX-22 FUl1ctiol1dl cliffcl'Cl1CC of the digc~tivc amylase among c1 iffercnl sll<tins of Bombyx mon

(

8

7

-780 (I1nl,o) p ~)o( ~

I If I 0'/0. am) lase Dcth Ity 'i 0 aml'lllse act I vl~y 0

a F, ~

" 10. ~z. .. "::.._~~ Ij am) laso nctlvlty 2" 2

1/+ 'HuyJu c ddlVIl~

/'1'> (R) IIk""u) 1 60 I( 103) 1 3'> (L 101) ~ 05 (hul IlIflluru)

-... ~ fJ(l (IILI) '-. ~ j'1i «hu,u) "J 50 (1\IIJdo Ih,11,u)

I(C 103) '~(J 107)

(f 7) '- (C n)

p ~x~ f/J I +i"

"1I11~IU';;c aLtl\.ll} 7 1 amvb">c ncll\Hy.4 4

" ~ nm~ liilbC' r11.1lvlly 6 3

5 MATSUMURA

[X:!3 Amylase activitIes in digestive juice and body fluid in the 5th instar.

a) Di,l',c"live amylase. 1. Enzyme action of I a" larvae is feeble soon after the 4th moli, then

gr,\dually increases in its action until the full growth in the 5th stage and decreases when nearing the ripening.

2. Male surpasses female in amylase action. 3. Through the 5th age, amylase action of oc gene larvae is totally negative,

134 T. Yokoyama

b) Body fluid amylase. 1. Enzyme action of _/_be larvae is feeble at an earlier stage, it increases

gradually in proportion to the growth at the 5th age, but declines again near the ripening stage.

2. Female slightly surpasses male in amyJase action. 3. Through the 5th age, amylase action is totally negative in the larvae

of be gene.

IX-23 Amylase activitil~s in digestive juice and body lluid in Bambyx mm'i --t bl'/ '/It'

-~

1-11 , ........ '--" 0

f, Ii ., ~

d~o'~ in 5th in~,(ilr

1. i\~li ... ·ity (If digL':-.livc ilm .... J:I~c

1.11

.~' 1"~J

.:! ~ O.M '

~ 0.7

§' Illi " O,!j

0,,(

lit 1/1/1' j

-9 ....... .:..

l'"!!-J-T-i;-"G7-day~1 in ;jtll in\;IH

'J .. hi ivit r o( hody 1111111 ,l1nrJ,!,';('

S. MATSlIMl1l1A

IX-24 Genetics of Cal'OicllOid cocoon color

}I ~\

'I . '

\\ ,; mirl ~U! ~i 11q.;lafll!

Schematic figure of pathway of carotenoid permeation

A: carotene %011C C,-carotene) B: x<ll1thopilylls zone (lutein,

violaxanthin, taraxnnthiLl etc.)

M. HARIZUKA

J - ([I-du.), II cr X-L'lu.) .

Yl'IiOW blood 'iuol)' plnin wliite 1>100[1, i ILitilJi{s }'

J II ), yellow blood inhibitor, lTIay bl' alJtolic lo (/

C (XII-ehr.), g;olc1l,n YL"low cocoon ()/ ( II ), pale YL'IIow cocoon cs/( II ). slraw L'olurt,tl ['OL'COL1 Ci ( /I ), yellow intwr layer of

CllC[)[)ll

Above four art' multiplc alleles to white iuner layer I" and mainly COllcern in permcability of :,;ilk gland to xantho· phylls.

F (VI-chr.), ilesh colured, 1'/~ amI Cli, pink and cinnamon-huff, when cocxio;t with 1;:

Aboye three COLlct,rrl in ".carotene permc:ation.


IX-34 Genetics of carotenoid cocoon color (M. BA1UZUKA).

Two main pigments are known in cocoon shell of the silkworm; one is ethersoluble, carotenoid, and the other is water-soluble, flavone. The carotenoid is said to be derived fr0111 mulberry leaves upon which the larvae feed, because there is exact similarity between the carotenoid in blood, egg, fat bodies or cocoon shell and those extracted from the leaves (DIm 1933, MANUNTA, 1033, '35, '37). Really, !1-carotene, neo-/1-carotene B, lutein, taraxanthine and violaxanthine, all of which occm also in mulberry leaves, were detected in cocoon shell (OKU 1933, MANUNTA 1937, HARIZUKA 1956).

There arc ~cvcral kinds of COCOl1 color fundmnente;Ily. Chemical analysis shows that each color has its own cOhstitl.tonts as shown below (Vid. IX-25).

COCOOll layer I

t lrou- I gllllUt , outer'lTIost ollter-, mid- or inner-

pi!Smel1t~ I flavone Icarof~ne CUCOOl} color

blood I cocoon 1------- '. gUile I gene I

while in col()rlc~s a, 1; blood or +1'

while in

any

yellow +"-I-lY: +1"_1 CJ blood

outer yelluw strawculoreu

inner yellow

lk"hcolored

pink:

greell

"

"

"

"

" G/,

C

C't

ct

Flu

PI,F+u

Ott abun-dant

I

++

++

neo-fi- . carotene BI lutein

I

++++

trace + +-1'++

trace ++++

trace -I-

+ ++

tara· viola-xanthine xanthine

++ ++

++ +++

++ ++

trace +

trace +

N.B. 1·,0.1-1.0; ++.1.1-5.0; +++,5.1-10.0; ++++,10.1-20.0; -I- -I- -I -I- • a!Juvl) :!O.l 11115/100 g cucoon ~hell. reared at 23'C during the lasl larval imilar (M. HARIZUKA UJ5(J).

It h; reasonably assumed that genes responsible for the cocoon pigmentation with carotenoid control the permeability of intestinal mucosa and silkgland for the pigment concerned (J uccr 1949). Following this concept,' carotenoid genes of the silkworm are classified into two groups, blood and cocoon, according to the sites where corresponding genes exert their action. -Those of blood group control the permeability of intestinal mucosa to both c!'rQtenes

136 T. Yokoyama

and xanthophylls. Those of cocoon group are classified further into two

groups according to the kind of carotenoid to which they control the per

meability of silkgland cells; carotene group sllL:h as Pf~ and F and xanthophyll

group such as C multiple alleles (viel, VI<-l). Main portion in t.he silkglanel

at which each pigment enters is different. Almost all carotenes enter the

gland at the posterior division. of the middle silkglanc1 called carotene zone and xanthophyll mainly at the middle division of that called xanthophyll zone. As carotenes enter the silkgland at. earlier time of the la~t larval in

star, they advance forward and reach the top of the silkglancl at the ripening

stage and are spun at the beginning of the cocooning. Accordingly, they

always come to the outer layer of a cocoon. While the time of entrance of

xanthophylls is not so simple as carotenes which wa~ hereditarily explained

by IL".RIZUI(A (1956).

IX-25 Effect of rearing temperature condition during the 5th ins1.ar on

carotenoid pigments of COCOon.

WATANABE (1918) repor1.ecl that a rulativ(~ depth of yellow cocoon color

was variable with change in rearing tempc;'rat me during the last larval instar. Ill' concluded that yellow cocoon color bccan1l' deeper with increasing

temperature. Since then the effect of tempcrature conditions upon the process

of development of cocoon color has long been clisl'u:ssed among gl~nctist~ of Bomb),x in Japan.

According to UnA (1\)22), ill Eur()pean yellow COCOOll, flesh color or cream

yellow a[JjJear~ at the ~mrfacc of cocoon at a lower temperature and yellow

at a higher temperature. Ill' insistecl that F Ulesh colon wa~ cjJi~taLic against

Y:I' (yellow COCOOll) at a luwer temperature and vic(! I1I'J'SIt at a high tempera

ture. This was, however, denied hy OUlll~A (H):n) with the explanation that

the fact wa~ attributed tll incol1lplet.e ckvel0pl1wllt 01' llesh color by F at a

high iem peratu reo

I-L'\.Rlz1.IKA (lD[i(i) has estimated L~ach fraction of carotenoid occurred in dif

ferent cocoon layer at different tl'IlIlJL~rat lire and fOllnd that a comparatively

larger W110UIlt of the !Jigmenl was acculllulated ill cocuon shell ilt J:i"C. than

in that at 17.5"C. or at 2S"C. The rate ul' lluctuat iun with lliffcrent Lempera

ture conditions was larger in carotenes of tile ()utcrllHJst layer than in xan

thophylls of outer or inner layer. In olller words, the develuping proce~ses

of carotenes are marc sL1~ceplible to tcmperature conditions than those of xanthophylls. He was able to explain the whole problems nwntionecl above

from the stand-point of the difference of SllSL:l'ptihi Ii Ly ]Jc! wucn both pigments

to temperature and the location of each pigment in (liffel't'.nt cocoon layer.

" At the Lime, Y was not C\ symbol of yellow bloot) gUile as present time, but yellow cocoon.


IX-25 Effect of rearing temperature during 5th jnstar on carotenoid pigments of cocoon

17 S"C JO'C

c I?il II ~ 2~ , I. p"cQroteno

~ 10 I ::;. nI::~:nrotcn. U 1

'" IV. tnraxanthln '" ? ___ n __ ,,-.. [L._ • CL ___ V. vIol •• anthin

" IDWlVV lomwV JOINV IUC Z,'C 30"(

PkF"'lltEJ tWill BfEI

137

138 T. Yokoyama

X. ,Breeding (Including Heterosis)

It is said that silkworm was introduced from China into Japan more than a thousand years ago (X-I). It is not certain whether there had been any aboriginal Japanese race of silkworm before the introduction from China. However, the old Japanese race spins a peanut-shaped cocoon which is different from the usual Chinese one which is oval or spindle in shape.

Most Japanese varieties were white in cocoon color, a few races yellow. They were usually uni-voltine, a few being bi- or tetra-voltine. were usually tetra-molting ones.

For breeding purposes, the egg producers reared the stock strains. times they tried cross-breeding between Japanese and Chinese (X-I).

in the 19th Century European races were also used lor cros::;-brecding.

being They

SomeLater

K. TOYAMA studied hybrid vigor and empha::;izecl the benefits of utilization of it in 1906 (X-I).

X-I History of breeding

Old Ja[JanC5C silkworm r:ll;C~; "riJdnal~'d mainly from

aborigin.1I and Chinc:ic race!:> Int ruduced abOlll I hOll~',HlU

years lI,"~iI, L,ltcr in Hllh Cl.!lltlln' EurujJt:all !'ace!; Wl:n;

<lisa micd for c.:ru~iB·lm.:cdill).{.

1845

1894

1D06

1~11

C··-! 'j1 hivoilinc hy 1. NAICAYAMi\ & ( "_ . .1 ;~ lInivfJllilW j. FUJIlIfI1T(}

- --I ]npilllcsC! ~;lrain by T. KtT~UI';.'\.WA Chinc~ic. ~,trail\

K.'TuYAMA studi{~d hyhrirl vi~~rJr illltl t~mllha:jile"

bcncnl~i (If utilbr.atiun 111' it Tht: Scrh:ultural Expcrill1lmL ~1i\liun, M.A. F.

wa~i 1~~;talJli!jhed ill 1!J11 <11111 :idl~1l1 ilk 1U1:L\UU\ of

hrceuinlr W<I:, acl:qltcd fur L1H! iLlIIJl'u\'l~numl of

Vilrioll!; chilr'H:leri:'lk~; 1)[ ~it{jc.:Ii:, I'tlt:l!~' il:. wdl .n. hyhricJ!:I iUlUl!l~~ lhem

1014 C:J· ~_) A new ~ra of Fr-hybl'itl \Va~; \ltarh!ti

by the guvernment. \Vithln !il!vcral year!; 1!1L7-1!I:!:!

nearly all 5ilkworm n~nrcl'~j adopted FrilyiJrid.

1926 Varil)u~; improved raL:C~i with \;Ir!:n ;:UWHlIIt (If

!jilk :.lUhbtL\lll.l~ iI"tll~ilf(~(1.

ID34. Rat:e!. illJapll'd I'llr !liv!'! '1~ U~,[!:i \\'r:ll: ill't:d: I'. ~!.,

rat.:c~; WJfld lur nlW :,ill .. uf !.lIfH!riul' tJualLiy, 1'1lr

flli.1PIc :,ilk, fur nO~'~IY ~;ill\, for fl:,hillg lilll.~, and raCCn

welt ueJ.lplt.!u Cor rearing in 1I11:,lIi[ilhll~ I:l1\'ironllTt'nl.,

and rilL.:C~" (lu!Jal~ til' whirl! al'l! rkh ill V, Ih

HH5 hn\1\"O'-.!I~ml:n\ ill q\l;llltitr a:i Wt~11 a~i qU;llil), ha:i

been I'eali/.~d and utili t.:uJllinuing advLlnt:ing.

Scientific silkworm breeding began in l~n 1, when the Government established the Sericultural Experiment Station. K. TOYAMA was in charge of the breeding project. Practically all the varieties in the country were collected and the characteristics of each variety were examined. Then, Jt~-hybrids


between any two varieties were tested in their' qualities. The results of the

experiments were published in 1917, in which 156 cases of FI-hybrids were recorded. FI-hybrid is superior to the parent pure races in the rate of development, viahllity and silk production as shown in Figs. X-10 and 11.

In 1914, the government decided to encourage the farmers to reaf hybrid worms by distributing hybrid eggs through the specially organized route. T;l~ pltlnvay of silkworm egg at present from breeders to farmers is shown in Fig. X-1G.

X-15 Pathway of silkworm egg from breeders to Bilkworm rearers

'1~;:-inlltllr;1 EXllCriml'nL ,station, M. A. F.

C)-c::::I 0-0

00

(hreL!d) (trH:~;t:.'

--1.---'1 ~\~lItworlll riln .. ' IJrecdw:l (I hTn~ cd I

\'mt f)l'udul"l.·l':i ~IIHI IlrL'f~(t\ln:d ('xH!>I~l)

commercial egg producers

c:J 0-0 ,0

(rour) (I"OOU'")

silkworm rcarcrs

c::>-eJ - O-CJ 0-0 0-0

(h,-.,,<I) \~:;;;'l') (roar) (produ"") IJfii2) grand· 31 rcprOdt1Ct.ive,.l)gg I'cm"rl~s neaC parent egg o 0 ocommerclal cgil

Chinesc ' {F"hybrld, cgll)

The hybrid silkworm gained popularity among farmers so quickly that it prevailed all over the country whithin about five years since the first dist· ribution, increasing the yield of cocoon per gram of eggs (Fig. X-H).

X-14 Diagram shuwing the relation of the propagation . of hybrid eggs and cocoon.yield

(while circle, spring: bla.ck dn:le, 5ummor-Autuml1)

140 T. Yokoyamll.

The breeders have tried to improve the reproductive races in various characteristics useful in practical sericulture, as well as to and the best combination between them for producing hybrid. Various races adapted for clif[ere11t uses, e. g., good for raw silk of superior quality, for staple silk, for flossy silk, for fishing line, and races well adapted Jor rearing in unsuitable environment, and races pupae of which arc rich in vitamin B~, were bred around 193'1 (X-I).

;; 7ri c 8 8 '0 E " ''ij

"

1

§

g

40

30

20

10

X-3 Increaso in cocoon shell weight

". ". r'~' PrilCtka] hyhrid I'I~arill~~ ~lt<lrt('rJ

- •• -i7i'f.:fi:.;"" -:'*,7.1;-~'ft.;-" -1;;tHo:i7,-:o:, 17,1 -:;"":",,,,"""'71 !:':':'l::"'n -~'J.t:--'~2!J:--~·:i~1 ~':::":'l~~--:":~II';_'~I!I""'~G'1 -y~ars

X-7 Progre:-;s of the raw silk [Jl'H'(.'rtl<lgc of l:(ICllOI1

(Sprillg n!arill~;)

____ years ~.


Every effort was concentrated on increasing the silk production by a single worm, sLlcceeding in raising the gain from about 20 cg. to about 50 cg. during the period from uno to 1950 (Figs. X-3 and 7).

Usually high productive worms are not vigoroL1s. A compromise of the two antagonistic characteristics was attained chiefly by the impr9vement of ih::! rearing method. Through such improvement the increase in efficiency for production of raw silk was resulted (Figs. X-3, 7 and 14).

The effort of silkworm breeding is at present directed to the. improvement of the quality of' fa w silk sLlch as size deviation, neatness, exfoliation and boil·off, decreasing neither quantity of silk nOr viUility (X-Z).. For instance the result of improvement in neatness of raw silk 1s illustrated in Fig. X-g.

X-2 Aims of breeding

1. hluher vleld of l'IlCOfln

2. belll'f rcclnbilHy

o{ ~~aL.:oon

3. Jess deviation hl ~izc

1101Ivicr weight of sIngle COCOO/l and richer lllHWlil}' rl[ sJJk ~lJbtlt;mn.,:

hCIlIthy !iilkworm

unfr.wot'llble one

and grctltcr h:mgth of favorable ono

cocoon filamunt II1II •••• ----

~. uelll'f J1C.lIne~}i

of .~i!k

[j, h.'!'1s lau~lnC!s5

V, 10'. boll·ar{·la'S (IQSS quantity of seridn)

Several examples of practical breeding of silkworm are shown in Figs.

X-1. 5, 6 and 8. SW:UIU, HASIMO'l:O, later TSUJITA, TAZIMA and TAKASAKI in the KUMAMOTO

Branch of the Sericultural Experiment Station started the breeding· of a European and a Chinese race to increase the silk production in 1927 according

142 T. Yokoyama

1

X-9 Progress in neatness of raw silk

(National avtJragc of ca.:h year)

93

92

91

~ 0

~ 90 0

<;

~ if "tl

V~

1 88

1937 '3S '3[.1 1,10 '·17 ·t~:l I,m '50 'Gl 1!j2 '5;; '51 '55 '[16

X-S Selection for length of C()CllOI1 lilanwllt in Chinese racL· ... MK

(IY:l8) gCIlr.!raLions

(1950)

N.llA'fJl.

Silk worm Genetics Illustrated 143

to the plan of Y. TANAKA, This work has continually been carried out, suceeding in increasing the silk production of a single worm from 33,8 cg. (in average) to 70.2 cg. in the European and from 25.3 cg. to 56,8 cg. in the Chinese (Fig, X-5, 5a and Fig. X-6, Ga).

Hybrid silkworms are vigorous and high-productive in silk, but it is difficult for the egg producers to rear the pure races to produce. hybrid eggs. Double cross or half-double cross eggs are more convenient in this point, because the parents for the production of commercial double cross eggs are

.<l 1< ~ .. :;: .5i

< 0:

rJ <Il

j ]

l<:

Ul

(:! 0 0 u 0 U

'+< 0

v bJJ ro ...... (:! v u

'""' Q)

Po

Q)

.<=: '-'

'""' 0 '+< (:! 0

'';:; u OJ

OJ Ul

V

~ OJ

'""' :;j Po <J.)

.<=: f-<

i K

144 T. Yokoyama

already hybrid and easy to rear and the number of eggs laid by one moth is also large. Half-doublc cross eggs were first distributed by the governmcnt in 1925 and double cross eggs in 1911G (X-141.

:!tll

Hill

X-5 ProgrcCls in cocoon qualities by [lL1re line: sclcL·tioll

A. l~l]rl.llj(';1Il ran', n]o

~IIII

1911

1t:11

/I

II

:' .. ~ .... ~.:. !, ,:\ /

••

............. "4· ". , ......... ~. "/"'" \ •••• :: \ / '.. ~., •••• r

••• ,'" '-........ I ," .," ',.' """~'~~v.: r: ",-="" "

.r-/ .. ,,;'~/ . ' A'~"'~;'<- "

.' . . . . ... ~, ........ \:"

:/ \ ... .~ .' '.

" 'I" I I

._'.1 \:' ...... ,

" .' I

, ,< ,

.. " 1 ... ,_/ \. , ".,'

l'iLllflllr 11ll' wl'il:hl ofa l'fll'()(lll ~;hi!)I' from 100 Cfj,',lq',) til :~11 ~'j'!'1 \1,,1'.') 111 Olll . \1'11111 tllll (~7.:1 rg) 1(1 ~!:i7 (lit (i ~')',' ill tilU

"f tlH' (',h:(IP1\ :11(,11 rail,,' (ruin 1(111 ll:l.-;" .... ) III lliH (:!ti.:1~l';) in 010 {nml 1110 (If I. :1.",,) to 1m (~!h. :!~",) III 1ilU

(If Ilw wdEdl! III ~I pupa ~ from lOOp. ~):l}:) III tIl) (!!. I:! /1) ill 010 IllIlil 11111 (1 ·Plt'.) Illl~':.! (I ~~!II.) 1I161U


X-5a Specimen showing the progress in silk amount of cocoon, a EuropeaI) race 010

145

146 T. Yokoyoma

X-6a Specimen showing the progress in silk amount of cocoon, a Chinese race 610


HeterQsis in silkworm'

If we plot the value of anyone characteristic of FJ hybrid against that of mid-parent vaille, we get a linear relation between the two, e. g. in the cocoon weight lhe relation is expressed according to the formula:

'y=O.826x+O.609

when~ .y is the cocoon weight of FJ hybrid and x is that ot mid-parent (X-IO).

X-IO Cocoon weight of Fl hybrid and its mid·parent value (spring 1944) ..... g __..,

230 ~~

E /~O'B2G'+D ~ ~r: ~ ::; ;:i ::; ~ nY

j

'" ./ j. l:: ., .:;:.. ii

Observed F,·hybrld Valu .. (x)

_/.:)/ ~ ... : ~.;,:~;. :T . H ~ 1.70 / 11.P' ":::,: , ~ .---+ct:hctcrosis,F\-M 1. 7 r::.;0.83 3 t..:- /' __ M:mld·parenlv"lue

..... 1',: F,.hl'brld j 40 nx 1 1133 6810BI5 $,1.l0131l4 43 3122

I,U J 70 2.00 g

mld.parent value C. HARADA

X-ll Hybrid vigor expressed 111 various charactetil:ltics

Ion

80

fiU

4U

20

(The figure In parenthesis shows the absolute villu~)

% or Yield of cocoon wt.!ight of w(,light of monality fram 10.000 hatched c.Oi,oon shell sIngle cocoon

lilf'-,I!!

21 7%) (l7.3 kg) (405Lg) (U8g)

(31 5 cg (! 18 g

(13 51<g)

(122%)

o pnrQnlsF, hybrId P 1', p r, P F,

C. "ARAPA

148 T. Yukoyanta

In X-ll the absolute values of heterosis in variOllS characteristics in economical races, mortality, yield of cocoon from 10,000 ants, weight of cocoon shell and weight of single cocoon are shown to be \12.2% (PI): 21.7% (P)), (17.il kg.: 13.5 kg.), 140.S cg.: ;11.5 cg.) and (2.0S g.: 1.78 g.) respectively (X-ll).

Very interesting two examples are shown in which the silkworm with particular gene shows <l remarkable degree of heterosis. The one is K gene (X-12) and the other is 1'1 gene (X-1:~).

X-1:! lIt't(']"osis l'Hl1:>I.'(\ by gent.' (K anel m/» action

knobbed normal

i,'!II:OC!1l wt. C-J

11)0

r!'tl:;:i 11\'('t'~, (ru!'>s O\'(~l"S

U:'~",J .11 "''' I LJli:Nl 11.-C ___ ) C_)

111) J LU

~

(:) 120

T. IIIIWUt~

K I kno\)h('c\ \ is :t )~'-~\\t' !tl~':lkc1 ill n.() posit ion !In Xi-chromosome. There

is ano[her ,[;,cne JIl/' <I[ :!.l.() Oil I he' S;lI1H.' ch rtJllHlSUI11 e. IImUlm made comparison Iwlween ,I dilTt~rcllt comilinationS!lf li](' I\V() a!)()v(' menli()ned gene!"> and their alleles, and found Ihal (11(' ('()l'IHlIl wl'i,(~;llls w('re arnll1,l(,ecl jusl in the order of degree or hf'ler(),l.!;l'lll~ily or gelll' l:()11lIJinali()1l, i. l~.

1 / + //IN 111/' J 00

-1- /I\_ Nil>! ))Ij.> I 1.1 () 1/1 mN I I IK 111/)/1 1~(1

Recessive trillloiting rt i!"> a ,~'elll~ on Vll chl"oJ1)o!">omt'. If 1'/ is concerned ill Fj-hyhrid, the heterosis ('xpn'ssl~cl in !">Udl cJwractcrislic as cocoon weight or COi._'oon shell weight, especially ill the lattvr, is remarkably hig-h, i. e. 17()-190?;; and :!()G<':~[i;)'; respectively, in contrast to the ordinary F( cases which

ShOWl~d 103-1:25 anc! 105-125 in the respective characteristics (X-U\),

SJll(worm GCJ1CliLS Illu~1 rated

X 13 Heterosis caused by rt-gene

P!gurcs are ShOW11 in index for 100 of the mid parent value

F,-hybrld of 1'/ x +

Ordinary cases 01 F:L"J1_lbricJ

cQcoOn woighl

~ 170~190

cocoon shell weight (;)

lOS~ 125

In [0\ progeny of l't)( +, heterosis of oocoon shell{ h~ mote remarkable than that of pupa-weight. The fact may be explained a~l follows:

In tt, the recessive Lrimolting', silkworm eliminates the 5th instar of normal 11.h moller, the silk production is pOQr all compared with lhe l1orm,ti. F, individuals of rtx+ beconie '1lh moIler regaining the last in$lat, during which eill{.gland gl"OW remal leabl y.

T. }Imom;;

COCOOllS Exbibited

Before the Mdji era (1792-1867)

149

150

X-17 Kinko

X--19 Koishimal"ll

The Mciji era (18()S. H118)

X-21 Holdren

X-23 Nihonllishiki

T. Yokoyama

X-l8 Matamukashi

X-20 Scihaku

X-22 Kuniic)1i

X--24 Yamatonishiki

Silkworm Genetics lIlustrated 151

Early period of the Sh5wa era (1927-1950)

152 T Yokoyama

x :jG ]!) CIO:i X-:Hi Tailwi >' Chaan

Presenf time Varieties for spring rearing (Llpp~r t w() arc parents, lower F,)

~ ,

':11>-, ~

,p,

~ , .. r\!! 1

~ iii

-....., i\_

. ., .~

~ ,

~ \ \ , .. r

.~.-"

X-37 ]122;< C12~

SilkWOl"Dl Genetics Illustrated i5S

X-39 Hoko X Shingyoku

154 T. Yokoyama

Varieties for summer and autumn rearing

X-tlO Sh i1ka x Giti1"ei

X-41 J122 x ell5

Silkworm Genetics Ilhlstrated

Varieties especially improved in lousiness-free charact~r1stic

.. ,:1···

.~ ,

X-43 J501 x C502

156 T. Yokoyama

X-,14 Scnsh u)< Bunko

Silkworm Gelletics Illustraled

XI. Uelation between the Sill{worm-races and the Pathogenicity of Muscardines

157

There are many diseases in the silkworms. However the recent advance in the study 011 the muscardines, especially such topics as their species specificity and the difference in pathogenicity of differcnt varieties, including difference in resistance oj' the silkworm races, arc 'rnost interesting. About 150 species of l11uscardine which arc panisitic all various species of insects are known in Japan, and ~tbOllt 20 of which are (;ound attackiL1,g silkw0rm. They are 110t only different in the pathogenicity on different species of insects but also different in the time lag between the infection and the appearance of symptoms. In the C~IG~ of muscardine which has a long time lag, di~iIl~ective

treatment whe:1 the ~:ymptoms are observed is little effective. lL is, therefore necessary Lo clhinfcct 2.S early as poss:ble. This principle in rnuscardine dIs" infection contributed very much to stabilize the cocoon crops in the district where sllch a C]Llcasc ,~t, grec;h-lTIuscardine with long latent pEriod LS prevailing.

XI-l Mllscarclines <lttacking .silkwo1"rrLs

Whitt' ll111';,'"rdine

(/it'(/I/l'('}'irl i'llssiall'l (BAl.».) VUJI.I..)

GreGll I1ltlscal'ciine (Spicaria /)raSi12a (MAUBL$.) AOi{l)

Yellow mltsG~(rdjl!e

(lsi/ria /arillosIJ (PICKS.) FR.)

Satllma fungus ,l1irsutella satumaensis AOlU)

158 T. Yokoyama

XI-1 Muscardines of silkworm and other various insects (1936-1950)

XI-2 Relation between the pathogenicity of l11uscardines alld the kind of insects

j nocllllllll

-cOncel1trat16ri oC" i noculating-spuresllspem,ion nurilber of spores in 0.01 c. c. uf inuclIlating:sporesuspension ,-_ .. -----_,_.--

Ilumber of insect inoculated

diseased insects

si lkworm

kyo~o-lly

pyral iLl· mulh

Bealll'cria bassi{[J1({ Ilsaria jllmosorosea I Isaria /arillosa I "check

lo-:~F- :ll~ :-1(1: 1 :100}0 1:1 I 1 :100 il~ :11 1 :1 :101 1 :~OO I-

I! I' : I- ~11H 1 1- -I -I 27t1 i I- -I

I ' 1 0 i 10 1 (J 10 ! 10 H) 10 lO lU

HI 10 10 10 ! 1I 0 () (} [i 2 0 0 o 0 0 0 0 to 10 III 10 7 5 ·1

., ,J

2 o I :1 o i, o I IO JO 10 10 I

o

Remark>;: (1) lnscds teste',ll: silkworm (-1111 slage larva), kyoso (pupa), pyralitlmull! (5lh stage larva)

(2) Tl~mjJerature and humidity during the experiment period: 23·-~ 27·C., S5~100%

(3) Inoculation: O.ll1 c. c. of RIJore suspension was inoculalecl Oil indiviclual insect

The pathogenic activity of white- red- and yellow-muscardine (Beauvel'ia bassiana, [saria fumoso-l'osea and [saria farinosa respectively) is the highest

Silkworm Genetic.;; Illustrated 159

in the host on which they are the most frequently found in nature, namely in the domesticated silkworm (Bombyx mori L.), Kyoso-:fiy-pupa (Stu,1'mia smicariae C.) and pyralicl moth (Mal'garonia pyloalis W.) respectively (XI-I, AOKt et ~l. 1951 a, XI-2, AOKI et al. 1951 b).

The p:tthogenicity of white-mllscardine is different according to the races

of silkworm (XI-3, AOKI et al. 1951 b.) XI-3 Relation between the pathogenicity of white-muscardine and silkworm

races

Table a.

silkworm· race Mus. 1 NU5/C108 N112xC 110

conccnt"ratiolJ of 1 .

i11oculat!ng·spore· 1 :111 :100 1 :1~~ i 1 :200 I cl:~~~i 1 ~~ I ~ :~~~ ~:~·;o c~Ck --........... I ----.. ~-- --.. - --.sll~pensl0n I

number of spores i 11 0.0] C.c. of spore· ·f sllspel1Hion

number of 1 10 silkworm tested

5 daysli --G 10

~ I diseased silkworms after the inoculation 10

~)

I

11. I

10

total 110 j 1() ~.-~.-.--.----.-~ .. -" ... -.- _ .. -

6

<1

1U

2

4 4

10

286 164 \

10 10 I +

10 ! 10 i

I

5

286 164

10 I 10

Remarks: (1) Silkworms tested: 5th stage larva immediately aiter ecdysis (2) Temperature and humidity during the experiment period: 26°~

2S·C., 95-100%

Table b.

10

o

silkworm-race . N 115 . C 108 I N 115: C 108

concentration .of il~(;.cul~tin~·l! 1:1 i~ ~;~I ~:;.0011·=. 11!-.1-.:~.-.1~ :1011~.1~~1-=- .. 1 :1. ;·:~~.·.1 ~;~-.O 1.···.-=-spore·suspenslOn . . __ '. ) i. 1 ..... ___ __. I _. .._ .-- -- 1 .. __ _

number ol--'spores in U.Ol c.c.1 I . I i I ! I 'I

~~lsi;l::~~i~:~ii1g.spore- I I· + 259! -- ! + I .~ L25~ =-.1 :~ I ~ I .~~~. =-.

:::':::: '~i1 :";;;~7-tc't:"- ::~ I ::: ~:: I~j~: I ~ I:: ~;;t~c ':: 1~ "---... - ---- ---_.- --- ....... -." ....•. ~-----,-.. ---.-.~---,,-____..----.

Remarks: Temperature and humidity during the experiment period: 26 Prv213P C.,

75,...,100%

IGli T. Yokoyama

The pathogenicity of white-, red- and yellow-muscarc1ine to the various races of . siH::worm, Kyoso-fly-pupa and pyralid moth respectively is directly proportional to the germination rate of conidia. the growth rate of germ-tubes and the speed of cylindrical-spore formation of the causal fungi in the host's blood in vitro (XT-4, AOI\:[ ct ai. 1951 b).

XI--4 Relation between the germination of conidia in the insect blood and the species of 111uscarclines or the kind of insects

llU;cct bloocl I silkworm I

nlu~.;car .. I dines <C llSJN 112 C 1101

kyosll-lly Mus. 1 N 115

.. l';c·rminat ion I

length of while 2·1 l<i

I

13 2

germ luhcs red II 2 ., 2 32 " (1) Yl·llnw K I) I G 13 L I 1

white \18 \lG \12 16 p;l'l'l1linati n,l( rL'" .'?is 11 ],I 12 87 rate (:l) yellow (j\) !iii 5:~ 73

furmatiull of while HI- -H- ·11-cylindrical reel tIf sporl~S c::) rd!u\\' I I -I- -Iff

XI .. !) l'atllll.!I;elli,~ily of 1l111scanlilll'~; of ~i!kwllrm, illld lllll;;t.'ardinc;~ a((:lt:king variuus ;11;;(,,:1;;

A Il c

(A: !\111~;, I, .':; NlI:i 'Cllti, C: NIl:! "ClIll:

l:~ hr:,. incuhation) (c)

(Al (0)

llir:;llli!lla );([llflll!l~'llsi~ AnKt 1.11\ ~iill{.\vurrw. (1\)

Jl~,Yt:hhl'H: (B) " T ... ytlifmlrhl/rmlitla lC)

(,\) (11)

it"

(El

A B

C;n~~'n IIHt!iCitnlilH! UII ~iill.: wurllW {\

NuctuitlilC B

Yellu\V IIlU:,CiHdilll: 011 :;iIli.wOnll~, (t\) (A) (B) I _

l.h'l/lifO/U}jUIil !lj'l'{·/,thili,'j Oil J\l:Ll1lidilt.' (C) Ct'ramIIYI'illal! (1») Pnalid Illoth (E)

[sllr;tl il.';llmflCJl.~is Aot';'I

1111 ~jllk\vllrJwj (A) lIlad. 1I\\1~'\',\r'\iHI: /Jijlriml nij)prmicll (B)

(01l"/!1I1"11 di".,/rw/rJr METCH.) K. AOlU

Pyralid-moth

3

32

17 24

77

-I-

tl~


XU. Wild Silkworm

Here are presented following wild or semi-wild silkworms found in Japan.

Bombycicleac

XII--l Bombyx mandd1'i11(t MOORE (Kuwa-ko in JaI)anese). Food plants: Morus. MosLly three generationS a year, hlbertlatioll {;\$

eggs. No practical use of cocoons at presel1t in Japan. Iudoor-breeding of larvae is difficult. '

Saturniidae

XII-2 Ant/zetaea yamamai GUERIN (Japanese Tussah Silkworm. Yamamai in ,Japanese).

Food plants: QU(:'rCltS acutis-sima, QUernts_sel"rata, GC!J!taneq c,r;e'l,Zcr;ta, . .. On,Q gen,Qrattan. a YQ.at, ht\)C!tn.atlcm, ae, Q.gg'O.. CG<:G0.1J.S. 8X~ l'lt8.c.lkJ.!J.ty lJ.~...d

as materials [or expensive silk cloths. Moslly field breeding On QztfM:US acutissima, in Nagano prefecture: '

XII-3 Anlizeraea pemyi Guj1iluN (Qhinese Tussah Silk:worrn. Saj{INan in Japanese).

Food plants: .il!!.qrczts ac~~~~iltJ,a, fil, S,ql'J.,~. acr4fc4 ~'I ;ger¥Cfr.ta,lw~ Castanea crenata, Sqlix ll.imitzalis b .~Two generations a year,) nlbefnai.iQn as

~pupae. Cocoons are used as materials of sllk clc!)tl1s. Mostly no practical breeding in Japan now.

XII-t! Phi!osamia cynthia pryeri BUTLER (Sinzyu-sat1 in Japanese). Foods plants: Ailanthus glandulosa, Picrasma qzlassioides, Pheltodendl'on

mnurense. Two generations a year, hibernation as ptlpae. Cocoons are used

for spun silk.

XII-5 Philosamia cynthia ricini BOISDUVAL (Eri-Silkworm. Hima-san in Japanese).

Food plants: Ricinus communis, Ailanthus gtanciulosa, Ilex integm.

Polyvoltine. Cocoons are used for spun silk.

XII-6 Dictyop!oca japonica MOORE (Kuri-ml1si in Japanese). Fooel plants: Castanea c1'enata, Ginkgo biloba, Ci1'lnantollum camp/lOra. One generation a year, hibernation as eggs. Cocoons are materials for

spun silk.

162 T. Yokoyama

Larvae of wild silkworms

XII-l Bombyx mandarina MOORE

XH-3 Antherrrea Pern.1'i GUERIN

XII-5 Philosamia cynthia ricini . BOISDUVAL

XII-2 Antizeraea yamamai GUERIN

XII-I! Plzilosamia cynthia PI)'I?I"i BUTLER

XII-6 Dictyop/oca japonica MOORE


COCoons of wild sllkworI\1s

.x II 1 PlnlosamlCl ~yutlua XII-·5 Phllosamlct cynthza XIt-6 Dz¢tyopl(!cCl Japol1ica, /n I'erl BUTLrR rZClI1t B01SDUVAL MOORE

Silk and cocoons of Vi lid ~!lkwollns

IG4

.w

XII-l BOn!hyx mandarina

Moorm

XII-4 Phi/osamia cynthia pryeri

BUTLER

T. Yokoyama

Moths of wild silkworms

XII-2 Antlzeraea ),amamai GUI~lnN

XII -5 Plli/osamia cYlltflia ricini BorSIJUVAL

XII 3 Antlieraea pe1"12yi

GUERIN

XII 6 Dictyop/oca japollica

MOORE

Silkworm Genetics Il1ustra~ed

XIII. Genetics of Mulberry (incllldhig food plants of the Silkworm otlier tlian Mulberry)

165

OSAWA (1916) found that triploid mulberries prevailqllite widely in Japan among practically useful varieties.

Afterward he obtained tetraploid (XIII-5, 6) plajl.ts [rom the hybrid between the triploid (XIII-2, 4) and the diploid Clm-1},

SEKI (1951) discovered that MOl'Zts titiaejolia MAKINO is hexaploid CX:1II~3).

XlII-I, 2, 5 Chromosome type at mi!.taplUlI:lC or cell division in ovary tissue of nlll)berry

XIII-l diploic! XIII: .. 2 triploid xnr~5 tetraploid

XIII··3, 4, 6 Microscopical preparation of root Lip cell of mUlberry I

XIII 3 heJ{aploid XUI-4 triploid XIU-6 tetraplOId

Thel ear.:: about 1000 mulberry var~eties in JapaJ1, about 200 of them being practically cult.ivated. The Sericultural Experiment Station M. A. F. ~ucceeded in breeding 3 varieties of high productivity (1949): Kokuso No. 20, K, No. ~1

166 T, Yokoyama

and K, No, 27, and bas been distributing the scions thereof for grafting to the farmers,

As for the distribution of mulberry species in Japan; Morus bombycis is found in the northern districts, 1'v1. multicaulis in the southern districts and M, alba in the intermediate region.

In the exhibition, there are found polyploid mulberry trees, various mutants, mulberries under breeding, popular mulbeny varieties, other food plants of the silbvorm including Cudrallia jrll'allensis, C. triloba, Broltssonetia Kajinol?i, Ulmus sp" Rosa sp., Lartuca Smriola, L. r/!mticulata, L. dmroglossa, L. laciniata, 7'amxaclt1n pIa tJ'C({l'jmm , 11denoplwrrf I'Pr/idlfata, CryP/o/ aenia canadensis.

Another interesting demonstration to be shown is a technique by which artificial crossing of different mulherry trees can be carried out easily. When

XIII 7 Usual method of artificial crossing in mulberry tree

1. Branches an~ !~n"'I~I{lpcd with

[Japer llag priur to "lu:i~;{/millH

r) PoJlcn~i are t',oin~: t l.) Ill..!

Xl1r Sa Posl-harvest-jlollination

TIle procedure is as fo!loll's:

1. The cuttings (If l-year-olt! ~hoot;; an' stured at cole! temperature of ~,5~5, U"c.

~. Tlwy are. 1 hen, Lntl1sferrl'd to a Warm trawl' ill :;~"C.

fur growlh, 3. Tlwy arc able to blo;;solJ1 amI bl~ar k'rril'H. 4, Thus the artindal cross pollination 011 the cutling, re.

suIting in SCl~t! production, is possihk t llrollgllUul the year.

Silkworm Genetics Illusttated

XIII··8b Cllttings arc ready [or blooming at 25·C. left; Wit]1 female IJoWI,'!TI, rigllt: wJth male flower.s

X III 8e Shoot blooms and QellrS 1)l!!tries at any season by the procedure

lG7

168 T. Yokoyama

a branch or shoot of mulberry is made cutting in a pot at 25°C. after a cold s~orage of about 30 days, it blooms and bears berries at any season of the year (XIII-8) (SUGIYAMA 1951).

In the exhibition there were pictures of practical crossing techniques, pollen-gun, isolating envelope and propagating nursery (XIII-7), as well as the pictures of male and female flowers of mulberry (XIII-g).

1)

2)

3)

1)

2)

3) 4)

XIII-9b Floral diagram of mulberry

o o

,(~) .,.,<~.:c.-

~,~~-.-~ ..

The exhibition also included live plant with pot as follows:

211 Pot No. 1 Pot No. 2 Pot No. 3 Pot No. 4

3n Pot No. 5 Pot No. 6 Pot No. 7

6n Pot No. S

311 Pot No. g

Pot No. 10 4n Pot No. 11

Pot No. 12 Pot No. 13 Fot No. 14 Pot No. 15 Pot No. 16

5n Pot No. 17 Mixoploicl

Pot No. 18

Polyploid mulberry Natural diPloid and polyPloid

]ushima (Monts bombycis K.) Ichinose (Mortls alba L.) Kairyajumonji (Moms alba L.) Rosa (Morus latifolia P.) Akagi (Monts bombycis K.) Shimanouchi (llIo1'lts alba L.) Fukushimaaha (Moms allia L.) Keguwa (Mo}'zts tiliae/olia M.)

Induced Po(vploid No. 3604 (48) (411? >,211 0)

c (Lla ',1 :< 211 0 ) Tok Ll 42 (311 ,;' y, 2n 0 ) 23CN4, originated from2n seedling treated with colchicine. 23Ck3, originated from 2n seedling lrealec1 with colchicine. 27CE, originated from 2n seedling treated with colchicine. b (6n q ;( 2n 0 ) S (twin from 211 seedling) a (4n<;Jx611o)

23CRy4, originated from 2n seedling treated with colchicinco

Silkworm Genetics Illustrated IB9

170 T. Yokoyama

Pot No.8 Kcguwa (ill P()i No.!) No. 3(iOl (-1S) :3;1 Put Nu. 10 C 3n

Pot No. 11 Toku 43 411 Pot No. 12 23 CN1 lIn Pot Nu. 13 23 CKa '111


Pot No. 17 It 511.

172 T. Yokoyama

Improved new varieties

Pot No. 19 Kokuso No. 20 (Naganumax Garyii), high-yield, suitable for KantO district.

Pot No. 20 Kokuso No. 21 (NaganumaxTsukasaso), high-yield, suitable for the southern district of Japan.

Pot No. 21 Kokuso No. 27 (Naganumax Kairy6nezumigaeshi), high-yield, sui-table for the middle district of Japan.

Pot No. 22 No. 18, cold resistant. Pot No. 23 No. 14, resistant to blight disease. Pot No. 24 Tani No. 10, resistant to blight disease. POi No. 25 Tani No. 2775, resistant to blight disease. Pot No. 2G Tani No. 2830 (2), resistant to blight disease. Pot No. 27 No. 19, an early budding variety. Pot No. 28 Hata Fl (Okinawaguwax Shiwasuguwa), suitable for subtropical

region. PoL No. 2~J Kairyiiichinosc (fchil1o.sc>::Shir()J1lero~5), suitable for Kumamoto

Prefe.cture anel t1w regioll of similar climate.

Put No. 19 Kukuso No. :.W Pot No. 20 Kokuso No. 21


Pot No. 23 No. 14

174 T. Yokoyama

Pot 1\'0. ~(i Tani No. 2830 (2)

Pot No. 28 Hata F1

Pot No.:2.1 1':0. 1\1

Pot No. 29 Kairyaichinose

Silkworm Genetics 11lustraictl

Popular varieties

Pot No. 30 Kairyonezumigaeshi, a widely distributed variety in Japan. Pot No. 31 Ichinose. a widely distrilm1.ecl variety in Japan. Pot No. 32 ShUkakuichi. Pot No. 33 Tomieso. Pot No. 311 Kairyoroso, suitable [or western Japan. Pot No. 35 Kairyoakameroso, suitable for western Japan. Poi No. 36 Kenmochi, suiLable for snowy region. Pot No. 37 ]ushima, suitable for snowy region. Pot No. 38 Nekoyatakasl.lke, suitable for snowy region. Pot No. 39 Ichihei, an carly budding variety.

Pot No. 31 Ichinose p,)t No. 32 Shukakuichi

175

176 T. Yokoyama

Pot No. 3:-) T(lJ11ie~1i Po! No. 3-1 Kairyoroso Pot No.;J(i Kenmochi

Pot. No. :{S Kairyoakame·roso Pot No.:-37 Jnshima Pol No. 38 Nekoyntalwstlke


Pot. No. 30 Kairyanel.tuuigaeshi Pot No. 39 . Ichihei

Mutants and malformation

Pot No. £10 Kibajiimonji, yellow leaf. Pot No. 41 Shimpaku, chlorophyll-free in shoot tip. Pot No. 42 Garyii, branch winding. Pot No. 43 Shiclareguwa, drooping mulberry. Pot No. 44 Marubaichinose, an entire-leafed mutant from a lobed variety. Pot No. (15 Chijimiguwa, shrinked leaf. Pot No. 46 Mozaikuguwa, resembling mosaic-diseased plant. Pot No. 47 Itoguwa, deeply-lobed leaf.

177

178

Pot No. 40 Kiln. ju lllunji

]>01 No. ,.W Shiclarl'guwa

1'. Yokoyama

I'ut Nu. ·11 Shillpaku PoL No, 112 Garyil

Pol No, 4-1 Maru]Ja·khinoHu


Chijimiguwa

Other food plants of silkworm

Trees

Pot No. 48 Cudrania javanensis TREG.

(.Moraceae)

Pot No. 49 Cudrania 11'iloba TIBe. (Moraceae)

Pot No. 50 BroZ{ssonetia Kajinoki 5mB.

(Moraceae)

Pot No. 51 Ulmus 8p. (Ulmaceae)

Pot No. 52 Rosa sp. (Rosaceae)

POL No. 48 Clldrania jaitJrmonsi'6 r·

180 T. Yokoyama

Pot No. 49 Cudrania triloba I-I.

Pot No. 51 Ulms sp.

Pot No. 50 Bl'ouSSol1etia Kajinoki S.

: •. \ ;1 ..

".

Pot No. 52 Rosa <lp.


Herbs

Pot No. 53 Laduca Scariola L. var. saliva BrSC}IOFF (Compositae) ,

Pot No. 54 Lactzeca clenticulata MA~IM.' (Compositae)

Pot No. 55 Laciztca clracogtossa MAKINO', (Compositae)

Pot No. 56 Laclzeca laciniata MAKINO (Compositae)

Pot No. 57 TaJ'axacu!n plalycarjJwn DAHLST (Compositae)

Pot No. 58 flclenoplwra verticil/ata FISCH. (Campanulaceae)

Pot No. 59 Cryptotaenia canadensis D. C. var. jaj)onica MAKINO (Umbelliferae)

181

182 T. Yokoyama

-p".'\" to ?\~

/" I, J iJ' • l.f,AfjIo, iffJ

c:.;.\of,;H· ~".f

PuL No. R!l Lat'luca /r[l'illi~t/a M.

t\' ~ N \' ',~ i T.I ,'," ~ .1,' II 1/1 pk'i/ ,:I'{1,Uli 11,...,\:,'

.: JI.l.\I~" • tor

~. '~,,~ \

:to .. Pot No. 57 Tara.tacztin jJ/atycarpum D.

\

\ / \. ,

I'u! Nu. [j~ JUIJJl(}j'/WYlI ,'eylidllata F.

Pot No. 5~) CrYi'totacmia cClnadensis D. C.


Bibliography

AOKI, K, e( aI., 1951a J. seric. Sci. Japan 20(5) ---,1956b Ibid. 20(G) ARUGA, II., 1939 Bul!. serie. Exp. Sla. Japan 9(G) ---, 1942 J. seric. Sci. Japan 13(5) ---, 1944 Ibid. 15(1-4) ----, 1951 Ibid. 20(1) ARUGA, II. and S. WADA, 1954 Agric. and Hortie. (Japan) 29(10) BOUNIIIOL, J. J., 193G C. R. Acac1. Sci. 203(5)

183

---, 1953 Transactions of the IX international COngress of Entomology (Am~ terdam (2)

FUKUDA, S., 1940 Proe. Imp. Ac. Tokyo 16(8) ----, 1951 Ibid. 27(10) ---, 1955 Ziklwn Ii:eitaigaku Sago Toronkai KocnyClshi (Fukuoka) FUKUDA, T., J. KIRIMURA, M. MATSUDA and T. SUZUKI, 1955 J. Bioeh. 42(3) FUKUDA, T., 195G NatLlre 177 ---, 1!l57 Ibid. 180 GOLDSCIIMID'l', R. and K. KATSUIG, 1927 Bio!. Zbl., 47 ---, 1928 Ibid. '18 ---, 1931 Ibid. 51 HARlZUKA, M., 1940 J. sorie. Sci. Japan 11(4) ---, 1942 Ibid., 13(1) ---, 194.7 Bull. seric. Exp. Sla. Japan 12(5) ---, 1948 J. serie. Sci. Japan 17(1-2) ---, 1956a Ibid. 25(2) ---,195Gb Jap. J. Genei. 31(10-11) llA,\EGAWA, K, 1943 J. seric. Sci. Japan 14(1-2)

---, 1950 Gizyulsu·Shiryo, Ministry Agric. and Forest. Japan (29) ----, 1951a J. serie. Sci. Japan 20(1) ---, 1951b Froc. Jap. Acad. 27(10) ---, 1952 J. Facul. Agric. ToHori Ulliv. 1 HAsIMoro, B., 1929 Jap. J. Genet. 11(3)

---, 1933 BulL serk. Exp. Sta. Japan 8(7) ---, 1934 Ibid. 8(9) ---, 1941 lbid. 10(5) IIATAMUI~A, M., 1943 Ibid. 11(3) ---, 1!l49 J. selic. Sci. Japan 18(5) IlIROBE, T., 1939 lap. J. Genet. 15(2) IT!KAWA, N, 1944a Jap. J. Genet. 20(1)

---, 1944.b Ibid. 20(3) INAGAMI, K, 1955 J. agric. Chemist. Japan 29(12) JUCCI, C., 1932 Boll. di Zool. 3(1) ---, 1949 Proe. 8lh. into Congr. Genet. KATSUKI, K. and T. AKIYAMA, 1927 Sangyo·shimpo 35(406) KAWAGUCHI, E., 1928 Z. Zellforsch. 7 ---, 1!l33 Cytologia 4(4) ---, 1934 J. seric. Sci. Japan 5(2) ---, 1935 Sapporo Noringakttkaiho 26(126)

184 T. Yokoyama

---, 1935 Kagalm 5(8) ---, 1936 Fac. Agric. Hokkaido Imp. Univ. 38(2) ---, 1937 J. serie. Sci. Japan 8(2) ---, 1938a Cytologia 9(1) ---, 1938b Ibid. 9(2) KAWASE, S., 1956 Jap. J. Genet. 31(10-11) KIKKAWA, I-I., 1937 ZooL Mag. Tokyo 49(10) ---, 1941a Ibid. 53(10) ---, 1941b Genelics 26(6) ---, 1943 Bull. seric. Exp. Sta. Japan 11(3) ---, W44 Ibid. 11(6) ---, 1950 Gakujutsugcppo 3(2) ---, 1951 J. serie. Sci. Japan 20(1) KlKKAWA, II., Z. OGITA and S. FUJITo, 1954 Kagaku 2'1(10) KIM, ].. 193!:J J. serie Sci. Japan 10(2) KOBAYASHI, M., 1957 Bull. serie. Exp. Sta. Japan 15(3) KOGURE, M. and N. KOBAYASHI U)28 Bull. Naganoken serie. Exp. Sta. Japan (2) KOGURE, M. 19:13 J. Dept. Agric. KYLlShu Imp. Univ. 4(1) KOYAMA, N. and S. TANAKA, U)5G J. Facul1.. Text. and Sericult. Shi118hu Univ. (6) KOYANAGI, T., 1938 Bull. Seric. Exp. Sta. Japan !:J(4) MACHlDA, J., 1929 Z. Zellforsch. 9(3) MANuNTA, c., 1933 Boll. Suc. Ital. BioI. spero 8 ---, 1935 Atti Soc. Nat. Mat. Mudena (6G) ---, U)37 BolL Soc. Ital. BioI. sper. 12 MATSUMURA, S. 1934 BulL Naganoken seric. Exp. S[a. Japan (28) ---, 1951 Bull. Serle. Exp. Sta. Japan 13(10) MIYA, K., U)55 J. Serk. Sci. Japan 25(3) MUROGA, H., 1948 J. Serie. Sci. Japan W(3-4) N.~.KA(_J, Y., HJ52 Jap. J. Genet. 27(5-G) NAKAO, Y, TAZIMA, Y. and SliGIMlIRA, '1'., 1954 Ibid. 2D(4) NA.wA, S. and T. TAIR.'\., 1956 Ann. Hep. Natiunal Inst. Genet. (6) OIW, M., H)2f) Bull. 1\gric. Chem. Suc. Japan 5

Hl30 Ibid. G --~, 1932' Ibid. 8 ---, nm Ibid. \) OMURJ\., S., Hl38 .r. Fac. 1\gric. HokkaicHl Imp. Uni v. 4() (4) SA.IU.l; Dem, B. and M. TSlIJlTA, H)511 1\nl1. H.ep. National Inst. Genet. «(j) SAT(l, II., Sanshikailw (383, 384, 386, 387) ---.. Hl2~l .IC1p . .I. applied Zuol. lC:~-'l)

---, Hl,l:l Ibiel. (i(4-G) ----, 19·12 Sallshigakll·~assi 14(1) SCIIARH ER, E. and B. SCHARHER, 1 Dfi4 Recen t Progress in Hormone Research, Proc.

Laurentian Hormone Conference (10) SHIMIZU, M., 1955 C. R. Suc. BioI. lt1~l

SHIMIZU, s., 19'1:~ Bull. Seric. Exp. Sla. 11(3) SUGIYAMA, T., 1951 J. Seric. Sci. Japan 20 (2) TAI{ASAIU, T., HMO Bull. Serie. Exp. Sta. ~)(g)

---, 1943 Jap. J. Genet. 19(1) TAKASAKI, T. and Y. TAZIMA, 1944 Jap. J. Genet. 20(3) TAKA,SA,I<I, T., 1949 Ibid. 24(3-4)


TANAKA, Y., 1916 J. ColI. Agric. Tohoku Imp. Univ. 7(3) ---, 1927 Gakujulstt·Kyokai·H6koku (3) TANAKA, Y. and E. KAWAGUCHI, 1932 Jap. J. Genet. 7(4) TAZIMA, Y., 1941 J. seric. Sci. Japan 12(3) ---, 1942 Jap. J. Genet. 18(1) ---, 1944 Bull. seric. Exp. 5ta. Japan 12(2) ---, 1951 J. seric. Sci. Japan 20(1) ---" 1953 Ibid. 22(3) TAZIMA, Y. and M. MIK!, 1955 JaP. J. Genet. 30(4) TSUJITA, M., 1955 lap. J. Genet. 30(5) TSUJITA, M. and B. SAKAGUCIlI, 1952 Ann. Rep. National Inst. Genet, Jap!ln 2 ---, ---,1953 Ibid. 3 --- ---, 1955 Ibid. 5 TOYAMA, K., 1902 Bull. CoIl. Agric, Tokyo Imp. Univ. 5(1) ---, 1906 Ibid, 7 (2) WATANABE, K, 1918 Bull. seric. Exp. Sta. Japan 3(8) ---, 1919 Ibid. 4(2) WWGLESWORTrr, V. B., 1934 Q. J. M. S. 77(2) WILlJIAMS, C. M., 1946 BioI. Bull. 93

Supplemen.tary Bibliography

AIWGA, II., 1939 BllII. seric. Exp. Sta. Japan 9(6) ---, 1940 Ibiel. 9(9) ~-, 194.3 1biel. 11(4) CIIlKUSJII, H" 1938 J, seric. Sci. Japan 9(2) KAWAGUCllI, E., 1936 J. sedc. Sci. Japan 7(2) OSAWA,1., 1916 Bull. seric. Exp. Sta. Japan 1(4) SAKATA, T., '194.3 J. serle. Sci. Japan 14(3/4) SEKl, Il, 1951 J. seric. Sci. Japan 20(1) SUZlJIO, K, 1929 Jap. J. Genet. 4(3) T AJ(ASAlO, T., 1947 Silkw. Inform. Servo (2) TANAKA, Y., 1943 Sangaku T AZIMA, Y., 1938 lap. J. Genet. 14(3) ---, 1943 Bull. seric. Exp. Sta. Japan 11(5) ---, 1943 ]. seric. Sci. Japan 14(1/2) --- "uel OTA, N., 1952 Jap. J. Genet. 27(5-6)

Errata

page -·--~----lin~-----------T- for ·---~;·e-a'_d~---~

--.1 -----______ .. ________ ~ ~ _______ 1, Preface 24

12 19 on p'

14 Plate II

15

27 29 29 29 29 2~)

36 36 36 36 37 38 38 39 39 39

39 39 39 39

39 39

40

8

II-110 19 20 21 22 27 19 20 21 22 13 12 28 19 23 between 24 and 25, to be added

26 30 34 between 34 and 35, to

II-32 no-glue (Ng XII-D. 0)

(!-sp) +'

1+' , +' +' +'

! +P' +P' +P' .+P' ze f

Ys, straw (body cQlor)

UB'

(serosa color)

be added i 36 I (body color) 38 NNs, new no-sta.rs

(::jkin marking) 21 (1938)

of pS (The same correctibn y/ill be made in all p' hereafter.), left fig. of the lowest rqw is unfertilized eggs bearing no number of exhtbition II-32 no-glue (Ng XII-D.O) (no picture) (l-sp) +0 +0 +0 +0 +0 pI p~

pS

P' Zef

Yr (skin marking} unr

(color of chorion) XVI-chromosome

lu, lustrous (eye color) cts, cheek and tail spots

(skin marking) XVII-chromosome

Em, black moth (body color of moth)

bt s, brown head and tail spots (skin marking)

OW, waxy translucent (skin character)

(to be omitted)

" elp, ellipsoid (egg shape)

(skin marking) or, or translucelft (skin character) (1936)

2

page

40 42 47 47 50 52 53 53 55 55 55 55 56 56 56 57 .58 59 eo 61 62 66 68 72 72 75 75 75

75 77 78

79 S7

91 92 92

93 93

98 98

100

----- -_ ----l;;~------ --- T' -- ... -----------------,~~------.-- -_--_._-

... --!.-for

27 Plate III 5 6 8 Plate V-l, upper fig. Plate V-3, title

" Table V-6

10

I (1928) I III-9 I Z+Qd I i Z+Od j , were

I X-ray dcse

, does ! 84.4 1 : pMpSY i dil.psy

conc.pSY

pMY

Suzuki '39 21 . jP' 27 ' Tazima '52 16 pY 3 cryptal

I Plate V-ll (a), title Alianthus , 1 V-ll

(1927) III-6

I 2+od

, 2+O(l

was X-ray close dosis 84.4 r pMpSY

I dil.pSY

I cnnc.p8Y I pMY

, Suzuki '29 pSa,-2

read

, Tazima & Ota '52 ;py I cryptol I '. Ailllnthus i V-ll(c)

13 character character, Plate V-I4, upper part W-PSa(W'-I-PtY'PS"t Y , W-PS'a(W.+l'+Y,psa+Y) 22 Further, mo, Further, 1110 1 I1I0/mo/mo;- mo/mo/mo/ +

Plate VI-9, title Hereditary changes Changes Plate VI-9 embryo lethal embryonic lethal 8 , monstar monster

10 • A The Plate VII-ga, explana- • Black and red + Blac1{ and recl marked with + tion

" fl (recl) 15 if the treatment Plate VII-ll, end of. before death. explanation 7

! Plate VII-I5b i

6 12 Table VIII-I, right column, 1st row Plate Plate VII-2, right fig. 1 3

11~

70 days. [<;11/+ £'ll/EII characterizes (LOS f. C.,

. lelt

~VII-2 of ESC: brain

(KOBAYASIIl 1958) nondia pause with

6 + in the treatment before death (C).

70 days (C), . Ell/+ : or Ell/Ell I characteri~e

(I.OS f. c . left

~ VIII-2 ESC: brain-

(KOBAYASIII 1957) l1on-c1iapause in

3

~e-I~~t; vni'?s:_ H"EC~~::\2- ~ --I{"'~A WA, ,:-d--~--~ 106 i 11 I rl is I rt larvae is 106 I 21 ! trimQltings I trimolting 106 I 21 tetramoltings: tetramolting 107 i2nd line from the last trimoulting I trimolting 108 28 acid, such I acid, Such 109 ! Plate IX-I, last line by a mutant by a mutant gene 112 ! Plate IX-4, explana- (+Xrb) spots : (+Xrb); spots

upper row , II tion of left fig. in the !

112 Table rX-5 (1) I C I 3-hydraxykynu- I C I 3-hydroxykynurenine ! Tenine I

113 113 115 118 U8 118 119 119 119 120

120 123

125

I 2 ' s-mottled , S-mottled Plate IX-Ga, title s-mottled 'S-mottled 1 • normal one I white one 9 ' individual individ uals 9 15

I 10 • 4=112 i 17

,lone I (sm,)

lk

I Plate IX-9b, title of ' (smt)

lower row 5 p" Plate IX-lO, explana- I which is connected

, tton with I Plate IX-12, upper delation

part

ones (sm,)

K I +K r sm'

(sm,)

+p : which is to be connected with i

• deletion

126 Table IX-13, 3. 2nd quantity of uric acid i quantity of uric acid mg/tissue column uric acid mg/tissue g ! g

127 9 ' yellow-lethal ' lemon lethal 127 11 , yellow lethal , lemon lethal 130 6 ' four strains four kinds of strain 131 Plate IX-20, explalla- i oivoltine • bivoltine

tiOI1 of 2nd fig. from right in the 3rd row

132 upper table, V ! European univoltine European univoltine yellow yellow cocoon cocoon (15 races)

133 11 FJ hybrid between FI hybrid between

133 134 134

134

last line· Plate IX-24, left fig. Plate IX-24, explanation of left fig.

+ae between ae gene larvae

I }.

xanthophylls zone

Plate IX-:?4" explalla- + 0

tion of right fig.

ae larvae y xanthophyll zone

____ • - •• __ • ___ O, •••• _ •• __ ...... .

p;g~--r-··--·- line I for

--i35·--titi~·-Oftable _- ······1 ~~co;~-~~·ior f~~d~~"

148 148

149

158

158 160

168 175 175 176 178 179 181

: mentally 3 Plate X-12,

I

I single coocon ~re left fig. micropteral ...

of 1st row Table X-13, 4th of explanation

)ine I In rt, the recessive I trlmolting, silkworm : white- red- and I yellow-muscardine

last l'me :. jumoso-rostdt

1

Plate XI-5, explana-! Dendmlimum tion of 2nd fig. from : left in the upper row ; 23 23Ck3 ~7 ill) Pot No. 36 Pot No. 41 Pot No. 46 Pot No. 53, explanation

Kairyoakamcroso Kenmochi Kenmochi Shinpaku Mozaic-mullJerry sCCll'iola

read

fundamental cocoon color

single cocoon, are micropterous

In rt, recessive trimolting, thE silkworm . white-, red- and yellowmuscardine fumosorosea Drmdrolimus

i 23CK3 : Kairyoakameros6 I Kemmochi I Remmochi • Shimpaku I Mosaic-mulberry

Sea rio/a