1194 GENETICS: GRIFFEN AND BUNKER PROC. N. A. S.

size of the Cotton effects, in accord with the aforementioned hypothesis. We havealso brought about a destruction of the pertinent conformations by metal ions, suchas Zn++.The titration from helical to unfolded forms appears to be reversible to the extent

that bases, such as piperidine, can be used to bring the weakly rotating solutionsformed by the addition of, say, trifluoroacetic acid back to the large amplitudes ofrotation characteristic of inherently dissymmetric chromophores. However, thefull initial amplitude of rotation could not be recovered (only about a third for piperi-dine and trifluoroacetic acid). This point and others will be discussed further in alater paper. We might just note here the very strong analogy between the helix-open chain (geometrical) transition in the urobilins and the helix-coil transition inpolypeptides and proteins. Conceivably, the particular conformations of the uro-bilins play an important role in their in vivo biochemistry.

* This work was supported, in part, by a grant from the Alfred P. Sloan Foundation (AM), anda contract between the Research and Development Command, Surgeon General's Office, U.S. Army,and C. J. Watson whose advice during the course of this study and preparation of the manuscriptis gratefully acknowledged. The authors are indebted to Miss Mary Weimer for excellent tech-nical assistance.

t Fellow of the Alfred P. Sloan Foundation.1Watson, C. J., J. Clin. Pathol., 16, 1 (1963).2 Gray, C. H., The Bile Pigments (New York: John Wiley and Sons, 1953).3 Lemberg, R., and J. W. Legge, Hematin Compounds and Bile Pigments (New York: Inter-

science Publishers (1949).4 Gray, C. H., and D. C. Nicholson, J. Chem. Soc., 3085 (1958).6 Gray, C. H., P. M. Jones, W. Klyne, and D. C. Nicholson, Nature, 184, 41 (1959).6 Moffitt, W., and A. Moscowitz, J. Chem. Phys., 30, 648 (1959).7 Moscowitz, A., Advan. Chem. Phys., 4, 67 (1962).8 Moscowitz, A., Tetrahedron, 13, 48 (1961).9 Moscowitz, A., K. Mislow, M. A. W. Glass, and C. Djerassi, J. Am. Chem. Soc., 84, 1945

(1962).'0Newman, M. S., and D. J. Lednicer, J. Am. Chem. Soc., 78, 4765 (1956)." Moscowitz, A., S. Charney, U. Weiss, and H. Ziffer, J. Am. Chem. Soc., 83, 4661 (1961).12 Condon, E. U., Rev. Mod. Phys., 9, 432 (1937).18 Djerassi, C., Optical Rotatory Dispersion (New York: McGraw-Hill, 1950), chap. 12.14 Cahn, R. S., J. Chem. Educ., 41, 116 (1964).16Lowry P. T., R. Cardinal, S. Collins, and C. J. Watson, J. Biol. Chem., 218, 641 (1956).

THREE CASES OF TRISOMY IN THE MOUSE*

BY A. B. GRIFFEN AND M. C. BUNKER

THE JACKSON LABORATORY, BAR HARBOR, MAINE

Communicated by C. C. Little, September 18, 1964

The frequent description of trisomics in humans, particularly for chromosome 21in cases of mongolism and for a member or members of the "D" group in otheranomalies'-3 clearly indicates that viable autosomal aneuploidy may not be acytogenetic rarity in mammals. On the other hand, it is notable that viable autoso-mal aneuploidy has not been observed in the mouse. The present account is thefirst formal report of such aneuploidy for this particular mammal.

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The simplest aneuploids are the monosomics and trisomics. These may originatethrough either nondisjunction or the failure of pairing at meiosis, resulting ingametes which are characterized by whole chromosome deficiency or whole chromo-some duplication. A zygote formed by the union of a normal with a deficientgamete has a diploid chromosome count of 2N -1 and is monosomic, while thatwhich is formed from a normal and a duplication gamete is 2N + 1 or trisomic,for the particular chromsome involved.

In the course of radiation studies which have been partially reported elsewhere4male mice from a stock designated as BN, having the sex-linked dominant Bent-tail on a C57BL/6J background, were subjected to testicular irradiation and weremated to C57BL/6J females. For each male the matings were continued untildeath, new females being provided periodically. From these matings, 6139 F1individuals which survived to maturity were tested for sterility and semisterilitythrough mating to C57BL/6 individuals of the appropriate sex, the matings beingmaintained for at least six months. Among 659 sterile and semisterile F1 males,six cases of apparent trisomy were found through cytological studies. For three ofthese, two of which were sterile and one semisterile, the cytological information issufficiently complete to indicate the presence of an extra whole chromosome orprimary trisomic.

All cytological studies were carried out upon Sudan Black B squash preparationsof seminiferous tubules, made by the method described by Bunker.5 Both sper-matogonial metaphases and primary spermatocytic metaphases were used. Typicalfigures and spermatogonial karyotypes are illustrated in Figures 1 and 2, whosecomponent photographs will be mentioned as 1, 2, 3, reading from left to rightacross the top, 4, 5, 6, reading from left to right across the second row, and so on.

Sterile male 2177 was sired by irradiated male 123, which had received 350 rof X rays 95 days previous to the date of the insemination. Cytological indicationof the anomaly was first observed in first meiotic metaphases (Fig. 1, parts 3-5),where an unusual "trivalent" regularly appeared among the usual bivalents ortetrads. Arrows on the photographs indicate the triple bodies, whose componentsseldom lie conveniently in the same focal plane and therefore are difficult of il-lustration. Direct visual microscopy clearly shows the components to be com-pletely similar in size and morphology. Many spermatogonial metaphases (Fig.1, part 1) were available for determining the chromosome count of 41 and for makinga karyogram (Fig. 1, part 2). With the components simply arranged in the orderof decreasing length, repeated measurements indicate the extra body to be one ofthe elements which ranks fifteenth in size. In Figure 1, part 2, and in the otherkaryograms, the XY pair is arbitrarily given the last position and provides sharpcontrast for the adjacent smallest autosomes.

Sterile male 3887 was sired by irradiated male 153, which received 700 r of X rays168 days previous to the date of conception. At meiotic metaphase I the trisomicgrouping often appears in chain form (Fig. 1, parts 8 and 11; Fig. 2, parts 1 and 2);it also appears in the form of a ring-with-a-tail (Fig. 1, parts 9 and 12), a configura-tion which Blakeslee6 found to be common for primary trisomics in Datura. Sper-matogonial metaphases again showed 41 elements (Fig. 1, part 6); and karyograms,exemplified by Figure 1, part 7, placed the extra body as one of the chromosomeswhich ranks eighth in size.

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1196 GENETICS: aRIFFEN AND BUNKER PROC. N. A. S.

Is~~~~** ***'X*At

**.**.&*W

*~ ~*:*e..8

,Xt,~~~~~~~~~~~~~~~AOE -xpX a. a. ..... . .~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.......

s 77........l.,

FIG. 1.

Male 6537 was sired by male 138, which had received 700 r of X rays 466 dayspreviously, and was semisterile. Immediately after mating, male 6537 sired alitter of three and a litter of four; thereafter no further offspring were produced inrepeated new opportunities for mating. None of the offspring survived to maturity.In this case the trisomic group frequently appears in chain form, but one meiotic

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...**.. *. e.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.....I.S. IyS.

AS .........FI. 2

meahservalda acesr oya loned ydo ver sml sie(i.2

.................

... ......_

mic group in position 18,next to thesmalt...

smle sizs. ic bot meoi nodsunto an asynapsi are well-kown^icrete a t src hea w l chrtaft

.~~~~~~~~~~~~~~~~~~~... Bar...

nietaphase~~~~~~..revealed..an.acesr bod as......a lon dya of.............ver small..size (Fi. ....

part 6). Karyograms prepared from spermatogonial metaphases placed the triso-mic group in position 18, next to the smallest.Discussion.dThese three cases of trisomy plainly indicate that viable autosomal

aneuploidy occurs in mice as well as in humans, at least for the chromosomes ofsmaller sizes. Since both meiotic nondisjunction and asynapsis are well-knownconsequences of testicular irradiation in many organisms, these phenomena mightbe credited as the source of the supernumerary whole chromosomes but for the factthat all three cases were derived from irradiated spermatogonia rather than fromirradiated spermatocytes. Among the possible kinds of radiation damage whichmight produce whole chromosome duplications in diploid gonial cells, perhaps thesimplest is that of temporary centromere damage which causes sister chromatidsto pass to the same pole and, upon the eventual completion of centromere separa-tion, to exist as independent normal elements of the nucleus in a condition ofprimary trisomy.

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1198 BIOCHEMISTRY: RASMUSSEN ET AL. PROC. N. A. S.

The absence of closed-ring figures at synapsis, such as are characteristic ofsecondary trisomics in Datura,6 suggests that none of the mouse trisomics are ofthe secondary or isochromosomal type. Similarly, no evidence has been found, inthe form of alternative synaptic partners of different morphology, which shouldcharacterize tertiary or translocation-type trisomics.The ever-increasing use of human karyotypes in clinical investigations and the

rapidly progressing cytogenetic studies on the mouse may be expected eventuallyto indicate which members of the respective chromosome complexes may becomeinvolved in viable aneuploidy. It will be of particular interest to learn whetherchromosomes other than the smaller ones may be involved.Summary.-The discovery of three different autosomal trisomics, which are classed

as the primary or whole-chromosome type, indicates that autosomal aneuploidyoccurs in the mouse. Two of the trisomic individuals were sterile and the thirdsemisterile; no external deviations from the normal phenotype were observed.In each case the trisomy involves members of the smaller chromosome classes.

* This investigation was supported in part by contract no. AT(30-1)-2113 from the U.S. AtomicEnergy Commission, and in part by U.S. Public Health Service research grant C-4362 from theNational Institutes of Health. Major components of the X-ray equipment and generous super-vision of its assembly were provided by the General Electric Co.

1 Patau, K., D. W. Smith, E. Therman, S. L. Inhorn, and H. P. Wagner, Lancet, I, 790 (1960).2 Patau, K., E. Therman, D. W. Smith, and S. L. Inhorn, Hereditas, 47, 239 (1961).3Uchida, I. A., K. Patau, and D. W. Smith, Am. J. Human Genet., 14, 345 (1962).4 Griffen, A. B., in Proceedings of the International Symposium on Effects of Ionizing Radiation

in the Reproductive System (Pergamon Press, 1963), p. 175.5 Bunker, M. C., Can. J. Genet. Cytol., 3, 355 (1961).6 Blakeslee, A. F., Smithsonian Inst. Ann. Rept. 1930, p. 431.

PARATHYROID HORMONE, ION EXCHANGE, ANDMITOCHONDRIAL SWELLING*

BY HOWARD RASMUSSEN, JAN FISCHER, AND CLAUDE ARNAUD

DEPARTMENT OF BIOCHEMISTRY, UNIVERSITY OF WISCONSIN, MADISON

Communicated by R. H. Burris, August 19, 1964

The addition of parathyroid hormone to isolated liver mitochondria produces anincreased accumulation of magnesium and phosphate,' a release of calcium andhydrogen ions,2 and a stimulation of respirations These changes are similar tothose produced by the hormone on renal tubular function :4 the retention of calciumand hydrogen ion and the excretion of phosphate. In addition, the hormonepromotes the excretion of potassium.5 For this reason it became of interest tostudy the effect of parathyroid hormone upon potassium exchange in isolated mi-tochondria, and to correlate changes in potassium movements with respiration,magnesium and phosphate uptake, hydrogen ion evolution, and mitochondrialswelling.

Experimental.-Mitochondria were prepared fronm rat liver anld suspended in 0.4M sucrose to give 2.5 mil of suspension per gram of liver.' They were used im-

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