1. Introduction

Shrimp culture has expanded and intensified rapidlyaround the world during the last two decades. The develop-ment of nutritionally complete shrimp diets is necessary forfurther intensification of this industry in years to come, andknowledge of the shrimps nutritional requirements is essen-tial to achieve this.

Shrimp, like all crustaceans, require dietary lipids, oneof the three main classes of organic nutrients, along with car-bohydrates and proteins. Lipids represent the most concen-trated source of energy of all, supplying approximately 9kcal/g, about double of that contributed by either carbohy-drate or protein (Mead et al., 1986). Research efforts are stillfocusing on gaining a better understanding of the metabo-lism of lipids in crustaceans, as well as on establishingrequirements for essential lipids throughout their life cycle.This paper reviews the role of essential fatty acids and phos-pholipids in shrimp nutrition, and published data concerningtheir requirements. We also describe some available sourcesof these nutrients with potential use in the formulation ofshrimp diets.

2. Essential fatty acids

Fatty acids (FA) are among the most common lipids;they are long chain carboxylic acids that occur in manydiverse forms, with variations in the degree and kind ofbranching, number of double bonds, presence of other func-tional groups, and chain length (Kates, 1972). Most of thenatural saturated FA have unbranched structures with aneven number of carbon atoms and no double bonds.Monoene or monounsaturated FA have in general an evennumber of carbon atoms and one double bond. FA with morethan one double bond are termed polyene or polyunsaturatedFA (PUFA); if more than three double bonds are present theyare generally known as highly unsaturated FA (HUFA). FAmay be designated by trivial or systematic names, or by theshorthand nomenclature recommended by Holman (1966),which designates chain length, number of double bonds and

the position of the double bond nearest to the terminalmethyl group, whose carbon is designated as the omega ()or n carbon. Among PUFA and HUFA, one can recognizethe n-3 and n-6 families (Table 1).

Burr and Burr introduced the concept of essential fattyacids (EFA) in 1929. The group of EFA is composed ofPUFA and HUFA of the n-3 and n-6 families, which are nec-essary for normal physiological function in animals andman. Their essentiality lies not only in their physiologicalimportance, but in the fact that, like many vitamins, theycannot be synthesized de novo by the body, they must beobtained either directly or as partially elaborated precursorsfrom the diet (Willis, 1987).

EFA play a major role in the biological function of thecell membrane, not only in its formation and integrity, butalso in modulating membrane fluidity, enzymes, ion chan-nels, and receptor properties. They also act as precursors inthe synthesis of hormone-like molecules known aseicosanoids, a group of oxygenated products derived enzy-matically from 20-carbon PUFA (Yehuda et al., 1997).

2.1. Linoleic acid

Linoleic acid (LOA) belongs to the n-6 family, and it isa precursor for n-6 C20 and C22 polyenoic acids formed byelongation and desaturation processes carried out byenzymes (e.g., FA synthetases, desaturases). Oils rich inlinoleic acid include soybean, safflower, sunflower, walnut,corn, cottonseed, pine nut, sesame, and groundnut (Padley etal., 1994).

2.2. Arachidonic acid

Arachidonic acid (AA) is an important fatty acid of then-6 family. It can be produced from linoleic acid, its majorprecursor, by alternating desaturation and elongation steps:18:2n-6 18:3n-6 20:3n-6 20:4n-6. It is a major con-stituent of membrane lipids and the principal precursor ofeicosanoids, which in turn may lead to the production ofprostaglandins (e.g., PGE2, PGF2, PGD2, PGI2),

Volume 2, Number 1 Priscilla Shirley, Editor-In-Chief Summer 2004

THE ROLE OF ESSENTIAL FATTY ACIDS AND PHOSPHOLIPIDS IN SHRIMP NUTRITIONMayra L. Gonzlez-Flixa*, Addison L. Lawrenceb, Delbert M. Gatlin, IIIc, Martin Perez-Velazqueza

aDepartamento de Investigaciones Cientficas y Tecnolgicas, Universidad de Sonora, Rosales y Nios Hroes s/n, A.P. 1819 C.P. 83000, Hermosillo, Sonora, Mxico.

bTAES Shrimp Mariculture Project, Texas A&M University System, 1300 Port Street, Port Aransas, Texas 78373, USAcDepartment of Wildlife and Fisheries Sciences, 210 Nagle Hall, Texas A&M University, College Station, Texas, 77843-2258, USA.

*Corresponding author. Tel: +52-662-259-2169, Fax: +52-662-259-2197; E-mail: mgonzale@correom.uson.mx

Technical Bulletin

thromboxanes (e.g., thromboxane A2, thromboxane B2) andleukotrienes (e.g., leukotriene B4, leukotriene C4).Thromboxanes and prostaglandins are known to cause vaso-constriction and platelet aggregation (Clandinin andJumpsen, 1997). Leukotrienes function in constriction ofbronchial airway musculature, vascular permeability, and ininteractions between endothelium and white blood cells.These conjugated trienes are formed in response to immuno-logic and nonimmunologic stimuli (Mayes, 1993). Thuseicosanoids regulate many inflammatory and hypersensitivi-ty reactions (Clandinin and Jumpsen, 1997). Eicosanoidsmay also modulate the activity of ion pumps (Freeman et al.,1990), K+ and Ca2+ ion channels (Schweitzer et al., 1990;Schwartz et al., 1992), and neurotransmitter uptake andrelease (Templeton, 1988).

AA can be obtained from dietary sources such as veg-etable oil and meat; it is found in small quantities (0.5-1.5%)in lard and tallow oils, liver meal, salmon oil, pollack liveroil, cuttle-fish liver oil, short-necked clam oil, sardine oil,skipjack oil, squid liver oil and herring oil (Tacon, 1987).Though rare in the plant kingdom, it can be found in somemosses and ferns, and is a major component of some marinealgae.

2.3. Linolenic acid

Linolenic acid (LNA) is the major fatty acid of plantleaves, stems and roots. This essential fatty acid is the pre-cursor of the n-3 family of HUFA (Klenk and Mohrhauer,1960): 18:3n-3 18:4n-3 20:4n-3 20:5n-3 22:5n-3 22:6n-3. The most readily available source of -linolenic acid is linseed oil, which normally contains 45-60% of this acid (Padley et al., 1994).

2.4. Eicosapentaenoic and Docosahexaenoic acids

Eicosapentaenoic acid (EPA) and docosahexaenoic acid(DHA) are found in unicellular marine algae, brownmacroalgae, in moss cells and in many animal tissues (e.g.,retina, brain). In general, marine fish, shrimp and molluscoils are rich dietary sources of these n-3 EFA; oils whoseEPA and DHA content constitutes over 20% of the total FApresent include cod liver oil, cuttlefish liver oil, short-neckedclam oil, sardine oil, skipjack oil, shrimp head oil and squidliver oil (Tacon, 1987).

3. Fatty acid requirements in shrimp

Crustaceans have a limited ability for de novo synthesisof the LOA and LNA families of FA (Kanazawa et al., 1979a,Kayama et al., 1980); consequently, they require a dietarysource of EFA. In early studies, Kanazawa et al. (1977, 1978,1979b, c) demonstrated that Marsupenaeus japonicusrequires LOA, LNA, EPA and DHA as EFA, with the n-3HUFA being the most essential, followed by LNA and byLOA, respectively. Several authors have reported qualitative

requirements for EFA by different shrimp species likeFenneropenaeus indicus (Read, 1981), F. chinensis (Xu etal., 1993), Penaeus monodon (Catacutan, 1991),Litopenaeus stylirostris (Leger et al., 1985), and L. vannamei(Lim et al., 1997). However, quantitative requirements havenot often been reported. Kanazawa et al. (1979d) suggestedthat a combination of EPA and DHA should be included at anoptimum level of 1% of the diet for M. japonicus juveniles,and later suggested that a dietary provision of 1% n-3 HUFAcould be considered as a minimal value for postlarval pe-naeids (Kanazawa et al., 1979e). Shewbart and Mies (1973)showed that optimum growth of Farfantepenaeus aztecuswas achieved by the addition of 1% LNA to the diet. Ingrowth experiments with P. monodon, Chen and Tsai (1986)indicated a requirement for HUFA at 0.5-1% of the diet,while Rees et al. (1994) observed that postlarvae can growwell on an Artemia diet with n-3 HUFA ranging from 12 to22 mg/g dry weight. Merican and Shim (1997) observed thatgrowth and survival responses of juvenile P. monodonimproved with a lower supplementation level of DHA rela-tive to LNA. Interestingly, Glencross and Smith (1999)reported that the magnitude of the growth response of P.monodon was greater with LOA than with LNA, and a simi-lar effect was reported by Read (1981) in F. indicus. Xu et al.(1994) suggested that for F. chinensis the requirement forLNA may be between 0.7% and 1% of the diet, but onceDHA was adequately provided in the diet (around 1%),growth, molt frequency and survival were significantlygreater than in animals fed a diet with 1% LNA. They con-cluded that although n-6 FA like LOA and AA have benefi-cial effects on growth and survival, n-3 FA, especially DHAare the most potent EFA for this species. Lim et al. (1997)evaluated the growth response and FA composition of juve-nile L. vannamei fed different dietary lipids. They found thatmenhaden oil, rich in n-3 HUFA, was better utilized by thisspecies, but among plant oils, those rich in LNA had a high-er nutritional value than those rich in LOA. They concludedthat both n-6 and n-3 FA appear to be essential in the diet,although n-3 HUFA were required for maximum growth,feed efficiency, and survival.

Because there are differences in the feeding habits, i.e.from omnivorous to carnivorous, among penaeid species,and even among developmental stages, generalizations con-cerning requirements for FA should be made cautiously.Kanazawa et al. (1979f) suggested that differences in theeffect of dietary LNA on growth of various shrimp speciesmay be partly explained by differences in the capacity forbioconversion of LNA to HUFA. This capacity is extremelylow in M. japonicus, such that they are incapable of synthe-sizing enough EPA and DHA from dietary LNA to meet theirrequirements.

4. Phospholipids

Phospholipids (PL) are so called polar lipids, becausethey possess at least one polar group. They are chemically

composed of di-acylated glycerol molecules with a phos-phatic moiety attached to the C3 of the glycerol group. Theirfatty acid residues vary in chain length and degree of satura-tion. According to Paltauff and Hermetter (1990), PL can bedivided into sphingophospholipids (e.g., sphingomyelin) andglycerophospholipids, whose structure allows variation inthe nature of the alcohol esterified to the phosphate, leadingto different glycerophospholipid classes (Table 2).

4.1. Role of dietary phospholipids

PL are the major constituents of membranes and arevital to the normal function of every cell and organ. Theymaintain cell structure and function, and have regulatoryactivities within the membrane and outside the cell. Forinstance, they serve as second messengers in cell signaling,an essential process in regulating cell growth, proliferation,differentiation, metabolism, nutrient uptake, ion transport,and even programmed cell death. In addition, there is evi-dence that PL containing choline, sphingomyelin, and theirmetabolites are important mediators and modulators oftransmembrane signaling (Zeisel, 1993).

PL act as emulsifiers and facilitate the digestion andabsorption of FA, bile salts and other lipid-soluble matters.They also have a role in the transport of lipids, not only inthe transport of absorbed lipids from the gut epithelium intothe hemolymph, but also in the transport of lipids betweentissues and organs (Coutteau et al., 1997), given that PL areconstituents of lipoproteins. Phosphatidylcholine (PC) isparticularly important because it is an essential componentof these lipoproteins (Hertrampf, 1992). High densitylipoproteins (HDL) and very high density lipoproteins(VHDL) are the main lipoproteins found in some crustaceanspecies (Lee and Puppione, 1978). PL also act as acyl donorsfor the lecithin cholesterol acyltransferase (LCAT) to convertcholesterol into cholesterol ester, but crustacean hemolymphis likely to have a lower LCAT activity than mammalianblood, since cholesterol esters are found only in traceamounts (Mankura et al., 1980; Teshima, 1997).

Dietary PL may serve as a source of choline, inositol,EFA or even energy, and for early stages of crustaceans it hasbeen suggested that PL present in the diet serve as a directsource of these nutrients (Coutteau et al., 1997). Emphasishas been given to the beneficial effect of PL for early stagesor juvenile shrimp because, even though some crustaceanscan synthesize PL (Shieh, 1969), their biosynthesis general-ly cannot meet their metabolic demand (DAbramo et al.,1981; Kanazawa et al., 1985).

4.2. Phospholipid composition

The effect of PL on growth and survival of crustaceansseems to vary with the FA and the kind of compounds ester-ified at the C-3 position with phosphoric acid. Apparently,effective PL for M. japonicus need to possess choline andinositol groups besides unsaturated FA, such as LOA, LNA,

EPA, and DHA. According to Kanazawa et al. (1985), PCand phosphatidylinositol (PI) containing high levels of n-6and n-3 FA probably serve as the lipid moieties of HDL in M.japonicus. DAbramo et al. (1982) suggested that crus-taceans may also prefer dietary PL to triglycerides as asource of EFA, and may even be precursors in the synthesisof diglycerides and triglycerides (DAbramo et al., 1980).

4.3. Phospholipid requirements in shrimp

To date, several studies have demonstrated the benefi-cial effect of supplementing PL to the diet of shrimp, such asM. japonicus (Kanazawa et al., 1979g; Teshima et al., 1982;Kanazawa et al., 1985; Teshima et al., 1986a, b; Camara etal., 1997), F. chinensis (Kanazawa, 1993), P. monodon(Piedad-Pascual, 1986), and L. vannamei (Coutteau et al.,1996; Gong et al., 2000). In a study with M. japonicus,Kanazawa et al. (1985) observed a possible interactionbetween dietary soybean PC and n-3 HUFA. Growth andsurvival rates increased with increasing levels of soybeanPC, and with increasing n-3 HUFA levels from 0% to 1%,and decreased at 2% HUFA level when diets contained 3%soybean PC; however, Kontara et al. (1997) failed to detectany significant interaction between dietary soybean PC andn-3 HUFA. Coutteau et al. (1996) reported that the growthresponse of early postlarval L. vannamei was significantlyimproved by addition of 1.5% soybean PC to the diet. Withincreasing dietary level of soybean PC, higher proportions of20:1n-9, EPA, and total n-6 PUFA were observed in total FAof shrimp tissue. Fatty acid composition of PC in shrimp tis-sue was very much influenced by dietary levels of soybeanPC; increasing its level decreased the proportion of saturat-ed FA while LOA and EPA increased.

4.4. Sources of phospholipids

All products of plant and animal origin contain PL, butnot all contain high levels. Products of plant origin which arerich sources of PL are soybeans, sunflower seeds, rape seeds,maize, and groundnuts. Excellent animal sources of PL areegg yolk, brain, and eye tissues (Hertrampf, 1992).Generally, fish eggs contain a large amount of PL. In Atlanticherring (Clupea harengus), PL represent almost 70% of thetotal lipids in the ripe eggs (Tocher et al., 1985), from whichPC accounts for 58%. Moreover, PL from neural tissues likebrain and eyes are rich sources of EFA. For instance, DHA isnormally found in higher concentrations in polar lipids(Henderson and Tocher, 1987). Today soybean oil is themain source of natural PL. Microorganisms such as bacteria,algae, fungi, and yeast have been considered as prospectivesources of PL (Hertrampf, 1992).

5. Conclusions

Through experimental research we have learned that n-3 HUFA are presumably required to achieve maximum

growth, feed efficiency, and survival of shrimp. However,quantitative requirements for EFA by many species currentlycultured throughout the world have not been completelydefined. When studying dietary requirements for EFA,emphasis should be made in the need for investigating inter-actions among EFA, e.g., competitive interactions betweenthe n-3 and n-6 series of FA for -6 desaturase, or betweenFA for a given elongase. Because of these competitive inter-actions among and between FA, the need for investigatingappropriate dietary ratios of FA arises, because feeding inad-equate proportions of particular FA to shrimp may result inbiochemical imbalances and less fit animals. Another inter-action that should be addressed is that between EFA andother nutrients such as PL. Research using known PLsources, e.g., purified PL of a particular class and knowncomposition of FA, will help understand their metabolic role,and their importance in contributing to EFA of an organism.A possible effect of total dietary lipid content on require-ments of shrimp for EFA, or the consideration of an optimallevel of neutral (e.g., triglycerides) and polar (e.g., PL) lipidsin shrimp diets also should be addressed in further investiga-tions. Those investigations can be pursued while searchingfor alternative lipid sources to exploit in the aquacultureindustry.

References

Burr, G.O., Burr, M.M., 1929. A new deficiency disease pro-duced by the rigid exclusion of fat from the diet. J. Biol.Chem. 82, 345 pp.

Camara, M. R., Coutteau, P., Sorgeloos, P., 1997. Dietaryphosphatidylcholine requirements in larval and postlar-val Penaeus japonicus Bate. Aquacult. Nutr. 3, 39-47.

Catacutan, M.R., 1991. Growth and fatty acid compositionof Penaeus monodon juveniles fed various lipids. Isr. J.Aquacult. Bamidgeh. 43, 47-56.

Chen, H.Y., Tsai, R.H., 1986. The dietary effectiveness ofArtemia nauplii and microencapsulated food for postlar-val Penaeus monodon. In: Chuang, J.L., Shiau, S.Y.(Eds.), Research and development of aquatic animalfeed in Taiwan, Vol. I. F.S.T. Monograph series No. 5,Fisheries Society of Taiwan, Taipei, pp. 73-79.

Clandinin, M.T., Jumpsen, J., 1997. Fatty acid metabolism inbrain in relation to development, membrane structure andsignaling. In: Yehuda, S., Mostofsky, D.I. (Eds.),Handbook of Essential Fatty Acid Biology: Biochemistry,Physiology, and Behavioural Neurobiology. HumanaPress, Totowa, New Jersey, pp. 15-65.

Coutteau, P., Camara, M. R., Sorgeloos, P., 1996. The effectof different levels and sources of dietary phosphatidyl-choline on the growth, survival, stress resistance, andfatty acid composition of postlarval Penaeus vannamei.Aquaculture 147, 261-273.

Coutteau, P., Geurden, I., Camara, M.R., Bergot, P., Sorgeloos,P., 1997. Review on the dietary effects of phospholipid infish and crustacean larviculture. Aquaculture 155, 149-164.

DAbramo, L.R., Bordner, C.E., Dagget, G.R., Conklin,D.E., Baum, N.A., 1980. Relationships among dietarylipids, tissue lipids, and growth in juvenile lobsters.Proc. World Maricult. Soc. 11, 335-345.

DAbramo, L.R., Bordner, C.E., Conklin, D.E., 1981.Essentiality of dietary phosphatidylcholine for the sur-vival of juvenile lobsters. J. Nutr. 111, 425-431.

DAbramo, L.R., Bordner, C.E., Conklin, D.E., 1982.Relationship between dietary phosphatidylcholine andserum cholesterol in the lobster Homarus sp. Mar. Biol.67, 231-235.

Freeman, E.J., Terrian, D.M., Dorman, R.V., 1990.Presynaptic facilitation of glutamate release fromisolated hippocampal mossy fiber nerve endings byarachidonic acid. Neurochem. Res. 15, 743-750.

Glencross, B.D., Smith, D.M., 1999. The dietary linoleic andlinolenic fatty acids requirements of the prawn Penaeusmonodon. Aquacult. Nutr. 5, 53-63.

Gong, H., Lawrence, A.L., Jiang, D.-H., Gatlin, D.M. III,2000. Lipid nutrition of juvenile Litopenaeus vannamei:I. Dietary cholesterol and de-oiled soy lecithin require-ments and their intersaction. Aquaculture 190, 307-326.

Henderson, R.J., Tocher, D.R., 1987. The lipid compositionand biochemistry of freshwater fish. Prog. Lipid. Res.26, 281-347.

Hertrampf, W. J., 1992. Feeding aquatic animals with phos-pholipids II. Fishes. Lucas Meyer Publication No. 11.Lucas Meyer GmbH & Co., Hamburg. 70 pp.

Holman, R.T. 1966. General introduction to polyunsaturatedacids. Prog. Chem. Fats Other Lipids 9, 3-12.

Kanazawa, A., 1993. Essential phospholipids of fish andcrustaceans. In: Kaushik, S.J., Luquet, P. (Eds.), FishNutrition in Practice, 24-27 June, Biarritz, France. LesColloques nr. 61, INRA, Paris, pp. 519-530.

Kanazawa, A., Tokiwa, S., Kayama, M., Hirata, M., 1977.Essential fatty acids in the diet of prawn: I. Effects oflinoleic and linolenic acids on growth. Bull. Jpn. Soc.Sci. Fish. 43, 1111-1114.

Kanazawa, A., Teshima, S., Endo, M., Kayama, M., 1978.Effects of the eicosapenenoic acid on growth and fattyacid composition of the prawn, Penaeus japonicus.Mem. Fac. Fish. Kagoshima Univ. 27, 35-40.

Kanazawa, A., Teshima, S., Ono, K., Chalayondeja, K.,1979a. Biosynthesis of fatty acids from acetate in theprawns, Penaeus monodon and Penaeus merguiensis.Mem. Fac. Fish., Kagoshima Univ. 28, 21-26.

Kanazawa, A., Teshima, S., Tokiwa, S., Ceccaldi, H.J.,1979b. Effects of dietary linoleic and linolenic acids ongrowth of prawn. Oceanol. Acta 2, 41-47.

Kanazawa, A., Teshima, S., Tokiwa, S., Kayama, M., Hirata,M., 1979c. Essential fatty acids in the diet of prawn: II.Effect of docosahexaenoic acid on growth. Bull. Jpn.Soc. Sci. Fish. 45, 1141-1153.

Kanazawa, A., Teshima, S., Endo, M., 1979d. Requirementsof prawn, Penaeus japonicus for essential fatty acids.Mem. Fac. Fish. Kagoshima Univ. 28, 27-33.

Kanazawa, A., Teshima, S., Tokiwa, S., 1979e. Biosynthesis offatty acids from palmitic acid in the prawn, Penaeus japoni-cus. Mem. Fac. Fish. Kagoshima Univ. 28, 17-20.

Kanazawa, A., Teshima, S., Ono, K., 1979f. Relationshipbetween essential fatty acid requirements of aquatic animalsand the capacity for bioconversion of linolenic acid to high-ly unsaturated fatty acids. Comp. Biochem. Physiol. 63B,295-298.

Kanazawa, A., Teshima, S., Tokiwa, S., Endo, M., Abdel Razek,F.A., 1979g. Effects of short-necked clam phospholipids onthe growth of prawn. Bull. Jpn. Soc. Sci. Fish. 45, 961-965.

Kanazawa, A., Teshima, S., Sakamoto, M., 1985. Effects ofdietary lipids, fatty acids, and phospholipids on growth andsurvival of prawn (Penaeus japonicus) larvae. Aquaculture50, 39-49.

Kates, M. 1972. Techniques of lipidology: isolation, analysis andidentification of lipids. Vol. 3 part II of the series LaboratoryTechniques in Biochemistry and Molecular Biology. North-Holland Pub. Co., Amsterdam, pp. 229-610.

Kayama, M., Hirata, M., Kanazawa, A., Tokiwa, S., Saito, M.,1980. Essential fatty acids in the diet of prawn-III. Lipidmetabolism and fatty acid composition. Bull. Jpn. Soc. Sci.Fish. 46, 483-488.

Klenk, E., Mohrhauer, H., 1960. Metabolism of polyene fattyacids in the rat. Z. Physiol. Chem. 320, 218-232.

Kontara, E.K.M., Coutteau, P., Sorgeloos, P., 1997. Effect ofdietary phohospholipid on requirements for and incorpora-tion of n-3 highly unsaturated fatty acids in postlarvalPenaeus japonicus Bate. Aquaculture 158, 305-320.

Lee, R.F., Puppione, D.L., 1978. Serum lipoproteins in the spinylobster, Panulirus interruptus. Comp. Biochem. Physiol.59B, 239-243.

Leger, Ph., Bieber, G.F., Sorgeloos, P., 1985. International studyon Artemia: XXXIII. Promising results in larval rearing ofPenaeus stylirostris using a prepared diet as algal substituteand for Artemia enrichment. J. World Aquacult. Soc. 16,354-367.

Lim, C., Ako, H., Brown, C.L., Hahn, K., 1997. Growth responseand fatty acid composition of juvenile Penaeus vannamei feddifferent sources of dietary lipid. Aquaculture 151, 143-153.

Mankura, M., Dalimunthe, D., Kayama, M., 1980. Comparativebiochemical studies on plasma cholesterol-II. Bull. Jpn. Soc.Sci. Fish. 46, 583-586.

Mayes, P., 1993. Lipids of physiologic significance. In: HarpesBiochemistry, 23rd Ed., Appleton and Lange, Norwalk, CT,pp. 134-145.

Mead, J.F., Alfin-Slater, R.B., Howton, D.R., Popjk, G., 1986.Lipids: Chemistry, Biochemistry and Nutrition. PlenumPress, New York, 486 pp.

Merican, Z.O., Shim, K.F., 1997. Quantitative requirements oflinoleic and dosahexaenoic acid for juvenile Penaeus mon-odon. Aquaculture 157, 277-295.

Padley, F.B., Gunstone, F.D., Harwood, J.L., 1994. Occurrenceand characteristics of oils and fats. In: Gunstone, F.D.,Harwood, J.L., Padley, F.D. (Eds.), The Lipid Handbook.Chapman & Hall, London, pp. 47-224.

Paltauf, F. and Hermetter, A., 1990. Phospholipids- Natural, semi-synthetic, synthetic. In: Hanin, I. and Pepeu, G.Phospholipids. Plenum Press, New York, pp. 1-12.

Piedad-Pascual, F., 1986. Effect of supplemental lecithin andlipid sources on the growth and survival of Penaeus mon-odon juveniles. In: Asia Fisheries Society. Proceedings ofthe First Asian Fisheries Forum. Manila, Philippines, pp.615-618.

Read, G.H.L., 1981. The response of Penaeus indicus(Crustacea:Penaeidea) to purified and compounded diets ofvarying fatty acid composition. Aquaculture 24, 245-256.

Rees, J.F., Cur, K., Piyatiratitivorakul, S., Sorgeloos, P.,Menasveta, P., 1994. Highly unsaturated fatty acid require-ments of Penaeus monodon postlarvae: an experimentalapproach based on Artemia enrichment. Aquaculture 122,193-207.

Schwartz, R.D., Yu, X., Wagner, J., Ehrmann, M., Mileson, B.E.,1992. Cellular regulation of the benzodiazepine/GABAreceptor: arachidonic acid, calcium and cerebral ischemid.Neurophysiopharmacology 6, 119-125.

Schweitzer, P., Madamba, S., Siggins, G.R., 1990. Arachidonicacid metabolites and mediators of somatostatin-inducedincrease of neuronal M-current. Nature 346, 464.

Shewbart, K.L., Mies, W.L., 1973. Studies on nutritional require-ments of brown shrimpthe effect of linolenic acid ongrowth of Penaeus aztecus. Proc. World Maricult. Soc. 4,227-287.

Shieh, H.S., 1969. The biosynthesis of phospholipids in the lob-ster, Homarus americanus. Comparative culture of penaeidshrimp. Biochem. Physiol. 30, 679-684.

Tacon, G. J., 1987. The nutrition and feeding of farmed fish andshrimpa training manual 1. The Essential Nutrients. FAO,field doc. 2, 21-28.

Templeton, W.W., 1988. Prostanoid actions on transmitterrelease. In: Curtis-Prior (Ed.), Prostaglandins: Biology andChemistry of Prostaglandins and Related Eicosanoids.Churchill-Livingstone, Edinburgh, UK, pp. 402-410.

Teshima, S., 1997. Phospholipids and Sterols. In: DAbramo,L.R., Conklin, D.E., Akiyama, D.M., (Eds.), CrustaceanNutrition: Advances in World Aquaculture, Vol. 6. TheWorld Aquaculture Society, Baton Rouge, Louisiana, pp. 85-107.

Teshima, S., Kanazawa, A., Sasada, H., Kawasaki, M., 1982.Requirements of larval prawn, Penaeus japonicus, for cho-lesterol and soybean phospholipids. Mem. Fac. Fish.Kagoshima Univ. 31, 193-199.

Teshima, S., Kanazawa, A., Kakuta, Y., 1986a. Effects of dietaryphospholipids on growth and body composition of the juve-nile prawn. Bull. Jpn. Soc. Sci. Fish. 52, 155-158.

Teshima, S., Kanazawa, A., Kakuta, Y., 1986b. Effects of dietaryphospholipids on lipid transport in the juvenile prawn. Bull.Jpn. Soc. Sci. Fish. 52, 159-163.

Tocher ,D. R., Fraser, A. J., Sargent, J. R., Gamble, J. C., 1985.Lipid class composition during embryonic and early larvaldevelopment in Atlantic herring (Clupea harengus). Lipids20, 84-89.

Willis, A.L., 1987. Handbook of Eicosanoids: Prostaglandins andRelated Lipids. Vol. I. Chemical and Biochemical Aspects.Part A. CRC Press, Boca Raton, Florida, 314 pp.

Xu, X., Wenjuan, J., Castell, J.D., ODor, R., 1993. The nutri-tional value of dietary n-3 and n-6 fatty acids for the Chineseprawn (Penaeus chinensis). Aquaculture 118, 277-285.

Xu, X., Wenjuan, J., Castell, J.D., ODor, R., 1994. Essentialfatty acid requirement of the Chinese prawn, Penaeuschinensis. Aquaculture 127, 29-40.

Yehuda, S., Rabinovitz, S., Mostofsky, D.I., 1997. In: Yehuda, S.,Mostofsky, D.I. (Eds.), Handbook of Essential Fatty AcidBiology: Biochemistry, Physiology, and BehavioralNeurobiology. Humana Press, Totowa, New Jersey, pp. 427-452.

Zeisel, S. H., 1993. Choline deficiency. J. Nutr. Biochem. 1, 332-344.

Common name # of C Family Shorthand nomenclature Systematic name Structural formula

Linoleic acid 18 n-6 18:2n-6 Cis, cis-9, 12- CH3(CH2)4[CH=CH-octadienoic acid CH2]2 -(CH2)6COOH

-Linolenic acid 18 n-3 18:3n-3 all cis-9, 12, 15- CH3CH2[CH=CH-octadecatrienoic acid CH2]3-(CH2)6COOH

Arachidonic acid 20 n-6 20:4n-6 all cis-5, 8, 11,14- CH3(CH2)4[CH=CH-eicosatetraenoic acid CH2]4 -(CH2)2COOH

Eicosapentaenoic acid 20 n-3 20:5n-3 all cis-5, 8,11,14, 17- CH3CH2[CH=CH-eicosapentaenoic acid CH2]5-(CH2)2COOH

Docosahexaenoic acid 22 n-3 22:6n-3 all cis-4,7,10,13,6,19- CH3CH2[CH=CH-docosahexaenoic acid CH2]6-CH2COOH

Table 1. Some polyunsaturated and highly unsaturated fatty acids.

R-group Class Systematic name Abbreviation

-H Phosphatidic acid or 1,2-diacyl-sn-glycerol-3- PAPhosphoric acid phosphoric acid

-CH2-CH2-N(CH3)3 Phosphatidylcholine 1,2-diacyl-sn-glycerol-3- PCphosphorylcholine

-CH2-CH(NH2)COOH Phosphatidylserine 1,2-diacyl-sn-glycerol-3- PSphosphorylserine

-CH2-CH2-NH2 Phosphatidylethanolamine 1,2-diacyl-sn-glycerol-3- PEphosphorylethanolamine

Phosphatidylinositol 1,2-diacyl-sn-glycerol-3- PIphosphorylinositol

Table 2. Principal glycerophospholipid classes: R-group chemical structure

For additional copies of Aquatunities Technical Bulletins, contact Priscilla Shirley at 717-677-6181 or priscillas@zeiglerfeed.com

OHOH

OHOH

OH