DIFFERENCES IN TISSUE-SPECIFIC LIPID-COMPOSITION BETWEEN EMBRYOS OF WILD AND CAPTIVE BREEDING ALLIGATORS (ALLIGATOR-MISSISSIPPIENSIS)

Fertile eggs obtained from alligators reared in captivity typically ex hibit high rates of embryonic mortality. Also, the fatty acid composit ion of the yolk lipid of the captive eggs is markedly different from t hat observed in eggs from wild alligators, possibly as a result of dif ferences in maternal diet in the two situations. The fatty acid compos itions of tissue lipids during the embryonic development of wild and c aptive alligators were compared. The lipids of liver, adipose tissue a nd heart of the two types of embryo displayed fatty acid profiles whic h generally reflected the acyl compositions of the respective yolks. T hus the lipids from these tissues of the captive embryos contained mar kedly higher proportionate levels of linoleic and linolenic acids, low er levels of palmitoleic acid, and, in general, lower levels of docosa hexaenoic acid and other C20 and C22 polyunsaturates, in comparison to the values for the wild embryos. In contrast, the fatty acid composit ion of the brain phosphoglycerides was very similar in the two types o f embryo. Thus, at least in those embryos which had survived during th e developmental period studied, the brain was able to maintain a relat ively constant fatty acid composition, in spite of major differences b etween the wild and captive eggs in the proportions of the various fat ty acids supplied from the yolk. It is suggested that a major cause of embryonic mortality in the captive embryos could be a failure to main tain an adequate level of docosahexaenoic acid in the developing brain .