Plasma fatty acid composition in wild and captive nile crocodile, crocodylus niloticus

ANALYSIS OF FATTY ACID PROFILES FOR EASTERN BOX (TERRAPENE CAROLINA CAROLINA) AND COMMON SNAPPING (CHELYDRA SERPENTINE) TURTLES IN WILD AND MANAGED CARE ENVIRONMENTS

The housing of wild animals in managed care facilities requires attention to all aspects of husbandry. Diets of wild animals often differ in composition, consistency, and quantity when compared with those in managed care settings including zoos, rehabilitation facilities, and aquaria. It was hypothesized that dietary differences from wild versus managed care would be reflected in data of circulating fatty acids based on previous studies. The current study examined the effect of species and environment on fatty acid concentrations in two omnivorous species of chelonians: Eastern box turtles, Terrapene carolina carolina, and common snapping turtles, Chelydra serpentina, located in the wild and managed care. Whole blood was collected and placed on spot cards for analysis of 26 fatty acids in a total lipid fatty acid profile. The present research indicated that Eastern box turtles have significantly (P < 0.05) higher percentages of linoleic acid (18:2n6), eicosadienoic acid (20:2n6), and mead acid (20:3n9). Common snapping turtles have significantly (P < 0.05) higher percentages of myristic acid (14:0), dihomo-γ-linolenic acid (20:3n6), erucic acid (22:1n9), and n-6 docosapentaenoic acid (22:5n6). Environmental effects also were noted; wild turtles had higher percentages of α-linolenic acid (18:3n3), arachidic acid (20:0), eicosadienoic acid (20:2n6), and eicosatrienoic acid (20:3n3) (P < 0.05), whereas n-6 docosapentaenoic acid (22:5n6) was higher for the managed care group. Eicosadienoic acid (20:2n6), behenic acid; 22:0), adrenic acid (22:4n6), n-6 docosapentaenoic acid (22:5n6), and nervonic acid (24:1) were significantly different (P < 0.05) in species-environment interactions without any noted species or environment patterns. Fatty acids are useful for many important biological functions including proper immune system regulation, and therefore, the present research provides medically relevant data for reptile diagnostics. This research may help further improve diets of all chelonians kept in managed care, regardless of species.

Variation in plasma lipids during the reproductive cycle of male and female desert tortoises, Gopherus agassizii

Plasma triacylglycerol, phospholipid, cholesterol, cholesterol esters, fatty acids, and total lipids were measured in 30 female and 20 male desert tortoises (Gopherus agassizii) during the annual reproductive cycle in the eastern Mojave desert, Nevada. Blood samples were collected at monthly intervals from April to October. All lipid fractions, with the exception of free fatty acids, were significantly higher in female plasma than in male plasma in all months of the year. In contrast, free fatty acids were higher in male plasma than in female plasma in all months. The seasonal pattern in estradiol secretion mirrored that of triacylglycerol, phospholipid, cholesterol, and total lipid, all of which showed a significant correlation with the hormone. Estradiol and the vitellogenesis-associated lipids were all significantly higher in August, September, October, and April than in June. The seasonal variation in cholesterol ester levels in females did not correlate with any of the reproductive events and did not appear to be involved in yolk precursor formation. Total lipid in males showed a negative correlation with testosterone and spermatogenesis. Individual fatty acids in the June and August samples (at the highest and lowest estradiol levels) were compared in male and female plasma. The percent of C18:3n3, C18:2n6, C18:1n9, C20:5n3, and C22:5 were significantly higher in the June female plasma sample than in the August sample. Docosahexanoic (C22:6n3) acid was barely detectable in female plasma in either month.

Lipid peroxidation and antioxidative enzyme activities in childhood epilepsy

This study aimed to investigate the relationship among lipid peroxidation, subsequent activation of scavenger enzymes (superoxide dismutase and glutathione peroxidase), and the presence of structural abnormality in 52 epileptic children receiving monotherapy (medically responsive) or polytherapy (medically intractable). Plasma lipid peroxidation in epileptic patients with abnormal magnetic resonance imaging (MRI) findings significantly increased as compared with that of 16 healthy children (P < .05), whereas antioxidant enzymes were not significantly affected. Both medically controlled and intractable children with normal MRI had higher activities of superoxide dismutase than those of controls (P < .05). The activity of superoxide dismutase in epileptic patients with structural abnormality did not significantly change as compared with controls. Activity of glutathione peroxidase in all of the epileptic children was not significantly different from controls. The activity of antioxidant enzymes or plasma malonyldialdehyde levels did not correlate with duration of epilepsy, frequency of seizures (> one seizure per month or not), and the presence or localization (focal, multifocal, or generalized) of electroencephalographic or MRI abnormalities. Increased plasma lipid peroxidation may be causally related to the presence of structural abnormality rather than ongoing epileptic activity or therapy status.

Lizards, lipids, and dietary links to animal function

Our experiments were designed to test the hypotheses that dietary lipids can affect whole-animal physiological processes in a manner concordant with changes in the fluidity of cell membranes. We measured (1) the lipid composition of five tissues, (2) body temperatures selected in a thermal gradient (T(sel)), (3) the body temperature at which the righting reflex was lost (critical thermal minimal [CTMin]), and (4) resting metabolic rate (RMR) at three body temperatures in desert iguanas (Dipsosaurus dorsalis) fed diets enriched with either saturated or unsaturated fatty acids. The composition of lipids in tissues of the lizards generally reflected the lipids in their diets, but the particular classes and ratios of fatty acids varied among sampled organs, indicating the conservative nature of some tissues (e.g., brain) relative to others (e.g., depot fat). Lizards fed the diet enriched with saturated fatty acids selected warmer nighttime body temperatures than did lizards fed a diet enriched with unsaturated fatty acids. This difference is concordant with the hypothesis that the composition of dietary fats influences membrane fluidity and that ectotherms may compensate for such changes in fluidity by selecting different body temperatures. The CTMin of the two treatment groups was indistinguishable. This may reflect the conservatism of some tissues (e.g., brain) irrespective of diet treatment. The RMR of the saturated treatment group nearly doubled between 30 degrees and 40 degrees C. Here, some discrete membrane domains in the lizards fed the saturated diet may have been in a more-ordered phase at 30 degrees C and then transformed to a less-ordered phase at 40 degrees C. In contrast, the RMR of the unsaturated treatment group exhibited temperature independence in metabolic rate from 30 degrees to 40 degrees C. Perhaps the unsaturated diet resulted in membranes that developed a higher degree of disorder (i.e., a certain phase) at a lower temperature than were membranes of lizards fed the saturated diet. Our study demonstrates links between dietary fats and whole-animal physiology; however, the mechanistic basis of these links, and the general knowledge of lipid metabolism in squamate reptiles, remain poorly understood and warrant further study.

Hyperlipidemia and reproductive failure in captive-reared alligators: vitamin E, vitamin A, plasma lipids, fatty acids, and steroid hormones

Blood samples were collected from 26 captive-reared alligators (25 females; one male) and 12 (seven females and five males) wild "nuisance" alligators collected by wildlife personnel in south Louisiana in May 1995. The captive alligators, hatched from artificially incubated eggs in 1972-1973, had received vitamin E supplements during the 3 weeks before the blood sample was collected. Each sample was analyzed for vitamin E (alpha-tocopherol), vitamin A (retinol), total lipid, triacylglycerol, phospholipid, cholesterol, cholesteryl ester, free fatty acids, steroid hormones and a standard clinical blood panel. The fatty acid composition of the plasma lipid fraction was also analyzed. Results indicated that 18 of the captive females and three of the seven wild females were undergoing vitellogenesis, i.e. had elevated plasma estradiol and elevated plasma calcium. Vitellogenic females had higher vitamin E than non-vitellogenic females (77.4 microg/ml vs. 28.6 microg/ml in captive females; 24.0 microg/ml vs. 21 microg/ml in wild females). Plasma retinol was similar in all groups, ranging from 0.5 to 1.4 microg/ml and close to values reported in birds. All lipid fractions, with the exception of cholesteryl ester, were higher in captive alligators than in wild alligators. There were also significant differences in the fatty acid composition of wild and captive alligators. Plasma eicosapentaenoic and docasahexaenoic acid were higher in wild than in captive alligators, whereas linoleic was higher in captive than in wild.