The fatty acid composition of oophagous tadpoles (Chirixalus eiffingeri) fed conspecific or chicken egg yolk

We compared the lipid content and fatty acid composition of (1) the egg yolk of three anuran species (Chirixalus eiffingeri, Rhacophorus moltrechti and Buergeria robustus) and chicken eggs; and (2) C. eiffingeri tadpoles fed conspecific eggs or chicken egg yolk. Anuran and chicken egg yolk contained more non-polar than polar lipids but the proportions varied among species. Chicken egg yolk contained low amounts of 22:5n-3 in the polar lipid fraction, and B. robustus eggs did not contain any n-3 or n-6 non-polar lipids. The specific variation of lipid contents and fatty acid composition may relate to the maternal diet and/or breeding biology. In C. eiffingeri tadpoles that fed chicken yolk or frog egg yolk, the dominant components of polar and non-polar lipids were 16:0, 18:0, 18:1, and 18:2n-6, or 20:4n-6 fatty acids. C. eiffingeri eggs contained more n-3 fatty acids (e.g. 18:3n-3 and 20:5n-3) than chicken egg yolk, and tadpoles fed conspecific eggs contained more of these fatty acids than tadpoles fed chicken egg yolk. The compositional differences in the fatty acids between C. eiffingeri tadpoles that fed frog egg or chicken egg yolk are the reflection of the variation in the dietary sources. Our results suggest a direct incorporation of fatty acids into the body without or minimal modification, which provide an important insight into the physiological aspects of cannibalism.     

Transfer of n-3 and n-6 polyunsaturated fatty acids from yolk to embryo during development of the king penguin

This study examines the transfer of lipids from the yolk to the embryo of the king penguin, a seabird with a high dietary intake of n-3 fatty acids. The concentrations of total lipid, triacylglycerol (TAG), and phospholipid (PL) in the yolk decreased by ~80% between days 33 and 55 of development, indicating intensive lipid transfer, whereas the concentration of cholesteryl ester (CE) increased threefold, possibly due to recycling. Total lipid concentration in plasma and liver of the embryo increased by twofold from day 40 to hatching due to the accumulation of CE. Yolk lipids contained high amounts of C(20-22) n-3 fatty acids with 22:6(n-3) forming 4 and 10% of the fatty acid mass in TAG and PL, respectively. Both TAG and PL of plasma and liver contained high proportions of 22:6(n-3) ( approximately 15% in plasma and >20% in liver at day 33); liver PL also contained a high proportion of 20:4(n-6) (14%). Thus both 22:6(n-3) and 20:4(n-6), which are, respectively, abundant and deficient in the yolk, undergo biomagnification during transfer to the embryo.     

The relationship between the fatty acid profiles of the yolk and the embryonic tissue lipids: A comparison between the lesser black backed gull (Larus fuscus) and the pheasant (Phasianus colchicus)

Although substantial information is available regarding the fatty acid composition of lipids of the yolk and of the developing tissues of the chicken embryo, there is little knowledge on this topic for other avian species. The aim of the present study was to compare the yolk and embryonic tissue fatty acid profiles for a species selecting its food in the wild (the lesser black backed gull) with one fed on a standard commercial diet (the commercially reared pheasant). The fatty acid compositions of the yolk lipids were determined, and major differences were observed between the two species. In particular, the phospholipid of the gull yolk was enriched in 20:4n-6 and 22:6n-3 (18.8 and 7.1%, respectively, by weight of total fatty acids) in comparison with the pheasant (4.0 and 4.1%, respectively). The fatty acid compositions of the embryonic tissues were determined using eggs incubated in the laboratory. For the liver and heart, the fatty acid composition of the lipids in the two species reflected the initial yolk composition, with the gull tissue lipids generally containing higher proportions of 20:4n-6 and 22:6n-3 than those of the pheasant. In contrast, the fatty acid profiles of the brain phospholipid were essentially identical in the two species, with 20:4n-6 and 22:6n-3 comprising approximately 9 and 17%, respectively, of total fatty acids in both cases.     

Distribution of lipids from the yolk to the tissues during development of the water python (<Emphasis Type="Italic">Liasis fuscus</Emphasis>)

Energy metabolism during embryonic development of snakes differs in several respects from the patterns displayed by other reptiles. There are, however, no previous reports describing the main energy source for development, the yolk lipids, in snake eggs. There is also no information on the distribution of yolk fatty acids to the tissues during snake development. In eggs of the water python (Liasis fuscus), we report that triacylglycerol, phospholipid, cholesteryl ester and free cholesterol, respectively, form 70.3%, 14.1%, 5.7% and 2.1% of the total lipid. The main polyunsaturate of the yolk lipid classes is 18:2n-6. The yolk phospholipid contains 20:4n-6 and 22:6n-3 at 13.0% and 3.6% (w/w), respectively. Approximately 10% and 30% of the initial egg lipids are respectively recovered in the residual yolk and the fat body of the hatchling. A major function of yolk lipid is, therefore, to provision the neonate with large energy reserves. The proportion of 22:6n-3 in brain phospholipid of the hatchling is 11.1% (w/w): this represents only 0.24% of the amount of 22:6n-3 originally present in the egg. This also contrasts with values for free-living avian species where the proportion of DHA in neonatal brain phospholipid is 16–19%. In the liver of the newly hatched python, triacylglycerol, phospholipid and cholesteryl ester, respectively, form 68.2%, 7.7% and 14.3% of total lipid. This contrasts with embryos of birds where cholesteryl ester forms up to 80% of total liver lipid and suggests that the mechanism of lipid transfer in the water python embryo differs in some respects from the avian situation.Abbreviations ARA arachidonic acid - DHA docosahexaenoic acidCommunicated by G. Heldmaier     

Metabolic fate of yolk fatty acids in the developing king penguin embryo

This study examines the metabolic fate of total and individual yolk fatty acids (FA) during the embryonic development of the king penguin, a seabird characterized by prolonged incubation (53 days) and hatching (3 days) periods, and a high n-3/n-6 polyunsaturated FA ratio in the egg. Of the approximately 15 g of total FA initially present in the egg lipid, 87% was transferred to the embryo by the time of hatching, the remaining 13% being present in the internalized yolk sac of the chick. During the whole incubation, 83% of the transferred FA was oxidized for energy, with only 17% incorporated into embryo lipids. Prehatching (days 0-49), the fat stores (triacylglycerol) accounted for 58% of the total FA incorporated into embryo lipid. During hatching (days 49-53), 40% of the FA of the fat stores was mobilized, the mobilization of individual FA being nonselective. At hatch, 53% of the arachidonic acid (20:4n-6) of the initial yolk had been incorporated into embryo lipid compared with only 15% of the total FA and 17-24% of the various n-3 polyunsaturated FA. Similarly, only 32% of the yolk's initial content of 20:4n-6 was oxidized for energy during development compared with 72% of the total FA and 58-66% of the n-3 polyunsaturated FA. The high partitioning of yolk FA toward oxidization and the intense mobilization of fat store FA during hatching most likely reflect the high energy cost of the long incubation and hatching periods of the king penguin. The preferential partitioning of 20:4n-6 into the structural lipid of the embryo in the face of its low content in the yolk may reflect the important roles of this FA in tissue function.     

Establishment of the fatty acid profile of the brain of the king penguin (Aptenodytes patagonicus) at hatch: effects of a yolk that is naturally rich in n-3 polyunsaturates

Because the yolk lipids of the king penguin (Aptenodytes patagonicus) contain the highest concentrations of long-chain n-3 polyunsaturated fatty acids yet reported for an avian species, the consequences for the establishment of the brain's fatty acid profile in the embryo were investigated. To place the results in context, the fatty acid compositions of yolk lipid and brain phospholipid of the king penguin were compared with those from three other species of free-living birds. The proportions of docosahexaenoic acid (22:6n-3; DHA) in the total lipid of the initial yolks for the Canada goose (Branta canadensis), mallard (Anas platyrhynchos), moorhen (Gallinula chloropus), and king penguin were (% w/w of fatty acids) 1.0+/-0.1, 1.9+/-0.2, 3.3+/-0.1, and 5.9+/-0.2, respectively. The respective concentrations of DHA (% w/w of phospholipid fatty acids) in brains of the newly hatched chicks of these same species were 18.5+/-0.2, 19.6+/-0.7, 16.9+/-0.4, and 17.6+/-0.1. Thus, the natural interspecies diversity in yolk fatty acid profiles does not necessarily produce major differences in the DHA content of the developing brain. Only about 1% of the amount of DHA initially present in the yolk was recovered in the brain of the penguin at hatch. There was no preferential uptake of DHA from the yolk during development of the king penguin.     

Lipid and fatty acid compositional differences between eggs of wild and captive-breeding alligators (Alligator mississippiensis): an association with reduced hatchability?

Fertile eggs were obtained from the nests of wild and captive-breeding alligators in Louisiana, USA. Whereas embryo hatchability ofthe wild eggs was 94%, in the captive eggs it was only 500%. Analysis of the lipid and fatty acid compositions of the yolks showed extensive differences between the two sets of eggs. In particular, the lipids of the yolks from the captive eggs displayed considerably lower levels of C20 and C22 polyunsaturated fatty acids and higher levels of C18 polyunsaturates than the wild eggs. More specifically, overall levels of n-6 polyunsaturates were increased at the expense of n-3 acids in the captive eggs. In view of the specific role of C20 and C22 polyunsaturated fatty acids in embryo development, it is proposed that the yolk fatty acid compositional differences and the difference in hatchability are associated.     

Lipid composition and utilization in developing eggs of two tropical marine caridean shrimps (Decapoda: Caridea: Alpheidae, Palaemonidae)

Changes in biomass and lipid biochemistry during egg development were studied in the tropical shrimps, Alpheus saxidomus and Palaemonetes schmitti, from Pacific Costa Rica. Freshly-laid eggs of P. schmitti were substantially smaller than those of A. saxidomus; dry mass decreased during embryogenesis in the former species but remained almost constant in the latter one. Water content of eggs close to hatching were similar among both species (roughly 75%). Newly-produced eggs of the two species contained ≈20% fatty acids per egg dry mass; a comparison with data concerning decapods inhabiting tropical and temperate waters revealed that eggs produced by shrimps inhabiting tropical waters tend to have a higher lipid egg content per dry mass than those from temperate regions. Major lipid classes in the eggs of both species were phospholipids and triacylglycerols which increased and decreased during the incubation period, respectively. The predominant fatty acids of P. schmitti eggs were 16:0, 20:5(n-3) and 22:6(n-3) whereas eggs of A. saxidomus showed high amounts of 16:0, 20:5(n-3) and 16:1(n-7), and remarkably low values of 22:6(n-3) fatty acid. Lipid utilization was more pronounced in P. schmitti; in A. saxidomus, eggs close to hatching still contained 70% of the initially deposited fatty acid content which may indicate an enhanced independence of the newly-hatched larvae on external energy resources. The observed differences may partially be related to different habitat preferences, however, the role of adaptation and phylogeny as determinants of egg lipid biochemistry in caridean shrimps remains to be clarified.     

Carotenoid discrimination by the avian embryo: a lesson from wild birds

The concentrations (μg/g wet yolk) of total carotenoids in eggs of the common moorhen (Gallinula chloropus), American coot (Fulica americana) and lesser black-backed gull (Larus fuscus), collected in the wild, were 47.5, 131.0 and 71.6, respectively. In contrast to data for eggs of the domestic chicken, β-carotene was a significant component in the yolks of these three wild species, forming 25–29% by wt. of the total carotenoids present. The concentration of total carotenoids in the livers of the newly-hatched chicks was 5–10 times higher than in the other tissues and β-carotene was again a major component, forming 37–58% of the hepatic carotenoids. In the newly-hatched gull, the proportions of both lutein and zeaxanthin were very low in the liver but high in the heart and muscle when compared with the yolk. By contrast canthaxanthin, echinenone and β-carotene were very minor constituents of heart and muscle when compared with their proportions in the yolk of the gull. The proportions of lutein and zeaxanthin in the liver of the newly-hatched coot and moorhen were also far lower than in the yolk whereas the liver was relatively enriched with β-cryptoxanthin, β-carotene and (in the moorhen) echinenone. The results indicate that avian embryos discriminate between different carotenoids during their distribution from the yolk to the various tissues.     

Evidence for placental transfer of lipids during gestation in the viviparous lizard, Pseudemoia entrecasteauxii

During gestation in the viviparous lizard Pseudemoia entrecasteauxii, the fetus obtains nutrients from two sources: uptake of yolk components from the retained egg (lecithotrophy) and transfer of nutrients from the maternal circulation via the placenta (placentotrophy). Although net placentotrophy in this species is indicated by the observation that the neonate contains 1.7 times more dry matter than the egg, the placental transfer of lipid has not been previously demonstrated. Lipid analysis was performed on newly ovulated eggs and on neonates. The weight of total lipid per neonate (8.2+/-0.5 mg) is significantly (P=0.049) greater than that in the egg (6.8+/-0.4 mg), indicating that the placenta must contribute some lipid to the fetus. On the assumption that 50% of the lipid delivered to the fetus from either source is oxidized for energy, it is calculated that the placenta accounts for 58.5% of the fetal lipid requirements, with the remaining 41.5% being derived from the egg. The fatty acid compositions of the triacylglycerol and phospholipid recovered in the neonatal tissue differ substantially from those of the egg. In particular, the proportions of 18:2n-6 and 18:3n-3 are far lower in the neonatal lipids compared with the egg lipids. On the other hand, the proportion of 22:6n-3 in the phospholipid of the neonate is six times higher than in the phospholipid of the egg. The absolute amount (mg) of 22:6n-3 recovered in the total lipid of the neonate is 3.8 times greater than the amount initially present in the egg. By comparison, the amount of total fatty acid in neonatal lipid is 1.2 times greater than the amount in the egg. Thus, there is a preferential use of 22:6n-3 for tissue phospholipid synthesis during development. We conclude that there is net transfer of fatty acids across the placenta to the fetus of P. entrecasteauxii and a high degree of selectivity in the use of the various fatty acids for fetal tissue lipid synthesis.     

Biosynthesis of oleic, arachidonic and docosahexaenoic acids from their C18 precursors in the yolk sac membrane of the avian embryo

The yolk sac membrane (YSM) of the chicken embryo is known to express δ-9 and δ-6 desaturase activities, suggesting that biosynthesis of the unsaturated fatty acids 18:1n-9, 20:4n-6 and 22:6n-3 might occur during the transfer of yolk lipids across the YSM. If so, this biosynthesis could help to satisfy the demands of the embryonic tissues for these unsaturates. To assess the ability of the YSM to perform these conversions, pieces of the tissue were incubated in vitro with the precursor fatty acids, ¹⁴C-18:0, ¹⁴C-18:2n-6 or ¹⁴C-18:3n-3, and the recovery of radioactivity in the respective products, 18:1n-9, 20:4n-6 and 22:6n-3, was determined. After 4 h of continuous incubation, radioactivity from these precursors was incorporated primarily into triacylglycerol and phospholipid of the tissue pieces. Only small proportions (0.3–4.7%) of this incorporated radioactivity were, however, recovered as 18:1n-9, 20:4n-6 or 22:6n-3. The majority of the incorporated label was retained in the form of the precursor fatty acids. After a 1-h pulse incubation with the ¹⁴C precursors, followed by a 3-h chase incubation in the absence of exogenous label, the conversion of incorporated radioactivity to the end product unsaturates was again relatively low (0.5–8.1%). Thus, although conversions of the precursors to the end product fatty acids were detectable in this system, the biosynthesis of these unsaturates is apparently a quantitatively minor pathway in the YSM. Nevertheless, since the amount of 18:2n-6 in the yolk lipids far exceeds that of 20:4n-6, the conversion of even a small proportion of the former to the latter fatty acid could significantly increase the supply of 20:4n-6 to the embryonic tissues.     

Lipid and fatty acid composition during embryo and larval development of puye Galaxias maculatus Jenyns, 1842, obtained from estuarine, freshwater and cultured populations

Galaxias maculatus eggs and larvae obtained from broodfish captured either in an estuarine or a freshwater environment, as well as from cultured broodstock were analysed to compare their lipid and fatty acid profiles. Results showed a lower lipid content in embryos and larvae from estuarine populations than those from fresh water, denoting the influence of environmental conditions. The n-3:n-6 ratio was higher in eggs from estuarine and cultured populations, being in the range of marine fishes, whereas for eggs from freshwater fish was lower and typical of freshwater fishes. The polyunsaturated fatty acids (PUFA), particularly docosahexaenoic acid (22:6n-3) and eicosapentaenoic acid (20:5n-3), were higher in eggs and larvae of broodstock coming from culture or estuarine environments than in those from fresh water. Moreover, these fatty acids markedly increased after hatching in larvae coming from estuarine populations, suggesting the effect of the environment on fatty acid profiles to physiologically prepare the larvae to adapt to higher salinity conditions. Linoleic acid (18:2n-6) content was higher in fresh water fish and its reduction during embryo and larval development was accompanied by a significant increase of arachidonic acid (20:4n-6), which was not observed in embryos or larvae from broodstock fish from estuary or aquaculture origin. Both environment and diet of broodstock fish affected lipid and fatty acid composition of G. maculatus embryo and larvae as well as their changes during development.     

Captivity diets alter egg yolk lipids of a bird of prey (the American kestrel) and of a galliforme (the red-legged partridge)

The salient feature of the fatty acid profile of kestrel eggs collected in the wild was the very high proportion of arachidonic acid (15.2%+/-0.7% of fatty acid mass, n=5) in the phospholipid fraction of the yolk. Kestrels in captivity fed on day-old chickens produced eggs that differed from those of the wild birds in a number of compositional features: the proportion of linoleic acid was increased in all the lipid fractions; the proportion of arachidonic acid was increased in yolk phospholipid and cholesteryl ester; the proportion of alpha-linolenic acid was decreased in all lipid classes, and that of docosahexaenoic acid was decreased in phospholipid and cholesteryl ester. Partridge eggs from the wild contained linoleic acid as the main polyunsaturate of all the yolk lipid fractions. Captive partridges maintained on a formulated diet very rich in linoleic acid produced eggs with increased levels of linoleic, arachidonic, and n-6 docosapentaenoic acids in the phospholipid fraction; reduced proportions of alpha-linolenic acid were observed in all lipid classes, and the proportion of docosahexaenoic acid was markedly reduced in the phospholipid fraction. Thus, captive breeding of both the kestrel and the partridge increases the n-6/n-3 polyunsaturate ratio of the yolk lipids.     

Composition, accumulation and utilization of yolk lipids in teleost fish

Lipid reserves in teleost eggs are stored in lipoprotein yolk and, in some species, a discrete oil globule. Lipoprotein yolk lipids are primarily polar lipids, especially phosphatidylcholine and phosphatidylethanolamine (PE), and are rich in (n–3) polyunsaturated fatty acids, especially 22:6(n–3) (docosahexaenoic acid, DHA). Oil consists of neutral lipids and is rich in monounsaturated fatty acids (MUFA). Egg lipids are derived from dietary fatty acid, fatty acid mobilized from reserves and possibly fatty acid synthesized de novo. There is selective incorporation of essential fatty acids, particularly DHA, into yolk lipids and discrimination against incorporation of 22:1(n–11). Lipid is delivered to the oocyte by vitellogenin, which is rich in polar lipids, and likely also by other lipoproteins, especially very low density lipoprotein, which is rich in triacylglycerol (TAG). All classes of lipid may be used as fuel during embryonic and larval development and MUFA are preferred fatty acids for catabolism by embryos. Catabolism of oil globules is frequently delayed until latter stages of development. In some species, DHA derived from hydrolysis of phospholipid may be conserved by transfer to the neutral lipid. Recent work has expanded knowledge of the role of DHA in membrane structure, especially in neural tissue, and molecular species analysis has indicated that PE containing sn-1 oleic acid is a prime contributor to membrane fluidity. The results of this type of study provide an explanation for the selection pressures that influence yolk lipid composition. Future work ought to expand knowledge of specific roles of individual fatty acids in embryos along with knowledge of the ecological physiology of ovarian recrudescence, environmental influences on vitellogenin and yolk lipid composition, and the control of yolk lipid accumulation and utilization.     

The metabolism of neutral and polar lipids in eleuthero-embryos and starving larvae of the African catfish Clarias gariepinw

Lipid class analysis was carried out on developing eggs, eleuthero-embryos (yolk sac larvae) and starving larvae of the freshwater species Clarias gariepinus , using thin layer chromatography. Samples were taken at fixed intervals from a large pool of fertilized eggs obtained through induced reproduction of several parent fish. The total lipid content of fertilized eggs fluctuated around 22% of the dry weight and decreased from 21% at hatching to about 12–5% at yolk absorption. In starving larvae, the amount of total lipid per individual remained relatively constant. Polar lipids [phosphatidylcholine (PC) and phosphatidylethanolamine (PE)] together accounted for 73·6 to 80% of total lipid. PC was by far the most abundant lipid class during the entire experimental period (70–75% of total lipid). PC was catabolized proportionally to total lipid, demonstrating its role as the main energy supplier. All yolk PE was converted to body tissue. The neutral Hpids consisted of triglycerides (TAG), cholesterol and cholesteryl esters (respectively 12·5, 10 and 3% of total lipid in newly fertilized eggs). All TAG were depleted before complete yolk absorption.     

Phospholipid fatty acid composition, vitamin E content and susceptibility to lipid peroxidation of duck spermatozoa

Recent studies on chicken semen have suggested that the lipid and fatty acid composition of spermatozoa may be important determinants of fertility. Phospholipid fatty acid composition, vitamin E content and in vitro susceptibility to lipid peroxidation of duck spermatozoa were investigated using GC-MS and HPLC based methods. The total phospholipid fraction of duck spermatozoa was characterized by high proportions of the n-6 polyunsaturated fatty acids arachidonic (20:4n-6), docosatetraenoic (22:4n-6) and docosapentaenoic (22:5n-6) acids but a substantial proportion of the n-3 fatty acid docosahexaenoic (22:6n-3) acid was also present. Palmitic (16:0) and stearic (18:0) fatty acids were the major saturates in sperm phospholipids. Among the phospholipid classes, phosphatidylserine (PS) had the highest degree of unsaturation due to very high proportions of 22:6n-3, 22:5n-6, 22:4n-6 and 20:4n-6, comprising together more than 75% of total fatty acids in this fraction. Phosphatidylethanolamine (PE) also contained high proportions of these four C(20-22) polyunsaturates, which together formed 60% of total fatty acids in this phospholipid. Spermatozoa and seminal plasma of duck semen were characterized by unexpectedly low content of vitamin E, being more than 4-fold lower than in chicken semen. In duck semen the major proportion of the vitamin E (>70%) was located in the spermatozoa. The very high proportion of 22:6n-3 in PS and PE fractions of duck sperm lipids and the comparatively low levels of vitamin E could predispose semen to lipid peroxidation. Nevertheless the in vitro susceptibilities to Fe2+-stimulated lipid peroxidation of duck and chicken spermatozoa were very similar. The results of the study suggest that increased superoxide dismutase and glutathione peroxidase activity and increased antioxidant activity of seminal plasma may compensate for the low levels of vitamin E to help protect the membranes of duck spermatozoa, which exhibit a high degree of unsaturation from oxidative stress.     

Dynamics of fatty acid composition of total lipids during embryonic development of Atlantic salmon Salmo salar L

Dynamics of fatty acid composition of total lipids was studied for freshwater salmon Salmo salar L. during its embryonic development from blastula (3 hours) up to hatching (108 days) as well as in unfertilized eggs. Stable amount of total and some saturated, monounsaturated and polyunsaturated fatty acids (PUFA) of total lipids was observed during embryonic development. Considerable changes in fatty acid composition were observed at the stage of prelarvae hatching, i.e., significant decrease of (n-6) PUFA (18:2(n-6) and 20:4(n-6)) and (n-3) PUFA and increase of total and some saturated and monounsaturated fatty acids was registered. Change in saturation ratio of membrane lipids justifies the presence of the biochemical mechanism forwarded on regulation of cell membrane enzymes in accordance with the changes of internal physiological processes taking place in the organism and fluctuations of external environmental conditions or the preparation period (as reproduction). Data on peculiarities of transformation and utilization of fatty acids during salmon embryonic development may be used for understanding of their functional role in the developing organism as well as for assessing the quality of the caviar.     

Dynamics of fatty acid composition of total lipids during embryonic development of atlantic salmon <Emphasis Type="Italic">Salmo salar</Emphasis> L.

Dynamics of fatty acid composition of total lipids was studied for freshwater salmon Salmo salar L. during its embryonic development from blastula (3 hours) up to hatching (108 days) as well as in unfertilized eggs. Stable amount of total and some saturated, monounsaturated and polyunsaturated fatty acids (PUFA) of total lipids was observed during embryonic development. Considerable changes in fatty acid composition were observed at the stage of prelarvae hatching, i.e., significant decrease of (n-6) PUFA (18:2(n-6) and 20:4(n-6)) and (n-3) PUFA and increase of total and some saturated and monounsaturated fatty acids was registered. Change in saturation ratio of membrane lipids justifies the presence of the biochemical mechanism forwarded on regulation of cell membrane enzymes in accordance with the changes of internal physiological processes taking place in the organism and fluctuations of external environmental conditions or the preparation period (as reproduction). Data on peculiarities of transformation and utilization of fatty acids during salmon embryonic development may be used for understanding of their functional role in the developing organism as well as for assessing the quality of the caviar.     

Lipid Class and Fatty Acid Composition of the Protozoan Parasite of Oysters, Perkinsus marinus Cultivated in Two Different Media

The meront stage of the oyster protozoan parasite, Perkinsus marinus, cultivated in two media with different fatty acid profiles was analyzed for its fatty acid and lipid class composition. The composition of fatty acids in the prezoosporangium stage of the parasite as well as that of the host oyster were investigated. Although the lipid class composition of meronts was dominated by phospholipids and triacylglycerol, there was no triaclgycerol detected in either culture medium. Despite the difference in fatty acid composition of the two media, the fatty acid composition of meronts in each medium was dominated by 14:0, 16:0, 18:0, 18:1(n-9), 20: (n-9), 18:2(n-6) and 20:4(n-6), a profile that differed from its host. The quantities of total lipids and fatty acids in meronts increased as the number of meronts increased and far exceeded the initial amounts in the media and in the initial cell inoculum. The meronts harvested 25 d post-inoculation, had about 3 to 6 times higher total lipids and 4 to 13 times higher fatty acids than the amounts contained in the media. The fatty acid profiles of both prezoosporangia and oysters resembled each other and consisted primarily of 16:0, 20:4(n-6), 20:5(n-3), 22:2delta7,15, and 22:6(n-3). These results indicate that during meront proliferation, the parasite synthesizes certain fatty acids and lipid classes. For development from meront to prezoosporangium, the parasite may rely on its host for lipid resources.     

The influence of diet on fatty acids in the egg yolk of green sea turtles, Chelonia mydas

Fatty acid concentrations found in the yolk of green sea turtles reflect differences in the diet of the mothers. All of the 12 fatty acids measured in yolk samples were significantly different between eggs produced from the pellet and wild-type diets. However, the relative pattern of yolk fatty acids in the green turtle mirrored those of other reptiles. Yolk samples contained mostly (63–67%) 14:0. 16:0, 16:1n-7 and 18:1n-9. Yolks from captive animals on pellet diet contained an additional 17.64% of the total yolk lipid as 12:0 and 18:2n-6. Wild yolks contained an extra 11.41% of lipid as 18:0 and 18:1n-7. Selection of fatty acids for the yolk should balance the energetic and anabolic needs of the embryo. Eggs are provisioned based on maternal metabolism of available nutrients and subtle differences between natural foods and those available in captivity could affect the viability of future eggs.