Developmental changes in the fatty acids of rat uterus and the influence of dietary essential fatty acids.

The effect of age on uterine fatty acid composition was studied in rats fed diets of differing fatty acid composition. Uteri of newly weaned 23-day rats had a higher fatty acid content and a higher proportion of short-chain (less than or equal to C18) fatty acids. Higher incorporation of C less than or equal to 18 fatty acids into neutral lipid (NL) and phospholipid (PL) of young 42-day rats compared with adult 240-day rats was detected. Uterine NL incorporated predominantly C less than or equal to 18 fatty acids which may be an important metabolic energy store in developing uterine tissue. Incorporation of C less than or equal to 18 fatty acids by uterine PL and NL was relatively unselective. In contrast, there was selective retention of arachidonic acid (AA) and docosahexanoic acid (DHA) throughout uterine development. An effect of dietary EFA on uterine n-3 and n-6 EFA was detected in each age group. There was marked retention of uterine AA when dietary supplies of n-6 EFA were low, but the total AA, eicosapentaenoic acid (EPA) and DHA in uterine PL remained constant in the three diet groups, and a constant content of AA, EPA and DHA was maintained throughout uterine development, regardless of diet. The degree of n-3 substitution achieved in this study inhibited uterine release of PG and parturition in adult rats.     

Effects of selenium deficiency on fatty acid metabolism in rats fed fish oil-enriched diets.

The hepatic fatty acid metabolism was investigated in rats stressed by selenium deficiency and enhanced fish oil intake. Changes in the composition of lipids, peroxides, and fatty acids were studied in the liver of rats fed either a Sedeficient (8 microg Se/kg) or a Se-adequate (300 microg Se/kg) diet, both rich in n-3 fatty acid-containing fish oil (100 g/kg diet) and vitamin E (146 mg alpha-tocopherol/kg diet). The two diets were identical except for their Se content. Se deficiency led to a decrease in hair coat density and quality as well as to changes in liver lipids, individual lipid fractions and phospholipid fatty acid composition of the liver. The low Se status did reduce total and reduced glutathione in the liver but did not affect the hepatic malondialdehyde level. In liver phospholipids (PL), Se deficiency significantly reduced levels of palmitic acid [16:0], fatty acids of the n-3 series such as DHA [22:6 n-3], and other long-chain polyunsaturates C-20-C-22, but increased n-6 fatty acids such as linoleic acid (LA) [18:2 n-6]. Thus, the conversion of LA to arachidonic acid was reduced and the ratio of n-6/n-3 fatty acids was increased. As in liver PL, an increase in the n-6/n-3 ratio was also observed in the mucosal total fatty acids of the small intestine. These results suggest that in rats with adequate vitamin E and enhanced fish oil intake, Se deficiency affects the lipid concentration and fatty acid composition in the liver. The changes may be related to the decreased levels of selenoenzymes with antioxidative functions. Possible effects of Se on absorption, storage and desaturation of fatty acids were also discussed.     

The influence of dietary essential fatty acids on uterine C20 and C22 fatty acid composition.

The effect of dietary fatty acids on uterine fatty acid composition was studied in rats fed control diet or semi-synthetic diet supplemented with 1.5 microliter/g/day evening primrose oil (EPO) or fish oil (FO). Diet-related changes in uterine lipid were detected within 21 days. Changes of 2- to 20-fold were detected in the uterine n-6 and n-3 essential fatty acids (EFA) and in certain saturated and monounsaturated fatty acids. The FO diet was associated with higher uterine C20 and C22 n-3, and the EPO diet, with higher uterine n-6 fatty acid. High uterine C18:2 n-6 was detected in neutral lipid (NL) of rats fed high concentrations of this fatty acid, but there was little evidence of selective incorporation or retention of C18:2 n-6 by uterine NL. The incorporation of EFA into uterine phospholipids (PL) was greater than NL EFA incorporation, and uterine PL n-3/n-6 ratios showed greater diet dependence. Tissue/diet fatty acid ratios in NL and PL also indicated preferential incorporation/synthesis of C16:1 n-9, and C16:0, and there was greater incorporation of C12:0 and C14:0 into uteri of rats fed EPO and FO. Replacement of 50-60% of arachidonate with n-3 EFA in uterine PL may inhibit n-6 EFA metabolism necessary for uterine function at parturition.     

Lipid and fatty acid content in wild white seabream (Diplodus sargus) broodstock at different stages of the reproductive cycle

The lipid and fatty acid content of the gonads, liver and muscle of wild white seabream males and females was studied at different stages of the reproductive cycle. Samples were taken from mature white seabream at pre-spawning (November), mid-spawning (March) and post-spawning (June) stages. The results showed that lipid accumulates in gonads and muscle from November to March. The gonadosomatic index (GSI) was also increased during this period. Male gonads showed a greater increase in polar lipid (PL) than neutral (NL), while female gonads displayed the reverse. The increase in both neutral and polar lipid was higher in the muscle of males than in females. In the same period, male livers showed no changes either in lipid content or the hepatosomatic index (HSI), while female livers registered an increase in both lipid content and HSI. Between March and June, in both males and females, total, neutral and polar lipid decreased sharply in the gonads and muscle. Muscular lipid content reduction was more pronounced in males than females. On the other hand, the lipid content of the liver in males and females remained relatively constant. In general terms, the amounts of major fatty acids (16:0, 18:1n-9, 20:5n-3 and 22:6n-3) in gonadal and muscular polar and neutral lipid in both males and females increased from November to March and declined thereafter. Variations of the liver fatty acid content were less extreme. In the period from mid-spawning to post-spawning, the presence of 20:4n-6 in polar and neutral lipid increased to a notable extent in all organs studied.     

Seasonal dynamics of fatty acid composition in female northern pike (Esox lucius L.)

Seasonal changes in the fatty acid composition of neutral and polar lipids were measured in the ovary, liver, white muscle, and adipopancreatic tissue of northern pike. The role of environmental and physiological factors underlying these changes was evaluated. From late summer (August–September) to winter (January–March), the weight percentage of n-3 polyunsaturated fatty acids (especially 22:6n3) declined significantly in the neutral lipids of all somatic tissues examined. However, large quantities of n-3 polyunsaturated fatty acids accumulated in the recrude cing ovaries during fall and the weight percentage of n-3 polyunsaturated fatty acids in ovary polar lipids also increased significantly. Additionally, the n-3 polyunsaturated fatty acid content of somatic polar lipids increased significantly during fall due to increases in the total polar lipid content of the somatic tissues. This suggests that during fall n-3 polyunsaturated fatty acid are diverted away from somatic neutral lipids and thereby conserved for use in ovary construction and for incorporation into tissue polar lipids. The percentage of n-3 polyunsaturated fatty acid in ovary neutral lipids also declined during fall and early winter, perhaps as an adaptation to conserve these fatty acids for storage in oocyte polar lipids and later incorporation into cellular membranes of the developing embryo. Reductions in the n-3 polyunsaturated fatty acids content of somatic and ovarian neutral lipids during fall were compensated for specifically by increases in the percentage of monounsaturated fatty acids rather than saturated fatty acids. This suggests that the ratio of saturated to unsaturated fatty acids in pike neutral lipid, is regulated physiologically, and hence may influence the physiological functioning of these lipids. During fall and early winter the percentage of saturated fatty acids declined significantly in the polar lipids of all tissues examined. This change was consistent with the known effects of cold acclimation on the fatty acid composition of cellular membranes. As the ovaries were recrudescing from September to January, liver polar lipids exhibited significant decreases in the percentage of total polyunsaturated fatty acids and n-3 polyunsaturated fatty acids and increases in monounsaturated fatty acids, and acquired a fatty acid composition very similar to that of ovary polar lipids. Therefore, seasonal changes in the percentage of polyunsaturated and monounsaturated fatty acids in liver polar lipids probably reflect the liver's role in vitellogenesis rather than the effects of temperature on membrane fatty acid composition. At all times of year, the fatty acid compositions of white muscle and adipopancreatic tissue neutral lipids were very similar, which may indicate a close metabolic relationship between these lipid compartments.Abbreviations AP adipopancreatic - BHT butylated hydroxytoluene - CI confidence interval - EFA essential fatty acids - MUFA monounsaturated fatty acids - NL neutral lipids - PL polar lipids - PUFA polyunsaturated fatty acids - SFA saturated fatty acids     

Effects of crude rapeseed oil on lipid composition in Arctic charr Salvelinus alpinus

This study investigated the effects of crude rapeseed oil (RO) on lipid content and composition in muscle and liver of Arctic charr Salvelinus alpinus . Triplicate groups were fed diets containing fish oil (FO):RO ratio of 100:0, 75:25, 50:50 and 25:75 until two-fold mass increase. Total lipid content increased significantly in the liver with higher proportion of RO in the diet. Profound effects were seen in the fatty acid composition in the analysed tissues with a reduction in 20:5n-3 and 22:6n-3 and an increase in 18:2n-6 with higher RO content in the diets. A drop in cholesterol content was seen at 25% inclusion of RO in both tissues. Wild-caught fish contained a considerably higher amount of 20:4n-6 in both storage and membrane lipids of white muscle compared with the experimental fish.     

Reproduction response of Chinese mitten-handed crab (Eriocheir sinensis) fed different sources of dietary lipid

The effect of feeding three semi-purified diets containing different lipid sources (anchovy oil, soybean oil and pork lard) on fecundity, hatchability and egg fatty acid composition of Chinese mitten-handed crab (Eriocheir sinensis) broodstock was compared with a fresh clam diet in a 6-month feeding trial. Broodstock crabs fed the diet containing pork lard showed poor fecundity and low hatchability. Crabs fed the diet containing soybean oil showed improved fecundity; however, no significant improvement in hatchability was observed. Broodstock fed the diet containing anchovy oil showed the highest fecundity and egg hatchability. Eggs from broodstock fed anchovy oil as sole dietary lipid had a higher n-3 polyunsaturated fatty acid (PUFA) content (33.3%) compared with those of crabs fed diets with soybean oil (20.1%) and pork lard (16.3%) as lipid sources. The results indicate a close correlation between: (1) the 20:5n-3 content of the egg lipid and fecundity; (2) the 22:6n-3 content and hatchability; and (3) fecundity, hatchability and n-3/n-6 fatty acid ratio. The results also suggest that each of these n-3 HUFAs may play different and specific roles in crab reproduction and that either must be adequate in the broodstock diet.     

Lipid and fatty acid composition of muscle and liver from wild and captive mature female broodstocks of white seabream, Diplodus sargus

Total lipids (TL), lipid classes, and their associated fatty acids from muscle and liver of captive and wild mature female broodstocks were investigated in order to estimate the fatty acid requirements of white seabream (Diplodus sargus). The results showed that the percentage of triacylglycerol was higher in liver and muscle of captive fish than in wild fish. The distribution of phospholipid classes in liver and muscle of both fish groups was similar, phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol being the predominant lipid classes. The general pattern of fatty acid distribution in total lipid of liver and muscle from captive and wild fish was similar. However, the relative percentage of specific fatty acids differed in captive and wild fish. The most noteworthy difference was the lower proportion of arachidonic acid (20:4n-6, AA) and the higher proportion of eicosapentaenoic acid (20:5n-3, EPA) in liver and muscle of captive fish with respect to those of wild fish. The proportion of docosahexaenoic acid (22:6n-3, DHA) did not differ between the two fish groups. The differences in EPA and AA proportions between captive and wild fish implied that captive fish presented a higher EPA/AA ratio and a lower DHA/EPA ratio than wild fish. In general terms, in both liver and muscle, the differences in fatty acid composition observed for TL were extended to all lipid classes. The results suggest that the different AA, EPA and DHA proportions in liver and muscle between captive and wild broodstocks are attributed to different levels of these fatty acids in broodstock diets.     

Inverse modifications of heart and liver alpha-tocopherol status by various dietary n-6/n-3 polyunsaturated fatty acid ratios

The effect of dietary n-6/n-3 fatty acid ratio on alpha-tocopherol homeostasis was investigated in rats. Animals were fed diets containing fat (17% w/w) in which the n-6/n-3 ratio varied from 50 to 0.8. This was achieved by combining corn oil, fish oil, and lard. The polyunsaturated to saturated ratio and total alpha-tocopherol remained constant in all diets. Results showed that enrichment of n-3 polyunsaturated fatty acids in the diet, even at a low amount (3.9% w/w), resulted in a dramatic reduction of blood alpha-tocopherol concentration, which, in fact, is the result of a decrease in plasma lipids, since the alpha-tocopherol to total lipids ratio was not significantly altered. The most striking effect observed was a considerable alpha-tocopherol enrichment (x 4) of the heart as its membranes became enriched with n-3 polyunsaturated fatty acids. This process appeared even with a low amount of fish oil (3.9% w/w) added to the diet. Accordingly, a strong positive correlation was found between heart alpha-tocopherol and docosahexaenoic acid (r = 0.86) or docosahexaenoic acid plus eicosapentaenoic acid levels (r = 0.84). Conversely, the liver alpha-tocopherol level dropped dramatically when n-3 polyunsaturated fatty acids were gradually added to the diet. It is concluded that fish oil intake dramatically alters the alpha-tocopherol homeostasis in rats.     

Preferential accumulation of fatty acids in the testis and ovary of cultured and wild sweet smelt Plecoglossus altivelis

The effect of dietary lipid on the fatty acid composition of muscle, testis and ovary of cultured sweet smelt, Plecoglossus altivelis, was investigated and compared with that of wild sweet smelt. Cultured fish were fed three different diets for 12 weeks: a control diet rich in docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) (CO group); a diet deficient in DHA and EPA (DP group); and a diet rich in alpha-linolenic acid (ALA, 18:3n-3), but deficient in DHA and EPA (LP group). The fatty acid composition of muscle and gonad lipids was related with dietary fatty acids. Despite the difference in DHA and EPA content in the diets, muscles and gonads, respectively, contained almost equal levels of DHA and EPA in each CO and DP group. However, the muscle and gonad of the LP group showed a lower level of DHA than other groups, due to having the highest level of ALA. In the wild fish muscle, the DHA content was similar to that of CO and DP groups, but the EPA content showed the highest level in all groups. There was no difference in the muscle fatty acid proportions between male and female. On the other hand, the testes of cultured and wild fish were rich in DHA, EPA, docosapentaenoic acid and arachidonic acid, while ovaries were rich in oleic, palmitoleic, linoleic acids and ALA. Moreover, of all the groups, the fish fatty acid composition of the LP group was closest to that of wild fish. These results indicate that in the sweet smelt, tissue n-3 polyunsaturated fatty acids (PUFAs) greater than C20 can be synthesized from dietary precursors and special fatty acids are preferentially accumulated to the testis or ovary, respectively, to play different physiological functions.     

Effect of n-3 and n-6 fatty acids on hepatic microsomal lipid metabolism: a time course study

The present study examines the time dependent effects of n-6 and n-3 polyunsaturated fatty acids on liver microsomal lipid metabolism in FVB mice fed a diet supplemented with a mixture of free fatty acids (mainly 18:3n-6 and 20:5n-3) at 25 mg/g diet. Significant changes in the fatty acid composition of total liver and microsomal lipids were observed after 7 days on the diets. Thereafter, some animals remained on the same diet while others were fed a diet supplemented with hydrogenated coconut oil (HCO). With the exception of 20:5n-3 which showed a slower recovery, establishment of the HCO pattern was rapid indicating that the diet-induced changes could be easily reversed. The unsaturation index, the cholesterol/phospholipid ratio and the microviscosity of the microsomal membranes were not affected by these dietary manipulations. Unsaturated fatty acid supplementation reduced the activity of ⁹ desaturase by 50%. Feeding the HCO diet to mice previously fed the EPA/GLA diet led to a progressive increase in ⁹ desaturase activity, reaching 80% of the day zero values after 14 days. The monoene content of hepatic total lipids reflected, in most cases, the changes in enzyme activity. This study shows that a low dose of a n-3 and n-6 free fatty acid mixture increases the quantities of members of the n-3 family, without loss of n-6 fatty acids in microsomal membranes and modifies the activity of ⁹ desaturase without altering the microsome physicochemical parameters.     

Rapid modulation of the n-3 docosahexaenoic acid levels in the brain and retina of the newly hatched chick

The newly hatched chick obtains its fatty acids almost completely from the lipids of the egg yolk as these are transferred to the developing embryo during its 21-day period of incubation. Since the diet of the laying hen greatly influences the fatty acid composition of the egg lipids, and presumably also the fatty acid composition of the resulting chick, we tested how quickly and to what extent varying the amount of n-3 fatty acids in the diet of the hen would modulate the level of n-3 fatty acids in the brain and retina of the newly hatched chick. White Leghorn hens were fed commercial or semi-purified diets supplemented with 10% fish oil, linseed oil, soy oil, or safflower oil. Eggs, together with the brain, retina, and serum of newly hatched chicks, were then analyzed for fatty acid composition. The fatty acids of egg yolk responded quickly to the hen's diet with most of the change occurring by 4 weeks. There was a linear relationship between the linolenic acid content of the diets and levels of this fatty acid in egg yolk and chick serum. In chicks from hens fed the fish oil diet, the total n-3 fatty acids, including 22:6(n-3), were elevated twofold in the brain and retina and sevenfold in serum relative to commercial diet controls. The safflower oil diet led to a very low n-3 fatty acid content in egg yolks and only 25% of the control n-3 fatty acid content in the brain and retina of chicks.(ABSTRACT TRUNCATED AT 250 WORDS)     

Liver and muscle fatty acid composition of mature and immature rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>) fed two different diets

Fatty acid composition of liver and muscle tissues of immature and mature Oncorhynchus mykiss fed on two different diets were determined. Fatty acid analyses were carried out by gas chromatography. Palmitic acid (C16:0), oleic acid (C18:1 n-9), linoleic acid (C18:2 n-6) and docosahexaenoic acid (C22:6 n-3) were the major components in both liver and muscle tissues of immature and mature rainbow trout of both sexes. The amounts of C22:6 n-3 were higher in the liver (29.04 ± 0.06 − 27.41 ± 0.17%) and muscle (13.05 ± 0.40 − 11.37 ± 0.21%) of immature fish than in mature fish and depended on the composition of the diet. Results of this study show that fatty acid composition in fish tissues can considerably vary, depending on the age of fish and their diet. Thus more detailed studies are necessary on the influence of diet on immature and mature fish fatty acid composition. The age and diet of fish consumed may also be important for human health.     

Modulatory effect of temperature on the influence of dietary linolenic (18 : 3 n-3) and linoleic (18 : 2 n-6) acids on the gonadal recrudescence in Clarias batrachus (L.)

During the late postspawning phase, freshwater catfish Clarias batrachus fed a diet rich in linseed oil (18: 3 n-3) (LSO) and 13L : 11D photoperiod and at 28° C showed increases in ovarian weight and plasma levels of testosterone and oestradiol-17β, and in concentrations of free fatty acids (FFA), monoglycerides (MG), diglycerides (DG), triglycerides (TG), phospholipids (PL) and esterified cholesterol (CE) in the liver, plasma and ovary. In fish fed a diet rich in sunflower oil (18: 2 n-6) (SFO) under the same conditions, plasma testosterone decreased sharply, concentrations of FFA, DG and TG increased in the liver and plasma and ovarian levels of TG and CE decreased. Neither diet was gonadostimulatory when fed at 18°C.     

Effect of slaughter age and feeding system on the neutral and polar lipid composition of horse meat

This study was undertaken to provide a thorough analysis of the neutral lipid (NL) and polar lipid (PL) fractions of horse meat that included the content and distribution of acyl and alkenyl moieties in foals under different rearing conditions. Two groups of crossbred horses were studied; the first group was selected from suckling foals produced under grazing conditions and slaughtered at 4 months of age (n=8), and the second group was selected from concentrate-finished foals and slaughtered at 12 months of age (n=7). There were significant differences related to the age and feeding practices of foals which affected the intramuscular (IM) fat content and the fatty acid (FA) composition of NL and PL fractions. Samples from suckling foals were leaner and provided the highest content of methylation products from the plasmalogenic lipids, and total and n-3 polyunsaturated fatty acid (PUFA). By contrast, the meat from concentrate-finished foals had a higher IM fat level resulting in a greater accumulation of 16:0 and total monounsaturated FAs in the NL fraction, whereas the muscle PL fraction retained a similar FA composition between both groups. Linolenic acid was preferentially deposited in the NL fraction, but linoleic acid and the long-chain n-3 and n-6 PUFAs were incorporated into the PL fraction where they served as cell membrane constituents and in eicosanoid formation.     

Lipid classes and fatty acid composition of rotifers (Brachionus plicatilis) fed two algal diets

Rotifers (Brachionus plicatilis), maintained on baker's yeast, were fed for 24h upon two algal diets, Isochrysis galbana (diet A) and Isochrysis galbana + Nannochloropsis gaditana (diet B). (These algal diets were selected for their potential use as essential fatty acid (EFA) boosters, taking into account the requirements of fish larvae). The effect of these algal diets on total lipid content, lipid classes and fatty acid composition was studied. The total lipid content increased after feeding upon both diets but no significant differences were found between the two types. Neutral lipid and polar lipid contents increased and a positive correlation was observed between the neutral lipids content of rotifers and that of the food supplied. However, the content of polar lipids in rotifers did not depend upon that of the diet. The increase in neutral lipid content was found to be higher in rotifers fed upon diet B, compared to diet A which increased the phospholipid content. Non-enriched rotifers contained only small amounts of polyenoic fatty acids, i.e. 18:3n-6, 18:3n-3, 20:4n-6, 20:5n-3 and 22:6n-3, the contents of which increased significantly by feeding both diets. The EFA composition (20:4n-6, 20:5n-3 and 22:6n-3) of neutral lipids and phopholipids in rotifers reflected the EFA composition of each diet. Diet B-fed rotifers had the highest content in 20:4n-6 and 20:5n-3, whereas rotifers fed diet A and the highest 22:6n-3 content. The mixed diet I. galbana + N. gaditana enhanced substantially the composition of lipid classes i.e. neutral lipids and of n-3 PUFA of rotifers in comparison with Isochrysis or yeast diets.     

Reduction in plasma cholesterol and increase in biliary cholesterol by a diet rich in n-3 fatty acids in the rat

Cholesterol and lipoprotein metabolism were investigated in a group of rats fed a fish oil-supplemented diet, a rich source of n-3 fatty acids. For comparison purposes, other groups of rats were fed either safflower oil (n-6 fatty acids) or coconut oil (saturated fatty acids). Diets were isocaloric and contained identical amounts of cholesterol. Rats fed fish oils for 2 weeks showed a 35% lower plasma cholesterol level than rats fed safflower oil, who in turn showed a 14% lower plasma cholesterol level than those fed coconut oil. The fall in plasma cholesterol level with fish oils was associated with significant falls in low density and high density lipoprotein cholesterol levels, but with no significant change in the ratio of low density to high density lipoprotein cholesterol. The fatty acid compositions of plasma, hepatic, and biliary lipids showed relative enrichment with n-3 fatty acids, reflecting the composition of the diet. The fish oil diet increased the basal secretion rate of cholesterol into bile, but the bile acid secretion rate remained unchanged. It is suggested that n-3 fatty acids reduce the plasma cholesterol level in rats by increasing the transfer of cholesterol into bile.     

Fatty acid composition and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis, fed different dietary lipid sources

Juvenile soft-shelled turtles (Pelodiscus sinensis) were fed 7 diets containing 8% of lard, soybean oil, olive oil, menhaden fish oil, or mixtures of 1 to 1 ratio of fish oil and lard, soybean oil, olive oil for 10 weeks. Growth and muscle proximate compositions of the turtles were not affected by different dietary treatments (p>0.05). Fatty acid profiles in muscle polar lipids, muscle non-polar lipids, and liver polar lipids reflected the fatty acid composition of dietary lipid source. Turtles fed diets containing fish oil generally contained significantly higher (p<0.05) proportion of highly unsaturated fatty acids (HUFA) in both polar and non-polar lipids of muscle and polar fraction of liver lipids than those fed other oils. Non-polar fraction of liver lipids from all groups of turtles contained less than 1% of HUFA. All turtles contained relatively high proportions of oleic acid in their lipids regardless of the dietary lipid source. Further, lipid peroxidation in both muscle tissue and liver microsomes of turtles fed fish oil as the sole lipid source was greater (p<0.05) than those fed fish oil-free diets. Turtles fed olive oil as the sole lipid source had the lowest lipid peroxidation rate among all dietary groups. The results indicate that dietary n-3 HUFA may not be crucial for optimal growth of soft-shelled turtles although they may be used for metabolic purpose. Further, high level of dietary HUFA not only increases the HUFA content in turtle tissues, but also enhances the susceptibility of these tissues to lipid peroxidation.     

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.     

Reversibility of the changes induced by n-3 fatty acids in mouse plasma, liver and blood cell lipids

The changes induced by dietary n-3 fatty acids (FA) in the lipids and FA of plasma, liver and blood cells, and their reversibility, was studied in mice given a diet containing 9% fish oil (FO) for 2 weeks and then returned to, and kept for another 2 weeks on, the usual standard lab chow diet. In plasma, the concentrations of phospholipids (PL), mostly phosphatidylcholine (PC), triacylglycerols (TG), cholesterol and cholesterol esters (CE) decreased rapidly after starting the FO diet, and remained low from day 3 onwards. This decrease was concomitant with a remarkable reduction in the n-6 FA, especially 18:2n-6, not compensated for by the relative enrichment in n-3 FA induced by FO. In liver, TG and CE decreased and PL slightly increased, all of them showing reduced n-6/n-3 ratios. Sphingomyelin, which lacks polyunsaturated FA other than small amounts of 18:2 and 24:2n-6, showed altered ratios between its very long chain monoenes and saturates. In the washout phase, the most rapid event was an immediate increase in 18:2n-6 and after a few days in 20:4n-6 in plasma and liver, where most of the lipid and FA changes were reversed completely in about 10 days. In the case of blood cells even 2 weeks were insufficient for a reversal to the initial n-6/n-3 ratios. The lipid class responsible for this lack of reversibility was phosphatidylethanolamine, PC having returned to the initial fatty acid composition during the stated period.