Acid Composition Of Liver Phospholipids Research Articles

Effects of dietary supplemental fish oil during the peripartum period on blood metabolites and hepatic fatty acid compositions and total triacylglycerol concentrations of multiparous Holstein cows

The objectives were to evaluate the effects of dietary fish oil on plasma metabolite, hepatic fatty acid composition, and total triacylglycerol concentrations. Multiparous Holstein cows (n=42) were completely randomized to 1 of 3 treatments at 3wk prepartum. Treatments were no supplemental lipid or supplemental lipid from either Energy Booster (Milk Specialties Co., Dundee, IL) or fish oil. Treatment diets were fed from −21d relative to expected date of parturition until 10d postpartum. Treatments were fed as a bolus before the a.m. feeding. The dose of lipid fed during the prepartum period was 250g, whereas approximately 0.92% of the previous day's dry matter intake was supplemented postpartum. Blood was collected 3 times weekly for determination of plasma metabolites. Liver biopsies were performed at 21 and 10d before expected date of parturition and 1 and 14d after parturition to determine fatty acid compositions and total triacylglycerol concentrations. Dry matter intake, milk yield, and loss of body weight or body condition score were not affected by supplementing the diet with lipid or by the source of lipid. Supplemental lipid tended to increase plasma glucose and decrease nonesterified fatty acids during the postpartum period. Furthermore, plasma β-hydroxybutyrate was reduced during the postpartum period in the lipid-supplemented treatments. However, source of supplemental lipid had no influence on any blood metabolite. Supplemental fish oil altered the fatty acid composition of liver phospholipids and triacylglycerols, decreasing total saturated fatty acids and increasing total n-3 and long-chain polyunsaturated fatty acids (>20 carbon fatty acids). Despite the altered fatty acid composition, hepatic total triacylglycerol concentrations were unaffected by supplemental fish oil. Furthermore, the improved metabolic profile following lipid supplementation did not decrease hepatic total triacylglycerol concentrations.

Impact of dietary protein on lipid metabolism in hamsters is source-dependent and associated with changes in hepatic gene expression

This study tested the hypothesis that protein source is a factor determining the impact of the diet on lipid metabolism in hamsters. Twenty-eight hamsters of similar body weight were assigned for a period of 8 weeks to one of the following four diets (seven per group) containing either 20 % (w/w) casein (CAS), beef protein (BF), wheat gluten (WG) or soya protein (SOY). The fat composition of the diet was the same (15.5 % w/w) in all groups and provided SFA, MUFA and PUFA representative of the average Canadian diet. After an overnight fast, blood and liver were collected for the measurement of serum lipids, fatty acid composition of liver phospholipids and mRNA levels of selected genes involved in lipid metabolism. WG resulted in lower total cholesterol, HDL-cholesterol and non-HDL-cholesterol but, along with SOY, in higher mRNA levels of cholesterol 7 alpha-hydroxylase and LDL receptor. Furthermore, both WG and SOY resulted in lower 18 : 3n-3, 20 : 4n-6, total n-6 PUFA, 18 : 1n-9 and total MUFA, but higher 22 : 6n-3, total n-3 PUFA, 22 : 6n-3/18 : 3n-3 and 22 : 5n-3/18 : 3n-3 ratios in liver phospholipids, and higher hepatic Delta6-desaturase mRNA levels. These results show that the impact of dietary protein on lipid metabolism is source-dependent and associated with changes in mRNA abundances of key hepatic enzymes and receptors.

Correlation between dietary polyunsaturated fatty acids and plasma homocysteine concentration in vitamin B 6-deficient rats

Vitamin B6 as cofactor of Delta6 desaturase is involved in polyunsaturated fatty acid metabolism; moreover, it is a cofactor of the trans-sulfuration pathway of homocysteine. Some studies report that low concentrations of pyridoxine, by increasing homocysteine levels, are associated with coronary artery disease, and carotid and arterial lesions. The aim of this study was to verify whether different dietary amounts of polyunsaturated fatty acids associated with low content of vitamin B6 could modulate homocysteinemia. Thirty-two rats were divided into two groups, one fed a diet with adequate vitamin B6 content the other a diet containing low amount of the same vitamin. Within each group, rats were divided into two subgroups differing in the polyunsaturated fatty acid content of the diet (63 and 33%, respectively). The vitamin B6-deficient diet induced an increase in homocysteine concentration compared to the vitamin B6-normal diet. This increase was tenfold in the subgroup fed high polyunsaturated fatty acid levels and twofold in the other subgroup. The fatty acid composition of liver phospholipids showed a lower arachidonic acid relative molar content and a lower 20:4/18:2 ratio in vitamin B6-deficient groups compared with B6-normal groups. On the basis of the different biological functions of pyridoxine and considering that some factors closely related to atherosclerosis are vitamin B(6) dependent, adequate pyridoxine availability could be necessary to assure a normal long chain fatty acid metabolism and to reduce the risk linked to hyperhomocysteinemia.

Effect of exercise training on the fatty acid composition of lipid classes in rat liver, skeletal muscle, and adipose tissue

The aim of the present study was to examine the effects of 8 weeks of exercise training on the fatty acid composition of phospholipids (PL) and triacylglycerols (TG) in rat liver, skeletal muscle (gastrocnemius medialis), and adipose tissue (epididymal and subcutaneous fat). For this purpose, the relevant tissues of 11 trained rats were compared to those of 14 untrained ones. Training caused several significant differences of large effect size in the concentrations and percentages of individual fatty acids in the aforementioned lipid classes. The fatty acid composition of liver PL, in terms of both concentrations and percentages, changed with training. The TG content of muscle and subcutaneous adipose tissue decreased significantly with training. In contrast to the liver, where no significant differences in the fatty acid profile of TG were found, muscle underwent more significant differences in TG than PL, and adipose tissue only in TG. Most differences were in the same direction in muscle and adipose tissue TG, suggesting a common underlying mechanism. Estimated fatty acid elongase activity was significantly higher, whereas Delta(9)-desaturase activity was significantly lower in muscle and adipose tissue of the trained rats. In conclusion, exercise training modified the fatty acid composition of liver PL, muscle PL and TG, as well as adipose tissue TG. These findings may aid in delineating the effects of exercise on biological functions such as membrane properties, cell signaling, and gene expression.

Influence of maternal dietary n-3 fatty acids on breast milk and liver lipids of rat dams and offspring–a preliminary study

The impact of triacylglycerol (TAG) structure and level of n-3 fatty acids on the fatty acid profile of total breast milk lipids and total liver phospholipids (PL) of dams and offspring (1, 3 and 13 weeks of age), when administered during development, was examined. Pregnant rats were fed experimental diets from the 8 th day of pregnancy throughout lactation. After weaning and until 13 weeks of age, the offspring were fed the same diet as their dams. The experimental diets contained either a specific structured oil, linseed oil or fish oil. In the specific structured oil, α-linolenic acid (18:3n-3) was predominantly located in the sn-2 position of the TAG and the level of 18:3n-3 was 2 mol% or 10 mol%. In the linseed oil diets the level of 18:3n-3 was 2 mol% or 10 mol% as well. Finally, the fish oil diet contained 18:3n-3 as well as 20:5n-3 and 22:6n-3 adding up to a total of 2 mol% n-3 fatty acids. Samples from three animals in each group were analyzed. The highest level of 22:6n-3 in the breast milk was obtained with diets containing this fatty acid itself. The fatty acid profile of rat dam liver PL was very different from the milk lipids indicating that the maternal dietary fats and the fatty acid synthesis in the mammary gland are the major determinants of the fatty acid profile of breast milk, whereas the liver does not significantly add to this. The 20:4n-6 was decreased in breast milk lipids and liver PL of dams and offspring when 18:3n-3 was increased in the diet. When the diet was based on 10 mol% 18:3n-3 from structured lipid trace levels of 22:6n-3 occurred in breast milk. The 22:6n-3 in liver PL of 1 week old offspring was significantly higher when the diet was based on the specific structured oil (2 mol%) compared to linseed oil. The metabolism of fatty acids may therefore be related to their positions in the dietary TAG. In liver PL of 1 week old offspring 22:6n-3 was highest in the groups, in which the breast milk contained pre-formed 22:6n-3. This demonstrates that the milk fatty acids influence the fatty acid composition of liver PL in young offspring. The results showed, furthermore, that dietary 22:6n-3 is a more effective precursor of tissue 22:6n-3 than an equivalent amount of dietary 18:3n-3.

Dietary fish protein lowers blood pressure and alters tissue polyunsaturated fatty acid composition in spontaneously hypertensive rats

Objectives To investigate the effect of two types of dietary protein on blood pressure, liver fatty acid desaturation and composition, and urine 6-keto-prostaglandin-F (PGF 1α) level, the metabolite of prostacyclin. Methods 5-wk-old spontaneously hypertensive rats were fed 20% casein or purified fish protein. The fat source was 5% ISIO oil, which contains 47.9% (ω-6) and 1.7% (ω-3) total polyunsaturated fatty acids. After 2 mo on the diet, systolic blood pressure was reduced with fish protein compared with casein (189.8 ± 10.5 versus 220.7 ± 8.7). Results Excretion of 6-keto-PGF 1α in urine was negatively correlated with blood pressure. Liver cholesterol and phospholipid concentrations were 1.71- and 1.27-fold lower with fish protein than with casein, respectively. The fish protein diet lowered the 20:4(ω-6) proportion and the ratio of 20:4(ω-6) to 18:2(ω-6) in liver microsomal lipids and phospholipids, which was due to the reduced microsomal Δ6(ω-6) desaturation activity. Dietary protein source did not affect ω-3 fatty acid composition, and this was associated with a similar activation of Δ6(ω-3) desaturation in liver microsomes. Conclusions The present data indicated a significant blood pressure–lowering effect caused by fish protein, rather than by casein, that modified the fatty acid composition of liver phospholipids and liver microsomal total lipids.

The Fatty Acid Composition of Liver Phospholipids of the CowBos taurus Infected with the TrematodeOrientobilharzia turkestanica

The Fatty Acid Composition of Liver Phospholipids of the CowBos taurus Infected with the TrematodeOrientobilharzia turkestanica

The fatty acid composition of liver phospholipids of the cowbos taurus infected with the trematodeOrientobilharzia turkestanica

The fatty acid composition of liver phospholipids of the cowbos taurus infected with the trematodeOrientobilharzia turkestanica

Fatty acyl desaturation in isolated hepatocytes from Atlantic salmon (Salmo salar): Stimulation by dietary borage oil containing γ‐linolenic acid

The effects of different dietary oils on the fatty acid compositions of liver phospholipids and the desaturation and elongation or [1-14C]18:3n-3 and [1-14C]18:2n-6 were investigated in isolated hepatocytes from Atlantic salmon. Atlantic salmon smolts were fed diets containing either a standard fish oil (FO) as a control diet, a 1:1 blend of Southern Hemisphere marine oil and tuna orbital oil (MO/TO), sunflower oil (SO), borage oil (BO), or olive oil (OO) for 12 wk. The SO and BO diets significantly increased the percentages of 18:2n-6, 18:3n-6, 20:2n-6, 20:3n-6, and total n-6 polyunsaturated fatty acids (PUFA) in salmon liver lipids in comparison with the FO diet. The BO diet also increased the percentage of 20:4n-6. Both the SO and BO diets significantly reduced the percentages of all n-3 PUFA in comparison with the FO diet. The OO diet significantly increased the percentages of 18:1n-3, 18:2n-6, total monoenes, and total n-6 PUFA in liver lipids compared to the FO diet, and the percentages of all n-3 PUFA were significantly reduced. With [1-14C]18:3n-3, the recovery of radioactivity in the products of delta 6 desaturation was significantly greater in the hepatocytes from salmon fed SO, BO, and OO in comparison with the FO diet. The BO diet also increased the recovery of radioactivity in the products of delta 5 desaturation. Only the BO diet significantly affected the desaturation of [1-14C]18:2n-6, increasing recovery of radioactivity in both delta 6- and delta 5-desaturation products. In conclusion, dietary BO, enriched in gamma-linolenic acid (18:3n-6), significantly increased the proportions of both 20:3n-6 and 20:4n-6 in salmon liver phospholipids and also significantly increased the desaturation of both 18:2n-6 and 18:3n-3 in salmon hepatocytes. The possible relationships between dietary fatty acid composition, tissue phospholipid fatty acid composition, and desaturation/elongation activities are discussed.

Soybean protein lowers serum cholesterol levels in hamsters: Effect of debittered undigested fraction

the undigested fraction (UDF) of soybean protein exerts a marked hypocholesterolemic effect in relation to soybean protein (SOY) in rats. The present study was conducted to confirm whether UDF was effective in hamsters as in rats in combination with different fat sources, either perilla oil (PER) or safflower oil (SAF). Because the hamster, unlike the rat, disliked the bitter taste of UDF, the effect of debittering UDF also was studied. Cholesterol-enriched (0.2%) diets containing 20% protein and 10% fat were fed to hamsters for 4 wk. UDF was more hypocholesterolemic than soybean protein in hamsters regardless of the dietary fat source. The ratio of high-density lipoprotein to total cholesterol essentially remained unchanged. The debittered UDF, without influencing food intake and thereby weight gain, exerted a significant hypocholesterolemic effect comparable with UDF in relation to SOY accompanying stimulation of fecal neutral and acidic steroid excretion. The fatty acid composition of liver phospholipids was influenced by the type of the dietary protein, and both UDF seemed to interfere characteristically more than SOY with the desaturation systems between linoleic acid and arachidonic acid. Thus, the debittered UDF, similar to UDF, exerted a distinct influence on the various parameters of lipid metabolism in relation to SOY.

Effects of randomization of partially hydrogenated corn oil on fatty acid and cholesterol absorption, and tissue lipid levels in rats.

Randomization of partially hydrogenated corn oil containing approximately 45% of trans octadecenoic acid only slightly, but not significantly, increased the lymphatic fatty acid absorption in rats. No effect of randomization was observed on cholesterol absorption. When rats were fed these fats at the 8.8% level (with 1.2% safflower oil) for three weeks, the concentrations of serum cholesterol, and serum and liver phospholipid were significantly higher in randomized fat than in control fat, which was composed of 9% high-oleic safflower oil and 1% palm oil. Liver cholesterol tended to be higher in randomized fat. In contrast, nonrandomized fat was not hyperlipidemic compared to control fat. Although the fatty acid composition of liver phospholipids suggested a possible interference of trans fatty acid with the metabolism of linoleic acid to arachidonic acid, there was no effect of randomization. In the two hydrogenated fat groups, trans octadecenoic acid was incorporated and distributed similarly in adipose tissue triacylglycerol. These observations indicated that randomization of partially hydrogenated fat is not beneficial to various lipid parameters in rats.

Effects of different dietary fats and proteins on cholesterol metabolism and eicosanoid production in hamsters

The present study was conducted to investigate the interaction of dietary protein, soybean protein (SOY) and casein (CAS); and fat, perilla oil (PER, α-linolenic acid) and safflower oil (SAF, linoleic acid), on cholesterol metabolism, liver fatty acid composition and splenic eicosanoid production in hamsters. Cholesterol-enriched diets (0.2%) containing 20% protein and 10% fat were given for 38 days. Neither hypocholesterolemic nor liver cholesterol-lowering effects of SOY in comparison to CAS were observed in this experiment. However, SOY stimulated fecal steroid excretion, particularly in combination with SAF. The fatty acid composition of liver phospholipids was in general not influenced by the type of dietary protein, but SOY interfered the conversion of 20:5n-3 to 22:6n-3 when fed with PER. Splenic production of leukotriene B4 was not influenced by dietary treatments whereas the production of PGE2 was significantly higher in hamsters fed SAF diets, particularly in combination with SOY. Thus, SOY in comparison to CAS has selective effects on various parameters of lipid metabolism when added in cholesterol-enriched diets.

Dietary Fat Influences the Effect of Zinc Deficiency on Liver Lipids and Fatty Acids in Rats Force-Fed Equal Quantities of Diet

Previous studies showed that zinc deficiency influences the fatty acid composition of rat tissues, but the influence of dietary fat on the effects of zinc deficiency was not considered at that time. The present study was therefore conducted to investigate the effect of zinc deficiency on lipid concentrations in the liver and on fatty acid composition of liver phospholipids in rats fed diets containing coconut oil or fish oil, using a bifactorial experimental design. To ensure an adequate food intake all rats were force-fed. The zinc-deficient rats fed the coconut oil diet developed fatty livers, whereas zinc-deficient animals fed the fish oil diet did not. The zinc-deficient rats in both dietary fat groups had lower levels of linoleic acid, arachidonic acid and total (n-6) fatty acids in the liver phospholipids, especially in the phosphatidylcholine, but greater concentrations of (n-3) fatty acids compared with zinc-adequate controls. We conjecture that zinc deficiency influences incorporation of polyunsaturated fatty acids into phosphatidylcholine. The lower levels of arachidonic acid are replaced in the zinc-deficient animals fed a coconut oil diet by docosapentaenoic and docosahexaenoic acids and in the zinc-deficient animals fed a fish oil diet by eicosapentaenoic acid. The replacement of arachidonic acid by other fatty acids in the phospholipids is likely to have implications for prostaglandin synthesis. The study shows that the type of dietary fat influences the effects of zinc deficiency on fatty acid composition and especially on lipid concentrations in the liver.

Effects of dietary soybean and cod-liver oil levels on growth and body composition of gilthead bream ( Sparus aurata)

Gilthead bream ( Sparus aurata) of 1 g mean weight were fed six purified diets supplemented with 12% lipid composed of different proportions of soybean oil (SBO) and cod-liver cil (CLO). The experiment lasted for 5 months. Fish performance and body composition, as well as the fatty acid composition of liver phospholipids, were studied. Fish performance improved with increasing dietary CLO content, approaching an optimum at about 6% CLO. Higher values for liver fat content and hepatosomatic index were observed for diets containing less than 6% CLO suggesting a deficiency of essential fatty acids in these diets. Liver fatty infiltration with low CLO diets was high although a certain degree of fatty infiltration was apparent in livers of all the dietary treatments. Body composition of fish was also affected by dietary lipid composition. Higher protein and lower fat contents were observed for the fish fed low levels of CLO. The eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content of liver phospholipids was high, approaching a constant value after inclusion of 6% CLO. The levels of 20:4 n − 6 were also found to approach a plateau at this level. Saturated and n − 9 fatty acid content remained almost stable, while the level of 18:2 n − 6 in liver phospholipids reflected the amount of SBO in the diet. It is concluded that, under the conditions employed, the minimum requirement of gilthead bream for EPA and DHA is around 0.9% of the diet.

Transglutaminase activity in mouse liver is unaffected by dietary menhaden oil

In order to determine the effect of dietary fats on hepatic transglutaminase activity, male CD-1 mice were fed diets containing 10 wt% menhaden oil (MO) or 10 wt% corn oil (CO) for 4 weeks. Dietary fatty acids significantly altered the fatty acid composition of liver phospholipids. Arachidonic and linoleic acids were replaced by eicosapentaenoic acid and docosahexaenoic acid in mice consuming the MO diet. PGE 2 synthesis decreased by 32% in the livers from mice consuming MO compared to that observed in CO fed mice. Liver transglutaminase activity was unchanged by MO indicating that n-3 polyunsaturated fatty acids do not affect its synthesis or activity.

Fatty acid composition of muscle, heart and liver lipids in Atlantic salmon, Salmo salar, at extremely low environmental temperature

In February 1988 the seawater temperature in Hvalfjördur, W. Iceland, gradually dropped to its freezing point, −1.8°C. In a group of 2-year-old Atlantic salmon, Salmo salar, reared in seawater cages mortality started at −1.4°C. Three-year-old salmon reared under the same conditions survived at −1.7°C. During netting in this supercooled state, instantaneous freezing took place. The influence of cold acclimatization on fatty acid composition of phospholipids (PL) in muscle, heart and liver of 2-year-old Atlantic salmon was examined. The fatty acid composition of muscle and heart PL was slightly influenced by environmental temperature changes from +6.5°C to −1.4°C and the fatty acid composition of liver PL was not affected. The fatty acid pattern of PL from hearts and livers of 3-year-old salmon reared in seawater cages was studied. The samples were collected at −1.7°C. 18:1 n9 levels in liver PL were significantly higher and 22:6 n3 levels were significantly lower in the 3-year-old salmon than in the 2-year-old salmon. The salmon were fed two types of highly polyunsaturated fatty acid (PUFA)-rich diets (moist or dry pellets). The dry pellets contained significantly higher levels of n3 PUFA (20:5 n3 and 22:6 n3) than the moist pellets. In muscle the fatty acid composition of PL was markedly influenced by the fatty acids profile of the dietary lipids. Salmon fed dry pellets contained significantly lower percentage levels of 18:1 n9 and higher levels of 22:6 n3 in muscle PL than salmon fed moist pellets. The 20:5 n3 level in muscle PL was significantly lower in salmon fed dry pellets than in those fed moist pellets. No influence of dietary lipids was observed on fatty acid composition in heart and liver PL.

Temperature mediated restructuring of phosphatidylethanoloamines in livers of freshwater fishes

1. 1. Fatty acid composition of liver phospholipids of warm and cold adapted freshwater fishes, differing in feeding habit ( Cyprinus carpio, omnivorous; Hypophatalmithryx molitrix, phytoplankton feeder; Aristichtis nobilis, zooplankton feeder: Ctenophyryngodon idella, feeding higher plants and Esox lucius, carnivorous) were investigated. All the fishes accumulated higher amounts of long chain polyunsaturated fatty acids, to the cost of saturated fatty acids, when adapted to cold. 2. 2. Liver slices prelabeled with [1- 14C]palmitic acid at 22°C liberate label in the free fatty acid fraction when exposed to 5°C in the absence of label in the incubation medium. This was not seen when [1- 14C]arachidonic acid was used as a label. Cycloheximide counteracted the cold induced activation of phospholipase A. 3. 3. There is an increase in the level of oleic acid at the cost of stearic acid in position 1 of phosphatidylethanolamines and in some cases of phosphatidylcholines in livers of cold-adapted fish. Marine fish collected from North Atlantic water ( Clupea harengus) showed the same level as those inhabiting tropic seas ( Sardinella longiceps). 4. 4. Liver slices of carp preferred to direct [1- 14C]oleic-, versus [9- 3H]palmitic acid into the position 1 of phosphatidylethanolamines at 5°C. Cycloheximide counteracted the cold induced accumulation of oleci acid in phosphatidylethanolamines. 5. 5. The results are discussed in terms of reorganization of the molecular architecture of phosphatidylethanolamines in cold adapted fish.

The composition of alkanes in exhaled air of rats as a result of lipid peroxidation in vivo Effects of dietary fatty acids, vitamin E and selenium

Alkane production in exhaled air of rats has been studied as an index of lipid peroxidation in vivo in these animals. The effect of feeding essential fatty acid-deficient rats varying levels of n A, n-6 and n-7 polyunsaturated fatty acids for various periods of time has been studied with regard to the composition of the alkanes produced as well as the fatty acid composition of liver phospholipids and liver and adipose tissue triacylglycerols. It was found that the fatty acid composition of liver lipids depended markedly on the nature and the quantity of polyunsaturated fatty acid in the diet. The composition of the alkanes produced on stimulation of lipid peroxidation in vivo by inhalation of small, non-lethal doses of carbon tetrachloride corresponded closely to the fatty acid composition of the liver phospholipids. The results strongly suggest that the alkanes produced as a result of lipid peroxidation in vivo originate from the methyl end of the fatty acid administered. So ethane is produced from n-3 acid, propane from n-4 acid, pentane from n-6 acid and hexane from n-7 acid. The amounts of a specific alkane produced increase as its corresponding fatty acid, as present in the liver phospholipids, increases. There sare indications that relatively more ethane than pentane is produced on stimulation of the in vivo lipid peroxidation although there are considerably more n-6 fatty acids than n-3 fatty acids present in the liver phospholipids.

Effects of Dietary Protein and EFA Deficiency on Liver Δ5, Δ6 and Δ9 Desaturase Activities in the Early Developing Rat

The influence of protein restriction and EFA deficiency during early development in the rat on the activities of delta 5, delta 6 and delta 9 desaturases was studied. The effect of these diets on body weights and in the fatty acid composition of liver phospholipids was also investigated. The results indicate that the body weights of pups were lowered by feeding the dams both the low-protein and the EFA-deficient diet. The activities of delta 5, delta 6 and delta 9 desaturases were reduced in about 60% by protein deficiency but a rise in the activity of delta 9 desaturase of 362.2% was promoted by feeding the dams the low-fat diet. The fatty acid composition of liver phospholipids indicates that partial deprivation of proteins during early development is associated with a decreased ratio of arachidonate to linoleate. Besides the low-fat group shows in the fatty acid composition of liver phospholipids the typical pattern of EFA deficiency, increased 18:1 and 20:3 omega 9 and decreased 18:2 and 20:4. It is evident from the current investigation that partial deprivation of protein during early development may impair the conversion of linoleate to arachidonate in the rat and that the lack of arachidonic acid observed in the liver cells during protein deficiency would be the consequence of this impairment.

Dietary influences on fatty acid metabolism in the liver of the neonatal lamb.

A "protected" polyunsaturated fatty acid supplement was fed to ewes during the last 8 weeks of pregnancy. The effect of this dietary supplement on the essential fatty acid composition of the liver phospholipids and associated changes in the liver delta9- and delta6-desaturase activities were investigated and compared with the effects of directly dosing the newborn lambs for 8 days with an unprotected polyunsaturated oil, maize oil. The maternal dietary supplement produced significant changes in the essential fatty acid composition of the neonatal lamb liver phospholipids. Although the liver delta6-desaturase activity in these animals was also significantly higher than in the lambs from control ewes, the delta9-desaturase was unaffected by maternal dietary supplementation. Direct dosing of the newborn lambs with maize oil failed to produce any signficant changes either in the liver phospholipid fatty acid composition or in the delta9- and delta6-desaturase activities. These results are discussed in terms of the dietary control of liver desaturase enzyme systems.