Fatty acid composition of liver lipids during development of rat

The fatty acid composition of triglycerides and phospholipids from rat liver was determined throughout the period of growth in the rat. Major changes in the triglyceride fatty acid composition were observed during the period studied. The triglycerides from fetal and newborn rats contained only a small percentage of polyunsaturated acids compared with suckling and weanling rats. During the suckling phase the liver triglycerides were rich in long chain polyunsaturated acids such as 20∶4, 20∶5, 22∶5, and 22∶6; once the pups were weaned, the percentage of these acids in the liver triglycerides fell. In these experiments, 18∶2 and 18∶3 were the only polyunsaturated acids in the maternal diet. However, the stomach contents of the suckling pups contained 18∶2 and 18∶3, as well as the long chain polyunsaturated acids. Radioactive 18∶3 and 22∶6 were fed to suckling pups, and the results suggested that the LCP in the rat liver triglycerides during the suckling period were derived from the long chain polyunsaturated acids in the dam's milk, rather than by synthesis from either 18∶2 or 18∶3 within the pups.     

Changes in fatty acid composition of plasma and oviduct lipids during sexual maturation of Japanese quail

The fatty acid (FA) compositions of plasma and oviduct phospholipids (PL) and triglycerides (TG) were studied throughout the natural sexual development of the Japanese quail. In the oviduct, PL concentration increased rapidly during the period of active oviduct cell proliferation and then remained at a constant level during the phase of cellular hypertrophy. Oviduct and plasma TG concentrations were 2- and 10-fold higher, respectively, in fully developed animals than in immature ones. During natural sexual maturation of the quail, the FA compositions of PL and TG were markedly modified both in plasma and in oviduct. These qualitative changes occurred predominantly during the period of intense cellular proliferation of oviduct cells, and also were observed in immature animals injected with physiological doses of estradiol. In oviduct PL, the proportions of 20∶4n−6 and 22∶4n−6 decreased significantly (from 20 to 10% and 3.5 to 0.7%, respectively) whereas those of 18∶2n−6 increased (from 8.5 to 21%). In contrast, the plasma PL proportions of 20∶4n−6, 22∶4n−6 and 18∶2n−6 were decreased significantly and the percentage of 18∶1n−9 doubled, suggesting that the oviduct is able to utilize certain plasma FA to a greater extent than others. Changes in plasma and oviduct lipid composition occurring in the quail during sexual development may be attributed to estradiol, which stimulates hepatic Δ9 desaturase and inhibits the oviduct Δ6 desaturase. The changes in FA composition observed in oviduct phospholipids are discussed in relation to eicosanoid production and cellular proliferation.     

Variations of fatty acid composition of erythrocyte and plasma lipids in the rat during the first period of life

The changes occurring in the fatty acid composition of the erythrocyte lipids during the first weeks of life were studied in the rat. The major changes consisted of a progressive decrease in oleic acid and a progressive increase in linoleic acid. A lower but significant increase in arachidonic acid was also observed. These changes are not related to variations in erythrocyte age; rather, they appear to be related to the age of the animal. Since somewhat similar changes were observed in the fatty acid composition of the major lipid classes of plasma during the first weeks of life, the possibility that these variations could account for the changes in the fatty acid composition of erythrocyte lipids was considered. Some support to this possibility was found in the results of experiments in which erythrocytes taken from 15-day-old rats were incubated with plasma taken from newborn rats. The changes in the fatty acid composition of erythrocytes and plasma lipids do not appear to be dependent on dietary lipids, since they occur during the suckling period, i.e., before the rats begin to ingest the pelleted diet which presents a fatty acid pattern completely different to that of the dams' milk.     

Changes of fatty acid composition of phospholipids in liver mitochondria and microsomes of the rat during growth

The fatty acid patterns of rat liver mitochondrial and microsomal phospholipids were analyzed from term fetuses, 1 and 4 days old, and adult rats. The main fatty acids of phosphatidylethanolamine and-choline were stearic and palmitic acids, although the patterns differed slightly. The fatty acid composition of corresponding phospholipids in mitochondria and microsomes was similar. The fatty acid pattern of cardiolipin was dominated by linoleic acid. The most consistent feature of the developmental changes in the fatty acid patterns of all phospholipids studied was a decrease in the relative amount of monounsaturated fatty acids. The percentages of saturated fatty acids in phosphatidyl-ethanolamine and-choline increased during neonatal development. It is suggested that the high levels of fetal monounsaturated fatty acids were due to low availability of polyunsaturated fatty acids.     

Mitochondrial membrane fatty acid composition in the marmoset monkey following dietary lipid supplementation

Diets supplemented with high levels of saturated fatty acids derived from sheep kidney (perirenal) fat or unsaturated fatty acids derived from sunflowerseed oil were fed to marmoset monkeys for 22 wk. The effect of such diets on plasma, red blood cell phospholipids, and liver, heart, kidney and brain mitochondrial phospholipid fatty acids was determined. Despite large differences in the level and type of lipid present in the experimental diets, there was little effect on the proportion of saturated to unsaturated fatty acids in the phospholipids of the membranes examined. The diets did, however, alter the proportion of the various classes of polyunsaturated fatty acids in the membrane phospholipids, with the sunflower-seed oil diet elevating and the sheep kidney fat diet reducing the n−6/n−3 unsaturated fatty acid ratio, relative to a low (mixed fat) reference diet. This change occurred in all membranes except brain, in which only a small response to altered dietary lipid intake was observed. Elevation of dietary linoleic acid led to an increase in membrane linoleic acid and a marked decrease in membrane arachidonic acid, such that the membranes from animals fed the sunflowerseed oil diet exhibited the lowest proportion of arachidonic acid. In this latter respect, the response of the marmoset monkey to dietary lipid supplementation differs markedly from the rat. Our inability to alter significantly membrane lipid saturation/unsaturation supports the notion that a homeostatic mechanism is in some way responsible for buffering membranes from the effects of significant changes in the nature of the dietary lipid intake.     

Studies on the fatty acid composition of crayfish lipids

The fatty acid composition of carcass and exoskeleton lipids was determined for the freshwater crayfishOrconectes rusticus. Lipid fractions were isolated by column and thin-layer chromatography. Fatty acid methyl esters and alcohol acetates were then prepared and analyzed by gas-liquid chromatography. Peak identities were established from retention time data for methyl esters, hydrogenated methyl esters, and saturated, monoene, diene, and polyene methyl esters separated as acetoxy-mercuri-methoxy derivatives. Minor component acids were estimated from their relative compositions in these fractions. Presented at the symposium honoring J. B. Brown, AOCS meeting in Chicago, 1964.     

Dietary fat and the fatty acid composition of tissue lipids

Some characteristics of the fatty acid composition of animal tissue lipids are described and the origins of tissue fatty acids are discussed briefly. The effect of dietary fat on composition of tissue lipids is discussed. Types of dietary fatty acids for which experimental work is described include polyunsaturated fatty acids, short-chain fatty acids, fatty acids with chain length greater than C₁₈,trans unsaturated fatty acids, fatty acids with conjugated double bonds, acetylenic fatty acids, branched-chain fatty acids and oxygenated fatty acids. The individuality of fatty acids is discussed in relation to their roles as components of tissue lipids.     

Homeostatic control of membrane fatty acid composition in the rat after dietary lipid treatment

Diets in which both the lipid content and composition (polyunsaturated to saturated fatty acid ratio) were varied were fed to rats for 20 weeks, and the effects on the tissue lipid profiles were determined. The fatty acid profile of the plasma lipids, and the phospholipid fatty acids of the mitochondrial and microsomal fractions of liver, heart, kidney and brain, as well as erythrocyte membranes were determined. Despite large differences in the level and type of lipid present in the experimental diets and in the proportion of saturated fatty acids in the plasma lipids in response to the various diets, there was little effect on the proportion of saturated to unsaturated fatty acids in the phospholipids of the various membranes examined. The major effect of altering the dietary level of polyunsaturated to saturated fatty acids was on the ratio of the ω6/ω3 series of unsaturated fatty acids in the membrane lipids. This change occurred in all tissues except the brain, in which only a small response to altered dietary lipid intake was observed. The ω6/ω3 ratio was elevated upon feeding a diet rich in ω6 polyunsaturated fatty acids, but decreased when a diet rich in saturated fatty acids was fed. The failure to significantly alter membrane lipid saturation/unsaturation in the tissues examined would suggest that a homeostatic mechanism is operative in biological membranes and may act to buffer membranes from the effects of changes in the nature of the dietary lipid intake.     

Altered fatty acid desaturation and microsomal fatty acid composition in the streptozotocin diabetic rat

Streptozotocin diabetes in the rat diminishes the synthesis of both monounsaturated and polyunsaturated fatty acids. Rat liver microsomal fatty acid composition and fatty acid desaturation were studied in the streptozotocin diabetic rat. The major alterations in fatty acid composition found in the diabetic rat were decreased proportions of palmitoleic, oleic and arachidonic acids and an increased proportion of linoleic and docosahexaeneoic acids. These findings, other than the increased docosahexaeneoic acid, probably result from the diminished liver microscomal δ9 and δ6 desaturase activities found in these animals. These changes are not due to the diminished weight gain of the diabetic animals since restricting food intake of control animals to achieve a similar weight gain failed to reproduce either the changes in fatty acid composition or the decrease in fatty acid desaturation. The increased food intake of the diabetic animal may contribute to the altered proportions of linleic and arachidonic acids since limiting food intake in diabetic animals to that of normal controls diminished the magnitude of these changes. Insulin therapy for 2 days not only reverses and overcorrects the diminished desaturase activities, but likewise reverses and overcorrects the altered fatty acid composition, with the exception of the diminished arachidonic aicd levels which are further decreased following insulin therapy. These findings strongly suggest that most of the changes in fatty acid composition in the diabetic rat are indeed caused by the diminished fatty acid desaturase activities.     

Effect of early postnatal dietary sterculate on the fatty acid composition of rat liver and brain lipids

Pregnant rats were fed a high carbohydrate diet containing either 1% trilinolein or 1% trilinolein with 0.2% methyl sterculate from 18 day gestation to 21 day postpartum. The pups were weaned at 21 days and continued on the same diet for an additional 10 days. The microsomal stearyl CoA desaturase activities of the liver were effectively inhibited. Liver triglycerides showed increases in the saturated fatty acids concentrations at the expense of the corresponding monoenes. The concentration ofcis 6–7 octadecenoic acid was elevated. In liver phospholipids, the concentration of stearic acid was increased without a corresponding decrease in the oleic acid content. A drastic decrease in the nervonic acid (24∶1, n−9) concentration of liver sphingomyelin was observed. The lipids of the brain did not contain sterculic acid, and brain desaturase activity was unaffected. There was no significant change in the concentration of monoenoic acids from 16∶1 to 22∶1. However, nervonic acid was decreased by 32%. These results suggest that brain nervonic acid may be derived from a precursor other than oleic acid.     

Effects of lupin oil on carp lipids during chilling 1. Changes in lipid class composition

The effect of lupin (Lupinus termis) oil on the muscle lipids of carp (Cyprinus carpio) during chilling was studied. During chilling, total lipids decreased whereas triglycerides remained almost constant. Neither the behavior of total lipids nor that of triglycerides during chilling was affected by the composition of the dietary lipids. The proportions of ?free”? fatty acids increased and the proportions of phospholipids decreased during chilling. These changes were markedly affected by the composition of the diet.     

Effect of dietary lipids on fatty acid composition of body lipid in rainbow trout (Salmo gairdneri)

Three isocaloric diets were prepared. Diet 1 (Control) contained 22% herring oil. In diets 2 and 3, a third and a half of the herring oil was replaced, respectively, by an animal fat (lard) which contained a high percentage of saturated fatty acids. Each diet was fed to duplicate groups of rainbow trout for 14 wk. The results of the feeding trial indicated that the concentration of the saturated fatty acids in trout body lipid did not increase despite the high concentration of these fatty acids in Diets 2 and 3. Fish growth, feed efficiency, mortality and the level of fatty acid deposited in fish body lipid and phospholipids are discussed. Technical Paper No. 4440, Oregon Agricultural Experiment Station, Oregon State University, Corvallis, OR 97331.     

Lung surfactant and fatty acid composition of lung tissue and lavage of rats fed diets containing different lipids

Two nutritional models, essential fatty acid (EFA) deficiency and the feeding of saturated vs unsaturated fats, were used to determine the effects of dietary lipids on the fatty acid composition of rat lung and lavage. Semipurified diets containing 7% corn oil, 7% hydrogenated coconut oil (EFA-deficient), 10% butter or 10% safflower oil were fed to dams during lactation and thereafter to their offspring for a total of 24 weeks. Lipids were extracted from the lung lavage and lung tissue and their fatty acid composition was determined. The content of dipalmitoylphosphatidylcholine (DPPC), the main surfactant in the lungs, was also determined. The results show that the levels of DPPC in the lungs of rats fed 10% butter decreased although the decrease in the EFA-deficient rats was greater. Comparing rats fed butter with those fed corn oil, there were also modifications in the fatty acid composition of the total lipids and phospholipids of lung tissue and lavage as well as in phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol +phosphatidylserine fractions isolated from the lung tissue. The changes in fatty acid composition were somewhat fewer in rats fed butter then in those fed an EFA-deficient diet. The results suggest that a marginal EFA deficiency produced in rats by long-term feeding of 10% butter may account for the reduction in DPPC levels and in the changes in fatty acid composition in the lung tissue and lavage.     

Tissue phospholipid fatty acid composition in the diabetic rat

Tissue phospholipid fatty acid compositions in streptozotocin-induced diabetic rats were studied. The major changes in liver, plasma, erythrocyte and heart were increased proportions of linoleic and dihomo-γ-linolenic acids and a decreased proportion of aracchidonic acid. The latter was not significantly changed in phospholipids of kidney, adrenal gland and testis. Skin fatty acids in diabetic rats showed an increase in the proportion of arachidonic acid and a reduction in the proportion of linoleic acid. The fatty acid desaturating activity in diabetes may be regulated differently in different tissues.     

Changes in lipid class and fatty acid compositions during maturation ofHibiscus esculentus andHibiscus cannabinus seeds

The major lipid classes and their constituent fatty acids were analyzed in maturing seeds ofHibiscus esculentus andH. cannabinus. The seeds matured in 40 and 45 days, respectively. The active accumulation period was from the 13th to 25th and 15th to 30th day after flowering, respectively. While a continuous increase in the content of triacylglycerols (TAG) was noticed inH. esculentus, TAG was at its peak inH. cannabinus on the 20th day after flowering. The contents of polar lipids were high in the immature seeds but decreased during maturation. The major fatty acids in both species were palmitic, oleic and linoleic. Cyclopropane fatty acids were present only in TAG of both species throughout maturation period. Cyclopropene and epoxy acids appeared in TAG in traces at the final stages of seed maturation. Oleic and linoleic acids were preferentially esterified at the secondary positions of TAG. The contents of palmitic and stearic acids at the secondary positions were sharply reduced as TAG accumulated.     

Effects of ethanol on membrane lipids III. Quantitative changes in lipid and fatty acid composition of nonpolar and polar lipids of mouse total liver,mitochondria and microsomes following ethanol feeding

The effects of ethanol on the total, nonpolar, and polar lipids of whole liver, mitochondria, and microsomes have been evaluated. Differences in the fatty acid composition of various lipid subclasses have been compared in control and ethanol treated mice. On the whole polyunsaturated fatty acids, especially arachidonic (20∶4) and docosahexaenoic (22∶6), were found to decrease. The significance of an enzymatic mechanism vs. a peroxidative mechanism to explain the results is discussed. Decreases also were observed in the ratios of arachidonate/linoleate following ethanol feeding. These changes are thought to be associated with decreases in the activity of the chain elongation-desaturation system. The research described herein was conducted while the authors were associated with the University of Detroit, Detroit, Mich. and represents part of the work submitted by J.N. Miceli in partial fulfillment of the requirements for the Ph.D. degree.     

The fatty acid composition of the lipids from bovine and porcine reproductive tissues

Beef and pork testes, graafian follicles and the residual ovaries were extracted and the lipids from each were separated into lipid classes by thin-layer chromatography. The fatty acids from each class were analyzed as their methyl esters by gas-liquid chromatography. The lipids from the reproductive tissues were found to be relatively rich in polyunsaturated acids, many of which did not correspond to the more commonly encountered unsaturated acids. These less familiar acids were identified by comparing their chromatographic characteristics with standards of established composition. The polyunsaturated acids of lipids of the reproductive tissues examined are predominantly of the linoleate family. Only in the phospholipids of ovarian tissues did the linolenate family of acids reach high proportions of the total polyunsaturates. Nine members of the linoleate family were identified in the lipids of reproductive tissues. Five higher metabolites of oleate were identified as normal components of these tissues. Diglycerides were found as a significant lipid class only in testis tissue. The diglycerides and cholesteryl esters of beef testis contain tetracosatetraenoic acid as major fatty acids. The triglycerides of reproductive tissues are notably rich in polyunsaturated acids. In the study, 16 polyunsaturated acids were identified by ozonolysis-reduction and several others were tentatively identified by retention time data. Two acids, previously unreported, are 10,13,16-docosatrienoic acid and 9,12,15,18-tetracosatetraenoic acid. Presented in part at the First World Fat Congress, Hamburg, October, 1964, and at the meeting of American Oil Chemists’ Society, October, 1964.     

Lipid and fatty acid composition and energy partitioning during embryo development in the shrimp Macrobrachium borellii

Energy partitioning, composition of lipids and fatty acids, and their utilization by embryos were determined in the lecithotrophic shrimp Macrobrachium borellii during seven development stages. The biochemical composition at stage I is represented by lipids, proteins, and carbohydrates, with 29.3, 28.7, and 0.2% dry weight, respectively. The former two were identified as the major energy-providing components, contributing 131 and 60 cal/100 mg egg, dry weight, respectively. The overall conversion efficiency (CE) was 45.0% (calculated as percentage of vitelline energy transformed into embryonic tissues). Lipids were the most important energy reserve (CE 39.3%), followed by proteins (CE 57.1%), both being simultaneously utilized during development while carbohydrates were synthesized de novo (CE 587.5%). Variation in the lipid class composition of embryos and vitellus showed an accumulation of triacylglycerols (TAG) and phospholipids (PL) up to stage IV, a more active accumulation and selective utilization phase (stages V and VI), and a consumption and de novo synthesis period until hatching. Structural lipids (PL and cholesterol) and pigment astaxanthin were selectively conserved in embryos, but TAG, hydrocarbons, and esterified sterols were preferentially depleted. Monounsaturated fatty acids (FA) were the major group in TAG, whereas polyunsaturated FA (PUFA) were the major group in PL after organogenesis. Certain PUFA such as 22∶6n−3 and 20∶5n−3 were selectively accumulated in PL.     

Fatty acid composition of liver lipids in rats fed brominated fatty acids

Feeding rats diets containing brominated corn oil or di- or tetrabromostearate as the monoglyceride produced changes in fatty acid composition of liver lipids. Those changes associated with the feeding of brominated corn oil or tetrabromosterates could be explained by the accumulation of triglyceride, and the changes associated with the feeding of dibromostearate could result from the proliferation of a membrane system. A unique response to the feeding of diets containing brominated corn oil is an increase in the level of γ-linolenic acid.     

Varietal difference in lipid content and fatty acid composition of highbush blueberries

Lipids from five cultivars of highbush blueberries (Vaccinium corymbosum L.) were extracted and fractionated into neutral lipids (60–66%), glycolipids (20–22%) and phospholipids (14–18%). The major fatty acids in all fractions were palmitic (16∶0), oleic (18∶1), linoleic (18∶2), and linolenic (18∶3) acids. All lipid classes had a large concentration of C₁₈ polyunsaturated acids (84–92%), indicating that blueberries are a rich source of linoleic and linolenic acids. Changes in the fatty acid composition of neutral lipids and phospholipids were not significantly different among the five cultivars, but significant differences were noted in the ratios of linoleic and linolenic acids in the glycolipids fraction.