Lipid Class Distribution Research Articles

Lipid distribution and composition of commercially farmed atlantic salmon (salmosalar)

AbstractSkin, red and white muscle, belly flap, dorsal fat depot, backbone, head, visceral tissue and liver of commercially farmed Atlantic salmon (Salmo salar) were analysed for total lipid content, lipid classes and fatty acid composition. The fat is deposited in a number of tissues and organs with the highest level in the dorsal fat depot (38.4% of wet weight), red muscle (27.2%) and belly flap (28.1%). The fat content in white muscle is 9.6% of wet weight. The lipid class distribution is nearly uniform throughout the fish body. The belly flap contains the highest amount of triacylglycerols (98.8% of total lipid) and white muscle and visceral tissue have the lowest levels, 93.3% and 93.1%, respectively. The variation in total saturates, monoenes, polyenes, n‐6 and n‐3 fatty acids was much less between tissues than the variation in total lipid content. In the edible part, the belly flap (16.7%) contained significantly lower levels of n‐3 fatty acids than red (18.4%) and white muscle (19.7%) mainly due to lower level of 22: 6n‐3 and 20: 5n‐3 fatty acids.

Epicuticular waxes from vascular plants and particles in the lower troposphere: Analysis of lipid classes by Iatroscan thin-layer chromatography with flame ionization detection

The neutral lipids in a variety of samples of acrosol particulate matter, representative source vegetation, and soil have been analyzed by Iatroscan thin-layer chromatography (TLC) with flame ionization detection (FID). Iatroscan, combining the separation capabilities of TLC on silica coated chromarods with semiquantitation by FID, provides a rapid and sensitive method for lipid analysis which is lacking in the other analytical procedures. Lipid classes were analyzed in extracts of a collection of rural atmospheric particles, epicuticular waxes from possible source vegetation, and soil, covering four geographic regions in a transect across the State of Oregon, U.S.A. Aerosol particles, epicuticular waxes of representative vegetation species, and surface soil contain large amounts of unknown polar material, with similar amounts of neutral lipids including hydrocarbons, carboxylic acids, ketones (aldehydes), wax esters (generally not detectable in the aerosols), and alcohols. The distributions of the lipid classes in the epicuticular waxes of the vegetation vary a great deal from species to species. The distribution of the lipid classes in surface soil differs from those of the vegetation and aerosol particles. Comparison of the neutral lipid classes in the predominant vegetation waxes and the aerosols permitted a general correlation between the source vegetation and the corresponding aerosol particles. This is the first description of a rapid single scan method for the separation and analysis of extractable organic matter from aerosol particles and vegetation using the latroscan TLC with FID.

Lipid composition and synthesis of HaCaT cells, an immortalized human keratinocyte line, in comparison with normal human adult keratinocytes.

Cultured keratinocytes are frequently employed for studies of epidermal lipid metabolism. Interpretation of experimental data may be complicated by donor to donor variability, the relatively short culture lifetime and variations between passages, problems that are not encountered to the same extent with immortalized cell lines. The present study was undertaken to compare the lipid composition and synthesis of normal human adult keratinocytes (NHAK) with HaCaT cells, a long-lived, spontaneously immortalized human keratinocyte line, in relation to proliferation and differentiation. No differences between the two cell types were observed: a) in total lipid content; b) in the distribution of major lipid classes during growth at 50%, 75% and 100% confluence; c) in cultures grown at 0.6 mM calcium, at which differentiation is retarded, or at 1.6 mM calcium, at which some differentiation takes place; d) in the incorporation of [14C] acetate into cellular lipids at confluence, or e) in the fatty acid composition of major cellular lipid classes. At 100% confluence NHAK and HaCaT cells differ in their cholesterol metabolism. At all stages of growth, cholesterol synthesis in HaCaT cells is more LDL-dependent than in NHAK. Furthermore, NHAK become less LDL-dependent at confluence whereas HaCaT cells do not. HaCaT cells also revealed a significantly larger fraction of phosphatidyl-ethanolamine, -serine and -inositol at 0.6 mM calcium concentration than NHAK. These findings suggest that HaCaT cells do not differentiate as well as NHAK in vitro and may therefore serve as a model for the study of lipid metabolism in cells defective in terminal differentiation.

Contributing factors in the trafficking of [ 3H]arachidonate between phospholipids

Cultured human promyelocytic leukemia cells (HL-60), depleted of arachidonic acid by continued growth in serum-free media, were used as a model system to examine various factors that control the incorporation and distribution of [ 3H]arachidonic acid into classes and subclasses of cellular lipids. Increasing the culture media concentration of [ 3H]arachidonic acid from 1 × 10 −8 M to 1 × 10 −5 M caused a greater percentage of the cellular tritium to be distributed into triacylglycerols (from <1% at 1 × 10 −8 M to 38% at 1 × 10 −5 M) with a corresponding decrease in cellular [ 3H]diradylglycerophosphoethanolamine (from 53% at 1 × 10 −8 M to 12% at 1 × 10 −5 M) during 2 h incubations. A greater proportion of the tritium present in diradylglycerophosphoethanolamine and diradylglycerophosphocholine, at the higher media concentration of [ 3H]arachidonic acid (1 × 10 −5 M), was found in the diacyl subclasses of these two lipids than was observed at the lower concentrations (<1 × 10 −6 M) of [ 3H]arachidonic acid. Significant amounts of diarachidonoyl molecular species were found in the phosphatidylethanolamine (10%) and phosphatidylcholine (15%) of HL-60 cells that were labeled for 2 h with 1 × 10 −5 M [ 3H]arachidonic acid. This was the only molecular species of phosphatidylcholine to completely disappear when prelabeled cells were placed in arachidonate-free media for 22 h. Prelabeling-chase experiments with 1 × 10 −5 M [ 3H]arachidonic acid were consistent with movement of [ 3H]arachidonate from triacylglycerols into diradylglycerophosphatides and from diacylphospholipids into ether-linked phospholipids. Increasing the concentration of HL-60 cells in the incubations influenced the distribution of [ 3H]arachidonic acid in cellular lipid classes in a manner analogous to decreasing the concentration of [ 3H]arachidonic acid in the media. Increasing the endogenous level of cellular arachidonate in phospholipid classes with supplements of unlabeled arachidonic acid changed the subsequent lipid class distribution of a low concentration (1 × 10 −8 M) of [ 3H]arachidonic acid to resemble results obtained with a much higher mass level of [ 3H]arachidonate in arachidonate depleted cells. HL-60 cells differentiated into granulocytes by treatment with dimethyl sulfoxide incorporated less [ 3H]arachidonic acid but had a greater proportion associated with alkylacylglycerophosphocholine and alk-1-enylacylglycerophosphoethanolamine than undifferentiated HL-60 cells.

Lipid class distribution and fatty acid composition of wild and farmed prawn, Penaeus monodon (Fabricius)

Total lipid levels of the muscle of wild and farmed Penaeus monodon were similar (4.35% and 4.66% dry weight) whilst head lipid levels (hepatopancreas) were higher in farmed P. monodon (farmed 9.36%, wild 7.07%). The lipids of the muscle of wild P. monodon are mainly composed of phospholipid (70.5%), triglyceride (2.9%) and cholesterol (19.84%). Head lipids have higher triglyceride levels (9.18%) and lower levels of phospholipid (56.7%). Farmed P. monodon muscle lipids had lower levels of phospholipid (57.0%) and higher levels of triglyceride (8.46%) and cholesterol (24.17%) in comparison to wild P. monodon. Head lipids also showed lower phospholipid (39.23%) and higher triglyceride (25.93%). The composition of the phospholipids of wild and farmed P. monodon was similar excepting spingomyelin. The major fatty acids of the muscle phospholipids of wild P. monodon were 16:0 (13.0%), 16:1 (5.3%), 18:0 (13.2%), 18:1 n−9 (8.4%), 18:2 n−6 (1.9%), 20:4 n−6 (12.9%), 20:5 n−3 (13.6%) and 22:6 n−3 (15.5%). Head phospholipids had almost the same profile. Farmed P. monodon phospholipid fatty acids were similar except that levels of 18:2 n−6 (9.8%) were higher and 16:1 (1.79%) and 20:4 n−6 (4.9%) lower. The lipid composition of hatchery and wild post-larvae (approximately post-larvae day 20) was dissimilar. Wild post-larvae lipid was almost entirely phospholipid (68.7%) and cholesterol (27.8%) whilst hatchery stock showed lower phospholipid levels and significant amounts of triglyceride (5.9–15.6%). Comparison of the fatty acids of the phospholipids showed that wild post-larvae had lower levels of 18:1 n−9, 18:2 n−6 and higher levels of 16:1 and 22:6 n−3 (20.4% wild, 4.0% farmed). Analysis of diets fed to farmed P. monodon showed low levels of phospholipid and very high levels of free fatty acids, indicative of dietary lipid deterioration. Diets used for P. monodon are those which have been developed for P. japonicus. Differences, however, exist in the lipid composition and fatty acid profiles of the two wild stocks suggesting differing lipid formulations may be required in diets.

Stepwise chemical degradations of a UK bituminous coal

Organic materials extracted from a UK high volatile bituminous coal, its solvent extracted O-alkylation product and its solvent extracted O-alkylated, LiAlH 4 reduction product have been analysed using g.c.-m.s. to determine changes in the distributions of extractable components with increasing extent of solubilization. Changes in the distribution of functional groups in the insoluble residues have been followed after each step using FT-i.r. Although the range of compounds released at each step is similar, the distribution of extractable lipid classes and their individual components varies. Hopanes (αβ and βα), acyclic isoprenoids, n-alkanes and alkyl phenanthrenes are present in all extracts, with n-alkanes predominating. Maturity parameters based on hopane, phenanthrene and n-alkane distributions give conflicting results for the relative maturities of the three extracts, possibly due to the differential association of individual components within the coal matrix. The organic components extracted after O-alkylation and after LiAlH 4 reduction are likely to arise from the release of physically trapped material as a consequence of cleavage of specific bonds within the coal macromolecular structure.

Lipid composition of the digestive glands of Mytilus edulis and Carcinus maenas in response to pollutant gradients

In field s tuhes for the GEEP Workshop in Langesundfjord. Norway, changes in lipid content and lipid : protein ratios of digestive glands of Mytilus edulis and Carcinus maenas were reflected along the pollution gradient, with populations of M. edulis showing elevations in both parameters at the 3 most contaminated Sites (2, 3 and 4) in comparison to the reference site (l), and populations of C. maenas showing elevations only at Site 3. In mesocosm experiments only M. edulis from the high dose basin showed elevationsin lipid content and lipid : protein ratios; C. maenasin the medium dose basin showed a decrease in both parameters. Analysis of lipid class composition for field and mesocosm samples of M. edulis reveal differences in response to contaminant gradients that reflect alterations in mobilization of triacylglycerols to phospholipid pools, reductions in phospholipid content, and nutritional condition. Changes in lipid class distributions of M. edulis from both field and mesocosm experiments correlate well with body burden data for tissue concentrations of aromatic hydrocarbons and/or polychlorinated biphenyls. Lipid class dstributions of field samples of C. maenasindicate alterations in the mobilization of triacylglycerols, sterol turnover, and reductions in phospholipid content. The responses, which suggest that crabs from Site 3 are the most impacted, are not consistent with contaminant data from the field sites. Crabs from mesocosm expenments show no evidence of alterations in lipid class distribution in spite of a consistent trend in aromatic hydrocarbon tissue concentrations along the gradient. Differential responses of field and mesocosm populations of M edulis and C. rnaenas are possibly the result of metabolic capacity for detoxification and differences in trophic transfer.

Actaptive plasticity of the thylakoid lipids in diuron-resistant Euglena gracilis

The detailed lipid composition of thylakoid fractions isolated from two diuron-resistant strains of Euglena gracilis, which were grown either in the absence or in the presence of the herbicide (at the concentration to which they had been adapted, 25 μM and 250 μM), were compared to those of thylakoids isolated from a control (Z) strain. In all the types of cells studied, differences were found in the distributions of lipid classes as well as in the distributions of fatty acids within these classes, in spite of unchanged amounts of total lipids per chlorophyll unit. Glycerolipids and phosphatidylglycerol were the most perturbed classes. When resistant cells were grown with diuron, the modifications varied as a function of the logarithm of the herbicide concentration. For each resistant strain the deprivation of diuron from the culture medium amplified the differences relative to the control cells. Nevertheless, such an accentuation of the differences was less pronounced for the strain resistant to 250 μM than for the strain resistant to 25 μM diuron, a finding which suggests that the more profound the change induced by the acquirement of resistance (to stronger concentrations of the herbicide), the more stable it was.

Possible correlations between reproductive performance of Stomoxys calcitrans and lipid content of blood diets

1. 1. Adult stable flies were fed blood meal diets of freeze-dried bovine or porcine blood, or fresh bovine or porcine blood, for ten consecutive generations; the reproductive performance of adults fed freeze-dried or fresh porcine blood was significantly higher ( P < 0.05) than that of adults fed freeze-dried or fresh bovine blood. 2. 2. Quantitative analyses of cholesterol, triglycerides, phospholipid phosphorus, phospholipid classes, and fatty acid composition of the diet were made. 3. 3. There was no direct correlation between the percentage distribution of lipid classes and the fecundity of flies. However, the locations of phosphatidyl choline and sphingomyelin within the blood components may be a factor in the diet.

Fatty acid composition of ethanolamine phosphoglycerides in different areas of the gerbil brain after chronic exposure to trichloroethylene.

Exposure of Mongolian gerbils to trichloroethylene (TCE) (320 ppm) in an inhalation chamber continuously for 3 mo resulted in an altered fatty acid pattern of phospholipid in discrete areas of the brain. Lipids were extracted from four brain regions: the cerebral cortex, the hippocampus, the cerebellar vermis posterior, and the brain stem. No changes induced by TCE were found in lipid class distribution among the different regions examined. Whole brain weights and weights of the dissected pieces were also unchanged. In ethanolamine phosphoglycerides from the cerebral cortex and the hippocampus, a decrease was found among long-chain fatty acids derived from linolenic acid with a corresponding increase of the linoleic acid family. The cerebellar vermis and the brain stem were less affected. Since areas rich in gray matter were affected more than those with a high proportion of white matter, it seems reasonable to assume that the fatty acid alterations of ethanolamine phosphoglycerides occur mainly in the gray matter. Furthermore, we suggest that the alterations can be a compensatory mechanism for the membrane fluidizing properties of TCE.

Lipid class and molecular species interrelationships among plasma lipoproteins of normolipemic subjects

As evidence of lipoprotein interconversion and/or equilibration, a gas-liquid chromatographic (GLC) examination was made of the lipid class and molecular species interrelationships among the major fasting plasma lipoprotein fractions within each of seven male and four female normolipemic subjects subsisting on free choice diets. The lipoprotein fractions were prepared by conventional ultracentrifugation and the lipid class and molecular species composition of the corresponding lipoprotein fractions were determined by GLC of the intact cholesterol and glycerol esters and of ceramides. In general, each lipoprotein fraction possessed a well defined lipid class composition, which was characterized by a dramatically decreasing triacylglycerol and an increasing phospholipid and cholesteryl ester content when progressing from the very low (VLDL), to the low (LDL 2) and high (HDL) density lipoproteins, as already established by conventional analyses. However, the LDL 2 contained about a two times higher proportion of total phospholipids as sphingomyelin than VLDL and HDL. Furthermore, the sphingomyelins of the HDL fraction contained about 30% more of the higher molecular weight species than the sphingomyelins of either VLDL or LDL. Smaller differences were seen in the molecular species composition of the phosphatidylcholines, cholesteryl esters and triacylglycerols among the corresponding fractions of lipoproteins. In general, the lipid class and molecular species distribution is incompatible with the hypothesis which postulates VLDL conversion into LDL and HDL under the influence of lipoprotein lipase and lecithin:cholesterol acyltransferase. The significant differences noted in the lipid class and molecular species distribution suggest that the true transformations of the lipoproteins are much more complex and may also involve cholesteryl ester-triacylglycerol, triacylglycerol and phosphatidylcholine exchanges via appropriate carrier plasma proteins, as well as possible phase separation of lipids during the removal of the excess surface material from the VLDL remnants, as already demonstrated in in vitro experiments. It is concluded that a direct GLC analysis of the neutral and polar lipid components of plasma lipoprotein classes provides important evidence of lipoprotein interrelationships which may be utilized to test existing and new hypotheses of lipoprotein interconversion.

The composition of the skin surface lipids of European cattle and buffalo steers

1. 1. This study compared the composition of the skin surface lipids (SSL) of cattle ( Bos taurus) and of buffalo ( Bubalis bubalis) steers at the same level of feed intake in a thermoneutral environment. 2. 2. There was about eight times less lipid per unit area of skin surface on the buffalo than on cattle. 3. 3. The distribution of the different lipid classes in the SSL of the two breeds was different. Compared to cattle, the buffalo SSL was characterized by smaller proportions of wax ester bands 2 and 3 and triglycerides. 4. 4. There were significant species differences in the fatty acid patterns of the individual lipid classes. 5. 5. The results are discussed in relation to the functional attributes of sebum.

Lipid transport mechanism in the prawn.

The distribution of radioactive lipid classes in the tissues of prawn, Penaeus japonicus, was investigated after oral administration of linolenic acid-1-14C in order to clarify the mechanism of lipid transport in crustaceans. Also, the movement of linolenic acid to the serous membrane site across the hin-dgut was examined by using the everted hind-gut of prawn. Dietary free fatty acid was presumed to be mainly absorbed at the region of the hepatopancreas and mid-gut rather than at the hind-gut. The absorbed linolenic acid was resynthesized to phospholipids (PL) in the hepatopancreas and hind-gut, and then released into the hemolymph as a form of PL. From this data, PL were conceived to be the most important mediators of lipid mobilization through the hemolymph in the prawn, P. japonicus.

Lipid composition of commercially canned single‐strength orange juice

AbstractThe lipid composition of commercially canned single‐strength orange juice ranged from 84–101 mg/100 ml juice (overall mean 95 ± 6). Phospholipid phosphorus, expressed as mg/100 ml juice, showed a range of from 1.56–1.95, while phospholipid phosphorus/lipid values (as µg‐P/mg lipid) were within a very narrow range, 18.9 ± 1.1. The percentage distribution of lipid classes in these juices was 24–35% neutral lipids, 18–23% resin acids and glycolipids, and 43–53% phospholipids and other polar lipids. Five fatty acids, i.e. C16, C16:1, C18:1, C18:2, and C18:3, accounted for over 93% of all fatty acids. The relative percentages of C18:2 and C18:3 differed between seasonal juices. The lipid composition does not warrant inclusion in nutritional labeling; however, lipid levels may be useful in detecting adulteration.

Fatty acid composition of lipids in some species of marine algae.

The distribution of lipid classes and their fatty acid composition in Codium fragile, Gracilaria vercosa, Undaria pinnatifida and Sargassum spp. were examined. Total lipids constituted from 1.3 to 1.9 per cent of dry blades, and 2.7 per cent in sporophylls of U. pinnatifida. The acetone soluble lipid content exceeded that of acetone insoluble lipid in all seaweeds studied, especially in sporophylls of U. pinnatifida. In the blades of seaweeds other than C. fragile, the free fatty acid fraction exceeded the trigly-ceride fraction, while the reverse was true in blades of C. fragile and sporophylls of U. pinnatifida. Fatty acids, C16:1 (isomer of palmitoleic acid) in Undaria, C16:3 in Codium and C20:4 in Gracilaria seemed to be characteristic for each seaweed. The sporophylls of Undaria showed a distribution of lipid classes and fatty acid composition different from those in the blades of seaweeds studied. Some unsaturated fatty acids were found to occur in higher proportions in certain seaweeds: [C16 and C18 acids in Codium, C16 acid in Undaria, and C16 and C20< acids in Gracilaria.] In polar lipid fractions, C20< acids occurred in relatively high proportions in all seaweeds tested.

Lipid class distribution and fatty acid composition of prawn, Penaus japonicus bate.

Ovary, hepatopancreas and muscle of prawn, Penaeus japonicus Bate, were analyzed for lipid class distribution. Ovary and hepatopancreas are the main lipid storage organs, triglycerides being their major lipid component while muscle contains mainly cholesterol and phospholipids. The fatty acid composition of prawn was similar to that in other marine animals, palmitic acid and ω 3 polyunsaturated fatty acids predominating in both males and females. However, the ovary of female prawn contains more monounsaturated fatty acids than do the other parts of the body. It is certain that this is related to the elaboration of triglycerides as energy reserves in this organ.

Depth Distribution of the carotenoid pigments and lipids of some oceanic animals. 2. Decapod Crustaceans

SummaryAnalysis of the carotenoid pigments of decapod crustaceans has indicated that the visible differences in the appearance of species from different depth horizons are largely due to the disposition of pigments and not to differences in total amount of pigment relative to body size. Species from the upper mesopelagic zone have relatively few large chromatophores, and their chitin is either unpigmented or feebly pigmented. Species from deeper zones have very many small chromatophores and chitin heavily pigmented by unesterified astaxanthin. The major carotenoid pigments of almost all species are astaxanthin and its esters.Lipid analyses have shown that several species of Caridea have very high levels of lipid in the body, and that in many deep-water species wax esters comprise a large proportion of the total lipid. Specific patterns of distribution of the various lipid classes are found in different tissues, with wax esters particularly dominating the hepatopancreas lipids of deep-living species.The patterns of pigment and lipid distribution are discussed in relation to the depth distribution, light environment, and metabolic requirements of the different species.

The Lipid Composition of a Species of Alternaria of the “Alternaria Alternata Group”

(1973). The Lipid Composition of a Species of Alternaria of the “Alternaria Alternata Group”. Mycologia: Vol. 65, No. 4, pp. 958-963.

Lipid binding in mitochondria from testes of normal and essential fatty acid deficient rats.

AbstractEssential fatty acid (EFA) deficiency in rat causes severe degeneration of spermatogenic tissue. Previously it was shown that the distribution of lipid classes changes very little during tissue degeneration. However it is well known that the fatty acid spectrum in lipids from testicular tissue is altered drastically during EFA deficiency. The molecular binding of lipids in membrane structures might be altered when a larger amount of ω9‐acids is present in the various lipid classes in testes of EFA‐deficient rats. In the present studies comparison was made of the binding of lipids in testicular mitochondrial membranes from rats fed a fat‐free diet or a diet containing 6% peanut oil for 26 weeks. Isolated mitochondria were coated on glass beads, then dried and packed into a column, whereafter the membrane lipids were eluted with solvents with increasing dielectric constants. The differences between the binding of lipid classes in supplemented and EFA‐deficient rats were not pronounced, but a tendency to a weaker binding in the EFA‐deficient rats was observed. However for both groups the various extracts showed marked differences in the distribution of lipid classes concurrent with the change of the eluent. This indicates a different kind of binding in the membrane, not only for different lipid classes, but also within a special lipid class. Thus both phosphatidylcholines (PC) and phosphatidylethanolamines (PE) were found in extracts with quite different dielectric constants. The fatty acid composition of PC and PE in the major fractions eluted with chloroform and ethanol, respectively, was essentially the same. This indicates that the successive release of phospholipids (PL) in these two fractions was not based on fatty acid solubility properties but on variable binding in the membrane structure. The introduction of ω9‐polyenoic fatty acids instead of ω6‐polyenoic fatty acids in the PL of mitochondria membranes from EFA‐deficient rats seems to be the only deviation in the lipid pattern of EFA‐supplemented and EFA‐deficient animals, and might therefore be responsible for the symptons of EFA deficiency.

Essential fatty acid-deficient rats. 3. Distribution of lipid classes in rat testes after feeding partially hydrogenated oils.

AbstractTotal and relative amounts of neutral lipids (NL) and phospholipids (PL) as well as the distribution of various lipid classes in these were determined in testes of rats fed different types of partially hydrogenated oils for 5,15 and 26 weeks. The dietary fats were partially hydrogenated arachis oil (HAO), partially hydrogenated soybean oil (HSO), partially hydrogenated herring oil (HHO) and, for comparison, arachis oil (AO). An additional series of animals was reared on a fat‐free diet throughout the entire experiment. The total amount of NL is decreased by EFA deficiency parallel with the development of the degenerative changes of the spermatogenic tissue. The relative amounts of NL in the testis are not influenced by EFA deficiency during the first stages of degeneration. However, feeding of HHO for 26 weeks resulted in a marked decrease in NL. The total content of PL is directly related to tissue degeneration. This observation is supported by the data obtained after 5 weeks of feeding HHO and by the correspondence between the results found after 15 and 26 weeks on HAO and the fat‐free diets, respectively. The relative amount of PL is less influenced by EFA deficiency, but severe degenerations as found for the group fed HHO are followed by decreases. The neutral lipids had three main fractions: triglycerides (TG), free fatty acids (FFA) and cholesterol (Chol). FFA was found to be the main fraction of NL after 5 weeks, whereas TG was the main component of NL after 15 and 26 weeks, especially in the animals with degenerated testes. The presence of the large quantities of FFA is discussed. Cholesterol was decreased markedly in the EFA deficient rats fed partially hydrogenated oils, but not in the fat‐free reared groups. The variations in the PL distribution during the experiment were small with regard to the two main PL classes, the phosphatidylcholines and the phosphatidylethanolamines. The most remarkable change among the PL classes was an increase in the percentage of sphingomyelins when the spermatogenic degenerations developed.