Lipid composition of ten edible seed species from North Vietnam

The lipid composition and oil content of ten edible seed species from North Vietnam(Cassia tora, Ipomoea aquatica, Raphanus sativus, Citrullus lanatus, Cucumis melo, Cucurbita pepo, Luffa cylindrica, Phaseolus vulgaris, Vigna aurea, Sesamum orientale) have been investigated. The contents of hydrocarbon, triacylglycerol, free fatty acid, sterol, di- and monoglycerol, and polar lipid fractions have been determined with a thin-layer chromatography (TLC)/flame-ionization detection analyzer. Molecular species of hydrogenated triacylglycerols and the fatty acid composition of total lipids also have been analyzed by capillary gas-liquid chromatography. The quantities of major phospholipid classes of four seed species(C. tora, I. aquatica, R. sativus, V. aurea) have been determined by two-dimensional TLC and the spectrophotometrical phosphorus analysis. The fatty acid compositions of nonpolar and polar lipid fractions of these four species also have been analyzed.     

A comparison of lipids from liver and hepatoma subcellular membranes

Subcellular fractions of nuclei, mitochondria, endoplasmic reticulum, plasma membrane and cytosol were prepared from liver and hepatoma 72288CTC. Marker enzyme activities, biochemical compositions and electron microscopy were used to establish purity. Hepatoma NADH: cytochrome C reductase and 5′-nucleotidase exhibited abnormal subcellular distributions. The lipids from the subcellular fractions were examined in detail. Mitochondria and plasma membranes were characterized by elevated percentages of diphosphatidylglycrerol and sphingomyelin, respectively, in both tissues. All hepatoma subcellular fractions contained dramatically elevated levels of sphingomyelin and cholesterol, two components that form preferential strong complexes in vitro. The fatty acid composition of hepatoma sphingomyelin differed markedlg from liver and, unlike liver, did not exhibit organelle specific compositions. Some hepatoma lipid classes contained reduced percentages of palmitate while others contained higher levels. Hepatoma phosphatidylcholine and phosphatidylethanolamine from organelles contained lower percentages of long chain polyunsaturated fatty acids than liver. Generally, unique fatty acid profiles exhibited by individual phospholipid classes of liver subcellular fractions were absent or much reduced in the hepatoma. The ratios of oleate to vaccenate were near one for most of the phospholipid classes of most liver fractions, but all hepatoma classes, with few exceptions, contained a much higher percentage of oleate in all subcellular fractions. The hypothesis is proposed that the origin of some acyl moieties for the biosynthesis of various hepatome lipid classes differs from liver sources. The possible changes in acyl pools, sources and compartments for complex lipid biosynthesis could result in change in the quantities of molecular species that could contribute to the abnormal properties of the hepatoma membranes.     

Lipids of subcellular particles

Methods for isolation and characterization of subcellular particles as well as procedures for analysis of lipid class composition are discussed. The literature on distribution of lipids in subcellular particles is then reviewed. Pertinent new data from our laboratories are presented as well. The isolated particles are related to the organelles to which they correspond in the cell and are discussed with regard to heterogeneity and morphological integrity. Confusion can arise with regard to subcellular particles unless it is appreciated that: 1) preparation of particles of high purity generally requires more than the classical differential centrifugation scheme (both differential and gradient centrifugation may be required); 2) it is hazardous to apply exactly the same procedure for all tissues; 3) all subcellular fractions must be thoroughly characterized. The more recently devised DEAE cellulose column and thin-layer chromatographic procedures for analysis of lipid class composition are more reliable than the older hydrolytic or silicie acid column or paper chromatographic techniques. The chief lipid components of mitochondria from all organs and species are lecithin, phosphatidyl ethanolamine, and cardiolipin (diphosphatidyl glycerol). Despite the fact that reports in the literature are in agreement that phosphatidyl inositol is a major component of mitochondria, it is concluded on the basis of new data obtained from highly purified mitochondria and improved analytical methods that phosphatidyl inositol is not a major component of mitochondria. The presence of a relatively large amount of phosphatidyl inositol in mitochondrial preparations is probably related in part to contamination with other particles. Some analytical procedures are demonstrated to give erroneous values for this lipid class. It is also concluded that phosphatidyl serine, phosphatidic acid, sphingomyelin, cerebrosides, and lysophosphatides, reported to occur in mitochondria, are not characteristic mitochondrial components and furthermore that the large amount of uncharacterized mitochondrial phospholipid reported is actually an analytical artifact. Microsomes appear to be similar to mitochondria except that cardiolipin is either low in or absent from microsomes. Available data indicate nuclei to be rather similar to mitochondria and microsomes, at least in some organs. Studies of the fatty acids of subcellular particles indicate that different particles from one organ have very similar fatty acid compositions. It is clear that there are marked variations in fatty acid composition of particles from different organs and from different species. Differences in dietary fat may be associated with marked changes in fatty acid composition, although brain mitochondrial lipids are largely unchanged. Each lipid class from mitochondria of most organs appears to have a fairly characteristic fatty acid composition. Cardiolipin from some organs contains primarily linoleic acid, phosphatidyl ethanolamine contains large amounts of linoleic and higher polyunsaturates, and lecithin is similar to phosphatidyl ethanolamine except that it does not contain as much arachidonic acid and/or other highly unsaturated fatty acids. New data, the first to be reported, are presented for heart mitochondrial cardiolipin, phosphatidyl ethanolamine, and lecithin. It is concluded that there are two basically different types of membranous structures. Myelin is the chief representative of the metabolically stable type of membrane structure while mitochondria represent the more labile type. The two types of membranes have very different in vivo properties and very different lipid compositions. Myelin is characterized by a high content of cholesterol and sphingolipids with more long chain saturated or monoenoic fatty acids while mitochondria are characterized by a low cholesterol content, little or no sphingolipid, and highly unsaturated fatty acids. It is clear that formulations of the myelin type membrane structure such as that of Vandenheuvel cannot apply to mitochondria. It is postulated that membrane structures intermediate between the extremes represented by myelin and mitochondria exist.     

Species variations in phospholipid class distribution of organs: II. Heart and skeletal muscle

Total lipid, lipid phosphorus and phospholipid class distribution were determined for heart and skeletal muscles from five vertebrates (human, bovine, rat, mouse and frog) and skeletal muscles from four invertebrates (lobster, abalone, scallop and sea urchin). The precision of the analytical method [separation by two-dimensional thin layer chromatography (TLC) and phosphorus analysis of spots] was demonstrated by small values for standard deviations. Accuracy of spot identification and analytical values was insured by comparison with results obtained by TLC of triethylaminoethyl cellulose column chromatographic fractions. Values for total lipid, total phospholipid and phospholipid class distribution of heart and skeletal muscles from the five vertebrate species showed essentially the same variability observed for the same organ from different animals of one species (rat). The data indicate that, among vertebrates there is little or no variability for phospholipid class distribution in muscle membranes in agreement with data for other organs and subcellular particulates presented in other reports. Invertebrate skeletal muscles were found to differ qualitatively and/or quantitatively from those of vertebrates. In one species (sea urchin), ceramide phosphorylethanolamine was the only sphingolipid, sphingomyelin characteristic of vertebrates being absent. In two species (abalone and scallop) ceramide aminoethylphosphonate was present and sphingomyelin was absent. In one (lobster), sphingomyelin was the only sphingolipid. Quantitatively, higher levels of sphingolipid and phosphatidyl serine and lower levels of phosphatidyl inositol were found in invertebrate skeletal muscle. The significance of the data is discussed in relation to subcellular particulate lipid class composition.     

Plasma membrane lipids of bovine adrenal chromaffin cells

The lipid composition of plasma membranes isolated from bovine adrenal chromaffin cells has been determined. Choline and ethanolamine phosphatides were predominant; the level of lyso compounds was very low. The amount of cholesterol and the cholesterol/phospholipid molar ratio was low compared to those of the other subcellular fractions of chromaffin cells. A complex pattern of neutral glycolipids was observed in contrast to that of gangliosides.     

Lipid composition of 30 species of yeast

The detailed composition of cellular lipid of more than 23 species of yeast has been determined quantitatively by thinchrography on quartz rods, a method previously used for estimating cellular lipids of seven species of yeast. That data was fortified by neutral and phospholipid quantitations on 30 species of yeast cells. Most of the test organisms contained 7–15% total lipid and 3–6% total phospholipid per dry cell weight, except for the extremely high accumulation of triglycerides in two species ofLipomyces. Qualitatively, 30 species of yeast cells contained similar neutral lipid constituents (triglyceride, sterol ester, free fatty acid, and free sterol) and polar lipid components (phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol, cardiolipin, and ceramide monohexoside) without minor constituents. Based on the quantitative composition of neutral lipids, the 30 species of yeast were divided into two groups, the triglyceride predominant group and the sterol derivative group. These groupings were fairly well overlapped from the standpoint of the distribution characteristics of fatty acid. The relative polar lipid compositions also grossly resembled each other. Only one exception of polar lipid composition in yeast cells was found inRhodotorula rubra species which contained phosphatidyl ethanolamine as the most abundant phospholipid. Fatty acid distribution patterns in yeast cells consistently coincided with other reports concerning fatty acid composition of yeast cells. Correlation of lipid composition and classification of yeasts are suggested and discussed. A part of this investigation has been reported at the 14th conference of the Japan Oil Chemists' Society, Nagoya, Japan, October 1975.     

Lipid and fatty acid composition of different fractions from rat urinary transitional epithelium

The phospholipid composition of rat urinary transitional epithelium (TE) and the fatty acid composition of microsomal, mitochondrial, cytosolic, and plasma membrane (PM) subcellular fractions were investigated. PM marker enzymes and electron microscopy analysis were used to characterize the PM fraction, which showed a distinctive lipid composition compared to the general profile of PM from different sources. The levels of cholesterol and sphingomyelin were not enriched in the PM fraction; on the other hand, the increased amounts of glycosphingolipids and phosphatidylserine, and the decreased level of phosphatidylcholine followed the general features of a PM profile. This differential PM lipid composition may reflect the unique morphology of this mammal TE, consisting of concave plaques with an asymmetrical membrane unit. The distribution of the double bond across the PM indicated a higher unsaturation of the inner relative to the outer part of the PM hemileaflet. In addition, the presence of 20∶3n−9 nonessential fatty acid in a normal TE may represent a characteristic fatty acid metabolism of this epithelium. The authors wish to dedicate this work to the memory of the late Professors Benito Monis, who participated in the generation of this research and whose working hypothesis remains a source of fruitful inspiration.     

Lipid composition of further purified bovine liver nuclear membranes

The lipid content, distribution and fatty acid composition of highly purified bovine liver nuclear membranes was determined and compared to those of microsomes prepared in parallel. Contrasted with microsomes, nuclear membranes while containing nearly the same levels of lipid had more cholesterol and total neutral lipid and less phospholipid. Phospholipid and neutral lipid patterns generally were similar for the two types of membranes. The same fatty acids, in similar proportions, were observed in respective total lipid, total polar lipid, phosphatidyl choline and phosphatidyl ethanolamine fractions of the two membrane types. The microsomal lipid fractions contained slightly greater percentages of unsaturated fatty acids. With respect to previous results from preparations contaminated with nonmenbranous nuclear material, purified fractions contained more total lipid on a protein basis and more total unsaturated fatty acids. Only minor differences in levels and distribution of phospholipids and neutral lipids were observed between the crude and highly purified fractions. Purdue University AES Journal Paper No. 4482.     

Fatty acid composition of adultSchistosoma mansoni

The fatty acid composition of triglyceride and total phospholipid fractions of adultSchistosoma mansoni has been examined. Both triglyceride and phospholipid contained fatty acids varying in chain length from 12 through 24 carbons; trace amounts of shorter chain components were found in the triglyceride fraction. A docosahexaenoic acid in the triglyceride fraction represented the highest degree of unsaturation encountered. Branched chain fatty acids of 16 and 18 carbons were found in both phospholipid and triglyceride. Examination of fatty acids from fluke total lipid revealed the presence of small amounts of odd numbered carbon fatty acids varying in chain length from 13 through 23 carbons.     

On the phospholipids ofCulex pipiens fatigans

The lipids of different developmental stages ofCulex pipiens fatigans, vector of bancroftian filariasis, have been investigated. The phospholipid composition of the developmental stages and of the subcellular fractions of fourth instar larvae of the insects were analyzed. The composition of fatty acids and their positional distribution have also been examined in the major phospholipids of the larvae. The insect eggs contained higher amounts of lipids than larvae suggesting that they were utilized during embryogenesis. Phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) comprised over 75% of the insect phospholipids. Of these, PE was present in the greatest amounts during all stages of growth and in the subcellular fractions of larvae. An ethanolamine containing sphingolipid was found as a component of the phospholipids of the insects. About 50% of the lipids of the larvae were localized in the cell debris and nuclei fraction which also contained most of the lysolipids of the insects. As in other Diptera 16∶0, 16∶1 and 18∶1 were the major fatty acids present in the insect lipids of which the fatty acid found in greatest amounts was 16∶1. Similar to the phospholipids of animal species, saturated fatty acids were predominantly linked to the 1 position of the major phospholipids of the insects while the unsaturated fatty acids were in higher amounts at the 2 position.     

Lipids of the Antarctic sei whale,Balaenoptera borealis

The blubber, liver, and muscle of the Antarctic sei whale were analyzed for total lipid content, composition of lipid by classes and positional distribution of fatty acids in individual lipids. The major glycerolipids (triglycerides, phosphatidylcholine, and phosphatidylethanolamine) were fractionated by silver nitrate thin layer chromatography. The phospholipid fractions were analyzed for fatty acid positional distribution. The whale stomach contained almost exclusively the amphipodParathemisto gaudichaudi. Its lipids were also studied and compared with the lipids of the body tissues. The results indicate that the stomach content lipids are subjected to modifications before being deposited in the blubber, liver, and muscle. According to the silver nitrate thin layer chromatographic studies, liver and blubber triglycerides resemble each other in their patterns of positional distribution of fatty acids and in molecular species composition. The phospholipids of liver and blubber also exhibited closely related fatty acid distribution patterns. In general, while the proportions of lipid classes and their predominant fatty acids varied from tissue to tissue, the patterns according to which the lipids had been synthesized seemed to be common. “...And beneath the effulgent Antarctic skies I have boarded the Argo-Navis, and joined the chase against the starry Cetus far beyond the utmost stretch of Hydrus and the Flying Fish.” (1).     

On the membrane phospholipids and their acyl group profiles of adrenal gland

The phospholipid composition and their acyl group profiles from subcellular fractions of guinea pig adrenal gland and the same fractions from the cortex and medulla of the bovine gland were compared. The phospholipids of guinea pig adrenal were enriched in diacyl-glycerophosphocholines (GPC) which comprised over 50% of the total phospholipids, but the proportions of ethanolamine and choline plasmalogens, sphingomyelin and diacyl-glycerophosphoserine (GPS) were lower in guinea pig adrenals as compared to the bovine adrenals. In the bovine adrenal, sphingomyelin and diacyl-GPS were enriched in the medulla, whereas diacyl-glycerophosphoinositol (GPI) were enriched in the cortex. Although lysolecithin was present (up to 4.5%) in the bovine adrenal, only trace amounts of this lipid were detected in the guinea pig adrenal. Characteristic acyl group profiles were found associated with each type of the phosphoglycerides in adrenal membranes. However, acyl group profiles of the phosphoglycerides were not greatly different either between the bovine and guinea pig adrenal or with respect to the type of subcellular membranes isolated. Diacyl-GPC were enriched in 16∶0 and 18∶1, but also contained considerable amounts of 18∶0, 18∶2 and 20∶4. Diacyl-GPE were enriched in 18∶0, 18∶1 and 20∶4, while diacyl-GPI, diacyl-GPS, as well as alkenylacyl-GPE, were enriched in 20∶4. The lysolecithin from bovine adrenal membranes contained mainly 16∶0, 18∶0 and 18∶1 with only trace amounts of the polyunsaturated fatty acids. Other polyunsaturated fatty acids, such as 22∶4 and 22∶6, are apparently not prominent in the phosphoglycerides from either the bovine or the guinea pig adrenal gland.     

Phospholipids of the pulmonate land snailCepaea nemoralis (L.)

The phospholipids of the snailCepaea nemoralis, comprising the major lipid fraction (65%) in this terrestrial pulmonate, were investigated by thin-layer and column chromatography. Detailed gas chromatographic analyses of liberated fatty acid fractions and amino acid analyses of the water soluble moieties of isolated phospholipid classes were carried out. Phosphatidyl choline (47%) and phosphatidyl ethanolamine (21%) were found to be the predominant phospholipid classes, while phosphatidyl serine (8%), phosphatidyl inositol (6%), diphosphatidyl glycerol (3%), ceramide amino-ethylphosphonate (7%), lysophosphatidyl choline (1%), and phosphatidic acid (1%) were present in lesser amounts. In the phosphatidyl ethanolamine and phosphatidyl serine fractions, minor quantities of plasmalogen analogues were detected. Fatty acid profiles of the various phospholipid classes appeared to be strikingly diverse, e.g. a characteristic component, such as linoleic (18∶2ω6) acid, ranging from 3–54%. In vivo radioisotope studies using 1-¹⁴C-acetate demonstrated the high biosynthetic rate of all phospholipid classes and their respective fatty acid fractions. Results are discussed in relation to data on the phospholipids from other invertebrate species.     

Lipid composition and peroxide levels of mucosal cells in the rat large intestine in relation to dietary fat

To examine whether dietary fat alters membrane lipid composition and peroxidation of polyunsaturated fatty acids in “non-proliferative” and “proliferative” cells in the large intestine, Sprague-Dawley rats were fed diets providing a polyunsaturated-to-saturated fatty acid ratio of 1.2 or 0.3 at a high or low level of fat intake for a 25-day period. Cell populations were isolated and the effect of dietary fat on membrane polyunsaturated fatty acid content and peroxide levels was determined. Neither fat level nor fatty acid composition of diet influenced total cholesterol, total phospholipids, and percentage of phospholipid classes in membrane phospholipids. Feeding the high fat and/or high polyunsaturated-to-saturated fatty acid ratio diet increased polyunsaturated fatty acid content of mucosal cell phospholipids. Increase in polyunsaturated fatty acid content was paralleled by a decrease in the monounsaturated fatty acid content of mucosal cell phospholipids. Membrane content of total saturated fatty acids was not significantly affected by diet. Variation in phospholipid fatty acid composition between “non-proliferative” and ”proliferative” cells was observed. Lipid peroxide levels in mucosal cell lipid fractions were altered by dietary fat treatment. Animals fed high fat diets, compared to groups fed low fat diets, exhibited higher membrane peroxide levels when results are expressed as nmol/mg protein. Higher peroxide levels were observed in mucosal cells for rats fed high polyunsaturated-to-saturated fatty acid ratio diets when results were expressed per nmol of phospholipid. It is concluded that changes in fat level and fatty acid composition of the diet alters the mucosal cell membrane lipid composition in the rat large intestine and influences susceptibility of mucosal cell lipid to peroxidation. Further research is required to delineate which dietary factors—fat level, polyunsaturated-to-saturated fatty acid ratio, or both—have a primary influence on the degree of lipid peroxidation.     

Analysis of subcellular phosphatidyl choline in developing rabbit lung

Phosphatidyl choline is a major lung surfactant. Insufficient development of the surfactant in neonates is often associated with the Respiratory Distress Syndrome. The concentration and fatty acid composition of phosphatidyl choline have not been studied in the subcellular organelles of the developing lung. This study has investigated the development of the concentration and fatty acid composition of phosphatidyl choline in subcellular fractions of 28-day and 30-day fetal and maternal New Zealand rabbit lungs. The concentration of total phospholipids in lamellar bodies increased four to five fold from 28-day fetus to 30-day fetus which, in turn, was similar to the maternal level. Total phospholipid content increased only about 50% in mitochondria and microsomes. The percentage of phosphatidyl choline among total phospholipids in lamellar bodies increased successively from 60% at 28 days gestation to 84% at 30 days gestation and leveled at 84% in maternal lamellar bodies. Microsomal PC increased steadily from 52% in the 28-day fetus to 65% in the adult. Analysis of the fatty acid composition of phosphatidyl choline in lamellar bodies confirmed 16∶0 as the major fatty acid, and its content remained constant from 28 days gestation to adult. In contrast, the content of 16∶0 of the microsomal phosphatidyl choline decreased with increasing gestation. Changes of several unsaturated fatty acid components were observed in both lamellar bodies and microsomes in the developing lungs. Maturational development of phosphatidyl choline is reflected in an increase in the concentration of this surfactant, particularly in lamellar bodies, and possibly in remodeling of fatty acid composition in both lamellar bodies and microsomes.     

Lipid composition of liver mitochondria and microsomes in hyperthyroid rats

Triiodothyronine-induced alteration of the lipid pattern in rat-liver mitochondria and microsomes has been investigated. In mitochondria, a 25% total cholesterol decrease and a 14% phospholipid increase have been detected. In these hyperthyroid rat liver organelles, a strong decrease in the total cholesterol/phospholipid molar ratio occurs. On the contrary, in microsomes from the same animals, a decrease of about 23% has been measured for both total cholesterol and phospholipids; hence, in this fraction, the total cholesterol/phospholipid molar ratio is unaffected by hyperthyroidism. The liver mitochondrial phospholipid composition, unlike the microsomal composition, is altered significantly in hyperthyroid rats; a 7.4% phosphatidylcholine decrease is accompanied by a similar additive percentage increase of both phosphatidylethanolamine and cardiolipin. In regard to total phospholipid fatty acid composition in liver microsomes from hyperthyroid rats, no variation has been observed compared with the control rats, whereas in mitochondria from the same animals, a meaningful linoleic acid decrease with a similar arachidonic acid increase has been found. In addition to fatty acid alteration, the separated mitochondrial phospholipid classes also exhibit some increase in stearic acid. Among phospholipids, cardiolipin changes the most of the esterified fatty acids in hyperthyroid rat liver. In this compound, a strong increase in the percentage of both palmitic and stearic acid and a 32.4% decrease of linoleic acid have been found.     

Acyl lipid metabolism in the oleaginous yeastRhodotorula gracilis (CBS 3043)

The effects of culture conditions on acyl lipid metabolism in the oleaginous yeastRhodotorula gracilis (CBS 3043) have been investigated. Growth ofR. gracilis under conditions of nitrogen-limitation resulted in the accumulation of large quantities of triacylglycerols. Thin layer and gas chromatographic analysis of total lipid extracts revealed that the majority of this storage lipid was produced by stationary-phase cells. In contrast, no such increase in triacylglycerol biosynthesis could be detected in carbon-limited cells. Freeze-fracture electron microscopy evidence supported these findings. Growth medium composition was found to have little effect on the relative abundance of the primary phospholipid classes present inR. gracilis. The acyl compositions of triacylglycerols were similarly unchanged by alterations in the composition of the growth medium. In contrast, the degree of unsaturation exhibited by the phospholipid fractions appeared to be particularly sensitive to this external parameter. Acyl quality of triacylglycerol pools extracted from nitrogen-limited cells were observed to become increasingly saturated as cultures increased in age. Growth of nitrogen-limited cells at a lower growth temperature was observed to have little effect on triacylglycerol accumulation. However, both triacylglycerol and phospholipid fractions extracted from these cultures were found to contain increased proportions of the polyunsaturated fatty acid, α-linolenate.     

The lipid composition of erythrocytes in european cattle and buffalo steers

This study compared the lipid composition of the red blood cells of European cattle and of buffalo steers at the same level of feed intake in a thermoneutral evironment. The mean volumes of the erythrocytes and their lipid content were greater in buffalo than those in cattle. However, the amounts of phospholipid and cholesterol in cells of equal volume were higher in buffalo than in cattle. In contrast, the phospholipid level at a given cholesterol level was higher in cattle than in buffalo. The distribution of the different molecular species of phospholipids in the red cells of the two breeds were similar, but there were significant distinctions in their fatty acid patterns, notably in the levels of 24∶0 and 24∶1 in the sphingomyelin fractions. The proportion of total monounsaturated acids in the erythrocytes were similar from both breeds. However, there was a higher percentage of polyunsaturated fatty acids with a corresponding lower content of total saturated fatty acids in the red cells from buffalo than in those from cattle. The breed differences in erythrocyte lipid composition are discussed in relation to breed differences in red cell characters and could lead to a better understanding of the mechanisms of environmental adaptation.     

A unique lipid pattern associated with the gall bladder bile of the chick embryo

A study has been made of the lipid and fatty acid composition of the gall bladder bile of the chick embryo during the last week of incubation. The lipids and their fatty acid composition showed a unique pattern when compared to other animal species. Of the total lipid present, phospholipid accounted for less than half, and there were substantial proportions of both cholesteryl ester and triglyceride. In the cholesteryl ester, the proportion of which increased significantly over the last week of incubation, there was a very high level of oleic acid. The phospholipid contained a high level of arachidonic acid. The results are discussed in relation to observations on the biliary lipids of other animal species and the major features of the lipid metabolism of the chick embryo during the last week of incubation.     

The effect of dietary arachidonic acid on plasma lipoprotein distributions, apoproteins, blood lipid levels, and tissue fatty acid composition in humans

Normal healthy male volunteers (n=10) were fed diets (high-AA) containing 1.7 g/d of arachidonic acid (AA) for 50 d. The control (low-AA) diet contained 210 mg/d of AA. Dietary AA had no statistically significant effect on the blood cholesterol levels, lipoprotein distribution, or apoprotein levels. Adipose tissue fatty acid composition was not influenced by AA feeding. The plasma total fatty acid composition was markedly enriched in AA after 50 d (P<0.005). The fatty acid composition of plasma lipid fractions, cholesterol esters, triglycerides, free fatty acids, and phospholipid (PL) showed marked differences in the degree of enrichment in AA. The PL plasma fraction from the subjects consuming the low-AA diet contained 10.3% AA while the subjects who consumed the high-AA diet had plasma PL fractions containing 19.0% AA. The level of 22:4n-6 also was different (0.67 to 1.06%) in the plasma PL fraction after 50 d of AA feeding. After consuming the high-AA diet, the total red blood cell fatty acid composition was significantly enriched in AA which mainly replaced linoleic acid. These results indicate that dietary AA is incorporated into tissue lipids, but selectively into different tissues and lipid classes. Perhaps more importantly, the results demonstrate that dietary AA does not alter blood lipids or lipoprotein levels or have obvious adverse health effects at this level and duration of feeding.