Stereospecific analysis of glycerolipids of egg yolk of Japanese quail (Coturnix coturnix japonica)

Phosphatidylcholine, phosphatidylethanolamine and triacylglycerol were isolated from egg yolk of the Japanese quail. Fatty acid compositions at the two and three positions of glycerol in the glycerolipids were determined by stereospecific analysis employing phospholipase A₂. The distribution of the total number of carbon atoms in the fatty acid moieties of triacylglycerol was also quantitated by high temperature gas liquid chromatography. The distribution of acyl groups in each of the positions of the phosphatidylcholine, phosphatidylethanolamine and triacylglycerol was not random, and each position has a characteristic composition. The phosphatidylcholine and phosphatidylethanolamine had distinctive fatty acid distributions for positionsn-2 of the triacylglycerol had a predominance of unsaturated fatty acids of which 18∶1 (69.9%) was the major component. Positionsn-3 contained 49.3% saturated fatty acids and was more saturated than positionsn-1 by 8.1%. The experimentally determined distribution of the carbon numbers in triacyl glycerol deviated significantly from the distribution predicted by 1-random-2-random-3-random association of the fatty acids. The data suggest that in Japanese quail there is marked preferencial synthesis of some triacylglycerols.     

Hepatoma,host liver,and normal rat liver phospholipids as affected by diet

Individual phospholipid classes derived from hepatoma, host liver, and normal liver of rats maintained on chow and fat free diets were examined in detail and the sphingomyelin and phosphoglyceride structures compared. The concentration of hepatoma spingomyelin was higher while phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and diphosphatidylglycerol were only one-fourth to one-half normal liver concentrations, irrespective of diet. Hepatoma phosphatidylcholine, phosphatidylethanolamine, phosphatidyl-serine, and phosphatidylinositol contained higher percentages of 18:1 and, except phosphatidylinositol, much lower percentages of most polyunsaturated fatty acids than liver. The 1-position of host liver phosphatidylcholine and phosphatidylethanolamine, normal liver phosphatidylcholine and phosphatidylethanolamine, and hepatoma phosphatidylcholine from animals on both diets had the same approximate fatty acid composition, but the percentage of 16:0 in hepatoma phosphatidylethanolamine was reduced dramatically. The low percentage of 16:0 at the 1-position of both phosphatidylethanolamine and triglycerides suggests that the 1-position fatty acids of these two classes may have a similar origin. The fat free diet reduced the percentage of 18:2 in liver diphosphatidylglycerol 3-fold and the decrease was offset by increased percentages of 16:1 and 18:1; whereas the very low percentage of 18:2 in hepatoma diphosphatidylglycerol was offset by increased percentages of 18:0 and 16:0. Liver phosphatidylinositol and phosphatidylcholine from the animals fed the fat free diet contained the highest percentage of 20:3, which replaced 20:4. Hepatoma sphingomyelin contained a much higher concentration of 24:0 and 24:1 than liver. The hepatoma sphingomyelin also contained a C-24 dienoic acid, which was not detected in host and normal liver. Host liver contained a higher percentage of 22:6 than normal liver. The diglycerides derived from host liver PC contained a significantly higher percentage of carbon number 38 than normal liver. Diglycerides derived from hepatoma phosphatidylcholine and phosphatidylethanolamine exhibited a 1-random-2-random distribution of fatty acids, whereas diglycerides from liver phosphatidylcholine and phosphatidylethanolamine showed pairing of specific fatty acids.     

The lipid composition of microsomal preparations from lactating bovine mammary tissue

The microsomes isolated from lactating bovine mammary tissue contained 4.3 mg lipid per milligram nitrogen. Phospholipids comprised 83% of the lipids. The neutral lipids were composed of triglycerides (20–30%), diglycerides (5–10%), free fatty acids (15–30%, cholesterol (35–40% and cholesterol esters (10–12%, respectively. Phosphatidylcholine was the predominant phospholipid component (>50%), and the remainder consisted of phosphatidylethanolamine (21–13%), phosphatidylserine (4–6%), phosphatidylinositol (8%), sphingomyelin (9%) and lysophosphatidylcholine (2%) respectively. The composition of the microsomal phospholipids was similar to that of isolated mammary cells and tissue homogenates but quite different from milk and fat globule membrane phospholipids. The triglycerides contained short chain fatty acids but their relative concentrations were lower than in milk triglycerides. The various lipid fractions had a variable proportion of saturated fatty acids, i.e., triglycerides (47.7%), diglycerides (86.7%), free fatty acids (70.6%), phosphatidylcholine (50.6%), phosphatidylethanolamine (50.8%), phosphatidylserine (35.3%), phosphatidylinositol (40.5%) and sphingomyelin (82.3%), respectively. The molecular distribution of fatty acids in the microsomal triglycerides and phosphatidylcholine was similar to that occurring in milk, i.e., the short chain and unsaturated fatty acids were concentrated in the primary positions (sn1 andsn3) of the triglycerides, and the unsaturated acids were preferentially located in positionsn2 of the phosphatidylcholine. The compositional data indicate that mammary microsomes are not the direct source of the phospholipids of the milk fat globule.     

Lipids of cultured hepatoma cells: VIII. Utilization of D-[1-14C] glucose for lipid biosynthesis

Minimal deviation hepatoma 7288C cells (HTC) were incubated in serum-supplemented and serum-free Swim’s 77 medium in the presence of D-[1-¹⁴C] glucose for 1, 2, 4, 8, 12 and 24 hr. Glucose oxidation to CO₂, incorporation into total cell mass, and incorporation into cell and medium lipids were determined. The percentage distribution of total cell lipid radioactivity in individual neutral and polar lipid classes was followed as a function of time. Degradation studies of individual lipid classes were performed to ascertain the percentage of radioactivity in acyl and glycerol moieties. The percentage of D-[1-¹⁴C] glucose oxidized to¹⁴CO₂, incorporated into cell matter and cell lipids was elevated in cells incubated in serum-free medium as opposed to serum-supplemented medium. The percentage distribution of total cell lipid radioactivity into individual neutral lipid classes from both serum-free and serum-supplemented cultures was as follows: sterols > triglycerides > free fatty acids > sterol esters. The percentage distribution of total cell lipid radioactivity into individual polar lipid classes of serum-supplemented cultures was as follows: phosphatidylcholine > phosphatidylinositol > sphingomyelin > phosphatidylethanolamine > phosphatidylserine. The distribution of glucose radiolabel into individual polar lipid classes of serum-free HTC cells was different from their serum-supplemented counterparts: sphingomyelin > phosphatidylcholine > phosphatidylinositol > phosphatidylethanolamine > phosphatidylserine. Glycerol from glyceride classes contained a higher percentage of radioactivity than the acyl moieties, with this percentage significantly elevated in serum-free cultures. The data indicate that, although glucose is a substrate for HTC cell lipids, other precursors present in the culture system also contribute to the lipid constituency of this hepatoma cell line.     

The structures of the principal glycerolipids of pig liver

The lipid composition of pig liver has been determined. The principal glycerolipids, i.e., triglycerides, phosphatdyl choline, phosphatidyl ethanolamine and phosphatidyl inositol, were isolated and the positional distribution of fatty acids in each determined by stereospecific analysis procedures. Previous results for the triglycerides were confirmed, while the phospholipids were similar in structure to those found in most other animal livers. The triglycerides were separated into simpler molecular species by combinations of silver nitrate thin layer chromatography and high temperature gas liquid chromatography, but the proportions found did not agree well with those calculated assuming a 1-random, 2-random, 3-random arrangement. The phospholipids were hydrolyzed with phospholipase C and converted to diglyceride acetates that were fractionated into simpler molecular species by the same procedures as were used with triglycerides. Highly specific fatty acid combinations were found in molecular species, and these specificities were very similar to those reported in similar lipids from the livers of such disparate species as the rat and chicken.     

Lipids of cultured hepatoma cells: III. Triglyceride and phosphoglyceride biosynthesis in minimal deviation hepatoma 7288C

Minimal deviation hepatoma 7288 C cells were cultured on media containing 25% serum to the confluent stage. The growth media was replaced with serumfree media containing 1-¹⁴C-palmitate, and incubations were continued for 0.75, 1.5, 3, 6, 12, and 24 hr. The distribution of radioactivity among the major neutral lipids and phosphoglycerides was determined for cells and culture media. Radioactivity in individual fatty acids of cellular triglyceride, phosphatidylcholine, and phosphatidylethanolamine also was determined. After 24 hr, more than 95% of the administered radioactivity was recovered in neutral and phosphoglycerides, indicating that only a small amount of the fatty acid was oxidized. At any time period examined, over 80% of the incorporated radioactivity was found in triglyceride, phosphatidylcholine, and phosphatidylethanolamine. Incorporation of the label into cellular triglyceride and phosphatidylcholine plateaued at 12 hr, whereas incorporation of radioactivity into phosphatidylethanolamine still was increasing at 24 hr. In contrast, during the entire incubation period the relative distribution of¹⁴C among esterified lipid classes in the culture media remained constant. Elongation of palmitic acid to stearic acid and its subsequent desaturation to oleic acid suggests that these cells possess an active elongation and monoenoic desaturation system. Labeled glycerol ether diesters were not detected in the cells or culture media. Positional distribution of the¹⁴C label in the triglyceride and phosphatidylcholine suggests that minimal deviation hepatoma cells do not exhibit diglyceride selectivity in the biosynthesis of these two lipid classes.     

The structural analysis of wheat flour glycerolipids

The compositions of the fatty acids in the 1, 2 and 3 positions of the principal glycerolipids and their various stereoisomers were determined. Fatty acids in the 1 and 3 positions of triglycerides were similar in composition and less unsaturated than those in the 2 position. Fatty acids in the 1,2-, 1,3- and 2,3-diglycerides were distributed in a pattern which indicated isomerization ofsn-1,2-diacylglycerol. Lysophosphatidyl choline (the principal monoacyl lipid) consisted of about 80% 1-acyl and 20% 2-acyl isomers. The fatty acid compositions indicated that most of the 2-lysophosphatidyl choline was formed by isomerization of 1-lysophosphatidyl choline. Most of the digly cerides and lysophosphatidyl choline were synthesized in the ripening wheat grain. However a small proportion of these partial glycerides and all of the other minor partial glycerides (monoglycerides, digalactosyl monoglycerides) appeared to be the result of limited lipolysis of the corresponding diacyl lipids in the wheat or in the freshly-milled flour. Fatty acids in the 2 position of all the fully acylated glycerides were very similar in composition, but there were considerable differences in the 1 position fatty acids.     

Lipids of cultured hepatoma cells: IV. Effect of serum and lipid upon cellular and media neutral lipids

Minimal deviation hepatoma 7288C cells were cultured in a modified Swim's medium supplemented with decreasing levels of serum, lipid-free serum, lipid-free serum plus fatty acids, and other additives. Cellular and media neutral lipid classes were quantitated, the fatty acids of triglycerides and sterol esters analyzed, and the carbon number distribution of triglycerides determined. Cellular triglyceride biosynthesis virtually was inhibited when the medium was supplemented with bovine serum alone. This inhibition was not observed when the medium was supplemented with fetal calf serum alone or mixtures of fetal calf serum and bovine serum. Cells cultivated on medium supplemented with lipid-free serum plus palmitic or linoleic acids had much lower levels of free and esterified cholesterol. The fatty acid composition of cellular triglycerides and cholesterol esters differed dramatically from the corresponding media lipid classes. Except when linoleic acid was added to the medium, changes in the media serum and lipid levels had only marginal effects upon the fatty acid composition of cellular triglycerides and cholesterol esters. These data, in conjunction with earlier data that showed the media neutral lipid levels did not decrease during cell growth, indicate that these hepatoma cells utilize little or no serum triglycerides and cholesterol esters. Linoleic acid added to the medium dramatically reduced the level of 18∶1 acids in cellular triglycerides and cholesterol esters. Palmitic acid added to the medium did not change the fatty acid compositions significantly. Comparison of experimentally determined and calculated triglyceride carbon number percentages indicated a random distribution of fatty acids in this glyceride. The fatty acid composition of cellular triglycerides was similar to the composition of the cholesterol esters. The lack of characteristic and distinguishable compositions of these two classes that occur in most normal tissues suggests a loss of specificity in the lipid metabolism of this neoplasm at the class level.     

Etherlipide als Substrate zur Untersuchung der Spezifität von Enzymen der Glycerolipid-Biosynthese in höheren Pflanzen

Ether Lipids as Substrates for Studying the Specificity of Enzymes Involved in Glycerolipid Biosynthesis of Higher Plants Ether glycerolipids, predominantly alkylacylglycerols and alkylacylglycerophosphocholines, are synthesized in photomixotrophic rape (Brassica napus) suspension cells from various exogenous monoalkylglycerols. The stereospecific distribution of acyl moieties in these ether glycerolipids was studied with regard to chain-length and degree of unsaturation of alkyl moieties and compared with the distribution of acyl moieties in the corresponding endogenous acyl glycerolipids. The results show the following: (a) Alkylacylglycerophosphocholines replaced up to one-half of the corresponding physiological membrane lipids, i.e. diacylglycerophosphocholines, without changing the total amount of cholineglycerophospholipids as compared to untreated cells. (b) The composition of acyl moieties in total lipids of rape cells was practically not altered by fatty acids derived via oxidative cleavage from the various alkyl moieties of ether glycerolipids. (c) In 1–0-alkyl-2-acylglycerols derived from exogenous alkylglycerols and in endogenous 1,2-dinacylglycerols compositions of acyl moieties were found to be different indicating that different pathways were operative in the biosynthesis of these two neutral glycerolipids. (d) Enzymes involved in synthesizing molecular species of 1–0-alkyl-2-acyl or 2–0-alkyl-1-acylglycerophosphocholines as well as 1,2-diacylglycerophosphocholines showed similar specificities with regard to chain-length and degree of unsaturation of both, alkyl and corresponding acyl moieties. Thus, ether glycerolipids formed by plant cells from exogenous alkylglycerols are metabolites suitable for studying the specificity of enzymes involved in the biosynthesis of glycerolipids.     

Analytik plasmalogenhaltiger Phosphatide aus Herzgewebe mittels extracellulärer Phospholipase A2

The Analysis of Phospholipids from Cardiac Membranes by Phospholipase A₂. Phospholipase A₂ from snake venom has been employed to analyse the positional distribution of fatty acids in glycerolipids from guinea pig and pig cardiac membranes. It is known that phospholipase A₂ hydrolyses the fatty acids in sn-2 position of 1,2 diacylglycerophospholipids. In cardiac membranes phosphatidylcholine and phosphatidylethanolamine contain along with diacyl esters the corresponding alkenylether analogues of phospholipids. In the present experiments the alkenylether moieties were slowly hydrolysed by phospholipase A₂ from snake venom. We therefore separated by TLC lysophosphatides from fatty acids and unattacked phospholipids. The latter were the plasmalogens. The separated lipids were characterized by GLC. In some experiments the phospholipids were labelled with ¹⁴C-fatty acids before they were hydrolysed by phospholipase A₂. The alkenyl ether chain of plasmalogens seems to negativly influence the hydrolysis of fatty acids in sn-2 position of those phospholipids.     

Distribution of long chain polyenoic acids among phospholipids of mouse testis

Fatty acid composition of phospholipid (PL) classes was measured in mouse testis. Among the long-chain polyenoic acids (LCPA), 22∶6 was found in highest concentration in phosphatidylethanolamine (PE), whereas percentages of 20∶4 and 22∶5 were not different in PE than in phosphatidylcholine. Each PL class had a unique fatty acid composition which was also different from that of triglycerides and cholesteryl esters. Differential metabolisms of 22∶5 and 22∶6 suggest different roles for these fatty acids in mouse testis. Tissue-specific functions of LCPA in mouse spermatogenesis may be divided between 22∶5 and 22∶6.     

Glycerides ofLimnanthes douglasii seed oil

Brockerhoff-type procedures were used to determine the amounts of each acyl group at each glyceride position ofLimnanthes douglasii seed oil. During the course of the analyses, small quantities of three acids isomeric with those previously found in the oil were identified by their ozonolysis products and their gas-liquid chromatographic (GLC) behavior. The newly discovered constituents of the oil were 3-octadecenoic acid (0.1%), 5-octadecenoic acid (0.9%) and 11-eicosenoic acid (3%). The saturated acids and those with ω-9-unsaturation are esterified most often to β-glyceride positions inLimnanthes seed, while the acids with Δ5-unsaturation occur generally at the outer glyceride positions. Although the Δ5-unsaturated acids as a group exhibited no obvious preference for one outer position over the other, individual acids were unequally distributed between the 1- and 3-sn-glycerol positions. The probabilities of occurrence of the various triglycerides were calculated from the stereospecific analysis data by assuming a 1-random, 2-random, 3-random distribution of the acyl groups. The calculations are in agreement with the composition of the whole oil, as determined by GLC. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Fatty acid and molecular species composition of rat brain phosphatidylcholine and-ethanolamine from birth to weaning

The fatty acid composition of diacyl phosphatidylcholine and phosphatidylethanolamine from the brain of rats 3, 6, 9, 12, 15, 18, and 21 days old were determined. In phosphatidylcholine, the relative amounts of stearic and oleic acid increased from 25% to 33% while the relative amounts of myristic, palmitic, and palmitoleic decreased from 65% to 50% during this time period. The same pattern was seen in phosphatidylethanolamine with stearic and oleic increasing from 38% to 49% and the shorter chain acids decreasing from 17% to 13%. The polyunsaturated fatty content of phosphatidylcholine was approximately 10% and increased slightly during the first 3 weeks, while the polyunsaturated content of phosphatidylethanolamine decreased from 44% to 37%. The molecular species composition of phosphatidylcholine and phosphatidylethanolamine was determined in brains of rats 3, 6, and 9 days old. The relative amounts of the molecular species remained nearly constant during this time period with phosphatidylcholine containing 35% saturated, 40% monoenoic, 6% dienoic, 11% tetraenoic, 2% pentaenoic, and 5% hexaenoic. Phosphatidylethanolamine contained 1% saturated, 8% monoenoic, 3% dienoic, 40% tetraenoic, 9% pentaenoic, and 37% hexaenoic species. Analysis of the fatty acid composition of the molecular species reveals that in phosphatidylcholine the polyunsaturated fatty acids 20∶4 and 22∶6 are predominately paired with 16∶0, while in the phosphatidylethanolamine these two unsaturated fatty acids are paired with 18∶0. Furthermore, dipalmitoyl phosphatidylcholine accounts for approximately 25% of the total molecular species of that lipid.     

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).     

The Saturated sn-2-Triglycerides of Palm-Kernel Oil

The saturated sn-2-triglycerides (the fatty acid esterified at the 2-position is known) of palm-kernel oil, representing 78%, was isolated by argentation thin-layer chromatography. The nine groups of this fraction (triglycerides with the same total acyl carbon atoms) were fractionated by gas-liquid chromatography and their component fatty acids determined. From the fatty acid composition of each group it was possible to determine mathematically the component triglyceride types of the group (the 3 fatty acids are known, but their positional distribution is not). The proportion of 46 types were calculated in this way. The major fractionate groups (6 out of 9) were hydrolyzed by pancreatic lipase. From the component 2-mono-glycerides it was possible to determine the proportion of 44 sn-2-triglycerides which account for 75% of the oil triglycerides. Trilaurin (21%) is the major component, followed by sn-2-lauro-1,3-lauromyristin (12%). These two triglycerides together form one third of the glyceride content of the oil. Sn-2-lauro-1,3-caprylolaurin (7%), 5 sn-2-triglycerides (2 to 5%), 9 (1 to 2%) were also found, and 27 triglycerides present at less than 1%. The calculated 1,3-random-2-random distribution of fatty acids on glycerol molecules exhibited great differences from the experimentally determined distribution. Consequently, calculations of this kind cannot replace a complete analytical analysis of palm-kernel oil such as the one reported in this work.     

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.     

Incorporation of arachidonic acid and eicosapentaenoic acid into phospholipids by polymorphonuclear leukocytes in vitro

The present study demonstrated that the patterns of the incorporation of [1-¹⁴C] arachidonic acid and [1-¹⁴C] eicosapentaenoic acid into individual phospholipids by polymorphonuclear leukocytes were similar. However, human leukocytes exhibited higher activity than guinea pig periotoneal leukocytes in the formation of arachidonoyl- and eicosapentaenoyl-phosphatidic acid. Cells from both origins showed a decrease of label in phosphatidylcholine accompanied by an increase of label in phosphatidylethanolamine after a longer period (30–120 min) of incubation, suggesting that part of the arachidonoyl or eicosapentaenoyl moiety in phosphatidylethanolamine may be derived from that of phosphatidylcholine. The observed difference between human cells and elicited cells in the time-course of the incorporation of both fatty acids into phosphatidylcholine and phosphatidylethanolamine appears to be due to different contents of the diacyl and ether-linked class compositions of these phospholipids in cells from different origins. Both labeled fatty acids were incorporated more rapidly into the diacyl-linked class, but were retained to a greater extent in alkylacyl-phosphatidyl-choline and alkenylacyl-phosphatidylethanolamine. The data suggest that, in addition to alkylacyl-phosphatidylcholine and phosphatidylinositol, alkenylacyl-phosphatidylethanolamine may be an important endogenous source of arachidonic acid and eicosapentaenoic acid in stimulated human leukocytes.     

Unusual lipids II: Head oil of the north Atlantic pilot whale,Globicephala melaena melaena

Pilot whale head oil (blackfish head oil, raw) was analyzed by means of IR spectroscopy, NMR, thin layer chromatography, and gas liquid chromatography-mass spectrometry. The oil consisted of hydrocarbons (mainly pristane) (3%); waxes and cholesterol esters (9%); triglycerides (87%) (i.e. non-11%, mono-19% and di-57% isovalero triglycerides) and cholesterol and diglycerides (1%). By mass spectrometry, the diisovalero triglycerides were shown to be mainly symmetrical. Fatty acids were isobranched or normal (only traces of anteiso acids were found), saturated, or monounsaturated. Isovaleric acid predominated (54 mole % fatty acids), the rest having 10–18 carbon atoms. A 5-carbon fatty acid was the only acid found in the waxes. The alcohol composition qualitatively resembled that of the fatty acids, but major quantitative differences were present. This rules out direct interconversion of all fatty acids and alcohols. The possible role of these lipids in ultrasound transmission is discussed.     

Continuous supercritical carbon dioxide processing of palm oil

Crude palm oil was processed by continuous supercritical carbon dioxide. The process reduces the contents of free fatty acids, monoglycerides and diglycerides, certain triglycerides, and some carotenes. The refined palm oil from the process has less than 0.1% free fatty acids, higher carotene content, and low diglycerides. Solubility of palm oil in supercritical carbon dioxide increased with pressure. A co-solvent improves the refining process of palm oil.     

Quantitative31P nuclear magnetic resonance analysis of the phospholipids of erythrocyte membranes using detergent

³¹P Nuclear magnetic resonance (NMR) spectra of human erythrocyte lysates dissolved in sodium cholate were acquired. The narrow resonances of phospholipids were mostly well resolved, allowing identification and accurate quantitative analysis of phospholipid classes of the erythrocyte membranes. The ether-linked phosphatidylethanolamine components of the erythrocyte membranes were identified, based on the removal of plasmalogens by acidolysis and of diacyl phospholipid species by degradation using phospholipase A₁. It was also shown that the introduction of double bonds on the acyl chains of phosphatidylcholine shifted the³¹P NMR resonances to lower frequencies. Quantitative analyses of phospholipids from the spectra were based on their apparent molar concentrations. The recoveries of phospholipids from erythrocytes were significantly higher than those using conventional extraction procedures.