Effect of an essential fatty acid deficiency on the phospholipid composition in anterior pituitary membranes.

The effects of an essential fatty acid deficient diet were investigated on the phospholipid fatty acids of several membrane fractions of the rat anterior pituitary, the secretion of which is known to be partly dependent on the membrane phospholipidic constituents. In standard dietary conditions, arachidonic acid (20:4n-6) and its elongation product, adrenic acid (22:4n-6), were the two main polyunsaturated fatty acids in all fractions studied. In rats deprived of EFA for 6 weeks after weaning, the levels of both 20:4n-6 and 22:4n-6 were not changed in microsomal + plasma membrane and nuclear fractions, whereas they were decreased in heavy mitochondrial and light mitochondrial fractions. The present data suggest a mechanism of compensation between membrane fractions which may preferentially preserve 20:4n-6 and 22:4n-6 in discrete membrane fractions.     

Sarcolemmal phospholipid fatty acid composition and permeability

In this study, the mechanism of ischaemia-induced increased sarcolemmal permeability, as manifested by release of intracellular enzymes, was investigated. The role of changes in the sarcolemmal phospholipid bilayer in this process was evaluated by experimental modulation of the phospholipid fatty acid composition. The isolated perfused rat heart subjected to low-flow hypoxia, was used as a model of global ischaemia. Glucose as well as saturated (palmitate) and unsaturated (linoleate) long-chain fatty acids were used as substrates. Hearts perfused with palmitate or linoleate (1.5 mM, fatty acid/albumin ratio, 3.4) showed a significantly higher rate of lactate dehydrogenase release in both control and ischaemic conditions than hearts perfused with glucose (10 mM). Lactate dehydrogenase release in the fatty acid-perfused hearts was associated with a significant increase in the percentage unsaturation of the sarcolemmal phospholipid fatty acids. Glucose-perfused hearts, on the other hand, showed only minor changes in the sarcolemmal phospholipid fatty acid composition. Attempts to correlate enzyme release directly with an increase in the percentage unsaturation of phospholipid fatty acids failed, since enzyme release was also stimulated in control fatty-acid-perfused hearts which (when compared with glucose) contained a higher percentage saturated phospholipid fatty acids. The results suggest that myocardial ischaemia, apart from changes in the sarcolemmal phospholipid fatty acid composition, also induces several other changes in sarcolemmal composition (e.g., cholesterol loss) which may affect is permeability for macromolecules.     

Effect of ethanol on the phospholipid and fatty acid content of Schizosaccharomyces pombe membranes

Ethanol at concentrations up to 5% (v/v) had no effect on the growth of Schizosaccharomyces pombe, whereas concentrations over 7.5% were inhibitory. The major membrane phospholipids in S. pombe cells growing aerobically in the absence of added ethanol were phosphatidylinositol, phosphatidylcholine and phosphatidylethanolamine. Oleic acid (18:1) was the main fatty acid. When ethanol (7.5%) was added to aerobically growing cultures, the phosphatidylinositol content increased, whereas the 18:1 content decreased. Similar changes were observed in the membrane phospholipids of cells grown anaerobically without ethanol. However, the presence of ethanol in anaerobically growing cultures had an opposite effect on fatty acids, as the 18:1 content increased. The results support the idea that ethanol tolerance in S. pombe may be connected with a high content of 18:1 fatty acids, and with the ability to maintain a high rate of phospholipid biosynthesis.     

Effect of phospholipid fatty acid composition of endothelial cells on cholesterol efflux rates.

Human endothelial cells (EA.hy 926 line) were loaded with cationized low density lipoprotein (LDL) and subsequently incubated with fatty acid/bovine serum albumin complexes. The fatty acids were palmitic, oleic, linoleic, arachidonic, and eicosapentaenoic acids. The preincubations resulted in extensively modified fatty acid profiles in cell membrane phospholipids and in cellular cholesteryl esters. The cholesterol efflux from these fatty acid-modified cells was measured using 0.2 mg high density lipoprotein3 (HDL3)/ml medium. The efflux was significantly higher for the palmitic acid-treated cells, compared to all other fatty acid treatments. These differences in efflux rates were not caused by changes in the binding of HDL3 to high affinity receptors on the EA.hy 926 cells. Efflux mediated by dimethyl suberimidate-treated HDL3, which does not interact with high affinity HDL receptors, was similar to efflux induced by native HDL3 after all fatty acid treatments. Our results indicate that high affinity HDL receptors are not important for HDL-mediated efflux of cell cholesterol. The fatty acid composition of the cell membrane phospholipids may be an important determinant.     

Effect of exogenous fatty acids on growth,membrane fluidity,and phospholipid fatty acid composition in yeast

The growth response of a double-mutant fatty acid auxotroph of yeast Saccharomyces cerevisiae to exogenous saturated fatty acids of a homologous series from 12:0 to 16:0, each supplied with oleate, linoleate, linolenate, or cis-Δ¹¹- eicosenoate, cannot be explained in terms of the efficiency of incorporation of the fatty acids into phospholipids or alteration of membrane fluidity. There is, however, a negative correlation between growth and levels of 12:0 plus 13:0 in phospholipids, as well as a positive correlation between growth and levels of 14:0, 1 5:0, and 1 6:0. We, therefore, conclude that the predominant factor in these phospholipid fatty acyl chain modifications is maintenance of an optimal concentration of C14:0 through C16:0 in phospholipids of this organism.     

Peculiarities of the phospholipid and fatty acid composition of erythrocyte plasma membranes of the black sea fish

The phospholipid and the fatty acid composition of the main phospholipid families of erythrocyte plasma membranes was studied in two species of cartilaginous fish: the common thrasher (Raja clavata L.) and the common stingray (Dasyatis pastinaca) and in three bony fish species: the scorpion fish (Scorpaena porcus L.), the smarida (Spicara flexuosa Raf.), and the horse mackerel (Trachurus mediterraneus ponticus Aleev). It was shown that in the studied fish, 70.0–80.0% of all membrane phospholipids were composed of phosphatidylcholine and phosphatidylethanolamine. Phosphatidylserine, monophosphoinositide, and sphingomyelin were minor components whose content in the erythrocyte membrane fluctuated from 3.0% to 13.0%. The fatty acid phospholipids composition was represented by a large specter of acids. From saturated acids, basic for plasma membranes are palmitic (C16: 0) and stearic (C18: 0) acids. From unsaturated acids, the larger part belongs to mono-, tetra-, penta-, and hexaenoic acids in fish phospholipids. The calculation of the double bond index and of the unsaturation coefficient showed difference in the deformation ability of erythrocyte membranes of the studied fish.     

Peculiarities of the phospholipid and fatty acid composition of erythrocyte plasma membranes of the Black Sea fish

The phospholipid and the fatty acid composition of the main phospholipids families of erythrocyte plasma membranes was studied in two species of cartilaginous fish: the common thrasher (Raja clavata L.) and the common stingray (Dasyatis pastinaca) and three bony fish species: the scorpion fish (Scorpaena porcus L.), the smarida (Spicara flexuosa Raf.), and the horse mackerel (Trachurus mediterraneus ponticus Aleev). It was shown that in the studied fish, 70.0-80.0 % of all membrane phospholipids were composed of phosphatidylcholine and phosphatidylethanolamine. Phosphatidylserine, monophosphoinositide, and sphingomyelin were minor components whose content in the erythrocyte membrane fluctuated from 3.0 % to 13.0 %. The fatty acid phospholipids composition was represented by a large specter of acids. From saturated acids, basic for plasma membranes are palmitic (C16: 0) and stearic (C18: 0) acids. From unsaturated acids, the larger part belong to mono-, tetra-, penta-, and hexaenoic acids in fish phospholipids. The calculation of the double bond index and of the unsaturation coefficient showed difference in the deformation ability of erythrocyte membranes of the studied fish.     

Effect of membrane fluidity and fatty acid composition on the prothrombin-converting activity of phospholipid vesicles.

Vesicles composed of phospholipids with different fatty acyl side chains have been utilized to examine the importance of the nonpolar membrane region for the prothrombin-converting activity of procoagulant phospholipid vesicles. Membranes composed of phosphatidylserine (PS) and phosphatidylcholine (PC) with unsaturated fatty acyl side chains were more active in prothrombin activation than membranes composed of phospholipids with saturated fatty acyl chains. This phenomenon was observed above the phase transition temperature, i.e., on membranes in the liquid-crystalline state. The prothrombin-converting activity of saturated phospholipids approached the activity of unsaturated phospholipids at high factor Va concentrations, which is indicative for a less favorable equilibrium constant for prothrombinase assembly on membrane surfaces composed of saturated phospholipids. The difference between saturated and unsaturated phospholipids was annulled on membranes with high mole percentages of PS. This may result from a compensating contribution of electrostatic forces to the binding equilibria involved in prothrombinase assembly. Additional effects on the prothrombin-converting activity were observed when membranes containing saturated phospholipids were studied below their phase transition temperature. In agreement with Higgins et al. [(1985) J. Biol. Chem. 260, 3604-3612], we found that the time required for the assembly of prothrombinase from membrane-bound factors Xa and Va is considerably prolonged on solid membranes. However, we also observed an effect of membrane fluidity on the steady-state rate of prothrombin activation. Kinetic experiments at saturating factor Va concentrations showed that the transition from the liquid-crystalline to the gel state caused a more than 9-fold decrease of the kcat of prothrombin activation without affecting the Km for prothrombin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characterization of the phospholipid and fatty acid composition of Sendai virus

The lipid composition of Sendai virus, propagated in chicken eggs, was analyzed by high performance liquid chromatography (HPLC), thin-layer chromatography (TLC), and gas-liquid chromatography (GLC). Phosphatidylcholine was found to be the dominant phospholipid (37.3%) with phosphatidylethanolamine (26.8%) and phosphatidylserine (12.0%) also present in significant amounts. Analysis of the fatty acid methyl esters revealed that the dominant fatty acids in total phospholipid were: C16:0 (17.6%), C18:0 (15.4%), C18:1 (n-9) (22.0%), and C24:0 (6.0%). Cardiolipin, phosphatidylserine, and sphingomyelin contained higher levels of saturated fatty acids relative to phosphatidylinositol, phosphatidylethanolamine, and phosphatidylcholine.     

Specific phospholipid fatty acid composition of brain regions in mice. Effects of n-3 polyunsaturated fatty acid deficiency and phospholipid supplementation

This study examined the effects of dietary alpha-linolenic acid deficiency followed or not by supplementation with phospholipids rich in n;-3 polyunsaturated fatty acid (PUFA) on the fatty acid composition of total phospholipids in 11 brain regions. Three weeks before mating, mice were fed a semisynthetic diet containing both linoleic and alpha-linolenic acid or deficient in alpha-linolenic acid. Pups were fed the same diet as their dams. At the age of 7 weeks, a part of the deficient group were supplemented with n;-3 polyunsaturated fatty acids (PUFA) from either egg yolk or pig brain phospholipids for 2 months. Saturated and monounsaturated fatty acid levels varied among brain regions and were not significantly affected by the diet. In control mice, the level of 22:6 n-3 was significantly higher in the frontal cortex compared to all regions. alpha-Linolenic acid deficiency decreased the level of 22:6 n-3 and was compensated by an increase in 22:5 n-6 in all regions. However, the brain regions were affected differently. After the pituitary gland, the frontal cortex, and the striatum were the most markedly affected with 40% reduction of 22:6 n-3. Supplementation with egg yolk or cerebral phospholipids in deficient mice restored a normal fatty acid composition in brain regions except for the frontal cortex. There was a regional distribution of the fatty acids in the brain and the impact of deficiency in alpha-linolenic acid was region-specific. Dietary egg yolk or cerebral phospholipids are an effective source of n-3 PUFA for the recovery of altered fatty acid composition induced by a diet deficient in n-3 PUFA.     

Training affects muscle phospholipid fatty acid composition in humans.

Training improves insulin sensitivity, which in turn may affect performance by modulation of fuel availability. Insulin action, in turn, has been linked to specific patterns of muscle structural lipids in skeletal muscle. This study investigated whether regular exercise training exerts an effect on the muscle membrane phospholipid fatty acid composition in humans. Seven male subjects performed endurance training of the knee extensors of one leg for 4 wk. The other leg served as a control. Before, after 4 days, and after 4 wk, muscle biopsies were obtained from the vastus lateralis. After 4 wk, the phospholipid fatty acid contents of oleic acid 18:1(n-9) and docosahexaenoic acid 22:6(n-3) were significantly higher in the trained (10.9 +/- 0.5% and 3.2 +/- 0.4% of total fatty acids, respectively) than the untrained leg (8.8 +/- 0.5% and 2.6 +/- 0.4%, P < 0.05). The ratio between n-6 and n-3 fatty acids was significantly lower in the trained (11.1 +/- 0.9) than the untrained leg (13.1 +/- 1.2, P < 0.05). In contrast, training did not affect muscle triacylglycerol fatty acid composition. Citrate synthase activity was increased by 17% in the trained compared with the untrained leg (P < 0.05). In this model, diet plays a minimal role, as the influence of dietary intake is similar on both legs. Regular exercise training per se influences the phospholipid fatty acid composition of muscle membranes but has no effect on the composition of fatty acids stored in triacylglycerols within the muscle.     

Effects of pesticides on the fatty acid and phospholipid composition of Escherichia coli.

Cells of Escherichia coli contained an altered phospholipid and fatty acid composition when grown in the presence of some pesticides. Whereas parathion increased the concentration of all phospholipid species without changes in their polar head groups. DDT (dichlorodiphenyltrichloroethane) decreased the proportion of neutral serine-derived phosphatides and dieldrin decreased the proportion of negatively charged phospholipids. The saturated/unsaturated plus cyclopropane fatty acid ratio was increased in all cases. The changes suggested that cells adapted their membrane lipids to compensate for the presence of pesticides in the environment.     

Subgrouping of bacterial populations by cellular fatty acid composition

Abstract The cellular fatty acid composition of six bacterial species isolated from the seeds and leaves of sugar beet ( Beta vulgaris ) and from soil were analysed. The quantitative data from the fatty acid methyl ester (FAME) profiles were highly reproducible. Numerical analysis of Xanthomonas maltophilia . FAME profiles sub-grouped strains according to when they were isolated in the growing season. The analytical method used was sensitive enough to differentiate strains of Klebsiella terrigena isolated from either soil or leaves. The results from this study confirm reports that analyses of bacterial FAME composition were rapid to perform, specific and allowed differentiation of strains within the same species.     

Effect of benzyl viologen on the phospholipid fatty acid composition and some properties in hepatic microsomal membrane of rats

The effect of benzyl viologen (a stimulator of free radical production in cells) on lipid composition, fluidity and enzymes involved in both polyunsaturated fatty acid biosynthesis and cholesterol metabolism was studied in liver microsomal membrane of adult rats. In viologen-treated animals, a significant decrease in the levels of free cholesterol and cholesteryl esters, accompanied to a decrease at the free cholesterol/phospholipid ratio, were observed. The levels of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and acyl-coenzyme A : cholesterol acyltransferase (ACAT) were also lower in viologen-treated rats than in controls. Linoleic and arachidonic acids were both severely lower while docosatetraenoic, docosapentaenoic and docosahexaenoic acids were significantly higher as compared with controls. Furthermore, a decrease in monounsaturated/saturated ratio was found. In addition, the treatment evoked a depression in the fatty acid desaturation complex, with a diminish of ⁹, ⁹, and ⁵ desaturase activities in microsomal membrane.It was concluded that changes in phospholipid microsomal fatty acid and cholesterol content could be directly responsible for changes in membrane fluidity and function, and that extensive yield of docosahexaenoic acid may serve to maintain the physical characteristics of particular domains against oxidative stress caused by benzyl viologen treatment.     

Influence of N-palmitoylethanolamine on the phospholipid and fatty acid composition of rat liver in ischemia

The effect of N-palmitoylethanolamine (NPE, 10(-5) M) on the lipid peroxidation (LPO) processes, phospholipid and fatty acid content in the rat liver at perfusion and ischemia during the liver preservation was estimated. As early as at the 5th min of perfusion by cooled conserving solution "Eurocollins", LPO activation was determined. Simultaneously the content of lysophosphatidylcholine (LPC) and phosphatidylserine increased, the total cholesterol level decreased. The redistribution of saturated and unsaturated fatty acids quantity was detected. The addition of NPE into "Eurocollins" solution reduced the accumulation of malonedialdehyde and LPC, modified the fatty acids content. These effects, evidently, formed the basis of the protective action of NPE on the hepatic tissues under anoxia.     

Relationships between heat resistance and phospholipid fatty acid composition of Vibrio parahaemolyticus.

Vibrio parahaemolyticus was grown in tryptic soy broth (TSB) containing NaCl levels of 0.5, 3.0, and 7.5% (wt/vol). Cultures incubated at 21, 29, and 37 C were harvested in late exponential phases and thermal death times at 47 C (D47 c; time at 47 C required to reduce the viable population by 90%) were determined in phosphate buffer containing 0.5, 3.0, and 7.5% NaCl. At a given NaCl concentration in the growth medium, D47 c values increased with elevated incubation temperatures and with elevated levels of NaCl in the heating menstrua. Differences in thermal resistance of cells cultured at a particular temperature were greater between those grown in TSB containing 0.5 and 3.0% NaCl than between those grown in TSB containing 3.0 and 7.5% NaCl. D47c values ranged from 0.8 min (grown at 21 C in TSB with 0.5% NaCl) to 6.5 min (grown at 37 C in TSB with 7.5%, heated in 7.5% NaCl buffer). Methyl esters of major phospholipid fatty acids extracted from cells were quantitated. The ratio of saturated to unsaturated fatty acids in cells grown at a given NaCl concentration increased with elevated incubation temperature. At a particular growth temperature, however, saturated to unsaturated fatty acids ratios were lowest for cells grown in TSB containing 3.0% NaCl.