Free-radical oxidation of biological membrane lipids. VI. Nature of linoleic acid chemiluminescence]

An original scheme of chemoluminescence of unsaturated fat acids is suggested on the basis of analysing the kinetics of peroxide formation, chemoluminescence and fluorescence of linole acid. The agreement of the model with literature and our own experimental data is shown by the method of analogue modelling.     

Neutral lipids, phospholipids and higher fatty acids in bull's testes

The lipid fractions were studied in the testicular tissue of mature bulls, of the lowland black-and-white breed. It was found that the main component of neutral lipids was cholesterol (48%) followed by triglycerides (24%), cholesterol esters (16%) and free fatty acids (12%). In cholesterol esters the main component was palmitic acid (41%) followed by oleic acid (22%), stearic acid (14%) and linoleic acid (14%). In phospholipids the main fraction was composed of lecithins (48%) followed by phosphatidylethanolamine (20%) and phosphatidic acids and phosphatidylglycerol (13%). Palmitic acid was found mainly in the fractions of lecithins and sphingomyelins, stearic acid in fractions of phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol. Linoleic acid was found in the fractions of phosphatidylethanolamine, phosphatidylcholine and sphingomyelin. Arachidonic, docosatetraenoic and docosapentaenoic acids in the fractions of phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol and phosphatidylcholine.     

Free radical oxidation of biological membrane lipids. VII. Effect of ultraviolet radiation on free radical oxidation of lipids complexed with protein and in biomembranes]

Promoting effect of protein component on the development of free radical oxidation in the systems ethylarahidonate--bovine serum albumin and mitochondria suspension under UV irradiation has been shown. Connection between the processes of peroxide formation and the change of the functional activity of organells has been followed.     

Effect of alpha-tocopherol and phospholipids with omega-3 fatty acids on membrane properties

As a result of the investigations conducted it was displayed, that alpha-tocopherol and phospholipids including into their composition omega-3-acids, differed in their influencing the composition of heart microsomes membranes lipids. The insufficient quantity of vitamin E in the animals ration was defined as leading to the cardiac microsomes lisophospholipids (lisophosphatidylcholin, lisophospatidylethanolamin), diphosphatidylglycerol increase as well as to the tendency to sphingomyeline and phosphatidylethanolamin decrease. While administrating both alpha-tocopherol and the complex of phospholipids with omega-3-fatty acids, the correction of the phospholipids composition microsomes membranes is observed as tending towards their stabilization, however the marine phospholipids complex is more active than alpha-tocopherol. Administration of phospholipids with omega-3-fatty acids during the period of 30 days provided for the increase of relationship: polyunsaturated fatty acids to saturated fatty acids in the cardiac microsomal membranes, evidencing about increasing the unsaturated cellular membranes. While administrating the phospholipids, into the cardiac microsomes the eicozepentaenic acid was identified, failing to be in the norm, docozahexaenic acid content increased. The results obtained testify, that at the pathology there are changes in the quantitative relationship of membrane phospholipids and fatty acids, being a result of changing the biomembranes permeability as well as their functions disturbances. The adverse effect of E-deficiency to the membrane structure was revealed as capable to be regulated by the marine phospholipid complex, including omega-3-fatty acids.     

Polyunsaturated fatty acids in plasma and erythrocyte membrane lipids of diabetic children

While insulin is a potent activator of essential fatty acid metabolism, portal hypoinsulinemia is common in Type 1 diabetes. Fatty acids were determined by high-resolution capillary gas-liquid chromatography in plasma and erythrocyte membrane lipids in diabetic children (n = 40) and in age-matched healthy controls (n = 40). In plasma phospholipids, values of linoleic acid (23.00 [2.35] vs. 18.13 [2.54], % by wt, median [range from the first to the third quartile], P<0.000l) and alpha-linolenic acid (0.12 [0.06] vs. 0.07 [0.07], P<0.05) were significantly higher in diabetic children than in controls. In contrast, values of arachidonic acid (10.73 [2.34] vs. 11.53 [2.50], P<0.05) and docosahexaenoic acid (2.23 [0.63] vs. 2.77 [0.98], P<0.01) were significantly lower in diabetic children than in controls. Reduced availability of long-chain polyunsaturates in diabetic children suggests that an enhanced dietary supply of long-chain polyunsaturates may be beneficial.     

Positional distribution of fatty acids in the phospholipids of regenerating rat liver]

The fatty acid composition and positioning in the glycerophospholipids from regenerating rat liver were investigated at different stages of the regeneration process. In the lecithins and phosphatidylethanolamines of the regenerating liver the content of arachidonic acid is lower and that of linoleic acid is higher than in the corresponding lipid fractions of normal rat liver. These deviations are maximal at 24 hours after hepatectomy i.e. at the onset of the mitosis. At any stage of the regeneration the high specifity of the fatty acid positioning characteristical for the normal liver is retained completely. The fatty acid composition of cardiolipin is not changed during the regeneration process.     

Effects of ethanol on the incorporation of free fatty acids into cerebral membrane phospholipids

Chronic ethanol exposure is known to affect deacylation-reacylation of membrane phospholipids (PL). In our earlier studies we have demonstrated that chronic exposure to ethanol (EtOH) leads to a progressive increase in membrane phospholipase A2 (PLA2) activity. In the current study, we investigated the effects of chronic EtOH exposure on the incorporation of different free fatty acids (FFAs) into membrane PL. The results suggest that the incorporation of fatty acids into four major PL varied from 9.6 fmol/min/mg protein for docosahexaenoic acid (DHA) into phosphatidylinositol (PI) to 795.8 fmol/min/mg protein for linoleic acid (LA) into phosphatidylcholine (PC). These results also suggest a preferential incorporation of DHA into PC; arachidonic acid (AA) into PI; oleic acid into phosphatidylethanolamine (PE) and PC; LA into PC and stearic acid into PE. Chronic EtOH exposure affected the incorporation of unsaturated fatty acid into PI, phosphatidylserine (PS) and PC. However, EtOH did not affect significantly the incorporation of any of the fatty acids (FA) studied into PE. No significant differences were observed with the stearic acid. It is suggested that acyltransferases may play an important role in the membrane adaptation to the injurious effects of EtOH.     

FadD is required for utilization of endogenous fatty acids released from membrane lipids

FadD is an acyl coenzyme A (CoA) synthetase responsible for the activation of exogenous long-chain fatty acids (LCFA) into acyl-CoAs. Mutation of fadD in the symbiotic nitrogen-fixing bacterium Sinorhizobium meliloti promotes swarming motility and leads to defects in nodulation of alfalfa plants. In this study, we found that S. meliloti fadD mutants accumulated a mixture of free fatty acids during the stationary phase of growth. The composition of the free fatty acid pool and the results obtained after specific labeling of esterified fatty acids with a Δ5-desaturase (Δ5-Des) were in agreement with membrane phospholipids being the origin of the released fatty acids. Escherichia coli fadD mutants also accumulated free fatty acids released from membrane lipids in the stationary phase. This phenomenon did not occur in a mutant of E. coli with a deficient FadL fatty acid transporter, suggesting that the accumulation of fatty acids in fadD mutants occurs inside the cell. Our results indicate that, besides the activation of exogenous LCFA, in bacteria FadD plays a major role in the activation of endogenous fatty acids released from membrane lipids. Furthermore, expression analysis performed with S. meliloti revealed that a functional FadD is required for the upregulation of genes involved in fatty acid degradation and suggested that in the wild-type strain, the fatty acids released from membrane lipids are degraded by β-oxidation in the stationary phase of growth.     

Incorporation of specific exogenous fatty acids into membrane lipids modulates protonophore resistance in Bacillus subtilis.

Attempts to manipulate the level of C16:1 fatty acids in membrane phospholipids were made by using Bacillus subtilis and its protonophore-resistant mutants to test the hypothesis that C16:1 fatty acid levels relate to the bioenergetic properties of the mutant strains. Growth of the three mutants in the presence of palmitoleic acid restored the level of C16:1 fatty acids in the membrane lipids to somewhat above those found in the wild type. The palmitoleic acid was preferentially incorporated into diphosphatidylglycerol (cardiolipin) and phosphatidylethanolamine and was associated with increased levels of these phospholipids. These membrane preparations showed no increase in the levels of free fatty acids. The increase in C16:1 fatty acids achieved by growth in the presence of palmitoleic acid was accompanied by secondary changes in membrane lipids as well as a pronounced diminution in the protonophore resistance of growth and ATP synthesis. Other membrane-associated properties that had been observed in these mutants, e.g., elevated ATPase levels, were not altered coordinately with protonophore resistance and C16:1 fatty acid levels. Growth of the wild type in the presence of palmitic acid caused a modest elevation of the C16:0 of the membrane lipids and a modest increase in the protonophore resistance of growth and ATP synthesis. Growth of the wild type at elevated temperatures, in the absence of fatty acid supplementation, also enhanced its resistance to protonophores. The results support the hypothesis that specific changes in membrane lipid composition underlie the bioenergetic changes associated with protonophore resistance.