Acid Composition Of Membranes Research Articles

Insights into molecular pathways and fatty acid membrane composition during the temperature stress response in the murine C2C12 cell model

Daily and seasonal temperature fluctuations are inevitable due to climate change, which highlights the importance of studying the detrimental effects of temperature fluctuations on the health, productivity, and product quality of farm animals. Muscle membrane composition and the molecular signals are vital for muscle cell differentiation and muscle growth, but their response to temperature stress is not well characterized. Temperature changes can lead to modification of membrane components of the cell, which may affect its surroundings and intracellular signaling pathways. Using C2C12 myoblast cells as a model of skeletal muscle development, this study was designed to investigate the effects of high temperature (39 °C and 41 °C) and low temperature (35 °C) on molecular pathways in the cells as well as the cell membrane fatty acid composition. Our results show that several genes were differentially expressed in C2C12 cells cultured under heat or cold stress, and these genes were enriched important KEGG pathways including PI3K-Akt signaling pathway, lysosome and HIF- signaling pathway, Wnt signaling pathway and AMPK signaling pathway. Our analysis further reveals that several membrane transporters and genes involved in lipid metabolism and fatty acid elongation were also differentially expressed in C2C12 cells cultured under high or low temperature. Additionally, temperature stress shifts the fatty acid composition in the cell membranes, including the proportion of saturated, monounsaturated and polyunsaturated fatty acids. This study revealed an interference between fatty acid composition in the membranes and changing molecular pathways including lipid metabolism and fatty acids elongation mediated under thermal stress. These findings will reinforce a better understanding of the adaptive mechanisms in skeletal muscle under temperature stress.

Fatty acid composition of mitochondrial membranes of pea germs exposed to insufficient watering and treated with organophosphorous plant growth regulator

The influence of insufficient watering and a melamine salt of bis(oxymethyl)-phosphonic acid (melaphen) on fatty acid composition of mitochondrial membrane of pea seedlings has been studied. It is shown that insufficient watering results in a 1.57-fold decrease in the ratio of unsaturated to saturated C18 fatty acids and in a 3.04-fold decrease in the ratio of unsaturated to saturated C20 fatty acids. The modification of fatty acid composition of mitochondrial membranes was associated with the alterations in their functional state: maximal rates of oxidation of NAD-dependent substrates and the rates of electron transport at the end of respiratory chain decreased. A preliminary treatment of the seeds with 3 × 10−9 M melaphen restored the maximal rates of oxidation of NAD-dependent substrates to the control values. We suggest that the alterations of the electron transport rates in respiratory chain in mitochondria are related to the physicochemical state of the membranes of these organelles, as the treatment with melaphen prevented the changes in fatty acid composition of the membranes of seedlings growing under the conditions of insufficient watering.

Common genetic variants of the FADS1 FADS2 gene cluster and their reconstructed haplotypes are associated with the fatty acid composition in phospholipids

Fatty acid composition in membranes plays an important role in cellular processes and has shown to be associated with the aetiology of several complex diseases in humans. We report strong associations between variants in the human delta-5 and delta-6 desaturase genes FADS1 FADS2 and fatty acid composition in serum phospholipids. Eighteen polymorphisms located in this gene cluster were genotyped in 727 adults from Erfurt, a German centre of the European Community Respiratory Health Survey. The cluster is located at chromosome 11q12-11q13.1, a region repeatedly found to be linked with atopy and other complex diseases. Polymorphisms and statistically reconstructed haplotypes of FADS1 and the upstream region of FADS2 showed strongest associations with the level of the direct precursor of inflammatory eicosanoids, the n-6 fatty acid arachidonic acid (C20:4n-6), also strong associations with levels of the n-6 fatty acids C18:2n-6, C18:3n-6, C20:2n-6, C20:3n-6, C22:4n-6 and of the n-3 fatty acids C18:3n-3, C20:5n-3 and C22:5n-3 (P-values < 1.0 x 10(-13)). Carriers of the rare alleles of several SNPs and their respective haplotypes had a lower prevalence of allergic rhinitis and atopic eczema. No association was found for total and specific IgE levels.

Dietary fatty acids modify insulin secretion of rat pancreatic islet cells in vitro.

The type of dietary fat affects the action of insulin by changes induced in the fatty acid composition of cell membranes. Little is known, however, about the effects of dietary fatty acids on insulin secretion or the possible relation between the fatty acid composition of the membrane phospholipids and insulin secretion. We therefore studied the effects of dietary fatty acids on insulin secretion stimulated by glucose, forskolin and arginine, and on the insulin content of isolated pancreatic islets, as well as on the fatty acid composition of muscle phospholipids, which were used as markers of the diet-induced modifications in the cell membranes. Five groups of rats were fed for one month with diets varying only in their fat composition: olive oil, sunflower oil, soybean oil, fish oil and palmitic acid (16:0) + soybean oil (SAT). The SAT group had higher insulin secretion, independently of the secretagogue used. No significant differences were found in insulin content between the groups. The dietary fatty acids modified the fatty acid composition of the muscle phospholipids, both in endogenously synthesized fatty acids and in those which were unable to be synthesized by the organism. No statistically significant relation was found between insulin secretion and the content of certain fatty acids in the muscle phospholipids.

Fatty acid composition of membranes in psychiatric patients

Fatty acid composition of membranes in psychiatric patients

INCREASED CONCENTRATION OF ARACHIDONIC ACID IN ERYTHROCYTE MEMBRANES IN CHRONICALLY LEAD-EXPOSED MEN

Animals intoxicated by lead present alterations in the fatty acid composition of red blood cells (RBC). Since this altered fatty acid com position of membranes may be a general reflection of lead toxicosis, we have examined 12 clinically healthy leadexposed male subjects for fatty acid composition of RBC membranes along with blood lead, serum calcium, and serum iron concentrations. Twelve unexposed age-matched male subjects were used as controls. Significantly increased levels of arachidonic acid (AA) were found as compared to matching healthy controls in the RBC of the leadexposed subjects. The increase of AA correlated in a dose-dependent manner with elevation in lead, and with serum iron, while a negative correlation was found between AA and serum calcium. The known ability of lead to substitute for calcium, which is essential in activating phospholipase A2 for AA release from membrane phospholipids, may be the main reason for increased AA in RBC membranes.

Maturation of bacteriophage 9NA DNA is influenced by the fatty acid composition of the host cell membrane

The fatty acid composition of the membrane of the conditional auxotroph fabB2 can be altered by allowing the cells to grow at non-permissive temperature (37°C) in the presence of a cis-unsaturated fatty acid. The phage 9NA, a virulent phage of Salmonella typhimurium, can not multiply in fabB2. Synthesis and maturation of the phage DNA are differentially affected by variation in the fatty acid composition of the cell membrane. The replicating DNA associates with the membrane complex, the site of DNA synthesis. The association is comparatively weak in oleic, claidic, palmitoleic, palmitelaidic and linolelaidic acid enriched cells. When the cells are grown in the presence of palmitoleic acid, a large pool of concatemeric phage DNA accumulates in the cytoplasm within 10 min of infection. The conversion of concatemeric DNA to monomeric one i.e., mature phage length DNA, is inhibited in such cells. The presence of concatemeric DNA can be visualized by electron microscope. Such a situation is not observed when the cells are grown in media supplemented with other types of unsaturated fatty acids. The mechanism by which the host cell membrane lipid controls phage development is yet to be worked out.

Red blood cells and platelet membrane fatty acids in non-dialyzed and dialyzed uremies

Three groups of patients with chronic renal failure (CRF), 16 non-dialyzed, 16 undergoing haemodialysis (HD), 16 undergoing continuous ambulatory peritoneal dialysis (CAPD), and 48 controls were examined. We analyzed the fatty acid composition in membranes from erythrocytes and platelets and the platelet malondialdehyde (MDA) production as an index of thromboxane metabolism. Marked differences in erythrocytes fatty acid composition were observed between patients with CRF and controls and, particularly, among the three groups of patients with CRF. Patients on CAPD were characterized by an increase in oleic acid, while haemodialyzed had a marked increase in arachidonic acid. Platelet fatty acid composition showed similar differences, suggesting a ‘systemic’ membrane abnormality. Platelet MDA was increased in haemodialyzed and positively correlated with the platelet arachidonate content.

Dietary fat alters the fatty acid composition of lymphocyte membranes and the rate at which suppressor capacity is lost.

SJL/J mice were fed from conception two nutritionally adequate semi-purified diets that differed only in polyunsaturated to saturated fatty acid content. The effect of diet fat on the fatty acid composition of membranes from spleen and thymus cells was determined. Diet fat was found to significantly alter the fatty acid composition of lymphocyte membrane phosphatidylcholine and phosphatidylethanolamine. Diet also altered the degree of resistance against tolerance-induction.

Fatty acid composition of membranes of L-forms ofStreptococcus faecalis andProteus mirabilis cultured at different osmolalities

The fatty acid composition of membranes of L-forms ofStreptococcus faecalis andProteus mirabilis cultured at different osmolalities and in different osmotic stabilizers was examined.S. faecalis L-forms cultured with sucrose in the medium showed a decrease in the unsaturated fatty acid C18∶1 and an increase in the C18 fatty acid and C19 cyclopropane fatty acid. Fatty acid composition ofS. faecalis L-forms cultured in medium containing 1.8% NaCl was similar to the fatty acid composition of L-forms cultured in brain-heart infusion broth (BHI) without osmotic stabilizer and was between the composition of fatty acids of L-forms in BHI with sucrose and that in BHI without 0.5 M sucrose. InProteus mirabilis L-forms, there were differences between L-forms cultured with and without sucrose, but these differences were not comparable to the changes observed inS. faecalis L-forms.P. mirabilis L-forms cultured with and without NaCl in the medium had similar fatty acid compositions.

Temperature dependence of membrane-bound enzymes of the energy metabolism in Rhodospirillum rubrum and Rhodopseudomonas sphaeroides

Rhodospirillum rubrum grown either chemotrophically or phototrophically at 14°C and 30°C, was employed to study the effect of temperature on fatty acid composition as well as on several membrane bound functions involved in energy metabolism. Upon growth at both temperatures the fatty acid composition of membranes showed differences, which could be attributed to an incomplete formation of photosynthetically active membranes rather than specifically to the growth temperature. Activities of NADH dependent respiration and light induced proton extrusion by cells did not show discontinuities in Arrhenius plots down to temperatures of 15°C and 5°C, respectively. In contrast, coupling factor Mg2+- and Ca2+-ATPase as well as succinate cytochrome c oxidoreductase showed significant breaks at 20°C and 18°C, respectively. Similarly, in Rhodopseudomonas sphaeroides. NADH dependent respiration and light induced proton extrusion by cells was continuous over the entire range of temperatures applied. ATPase as well as succinate cytochrome c oxidoreductase, on the other hand, featured discontinuities in Arrhenius plots at 20°C and 19°C. The implication of the data on growth rates and membrane structure are discussed.

Fatty Acid-requiring Mutant of Bacillus subtilis Defective in Branched Chain α-Keto Acid Dehydrogenase

A new mutant of Bacillus subtilis is described lacking the activity of branched chain α-keto acid dehydrogenase. The mutant requires short branched chain fatty acids biosynthetically related to leucine, isoleucine, and valine for growth. Long branched chain fatty acids derived from these short molecules can also serve as growth factors. One type of branched chain fatty acid, however, is sufficient to support growth of the mutant at 37°, although wild type cells of B. subtilis normally contain three different pairs of long branched chain fatty acids. Therefore, this mutant allows extensive alterations of the fatty acid composition in membranes of B. subtilis. Straight chain fatty acids do not support growth. Out of a series of tested analogues, 2-methylvalerate, 2-ethyl butyrate, and trimethylacetate were found to be active in vivo as primer molecules of branched chain fatty acid biosynthesis. The chain-lengthened products derived from these primer substrates were characterized by mass spectrometry.

Fatty acids of RBC ghosts, liver mitochondria and microsomes of cold-acclimated hamsters.

SummaryWhen hamsters were exposed to cold, the relative percentage of various fatty acids in mitochondrial and microsomal membranes of liver cells changed. In mitochondria, the percentage of oleic acid increases, and in microsomes the percentages of oleic increased and palmitic acid decreased. These findings are in contrast to results of earlier studies on whole livers, which showed that under similar conditions, the percentage of stearic acid decreases. There were no changes in fatty acid percentage composition in RBC ghost cells after 5-9 weeks of exposure. These studies also indicate that there were striking differences in the fatty acid composition of membranes of various organelles in the cell.