Unsaturated Fatty Acid Composition Research Articles

Diet fat influences liver plasma-membrane lipid composition and glucagon-stimulated adenylate cyclase activity.

Rats were fed diets that differed in fatty acid composition or in the proportion of energy derived from fat to determine if alteration of dietary fat intake influences the structural lipid composition of liver plasma membrane and the expression of an associated hormone-receptor-mediated function. Weanling rats were fed 9% (w/w) or 20% (w/w) low-erucic acid rape-seed oil or 9% (w/w) soya-bean oil for 24 days. Plasma membranes were isolated and the effect of diet fat on the fatty acid composition of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol and sphingomyelin was determined. Diet fat significantly altered total saturated and (omega-9) and (omega-6)-unsaturated fatty acid composition in addition to the (omega-6)- to (omega-3)-unsaturated fatty acid ratio in these polar lipids. Feeding the high-fat diet increased the (omega-6)- to (omega-3)-unsaturated fatty acid ratio and the (omega-9)-unsaturated fatty acid content in all lipids except sphingomyelin. Assay of glucagon-stimulated adenylate cyclase activity at both high and low glucagon concentrations indicated that high-fat intake also decreased cyclic AMP formation. In a second experiment the fat intake was held constant (40% of energy) and oleic acid was substituted for linoleic acid by blending high- and low-linoleic acid-type safflower oils. This experiment established that a dose-response relationship exists between dietary intake of fatty acid and the fatty acid composition of plasma-membrane phospholipids. Specific diet-induced transitions in membrane phospholipid fatty acid composition were paralleled by changes in glucagon-stimulated adenylate cyclase activity. This study suggests that transitions in dietary fat intake can alter a hormone-receptor-mediated enzyme function in vivo by changing the surrounding lipid environment.

Toxicity of activated oxygen: Lack of dependence on membrane unsaturated fatty acid composition

Membrane unsaturated fatty acid oxidation has been suggested as a mechanism of toxicity for a variety of activated oxygen species. We have tested this hypothesis by manipulating the fatty acid composition of an Escherichia coli mutant that is unable to synthesize unsaturated fatty acids. To provide a wide range of susceptibility to membrane oxidation we have replaced the naturally occurring monoenoic acyl chains with cyclopropanes to greatly reduce the unsaturation level and with linoleate to increase the membrane unsaturation. These cultures were treated with ozone, hydrogen peroxide, singlet oxygen and paraquat. In no case was there substantial protection from toxicity afforded by cyclopropanes nor was there enhancement of toxicity to cells with the polyunsaturated membranes. We suggest, therefore, that oxidation of membrane unsaturated fatty acids is not an essential component of the toxicity to E. coli of active oxygen species.

Progress in the Selection for Altered Fatty Acid Composition in Soybeans1

Progress in the selection for altered unsaturated fatty acid composition in soybeans [Glycine max (L.) Merr.] was evaluated. N78‐2245, an experimental line developed through recurrent selection methodology contained 51% oleic acid (18:1), 31.9% linoleic acid (18:2), and 4.2% linolenic acid (18:3). In comparison ‘Dare,’ a representative cultivar, contained 21.4% 18:1, 55.6% 18:2, and 8.9% 18:3. This investigation has demonstrated that both soybean fatty acid composition and glycerolipid fatty acid composition were influenced by genetic manipulation.

Correlation of hyperthermic sensitivity and membrane microviscosity in E. coli K1060.

We have demonstrated a positive correlation between membrane microviscosity and the temperature required to kill E. coli. Batches of cells with differing unsaturated fatty acid (u.f.a.) compositions were prepared from the u.f.a.-requiring E. coli K12 mutant K1060. The membrane microviscosity of these cells is estimated from the extent of fluorescence polarization of the probe molecule 1,6-diphenyl-1,3-5,-hexatriene dissolved in the membrane. For the same growth temperature, cells grown in oleic acid (18:1) have a greater microviscosity and u.f.a. content than linolenic acid (18:3) grown cells. the rate of decrease in microviscosity with increasing temperature is correlated with the amount of u.f.a. present in the membrane. From survival curves determined at several hyperthermic exposures, one can interpolate the hyperthermic temperature required to kill 90 per cent of the cells in three hours. These equivalent kill temperatures are directly related to the cell microviscosity. These data support the hypothesis that cell membrane microviscosity plays a critical role in hyperthermic killing.

Studies of the fatty acid composition and membrane microviscosity in Salmonella typhimurium TA98

When the mutagen tester bacterial strain Salmonella typhimurium TA 98 was grown at different temperatures, we found that the unsaturated fatty acid composition increased at the lower growth temperatures. Membrane microviscosity, as assessed with spin-probe fatty acids using electron spin resonance, decreased as the unsaturated fatty acid content increased. These findings are of importance in understanding our recent observation that the mutagenic response of these bacteria was increased when they were grown at 27°C vs. 37°C, and indicate that membrane properties may play an important role in the sequence of events leading to mutagenesis.

Dietary Alteration of Palatability and Fatty Acids in Meat from Light and Heavy Weight Ram Lambs

Forty-four wholesale ribs from ram lambs fed one of five corn:roughage diets and slaughtered at 41 or 68 kg live weight were evaluated for differences in fatty acid composition and palatability. Total unsaturated fatty acids in subcutaneous fat were higher for lambs on diets that contained 72.57 or 79.50% corn than on diets that contained 0, 36.29 or 37.88% corn. Total polyunsaturated fatty acids followed the same trends; higher amounts were present in diets that were high in corn. Differences (P<.05) in flavor scores of ram lamb meat by diet were not related to changes in unsaturated fatty acid composition. In addition, the effect of diet on aroma, juiciness, tenderness and Warner-Bratzler shear values was not significant. Total unsaturated fatty acids were higher in fat from 68-kg lambs than from 41-kg lambs, but total polyunsaturated fatty acids decreased as weight increased. Panel scores for flavor were less desirable in rib roasts from older 68-kg rams than from younger 41-kg ram lambs, but panel scores for aroma of heated fat, juiciness and tenderness were not related (P<.05) to weight. Warner-Bratzler shear values were lower for meat from the 68-kg ram lambs than for meat from the 41-kg ram lambs. The data demonstrate that diet can influence fatty acid composition in ram lambs and that diet should be an important consideration in production of ram lambs for meat. However, the influence of diet and fatty acid composition on flavor and aroma of meat from ram lambs needs further study.

Relationship between Chloroplast Membrane Fatty Acid Composition and Photosynthetic Response to a Chilling Temperature in Four Alfalfa Cultivars

The photosynthetic responses of four alfalfa (Medicago sativa L.) cultivars to 10 and 22 C air temperatures were examined and the relationship between the photosynthetic response at 10 C and the fatty acid composition of the chloroplast membranes was determined. Chilling-resistant cultivars exhibited moderate reductions in photosynthesis at 10 C, compared to 22 C, and contained a significantly greater percentage of polyunsaturated fatty acids in the chloroplast membrane and a greater double bond index than the chilling-sensitive cultivars. The chilling-sensitive cultivars exhibited severe reductions in photosynthesis at 10 C, compared to 22 C. The reduction in photosynthesis at 10 C is shown to be negatively correlated (r = -0.94) with the double bond index of the chloroplast membranes of the cultivars observed.The results support the hypothesis that reduced photosynthesis due to chilling temperatures is influenced by the unsaturated fatty acid composition of the chloroplast membrane which affect temperature-induced phase changes in chloroplast membrane lipids.

The effects of temperature and growth rate on the proportion of unsaturated fatty acids in bacterial lipids.

The effects of temperature and growth rate on the fatty acid composition of the extractable lipids of four mesophilic and three psychotrophic bacteria were examined. Two of the mesophiles (Escherichia coli and Pseudomonas aeruginosa) increased the proportion of unsaturated fatty acids in their lipids with decreasing temperature over their whole growth temperature range. The other mesophiles (Enterobacter aerogenes and Lactobacillus casei) increased the proportion of unsaturated fatty acids with decreasing temperature only over the lower half of their growth temperature ranges. The psychrotrophs Pseudomonas fluorescens and Enterobacter sp. had a constant proportion of unsaturated acids over the lower half of their growth temperature range, while the psychotrophic Lactobacillus sp. showed no consistent change in its unsaturated fatty acid composition with temperature. All species showed some variation of unsaturated fatty acid composition with growth rate at the highest and lowest growth temperatures, although such variations were small in some species (Ent. aerogenes and Lactobacillus sp.).

Vasodilatory action of arachidonic acid in humans following indomethacin treatment

1.1. The quantitative and qualitative compositions of higher unsaturated fatty acids of 51 species of marine invertebrates, collected in Peter the Great Bay, Japan Sea, have been determined.2.2. Eicosapentaenoic acid, C20:5, was shown to be characteristic of most species of invertebrates.3.3. The analysis of a number of invertebrates from Japan Sea showed the echinoderms to be the most rich both in the quality and quantity of polyunsaturated fatty acids.

Fatty acid composition changes in mitochondrial membranes induced by dietary long chain fatty acids

The cardiopathogenic effects of dietary rapeseed oil have been reviewed [ 11. Fatty infiltration of rat cardiac muscle observed after short periods of high erucic acid rapeseed oil feeding [2,3] may be related to a decreased efficiency of mitochondrial ATP synthesis [4-61. Similar feeding experiments have shown the preferential incorporation of erucic acid into mitochondrial cardiolipin [7], an integral component of cytochrome oxidase [8]. Therefore it is of interest to investigate whether a transition in mitochondrial membrane ,fatty acid composition corresponding to changes in mitochondrial function [6] can be related to rapeseed oil containing diets. Study of the relationship of essential fatty acids to structural and functional properties of biological membranes has been made [9161 but specific roles in mitochondrial membrane functions are not clear. However, it is known that: changes in unsaturated fatty acid composition of essential fatty acid depleted mitochondria significantly influence oscillation period and freedom of spin label motion, properties dependant upon large domains of the mitochondrial membrane [ 151, specific phospholipids are required for catalytic activity of mitochondrial enzymes [ 17191 and in addition, peroxidation of fatty acyl moieties has been correlated with the loss of metabolic function [ 16,201. In the present work changes in the fatty acid composition of cytochrome containing membrane fractions were correlated to diet. Increases in n-9

Effect of essential fatty acid deficiency on activity of liver plasma membrane enzymes in the rat

Liver plasma membranes (LPM) were isolated from rats fed an essential fatty acid-supplemented diet (+EFA) or from rats fed an essential fatty acid-deficient diet (-EFA). The proportions of linoleate and arachidonate in membrane total fatty acids in the -EFA preparations were one-half or less than the values for the +EFA preparations. Basal, F-, or glucagon-stimulated adenylate cyclase activities were significantly lower in EFA-deficient livers than in nondeficient ones. Addition of GTP significantly enhanced glucagon-stimulated adrenylate cyclase in both groups, but extent of stimulation above basal was greater in EFA-deficient livers. Portal vein injection of glucagon in vivo resulted in significantly higher cAMP formation in +EFA livers than in -EFA livers. When glucagon was used in vitro at 1-1,000 nM, stimulation of adenylate cyclase remained lower in EFA-deficient membranes, but extent of stimulation above basal activity was larger in -EFA membranes than in +EFA. Total Na+, K+ (Mg2+)-ATPase from EFA-depleted LPM exhibited significantly higher values of apparent Km and Vmax-5'-Nucleotidase activity, in contrast, was considerably decreased in EFA-deficient rats. These findings show that, in animals, changes in unsaturated fatty acid composition can affect the properties of membrane-bound enzymes. These alterations could be due to changes in membrane physical properties and/or prostaglandin formation.

Studies to determine the role rates of chain elongation and desaturation play in regulating the unsaturated fatty acid composition of rat liver lipids

Rat liver microsomes were used to measure the rates of chain elongation and desaturation of acids in the linoleate, oleate and palmitoleate biosynthetic pathways. These studies were designed to determine whether there is a relationship between rates of conversion and the types of unsaturated fatty acids found in rat liver lipids. In some cases rates of conversion correlate well with the types of unsaturated fatty acid found in rat liver lipids. In other cases, rates of conversion must be correlated with other controls such as competitive interactions, retroconversion, and specificities for incorporating given acids into lipids in order to explain the unsaturated fatty acid composition of rat liver lipids. The roles and interrelationships of these various metabolic processes are discussed relative to the control of polyunsaturated fatty acid biosynthesis.

Biogenesis of mitochondria: The effects of altered steady-state membrane lipid composition on mitochondrial-energy metabolism in Saccharomyces cerevisiae

A chemostat culture technique has been developed for the growth of an unsaturated fatty acid auxotroph of Saccharomyces cerevisiae. Any chosen steady-state cellular unsaturated fatty acid level between 75 and 15% of the total fatty acids could be established and maintained. In all cultures the steady-state glucose concentrations were maintained at levels below that which induces catabolite repression. The efficiency of oxidative phosphorylation as determined from the molar growth yield decreased as the cellular unsaturated fatty acid composition was lowered. The number of moles of ATP produced by oxidative phosphorylation per mole of glucose utilized was 7.2, 4.8, 0.7, and 0.4 for cells in which 75, 50, 44, and 34%, respectively, of the total fatty acids were unsaturated. The lesion in oxidative phosphorylation was a direct result of lowering the membrane unsaturated fatty acid composition as the respiratory activities and cytochrome content of cells and mitochondria were unaffected by a decrease in the cellular unsaturated fatty acid level from the wild-type value of about 75% down to about 34%. In cells which contained lipids with 22–28% unsaturated fatty acids, cyanide-sensitive respiration was absent, and the levels of all mitochondrial cytochromes were less than 10% of normal. The reduction in the levels of cytochromes aa 3 and b appeared to be a consequence of a loss of mitochondrial protein synthetic activity in such cells. The level of cytochrome c was also greatly decreased, indicating that the cellular unsaturated fatty acid composition was affecting either the synthesis in the cytoplasm of mitochondrial proteins or the assembly of these proteins in the mitochondria.

Alteration of fatty acid composition of LM cells by lipid supplementation and temperature.

Alteration of the fatty acid composition of monolayer cultures of LM cells grown in chemically defined medium was achieved by supplementation with fatty acids complexed to bovine serum albumin. Phospholipids containing up to 40% linoleate were found in cells grown in medium containing 20 mu g of linoleate/ml. Incorporation of linoleate into phospholipids reached a plateau after 12-24 hr, and cells remained viable for at least 3-4 days. Although linoleic, linolenic, and arachidonic acids were incorporated into LM cells equally well, only the latter was elongated by these cells under these experimental conditions. Nonadecanoic acid was incorporated to a lesser extent than the polyunsaturated fatty acids. Phosphatidylcholine and phosphatidylethanolamine of LM cells had different fatty acid compositions; phosphatidylethanolamine contained more longer chain and unsaturated fatty acids. Cells were also grown in the absence of choline and presence of choline analogs such as N,N-dimethylethanolamine, N-methylethanolamine, 3-amino-1-propanol, and 1-2-amino-1-butanol. The analog phospholipids in these cells had fatty acid compositions which were intermediate between those of phosphatidylethanolamine and phosphatidylcholine of control cells grown in the presence of choline. Linoleate was found in both phosphatidylcholine and phosphatidylethanolamine of cells supplemented with linoleate. The sphingolipid fraction of these cells, however, did not contain significant amounts of linoleate. When linoleate was present in the phospholipids, compensatory decreases in the oleate and palmitoleate content of phospholipids were observed. Lowering of the growth temperature to 28 degrees produced an increase in unsaturate fatty acid content of the phospholipids. When linoleate was supplied to cells grown at 28 degrees, there was no further increase in the unsaturated fatty acid composition of the phospholipids. Using both fatty acid supplementation and lowered growth temperature, LM cell membranes can be produced which have phospholipids with vastly different fatty acid compositions.

Oscillatory states of mitochondria: Influence of unsaturated fatty acid composition

Experiments were done to test whether maintenance of more rapid mitochondrial volume oscillations in rats supplemented with essential fatty acids (EFA) was related to overall unsaturation of fatty acids in mitochondrial lipids or to the presence of specific essential fatty acids. Liver mitochondria from EFA-deficient rats showed a decrease in frequency of oscillations of ion transport in comparison with nondeficient rats receiving corn oil as a source of linoleic acid. Supplementation of EFA-deficient rats with methyl linoleate (18:2ω6), methyl linolenate (18:3ω3) or methyl arachidonate (20:4ω6) made the oscillation frequency very similar to that of mitochondria from nondeficient rats. Supplementation with methyl docosahexaenoate (22:6ω3) had no effect, despite the high degree of mitochondrial fatty acid unsaturation produced by feeding this fatty acid. The ineffectiveness of 22:6ω3 is evidence that increased unsaturation is not the main factor in the maintenance of the oscillation frequency in rat liver mitochondria. The effectiveness of the other methyl ester supplements is evidence for a specific need for 20:4ω6 or 20:5ω3 either for mitochondrial function or for prostaglandin formation.

Unsaturated fatty acid composition of wild type and respiratory deficient yeasts after aerobic and anaerobic growth.

An analysis is given of the fatty acid composition of 18 yeast species, predominantly of the genus Saccharomyces; respiratory deficient mutant strains are included. The results are discussed from chemotaxonomical and physiological viewpoints, with special attention to unsaturated fatty acids and their relation to the petite mutation.

The fatty acid and phospholipid composition of longissimus dorsi muscle from Pietrain and Large White pigs.

AbstractAn examination was made of the fatty acid and phospholipid composition of longissimus dorsi muscle from Pietrain and Large White pigs. The neutral lipid fraction from Pietrain muscle had a more unsaturated fatty acid composition possibly because of a reduced rate of intramuscular fat deposition in these pigs. The phospholipid content of muscle and muscle sarcoplasmic reticulum was similar in both breeds. The fatty acid composition of phospholipid and the concentrations of individual phospholipids were also similar.Differences in the lipid composition of muscle between the breeds appear to reflect a reduced capacity for carcass fat deposition in Pietrains rather than the propensity of pigs of this breed to produce muscle which is pale, soft and exudative (p.s.e.).

Relation of unsaturated fatty acid composition of rat liver mitochondria to oscillation period, spin label motion, permeability and oxidative phosphorylation

An investigation was made of the influence of mitochondrial unsaturated fatty acid composition on the following mitochondrial parameters: oscillation period, spin label motion (ESR), permeability, and oxidative phosphorylation. Liver mitochondria from rats fed diets deficient in or supplemented with essential fatty acids showed approximately the same total number of unsaturated fatty acids but changed unsaturation levels. Electron microscopy showed that the morphology of the inner membrane compartment was unchanged. Two differences were correlated with unsaturated fatty acid composition: (1) a slower frequency (or time period) of the oscillatory state of energy-dependent ion transport and (2) a reduction in the motional freedom of each of three spin labels (12NS, 5N10 and 7N14). The increase in oscillation period could arise from a number of rate-limiting processes, including permeability of mitochondria to various anions, cations, and substrate metabolites. However, when the permeability of mitochondria to such substances was tested, no changes were observed in passive or active uptake of these substances or in the efficiency of oxidative phosphorylation under steady-state conditions. Thus, the two parameters, oscillation period and freedom of spin label motion, which are dependent upon large domains of the mitochondrial membranes, are significantly influenced by the change in unsaturated fatty acid composition in essential fatty acid-depleted mitochondria, even though processes such as permeability of ionic materials and oxidative phosphorylation were not measurably affected by these changes in unsaturated fatty acid composition.

Short-term exposure to nitrogen dioxide. Effects on pulmonary ultrastructure, compliance, and the surfactant system

A group of 13 beagles were artificially ventilated with air containing from 0 to 16 ppM NO/sub 2/ for one hr. Levels sbove 7 ppM were associated with acute edema, higher wet weight/dry weight lung ratios, abnormal lung function, and decrease in cardiac output and stroke volume. Where edema was present, regardless of NO/sub 2/ level, there was less surface tension, although surfactant itself was not destroyed. Also lower phospholipid content (36% as opposed to 52% in normal dog), lower lecithin (chief phospholipid surfactant) and abnormal increase in unsaturated lecithin fatty acid composition were noted. Some cell membrane damage was found in 5 animals exposed to 3 to 12 ppM NO/sub 2/ but other parameters were generally normal. Damage, as evidenced by swelling of cells and mitochondria and loss of pinocytotic vesicles, was scattered at 3 ppM but increased with higher exposures. Debris was found in alveolar spaces. Acute effects were apparently not proportional to NO/sub 2/ level, but membrane damage occurred at lowest concentration (3 ppM). Five ppM for 1 hr was the apparent threshold for serious effects. Impairment of surfactant was possibly due to: binding of active phospholipid sites, alteration of phospholipid sturcture, or dilution by non-active lipidsmore » (e.g., cholesterol) from damaged tissue and plasma.« less

Platelet lipids. V. Saturated and unsaturated fatty acid composition of phospholipids from rabbit platelets incubated with different media.

Abstract Both individual and combined incorporation ratios of labelled linoleic and palmitic acids, into single phospholipid fractions of isolated rabbit platelets were analyzed. When both fatty acids were present in the incubation medium, lecithin and phosphatidylinositol incorporated more palmitic than linoleic acid and the ratio increased with time. In contrast, sphingomyelin and phosphatidylethanolamine showed the opposite behaviour. With phosphatidylserine incorporation of linoleic acid predominated during the first 30 min but by 60 min palmitic acid predominated by a ratio of 2:1. Comparison of this data with that obtained from single fatty acid incubations suggests that specific and competitive incorporation occurs in phospholipids depending upon the incubation media. Lecithin for instance incubated with a single fatty acid incorporates more linoleic than palmitic acid, while dual incubation results in more palmitic acid incorporation. Structural platelet lipid modification dependent on fatty acid composition of the incubation medium is discussed.