Degree Of Fatty Acid Unsaturation Research Articles

Structural stabilization of lipids and the visual pigment rhodopsin in the photoreceptor membrane by vitamin E

Interaction of alpha-tocopherol with free fatty acids in bovine retinal photoreceptor membranes was studied using ESR spin-probe technique and measurements of rhodopsin thermal denaturation rates. Exogenous alpha-tocopherol incorporated into photoreceptor membranes prevented thermal destabilization of rhodopsin caused by free fatty acids. The efficiency of the stabilizing action of alpha-tocopherol directly depended both on the chain length and the degree of fatty acid unsaturation.

Temperature-dependent changes in phospholipid and fatty acid composition and membrane lipid fluidity of Yersinia enterocolitica

Temperature‐dependent compositional changes of phospholipids and their fatty acids were analysed in Yersinia enterocolitica grown at 5°, 25° and 37°C. The relative amounts of the four phospholipids, phosphatidylethanolamine (75–78%), phosphatidylglycerol (10–11%), cardiolipin (<7%) and lysophosphatidylethanolamine (<5%), were essentially the same at all growth temperatures. The degree of fatty acid unsaturation of the four phospholipids increased with decrease in growth temperature, mainly due to an increase of C16:1 and C18:1 and a corresponding decrease of C16;0, C18:0 and cyclo C17:0. An electron spin resonance spectroscopic study of the membrane lipids showed that membrane lipid fluidity was enhanced by decreasing the growth temperatures. The changes in fatty acid composition of phospholipids in response to varied temperatures were consistent with the temperature‐dependent changes in the membrane lipid fluidity of Y. enterocolitica, and were similar to those reported for other bacteria.

The Role of Lipids in the Interaction of Acholeplasma laidlawii Cells with Lymphocytes

The role of A. laidlawii membrane lipids in the organism's interaction with mouse spleen lymphocytes is analyzed. A. laidlawii cells were grown in a lipid-poor medium with unsaturated fatty acids that allowed cells with different degrees of membrane lipid microviscosity to be obtained. The intensity of the binding of A. laidlawii cells and derived liposomes with lymphocytes depended directly on the degree of fatty acid unsaturation. Cholesterol incorporation into the A. laidlawii membrane reduced the fluidity of the lipid bilayer and decrease the binding activity. The intensity of cholesterol transfer from lymphocytes to A. laidlawii also depended on the degree of fatty acid unsaturation in A. laidlawii cells. Cells enriched with cholesterol took up considerably less of this sterol from lymphocytes. The loss of cholesterol as well as the enrichment of lymphocytes by A. laidlawii membrane fatty acids resulted in a decrease in the microviscosity of lymphocyte membrane lipids. It was concluded that the ability of A. laidlawii cells or derived liposomes to stimulate the transport of carbohydrates into lymphocytes depended on the degree of unsaturation of fatty acid incorporated into A. laidlawii. Cholesterol also decreased the stimulatory effect, probably by lowering carbohydrate carrier mobility.

キュウリ品種とクロダネカボチャの根のりん脂質含有率とその脂肪酸組成に及ぼす根温の影響

The effect of root temperature on phospholipid concentration and its fatty acid composition in the roots was studied with cucumber (Cucumis sativus L., cvs. Kurume-ochiai H and Suyo) and figleaf gourd (Cucurbita ficifolia Bouché) which have contrasting tolerance to low root temperature.Phospholipid concentration in roots increased at 14°C and more so at 12°C in figleaf gourd, which is highly tolerant of low root temperature compared to cucumber. In both cultivars of cucumber, however, the concentration increased only at 12°C. The increase in phospholipid concentration in figleaf gourd roots was assumed to be due to the net increase of phospholipid synthesis within roots, but that in cucumber roots seemed to be a result of root growth inhibition. Composition of phospholipids was relatively unaffected by root temperature in all crops; phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were the main phospholipid species in the roots of all three crops.The degree of fatty acid unsaturation of total phospholipids increased steadily in figleaf gourd as the root temperature was lowered from 25 to 12°C. By contrast, in‘Suyo’, which is the most intolerant of low root temperature among the three crops used, degree of fatty acid unsaturation was highest at 17°C and tended to decrease toward the lowest root temperature. In‘Kurume-ochiai H’it was almost unaffected by root temperature. With reduction in root temperature, fatty acid unsaturation of PE increased with little changes in that of PC in figleaf gourd. Conversely, in both cultivars of cucumber fatty acid unsaturation of PE varied little, and instead, that of PC decreased at 12°C, more greatly in‘Suyo’.From these results it is suggested that the response of roots to low root temperature in phospholipid synthesis and its fatty acid unsaturation is related to different tolerance of these crops to low root temperature.

Membrane alterations in cancer cells: the role of oxy radicals.

Membranes isolated from tumor cells present profound alterations in their composition, structural organization, and functional properties. In this study we have reported some of these alterations in microsomal and plasma membranes of hepatomas with different growth rate and degree of differentiation. The chemical parameters studied were the phospholipid-to-protein, the cholesterol-to-protein, and the cholesterol-to-phospholipid ratios and the fatty acid composition of the phospholipids. The physical parameters were the molecular order (static) and the fluidity (dynamic), determined, respectively, as the order parameter [P2] and the correlation time tau R of the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH). The functional property investigated was the ability of the membranes to undergo superoxide-induced lipid peroxidation, determined as byproduct (malondialdehyde and lipid hydroperoxides) formation and as changes in the fatty acid acyl residues. Changes in the physical state of the membrane, induced by oxy radicals, were also monitored during lipid peroxidation. A study of the antioxidant activity of the tumor cell, in terms of oxy radical enzymatic defenses (superoxide dismutase, glutathione peroxidase and catalase) was also performed. The main results obtained are the following: hepatoma membranes possess a lower phospholipid content and a lower degree of fatty acid unsaturation; on the other hand, the cholesterol-to-phospholipid ratio is increased; the physical state appears characterized by an increased rigidity (increased molecular order of the lipids and decreased fluidity); the membrane peroxidizability is markedly depressed and its order parameter, in contrast to liver membranes, does not increase with exposure to the action of O2- radicals; and the oxy radical enzymatic defense mechanisms are decreased. All these alterations increase with increasing growth rate and dedifferentiation of the tumor. Considering all of the data, we are inclined to think that tumor membranes are altered structurally and functionally in part as the result of an oxy radical-induced damage that takes place in vivo under conditions of increased oxygen toxicity.

The fatty acid composition and its alterations due to different incubation temperature in the lipids of aggressive and non‐aggressive strains of Ceratocystis ulmi

AbstractLipids and their fatty acids from the mycelia of aggressive and non‐aggressive strains of Ceratocystis ulmi were examined at different incubation temperature. The quantity and degree of fatty acid unsaturation were correlated with the pathogenicity of the fungus.

Phospholipid surface bilayers at the air-water interface. III. Relation between surface bilayer formation and lipid bilayer assembly in cell membranes

Lipid bilayer assembly in cell membranes has been simulated with total lipid extracts from human red blood cells and from mesophilic and thermophilic bacteria grown at several temperatures. Aqueous dispersions of these natural lipid mixtures form surface bilayers, a single bimolecular lipid state, but only at the growth temperature of the source organism. Thus, a single isolated bilayer state forms spontaneously in vitro from lipids that are available in vivo at the growth temperature of the cell. Surface bilayers form at a specific temperature that is a function of hydrocarbon chain length and degree of fatty acid unsaturation of the phospholipids; this property is proposed as an essential element in the control of membrane lipid composition.

Densitometric quantification of individual phospholipids : Improvement and evaluation of a method using molybdenum blue reagent for detection

A densitometric method for simultaneous quantification of individual phospholipids based on visualization with molybdenum blue reagent is presented. Previously reported problems concerning colour instability have been solved. The method is specific for phosphorus-containing compounds and independent of the degree of fatty acid unsaturation. The molar absorptivities of most analysed phospholipids do not differ more than 10% from that for phosphatidylcholine from egg yolk. For cases of greater deviation (sphingomyelin, lysophosphatidylcholine and phosphatidylserine), analysis is accomplished by use of appropriate standard mixtures. The between-series coefficient of variation is ca. 9%. The method is compared to a preparative thin-layer chormatographic assay and another commonly used densitometric method.

The direct effect of 1,25-dihydroxycholecalciferol on membrane phospholipid composition and phosphate transport.

Current evidence suggests that the mechanism of action of several hormones may be mediated through alterations in membrane lipid composition1–4. Both the content and the degree of fatty acid unsaturation of phosphatidylcholine (PC) in renal proximal tubular and duodenal brush border membranes is increased after 1,25-dihydroxycholecalciferol (1,25(OH)2D3) administration to animals5,6. In both the intestine5’7 and the kidney8 indirect evidence suggests that these lipid changes may be important in stimulating calcium and phosphate transport. In recent studies performed in this laboratory fluorescent phospholipid derivatives have been used to demonstrate that 1,25(OH)2D3 rapidly and directly stimulates the transfer of PC from liposomes to renal brush border membrane vesicles (BBMV)9. The following studies were performed to investigate the effects of 1,25(OH)2D3 induced membrane phospholipid alterations on phosphate transport.KeywordsBrush Border MembranePhosphate TransportPhosphate UptakeBrush Border Membrane VesicleRenal Brush Border MembraneThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Lipid and fatty acid seasonal distribution among tissues of Myriophyllum quitense H.B.K.

Lipid compositions and their constituent fatty acids were determined in submerged and aerial leaves, stems, roots, flowers and fruits of Myriophyllum quitense (M. elatinoides Gaudich.) Mono- and digalactosyldiglycerides represented almost half of the total lipids in submerged leaves, while triacylglycerols were the major lipids in fruits and flowers. As regards aerial leaves and stems, neutral lipids constituted the main fraction, although significant amounts of galactolipids were also present. Among phospholipids, phosphatidylethanolamine predominated over phosphatidylcholine in all the tissues, especially stems and roots. Alpha linolenic acid was found to be the main component of glycolipids in submerged and aerial leaves; it was also an important constituent of neutral lipids and phospholipids. In relation to the other tissues, linoleic acid was the predominant acid which was stored in stem and root phospholipids and in fruit and flower neutral lipids. Galactolipids in submerged leaves and stems, triacylglycerols in stems and roots and phosphatidylethanolamine in submerged leaves, stems and roots represented the major lipids showing quantitative changes along the year. The fatty acid unsaturation degree also varied in neutral lipids and phospholipids, being higher in winter. Due to the high content of essential fatty acids and their wide distribution in lipids and tissues, M. quitense may be considered for animal nutrition.

Changes of ergosterol content and resistance of population upon drying-rehydration of the yeast Saccharomyces cerevisiae

An investigation was made of changes in ergosterol content of the yeast Saccharomyces cerevisiae upon drying and subsequent rehydration. It was established that drying increases, but rehydration diminishes ergosterol content in yeasts. A statistically reliable multiple correlation was established between the resistance of population to drying, decrease of ergosterol content and a diminishing degree of fatty acid unsaturation during dehydration of dry yeasts.

Phospholiphase A 2 dependent release of fatty acids from peroxidized membranes

Unilamellar vesicles (liposomes) consisting of liver phosphatidylcholine and phosphatidylethanolamine were used as model membranes and subjected to lipid peroxidation. Following peroxidation samples were treated with phospholipase A 2 from snake venom and subsequently analyzed for products of lipid peroxidation and of phospholidase A 2 action. A significantly increased susceptibility to phospholipase A 2 was noted for liposomes subjected to peroxidation, as compared to controls, which correlated with the extent of lipid peroxidation measured by the formation of thiobarbituric acid reacting products and conjugated dienes. Low levels of peroxides were detected in control liposomes and these peroxides were rapidly cleaved by phospholipase A 2, such that nearly 40% of the total peroxide content was associated with free fatty acids after 15 min incubation. Oxidized liposomes contained over seven fold the level of lipid peroxidation products, and these were also rapidly cleaved by phospholipase A 2 where over 50% were recovered as free fatty acids following 15 min of exposure to phospholipase A 2. Along with this high order of removal of oxidized fatty acids, a marked hydrolysis of intact fatty acids was also observed. The extent of fatty acid release was roughly correlated with the degree of fatty acid unsaturation. A substantial increase in the release of arachidonic acid was found when peroxidized membranes were analyzed.

Membrane regulation of liver and lung microsomes under low oxygen tension

A highly monitorized animal model has been developed for the study of the influence of low oxygen tension on lipid composition, microviscosity and regulation of enzyme activities involved in the phospholipid synthesis of hepatic and pulmonary microsomes. Microviscosity decreased in liver microsomes whereas no difference was shown in that of microsomal membrane core of hypoxemic lung. Nevertheless, phospholipid and cholesterol content of both liver and lung membranes changed significantly. Microsomal membranes of hypoxemic liver increased the unsaturation degree of fatty acids, whereas hypoxemic lung membranes become more saturated, mainly due to the increase of palmitic acid. The adaptive response of lung was confirmed by the high increase of the deacylation-reacylation mechanism.

Involvement of Plasma Membrane Alterations in Cold Acclimation of Winter Rye Seedlings (Secale cereale L. cv Puma)

Using plasma membranes with high purity isolated from winter rye seedlings (Secale cereale L. cv Puma) by an aqueous two-polymer phase partition technique, lipid and protein changes were determined during the development of cold hardiness.The degree of fatty acid unsaturation and proportions of phospholipid classes changed only slightly during cold acclimation. A small change, however, was observed in sterol composition; beta-sitosterol increased gradually with a corresponding decrease in campesterol plus stigmasterol during cold acclimation. The phospholipid to protein ratio increased proportionally to the increase in cold hardiness. During the period of acclimation, the sterol to phospholipid ratio declined and was inversely related to the development of cold hardiness.A distinct difference between polypeptide components of nonacclimated and acclimated plasma membrane was observed on two-dimensional sodium dodecyl sulfate slab polyacrylamide gels. A change was also detected in glycopeptides. These results suggest that the plasma membrane is in a dynamic state during cold acclimation, changing in response to the development of cold hardiness.

Lipid composition, physical state, and lipid peroxidation of tumor membranes.

Studies were carried out on microsomes isolated from the highly differentiated (slow-growing) Morris hepatoma 9618A, on microsomes and plasma membranes from the poorly differentiated (fast-growing) Morris hepatoma 3924A, and rat liver used as control. The lipid composition (phospholipid and cholesterol content, degree of fatty acid unsaturation) and peroxidation of such membranes has been correlated with the order and fluidity of the membrane bilayer. The results indicate that substrate availability is the rate-limiting step in microsomal and plasma membrane lipid peroxidation of hepatoma 3924A. From diphenylhexatriene fluorescence depolarization measurements it appears that the changes in lipid composition cause an increase in the order of the lipid bilayer on going from the control to hepatoma 9618A and 3924A microsomes, while fluidity is virtually unchanged. Conversely, for similar chemical changes, in plasma membranes from hepatoma 3924A the order is nearly the same and there is a decrease in fluidity. The changes in the above parameters of tumor membranes might be partly related to the loss of protective enzymes against oxygen radicals. This is supported by the observation that inhibition of liver superoxide dismutase and glutathione reductase, by treatment of rats with diethyldithiocarbamate and chloroethyl nitrosourea, respectively, renders the microsomal membranes more resistant to lipid peroxidation in vitro.

Protein and Lipid Compositions of Isolated Plasma Membranes from Orchard Grass (Dactylis glomerata L.) and Changes during Cold Acclimation

The chemical composition of plasma membrane fractions isolated from orchard grass seedlings (Dactylis glomerata L.) was analyzed and compared with endomembranes. The plasma membrane is characterized by an enrichment of sterols and a lower degree of unsaturation of phospholipids. Steryl glycosides were found to be one of the lipid components of the plasma membrane, but steryl esters and galactolipids were barely detectable. Diphosphatidyl glycerol was characteristically detected in the mitochondrial membrane, but not in the plasma membrane fraction. Plasma mambrane fraction was also characterized by its ;lower fluidity' in comparison with the endomembranes. This may be due to the large amount of sterols and the lower degree of phospholipid unsaturation in plasma membranes.Electrophoretic comparison of polypeptides was also made between different membranes. The distribution patterns of polypeptides revealed on one- and two-dimensional SDS-slab gels were characteristic for those membranes. The presence of glycopeptide complements was a useful criterion for distinguishing plasma membrane from other membranes. The plasma membrane and the ER + Golgi membranes were enriched in glycopeptides. However, a marked difference was revealed in the total number and the molecular weights of the peptides.During cold acclimation of orchard grass seedlings, the degree of fatty acid unsaturation increased only slightly in plasma membrane, unlike in endomembranes. The change in sterols-to-phospholipids ratio in plasma membrane was also slight. On the other hand, the phospholipid-to-protein ratio increased significantly in the plasma membrane as cold hardiness increased. A significant change in the polypeptide complements of plasma membrane was also demonstrated during cold acclimation.

Fatty acid composition during rapid low-temperature induced cold acclimation of Cornus sericea

Dogwood ( Cornus sericea L.) leaves and stems rapidly increased in freezing tolerance during 24 h following transfer from 25/20°C day/night (WT) to 2/2°C day/night (LT). Increases in hardiness continued at a slower rate during the next 6 days of LT exposure. The increase in hardiness during LT exposure was not related to fatty acid composition or degree of fatty acid unsaturation. Fatty acid composition of leaves did not change following transfer from WT to LT over a 7-day period. Linoleic acid accumulated in stem cortical tissue during the 7-day LT-exposure. The elevation of linoleic acid content at LT resulted in an increase in the overall degree of unsaturation in the stem cortical tissue.

Lipid composition of the entomopathogenic fungus Nomuraea rileyi

The total lipid content, neutral and polar lipid composition, and fatty acid profiles were determined for the different developmental stages of the entomopathogenic fungus, Nomuraea rileyi. In general, the lipid composition of N. rileyi was found to be very similar to that of other Fungi Imperfecti. Triacylglycerides and sterols were the major neutral lipids and phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were the major polar lipids. Phosphatidylcholine, resolved in conidial and mycelial samples, was not detected in hyphal body samples. The major fatty acids were palmitic, oleic, and linoleic. Stearic acid was detected as a minor component of hyphal body samples. During conidiogenesis the overall lipid composition was altered in (1) a reduction in total lipid content, (2) an increase in the polar/neutral lipid ratio, and (3) an increase in the degree of fatty acid unsaturation.

Changes in Leaf and Thylakoid Membrane Lipids during Low-Temperature Adaptation of Winter Barley (Hordeum vulgare L.)

Frost-resistant winter cereals actively adapt the fluidity of their membranes to decreasing temperatures. We have attempted to study the membrane lipid changes that are responsible for this adaptation. In the total leaf lipids of winter barley plants (Hordeum vulgare L.) 3 weeks' growth at low temperature (4 °C) decreased the number of double bonds per lipid molecule in all lipid classes extracted from leaves. However, there were only minor changes in the degree of fatty acid unsaturation in the lipids of barley thylakoid membranes during this treatment. In contrast, a significant increase in the lipid/protein ratio was observed in cold-adapted thylakoids when compared with control plants. This cold-induced increase in the lipid/protein ratio seems to act as an adaptive mechanism to maintain fluid membranes despite lower growth temperatures. Cold-hardening also caused a marked increase of the total polar lipids of leaves relative to chlorophyll; this was particularly pronounced for the phospholipids, indicating that the adaptation to low growth temperatures could also be associated with accumulation of extra-chloroplastic material in the cells. © 1984 Oxford University Press.

Modulation of membrane fluidity by catalytic hydrogenation affects the chilling susceptibility of the blue-green alga, Anacystis nidulans

All the changes, i.e. the phase separation temperature of thylakoid lipids, shift in the chilling induced increase of K + permeability and decline in photosynthetic O 2-production, respectively, brought about by temperature acclimation in Anacystis nidulans, can be accomplished by homogeneous catalytic hydrogenation of the fatty acids, as well, using a new water-soluble Pd(II) complex, hitherto unknown in biological applications. Since the thermo-adaptation replaced by proper hydrogenation conducted under isothermal condition results in a similar modification of chilling susceptibility, it afforts direct evidence that chilling response is mediated by changing the degree of fatty acid unsaturation in Anacystis nidulans.