Bounds of change in unsaturation index of fatty acid composition of phospholipids at adaptation of molluscs to biogenic and abiogenic factors of external medium

Comparative study of fatty acid composition of total phospholipids, as well as of phosphatidylcholine and phosphatidylethanolamine from hepatopancreas and leg muscle was performed on several representatives of gasteropods (Gastropoda) molluscs and bivalve (Bivalvia) mussel (Mytilus edulus). The objects of our study were marine litorins (Littorina saxsatilis) adapted to different temperature conditions of White Sea and Barents Sea, freshwater lymnaea (Lymnaea stagnalis) infested by Trematoda and mussels from White Sea and Black Sea. It was shown that depending on the existence conditions of studied tissue or lipid, the maximal change is observed in the percentage of saturated acids (4-83 %), the percentage of unsaturated acids was less expressed (1-14 %) and the changes in unsaturation index (UI) did not exceed 20 % on average. It was supposed that observed quantitative bounds of UI change under the action of different external factors is utmost for maintenance of membrane fluidity necessary for normal vital activity of cell, particularly in studied ectothermic molluscs.     

Effect of habitat and motor activity of molluscs on fatty acid composition of triglycerides and phospholipids

A comparative analysis of fatty acids (FA) in neutral lipids and phospholipids of digestive gland and pedal muscle has been performed in molluscs from various ecological groups differing by belonging to sea or fresh water, trophic types or the associated motor activity. In freshwater pulmonary gastropods Lymnaea stagnalis and Lymnaea ovalis and marine prosobranchial molluscs Buccinum undatum and Littorina littorea the total content of ω3-acids in phospholipids of the studied tissues differed more than twice, predominantly due to the combined effect of temperature and salinity of the habitat. The lower viscosity of cell membranes in marine species (ω3/ω6 < 1) is determined to the greatest degree by the presence of eicosapentaenoic acid that accounts for 22–25% of the FA sum in marine species. Comparison of the molluscs by their trophic belonging has revealed the presence of linoleic acid in triglycerides in digestive glands of phytophages (8–12%), but the practically complete absence of this acid in the predator B. undulatum (< 0.8%). By mobility, L. littorea inhabiting the high-low tide littoral was inferior to freshwater pulmonary gastropods and to the marine predator, as it stops moving twice a day during the low tide. In phospholipids of pedal muscle of this mollusc the amount of long-chain polyunsaturated C: 22 FA was 3–6 times lower than that in other studied species, which might possibly indicate the role of these acids in functioning of the pedal muscle contractile tissue. On the whole, use of the FA characteristics as the parameters determining belonging to certain ecological group requires a certain caution due to a complex action of biotic and abiotic factors on the animal metabolism. The exception is the ω3/ω6 ratio in total phospholipids of fresh water and marine gastropods.     

Analysis of interspecific variation in relative fatty acid composition: use of flow cytometry to estimate unsaturation index and relative polyunsaturated fatty acid content in microalgae

Relative polyunsaturated fatty acid content and unsaturation index are very important composition variables in the use of microalgae both for animal and human nutrition and biofuel production. A readily available technique to rapidly and inexpensively estimate relative fatty acid composition is very important for mass screening of new strains for the production of different types of oil. This study demonstrates the validity of Nile Red staining and flow cytometry for quick estimation of unsaturation index and relative fatty acid content in microalgae. Nile Red staining allows polar and neutral lipid contents to be estimated, and in this study a significant correlation was observed between polar/neutral ratio and fatty acid content in the species studied, corresponding to higher polyunsaturated fatty acid content in the polar lipid fraction of microalgae. This technique enables quick estimation of relative polyunsaturated fatty acid content and interspecific variation, as well as variations caused by culture conditions. In the species studied, most variability in fatty acid composition was due to variation in monounsaturated and polyunsaturated fatty acids, with less variation observed in saturated fatty acid content.     

Human fetal and adult spleen phospholipids and their fatty acid composition

Total phospholipid contents and the individual phospholipid components of human adult and fetal spleens from 17--18 and 23--24 week's pregnancies composition of sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, diphosphatidylglycerol and phosphatidic acid studied in human adult, 17--18 and 23--24 week fetal spleens.     

The influence of fatty acid unsaturation and physical properties of microsomal membrane phospholipids on UDP-glucuronyltransferase activity.

The relationship between lipid composition, the physical properties of microsomal phospholipids and the kinetics of liver UDP-glucuronyltransferase was studied in microsomes from guinea pigs supplied with a normal or a fat-free diet for 28 days. Fatty acid deficiency did not modify either the cholesterol/phospholipid molar ratio or the polar head group composition, but exclusively redistributed the unsaturated fatty acid pattern, by partially exchanging oleic for linoleic acid. This phenomenon accounts for the decrease of both rotational and translational mobilities of the fluorescent probes 1,6-diphenyl-1,3,5-hexatriene (DPH) and pyrene respectively. When the thermotropic behaviour of the different systems was assessed, no transition temperature (gel-liquid-crystalline) between 10 and 40 degrees C was seen as a consequence of the lower degree of unsaturation, either in the microsomal membranes or in the total lipid or total phospholipid extracts from the treated animals. In spite of this, the polarization ratio of trans-parinaric acid and the fluorescence intensity of merocyanine 540 revealed that a significant lateral phase separation occurred at 20-22 degrees C in the extracted phospholipids, which was smoother in the total lipid fractions and in the native microsomal membranes. Fatty acid deficiency caused an upward shift of the midpoint temperature of the lateral phase separation. Furthermore, the phosphatidylcholine extracted from the 'normal' microsomes showed a lateral phase separation centred at a lower temperature than that extracted from 'fat-deficient' microsomes. In contrast, the Arrhenius plot of UDP-glucuronyltransferase from 'normal' microsomes exhibited a change in slope at a higher temperature than that from treated microsomes. These results would suggest that fatty acid deficiency in guinea-pig liver microsomes, while rigidizing the bulk lipids, would segregate the most unsaturated phosphatidylcholine molecules towards the UDP-glucuronyltransferase microenvironment, in accordance with our previous results with cholesterol incorporation [Castuma & Brenner (1986) Biochemistry 25, 4733-4738].     

Changes in fatty acid composition of sulfolipid and phospholipids during maturation of alfalfa

Lipids were extracted from alfalfa samples collected at intervals over the growing season and were fractionated to yield pure sulfolipid. In the sulfolipid and in a phospholipid fraction the major fatty acids were palmitic, linolenic, and linoleic, of which the palmitic acid increased in proportion during the season while the proportion of linolenic acid dropped. The sulfolipid contained more linolenic acid and less palmitic and linoleic acids than the phospholipids, and had a greater rate of change of fatty acid composition.     

Influence of ethanol on fatty acid composition of phospholipids in cultured neurons

Animals chronically exposed to ethanol show changes in neural membrane lipids which may underlie the development of tolerance and physical dependence. The object of this study was to investigate changes in the fatty acid composition of neuronal phospholipids cultured in the presence of ethanol (55 or 110 mM) for periods up to 7 days. Decreases were observed in the percentage of individual and total saturated fatty acids, while the double bond index: total saturated fatty acid ratio, increased. These changes do not support the hypothesis that neural membrane lipid composition changes to counteract the fluidizing action of ethanol.     

Altered fatty acid composition of lung surfactant phospholipids in interstitial lung disease

Deterioration of pulmonary surfactant function has been reported in interstitial lung disease; however, the molecular basis is presently unclear. We analyzed fatty acid (FA) profiles of several surfactant phospholipid classes isolated from large-surfactant aggregates of patients with idiopathic pulmonary fibrosis (IPF; n = 12), hypersensitivity pneumonitis (n = 5), and sarcoidosis (n = 12). Eight healthy individuals served as controls. The relative content of palmitic acid in phosphatidylcholine was significantly reduced in IPF (66.8 +/- 2.5%; means +/- SE; P < 0.01) but not in hypersensitivity pneumonitis (78.5 +/- 1.8%) and sarcoidosis (78.2 +/- 3.1%; control 80.1 +/- 0.7%). In addition, the phosphatidylglycerol FA profile was significantly altered in the IPF patients, with a lower relative content of its major FA, oleic acid, at the expense of saturated FA. In the phosphatidylcholine class, a significant correlation between the impairment of biophysical surfactant function and decreased percentages of palmitic acid was noted. We conclude that significant alterations in the FA profile of pulmonary surfactant phospholipids occur predominantly in IPF and may contribute to the disturbances of alveolar surface activity in this disease.     

Changes in the fatty acid composition of phospholipids from turbot (Scophthalmus maximus) in relation to dietary polyunsaturated fatty acid deficiencies

Young turbot (1-20 g) were maintained for not less than 14 weeks on three diets: (1) a control diet containing normal amounts of polyunsaturated fatty acids (PUFA); (2) a diet totally deficient in PUFA; (3) a diet deficient in the (n-6) series of PUFA but containing (n-3) PUFA. At 14 weeks the fatty acid compositions of the phospholipids from liver, gut, gills and muscle were analysed. Large changes in the amounts of PUFA in the phospholipids were found. Fish maintained on the totally PUFA deficient diet 2 had retained arachidonic acid, 20:4(n-6), and docosahexaenoic acid, 22:6(n-3), at the expense of eicosapentaenoic acid, 20:5(n-3). Fish maintained on the (n-6) PUFA-deficient diet (3) contained decreased amounts of 20:4(n-6) and 22:6(n-3) while retaining 20:5(n-3). In all cases phosphatidylinositol had the lowest n-3/n-6 ratios. These results are discussed in terms of PUFA function.     

Phospholipid composition and fatty acid patterns of isolated phospholipids from rabbit reticulocyte mitochondria

The phospholipid composition and fatty acid patterns of individual phospholipid classes were determined in mitochondria from rabbit reticulocytes. Compared to mitochondria from rat liver reticulocyte, mitochondria exhibit about twice the amount of phospholipids. The phospholipid pattern of reticulocyte mitochondria (phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and cardiolipin) is comparable with other mitochondrial species. Mitochondrial fractions from reticulocytes are characterized, however, by an additional content of sphingomyelin. This sphingomyelin differs in its fatty acid composition from the sphingomyelin of the plasma membrane. The fatty acid patterns of all other phospholipids essentially correspond to those of mitochondria from other sources and to those of plasma membranes as well.     

Dietary fatty acid composition changes mitochondrial phospholipids and oxidative capacities in rainbow trout red muscle

Dietary conditioning of juvenile trout changed the acyl chain composition of mitochondrial phospholipids and the oxidative capacities of muscle mitochondria. Trout were fed three diets differing only in fatty acid (FA) composition. The highly unsaturated 22:6 n-3 (DHA) accounted for 0.4, 14, and 30% of fatty acids in Diets 1, 2 and 3. After 10 weeks of growth, the dietary groups differed markedly in FA composition of mitochondrial phospholipids, with significant dietary effects for virtually all FA. Mean mitochondrial DHA levels were 19, 40 and 33% in trout fed Diets 1, 2 and 3. Mitochondrial oxidative capacities changed with diet, while mitochondrial concentrations of cytochromes and of the adenylate nucleotide translocase (nmol mg¹ protein) did not. Mitochondria from fish fed Diet 1 had higher non-phosphorylating (state 4) rates at 5°C than those fed other diets. When phosphorylating (state 3) rates differed between dietary groups, rates at 5 and 15°C were higher for fish fed the more unsaturated diets. Stepwise multiple regressions indicated that FA composition could explain much (42–70%) of the variability of state 4 rates, particularly at 5°C. At 15°C, FA composition explained 16–42% of the variability of states 3 and 4 rates. Similar conclusions were obtained for the complete data set (trout fed diets 1, 2 and 3) and for the data from trout achieving similar growth rates (e.g. those fed Diets 1 and 2). Neither general characteristics of membrane FA, such as % saturates, unsaturation index, n-3, n-6 or n-3/n-6 nor levels of abundant unsaturated FA such as DHA or 18:1(n-9 + n-7), were systematically correlated with mitochondrial capacities even though they differed considerably between trout fed the different diets. Relatively minor FA (20:5n-3, 20:0, 18:2n-6, 18:3n-3, 18:0 and 15:0) showed better correlations with mitochondrial oxidative capacities. This supports the concept that acyl chain composition modulates mitochondrial capacities via interactions between membrane proteins and specific FA of particular phospholipid classes in their microenvironment.     

Effect of diazepam on the fatty acid composition of plasma and liver phospholipids in rat.

Male Wistar rats (2 months old) were maintained on a nutritionally adequate diet, and diazepam was administered at a dose of 10 mg/kg/day. After 24 weeks the effects on the fatty acid composition of plasma and liver phospholipids were studied. Increased levels of palmitic (16:0), palmitoleic (16:1n-7), stearic (18:0), and oleic (18:1n-9) acids were found in plasma phospholipids. In contrast, the levels of docosapentanoic (22:5n-3) and docosahexanoic (22:6n-3; DHA) acids were drastically decreased by diazepam. A significant decrease produced by diazepam was also found in levels of DHA in liver phospholipids.     

Changes in fatty acid composition of phospholipids and triacylglycerols after cold-acclimation of an aestivating insect prepupa

Prepupae of the Mediterranean arctiid moth Cymbalophora pudica spend hot spring and summer months in a summer diapause (aestivation). Although their cold-hardiness (survival after 1-day exposure to subzero temperatures) is relatively low, it may be moderately enhanced by prior cold acclimation at decreasing above-zero temperatures. In this study, fatty acids of phospholipids and triacylglycerols were analysed in five different tissues (body wall, midgut, fat body, silk glands and brain) dissected from both cold-acclimated and control aestivating prepupae. The five most abundant fatty acids (oleic, palmitic, stearic, linoleic and α-linolenic), found generally in both lipidic fractions and all five tissues, represent a typical fatty complement of Lepidoptera. The fatty acid profiles of individual tissues differed from each other and the response to cold acclimation was also tissue-specific. Moderate but significant increases in the proportion of unsaturated fatty acids after cold acclimation were observed in triacylglycerols of the body wall, fat body and silk glands. Additionally, significant rearrangements of fatty acid profiles were found in triacylglycerols of midgut and brain, without changing the unsaturation/saturation ratio. The adaptational value of enhanced fluidity of fat body triacylglycerols caused by their increased unsaturation remains unclear, because the lipidic energy depots are not utilized during aestivation of this insect. Minimal capacity to alter the membrane-bound fatty acids was found in all tissues except midgut, where the unsaturation/saturation ratio of phospholipids slightly increased after cold acclimation. A low ability to alter the composition of membrane lipids in response to low temperature, correlates well with the low capacity of C. pudica prepupae to enhance their cold-hardiness during cold-acclimation. This may be regarded as indirect support for the membrane lipid restructuring in insect cold adaptation. Accepted: 11 May 1998     

Ontogenetic change in the lipid and fatty acid composition of scleractinian coral larvae

Some scleractinian coral larvae have an extraordinary capacity to delay metamorphosis, and this is reflected in the large geographic range of many species. Coral eggs typically contain a high proportion of wax esters, which have been hypothesized to provide a source of energy for long-distance dispersal. To better understand the role of lipids in the dispersal of broadcast spawning coral larvae, ontogenetic changes in the lipid and fatty acid composition of Goniastrea retiformis were measured from the eggs until larvae were 30 days old. Egg biomass was 78.8 ± 0.5% lipids, 86.3 ± 0.2% of which were wax esters, 9.3 ± 0.0% polar lipids, 4.1 ± 0.2% sterols, and 0.3 ± 0.1% triacylglycerols. The biomass of wax esters declined significantly through time, while polar lipids, sterols and triacylglycerols remained relatively constant, suggesting that wax esters are the prime source of energy for development. The most prevalent fatty acid in the eggs was palmitic acid, a marker of the dinoflagellate Symbiodinium, highlighting the importance of symbiosis in coral reproductive ecology. The proportion of polyunsaturated fatty acids declined through time, suggesting that they are essential for larval development. Interestingly, triacylglycerols are only abundant in the propagules that contain Symbiodinium, suggesting important differences in the energetic of dispersal among species with vertical and horizontal transmission of symbionts.     

Thermal regulation of the fatty acid composition of lipopolysaccharides and phospholipids of Proteus mirabilis.

The fatty acid composition of the lipid A moiety of the lipopolysaccharide and phospholipid fractions of Proteus mirabilis changed significantly on varying the growth temperature. A decrease in the growth temperature from 43 degrees C to 15 degrees C resulted in a decrease in the palmitic acid content of the lipopolysaccharide from 19.4% of total fatty acids at 43 degrees C to 1.4% at 15 degrees C, and by the appearance of an unsaturated fatty acid residue, hexadecenoic acid. Changes in the 3-hydroxy-myristic acid content of the lipid A were minimal. The decrease in the growth temperature also resulted in a decrease in the saturated fatty acid content of the phospholipid fraction, which was accompanied by an increase in their fluidity, as measured by the freedom of motion of spin-labeled fatty acids incorporated into dispersions made of the phospholipids. Nevertheless, the fluidity obtained with membrane phospholipids extracted from the cells grown at various temperatures were essentially the same when fluidity was determined at the growth temperature, supporting the hypothesis that variations in the fatty acid composition of membrane phospholipids serve to produce membranes having a constant fluidity at different temperatures of growth.     

Changes in the fatty acid composition of pulmonary surfactant phospholipids after administration of antitubercular agents

The prolonged inhalations of streptomycin sulphate and isoniazid in experiments on rats decrease the content of unsaturated fatty acids and increase that of saturated ones in the phospholipids composition of lungs surfactants.