Changes produced by trematode larvae in the phospholipid fatty acid composition of digestive gland of the mollusc Littorina saxatilis

Lipids of the digestive gland of the mollusc Littorina saxatilis from the White and Barents Seas were studied. Changes of its biochemical composition are discussed in the connection with different temperature of the habitat and with infestation with trematode larvae. Comparative analysis of the fatty acid (FA) composition of each of phospholipids in intact molluscs has revealed essential differences. Phosphatidylcholine and monophosphatidylinositol (MPI) FA did not differ in the omega 3/omega 6 ratio, which is due to their tolerance to the temperature factor, whereas more unsaturated phospholipids--phosphatidylethanolamine (FEA), its plasmalogen form (pFEA), and phosphatidylserine--differed 1.5-2 times in the studied molluscs. Predominance of omega 3 acids in the Borents Sea molluscs undoubtedly is due to the lower habitat temperatures, as it provides a higher fluidity of membrane phospholipids. Infestation affected to the greatest degree the quantitative FA composition in pFEA and MPI. At infestation, out of all considered phospholipids, only in MPI there was revealed a threefold decrease of the content of eikosenoic acid C20 : 1, whereas in all other phospholipids, in the contrary, it increased. Monophosphatidylinositols also differed essentially from other phospholipids by the saturated FA amount, which changed the unsaturation index of these phospholipids. Since the functional significance of this minor phospholipid is determined by its participation in the so-called phosphatidylinositol system of the hormonal signal transduction, it seems interesting to elucidate whether an increase of this membrane phospholipid saturation at invasion affects the reflex connection between signals from receptors located in a parasite and enzymatic processes.     

Changes of phospholipid fatty acid composition in the digestive gland of the mollusc <Emphasis Type="Italic">Littorina saxatilis</Emphasis>, caused by trematode larvae

Lipids in the digestive gland of the mollusc Littorina saxatilis from the White and Barents Seas were studied. Changes of their biochemical composition are discussed in the connection with different temperature of the habitat and with infestation with trematode larvae. Comparative analysis of the fatty acid (FA) composition of each of the phospholipids in intact molluscs has revealed essential differences. Phosphatidylcholine and monophosphatidylinositol (MPI) FA did not differ in the ω3/ω6 ratio, which is due to their tolerance to the temperature factor, whereas more unsaturated phospholipids—phosphatidylethanolamine (PEA), its plasmalogen form (pPEA), and phosphatidylserine—differed 1.5–2 times in the studied molluscs. Prevalence of ω3-acids in Barents Sea mollusc is associated undoubtedly with lower habitat temperatures, as this provides a higher fluidity of the membrane phospholipids. Infestation affected to the greatest degree the quantitative FA composition in pPEA and MPI. At infestation, there was revealed a threefold decrease of the content of eicosenoic FA, C20:1, only in MPI among all considered phospholipids, whereas it was increased, in the contrary, in all other phospholipids. Monophosphatidylinositols differed essentially from other phospholipids by the saturated FA amount as well, which changed the unsaturation index of these phospholipids. Since the functional significance of this minor phospholipid is determined by its participation in the so-called phosphatidylinositol system of the hormonal signal transduction, it seems interesting to elucidate whether the increase of this membrane phospholipid saturation at invasion affects the reflex connection between signals from receptors located in the parasite and enzymatic processes.     

Phospholipid and triacylglycerol fatty acid content and pattern in the cardiac endothelium of rats depleted in long-chain polyunsaturated omega 3 fatty acids

Rats depleted in long-chain polyunsaturated omega3 fatty acids (omega3-depleted rats) display several features of the metabolic syndrome including hypertension and cardiac hypertrophy. This coincides with alteration of the cardiac muscle phospholipid and triacylglycerol fatty acid content and/or pattern. In the present study, the latter variables were measured in the cardiac endothelium of normal and omega3-depleted rats. Samples derived from four rats each were obtained from 16 female normal fed rats and three groups of 36-40 female fed omega3-depleted rats each aged 8-9, 15-16 and 22-23 weeks. At comparable mean age, the ratio between the square root of the total fatty acid content of phospholipids and cubic root of the total fatty acid content of triacylglycerols was lower in omega3-depleted rats than in control animals. The total fatty acid content of triacylglycerols was inversely related to their relative content in C20:4omega6. Other differences between omega3-depleted rats and control animals consisted in a lower content of long-chain polyunsaturated omega3 fatty acids in both phospholipids and triacylglycerols, higher content of long-chain polyunsaturated omega6 fatty acids in phospholipids, higher activity of delta9-desaturase (C16:0/C16:1omega7 and C18:0/C18:1omega9 ratios) and elongase [(C16:0 + C16:1omega7)/(C18:0 + C18:1omega9) and C20:4omega6/C22:4omega6 ratios], but impaired generation of C22:6omega3 from C22:5omega3 in the former rats. These findings support the view that cardiovascular perturbations previously documented in the omega3-depleted rats may involve impaired heart endothelial function.     

Lipidomics of hepatic lipogenesis inhibition by omega 3 fatty acids

We assessed – by a lipidomic approach – the differential incorporation of EPA and DHA into hepatic lipids, after prolonged feeding of rats with fish oil. We also evaluated their effect on lipogenesis and its related enzymes. Rats were administered 100 mg/kg/d fish oil, by oral gavage, for 30 days. The fatty acid profile of total liver lipids was determined by gas–liquid chromatography coupled to mass spectrometry. Individual phospholipid classes and their molecular species were quantified by ESI-MS/MS. Omega 3 fatty acids readily incorporated into hepatic phospholipids, decreased stearoyl-CoA desaturase 16, stearoyl-CoA desaturase, delta 6 desaturase, and delta 5 desaturase activities (calculated as product/substrate ratio) and decreased the “lipogenesis index”, i.e., the proportion of fatty acids endogenously synthesized in the liver and not provided with the diet. Our results show that long-chain omega 3 fatty acids selectively incorporate into hepatic phospholipids, inhibit de novo lipogenesis and change the hepatic fatty acid profile via reduced desaturases' activity in the non-steatotic liver. In addition to corroborating advice to consume adequate amounts of omega 3 fatty acids for overall health, these data contribute mechanistic insights to the clinical observations that provision of omega 3 fatty acids decreases hepatic fat and ameliorates NAFLD prognosis.     

Accelerated clearance of plasma triglycerides and free fatty acids in omega3-depleted rats.

The present study aims mainly at exploring the effects of a severe depletion in polyunsaturated long-chain omega3 fatty acids upon the fate of circulating lipids. The plasma concentration and fatty acid pattern of triglycerides, diglycerides, free fatty acids, and phospholipids were measured in omega3-depleted and control rats injected intravenously one hour before sacrifice with either saline, a control medium-chain triglyceride:olive oil emulsion or a medium-chain triglyceride:fish oil emulsion recently found to rapidly increase the phospholipid content of C20:5omega3 and C22:6omega3 in different cell types. The estimated fractional removal rate of the injected triglycerides and the clearance of free fatty acids from circulation were both higher in omega3-depleted rats than in control animals. The injection of the lipid emulsions apparently inhibited intracellular lipolysis, this being least pronounced in omega3-depleted rats. The increased clearance of circulating triglycerides and unesterified fatty acids in omega3-depleted rats may favor the cellular accumulation of lipids. In turn, such an accumulation and the lesser regulatory inhibition of tissular lipolysis may match the increased clearance of circulating unesterified fatty acids and, hence, account for the lack of any significant difference in plasma unesterified fatty acid concentration between these and control animals.     

Fatty acid composition of human milk in Kuwaiti mothers

Kuwaiti diet is exceptionally rich in fat, carbohydrates and proteins. In addition, subjects in Kuwait are exposed to extreme heat and sun light. Fatty acid profiles of human milk obtained from 19 full breast feeding Kuwaiti mothers were analyzed. Dietary patterns for individual mothers were determined by 24 h dietary recall and food frequency questionnaire. The fatty acid content of human milk was affected by the diet consumed by the lactating mother. The content of long chain polyunsaturated fatty acids (LCP) in human milk lipids did not correlate with their parent fatty acids like linoleic and alpha-linolenic acids. However the human milk LCP were related to the of content of LCP in the maternal diet. Mothers reporting a high fish consumption showed significant amounts of C22:6, omega 3 and C20:5, omega 3 fatty acids. As a general conclusion, breast milk produced by a well nourished mother is better suited to meet the lipid requirements of infants.     

Changes in the lipid composition of embryonic cells of the mussel Mytilus trossulus during cryopreservation

A comparative analysis of the lipid composition of embryonic cells of the mussel Mytilus trossulus prior to, and after, cryopreservation in liquid nitrogen was carried out in the presence of two types of cryoprotectors: 1) dimethylsulfoxide and trehalose; and 2) dimethylsulfoxide, trehalose, total lipid extract from the mussel Crenomytilus grayanus, alpha-tocopherol and ascorbic acid. It was found that not only the cell viability but also the fatty acid composition of cell lipids after cryopreservation depend on the composition of cryoprotectors used. The content of saturated fatty acids, monoenic and polyenic fatty acids, the omega 3/omega 6 ratio, and the index of nonsaturation in the fatty acid composition of lipids was shown to change remarkably after cryopreservation. Possible reasons of these changes are discussed.     

Age and sex characteristics of phospholipid composition of Wistar rat erythrocytes during postnatal ontogenesis

The composition of phospholipids and fatty acids of erythrocyte lipids of intact mature Wistar rats and their progeny in the age of 10, 15, 20, 30, 40, 60, 90 and 110 days was studied with the methods of micro-thin-layer and gas-liquid chromatography. Sex features and age mechanism of erythrocyte lipids composition forming in physiologically standard conditions were established. The fact that the composition of erythrocyte lipids of the untreated grown-up male rats in comparison with the female species is characterised with a lower concentration of phosphatidylinositol, a higher level of phosphatidylcholine and sphingomyelin, a higher saturation level of molecular types of phospholipids, was described. Three age periods of homeostasis of the erythrocyte lipids of the intact rats were distinguished. The postembryonic period (30-40 days after birth) is characterised with forming of the basic pool of erythrocyte lipids: getting to the stability in levels of the basic components of phospholipids and their fatty acids, coming out of phosphatidylinositol by the 40th day after birth. The period of sex-growing (60 days) is accompanied by spasmodic changes in the levels of fatty acids which is most common for female species: rapid increase in saturated and omega 3 polyunsaturated fatty acids, decrease in monoene and omega 6 polyene fatty acids. The period of maturity (110 days) is characterised by a slow metabolism of structural lipids and a stabilisation of their composition.     

Effects of postnatal age and diet on the fatty acid composition of plasma lipid fractions in preterm infants

Diet and postnatal age effect the fatty acid composition of plasma and tissue lipids. This work was designed as a transversal study to evaluate the changes in the fatty acid composition of plasma phospholipids, cholesteryl esters, triglycerides and free fatty acids in preterm infants (28-35 weeks gestational age), fed human milk (HM) and milk formula (MF) from birth to 1 month of life. Sixteen blood samples were obtained from cord, and 19 at 6-8 h after birth, 14 at 1 week and 9 at 4 weeks from HM-fed infants and 18 at 1 week and 14 at 4 weeks from MF-fed ones. Groups had similar mean birth weight, gestational age and sex ratio. The MF provided 69 kcal/dl and contained 16% of linoleic acid and 1.3% of alpha-linolenic acid on the total fat. Plasma lipid fractions were extracted and separated by thin-layer chromatography and fatty acid methyl esters were quantitated by gas liquid chromatography. In plasma phospholipids, linoleic acid (18:2 omega 6) continuously increased from birth to 1 month of age, but no changes were seen as related to type of diet; polyunsaturated fatty acids greater than 18 carbon atoms of both the omega 6 and omega 3 series (PUFA omega 6 greater than 18 C and omega 3 greater than 18 C) dropped from birth to 1 week and continued to decrease in MF-fed infants until 1 month; eicosatrienoic (20:3 omega 6), arachidonic (20:4 omega 6) and docosahexaenoic (22:6 omega 3) were the fatty acids implicated. In cholesteryl esters palmitoleic (16:1 omega 7) and oleic (18:1 omega 9) acids decreased from birth to 1 month and linoleic acid increased and arachidonic acid dropped, especially in MF fed infants. In triglycerides, palmitic, palmitoleic and stearic acid (18:0) decreased during the first month of life; oleic acid remained constant and linoleic acid increased in all infants, but arachidonic acid decreased only in those fed formula. Free fatty acids showed a similar behavior in fatty acids and in plasma triglycerides. Preterm neonates seem to have special requirements of long-chain PUFA and adapted MF should contain these fatty acids in similar amounts to those of HM to allow the maintenance of an adequate tissue structure and physiology.     

Content of prostaglandin biosynthesis precursors in the kidney lipids in the development of spontaneous arterial hypertension

The content of linoleic (18 : 2 omega 6), arachidonic; (20 : 4 omega 6) and eicosatrienic (20 : 3 omega 9) acids was studied and compared in lipids of the renal cortex and papilla of spontaneously hypertensive Okamoto-Aoki rats (SHR) and normotensive Wistar rats (NR) aged 10 days, 1, 2 and 4 months. The level of 18 : 2 omega 6 in lipids of the renal cortex and papilla of SHR was lower at the prehypertensive stage (10 days) and at the stage of persistent hypertension as compared to that seen in NR. The content of 20 : 4 omega 6 in phospholipids and triglycerides of the cortex and in phospholipids of the papilla of SHR did not differ from that in NR. In triglycerides of the papilla of SHR of all age groups, the content of 20 : 4 omega 6 was higher than in NR. In phospholipids of SHR cortex, the content of 20 : 3 omega 9 was higher than that in NR. As for lipids of the papilla, 20 : 3 omega 9 was not detectable either in NR or SHR. It is concluded that the data obtained are of interest for the characteristics of the renal prostaglandin system in SHR.     

The effect of dietary lipids on the thermotropic behaviour of rat liver and heart mitochondrial membrane lipids

Diets supplemented with relatively high levels of either saturated fatty acids derived from sheep kidney fat (sheep kidney fat diet) or unsaturated fatty acids derived from sunflower seed oil (sunflower seed oil diet) were fed to rats for a period of 16 weeks and changes in the thermotropic behaviour of liver and heart mitochondrial lipids were determined by differential scanning calorimetry (DSC). The diets induced similar changes in the fatty acid composition in both liver and heart mitochondrial lipids, the major change being the omega 6 to omega 3 unsaturated fatty acid ratio, which was elevated in mitochondria from animals on the sunflower seed oil diet and lowered with the mitochondria from the sheep kidney fat dietary animals. When examined by DSC, aqueous buffer dispersions of liver and heart mitochondrial lipids exhibited two independent, reversible phase transitions and in some instances a third highly unstable transition. The dietary lipid treatments had their major effect of the temperature at which the lower phase transition occurred, there being an inverse relationship between the transition temperature and the omega 6 to omega 3 unsaturated fatty acid ratio. No significant effect was observed for the temperature of the higher phase transition. These results indicate that certain domains of mitochondrial lipids, probably containing some relatively higher melting-point lipids, independently undergo formation of the solidus or gel phase and this phenomenon is not greatly influenced by the lipid composition of the mitochondrial membranes. Conversely, other domains, representing the bulk of the membrane lipids and which probably contain the relatively lower melting point lipids, undergo solidus phase formation at temperatures which reflect changes in the membrane lipid composition which are in turn, a reflection of the nature of the dietary lipid intake. These lipid phase transitions do not appear to correlate directly with those events considered responsible for the altered Arrhenius kinetics of various mitochondrial membrane-associated enzymes.     

Lipids,amino acids,sugars, hardiness and growth of Festuca arundinacea

Tall fescue (Festuca arundinacea Schreb. cv S.170) plants were grown in environments differing only in temperature: 6/4, 16/14 or 21/19°. The content of total and individual sugars and amino acids in leaf laminae and roots did not relate closely to the hardiness of the organ. The unsaturation of lipid fatty acids alone was clearly unrelated to hardiness because the difference in unsaturation was greater in the neutral lipids, glycolipids and phospholipids from roots than from leaves but only the latter differed in hardiness. Total amounts of lipids could have been related to hardiness but phospholipids and glycolipids in the roots were not. At least some of these changes may be related to adaptation of growth to temperature.     

Effects of dietary omega-6 and omega-3 fatty acids on levels of long chain polyunsaturated fatty acids in erythrocytes]

C18:2 omega 6/C18:3 omega 3 ratio was lowered in the diet of Elderly subjects. This was done by the replacement of usual sunflower oil by rapeseed oil or by supplementing soybean oil. This diet modification induced an increase of EPA (C20:5 omega 3) and DHA (C22:6 omega 3) in red cell phospholipids. The omega 6 fatty acids (C18:2 and C20:4) were slightly modified. Therefore, dietary C18:2 omega 6/C18:3 omega 3 ratio, seems to play an important role in the determination of membrane highly unsaturated fatty acid levels.     

Seasonal variation in lipid and fatty acid composition of ice algae from the Barents Sea

The fatty acid compositions of neutral lipid, glycolipid and phospholipid fractions from ice algae sampled from the Barents Sea in spring and autumn were examined for seasonal differences. The ice-algal assemblages were dominated by diatoms. In spring, Nitzschia frigida was the most common species whereas resting stages of Thalassiosira bioculata and Actinocyclus cf curvatulus predominated in autumn. With the exception of one spring sample, neutral lipids predominated over glycolipids and phospholipids in all algal samples. The lipid fractions displayed characteristic fatty acid compositions. In the spring samples the major fatty acids of the neutral lipid fraction were 16:0, 16:1(n-7) and 20:5(n-3) whilst the glycolipid fraction was characterised by higher levels of 20:5(n-3) and C16 polyunsaturated fatty acids, particularly 16:4(n-1). Phospholipids contained higher levels of 22:6(n-3) than the other two lipid fractions although 20:5(n-3) was still the major polyunsaturated fatty acid. In the autumn samples, the neutral lipid fraction contained higher proportions of saturated fatty acids and 16:1(n-7) than the two polar lipid fractions and 22:6(n-3) was most abundant in phospholipids. As with the spring samples, 20:5(n-3) was the major polyunsaturated fatty acid in all lipid fractions of the autumn algae. Overall, the fatty acid compositions of the lipid fractions from spring and autumn algal samples were similar and are consistent with diatoms being the predominant group in the ice algae studied. The high level of neutral lipids observed in both spring and autumn samples suggests that the production of neutral lipids is characteristic of ice algae regardless of season. Nevertheless, some species-specific differences in lipid production may exist since the neutral lipid content of autumn samples containing mainly A. curvatulus was substantially higher than those in which T. bioculata predominated. Received: 26 September 1997 / Accepted: 12 January 1998     

Seasonal changes of fatty acid composition and thermotropic behavior of polar lipids from marine macrophytes

Major glyco- and phospholipids as well as betaine lipid 1,2-diacylglycero-O-4'-(N,N,N-tri-methyl)-homoserine (DGTS) were isolated from five species of marine macrophytes harvested in the Sea of Japan in summer and winter at seawater temperatures of 20-23 and 3 degrees C, respectively. GC and DSC analysis of lipids revealed a common increase of ratio between n-3 and n-6 polyunsaturated fatty acids (PUFAs) of polar lipids from summer to winter despite their chemotaxonomically different fatty acid (FA) composition. Especially, high level of different n-3 PUFAs was observed in galactolipids in winter. However, the rise in FA unsaturation did not result in the lowering of peak maximum temperature of phase transition of photosynthetic lipids (glycolipids and phosphatidylglycerol (PG)) in contrast to non-photosynthetic ones [phosphatidylcholine (PC) and phosphatidylethanolamine (PE)]. Different thermotropic behavior of these lipid groups was accompanied by higher content of n-6 PUFAs from the sum of n-6 and n-3 PUFAs in PC and PE compared with glycolipids and PG in both seasons. Seasonal changes of DSC transitions and FA composition of DGTS studied for the first time were similar to PC and PE. Thermograms of all polar lipids were characterized by complex profiles and located in a wide temperature range between -130 and 80 degrees C, while the most evident phase separation occurred in PGs in both seasons. Polarizing microscopy combined with DSC has shown that the liquid crystal - isotropic melt transitions of polar lipids from marine macrophytes began from 10 to 30 degrees C mostly, which can cause the thermal sensitivity of plants to superoptimal temperatures in their environment.     

Differential distribution of DHA-phospholipids in rat brain after feeding: A lipidomic approach

On a per-weight basis, the brain is the organ richest in lipids, including a remarkable proportion of polyunsaturated fatty acids (PUFAs) of the omega 3 series, namely eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The cerebral effects of exogenous DHA likely depend on its degree of incorporation into neuronal phospholipids and on its distribution among the various brain structures, after intake. Hence, because PUFAs are not evenly distributed among the brain phospholipid classes and because the existence of class-specific phospholipases that regulate their turnover, we sought to investigate the incorporation of omega 3 PUFAs in selected brain areas regions and specific phospholipid classes. Rats (n=7) were administered, by oral gavage, 100mg/kg/d of a commercially available fish oil (containing ～84% of long-chain omega 3 fatty acids, of which ～38% of DHA and ～46% of EPA). Control rats (n=7) received liquid paraffin. This treatment was continued for 30 days. Thereafter, we dissected three areas, namely the hippocampus, the striatum, and the cortex. Quantization of individual phospholipid classes and their molecular species was performed by ESI-MS/MS. Principal component analysis was used to examine the variation of the molecular lipid profiles (as percentage) induced by omega 3 supplementation. Our results show that provision of omega 3 fatty acids to rats results in their incorporation into brain phospholipids, the extent of which is lower in the striatum as compared with cortex and hippocampus. These data might in part explain the mixed therapeutic results obtained in neurological disorders, many of which are likely region-specific.     

Phosphorus Effects on the Mycelium and Storage Structures of an Arbuscular Mycorrhizal Fungus as Studied in the Soil and Roots by Analysis of Fatty Acid Signatures

The distribution of an arbuscular mycorrhizal (AM) fungus between soil and roots, and between mycelial and storage structures, was studied by use of the fatty acid signature 16:1(omega)5. Increasing the soil phosphorus level resulted in a decrease in the level of the fatty acid 16:1(omega)5 in the soil and roots. A similar decrease was detected by microscopic measurements of root colonization and of the length of AM fungal hyphae in the soil. The fatty acid 16:1(omega)5 was estimated from two types of lipids, phospholipids and neutral lipids, which mainly represent membrane lipids and storage lipids, respectively. The numbers of spores of the AM fungus formed in the soil correlated most closely with neutral lipid fatty acid 16:1(omega)5, whereas the hyphal length in the soil correlated most closely with phospholipid fatty acid 16:1(omega)5. The fungal neutral lipid/phospholipid ratio in the extraradical mycelium was positively correlated with the level of root infection and thus decreased with increasing applications of P. The neutral lipid/phospholipid ratio indicated that at high P levels, less carbon was allocated to storage structures. At all levels of P applied, the major part of the AM fungus was found to be present outside the roots, as estimated from phospholipid fatty acid 16:1(omega)5. The ratio of extraradical biomass/intraradical biomass was not affected by the application of P, except for a decrease at the highest level of P applied.     

Effect of temperature acclimatization on the fatty acid composition of goldfish intestinal lipids

1. The fatty acid composition of whole goldfish, whole-intestinal mucosa, intestinal mucosal membranes and individual phospholipids extracted from mucosal membranes were measured, fish adapted to different temperatures being used. 2. Alterations of the adaptation temperature did not noticeably affect the fatty acid composition of the whole-fish lipids, but there were marked changes in the fatty acids of lipids extracted from homogenates of goldfish intestinal mucosa. These changes were more pronounced in a membrane fraction prepared from these homogenates. Raising the adaptation temperature by 20 degrees C halved the percentage of C(20:1), C(20:4) and C(22:6) fatty acids and nearly doubled the percentage of C(18:0) and C(20:3) fatty acids recovered. 3. Choline phosphoglycerides constituted about one-half and ethanolamine phosphoglycerides about one-quarter of the total membrane phospholipids. 4. The fatty acids of choline and ethanolamine phosphoglycerides were more susceptible to temperature-dependent changes than were the phosphoglycerides of inositol or serine. 5. The increase in C(18:0) fatty acid that occurred in membranes of warm-adapted fish was greatest for ethanolamine phosphoglycerides, but increases also occurred in other phospholipid fractions and in membrane neutral lipids.     

Alteration of adipocyte metabolism in omega3 fatty acid-depleted rats.

Presently an insufficient supply of long-chain polyunsaturated omega3 fatty acid is prevalent in Western populations leading to potential metabolic consequences. Based on this fact, this study deals mainly with various aspects of lipid metabolism in second generation female omega3-depleted rats. The parametrial fat and body weights were higher in omega3-depleted than control animals. This coincided with liver steatosis but did not alter heart triglyceride/phospholipid ratio. The net uptake of [U-14C] palmitate by adipocytes was also higher in omega3-depleted rats than in control animals. The uptake of D-[U- 4C] glucose or [1,2 (-14)C] acetate by adipocytes was lower, however in omega3-depleted than control animals and was unaffected by insulin in the former as distinct from latter animals. Despite comparable basal lipolysis, the increase in glycerol output from adipocytes provoked by theophylline was higher in omega3-depleted than control rats. The fatty acid pattern of lipids in adipose tissue was characterized in the omega3-depleted rats by a much lower omega3 content, higher apparent Delta 9-saturase and elongase activities, lower efficiency for the conversion of C18:2omega6 to C20:4omega6 and higher efficiency for the conversion of C18:3omega3 to C20:5omega3. These features were compared to those prevailing in liver and plasma lipids. The present study thus extends knowledge on the alteration of lipid metabolism resulting from a deficiency in long-chain polyunsaturated omega3 fatty acids.     

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.