Polyunsaturated molecular species of galactolipids: Markers of zooxanthellae in a symbiotic association of the soft coral Capnella sp. (Anthozoa: Alcyonacea)

A method that uses marker fatty acids (FAs) is widely applied in investigations of trophic and symbiotic relationships. In a search for new lipid markers, we determined the total lipid FA composition, as well as the composition of molecular species of mono- and digalactosyl diacylglycerols (MGDGs and DGDGs), which are specific galactolipids of thylakoid membranes, in zooxanthellae (endosymbiotic dinoflagellates) of the tropical soft coral Capnella sp. Some FAs of zooxanthellae were suggested for use as marker polyunsaturated FAs (PUFAs). Thirteen molecular species of MGDGs and ten molecular species of DGDGs were detected using the method of high-resolution tandem mass spectrometry. All marker PUFAs of zooxanthellae were found in acyl groups of galactolipids. The major molecular species of DGDGs (18:4/18:4, 18:4/20:5, and 16:2/22:6) and the unique molecular species of MGDGs (16:4/18:5) were described. The identification of several polyunsaturated molecular species of galactolipids that contain marker FAs allowed us to propose that this lipid group be used as molecular lipid markers of zooxanthellae for the study of symbiont–host interactions in soft corals.     

Light intensity influences the production and translocation of fatty acids by zooxanthellae in the jellyfish Cassiopea sp.

The influence of light intensity on the fatty acid profiles of the scyphozoan jellyfish Cassiopea sp. and its endosymbiotic zooxanthellae was investigated using a manipulative experiment. The aims of the study were to: 1) identify changes related to light intensity in the fatty acid profiles of the host jellyfish and zooxanthellae; 2) determine if jellyfish exposed to low light intensities compensated for reduced rates of photosynthesis by increasing heterotrophic feeding; and 3) determine if concentrations of zooxanthellae and chlorophyll a (chl a) increased in jellyfish exposed to reduced light intensity. Jellyfish were collected from an artificial urban tidal lake in southeast Queensland, Australia. Two were frozen for immediate analysis and 15 were randomly allocated to each of nine mesocosms. Three replicate mesocosms were then randomly allocated to each of three light treatments: 100%, 25%, and 10% PAR. The mesocosms were supplied with unfiltered, continuous flowing seawater and jellyfish fed on natural zooplankton, supplemented with frozen Mysis shrimp. Three jellyfish were sampled, with replacement, from each mesocosm 3, 15, 22, 39 and 69 days after the experiment commenced. Fatty acids as methyl esters in the host tissue (mesoglea) and zooxanthellae were determined separately using gas chromatography and verified by mass spectrometry. The fatty acid profiles of the host jellyfish and zooxanthellae remained unchanged in the 100% PAR treatment throughout the experiment but varied in the lower light treatments. A decrease in light intensity caused a reduction in the concentrations of some polyunsaturated fatty acids such as 18:1ω9 and 18:4ω3 in the zooxanthellae, the latter being abundant in dinoflagellates. Concomitantly, the concentrations of these fatty acids increased in the host tissues, suggesting a possible transfer of zooxanthellate fatty acids to the jellyfish. Jellyfish in the 10% PAR treatment shrank during the experiment and their fatty acid profiles did not reflect any shift towards increased heterotrophy. On days 22 and 69 concentrations of chl a, zooxanthellae and [chl a] zooxanthella^− 1 were determined. [chl a] and [chl a] zooxanthella^− 1, initially increased in the lower light treatments but decreased by the end of the experiment indicating that jellyfish may adapt to reduced light intensity in the short-term but that long-term exposure to reduced light results in compromised performance.     

Acclimation effect on fatty acids of the coral Montipora digitata and its symbiotic algae

Lipids play a key role in thermal and photo-acclimation processes, yet they are often neglected in stress studies. We investigated the influence of different light intensities and an increase of temperature on the fatty acid composition of the coral Montipora digitata and its symbiotic algae (i.e., zooxanthellae). Coral branches were subjected to 3 different light intensities (7, 30 and 95% sea surface photosynthetic active radiation) in filtered seawater for 35 days. Fatty acids as methyl esters were determined using gas chromatography (GC) and verified by GC-mass spectrometry. Different light intensities, but only in combination with increased temperature, significantly affected the fatty acid composition of the coral host and zooxanthellae. Temperature and light intensity increases caused reductions in the proportion of polyunsaturated fatty acids in both the host and symbionts. Most changes occurred in the host coral, which suggests that the host is more susceptible to environmental change than the symbiont, or that the host shields the symbionts from environmental change.     

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.     

Rapid effects of the intravenous injection of a medium-chain triglyceride: fish oil emulsion on the triglyceride fatty acid pattern of soleus muscle from omega3 fatty acid-depleted rats.

Second generation rats depleted in long-chain polyunsaturated omega3 fatty acids display several features of the metabolic syndrome, including visceral obesity, liver steatosis, insulin resistance, hypertension, and cardiac hypertrophy. In the framework of an extensive study on such metabolic, hormonal and functional perturbations, the phospholipid fatty acid pattern and ex vivo metabolism of D-glucose were recently investigated in the soleus muscle of these omega3-depleted rats. The present study deals with the triglyceride fatty acid content and pattern of the soleus muscle in control animals and omega3-depleted rats. Some of the latter rats were injected intravenously 60-120 minutes before sacrifice with either an omega3 fatty acid-rich medium-chain triglyceride/fish oil emulsion (omega3-FO rats) or a control medium-chain triglyceride/olive oil emulsion (omega3-OO rats). The total fatty acid content of triglycerides was comparable in control and omega3-depleted rats and, in both cases, inversely related to their C20:4omega6 relative content. At variance with the situation found in control rats, no long-chain polyunsaturated omega3 fatty acid (C18:3omega3, C20:5omega3, C22:5omega3, C22:6omega3) was detected in the omega3-depleted rats. Unexpectedly, the triglyceride content in most long-chain polyunsaturated omega6 fatty acids (C18:2omega6, C20:3omega6, C20:4omega6 and C22:4omega6) had also decreased in the latter rats. Moreover, the activity of Delta9-desaturase was apparently increased in the omega3-depleted rats, as judged from the C16:1omega7/C16:0 and C18:1omega9/C18:0 ratios. The omega3-FO rats differed from omega3-OO rats by a lower contribution of C18:2omega6 metabolites (C18:3omega6, C20:3omega6, C20:4omega6 and C22:4omega6). These findings indicate that the prior injection of the medium-chain triglyceride/fish oil emulsion, known to increase the muscle phospholipid content in long-chain polyunsaturated omega3 fatty acids, may nevertheless accentuate the depletion in long-chain polyunsaturated omega6 fatty acids otherwise found in the triglycerides of omega3-depleted rats. Such a dual effect is reminiscent of that observed, under the same experimental conditions, for selected variables in D-glucose metabolism in the soleus muscle.     

Biosynthesis of polyunsaturated fatty acids in zooxanthellae and polyps of corals

The fatty acid (FA) composition of zooxanthellae, polyp tissue, and intact colonies was determined in soft coral Sinularia sp. and hard coral Acropora sp. Analysis of the distribution of polyunsaturated fatty acids (PUFAs) among the zooxanthellae and the host organism showed that 18: 3n-6 and C_18–22 PUFAs of the n-3 series (18: 4n-3, 20: 5n-3, 22: 5n-3, and 22: 6n-3) were mainly synthesized by the zooxanthellae and that C_20–22 PUFAs of the n-6 series (20: 3n-6, 20: 4n-6, and 22: 4n-6) were synthesized in the polyp tissue. Soft coral polyps were able to synthesize tetracosapolyenoic FAs (24: 5n-6 and 24: 6n-3) and 18: 2n-7, their zooxanthellae synthesized C₁₆ PUFAs (16: 2n-7, 16: 3n-4, and 16: 4n-1). It is supposed that the biosynthesis of 16: 2n-7 in Sinularia sp. and 18: 3n-6 in Acropora sp. is catalyzed by Δ6 desaturase. The relatively even distribution of three FAs (18: 2n-6, 18: 3n-6, and 16: 2n-7) among lipids of zooxanthellae and coral polyps indicates the possible transport of these FAs between symbionts and the host organism.     

Positional Distribution of Acyl and Alk-1-enyl Groups in Grey and White Matter Ethanolamine and Choline Phosphoglycerides of a Marsupial, the Koala (Phascolarctos cinereus)

The major phosphoglycerides in grey and white matter from the brain of the koala have been separated and examined. The major polyunsaturated fatty acids present in both the diacyl- and alk-1-enyl acylglycerophosphorylethanolamines from grey matter were 22:6 omega 3, 20:4 omega 6, and 22:4 omega 6. In both grey and white matter, 22:6 omega 3 and 20:4 omega 6 were concentrated in the 2-position of diacylglycerophosphorylethanolamines and 22:4 omega 6 in the 2-position of alk-1-enylacylglycerophosphorylethanolamines; polyunsaturated fatty acid levels were higher in diacylglycerophosphorylethanolamines. Ethanolamine phosphoglyceride fractions from grey matter were enriched in polyunsaturated fatty acids compared with those from white matter. The acyl groups 18:0, 18:1, and 16:0 and their alk-1-enyl analogues were prominent in grey and white matter ethanolamine phosphoglycerides; 18:1 was dominant in white matter alk-1-enylacylglycerophosphorylethanolamines. The plasmalogen composition of ethanolamine phosphoglycerides was 55% in grey matter and 76% in white matter. Choline phosphoglycerides contained negligible plasmalogen and low polyunsaturated fatty acid levels. Diacylglycerophosphorylcholine was characterized by high levels of 16:0 and 18:1. Similar acyl group distributions were estimated in the 1-position in both grey and white matter, 16:0 being present at greater than 50%. The presence of the molecular species 18:0/22:6 omega 3 was indicated in grey matter diacylglycerophosphorylethanolamine, 18:1/18:1 in white matter alk-1-enylcylglycerophosphorylethanolamine, and 16:0/18:1 in white matter diacylglycerophosphorylcholine.     

Brugia malayi: microfilarial polyunsaturated fatty acid composition and synthesis

The polyunsaturated fatty acid composition of Brugia malayi microfilariae was analyzed by gas chromatography and compared to that of sera from B. malayi-infected jirds. The essential fatty acid, linoleic acid (18:2 omega 6), was the most abundant fatty acid present in both microfilarial total lipids and phospholipids as well as in jird sera. In contrast, arachidonic acid (20:4 omega 6), as well as the 18:3 omega 6, 20:2 omega 6, and 20:3 omega 6 intermediates that are formed in the enzymatic conversion of linoleic acid to arachidonic acid, were proportionally more abundant in microfilariae than in jird sera. To assess the capacity of microfilariae to transform linoleic acid into arachidonic acid, B. malayi microfilariae were incubated with [14C]linoleic acid. Microfilarial lipids were extracted and resolved by high-pressure liquid chromatography and thin-layer chromatography. A portion of [14C]linoleic acid incorporated by microfilariae was converted to [14C]arachidonic acid. Thus, microfilariae can not only incorporate exogenous arachidonic acid, as previously demonstrated, but can also synthesize arachidonic acid from exogenous linoleic acid. The capacity of microfilariae to utilize specific host polyunsaturated fatty acids raises the possibility that intravascular filarial parasites may synthesize eicosanoid metabolites of arachidonic acid that could mediate filarial-host cell interactions.     

Acetate-1-14C incorporation into polyunsaturated fatty acids of phospholipids of developing chick brain

The incorporation of acetate-1-(14)C into the polyunsaturated fatty acids of glycerophosphatides of chick embryonic brain has been studied. After the injection of acetate-1-(14)C into the yolk sac, differences were found in the degree of labeling of the major fatty acids of the omega3 and omega6 series. Arachidonic acid (20:4omega6) showed a high degree of radioactivity while docosahexaenoic acid (22:6omega3) was poorly labeled, at a period of brain development when both fatty acids were being actively deposited. Evidence is presented to indicate that the low activity in docosahexaenoic acid is not explicable on the basis of either a low or high rate of turnover of this polyenoic acid. Similar results were obtained whether the rapid early or slower late stage of brain development was examined. It is suggested that the elongation of omega3 and omega6 series acids may be under the control of different regulatory mechanisms.     

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.     

Manipulation of Plasma Membrane Fatty Acid Composition of Fetal Rat Brain Cells Grown in a Serum-Free Denned Medium

Modifications of plasma membrane acyl-linked phospholipid fatty acid composition were produced by supplementing the culture medium with essential fatty acids. The plasma membrane fraction was purified by Percoll gradient centrifugation from dissociated fetal rat brain cells grown in a serum-free culture medium. Both the concentration dependence and the time course of the modifications were examined. Supplementation of the medium with essential polyunsaturated fatty acid, linolenic acid (18:3 omega 3) or linoleic acid (18:2 omega 6), produced incorporation of the elongated and desaturated products of omega 3 or omega 6 class, respectively, i.e., the incorporation was class specific. Within each class, the most unsaturated and elongated members, i.e., terminal members, were preferentially incorporated until they reached a maximum concentration within 6-7 days. At higher concentrations of supplemented fatty acids, additional class specific incorporation in plasma membrane was produced by an increase in the concentration of intermediate members. At the same time, the concentration of monounsaturated fatty acids declined and that of saturated fatty acids remained unchanged. The modifications in fatty acid composition were reversible, with the time course similar to that of incorporation. The total plasma membrane phospholipid and sterol contents did not change with alterations of fatty acid composition, but did change with time in culture. This preparation should prove useful for investigating the role of polyunsaturated fatty acids in brain cell functions, including neuronal excitability.     

Effect of supplementation of arachidonic acid (AA) or a combination of AA plus docosahexaenoic acid on breastmilk fatty acid composition

We investigated whether supplementation with arachidonic acid (20:4 omega 6; AA), or a combination of AA and docosahexaenoic acid (22:6 omega 3; DHA) would affect human milk polyunsaturated fatty acid (PUFA) composition. Ten women were daily supplemented with 300 mg AA, eight with 300 mg AA, 110 mg eicosapentaenoic acid (20:5 omega 3; EPA) and 400 mg DHA, for one week and eight women served as unsupplemented controls. Milk samples were collected on days 0, 1 and 7. The fatty acid composition of the milk was analyzed by capillary gas chromatography with flame ionisation detection. Supplementation with AA alone had no effect on breastmilk AA, but tended to reduce EPA and DHA levels. Administration of a combination of AA, EPA and DHA tended to increase both milk AA and long chain PUFA (LCPUFA)omega 3 content. A larger simultaneous increase of milk AA, DHA and EPA than observed in the present study can probably be accomplished by the use of a combination of a lower LCPUFA omega 6/LCPUFA omega 3 ratio and higher AA, EPA and DHA dosages.     

Dietary polyunsaturated fatty acids (C18:2 omega6 and C18:3 omega3) do not suppress hepatic lipogenesis

Omega 3 polyunsaturated fatty acids are promoted as beneficial in the prevention of metabolic and cardiovascular diseases. In general, dietary omega 3 fatty acids are derived from plant sources as linolenic acid (LNA, C18:3 omega3) the precursor to eicosapentaenoic acid (EPA, C20:5 omega3) and docosahexaenoic acid (DHA, C22:6 omega3). However, it remains unclear if the polyunsaturated fatty acid (PUFA) LNA can provide the same health benefits as the very long chain highly unsaturated fatty acids (HUFA) EPA and DHA generally derived from oily fish. In this study, mice were fed synthetic diets containing lard (low in PUFA and HUFA), canola oil (to supply PUFA), or a mixture of menhaden and arasco (fish and fungal) oils (to supply HUFA) for 8 weeks. The diets were neither high in calories nor fat, which was supplied at 6%. The lard and canola oil diets resulted in high levels of hepatic triglycerides and cholesterol and elevation of lipogenic gene expression. By comparison livers from mice fed the fish/fungal oil diet had low levels of lipid accumulation and more closely resembled livers from mice fed standard laboratory chow. SREBP1c and PPARgamma gene and protein expression were high in livers of animals fed diets containing lard or canola oil compared with fish/fungal oil. Hepatic fatty acid analyses indicated that dietary PUFA were efficiently converted to HUFA regardless of source. Therefore, differences in hepatic lipid levels and gene expression between dietary groups were due to exogenous fatty acid supplied rather than endogenous pools. These results have important implications for understanding the regulation of hepatic lipogenesis by dietary fatty acids.     

Reduced placental docosahexaenoic acid levels associated with increased levels of sFlt-1 in preeclampsia

Our earlier studies, in preeclamptic women have shown altered levels of long chain polyunsaturated fatty acids (LCPUFA), essential constituents of the cell membrane lipids responsible for membrane stability as one of the key factors contributing to the pathophysiology of preeclampsia. We have also reported elevated levels of sFlt-1 in preeclampsia. The present study examines the levels of LCPUFA and their association with sFlt-1 levels in 69 pre-eclamptic women and 40 normotensive women. DHA and omega 3 fatty acid levels were lower (p<0.001) while arachidonic acid and omega 6 fatty acid levels were higher (p<0.05) in preeclamptic women as compared to normotensive women. Maternal plasma sFlt-1 levels were higher (p<0.05) in preeclamptic women and were negatively associated with DHA (p=0.008) and omega 3 fatty acids concentrations (p=0.031). Our results suggest that altered placental LCPUFA may result in altered membrane lipid fatty acid composition leading to increased release of sFlt-1 in circulation.     

Lipids and fatty acids in muscle, liver and skin of three edible fish from the Senegalese coast: Sardinella maderensis, Sardinella aurita and Cephalopholis taeniops

Lipid content and fatty acid composition were determined in three species of edible fish caught in Senegalese waters during the upwelling season (January, 1993). Sardinella maderensis and Sardinella aurita are fat fish containing more than 5% (fresh wt.) of lipids, whereas Cephalopholis taeniops is a lean fish with approximately 1% of lipids. Skin, liver and muscle were studied for each fish species. About 40 fatty acids were identified by GC and GC/MS as methyl esters and N-acyl pyrrolidides. Palmitic acid was the main acid in the muscle and skin of all samples studied (20-33% of total fatty acids). Oleic acid was the main fatty acid in the liver of S. maderensis (27.2%+/-0.1) and S. aurita (44.7%+/-0.1). Arachidonic acid was a minor component in all samples. The flesh (muscle) of the three fish species contained high concentrations of omega3 polyunsaturated fatty acids (PUFA), ranging from 16.0 to 29.1% and including 20:5 omega3 (eicosapentaenoic acid, EPA) and 22:6 omega3 (docosahexaenoic acid, DHA) acids as major components. These two acids together accounted for 24.7%+/-0.1 and 12.9%+/-0.1 of total acids in the skin of S. maderensis and S. aurita, respectively. The percentages of PUFA found in the fish studied were very similar to those in fish used commercially as sources of PUFA. Muscle sterols, which accounted for 9-11% of total lipids, consisted mainly of cholesterol (up to 97% of total sterols).     

The role of the collagen tripeptide fragment GER in the adhesion activation and modification of fatty acid composition in membrane phospholipids of CHO-K1 cells

It has been found that multiply repeated tripeptide fragment GER (Gly-Glu-Arg) from different collagen types stimulates nonspecific adhesion of CHO-K1 cells. Activation of cell adhesion is accompanied by modifications in fatty acid composition of cell membrane phospholipids. Cell incubation with the synthetic peptide increases the unsaturation indexes of phosphatidylcholin (PC), phosphatidylethanolamine (PEA) and phosphatidylinositol (PI). Arachidonic (C20:4omega6) acid is mainly contributed to the increased unsaturation index of PI. In the case of PC and PEA not only arachidonic acid but also other unsaturated fatty acids: docosatetraenoic (C22:4omega6), docosapentaenoic (C22:5omega3) and docosahexaenoic (C22:6omega3) acids are implicated in the index increasing. Besides, the elevation of relative content of molecules with polyenoic fatty acids in the group of PI molecules is accompanied by decrease in monoenoic fatty acids caused mainly by decrease in the oleic (C18:1) acid level. The role of the investigated peptide: 1) in the activation of cell adhesion as a regulator of active or non active state of integrin receptors: 2) in the alterations of fatty acid composition in main classes of phospholipids as modulator of fluidity level in annular lipid zones around these adhesive molecules is discussed.     

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.     

Regulation of fatty acid biosynthesis as a possible mechanism for the mitoinhibitory effect of fumonisin B1 in primary rat hepatocytes

The mitoinhibitory effect of fumonisin B1 (FB1) on the mitogenic response of epidermal growth factor (EGF) was investigated in primary hepatocyte cultures with respect to the alterations in the omega6 fatty acid metabolic pathway. Fatty acid analyses of hepatocytes showed that EGF treatment resulted in a significant decrease in the relative levels of 20:4omega6 (arachidonic acid) and an increase in 18:2omega6 (linoleic acid). Supplementation of the hepatocyte cultures with 20:4omega6 in the absence of EGF resulted in an increase in the total omega6 and omega6/omega3 fatty acid ratio. Addition of 20:5omega3 (eicosapentaenoic acid) resulted in an increase of the relative levels of the long chain omega3 fatty acids at the expense of the omega6 fatty acids. When 20:4omega6 and 20:5omega3 was added in the presence of EGF, the mitogenic response of EGF was increased and decreased respectively. When compared to the fatty acid profiles in the absence of EGF, the decreased mitogenic response coincided with a decrease of total omega6 fatty acids and total polyunsaturated fatty acids (PUFA). In addition, the saturated and mono-unsaturated fatty acids increased and the polyunsaturated/saturated (P/S) fatty acid ratio decreased which implied a more rigid membrane structure. Addition of prostaglandin E2 (PGE2) and prostaglandin E1 (PGE1) stimulated and inhibited the mitogenic response respectively. Ibuprofen, a known cyclooxygenase inhibitor, and FB1 inhibited the EGF-induced mitogenic response in a dose-dependent manner. The mitoinhibitory effect of FB1 on the EGF response was counteracted by the addition of PGE2. FB1 also disrupts the omega6 fatty acid metabolic pathway in primary hepatocytes, resulting in the accumulation of C18:2omega6 in phospatidylcholine and triacylglicerol. The disruption of the omega6 fatty acid metabolic pathway and/or prostaglandin synthesis is likely to be an important event in the mitoinhibitory effect of FB1 on growth factor responses.     

Changes in myocardial lipid composition during surgery with cold and chemical cardioplegia

The changes of children myocardium lipid composition were studied for the first time during surgical intervention under cold crystalloid cardioplegia. The surgical intervention was performed as a result of congenital heart disease--atrial septal defect. It was shown that the quantity of short chain fatty acids decreased and the amount of long chain fatty acids increased in the content of phospholipid fraction. Simultaneously the amount of linoleic (C18:2 omega 6), of docosahexaenoic (C22:6 omega 3) and of some other fatty acids decreased in the content of cholesterol esthers. The accumulation of free linoleic (C18:2 omega:6), (C18:2 omega:4) and linolenic (C18:3 omega:6) acids was found. Reperfusion caused the additional changes of myocardium lipid composition. The amount of palmitic (C16:0) acid decreased by 30%. The quantity of some other saturated free fatty acids also diminished. Simultaneously the content of free oleic (C18:1 omega 9) also decreased as a consequence of lipid peroxidative processes activation. The ratio of omega 6/omega 3 increased during the few first minutes of reperfusion in the fraction of free fatty acids and cholesterol esthers.     

Fatty acids bound to alpha-fetoprotein and albumin during rat development

The time-course levels and composition of the fatty acids bound to rat alpha-fetoprotein (AFP) and albumin from several sources, were determined throughout development, and related to the intake of lipids from milk and the compositional changes in brain and liver fatty acids. The major fatty acids bound to AFP were acids bound to AFP were polyunsaturated and mainly docosahexaenoic acid (22:6(n-3], either from fetal serum (23.1%) or whole fetuses (21.6%), whereas palmitic (34.1%) and oleic (29.9%) acids were the main acids bound to albumin from the same sources. Amniotic fluid AFP contained less fatty acids (0.8 mol/mol protein) than that of fetal serum (1.4 mol/mol protein), and especially noticeable was a reduced amount of 22:6 (9.6%). Both AFP-concanavalin A microforms showed identical fatty acid composition. Levels of 22:6 bound to AFP decreased quickly after birth until a minimum at 8-10 days, increasing moderately thereafter. This minimum is coincident in time with a maximal accumulation of this fatty acid by brain and a loss of 22:6 by liver. Except for colostrum, levels of 22:6 in milk lipids were low and fairly constant, but always greater than those of its precursor, linolenic acid (18:3 (n-3]. These results support a specialized role of AFP in the plasma transport and tissue delivery of polyunsaturated fatty acids, and mainly docosahexaenoic acid.