Acids In Phosphatidylethanolamine Research Articles

Phospholipid Profiles Are Selectively Altered in the Putamen and White Frontal Cortex of Huntington's Disease.

Huntington’s disease (HD) is a genetic, neurodegenerative illness that onsets in late adulthood as a series of progressive and terminal cognitive, motor, and psychiatric deficits. The disease is caused by a polyQ mutation in the Huntingtin gene (HTT), producing a polyglutamine expansion in the Huntingtin protein (HTT). HTT interacts with phospholipids in vitro; however, its interactions are changed when the protein is mutated in HD. Emerging evidence suggests that the susceptibility of brain regions to pathological stimuli is influenced by lipid composition. This study aimed to identify where and how phospholipids are changed in human HD brain tissue. Phospholipids were extracted using a modified MTBE method from the post-mortem brain of 13 advanced-stage HD patients and 13 age- and sex-matched controls. Targeted precursor ion scanning mass spectrometry was used to detect phospholipid species. In the white cortex of HD patients, there was a significantly lower abundance of phosphatidylcholine (PC) and phosphatidylserine (PS), but no difference in phosphatidylethanolamine (PE). In HD putamen, ester-linked 22:6 was lower in all phospholipid classes promoting a decrease in the relative abundance of ester polyunsaturated fatty acids in PE. No differences in phospholipid composition were identified in the caudate, grey cortex or cerebellum. Ether-linked PE fatty acids appear protected in the HD brain, as no changes were identified. The nature of phospholipid alterations in the HD brain is dependent on the lipid (subclass, species, and bond type) and the location.

Acute and chronic effects of temperature on membrane adjustments in the gills of a neotropical catfish.

Structural modifications in the gill membranes maintain homeostasis under the influence of temperature changes. We hypothesized that thermal acclimation would result in significant modification of phospholipid fatty acids, with modulation of sodium pump activity during acute (24 and 48h) and chronic (15days) thermal shifts in the neotropical reophilic catfish Steindachneridion parahybae. Indeed, the time-course experiment showed acute and chronic changes in gill membrane at the lowest temperatures, notably linked to maintenance of membrane fluidity: significant preferential changes in phosphatidylethanolamine, with decrease of saturated fatty acids and increase of C18:1 in all groups kept below 30°C in chronic trial, increase in polyunsaturated fatty acids n6 and C18:1 at 17 and 12°C compared to 24°C, as soon as the temperature was changed (initial time). Additionally, the activity of the sodium pump increased at 12°C, but without apparent connection with the altered lipid environment. The animals maintained at the lowest temperature showed a higher mortality, possibly because of the approach to the minimum critical temperature for this species, and unexpected results of changes in the fatty acid profile, such as decreased docosahexaenoic acid in phosphatidylethanolamine and increased saturated fatty acids in phosphatidylcholine. This set of mechanisms highlights rheostatic adjustments in this species in the face of temperature changes.

The Changes in Composition of Phospholipid Subclasses Fatty Acids Prepared from Prediapausing and Postdiapausing Adults of Sunn Pest, Eurygaster integriceps Put. (Heteroptera: Scutelleridae)

Bu çalışmada, süne, Eurygaster integriceps’in diyapoz öncesi ergin ve diyapoz sonrası erginlerinin fosfatidilkolin (PC), fosfatidiletanolamin (PE), fosfatidilinositol (PI) ve fosfatidilserin (PS) gibi fosfolipit (PL) altsınıflarının yağ asidi kompozisyonundaki değişiklikler araştırılmıştır. Fosfolipit alt sınıflarının ayrılmasında İnce Tabaka Kromatoğrafisi tekniği, yağ asitlerinin analizinde ise Gaz kromatoğrafi cihazı kullanılmıştır. Eurygaster integriceps’in PL altsınıflarında gözlenen dominant yağ asitleri, doymuş yağ asitlerinden (SFA) palmitik asit (16:0), tekli doymamış yağ asitlerinden (MUFA) oleik asit (18:1n-9) ve çoklu doymamış yağ asitlerinden (PUFA) linoleik asit (18:2n-6) idi. Diyapoz öncesi ve diyapoz sonrası erginlerin PC, PE ve PS fraksiyonlarının yağ asidi içeriğindeki değişikliklerin benzer olduğu bulunmuştur. Diyapoz sonrası erginlerin bu fraksiyonlarında 16:0, 18:0 ve ∑SFA yüzdeleri diyapoz öncesi erginlere oranla daha düşük; ancak16:1n-7, ∑MUFA, 18:2n-6 ve ∑PUFA ise daha yüksek olarak bulunmuştur. Sünenin diyapoz sonrası bireylerin PE ve PC fraksiyonlarındaki 18:1n-9 düzeyi, diyapoz öncesi bireylerden önemli derecede daha yüksek olarak tespit edilmiştir. Diyapoz sonrası erginlerin tüm PL altsınıflarındaki doymamış yağ asitlerinin doymuş yağ asitlere oranı (UFA/SFA), diyapoz öncesi erginlerden daha yüksek bulunmuştur.

Covalent Modification of Phosphatidylethanolamine by Benzyl Isothiocyanate and the Resultant Generation of Ethanolamine Adduct as Its Metabolite.

Benzyl isothiocyanate (BITC), a dietary isothiocyanate (ITC) derived from cruciferous vegetables, has anticancer properties. It is believed that the ITC moiety (-N═C═S) that reacts predominantly with thiol compounds plays a central role in triggering the activities resulting from these properties. Recent studies have demonstrated that ITCs also covalently modify amino moieties in a protein. In this study, we examined the chemical reaction between BITC and the aminophospholipid, phosphatidylethanolamine (PE), in the cell membrane or lipoprotein particle. To detect the BITC-modified PE, the bond between ethanolamine (EA) and phosphatidic acid in PE was cleaved using phospholipase D to form the BITC-EA adduct, which was then measured. BITC-EA was detected from the BITC-treated unilamellar liposome and low-density lipoprotein even with only a few micromoles of BITC treatment, suggesting that BITC might react with not only a thiol/amino group of a protein but also an amino moiety of an aminophospholipid. Moreover, after incorporating BITC-PE included in the liposomes into the cultured cells or after direct exposure of BITC to the cells, free BITC-EA was excreted and accumulated in the medium in a time-dependent manner. It indicates that an intracellular enzyme catalyzes the cleavage of BITC-PE to produce BITC-EA. Because the ITC-amine adduct is stable, the ITC-EA adduct could be a promising indicator of ITC exposure in vivo.

Induction of an altered lipid phenotype by two cancer promoting treatments in rat liver

Changes in lipid metabolism have been associated with tumor promotion in rat liver. Similarities and differences of lipid parameters were investigated using the mycotoxin fumonisin B1 (FB1) and the 2-acetylaminofluorene/partial hepatectomy (AAF/PH) treatments as cancer promoters in rat liver. A typical lipid phenotype was observed, including increased membranal phosphatidylethanolamine (PE) and cholesterol content, increased levels of C16:0 and monounsaturated fatty acids in PE and phosphatidylcholine (PC), as well as a decrease in C18:0 and long-chained polyunsaturated fatty acids in the PC fraction. The observed lipid changes, which likely resulted in changes in membrane structure and fluidity, may represent a growth stimulus exerted by the cancer promoters that could provide initiated cells with a selective growth advantage. This study provided insight into complex lipid profiles induced by two different cancer promoting treatments and their potential role in the development of hepatocyte nodules, which can be used to identify targets for the development of chemopreventive strategies against cancer promotion in the liver.

Determination of fatty acids of phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol and phosphatidylserine from the cephalopedal and total body of edible snail Helix lucorum

Objective: The objective of the study was to examine the nutritive value of Helix lucorum meat and to create awareness about fatty acid composition of phospholipid subclasses of the total body and cephalopedal tissues of the snail. Methods: Thin layer chromatography plates contained lipid samples placed in the chromatography tank containing: chloroform/ethanol/water/triethylamine. The phospholipid subclasses were dissolved in about 5 ml of methanol and 5 drop of sulfuric acid. The mixture was refluxed for 2 h to form fatty acid methyl esters at 85 °C. Fatty acids were detected by Gas chromatography. Results: The most noteworthy result was the high level of C20:2ω6 in PE (10.49%-11.35%) and PC (17.33%-12.96%). Appreciable quantity of essential fatty acid C18:2ω6 was determined in PC (20.85%-17.46%) and PE (16.88%-17.53%) from both tissues. Precursor of eicosanoids, C20:4ω6 was found apparently high in PI, PS and PE of the total body. The highest level of ΣPUFA was 63.90% in PE from total body whereas the highest level of ΣSFA was 60.79% in PI from the cephalopedal. ΣMUFA level was pretty low in PI, PS and PE. Conclusion: The study is a guide for biochemical and nutritional value of edible snails and can be useful for further investigation on physiological and systematic studies of other species.

Expression and characterization of Rv0447c product, potentially the methyltransferase involved in tuberculostearic acid biosynthesis in Mycobacterium tuberculosis

In this study, a previously uncharacterized gene (Rv0447c) of Mycobacterium tuberculosis, designated as an unknown fatty-acid methyltransferase (ufaA1), was cloned, expressed in Escherichia coli, and purified. The biochemical characterization of the purified protein (UfaA1) showed it to be a methyltransferase that catalyzes biosynthesis of the tuberculostearic acid (10-methylstearic-acid, TSA), a significant constituent lipid of the mycobacterial cell wall and a clinical marker of the disease. Here, we show that UfaA1 transfers the methyl group from S-adenosyl-l-methionine (SAM) to the double bond of oleic acid in phosphatidylethanolamine or phosphatidylcholine to produce TSA. Optimal activity was obtained between pH 7.0 and pH 8.0. The methyltransferase activity of UfaA1 was severely inhibited by S-adenosyl-l-homocysteine. The Km values for dioleyl phosphatidylethanolamine, SAM, and nicotinamide adenine dinucleotide phosphate were 14, 13, and 83 µM, respectively, with Vmax of 1.3-1.6 nmol/Min. These results identify the Rv0447c gene product of M. tuberculosis as the methyltransferase that catalyzes the biosynthesis of TSA. This provides new information in mycobacterial cell wall synthesis.

15-Lipoxygenase eicosanoids are the putative ligands for vanilloid receptors and peroxisome proliferator-activated receptors (PPARs)

We read the article by Zhao et al. (1), which showed that epithelial 15-lipoxygenase 1 (15LO1) and its product 15-hydroxyeicosatetraenoic acid phosphatidylethanolamine interact with phosphatidylethanolamine-binding protein (PEBP1) to enhance MAPK signaling (ERK activation) in human airway epithelia. This can then be seen as an internal mechanism in airway epithelium for adjusting the gain settings of critical inflammatory pathways integral to asthma pathogenesis. However, this model rests critically on three assumptions: (i) Epithelial 15LO1 is the major form of 15LO1 and the source of 15S-hydroxyeicosatetraenoic acid (15S-HETE), (ii) metabolites or eicosanoids of 15LO1 such as 15S-HETE are not released extracellularly, and (iii) these eicosanoids do not influence MAPK signaling through any other receptor. The authors explicitly stated that “15HETE is not released extracellularly” and that “unlike other eicosanoids, 15LO1 does not appear to function through receptor-mediated mechanisms, and, indeed, no receptor has been identified.” In this model, all these signaling events (15LO1–15-hydroxyeicosatetraenoic acid-phosphatidylethanolamine-ERK) are direct and exclusively occur inside the airway epithelia. This is potentially misleading. First, a minor discrepancy in the data, whereby 15LO1 was nearly undetectable in fresh bronchial epithelia isolated from normal and air–liquid interface (ALI)-cultured human bronchial epithelial cells without IL-13 induction [figures 1a and 2b (1)] but strongly expressed even without IL-13 stimulation in other supposed ALI epithelial cultures [figure 6a (1)], could be secondary to possible contamination of ALI cultures with macrophages. It has been reported that macrophages are also important sources of 15LO1 and 15(S)-HETE in the airway, with uptake and incorporation of 15(S)-HETE by epithelial cells (2). As their Materials and Methods (1) did not report the use of any technique to confirm the purity of isolated airway epithelia or cultured epithelia and to exclude macrophage contamination, we wonder if this possibility has been excluded. Second, eicosanoids of 15LO1, including 15S-HETE, have been found in biological fluids such as BAL fluid supernatants and sputum supernatants (2), indicating they also could be secretory with an extracellular role. Third, eicosanoids of 15LO directly bind with vanilloid receptors and PPARs (3, 4), indicating that 15S-HETE also could lead to receptor-mediated signaling for MAPK activation. TRPV1, one of the vanilloid receptors that may be important in refractory asthma, was found to be expressed in bronchial epithelia rather than macrophages, which indicates a possible crosstalk between macrophage and epithelium through secreted 15S-HETE from macrophages. Indeed, 15S-HETE has been considered as a 15LO2 metabolite rather than a 15LO1 metabolite (13S-HODE) (4), which is contradictory to the title of the article by Zhao et al. (1). Exogenous induction with metabolites of 15LO1 and 15LO2 differentially regulate MAPK signaling involving PPAR (4).

Turnover of nonessential fatty acids in cardiolipin from the rat heart

Cardiolipin (CL) is a unique phospholipid (PL) found in the mitochondria of mammalian cells. CL remodeling is accompanied by turnover of its fatty acid acyl groups. Abnormalities in CL remodeling have been found in Barth's syndrome, diabetes, and obesity. The objective of this study was to determine nonessential fatty acid turnover in CL and phosphatidylethanolamine (PE) in the rat heart in vivo. Sprague-Dawley rats were fed either a regular chow or a high-fat diet for 15 weeks, and consumed 6% deuterium-enriched drinking water as a tracer for 14 days. CL and PE were extracted from cardiac tissue and isolated by TLC. Fatty acids from CL, PE, and plasma were analyzed by GC/MS for deuterium incorporation. Results showed oleate and vaccenate turnover were the highest in CL whereas palmitate and stearate turnover were low. Among the nonessential fatty acids in PE, turnover of stearate and vaccenate were the highest. The high turnover rate in vaccenate was unexpected, because vaccenate previously had no known metabolic or physiologic function. In conclusion, the similarly high turnover rates of both oleate and vaccenate readily suggest that remodeling is an important functional aspect of PL metabolism in CL.

Inverse Association between trans Isomeric and Long-Chain Polyunsaturated Fatty Acids in Pregnant Women and Their Newborns: Data from Three European Countries

Background:trans unsaturated fatty acids are thought to interfere with essential fatty acid metabolism. To extend our knowledge of this phenomenon, we investigated the relationship between trans isomeric and long-chain polyunsaturated fatty acids (LCPUFA) in mothers during pregnancy and in their infants at birth. Methods: Fatty acid composition of erythrocyte phosphatidylcholine (PC) and phosphatidylethanolamine (PE) was determined in Spanish (n = 120), German (n = 78) and Hungarian (n = 43) women at the 20th and 30th week of gestation, at delivery and in their newborns. Results: At the 20th week of gestation, the sum of trans fatty acids in PE was significantly (p < 0.01) lower in Hungarian [0.73 (0.51), % wt/wt, median (IQR)] than in Spanish [1.42 (1.36)] and German [1.30 (1.21)] women. Docosahexaenoic acid (DHA) values in PE were significantly (p < 0.01) higher in Hungarian [5.65 (2.09)] than in Spanish [4.37 (2.60)] or German [4.39 (3.3.2)] women. The sum of trans fatty acids significantly inversely correlated to DHA in PCs in Spanish (r = –0.37, p < 0.001), German (n = –0.77, p < 0.001) and Hungarian (r = –0.35, p < 0.05) women, and in PEs in Spanish (r = –0.67, p < 0.001) and German (r = –0.71, p < 0.001), but not in Hungarian (r = –0.02) women. Significant inverse correlations were seen between trans fatty acids and DHA in PEs at the 30th week of gestation (n = 241, r = –0.52, p < 0.001), at delivery (n = 241, r = –0.40, p < 0.001) and in cord lipids (n = 218, r = –0.28, p < 0.001). Conclusion: Because humans cannot synthesize trans isomeric fatty acids, the data obtained in the present study support the concept that high maternal trans isomeric fatty acid intake may interfere with the availability of LCPUFA both for the mother and the fetus.

Phosphoinositide Binding Differentially Regulates NHE1 Na+/H+ Exchanger-dependent Proximal Tubule Cell Survival

Tubular atrophy predicts chronic kidney disease progression, and is caused by proximal tubular epithelial cellcaused by proximal tubular epithelial cell (PTC) apoptosis. The normally quiescent Na(+)/H(+) exchanger-1 (NHE1) defends against PTC apoptosis, and is regulated by PI(4,5)P(2) binding. Because of the vast array of plasma membrane lipids, we hypothesized that NHE1-mediated cell survival is dynamically regulated by multiple anionic inner leaflet phospholipids. In membrane overlay and surface plasmon resonance assays, the NHE1 C terminus bound phospholipids with low affinity and according to valence (PIP(3) > PIP(2) > PIP = PA > PS). NHE1-phosphoinositide binding was enhanced by acidic pH, and abolished by NHE1 Arg/Lys to Ala mutations within two juxtamembrane domains, consistent with electrostatic interactions. PI(4,5)P(2)-incorporated vesicles were distributed to apical and lateral PTC domains, increased NHE1-regulated Na(+)/H(+) exchange, and blunted apoptosis, whereas NHE1 activity was decreased in cells enriched with PI(3,4,5)P(3), which localized to basolateral membranes. Divergent PI(4,5)P(2) and PI(3,4,5)P(3) effects on NHE1-dependent Na(+)/H(+) exchange and apoptosis were confirmed by selective phosphoinositide sequestration with pleckstrin homology domain-containing phospholipase Cδ and Akt peptides, PI 3-kinase, and Akt inhibition in wild-type and NHE1-null PTCs. The results reveal an on-off switch model, whereby NHE1 toggles between weak interactions with PI(4,5)P(2) and PI(3,4,5)P(3). In response to apoptotic stress, NHE1 is stimulated by PI(4,5)P(2), which leads to PI 3-kinase activation, and PI(4,5)P(2) phosphorylation. The resulting PI(3,4,5)P(3) dually stimulates sustained, downstream Akt survival signaling, and dampens NHE1 activity through competitive inhibition and depletion of PI(4,5)P(2).

Non-ideal mixing and fluid–fluid immiscibility in phosphatidic acid–phosphatidylethanolamine mixed bilayers

Differential scanning calorimetry (DSC) was used to study the miscibility of phosphatidic acids (PAs) with phosphatidylethanolamines (PEs) as a function of chain length (n=14, 16) and degree of ionization of PAs at pH 4, pH 7, and pH 12. Phase diagrams were constructed using temperature data for onset and end of the phase transition obtained from the direct simulation of the heat-capacity curves. The phase diagrams were analyzed by simulations of the coexistence curves utilizing a four-parameter regular solution model. For PA-PE mixtures, the non-ideality parameters are a function of composition indicating non-symmetric non-ideal mixing behavior. At pH 7, where the PA component is negatively charged, the systems DMPA:DMPE and DPPA:DPPE have positive non-ideality parameters ρ (1) in both phases, indicating a preferred aggregation of like molecules. In contrast, DMPA:DPPE and DPPA:DMPE mixtures had negative ρ (1) values. Measurements at pH 4 showed that mixed pair formation is favored when PA is protonated. At pH 12 where PA is doubly charged, highly positive ρ (l1) parameters are obtained for the liquid-crystalline phase except for the system DPPA:DPPE (ρ (1)<0). This indicates clustering of like molecules and possibly domain formation in the liquid-crystalline phase. DPPA:DMPE at pH 12 even shows a miscibility gap in the liquid-crystalline phase. Obviously, despite the presence of doubly charged PA a fluid-fluid immiscibility is induced.

A Critical Role for Ceramide Synthase 2 in Liver Homeostasis: I. ALTERATIONS IN LIPID METABOLIC PATHWAYS

Ceramide is an important lipid signaling molecule that plays critical roles in regulating cell behavior. Ceramide synthesis is surprisingly complex and is orchestrated by six mammalian ceramide synthases, each of which produces ceramides with restricted acyl chain lengths. We have generated a CerS2 null mouse and characterized the changes in the long chain base and sphingolipid composition of livers from these mice. Ceramide and downstream sphingolipids were devoid of very long (C22-C24) acyl chains, consistent with the substrate specificity of CerS2 toward acyl-CoAs. Unexpectedly, C16-ceramide levels were elevated, and as a result, total ceramide levels were unaltered; however, C16-ceramide synthesis in vitro was not increased. Levels of sphinganine were also significantly elevated, by up to 50-fold, reminiscent of the effect of the ceramide synthase inhibitor, fumonisin B1. With the exceptions of glucosylceramide synthase and neutral sphingomyelinase 2, none of the other enzymes tested in either the sphingolipid biosynthetic or degradative pathways were significantly changed. Total glycerophospholipid and cholesterol levels were unaltered, although there was a marked elevation in C18:1 and C18:2 fatty acids in phosphatidylethanolamine, concomitant with a reduction in C18:0 and C20:4 fatty acids. Finally, differences were observed in the biophysical properties of lipid extracts isolated from liver microsomes, with membranes from CerS2 null mice displaying higher membrane fluidity and showing morphological changes. Together, these results demonstrate novel modes of cross-talk and regulation between the various branches of lipid metabolic pathways upon inhibition of very long acyl chain ceramide synthesis.

Determination of intramuscular phospholipid classes and molecular species in Gaoyou duck

In this study, intramuscular phospholipid classes and molecular species in Gaoyou duck meat were determined. Classes of phospholipids were identified and quantified by normal phase HPLC combined with UV and evaporative light scattering detectors (ELSD). The main phospholipid classes (phosphatidylcholine and phosphatidylethanolamine) were prepared on a semi-preparative silica gel column by HPLC. Reverse phase HPLC was coupled in parallel with both an ELSD and a mass spectrometry in order to characterise molecular species of phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The results showed that Gaoyou duck meat had high quantities of PC and PE (64.66% and 28.10% of total phospholipids, respectively). Arachidonic acid was mainly present in PE and formed molecular species containing a saturated fatty acid, such as stearic or myristic acid; however, oleic acid together with palmitic or stearic acid formed the main molecular species in PC. The content of the molecular species with polyunsaturated fatty acids in PE accounted for 98.33%, while that in PC only 46.20%.

Improved paramagnetic chelate for molecular imaging with MRI

The relaxivity and transmetallation of two lipophilic paramagnetic chelates incorporated onto perfluorocarbon nanoparticles, i.e., gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid phosphatidylethanolamine (Gd-MeO-DOTA-PE) and gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid triglycine phosphatidylethanolamine (Gd-MeO-DOTA-triglycine-PE (Gd-MeO-DOTA-triglycine-PE)), were compared to a prototypic gadolinium-diethylene-triamine-pentaacetic acid bis-oleate (Gd-DTPA-BOA) paramagnetic formulation. Nanoparticles with MeO-DOTA-based chelates demonstrated higher relaxivity (40% higher for Gd-MeO-DOTA-PE and 55% higher for Gd-MeO-DOTA-triglycine-PE) and less transmetallation than the original Gd-DTPA-BOA-based agent.

Rat brain arachidonic acid metabolism is increased by a 6-day intracerebral ventricular infusion of bacterial lipopolysaccharide.

In a rat model of acute neuroinflammation, produced by a 6-day intracerebral ventricular infusion of bacterial lipopolysaccharide (LPS), we measured brain activities and protein levels of three phospholipases A2 (PLA2) and of cyclo-oxygenase-1 and -2, and quantified other aspects of brain phospholipid and fatty acid metabolism. The 6-day intracerebral ventricular infusion increased lectin-reactive microglia in the cerebral ventricles, pia mater, and the glial membrane of the cortex and resulted in morphological changes of glial fibrillary acidic protein (GFAP)-positive astrocytes in the cortical mantel and areas surrounding the cerebral ventricles. LPS infusion increased brain cytosolic and secretory PLA2 activities by 71% and 47%, respectively, as well as the brain concentrations of non-esterified linoleic and arachidonic acids, and of prostaglandins E2 and D2. LPS infusion also increased rates of incorporation and turnover of arachidonic acid in phosphatidylethanolamine, plasmenylethanolamine, phosphatidylcholine, and plasmenylcholine by 1.5- to 2.8-fold, without changing these rates in phosphatidylserine or phosphatidylinositol. These observations suggest that selective alterations in brain arachidonic acid metabolism involving cytosolic and secretory PLA2 contribute to early pathology in neuroinflammation.

Hypolipidemic Drugs Can Change the Composition of Rat Brain Lipids

Hypolipidemic drugs are potent serum cholesterol lowering agents used for prevention of coronary heart disease. In addition to their cholesterol lowering effect, these drugs exhibit both pleiotropic beneficial and various neurological side effects. Therefore, we analysed effect of the hypolipidemic drugs, fenofibrate and statins, on membrane lipid composition in the rat brain tissue. Male Wistar rats were given 0.1 mg of fenofibrate, lovastatin, pravastatin, fluvastatin or placebo (control) once daily for six weeks. In rats treated with lovastatin or pravastatin, decreased cholesterol and increased ceramide monohexoside contents in the brain tissue were observed in comparison with control. Treatment with fluvastatin or lovastatin resulted in increased sphingomyelin and decreased diphosphatidylglycerol contents. The most important changes in the fatty acid profile were observed in ceramide monohexosides; treatment with fluvastatin decreased the content of saturated and increased the content of polyunsaturated fatty acids. Fenofibrate treatment led to decreased content of saturated fatty acids in phosphatidylethanolamines. In conclusion, statin treatment resulted in the decreased content of cholesterol and diphosphatidylglycerol associated with the increased content of sphingolipids in the rat brain tissue. As cholesterol and sphingolipids are important components of brain membranes, the observed alterations in the composition brain lipids might be involved in genesis of neurological and mental symptoms following statin therapy.

Polyunsaturated fatty acids in total lipid and phospholipids of chilean scallop Argopecten purpuratus (L.) larvae: effects of diet and temperature

The composition of lipids and fatty acids of larval scallop Argopecten purpuratus were determined when cultured at one of two temperatures and using one of the three algal diets. Larvae grown at 12 °C had the lowest values of phosphatidylcholine (PC) and highest values of cholesterol and steryl esters (SE). The ratio of triacylglycerol (TAG)/cholesterol was affected by temperature but not by diet and the lowest values were observed in larvae grown at 12 °C. By using the ratio of TAG/cholesterol as an index of larval condition, the best condition was observed at the begining of the experiment, before feeding, with values of 3.9 and 2.9 in eggs and D-larvae, respectively. The best culture conditions for larval scallop from this point of view was a temperature of 19 °C and a diet of Isochrysis galbana grown at 25 °C while the poorest condition was observed in larvae cultured at 12 °C and 19 °C and fed the mixture of Isochrysis aff galbana (clone T- Iso) high-protein and Chaetoceros neogracile high-protein (IH/GH diet). However, no significant differences in the growth rate and survival of larvae fed different diets were detected. I. galbana grown at 25 °C had no detectable percentage of arachidonic acid (ARA; 20:4 n−6), but larvae grew well and ARA was detected in PC and phosphatidylethanolamine (PE) in similar quantities to other diets. This suggests ARA may not be essential during early life stages of larval Chilean scallops. Total lipids and PC of larvae were affected by the diet in their ratio of docosahexaenoic acid (DHA; 22:6 n−3)/eicosapentaenoic acid (EPA; 20:5 n−3), but PE composition was highly conserved and was unaffected by diet. DHA/EPA ratio in total lipid and in PC showed highest values when larvae were fed I. galbana grown at 25 °C. Temperature affected the total highly unsaturated fatty acids (HUFA) in total lipids, PC and PE of larvae. In all cases values were lowest when larvae were cultured at 12 °C. In addition, increased temperature increased the ratio of EPA/ARA in PC and decreased the ratio of monounsaturated fatty acids (MUFA)/saturated fatty acids in PE. The ratio of n−6/ n−3 PUFA was constant in total lipid, PE and PC of larval scallops regardless of temperature or diet.

Human Group IVC Phospholipase A2(cPLA2γ): ROLES IN THE MEMBRANE REMODELING AND ACTIVATION INDUCED BY OXIDATIVE STRESS

To create the unique properties of a certain cellular membrane, both the composition and the metabolism of membrane phospholipids are key factors. Phospholipase A(2) (PLA(2)), with hydrolytic enzyme activities at the sn-2 position in glycerophospholipids, plays critical roles in maintaining the phospholipid composition as well as producing bioactive lipid mediators. In this study we examined the contribution of a Ca(2+)-independent group IVC PLA(2) isozyme (cPLA(2)gamma), a paralogue of cytosolic PLA(2)alpha (cPLA(2)alpha), to phospholipid remodeling. The enzyme was localized in the endoplasmic reticulum and Golgi apparatus, as seen using green fluorescence fusion proteins. Electrospray ionization mass spectrometric analysis of membrane extracts revealed that overexpression of cPLA(2)gamma increased the proportion of polyunsaturated fatty acids in phosphatidylethanolamine, suggesting that the enzyme modulates the phospholipid composition. We also found that H(2)O(2) and other hydroperoxides induced arachidonic acid release in cPLA(2)gamma-transfected human embryonic kidney 293 cells, possibly through the tyrosine phosphorylation pathway. Thus, we propose that cPLA(2)gamma is constitutively expressed in the endoplasmic reticulum and plays important roles in remodeling and maintaining membrane phospholipids under various conditions, including oxidative stress.

Phosphatidic acid–phosphatidylethanolamine interaction and apocytochrome c translocation across model membranes

The translocation of apocytochrome c (apocyt.c) across large unilamellar vesicles (LUVs) constructed from mixtures of anionic and zwitterionic phospholipids, phosphatidylethanolamine (PE) and phosphatidylcholine (PC), has been studied. It was shown that the import ratio of horse heart apocyt.c in LUVs composed of phosphatidic acid (PA) combined with PE and PC (62±10%) was much higher than that in LUVs made of PE and PC plus any other acidic phospholipid species (20±5%). This feature was shared by tuna heart and chicken heart apocyt.c. In addition, the greater efficiency of the PA/PE/PC system versus others in facilitating apocyt.c translocation was maintained using synthetic anionic phospholipids with the same acyl chains. Besides, apocyt.c induces more leakage of entrapped fluorescein sulphonate (FS) from the interior of PA/PC/PE vesicles compared with phosphatidylglycerol (PG)/PC/PE ones. By measuring the intrinsic fluorescence emission spectrum and the accessibility of the preprotein to the fluorescence quencher, acrylamide, differences could be detected in the conformational changes of apocyt.c as a consequence of its interaction with PA/PE/PC and PG/PE/PC vesicles, respectively. Particularly notable is that PE is indispensable for the PA/PE/PC system to most efficiently facilitate apocyt.c translocation across the model membranes. With the fraction of PE increasing from 0 to 30 mol%, the translocation efficiency of apocyt.c as well as its ability to induce FS efflux was significantly enhanced in PA-containing LUVs, whereas this was not observed in the case of replacement of PA by PG or phosphatidylserine. It is also interesting to note that in LUVs containing PA, dioleoyl-PE, but not dielaidoyl-PE, can exert such influences, indicative of the role of non-bilayer formation propensity. On the basis of these results it is postulated that PA might increase the bilayer-destabilizing effects of PE, and hence increase the translocation efficiency of apocyt.c and its leakage-induction ability.