Total Membrane Lipids Research Articles

Total membrane lipid assay (MLA): simple and practical quantification of exosomes based on efficient membrane-specific dyes unaffected by proteins

MLA uses two fluorescent dyes for ratiometric determination of exosomes' membrane lipids.

CO2 permeability and carbonic anhydrase activity of rat cardiomyocytes.

To determine the CO2 permeability (PCO2 ) of plasma membranes of cardiomyocytes. These cells were chosen because heart possesses the highest rate of O2 consumption/CO2 production in the body. Cardiomyocytes were isolated from rat hearts using the Langendorff technique. Cardiomyocyte suspensions exhibited a vitality of 2-14% and were studied by the previously described mass spectrometric 18 O-exchange technique deriving PCO2 . We showed by mass spectrometry and by carbonic anhydrase (CA) staining that non-vital cardiomyocytes are free of CA and thus do not contribute to the mass spectrometric signal, which is determined exclusively by the fully functional vital cardiomyocytes. Lysed cardiomyocytes yielded an intracellular CA activity for vital cells of 5070; that is, the rate of CO2 hydration inside the cell is accelerated 5071-fold. Using this number, analyses of the mass spectrometric recordings from cardiomyocyte suspensions yield a PCO2 of 0.10 cm s-1 (SD ± 0.06, n = 15) at 37 °C. In comparison with the PCO2 of other cells, this value is quite high and about identical to that of the human red cell membrane. As no major protein CO2 channels such as aquaporins 1 and 4 are present in rat cardiac sarcolemma, the high PCO2 of this membrane is likely due to its low cholesterol content of about 0.2 (mol cholesterol)·(mol total membrane lipids)-1 . Previous work predicted a PCO2 of ≥0.1 cm s-1 from this level of cholesterol. We conclude that the low cholesterol establishes a PCO2 high enough to render the membrane resistance to CO2 diffusion almost negligible, even under conditions of maximal O2 consumption of the heart.

A Small Cohort Omega-3 PUFA Supplement Study: Implications of Stratifying According to Lipid Membrane Incorporation in Cardiac Surgical Patients.

Epidemiological studies and randomised clinical trials (RCTs) report disparate findings in relation to omega-3 polyunsaturated fatty acids (n-3 PUFA) benefit for cardiac patients. With RCTs interpretation is potentially confounded by background n-3 PUFA intake. The goal of this pilot, small cohort, pre-surgical supplementation study was to evaluate postoperative atrial fibrillation (AF) and cardiac molecular expression profiles employing two data analysis approaches - by treatment randomisation and by stratification using measured n-3 PUFA. Patients (n=20) received 3g/day of fish or placebo oil (FO vs PO) in a double blind randomised protocol prior to elective coronary artery graft and valve surgery. Groups were matched for age, gender, and mean treatment duration (∼20 days). Resected atrial myocardium was sampled for assay of viability metabolic markers, and blood obtained for erythrocyte membrane lipid measurement. There was substantial overlap of cell membrane n-3 PUFA content across PO and FO groups, and no group treatment effects on AF incidence or myocardial molecular marker levels were detected. In contrast, data stratification using membrane n-3 PUFA content (at 8% total membrane lipid) achieved significant separation of patients (by n-6:n-3 PUFA ratio), a significant differential cardiac expression of the marker peroxisomal proliferator-activated receptor, but no difference in AF incidence. This small n-3 PUFA case study demonstrates that the same cohort may yield differing findings when evaluated using randomisation or stratification approaches based on direct molecular measures in cell membranes.

Carbon and Acyl Chain Flux during Stress-induced Triglyceride Accumulation by Stable Isotopic Labeling of the Polar Microalga Coccomyxa subellipsoidea C169

Deriving biofuels and other lipoid products from algae is a promising future technology directly addressing global issues of atmospheric CO2 balance. To better understand the metabolism of triglyceride synthesis in algae, we examined their metabolic origins in the model species, Coccomyxa subellipsoidea C169, using stable isotopic labeling. Labeling patterns arising from [U-13C]glucose, 13CO2, or D2O supplementation were analyzed by GC-MS and/or LC-MS over time courses during nitrogen starvation to address the roles of catabolic carbon recycling, acyl chain redistribution, and de novo fatty acid (FA) synthesis during the expansion of the lipid bodies. The metabolic origin of stress-induced triglyceride was found to be a continuous 8:2 ratio between de novo synthesized FA and acyl chain transfer from pre-stressed membrane lipids with little input from lipid remodeling. Membrane lipids were continually synthesized with associated acyl chain editing during nitrogen stress, in contrast to an overall decrease in total membrane lipid. The incorporation rates of de novo synthesized FA into lipid classes were measured over a time course of nitrogen starvation. The synthesis of triglycerides, phospholipids, and galactolipids followed a two-stage pattern where nitrogen starvation resulted in a 2.5-fold increase followed by a gradual decline. Acyl chain flux into membrane lipids was dominant in the first stage followed by triglycerides. These data indicate that the level of metabolic control that determines acyl chain flux between membrane lipids and triglycerides during nitrogen stress relies primarily on the Kennedy pathway and de novo FA synthesis with limited, defined input from acyl editing reactions.

Loss of Inositol Phosphorylceramide Sphingolipid Mannosylation Induces Plant Immune Responses and Reduces Cellulose Content in Arabidopsis.

Glycosylinositol phosphorylceramides (GIPCs) are a class of glycosylated sphingolipids found in plants, fungi, and protozoa. These lipids are abundant in the plant plasma membrane, forming ∼25% of total plasma membrane lipids. Little is known about the function of the glycosylated headgroup, but two recent studies have indicated that they play a key role in plant signaling and defense. Here, we show that a member of glycosyltransferase family 64, previously named ECTOPICALLY PARTING CELLS1, is likely a Golgi-localized GIPC-specific mannosyl-transferase, which we renamed GIPC MANNOSYL-TRANSFERASE1 (GMT1). Sphingolipid analysis revealed that the Arabidopsis thaliana gmt1 mutant almost completely lacks mannose-carrying GIPCs. Heterologous expression of GMT1 in Saccharomyces cerevisiae and tobacco (Nicotiana tabacum) cv Bright Yellow 2 resulted in the production of non-native mannosylated GIPCs. gmt1 displays a severe dwarfed phenotype and a constitutive hypersensitive response characterized by elevated salicylic acid and hydrogen peroxide levels, similar to that we previously reported for the Golgi-localized, GIPC-specific, GDP-Man transporter GONST1 (Mortimer et al., 2013). Unexpectedly, we show that gmt1 cell walls have a reduction in cellulose content, although other matrix polysaccharides are unchanged.

Sulfoquinovosyldiacylglycerol has an Essential Role in Thermosynechococcus elongatus BP-1 Under Phosphate-Deficient Conditions.

Anionic lipids, sulfoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG), are major classes of the thylakoid membrane lipids in cyanobacteria and plant chloroplasts. PG is essential for growth and photosynthesis of cyanobacteria, algae and plants, but the requirement for SQDG differs even among cyanobacterial species. Although SQDG and PG can compensate each other in part presumably to maintain proper balance of anionic charge in lipid bilayers, the functional relationship of these lipids is largely unknown. In this study, we inactivated the sqdB gene, encoding a UDP-sulfoquinovose synthase and involved in SQDG biosynthesis, in Thermosynechococcus elongatus BP-1. In wild-type cells, PG accounted for only approximately 3.5 mol% of total membrane lipids, but its content was substantially increased along with complete loss of SQDG in the sqdB mutant. Under phosphate (Pi)-sufficient conditions, the growth rate and PSII activity were slightly lower in sqdB than in wild-type cells. In addition, the formation of PSI trimers and PSII dimers and energy transfer in phycobilisomes were perturbed in the mutant. Under Pi-deficient conditions, the growth of sqdB cells was severely impaired, with a decrease in PSII activity. PG supplementation could partially rescue the defective growth and PSII activity of Pi-deficient sqdB cells but fully recovered the impaired growth of the pgsA mutant of T. elongatus, which is deficient in PG biosynthesis. These data suggest that SQDG has a specific role in the growth and photosynthesis of T. elongatus, which cannot be complemented by PG, particularly under Pi-deficient conditions.

Oral administration of fumonisin B1 and T-2 individually and in combination affects hepatic total and mitochondrial membrane lipid profile of rabbits.

Weaned rabbits were fed diets contaminated with 2mg/kg diet T-2 toxin alone, or 10mg/kg diet fumonisin B1 (FB1) alone, and both toxins in combination (2 + 10mg/kg, respectively) compared to a toxin-free control diet. Samplings were performed after 4 weeks (blood and liver). Bodyweight of T-2-fed group was lower after 4 weeks; the liver weight was increased dramatically (threefold of control). Liver total phospholipids (PLs) provided slight alterations in the fatty acid (FA) composition; all three toxin-treated groups showed a decrease in palmitoleic acid (C16:1 n7) proportion. In the liver mitochondrial PL FA composition, margaric acid (C17:0) proportion decreased in the separated toxin treatments compared to the combined setting. Oleic acid (C18:1 n9) proportion was increased and arachidonic acid (C20:4 n6) was decreased in the FB1-treated group, while docosapentaenoic acid (C22:5 n3) was decreased in the separated treatments. The total monounsaturation was significantly higher in the FB1 group's mitochondrial PL FA profile. After 4 weeks, all toxin treatments decreased the blood plasma reduced glutathione and glutathione peroxidase activity, and FB1 increased the plasma sphinganine/sphingosine ratio. Both mycotoxins seem to cross the hepatocellular and the hepatic mitochondrial membrane, without drastic membrane disruption, as assessed from the PL FA composition, but inducing detectable lipid peroxidation.

Submergence induced changes of molecular species in membrane lipids in Arabidopsis thaliana

The composition of membrane lipids is sensitive to environmental stresses. Submergence is a type of stress often encountered by plants. However, how the molecular species of membrane lipids respond to submergence has not yet been characterised. In this study, we used a lipidomic approach to profile the molecular species of membrane lipids in whole plants of Arabidopsis thaliana that were completely submerged for three days. The plants survived one day of submergence, after which, we found that the total membrane lipids were only subtly decreased, showing significant decreases of monogalactosyldiacylglycerol (MGDG) and phosphatidylcholine (PC) and an increase of phosphatidic acid (PA); however, the basic lipid composition was retained. In contrast, three days of submergence caused plants to die, and the membranes deteriorated via the rapid loss of 96% of lipid content together with a 229% increase in PA. The turnover of molecular species from PG and MGDG to PA indicated that submergence-induced lipid changes occurred through PA-mediated degradation. In addition, molecular species of extraplastidic PG degraded sooner than plastidic ones, lyso-phospholipids exhibited various patterns of change, and the double-bond index (DBI) remained unchanged until membrane deterioration. Our results revealed the unique changes of membrane lipids upon submergence and suggested that the major cause of the massive lipid degradation could be anoxia.

Calcium Promotes the Formation of Syntaxin 1 Mesoscale Domains through Phosphatidylinositol 4,5-Bisphosphate

Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a minor component of total plasma membrane lipids, but it has a substantial role in the regulation of many cellular functions, including exo- and endocytosis. Recently, it was shown that PI(4,5)P2 and syntaxin 1, a SNARE protein that catalyzes regulated exocytosis, form domains in the plasma membrane that constitute recognition sites for vesicle docking. Also, calcium was shown to promote syntaxin 1 clustering in the plasma membrane, but the molecular mechanism was unknown. Here, using a combination of superresolution stimulated emission depletion microscopy, FRET, and atomic force microscopy, we show that Ca2+ acts as a charge bridge that specifically and reversibly connects multiple syntaxin 1/PI(4,5)P2 complexes into larger mesoscale domains. This transient reorganization of the plasma membrane by physiological Ca2+ concentrations is likely to be important for Ca2+-regulated secretion.

English

Cardiovascular disease and oxidative stress are involved in aging. Aging causes many alterations in myochardial functions and metabolism. The aim of this study was to investigate the effect of aging on heart functions, total antioxidant capacity and membrane lipid composition and the effects of oral administration of ginger and lipoic acid for 30 days. The levels of serum lactate dehydrogenase, creatine kinase and heart antioxidant capacity exhibited marked alterations in normal senile female rats. The treatment of ginger and lipoic acid for 30 days improved these alterations. Furthermore, the relationship between membrane lipid composition and aging was detected. There were significant increases in lauric and myristic acids and significant decrease in arachidic acid in senile rats. On the other hand, the unsaturated fatty acids (olic, linoleic, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were significantly decreased. Ginger treatment showed significant decreases in saturated fatty acids. In lipoic acid treated group, there was a significant improvement in the level of unsaturated fatty acids (EPA and DHA) as compared with normal senile female rats. In conclusion, ginger and lipoic acid may have ameliorative effect of heart functions, total antioxidant capacity and membrane free fatty acids in old female rats. Key words: Ginger, lipoic acid, senile, heart, antioxidant, free fatty acids.

Dietary docosahexaenoic acid supplementation reduces SERCA Ca2+ transport efficiency in rat skeletal muscle

Docosahexaenoic acid (DHA) can reduce the efficiency and increase the energy consumption of Na+/K+-ATPase pump and mitochondrial electron transport chain by promoting Na+ and H+ membrane permeability, respectively. In skeletal muscle, the sarco(endo) plasmic reticulum Ca2+-ATPase (SERCA) pumps are major contributors to resting metabolic rate. Whether DHA can affect SERCA efficiency remains unknown. Here, we examined the hypothesis that dietary supplementation with DHA would reduce Ca2+ transport efficiency of the SERCA pumps in skeletal muscle. Total lipids were extracted from enriched sarcoplasmic reticulum (SR) membranes that were isolated from red vastus lateralis skeletal muscles of rats that were either fed a standard chow diet supplemented with soybean oil or supplemented with DHA for 8 weeks. The fatty acid composition of total SR membrane lipids and the major phospholipid species were determined using electrospray ionization mass spectrometry (ESI-MS). After 8 weeks of DHA supplementation, total SR DHA content was significantly elevated (control, 4.1±1.0% vs. DHA, 9.9±1.7%; weight percent of total fatty acids) while total arachidonic acid was reduced (control, 13.5±0.4% vs. DHA-fed, 9.4±0.2). Similar changes in these fatty acids were observed in phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol, altogether indicating successful incorporation of DHA into the SR membranes post-diet. As hypothesized, DHA supplementation reduced SERCA Ca2+ transport efficiency (control, 0.018±0.0002 vs. DHA-fed, 0.014±0.0009) possibly through enhanced SR Ca2+ permeability (ionophore ratio: control, 2.8±0.2 vs. DHA-fed, 2.2±0.3). Collectively, our results suggest that DHA may promote skeletal muscle-based metabolism and thermogenesis through its influence on SERCA.

Physiological modifications of seston in response to physicochemical gradients within Lake Superior

In September 2011, we investigated the distribution and composition of dissolved and particulate phosphorus (P) pools throughout Lake Superior, a large P‐limited freshwater ecosystem. Average seston particulate P (PP) concentrations in the deep chlorophyll maximum (DCM; 85 ± 28 nmol L−1) were significantly greater than in the epilimnion (63 ± 22 nmol L−1). In contrast, average particulate organic carbon (POC) : PP (mol : mol) ratios showed the opposite pattern (DCM = 303 : 1 vs. epilimnion = 455 : 1). Mean seston nucleic acid—P concentrations were invariant between the epilimnetic (23 ± 18 nmol L−1) and DCM (26 ± 18 nmol L−1) layers, but significantly greater concentrations of intact polar membrane—derived phospholipids were found in the DCM (6 ± 2 nmol L−1) relative to the epilimnion (4 ± 2 nmol L−1). Phospholipids were a minor proportion of PP (7–14%) and total membrane lipids (< 30%). Rather, our results suggest that microbial flora of Lake Superior substituted non‐phosphorus lipids for phospholipids. In the nitrogen (N)—rich waters, N‐based betaine lipids dominated (39–42%) the lipid pool, and concentrations were significantly greater in the P‐poor epilimnetic seston. Sulfolipids were also abundant and significantly greater in the epilimnion (7 ± 2 nmol L−1) than in the DCM (4 ± 2 nmol L−1), despite low sulfate concentrations relative to marine environments. Our results demonstrate for the first time the importance of plankton producing non‐phosphorus lipids for phospholipids as a strategy for reducing cellular P inventories in lacustrine regimes.

Characterization of Thermoplasma Species Cultured from Sampling on Tangkuban Perahu, Indonesia

Archaea is an organisme with unique feature because of its ability to inhabit an extremophyle conditions. Our expeditions to Tangkuban Perahu, West Java aimed to obtain archaealstrains from the solfatara fields located in Domas crater. From the samples, we intended to culture Thermoplasma species growing around 55 °C below pH 2, which until now have not yet been fully characterized. We collected five samples from mud holes with temperatures from 52 °C to 57 °C and pH below 2. In serial cultures of up to 8 transfers in Freundt’s medium we grew tetraetherlipid synthesizing Thermoplasma species as documented by phase contrast microscope. Total membrane lipid extracts were analysed by thin layer chromatography; the pattern matched total lipid extracts from Thermoplasma acidophilum DSM 1728 membranes. For confirmation, 16S rDNA identification performing PCR and sequencing were carried-out. Analysis using BLAST showed T. acidophilum identities as the highest similarity of 99%, followed by T. volcanium, also with99% similarity (ANKF776908 and ANKF776909). This is the first report of culturing cell-wall-less thermoacidophilicarchaea,in particular Thermoplasma species in Indonesian laboratories.

Age-related characteristics of erythrocyte membrane microviscosity in experimental cardiosclerosis

Age-related changes in the microviscosity coefficient and polarity in the zones of lipid-lipid and lipid-protein contacts have been studied in erythrocyte membranes of 4- and 12-month-old rats (group 1, n = 20, and group 2, n = 20, respectively) using the pyrene lateral diffusion method. Each group included ten control animals and ten animals in which post-infarction cardiac remodeling had been induced. Increased microviscosity and polarity of annular and total membrane lipids were detected in erythrocyte membranes of 12-month-old animals. A pronounced increase in the microviscosity and polarity of erythrocyte membranes in the zone of annular and total lipids occurred in 4-month-old animals in which PICS was induced. Decreased microviscosity in the lipid bilayer and increased microviscosity in the annular lipid zone was characteristic of 12-month-old animals suffering from PICS; lipid polarity in this group was high and did not change.

Altered membrane lipid composition and functional parameters of circulating cells in cockles (Cerastoderma edule) affected by disseminated neoplasia

Membrane lipid composition and morpho-functional parameters were investigated in circulating cells of the edible cockle (Cerastoderma edule) affected by disseminated neoplasia (neoplastic cells) and compared to those from healthy cockles (hemocytes). Membrane sterol levels, phospholipid (PL) class and subclass proportions and their respective fatty acid (FA) compositions were determined. Morpho-functional parameters were evaluated through total hemocyte count (THC), mortality rate, phagocytosis ability and reactive oxygen species (ROS) production. Both morpho-functional parameters and lipid composition were profoundly affected in neoplastic cells. These dedifferentiated cells displayed higher THC (5×), mortality rate (3×) and ROS production with addition of carbonyl cyanide m-chloro phenylhydrazone (1.7×) but lower phagocytosis ability (½×), than unaffected hemocytes. Total PL amounts were higher in neoplastic cells than in hemocytes (12.3 and 5.1nmol×10-6 cells, respectively). However, sterols and a particular subclass of PL (plasmalogens; 1-alkenyl-2-acyl PL) were present in similar amounts in both cell type membranes. This led to a two times lower proportion of these membrane lipid constituents in neoplastic cells when compared to hemocytes (20.5% vs. 42.1% of sterols in total membrane lipids and 21.7% vs. 44.2% of plasmalogens among total PL, respectively). Proportions of non-methylene interrupted FA- and 20:1n-11-plasmalogen molecular species were the most impacted in neoplastic cells when compared to hemocytes (⅓× and ¼×, respectively). These changes in response to this leukemia-like disease in bivalves highlight the specific imbalance of plasmalogens and sterols in neoplastic cells, in comparison to the greater stability of other membrane lipid components.

Effects of CaCl2 pretreatment on antioxidant enzyme and leaf lipid content of faba bean (Vicia faba L.) seedlings under cadmium stress

In the present investigation we studied the role of CaCl2 pretreatment on physiological and biochemical characteristics in faba bean (Vicia faba L.) seedlings subjected to cadmium (Cd) stress. The seeds of faba bean were treated with H2O and 2 % CaCl2 before germination for 6 h. Primed or nonprimed (control) seeds were then germinated under increasing concentrations of Cd (0, 10, 50 and 100 μM) for 21 days. The contents of Cd, soluble protein (SP), malondialdehyde (MDA), total membrane lipid contents, fatty acid composition and the activities of superoxide dismutase (SOD EC 1.15.1.1), catalase (CAT EC 1.11.1.6), guaiacol peroxidase (GPX EC 1.11.1.7), lipoxygenase (LOX) in the seedlings leaves were tested. Exposure of the plants to Cd caused a gradual decrease in the shoot and root dry weight. Seed pretreatment with CaCl2 alleviated the negative effect of Cd on plant growth parameters. The same tendency was observed for the chlorophyll content. The level of lipid peroxidation (as indicated by MDA content) was higher in Cd-treated plants, and remained unchanged in CaCl2-pretreated plants. The same results for the total lipid content, fatty acids composition and SP level were observed. Treatment of plants with Cd drastically decreased CAT activity and caused an increase in both SOD and GPX activity. However, in CaCl2-pretreated plants, CAT activity exhibited a slight decrease under Cd treatment. An increased of SOD and GPX activity in leaves of pretreated plants was also demonstrated. The data suggest that CaCl2 pretreatment may protect faba bean seedlings against Cd toxicity.

Archaeosomes and Tetraether Lipid Liposome

Archaea have phytanyl ether lipids which is one of the characteristics that separates them from bacteria and eukaryotes. Some archaea have also unique membrane spanning tetrae- ther lipids (T EL); in Sulfolobus and Ihermoplasma species these TELmake up the majority of total membrane lipids. Archaeal lipids are able to form stable liposomal structures, both from membrane factions, mainly the polar membrane fraction, i.e. archaeosomes, or from highly purified TEL (tetraether lipid liposomes). Liposomes of the main polar lipid (MPL) from thermoacidophilic archaeon Ihermoplasma acidophilum were thoroughly inevstigat- ed. Archaeosomes and TEL liposomes exhibit extremely low proton permeability and high stability at low pH, which makes them suitable to delivery of therapeutics and vaccines via the gastro-inetestinal route. Liposomes from egg lecithin can be stabilized by incorporation of 11-12 mole% MPL. MPL liposomes show long-term shelf stability even at high tempera- tures without conservation. The size of MPL liposomes between 100 nm (unilamellar) and several gm (multilamellar) depends mainly on the method of preparation. Toxicity and mutagenicity have not been detected in toxicological screening. This is a review report on the lipid from archaea to be developed as an alternative to conventional liposome for vari- ous industrial applications, especially for pharmaceutical industry.

Lipid composition of Silybum marianum cell cultures treated with methyl jasmonate

Elicitation of cell cultures of Silybum marianum with methyl jasmonate (MeJA) increases the production and release of the secondary metabolite silymarin into the culture medium and this process seems to be dependent on phospholipase D activity and its product phosphatidic acid (PA). However, MeJA did not alter total membrane lipid content or overall fatty acid composition. A progressive increase in some galactolipids was observed with elicitation time. Phospholipids were mainly represented by phosphatidylcholine (PC) followed by phosphatidylethanolamine (PE) and phosphatidylinositol (PI). MeJA caused losses of PC species that contain two unsaturated acyl species, 36:5 and 36:6 and an increase in 36:2 species. A drop in the ratio of compounds with 18:3 in PI and PE was also observed. The presence of the lysophospholipids (LP) LPC (16:0, 18:3, 18:2, 18:1) and LPE (16:0, 18:3, 18:2, 18:1) and the high contents of PA, represented by the molecular species 34:3, 34:2 and 36:5 and 36:4, indicates high basal level of phospholipase activity in cultures and a high phospholipid turnover. MeJA treatment did not quantitatively alter these lipid classes.

Lipid composition of Silybum marianum cell cultures treated with methyl jasmonate

Elicitation of cell cultures of Silybum marianum with methyl jasmonate (MeJA) increases the production and release of the secondary metabolite silymarin into the culture medium and this process seems to be dependent on phospholipase D activity and its product phosphatidic acid (PA). However, MeJA did not alter total membrane lipid content or overall fatty acid composition. A progressive increase in some galactolipids was observed with elicitation time. Phospholipids were mainly represented by phosphatidylcholine (PC) followed by phosphatidylethanolamine (PE) and phosphatidylinositol (PI). MeJA caused losses of PC species that contain two unsaturated acyl species, 36:5 and 36:6 and an increase in 36:2 species. A drop in the ratio of compounds with 18:3 in PI and PE was also observed. The presence of the lysophospholipids (LP) LPC (16:0, 18:3, 18:2, 18:1) and LPE (16:0, 18:3, 18:2, 18:1) and the high contents of PA, represented by the molecular species 34:3, 34:2 and 36:5 and 36:4, indicates high basal level of phospholipase activity in cultures and a high phospholipid turnover. MeJA treatment did not quantitatively alter these lipid classes.

Dietary n-3 polyunsaturated fatty acids modify fatty acid composition in hepatic and abdominal adipose tissue of sucrose-induced obese rats

The fatty acid profile of hepatocytes and adipocytes is determined by the composition of the dietary lipids. It remains unclear which fatty acid components contribute to the development or reduction of insulin resistance. The present work examined the fatty acid composition of both tissues in sucrose-induced obese rats receiving fish oil to determine whether the effect of dietary (n-3) polyunsaturated fatty acids (PUFAs) on the reversion of metabolic syndrome in these rats is associated to changes in the fatty acid composition of hepatocyte and adipocyte membrane lipids. Animals with metabolic syndrome were divided into a corn-canola oil diet group and a fish oil diet group, and tissues fatty acids composition were analyzed after 6weeks of dietary treatment. Fatty acid profiles of the total membrane lipids were modified by the fatty acid composition of the diets fed to rats. N-3 PUFAs levels in animals receiving the fish oil diet plus sucrose in drinking water were significantly higher than in animals under corn-canola oil diets. It is concluded that in sucrose-induced obese rats, consumption of dietary fish oil had beneficial effects on the metabolic syndrome and that such effects would be conditioned by the changes in the n-3 PUFAs composition in hepatic and adipose tissues because they alter membrane properties and modify the type of substrates available for the production of active lipid metabolites acting on insulin resistance and obesity.