Cell Membrane Fatty Acid Research Articles

Biochemical and molecular effects of glycine betaine treatment on membrane fatty acid metabolism in cold stored peaches

The effect of glycine betaine (GB) treatment on chilling injury (CI), cell membrane integrity and membrane fatty acid metabolism in peach fruit during storage were investigated using biochemical and transcriptomic analysis in this study. The results showed that GB treatment alleviated the CI by suppressing lipoxygenase (LOX), phospholipase D (PLD) and lipase gene expression and enzyme activities, resulting in higher levels of unsaturated fatty acids and degree of unsaturation. In addition, this study suggested that GB treatment could inhibit the release of cytochrome C and caspase-3 activity, thus suppressing cell breakdown and contributing to membrane function. Moreover, transcriptome analysis revealed that genes related to fatty acid biosynthesis and desaturation were enhanced, while genes related to fatty acid degradation and activation of caspases were suppressed by GB treatment. Therefore, GB treatment could maintain normal cell membrane structure and function through upregulating membrane fatty acid biosynthesis and desaturation metabolism and downregulating caspase activation to alleviate CI in peaches.

Synthesis of docosahexaenoic acid-loaded silver nanoparticles for improving endothelial dysfunctions in experimental diabetes.

To investigate the ability of docosahexaenoic acid (DHA)-loaded silver nanoparticles (AgNPs) in facilitating the incorporation of DHA in the cell membrane, improve cell membrane structure, and attenuate endothelial dysfunction in experimental diabetes. DHA/AgNPs were prepared using a nanoprecipitation technique. Fifty male albino rats were used in this study; 10 of them were served as the control group and 40, as the experimental groups, were injected with streptozotocin. Then, the experimental groups were subdivided into diabetic, diabetic treated with DHA, diabetic treated with AgNPs, and diabetic treated with DHA/AgNPs groups. DHA/AgNPs have small spherical size as proved from ultraviolet-visible spectroscopy, transmission electron microscope, dynamic light scattering, and scanning electron microscope techniques. Cell membrane cholesterol and triglycerides showed a significant elevation in the diabetic group compared to the control, but treatment with DHA and DHA/AgNPs caused a significant reduction in both. Treatment with AgNPs and DHA/AgNPs caused a significant improvement in asymmetric dimethylarginine and nitric oxide levels compared to the diabetic group. Cell membrane fatty acids showed that omega-6 polyunsaturated fatty acids (PUFAs) were significantly elevated, while omega-3 PUFA were significantly reduced in the diabetic group compared to the control. There is a significant improvement in the levels of fatty acids in all groups after treatment with DHA, silver, or DHA/AgNPs. DHA/AgNPs are potent agents for the improvement of diabetic complication and endothelial dysfunction in experimental diabetes.

Functionalization of Elongated Tetrahexahedral Au Nanoparticles and Their Antimicrobial Activity Assay.

Gold nanoparticles are inert for the human body, and therefore, they have been functionalized to provide them with antibacterial properties. Here, elongated tetrahexahedral (ETHH) Au nanoparticles were synthesized, characterized, and functionalized with lipoic acid (LA), a natural antioxidant with a terminal carboxylic acid and a dithiolane ring, to generate ETHH-LA Au nanoparticles. The antioxidant activity of Au nanoparticles was investigated in vitro, showing that LA enhances the 2,2-diphenyl-1-picrylhydrazyl free-radical scavenging and Fe3+ ion reducing activity of ETHH-LA at higher amounts. The antimicrobial propensities of the nanoparticles were investigated against Gram-positive ( Bacillus subtilis) and Gram-negative ( Escherichia coli) bacteria through propidium iodide assay as well as disk diffusion assay. ETHH-LA Au nanoparticles showed significantly higher antimicrobial activity against B. subtilis compared with E. coli. Furthermore, ETHH-LA Au nanoparticles also showed significantly better antimicrobial activity against both bacterial strains when compared with ETHH. ETHH Au nanoparticles also bring about the oxidation of bacterial cell membrane fatty acids and produce lipid peroxides. ETHH-LA showed higher lipid peroxidation potential than that of ETHH against both bacteria tested. The hemolytic potential of Au nanoparticles was investigated using human red blood cells and ETHH-LA showed reduced hemolytic activity than that of ETHH. The cytotoxicity of Au nanoparticles was investigated using human cervical cancer cells, HeLa, and ETHH-LA Au nanoparticles showed reduced cytotoxicity than that of ETHH. Taken together, LA enhances the antimicrobial activity of ETHH Au nanoparticles and Au nanoparticles interact with the bacteria through electrostatic interactions as well as hydrophobic interactions and damage the bacterial cell wall followed by oxidation of cell membrane fatty acids.

Membrane fatty acids composition and fluidity modification in Salmonella Typhimurium by culture temperature and resistance under pulsed electric fields

SummaryEffects of various growth temperatures on cell membrane fatty acid composition of Salmonella Typhimurium (S. Typhimurium) and the resistance to Pulsed Electric Fields (PEF) treatments, as well as PEF combining with mild‐thermal (35, 45, 55 °C) treatments were investigated. Results indicated that the PEF resistance of S. Typhimurium at stationary phase was varied markedly at different growth temperatures. S. Typhimurium grown at 45 °C exhibited greater PEF resistance than cells grown at a lower temperature. Alteration of membrane fatty acid composition decreased in the unsaturated to saturated fatty acids ratio (UFA/SFA) and increased in cyclopropane fatty acids (CFA) proportion as growth temperature increased. It was found that the PEF resistance of S. Typhimurium at stationary phase was in a membrane fluidity dependent manner. Thermal combined PEF treatment improved the PEF lethality which indicated that the PEF resistance of S. Typhimurium was greatly affected by the fluidity of cytomembrane.

New Insights on the Nutrition Status and Antioxidant Capacity in Multiple Sclerosis Patients.

Background: Multiple sclerosis (MS) is a multifactorial disease with unknown etiology. It is assumed to result from interplay between genetic and environmental factors, including nutrition. We hypothesized that there are differences in nutritional parameters between MS patients and healthy controls. Methods: We examined 63 MS patients and 83 healthy controls. Nutritional status was determined by a dietary questionnaire, blood tests, quantification of cell membrane fatty acids, and serum antioxidant capacity. Results: We found that MS patients consumed a more limited diet compared with the healthy group, indicated by a lower average of 31 nutrients and by consumption levels of zinc and thiamine below the recommended daily intake. Both consumption and measured iron values were significantly lower in MS patients, with the lowest measures in the severe MS group. Long saturated fatty acids (>C16) were significantly lower in MS patients, while palmitic and palmitoleic acids were both higher. Serum total antioxidant capacity was significantly lower in the MS group compared with healthy controls, with the lowest measures in patients with severe MS. Conclusions: This study points to a possible correlation between nutritional status and MS. Understanding the clinical meaning of these findings will potentially allow for the development of future personalized dietary interventions as part of MS treatment.

Influence of changes in microbial cell membrane composition on isotopic fractionation of nitrate during denitrification

Pure cultures of Thauera aromatica were stressed by the addition of the toxic solvents 1-octanol and 4-chlorophenol causing adaptive modifications in their cell-membrane fatty acid composition. At the same time, we investigated the isotopic fractionation in δ15N-NO3- during denitrification. We observed a change in the degree of saturation (DoS) of the bacteria as a reaction to solvent stress and a higher degree of saturation was directly correlated to the concentration of solvents in the cell membrane. The enrichment factor ε15N-NO3- during denitrification showed a linear dependency to the DoS as well as to the membrane solvent concentration. Denitrifying bacteria thus may express less negative ε15N-NO3- when they are exposed to environmental stress that changes their cell membrane composition.

Altered Red Blood Cell Membrane Fatty Acid Profile in Cancer Patients.

The fatty acid (FA) composition of red blood cell (RBC) membrane phospholipids of cancer patients can reflect tumor status, dietary intakes, and cancer type or therapy. However, the characteristic membrane profiles have so far not yet defined as a potential biomarker to monitor disease evolution. The present work provides the first evidence of cancer metabolic signatures affecting cell membranes that are independent of nutritional habits. From the Oncology Outpatient Unit of the Onkologikoa hospital, two groups of cancer patients (n = 54) and healthy controls (n = 37) were recruited, and mature RBCs membrane phospholipids were analyzed for FA profiling (GC-MS). Dietary habits were evaluated using a validated food frequency questionnaire. The adjusted Analysis of Covariance Test (ANCOVA) model revealed cancer patients to have a lower relative percentage of saturated fatty acids (SFA) (C16:0 (5.7%); C18:0 (15.9%)), and higher monounsaturated fatty acids (MUFA) (9c-C18:1 (12.9%) and 11c-C18:1 (54.5%)), compared to controls. In line with this, we observe that the desaturase enzymatic index (delta-9 desaturase (Δ9D), +28.3%) and the membrane saturation index (SI = SFA/MUFA; −27.3%) were similarly modulated. Polyunsaturated fatty acids (PUFA) families showed an increase of n-6 C18:2 and C20:3 (15.7% and 22.2% respectively), with no differences in n-6 C20:4 and n-3 PUFA (docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)). Importantly, these changes were found independent of foods and fat intakes from the diet. The membrane lipid profile in RBC was useful to ascertain the presence of two main metabolic signatures of increased desaturation activity and omega-6 in cancer patients, statistically independent from dietary habits.

Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing.

Climate change is one of many ongoing human-induced environmental changes, but few studies consider interactive effects between multiple anthropogenic disturbances. In coastal sub-arctic heathland, we quantified the impact of a factorial design simulating extreme winter warming (WW) events (7 days at 6–7°C) combined with episodic summer nitrogen (+N) depositions (5 kg N ha-1) on plant winter physiology, plant community composition and ecosystem CO2 fluxes of an Empetrum nigrum dominated heathland during 3 consecutive years in northern Norway. We expected that the +N would exacerbate any stress effects caused by the WW treatment. During WW events, ecosystem respiration doubled, leaf respiration declined (-58%), efficiency of Photosystem II (Fv/Fm) increased (between 26 and 88%), while cell membrane fatty acids showed strong compositional changes as a result of the warming and freezing. In particular, longer fatty acid chains increased as a result of WW events, and eicosadienoic acid (C20:2) was lower when plants were exposed to the combination of WW and +N. A larval outbreak of geometrid moths (Epirrita autumnata and Operophtera brumata) following the first WW led to a near-complete leaf defoliation of the dominant dwarf shrubs E. nigrum (-87%) and Vaccinium myrtillus (-81%) across all experimental plots. Leaf emergence timing, plant biomass or composition, NDVI and growing season ecosystem CO2 fluxes were unresponsive to the WW and +N treatments. The limited plant community response reflected the relative mild winter freezing temperatures (-6.6°C to -11.8°C) recorded after the WW events, and that the grazing pressure probably overshadowed any potential treatment effects. The grazing pressure and WW both induce damage to the evergreen shrubs and their combination should therefore be even stronger. In addition, +N could have exacerbated the impact of both extreme events, but the ecosystem responses did not support this. Therefore, our results indicate that these sub-arctic Empetrum-dominated ecosystems are highly resilient and that their responses may be limited to the event with the strongest impact.

Effect of ethanol adaption on the inactivation of Acetobacter sp. by pulsed electric fields

The effects of low concentrations of ethanol (3% to 9%, v/v) on cell membrane fatty acid composition, membrane lipid conformation, membrane fluidity and pulsed electric fields (PEF) resistance of Acetobacter sp. in the stationary phase were investigated. Results showed that the growth of Acetobacter sp. was inhibited, and analysis of gas chromatography–mass spectrometry, Raman spectroscopy and fluorescence polarization indicated that membrane fluidity of Acetobacter sp. cells was significantly increased by modifying membrane fatty acid composition and membrane lipid conformation after exposure to ethanol. Moreover, results showed that cells cultivated in the medium with relatively high ethanol concentrations were more vulnerable to PEF. For example, the inactivation of Acetobacter sp. (109 CFU/mL) cultivated with 9% ethanol by PEF (20.0 kV/cm, 6.0 ms) could reach 5.17 log, significantly higher than those cultivated without ethanol (3.22 log). This was confirmed by morphological analysis, showing various changes on the cell surface after PEF treatment. Acetobacter sp. is one of spoilage microorganisms in winemaking, and it is able to convert the ethanol produced by yeasts into acetic acid and thereby increase volatile acidity in wine. In this study, the effect of ethanol as a growth substrate on PEF resistance in Acetobacter sp. cells was investigated. Results here reported will contribute to better understand the influencing mechanisms of ethanol on the inactivation of Acetobacter sp. cells by PEF treatment and further develop the application of PEF for inactivating acetic acid bacteria (AAB) in the wine industry.

Antimicrobial Activity of Phenyllactic Acid Against Enterococcus faecalis and Its Effect on Cell Membrane.

3-Phenyllactic acid (PLA) was reported to have an effective antimicrobial activity. This study evaluated the antimicrobial activity of PLA against foodborne Enterococcus faecalis and its effect on cell membrane. The minimum concentration of PLA to inactivate E. faecalis in brain heart infusion broth was 5 mg/mL. PLA solutions of 5 and 10 mg/mL can inactivate E. faecalis population ≥6 log CFU/mL within 60 and 30 min, respectively. The cell membranes of most E. faecalis cells were damaged after PLA treatment according to the images of scanning electron microscopy and transmission electron microscopy. The differences in the regions of cell membrane protein, fatty acid, and polysaccharide were revealed by Fourier transform infrared spectroscopy, which further indicated cell membrane damages. The cell membrane permeability was increased when the concentration of PLA treatment was increased in the membrane permeability assays. Finally, almost all bacterial cells were damaged after treatment with 10 mg/mL PLA for 30 min, further confirmed by flow cytometry analysis. This study concluded that PLA is effective in inactivating E. faecalis cells through the leakage of intracellular components caused by cell membrane damage.

Variations in cellular membrane fatty acid composition ofEscherichia coliin resistance to pulsed electric fields induced by eugenol

Eugenol (EUG; 4-allyl-2-methoxyphenol) is a natural antibacterial component from essential oil. The effects of EUG on cell membrane fatty acid composition, membrane fluidity and resistance to pulsed electric field (PEF) of Escherichia coli ATCC 8,739 (E. coli) were investigated. Results indicated that the PEF resistance of E. coli decreased as EUG concentration increased, which may be related to the alterations in membrane fatty acid composition and fluidity. Gas chromatography−mass spectrometry and micro-Raman spectroscopy showed that EUG increased membrane fluidity by notably increasing the proportion of unsaturation fatty acids and simultaneously decreasing the content of cyclic fatty acids. These results revealed that PEF resistance of E. coli was influenced by EUG due to alterations of fatty acid composition and membrane fluidity. Practical applications Pulsed electric field (PEF), as a widely used non-thermal sterilization technology, has gained much attention and increasingly focused on improving the efficiency to inactivate micro-organisms. Eugenol (EUG; 4-allyl-2-methoxyphenol) derived from cloves is a natural phenol essential oil and exhibits several pharmacological properties such as being an antimicrobial. Our results revealed the underlying mechanism that EUG reduced PEF resistance of E. coli cells and contributed to achieve better understanding of microbial inactivation by PEF. Therefore, a new route for the application of eugenol to improve the efficiency of PEF in the food industry was created.

Effects of Hypoxia and Bed Rest on Markers of Cardiometabolic Risk: Compensatory Changes in Circulating TRAIL and Glutathione Redox Capacity.

In chronic diseases, hypoxia and physical inactivity are associated with atherosclerosis progression. In contrast, a lower mortality from coronary artery disease and stroke is observed in healthy humans residing at high altitude in hypoxic environments. Eleven young, male volunteers completed the following 10-day campaigns in a randomized order: hypoxic ambulatory, hypoxic bed rest and normoxic bed rest. Before intervention, subjects were evaluated in normoxic ambulatory condition. Normobaric hypoxia was achieved in a hypoxic facility simulating 4000 m of altitude. Following hypoxia, either in bed rest or ambulatory condition, markers of cardiometabolic risk shifted toward a more atherogenic pattern consisting of: (a) lower levels of total HDL cholesterol and HDL2 sub-fraction and decreased hepatic lipase; (b) activation of systemic inflammation, as determined by C-reactive protein and serum amyloid A; (c) increased plasma homocysteine; (d) decreased delta-5 desaturase index in cell membrane fatty acids, a marker of insulin sensitivity. Bed rest and hypoxia additively decreased total HDL and delta-5 desaturase index. In parallel to the pro-atherogenic effects, hypoxia activated selected anti-atherogenic pathways, consisting of increased circulating TNF-related apoptosis-inducing ligand (TRAIL), a protective factor against atherosclerosis, membrane omega-3 index and erythrocyte glutathione availability. Hypoxia mediated changes in TRAIL concentrations and redox glutathione capacity (i.e., GSH/GSSG ratio) were greater in ambulatory conditions (+34 ± 6% and +87 ± 31%, respectively) than in bed rest (+17 ± 7% and +2 ± 27% respectively). Hypoxia-induced cardiometabolic risk is blunted by moderate level of physical activity as compared to bed rest. TRAIL and glutathione redox capacity may contribute to the positive interaction between physical activity and hypoxia.Highlights:– Hypoxia and bed rest activate metabolic and inflammatory markers of atherogenesis.– Hypoxia and physical activity activate selected anti-atherogenic pathways.– Hypoxia and physical activity positive interaction involves TRAIL and glutathione.

FADS Polymorphism, Omega-3 Fatty Acids and Diabetes Risk: A Systematic Review.

The role of n-3 long chain polyunsaturated fatty acids (LC n-3 PUFA) in reducing the risk of type 2 diabetes (T2DM) is not well established. The synthesis of LC n-3 PUFA requires fatty acid desaturase enzymes, which are encoded by the FADS gene. It is unclear if FADS polymorphism and dietary fatty acid intake can influence plasma or erythrocyte membrane fatty acid profile and thereby the risk of T2DM. Thus, the aim of this systematic review was to assess the current evidence for an effect of FADS polymorphism on T2DM risk and understand its associations with serum/erythrocyte and dietary LC n-3 PUFA. A systematic search was performed using PubMed, Embase, Cochrane and Scopus databases. A total of five studies met the inclusion criteria and were included in the present review. This review identified that FADS polymorphism may alter plasma fatty acid composition and play a protective role in the development of T2DM. Serum and erythrocyte LC n-3 PUFA levels were not associated with risk of T2DM, while dietary intake of LC n-3 PUFA was associated with lower risk of T2DM in one study only. The effect of LC n-3 PUFA consumption on associations between FADS polymorphism and T2DM warrants further investigation.

Regulation of Hepatic Glucose and Lipid Metabolism by the Acetyl‐CoA Hydrolase Acyl‐CoA Thioesterase 12 (Acot12)

Acetyl‐CoA is a key determinant of gluconeogenesis and lipid biosynthesis in the liver, and the sources of acetyl‐CoA within hepatocytes are well defined. Acot12 is a cytosolic enzyme that catalyzes the hydrolysis of acetyl‐CoA into acetate plus CoASH. In addition to its enzymatic domains, Acot12 also contains a steroidogenic acute regulatory protein‐related lipid transfer (START) domain, which functions as lipid sensor. Although enriched in the liver, the biological functions of Acot12 remain unknown. We hypothesized that Acot12 activity may suppress hepatic glucose production and lipogenesis.MethodsTo overexpress Acot12 in C57BL/6J mice and in primary cultured mouse hepatocytes, we generated Acot12.Ad adenovirus and used null.Ad adenovirus as the control. Expression levels of Acot12 were assessed by real‐time PCR, immunoblot analysis and immunofluorescence. Tolerance tests to glucose (GTTs), pyruvate (PTTs) and insulin (ITTs) were performed after 6, 16 and 4 h fasting periods, respectively. Plasma and hepatic lipid concentrations were measured using enzymatic assays. Rates of basal and cAMP‐stimulated rates of gluconeogenesis from pyruvate plus lactate, as well as de novo lipogenesis from acetate were determined in cultured hepatocytes. Fatty acid oxidation rates in liver tissue and primary hepatocytes were quantified from to the conversion of 14C‐palmitate into 14C‐acid soluble metabolites and 14C‐CO2.ResultsAcot12.Ad increased Acot12 mRNA and elevated protein levels by 10‐fold in mouse livers. Acot12 overexpression improved glucose tolerance, as evidence by decreased values of area‐under‐the curve (AUC) during the course of the GTTs. Decreased AUC values were also observed during PTTs, which reflect rates of gluconeogenesis. No differences were observed for ITTs, which largely reflect peripheral insulin responsiveness. Acot12 overexpression reduced hepatic phospholipids and plasma cholesterol concentrations. In primary hepatocytes, overexpression of Acot12 reduced basal and cAMP‐stimulated rates of glucose production, as well as rates of de novo lipogenesis. In addition, Acot12 overexpression increased fatty acid oxidation rates in both liver tissue and primary hepatocytes. This correlated with higher mRNA expression levels of the plasma membrane fatty acid transporter CD36 and of mitochondrial CPT1a, which promotes fatty acid uptake for oxidation.ConclusionsTaken together, our findings reveal that Acot12 activity in the liver suppresses both glucose production and lipogenesis. Increased rates of hepatocellular fatty acid uptake and oxidation presumably reflect compensatory mechanisms directed towards the repletion of TCA cycle intermediates that support glucose and lipid biosynthesis. We speculate that Acot12 regulates hepatic nutrient metabolism by controlling cytosolic acetyl‐CoA concentrations within the liver.Support or Funding InformationThis work was supported by NIH grants DK048873, DK056626 and DK103046, as well as the American Liver Foundation.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Determination of Flavonoid, Tannin and Vitamin C Content from Methanol Extract Wrapping Stone Banana (Musa brachycarpa), Ketip Banana (Musa Paradisiaca Forma Typiaca) and Kepok Banana (Musa acuminata)

Research has been done to investigate the levels of flavanoid, tannin, and vitamin C of methanol extract of Stone banana (Musa brachycarpa), Ketip banana (Musa paradisiaca forma typiaca ), and Kepok banana (Musa acuminata). Jukut Ares is a Balinese traditional cuisine frequently served in any events of celebrations. The use of young stems of such banana varieties as the main raw materials in the process of making jukut ares has not been scientifically elucidated. Antioxidants are compounds with ability to inhibit oxidation-related reactions due to free radicals that cause disturbance of saturated fatty acids of cell membrane, blood vessels, DNA, as well as adipose tissues which lead to occurrence of various diseases. Plants components will have antioxidant activities if they contain compounds (phenol and flavanoid) with ability to scavenge free radicals. Tannin is a water based phenolic compound and vitamin C is also a water based vitamin that play important roles in preventing us from various diseases. Extraction was conducted by applying maceration method and to investigate the levels of flavanoid, spectrophotometric UV vis with aluminum chloride (AlCl3) was applied. The level of vitamin C of the materials was conducted by Iodine titration method, while the level of tannin was determind by applying spectrophotometri. The results showed that methanol extract of Ketip banana stem contained the highest level of flavanoid with a quantity of 53.13 mg/100gr QE, and this was followed by stone banana (36.28) and kepok banana (32.07) The highest vitamin C level was indicated in the extract of ketip banana (418.32 mg/100gr), which is followed by kapok banana and stone banana. In the calculation of tannin content, pisang ketip showed the highest level, while pisang batu contained the lowest level of tannin.

Effect of Omega-3 Fatty Acid Supplementation on Oxylipins in a Routine Clinical Setting.

Omega-6 polyunsaturated fatty acid (n-6 PUFA) is the predominant polyunsaturated fatty acid (PUFA), especially in Western diet. A high omega-6/omega-3 ratio in Western diets is implicated in the development of cardiovascular diseases and inflammatory processes. Studies in animal models and in humans have demonstrated beneficial effects of omega-3 PUFA (n-3 PUFA) in a variety of diseases, including cardiac arrhythmias and inflammatory diseases, as well as breast and colon cancer. The molecular mechanisms underlying the effects of n-3 PUFA are still not well understood. Possible mechanisms include competition between n-3 and n-6 PUFAs at the cyclooxygenase (COX) and lipoxygenase (LOX) and cytochrome P450 levels, and subsequent formation of oxylipins with specific anti-inflammatory or anti-arrhythmic effects. In this study, we report the impact of routine long-term treatment with prescription-grade n-3 PUFA (either 840 mg or 1680 mg per day) on blood cell membrane fatty acid composition, as well as plasma oxylipin patterns, in a patient population with severe hyperlipidemia and cardiovascular disease who are on standard lipid-lowering and cardioprotective medications. Lipidomics analyses were performed by LC/ESI-MS/MS. Supplementation led to a dose-dependent increase in n-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the blood cell fraction. We also observed a dose-dependent increase in EPA- and DHA-derived epoxy metabolites, whereas the effect of n-3 PUFA supplementation on LOX-dependent EPA- and DHA-derived hydroxy metabolites was less pronounced, with a tendency towards lower metabolites in subjects with higher n-3 PUFA levels. These data thus generally confirm effects of n-3 PUFA supplementation observed previously in healthy individuals. Additionally, they indicate a suppressive effect of high n-3 PUFA supplementation on the formation of LOX metabolites in the context of concomitant aspirin medication.

Accumulation of Hydroxyl Fatty Acid in Lactobacillus sakei Y-20 Cells Cultivated under Stress Conditions and Expression of Fatty Acid Hydroxylase

ABSTRACTFruit aroma lactones such as γ-dodecalactone contained in whisky are produced by yeast from precursor hydroxyl fatty acids created by lactic acid bacteria from fatty acids. Application of the aroma lactone in brewery or whisky/spirits production requires knowledge of the conditions of hydroxylation by enzyme activity and its expression in bacteria. Hydroxyl fatty acid was produced more efficiently at 15°C than at 30°C. The 10-hydroxyl stearic acid (10-HSA), which accounts for more than approximately 60% of fatty acids in cell membranes, is converted from oleic acid (OA). However, the hydroxylase (FAHase) did not convert other fatty acids to hydroxyl fatty acid. The fatty acid hydroxylase in the strain was able to react only with OA. Although the strain was able to grow in the medium containing OA under low pH, alcohol, and metal ion stress conditions, 10-HSA accumulated only to a slight degree. The expression of FAHase in the medium containing OA at 15°C was 2.38 times that of the medium without OA. The expression of FAHase in the pH 2.0 condition was 1.7 times that of the control. Furthermore, in a medium containing iron ions, the expression of FAHase was more than twice that of the control.

CgMED3 Changes Membrane Sterol Composition To Help Candida glabrata Tolerate Low-pH Stress.

Candida glabrata is a promising microorganism for organic acid production. The present study aimed to investigate the role of C. glabrata Mediator complex subunit 3 (CgMed3p) in protecting C. glabrata under low-pH conditions. To this end, genes CgMED3A and CgMED3B were deleted, resulting in the double-deletion Cgmed3ABΔ strain. The final biomass and cell viability levels of Cgmed3ABΔ decreased by 64.5% and 35.8%, respectively, compared to the wild-type strain results at pH 2.0. In addition, lack of CgMed3ABp resulted in selective repression of a subset of genes in the lipid biosynthesis and metabolism pathways. Furthermore, C18:1, lanosterol, zymosterol, fecosterol, and ergosterol were 13.2%, 80.4%, 40.4%, 78.1%, and 70.4% less abundant, respectively, in the Cgmed3ABΔ strain. In contrast, the concentration of squalene increased by about 44.6-fold. As a result, membrane integrity, rigidity, and H+-ATPase activity in the Cgmed3ABΔ strain were reduced by 62.7%, 13.0%, and 50.3%, respectively. In contrast, overexpression of CgMED3AB increased the levels of C18:0, C18:1, and ergosterol by 113.2%, 5.9%, and 26.4%, respectively. Moreover, compared to the wild-type results, dry cell weight and pyruvate production increased, irrespective of pH buffering. These results suggest that CgMED3AB regulates membrane composition, which in turn enables cells to tolerate low-pH stress. We propose that regulation of CgMed3ABp may provide a novel strategy for enhancing low-pH tolerance and increasing organic acid production by C. glabrataIMPORTANCE The objective of this study was to investigate the role of Candida glabrata Mediator complex subunit 3 (CgMed3ABp) and its regulation of gene expression at low pH in C. glabrata We found that CgMed3ABp was critical for cellular survival and pyruvate production during low-pH stress. Measures of the levels of plasma membrane fatty acids and sterol composition indicated that CgMed3ABp could play an important role in regulating homeostasis in C. glabrata We propose that controlling membrane lipid composition may enhance the robustness of C. glabrata for the production of organic acids.

Change in the Lipid Transport Capacity of the Liver and Blood during Reproduction in Rats.

To support the high energetic demands of reproduction, female mammals display plasticity in many physiological processes, such as the lipid transport system. Lipids support the energy demands of females during reproduction, and energy and structural demands of the developing offspring via the placenta in utero or milk during the suckling period. We hypothesized that key proteins supporting lipid transport in reproductive females will increase during pregnancy and lactation, but drop to non-reproductive levels shortly after reproduction has ended. We compared the relative protein levels of liver-type cytosolic fatty acid transporter (L-FABPc), plasma membrane fatty acid transporter (FABPpm), fatty acid translocase (FAT/CD36) in the liver, a key site of lipid storage and synthesis, and free fatty acid transporter albumin and triglyceride transporter [represented by apolipoprotein B (apoB)] levels in serum in reproductive Sprague-Dawley rats during late pregnancy, peak-lactation, and 1-week post-lactation as well as in non-reproductive rats. We found that all lipid transporter levels were greater in pregnant rats compared to non-reproductive rats. Lactating rats also showed higher levels of FAT/CD36 and FABPpm than non-reproductive rats. Moreover, all fat transporters also dropped back to non-reproductive levels during post-lactation except for FAT/CD36. These results indicate that fat uptake and transport capacities in liver cells are elevated during late gestation and lactation. Liver lipid secretion is up-regulated during gestation but not during lactation. These data supported the plasticity of lipid transport capacities in liver and blood during reproductive stages.

Effects of multi-walled carbon nanotubes with various diameters on bacterial cellular membranes: Cytotoxicity and adaptive mechanisms

The effect of multi-walled carbon nanotubes (MWNTs) with different diameters on the destruction degree toward cellular membranes of bacterial has been explored by investigating the viability of bacteria and the change of composition and surface properties in cellular membranes with the exposure of MWNTs. The atrazine degrading bacteria Acinetobacter lwoffii DNS32 (DNS32) is chosen as the model species and Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) are selected as the comparison specie. Bacterial viability testing shows that MWNTs with smaller diameters generally display stronger toxicity to bacteria and also influenced by many factors including the electrostatic repulsion between MWNTs and bacteria and bacteria types. Interestingly, bacteria can self-regulate as an adaptive response to the toxicity of MWNTs, notably, DNS32 strain presents the adaptive responses when cultivated with MWNT60-100 through modification of fatty acids in cell membranes, but does not exhibit similar responses when exposed to MWNT10-20. This result may be related to the interference from MWNT10-20, which exceeds the cellular ability to self-repair. Transmission electron microscopy (TEM) images and flow cytometric analysis of bacteria exposed to MWNTs reveal that the destruction of cell membrane in the DNS32 strain is more serious than that in the B. subtilis, indicating that electrostatic repulsion between the material and bacteria leading to the decrease of direct contact may be the primary factor that reduces the impacts from MWNTs.