Interaction of glucose and long chain fatty acids (C18) on antioxidant defences and free radical damage in porcine vascular smooth muscle cells in vitro.

Aims/hypothesis: Abnormalities of glucose and fatty acid metabolism in diabetes are believed to contribute to the development of oxidative stress and the long term vascular complications of the disease therefore the interactions of glucose and long chain fatty acids on free radical damage and endogenous antioxidant defences were investigated in vascular smooth muscle cells. Methods: Porcine vascular smooth muscle cells were cultured in 5 mmol/l or 25 mmol/l glucose for ten days. Fatty acids, stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2) and gamma-linolenic acid (18:3) were added with defatted bovine serum albumin as a carrier for the final three days. Results. Glucose (25 mmol/l) alone caused oxidative stress in the cells as evidenced by free radical-mediated damage to DNA, lipids, and proteins. The addition of fatty acids (0.2 mmol/l) altered the profile of free radical damage; the response was J-shaped with respect to the degree of unsaturation of each acid, and oleic acid was associated with least damage. The more physiological concentration (0.01 mmol/l) of gamma-linolenic acids was markedly different in that, when added to 25 mmol/l glucose it resulted in a decrease in free radical damage to DNA, lipids and proteins. This was due to a marked increase in levels of the antioxidant, glutathione, and increased gene expression of the rate-limiting enzyme in glutathione synthesis, gamma-glutamylcysteine synthetase. Conclusion/Interpretation: The results clearly show that glucose and fatty acids interact in the production of oxidative stress in vascular smooth muscle cells.

Fatty acids as gatekeepers of immune cell regulation

Fatty acids have diverse roles in all cells. They are important as a source of energy, as structural components of cell membranes, as signalling molecules and as precursors for the synthesis of eicosanoids. Recent research has suggested that the organization of fatty acids into distinct cellular pools has a particularly important role in cells of the immune system and that forms of lipid trafficking exist, which are as yet poorly understood. This Review examines the nature and regulation of cellular lipid pools in the immune system, their delivery of fatty acids or fatty acid derivatives to specific locations and their potential role in health and disease.

Acute ingestion of a meal rich in n-3 polyunsaturated fatty acids results in rapid gastric emptying in humans

Background: n-3 Polyunsaturated fatty acids (PUFAs) have proven benefits for both the development of atherosclerosis and inflammatory conditions. The effects on atherosclerosis may be partly mediated by the observed reduction in fasting and postprandial triacylglycerol concentrations after both acute and chronic n-3 PUFA ingestion. Objective: The aim of this study was to assess gastric emptying and gastrointestinal hormone release after the consumption of mixed meals rich in n-3 PUFAs or other classes of fatty acids. Design: Ten healthy women (aged 50–62 y) completed 4 separate study visits in a single-blind, randomized design. On each occasion, subjects consumed 40 g oil rich in either saturated fatty acids, monounsaturated fatty acids, n-6 PUFAs, or n-3 PUFAs as part of a mixed meal. [1-13C]Octanoic acid (100 mg) was added to each oil. Gastric emptying was assessed by a labeled octanoic acid breath test, and concentrations of gastrointestinal hormones and plasma lipids were measured. Results: Recovery of 13C in breath was enhanced after n-3 PUFA ingestion (P < 0.005). The cholecystokinin response after the n-3 PUFA meal was significantly delayed (P < 0.001), and the glucagon-like peptide 1 response was significantly reduced (P < 0.05). Conclusion: The inclusion of n-3 PUFAs in a meal alters the gastric emptying rate, potentially as the result of changes in the pattern of cholecystokinin and glucagon-like peptide 1 release.

Incremental effect of a calcium salt of cis-monounsaturated fatty acids supplement on milk fatty acid composition in cows fed maize silage-based diets

In most Western countries, saturated fatty acid (SFA) intake exceeds recommended levels, which is considered a risk factor for cardiovascular disease (CVD). As milk and dairy products are major contributors to SFA intake in many countries, recent research has focused on sustainable methods of producing milk with a lower saturated fat concentration by altering dairy cow diets. Human intervention studies have shown that CVD risk can be reduced by consuming dairy products with reduced SFA and increased cis-monounsaturated fatty acid (MUFA) concentrations. This milk fatty acid profile can be achieved by supplementing dairy cow diets with cis-MUFA-rich unsaturated oils. However, rumen exposure of unsaturated oils also leads to enhanced milk trans fatty acid (TFA) concentrations. Because of concerns about the effects of TFA consumption on CVD, feeding strategies that increase MUFA concentrations in milk without concomitant increases in TFA concentration are preferred by milk processors. In an attempt to limit TFA production and increase the replacement of SFA by cis-MUFA, a preparation of rumen-protected unsaturated oils was developed using saponification with calcium salts. Four multiparous Holstein-Friesian cows in mid-late lactation were used in a 4 × 4 Latin square design with 21-d periods to investigate the effect of incremental dietary inclusion of a calcium salt of cis-MUFA product (Ca-MUFA; 20, 40, and 60 g/kg of dry matter of a maize silage-based diet), on milk production, composition, and fatty acid concentration. Increasing Ca-MUFA inclusion reduced dry matter intake linearly, but no change was observed in estimated ME intake. No change in milk yield was noted, but milk fat and protein concentrations were linearly reduced. Supplementation with Ca-MUFA resulted in a linear reduction in total SFA (from 71 to 52 g/100 g of fatty acids for control and 60 g/kg of dry matter diets, respectively). In addition, concentrations of both cis- and trans-MUFA were increased with Ca-MUFA inclusion, and increases in other biohydrogenation intermediates in milk fat were also observed. The Ca-MUFA supplement was very effective at reducing milk SFA concentration and increasing cis-MUFA concentrations without incurring any negative effects on milk and milk component yields. However, reduced milk fat and protein concentrations, together with increases in milk TFA concentrations, suggest partial dissociation of the calcium salts in the rumen

Effect of polyunsaturated fatty acids on the fecundity of the Amazon river prawn Macrobrachium amazonicum (Heller, 1862)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Activity of Extracts and Fatty Acids of Canavalia ensiformis (Leguminosae) Against the Symbiotic Fungus of the Leaf-Cutting Ants Atta sexdens

The inhibitory effect of leaves extracts of Carnavalia ensiformis on the development of the symbiotic fungus of the leaf-cutting ants Atta sexdens (Forel) was evaluated. The hexane extract showed highest activity at concentration of 1000 μg/mL. Chromatographic separations of this extract have led to the isolation of a mixture of fatty acids which showed the same activity of the crude extract.

Toxicity of straight-chain fatty acids to leaf-cutting ants Atta sexdens rubropilosa (Hymenoptera: Formicidae) and the symbiotic fungus Leucoagaricus gongylophorus

This work determined toxicity and attractiveness of straight-chain fatty acids (C 5 to C 12) to Atta sexdens rubropilosa (Forel) workers. The effect to the symbiotic fungus, Leucoagaricus gongylophorus (Singer) Möller, was also tested with the fatty acids C 6 to C 12. A strong mortality of leaf-cutting ants that were fed with an artificial diet containing fatty acids C to C at concentrations above 1.0 mg.ml -1 was observed. Rice flakes impregnated with solutions of these fatty acids were repellent to leaf-cutting ants. Contact experiments showed that treatments with C 6 and C 7 at concentration of 100 mg.ml -1 significantly reduced the survival rate of leaf-cutting ants. The fatty acids C 8 to C 11 were toxic to leaf-cutting ants when topically tested at concentration of 200 mg.ml -1. In relation to the fungus' bioassays, the fatty acids C 6 to C 12 at concentration of 0.1 mg.ml -1 inhibited 100% of the fungal development. Although when the concentration was reduced by half no inhibition effects were observed. The results showed that straight-chain fatty acids have desirable properties for controlling leaf-cutting ants since they directly interfere with both organisms of the symbiotic relationship. The potential of fatty acids as well as ways to control leaf-cutting ants with these compounds are discussed in this article.

Sources of omega-6 fatty acids do not alter the rumen degradation and transit of fibre from dairy cow diets

The objective of this study was to evaluate the behaviour of fibre in the digestive tract on the basis of the passage kinetics of forage and concentrate particles in cows fed different omega-6 fatty-acid sources. The scientific hypothesis of this study was that omega-6 fatty acids do not interfere with the digestion of fibre in the diets of dairy cows. Five primiparous lactating Holstein cows were used in the experiment. The experimental diets were: control (C), ground soyabean (GS), cottonseed (CS), soyabean oil (SO), calcium salts of fatty acids (CSFA). The global mean estimates for the parameters of passage rate (gamma) were 0.038 and 0.055 h(-1) for forage and concentrate, respectively. The only significant effect with respect to the passage rate was a high negative correlation between the concentrate passage rate and dry matter intake. There was less undegradable neutral detergent fibre (NDF) in treatments without added lipid. Dietary supplementation with lipid sources does not alter the kinetic parameters of roughage and concentrate particle passage or in vitro NDF degradation. Sources of omega-6 fatty acids do not alter the rumen degradation and transit of fibre.

Identification and characterization of an enzyme involved in the elongation of n-6 and n-3 polyunsaturated fatty acids

The enzymes that are involved in the elongation of fatty acids differ in terms of the substrates on which they act. To date, the enzymes specifically involved in the biosynthesis of polyunsaturated fatty acids have not yet been identified. In an attempt to identify a gene(s) encoding an enzyme(s) specific for the elongation of γ-linolenic acid (GLA) (18:3n-6), a cDNA expression library was made from the fungus Mortierella alpina. The cDNA library constructed in a yeast expression vector was screened by measuring the expressed elongase activity [conversion of GLA to dihomo-GLA (20:3n-6)] from an individual yeast clone. In this report, we demonstrate the isolation of a cDNA (GLELO) whose encoded protein (GLELOp) was involved in the conversion of GLA to dihomo-GLA in an efficient manner (60% conversion). This cDNA contains a 957-nucleotide ORF that encodes a protein of 318 amino acids. Substrate specificity analysis revealed that this fungal enzyme acted also on stearidonic acid (18:4n-3). This report identifies and characterizes an elongase subunit that acts specifically on the two Δ6-desaturation products, 18:3n-6 and 18:4n-3. When this GLELO cDNA was coexpressed with M. alpina Δ5-desaturase cDNA in yeast, it resulted in the conversion of GLA to arachidonic acid (20:4n-6) as well as the conversion of stearidonic acid to eicosopentaenoic acid (20:5n-3). Thus, this GLELO gene may play an critical role in the bio-production of both n-6 and n-3 polyunsaturated fatty acids.

Unsaturated fatty acids inhibit transcription of the sterol regulatory element-binding protein-1c (SREBP-1c) gene by antagonizing ligand-dependent activation of the LXR

Sterol regulatory element-binding protein-1c (SREBP-1c) enhances transcription of genes encoding enzymes of unsaturated fatty acid biosynthesis in liver. SREBP-1c mRNA is known to increase when cells are treated with agonists of liver X receptor (LXR), a nuclear hormone receptor, and to decrease when cells are treated with unsaturated fatty acids, the end products of SREBP-1c action. Here we show that unsaturated fatty acids lower SREBP-1c mRNA levels in part by antagonizing the actions of LXR. In cultured rat hepatoma cells, arachidonic acid and other fatty acids competitively inhibited activation of the endogenous SREBP-1c gene by an LXR ligand. Arachidonate also blocked the activation of a synthetic LXR-dependent promoter in transfected human embryonic kidney-293 cells. In vitro, arachidonate and other unsaturated fatty acids competitively blocked activation of LXR, as reflected by a fluorescence polarization assay that measures ligand-dependent binding of LXR to a peptide derived from a coactivator. These data offer a potential mechanism that partially explains the long-known ability of dietary unsaturated fatty acids to decrease the synthesis and secretion of fatty acids and triglycerides in livers of humans and other animals.

Rapid differentiation of isomeric lipids by photodissociation mass spectrometry of fatty acid derivatives

RATIONALE Both traditional electron ionization and electrospray ionization tandem mass spectrometry have demonstrated limitations in the unambiguous identification of fatty acids. In the former case, high electron energies lead to extensive dissociation of the radical cations from which little specific structural information can be obtained. In the latter, conventional collision-induced dissociation (CID) of even-electron ions provides little intra-chain fragmentation and thus few structural diagnostics. New approaches that harness the desirable features of both methods, namely radical-driven dissociation with discrete energy deposition, are thus required. METHODS Herein we describe the derivatization of a structurally diverse suite of fatty acids as 4-iodobenzyl esters (FAIBE). Electrospray ionization of these derivatives in the presence of sodium acetate yields abundant [M+Na]+ ions that can be mass-selected and subjected to laser irradiation (=266nm) on a modified linear ion-trap mass spectrometer. RESULTS Photodissociation (PD) of the FAIBE derivatives yields abundant radical cations by loss of atomic iodine and in several cases selective dissociation of activated carboncarbon bonds (e.g., at allylic positions) are also observed. Subsequent CID of the [M+NaI]center dot+ radical cations yields radical-directed dissociation (RDD) mass spectra that reveal extensive carboncarbon bond dissociation without scrambling of molecular information. CONCLUSIONS Both PD and RDD spectra obtained from derivatized fatty acids provide a wealth of structural information including the position(s) of unsaturation, chain-branching and hydroxylation. The structural information obtained by this approach, in particular the ability to rapidly differentiate isomeric lipids, represents a useful addition to the lipidomics tool box. Copyright (c) 2013 John Wiley & Sons, Ltd.

Capacity of fatty acid profiles and substrate utilization patterns to describe differences in soil microbial communities associated with increased salinity or alkalinity at three locations in South Australia

Fatty acid methyl ester (FAME) profiles, together with Biolog substrate utilization patterns, were used in conjunction with measurements of other soil chemical and microbiological properties to describe differences in soil microbial communities induced by increased salinity and alkalinity in grass/legume pastures at three sites in SE South Australia. Total ester-linked FAMEs (EL-FAMEs) and phospholipid-linked FAMEs (PL-FAMEs), were also compared for their ability to detect differences between the soil microbial communities. The level of salinity and alkalinity in affected areas of the pastures showed seasonal variation, being greater in summer than in winter. At the time of sampling for the chemical and microbiological measurements (winter) only the affected soil at site 1 was significantly saline. The affected soils at all three sites had lower organic C and total N concentrations than the corresponding non-affected soils. At site 1 microbial biomass, CO 2-C respiration and the rate of cellulose decomposition was also lower in the affected soil compared to the non-affected soil. Biomarker fatty acids present in both the EL- and PL-FAME profiles indicated a lower ratio of fungal to bacterial fatty acids in the saline affected soil at site 1. Analysis of Biolog substrate utilization patterns indicated that the bacterial community in the affected soil at site 1 utilized fewer carbon substrates and had lower functional diversity than the corresponding community in the non-affected soil. In contrast, increased alkalinity, of major importance at sites 2 and 3, had no effect on microbial biomass, the rate of cellulose decomposition or functional diversity but was associated with significant differences in the relative amounts of several fatty acids in the PL-FAME profiles indicative of a shift towards a bacterial dominated community. Despite differences in the number and relative amounts of fatty acids detected, principal component analysis of the EL- and PL-FAME profiles were equally capable of separating the affected and non-affected soils at all three sites. Redundancy analysis of the FAME data showed that organic C, microbial biomass, electrical conductivity and bicarbonate-extractable P were significantly correlated with variation in the EL-FAME profiles, whereas pH, electrical conductivity, NH 4-N, CO 2-C respiration and the microbial quotient were significantly correlated with variation in the PL-FAME profiles. Redundancy analysis of the Biolog data indicated that cation exchange capacity and bicarbonate-extractable K were significantly correlated with the variation in Biolog substrate utilization patterns.

The metabolism of phenolic acids in the rat

Some of the enzyme systems in the formation of p-hydroxybenzoate from tyrosine have been studied in the rat liver in vitro. The conversion of p-hydroxycinnamate into p-hydroxybenzoate, which was found in rat liver mitochondria showed a number of differences when compared with the b-oxidation of fatty acids. Studies with p-hydroxy[U-14C]cinnamate indicated that 14CO2 was released during the formation of p-hydroxybenzoate. The formation of p-hydroxycinnamate from tyrosine of p-hydroxyphenyl-lactate could not be demonstrated in vitro. The interconversion of p-hydroxycinnamate and p-hydroxyphenylpropionate was demonstrated in rat liver mitochondria.

Comparative Analysis of Fatty Acid Desaturases in Cyanobacterial Genomes

Fatty acid desaturases are enzymes that introduce double bonds into the hydrocarbon chains of fatty acids. The fatty acid desaturases from 37 cyanobacterial genomes were identified and classified based upon their conserved histidine-rich motifs and phylogenetic analysis, which help to determine the amounts and distributions of desaturases in cyanobacterial species. The filamentous or N-2-fixing cyanobacteria usually possess more types of fatty acid desaturases than that of unicellular species. The pathway of acyl-lipid desaturation for unicellular marine cyanobacteria Synechococcus and Prochlorococcus differs from that of other cyanobacteria, indicating different phylogenetic histories of the two genera from other cyanobacteria isolated from freshwater, soil, or symbiont. Strain Gloeobacter violaceus PCC 7421 was isolated from calcareous rock and lacks thylakoid membranes. The types and amounts of desaturases of this strain are distinct to those of other cyanobacteria, reflecting the earliest divergence of it from the cyanobacterial line. Three thermophilic unicellular strains, Thermosynechococcus elongatus BP-1 and two Synechococcus Yellowstone species, lack highly unsaturated fatty acids in lipids and contain only one Delta 9 desaturase in contrast with mesophilic strains, which is probably due to their thermic habitats. Thus, the amounts and types of fatty acid desaturases are various among different cyanobacterial species, which may result from the adaption to environments in evolution. Copyright (c) 2008 Xiaoyuan Chi et al.

Fatty acids and immune function: new insights into mechanisms

Fatty acids are known to play diverse roles in immune cells. They are important as a source of energy, as structural components of cell membranes, as signaling molecules and as precursors for the synthesis of eicosanoids and similar mediators. Recent research has suggested that the localization and organisation of fatty acids into distinct cellular pools has a direct influence on the behaviour of a number of proteins involved in immune cell activation, including those associated with T cell responses, antigen presentation and fatty acid-derived inflammatory mediator production. This article reviews these studies and places them in the context of existing literature in the field. These studies indicate the existence of several novel mechanisms by which altered fatty acid availability can modulate immune responses and impact upon clinical outcomes