Delta-6 Desaturase Research Articles

The role of a FADS1 polymorphism in the association of fatty acid blood levels, BMI and blood pressure in young children-Analyses based on path models.

BackgroundThe recent obesity epidemic in children also showed an increase in the prevalence of hypertension. As blood pressure (BP) is associated with (long-chain) polyunsaturated fatty acids (LC PUFA), genetic variation in desaturase enzymes being involved in the synthesis of LC PUFA may be associated with BP. This study aimed to investigate the direct effects (independent of mediating variables) and indirect effects (mediated through intermediate variables) of a common variant in the FADS1 gene, rs174546, known to affect delta-5 desaturase (D5D) activity on PUFA level, body mass index (BMI) and BP.MethodsA subsample of the IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) baseline survey including 520 children aged 2 to <10 years from six European countries was included. The association between rs174546 (T<C) and BP z-score as well as the mediating effects of selected key PUFA levels (dihomo-gamma-linolenic acid, DGLA; arachidonic acid, ARA; eicosapentaenoic acid, EPA) or estimated D5D activity (D5D index) and BMI z-score were investigated through path model analyses, adjusting for sex, age, educational level of parents, family history of hypertension, lifestyle factors and blood levels of saturated and monounsaturated fatty acids, triglycerides and low density lipoprotein cholesterol. Whole blood fatty acids were measured by a validated gas chromatographic method and recorded as percentage of weight of all fatty acids detected.ResultsMinor allele carriers of the SNP rs174546 had significantly higher DGLA and lower ARA and EPA levels as well as a lower D5D index. Via ARA and BMI z-score, the polymorphism had an indirect lowering effect on systolic BP z-score for each additional T allele (standardized effect estimate -0.057, p = 0.007). For DGLA, EPA and D5D index, the indirect effects of rs174546 on systolic BP were also negative but did not reach significance. DGLA and EPA had an increasing indirect effect on systolic BP via BMI. Results for diastolic BP were in general similar but effect estimates were lower compared to systolic BP.ConclusionGenetic variation in FADS1 influences BP via ARA and BMI indicating a favorable effect of the minor allele in SNP rs174546. Thus, polymorphisms with an impact on the D5D activity may play a role for the BP level mediated through PUFA and BMI. Therefore, health effects of dietary n-6 and n-3 PUFA may vary depending on genetic FADS1 variants.

Abstract 453: FADS2 Overexpression Exacerbates Myocardial Ischemia-reperfusion Injury in Mice: Role of Mitochondria

Common FADS2 haplotypes associated with hyperactivity of its gene product, delta-6-desaturase (D6D), predict cardiovascular morbidity and mortality in humans. D6D is the rate-limiting enzyme in essential polyunsaturated fatty acid (PUFA) metabolism, but its role in the pathogenesis of cardiovascular disease is unclear. To investigate this, we generated mice with global (CMV promoter) transgenic overexpression of FADS2 and evaluated their cardiometabolic phenotype. FADS2 -tg mice exhibit mild glucose intolerance and aortic stiffening with advancing age, but no overt cardiac pathology. However, when challenged with ischemia-reperfusion (I/R) ex vivo , FADS2 -tg mouse hearts have greater infarct sizes compared to their wild-type (WT; FVB) counterparts. Mitochondrial phospholipid analyses revealed a 65% increase in the membrane arachidonic/linoleic acid (AA/LA) ratio of FADS2- tg versus WT hearts, consistent with previous work in our lab linking D6D hyperactivity with mitochondrial phospholipid remodeling and disease progression in heart failure. Thus, we hypothesized that FADS2 might exacerbate myocardial injury by altering mitochondrial responses to ischemia-reperfusion. To examine this further, mitochondria were isolated from FADS2 -tg or WT mouse hearts for functional studies following 45/90 minutes of global I/R ex vivo . FADS2- tg - I/R mitochondria exhibited lower ADP-stimulated respiration and higher H 2 O 2 emission per O 2 consumed compared to WT-I/R and non-ischemic controls , suggesting impaired cardiac energetics and greater oxidant burden following ischemia. I/R augmented Ca 2+ -induced swelling in both WT and FADS2 -tg mitochondria. This was attenuated in the presence of K + in WT, but not FADS2 -tg, implicating FADS2 -dependent alterations post-ischemic in mitochondrial K + handling. Interestingly, ischemia led to a 38% depletion of mitochondrial membrane AA in FADS2 -tg, but not WT hearts, suggesting an interaction of FADS2 and mitochondrial membrane AA liberation following ischemia. Ongoing studies in our laboratory are investigating the potentially novel links between FADS2 expression with mitochondrial phospholipases, AA signaling, and mitoK ATP channel activity in the pathogenesis of myocardial I/R injury.

Fatty Acid Composition of Plasma Phosphatidylcholine Determines Body Fat Parameters in Subjects with Metabolic Syndrome-Related Traits

This study examines the associations of fatty acids (FAs) in plasma phosphatidylcholine (PC) with the anthropometrical and biochemical characteristic of patients with metabolic syndrome (MetS)-related traits. We analyzed the FA profiles of PC in 300 persons with MetS-related traits (152 M/148F, mean age 46.9 ± 9.0 years) and in 70 healthy controls of the same age using a balanced men/women ratio and gas-liquid chromatography. Multivariate linear regression analysis was performed to determine the coefficients of determination (R2) using FA proportions of the mentioned proband characteristics. The FA composition of PC in patients with MetS traits was only associated with waist circumference (R2 = 0.27), waist-to-hip ratio (WHR; R2 = 0.41), body fat percentage (R2 = 0.62), and fat mass (R2 = 0.29). Positive associations were found for dihomo-γ-linolenic (DGLA), palmitic, stearic (SA), α-linolenic (ALA), and eicosapentaenoic acids, whereas negative associations were found for linoleic (LA), oleic, and docosapentaenoic acids. Palmitoleic acid (POA) was positively associated with waist circumference but negatively with fat percentage. In controls, significant associations were found for waist circumference (R2 = 0.51), WHR (R2 = 0.53), body fat percentage (R2 = 0.60), and fat mass (R2 = 0.34). DGLA and saturated FA (SFA) were positively associated, whereas docosahexaenoic, adrenic, and cis-vaccenic acids were negatively associated. The study group differed from controls as follows: lower concentrations of LA and total n-6 FA, higher indices of delta-9-desaturase and delta-6 desaturase activity and higher proportions of POA, SA, ALA, DGLA, and SFA. We found significant associations (R2 >0.25) of FA in plasma PC with adiposity in middle-aged persons with MetS-related traits, but not with metabolic indices.

Increasing dietary EPA and DHA influence estimated fatty acid desaturase activity in systemic organs which is reflected in the red blood cell in mice

Delta-5 (D5D) and delta-6 (D6D) desaturase are key enzymes in fatty acid (FA) metabolism. Dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may alter tissue FA composition via D5D and D6D. The purpose was to determine the relationship between dietary EPA + DHA, estimated desaturase activities of various tissues and the reflection of desaturase activity in the red blood cell (RBC). Mice were fed diets with increasing percent of energy from EPA + DHA. Phospholipid FA composition of heart, muscle, spleen, lung, adipose tissues and RBC were analysed. D5D and D6D enzyme activity estimates (EAE) were calculated as the ratio of 20:4/20:3 and 20:3/18:2, respectively. D5D EAE decreased in all tissues, except muscle, with increasing dietary EPA + DHA. RBC D5D EAE positively correlated with D5D EAE in all tissues. RBC D6D EAE positively correlated with muscle and inversely correlated with adipose D6D EAE. Our findings suggest differential influence of dietary EPA + DHA upon tissue desaturase activities.

Abstract 236: Stearoyl-CoA desaturase-1, a novel target of omega-3 fatty acids for reducing breast cancer risk in obese postmenopausal women

Abstract Preclinical and epidemiologic data suggest that a unique feature of lipogenesis in cancer cells which has received limited attention is the accumulation of monounsaturated fatty acids (MUFA) which are largely derived from saturated fatty acids (SFA) by the action of stearoyl-Co-A desaturase (SCD-1). Activation of SCD-1, a delta-9 fatty acid desaturase, is considered to be an important factor in the development of obesity and several types of cancer including breast cancer. However, no data are available on how changes in SCD-1 activity induced by potential chemopreventive agents relate to established biomarkers of breast cancer risk. To address this issue, we measured the activity of SCD-1, expressed as the ratios of palmitoleic acid (C16:ln7) to palmitic acid (C16:0) (SCD-16) and oleic acid (C18:ln9) to steric acid (C18:0) (SCD-18) in plasma samples of postmenopausal women enrolled in our recently published clinical trial (Sandhu N, et al Cancer Prev Res 9:275, 2016) designed to test the individual and combined effect of the antiestrogen Raloxifene and the omega-3 preparation Lovaza on breast density, a validated biomarker of breast cancer risk. We observed that daily administration of Lovaza (1,860 mg eicosapentaenoic [EPA] + 1,500 mg docosahexaenoic [DHA]) significantly reduced SCD-1 activity, an effect which was sustained for the two-year duration of the trial. Raloxifene, on the other hand, did not significantly alter SCD-1 activity in our subjects. SCD-1 activity was positively correlated with BMI (for SCD-16, r=0.45, p&amp;lt;01; for SCD-18, r=0.23, p&amp;lt;0.01) and paralleled changes in BMI in the same direction over the two years of the study. These findings support the role of this enzyme in the development of obesity. Importantly, decreasing levels of SCD-1 were found to be associated with a progressive reduction in breast density in obese women (BMI≥30) (for SCD-16; r=0.47, p&amp;lt;0.01; for SCD-18; r=0.36, p&amp;lt;0.05). No correlation between breast density and SCD-1 was observed in non-obese subjects (r=0.02 for SCD-16 and 0.04 for SCD-18). Our results suggest that BMI-related factors play an important role in the reduction of breast density by omega-3 fatty acids. They also indicate that SCD-1 may be a useful biomarker in future clinical trials testing the benefit of nutritional interventions in reducing obesity associated breast cancer risk. Citation Format: Andrea Manni, John P. Richie, Susann E. Schetter, Ana Calcagnotto, Neil Trushin, Cesar Aliaga, Karam El-Bayoumy. Stearoyl-CoA desaturase-1, a novel target of omega-3 fatty acids for reducing breast cancer risk in obese postmenopausal women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 236. doi:10.1158/1538-7445.AM2017-236

Effects of dietary inclusion of high concentrations of crude glycerin on meat quality and fatty acid profile of feedlot fed Nellore bulls.

Crude glycerin, the main by-product of biodiesel production, can replace dietary energy sources, such as corn. The objective of this study was to evaluate the inclusion of up to 30% of crude glycerin in dry matter (DM) of the total diets, and its effects on meat quality parameters of feedlot Nellore bulls. Thirty animals (227.7 ± 23.8 kg body weight; 18 months old) were housed in individual pens and fed 5 experimental diets, containing 0, 7.5, 15, 22.5 or 30% crude glycerin (DM basis). After 103 d (21 d adaptation) animals were slaughtered and the Longissimus muscle was collected. The characteristics assessed were chemical composition, fatty acid profile, cholesterol, shear force, pH, color, water-holding capacity, cooking loss and sensory properties. The increasing inclusion of crude glycerin in the diets did not affect the chemical composition of the Longissimus muscle (P > 0.10). A quadratic effect was observed when levels of crude glycerin were increased, on the concentration of pentadecanoic, palmitoleic and eicosenoic fatty acids in meat (P < 0.05), and on the activity of the delta-9 desaturase 16 and delta-9 desaturase 18 enzymes (P < 0.05). The addition of crude glycerin increased the gamma linolenic fatty acid concentration (P < 0.01), and altered the monounsaturated fatty acids in Longissimus muscle of animals (Pquad. < 0.05). Crude glycerin decreased cholesterol content in meat (P < 0.05), and promoted higher flavor score and greasy intensity perception of the meat (P < 0.01). The inclusion of up to 30% crude glycerin in Nellore cattle bulls`diets (DM basis) improves meat cholesterol and sensory attributes, such as flavor, without affecting significantly the physical traits, the main fatty acid concentrations and the chemical composition.

Improved \u03b3-linolenic acid production in Mucor circinelloides by homologous overexpressing of delta-12 and delta-6 desaturases

Backgroundγ-Linolenic acid (GLA) is important because of its nutritional value and medicinal applications. Although the biosynthetic pathways of some plant and microbial GLA have been deciphered, current understanding of the correlation between desaturases and GLA synthesis in oleaginous fungi is incomplete. In previous work, we found that a large amount of oleic acid (OA) had not been converted to linoleic acid (LA) or GLA in Mucor circinelloides CBS 277.49, which may be due to inadequate activities of the delta-12 or delta-6 desaturases, and thus leading to the accumulation of OA and LA. Thus, it is necessary to explore the main contributing factor during the process of GLA biosynthesis in M. circinelloides.ResultsTo enhance GLA production in M. circinelloides, homologous overexpression of delta-12 and two delta-6 desaturases (named delta-6-1 and delta-6-2, respectively) were analyzed. When delta-6 desaturase were overexpressed in M. circinelloides, up to 43% GLA was produced in the total fatty acids, and the yield of GLA reached 180 mg/l, which were, respectively, 38 and 33% higher than the control strain.ConclusionThese findings revealed that delta-6 desaturase (especially for delta-6-1 desaturase) plays an important role in GLA synthesis by M. circinelloides. The strain overexpressing delta-6-1 desaturase may have potential application in microbial GLA production.

A diet rich in omega-3 fatty acids enhances expression of soluble epoxide hydrolase in murine brain

Several studies suggest that intake of omega-3 polyunsaturated fatty acids (n3-PUFA) beneficially influences cognitive function. However, effects on the adult brain are not clear. Little is known about the impact of dietary intervention on the fatty acid profile in adult brain, the modulation in the expression of enzymes involved in fatty acid biosynthesis and metabolism as well as changes in resulting oxylipins. These questions were addressed in the present study in two independent n3-PUFA feeding experiments in mice. Supplementation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA, 1% each in the diet) for 30days to adult NMRI and C57BL/6 mice led to a distinct shift in the brain PUFA pattern. While n3-PUFAs EPA, n3 docosapentaenoic acid and DHA were elevated, many n6-PUFAs were significantly decreased (except, e.g. C20:3 n6 which was increased). This shift in PUFAs was accompanied by immense differences in concentrations of oxidative metabolites derived from enzymatic conversion of PUFAs, esp. arachidonic acid whose products were uniformly decreased, and a modulation in the activity and expression pattern of delta-5 and delta-6 desaturases. In both mouse strains a remarkable increase in the soluble epoxide hydrolase (sEH) activity (decreased epoxy-FA concentrations and epoxy-FA to dihydroxy-FA–ratios) as well as sEH expression was observed. Taking the high biological activity of epoxy-FA, e.g. on blood flow and nociceptive signaling into account, this finding might be of relevance for the effects of n3-PUFAs in neurodegenerative diseases. On any account, our study suggests a new distinct regulation of brain PUFA and oxylipin pattern by supplementation of n3-PUFAs to adult rodents.

FADS Gene Polymorphisms, Fatty Acid Desaturase Activities, and HDL-C in Type 2 Diabetes.

Polyunsaturated fatty acids (PUFA) correlate with risk of dyslipidemia and cardiovascular diseases. Fatty acid desaturase (FADS) single nucleotide polymorphisms (SNPs) modulate circulating PUFA concentrations. This study examined influence of FADS1 and FADS2 genetic variants on desaturase activities and blood lipid concentrations in type 2 diabetes patients, and further assessed their interrelationships. Selected SNPs (FADS1: rs174547, rs174548, rs174550; FADS2: rs174575, rs174576, rs174583, rs498793 and rs2727270) were genotyped in 820 type 2 diabetes patients and compared with those reported in the HapMap. Patient subgroups (n = 176) without taking lipid-lowering medicine were studied to assess influence of tag SNPs including rs174547, rs174575, rs498793 and rs2727270 on delta-5 desaturase (D5D: 20:4 (n-6)/20:3 (n-6)) and delta-6 desaturase (D6D:18:3 (n-6)/18:2 (n-6)) activities, and blood lipids. FADS1 rs174547 TT/TC/CC and FADS2 rs2727270 CC/CT/TT were significantly (p for trend < 0.05) associated with reduced HDL-C, D5D and D6D activities. Upon adjustment for confounders, D5D (p = 0.006) correlated significantly and D6D marginally (p = 0.07) correlated with increased HDL-C levels, whereas rs174547 and rs2727270 polymorphisms were not associated. D6D andD5D activities may play a role in modulating HDL-C levels in type 2 diabetes. Future studies with larger sample sizes are needed to investigate how FADS genetic variations interact with desaturase activities or PUFAs in the metabolism of lipoproteins in diabetic patients.

Phylogenomic analysis of integral diiron membrane histidine motif-containing enzymes in ciliates provides insights into their function and evolutionary relationships

The Integral Membrane Histidine Motif-containing Enzymes (IMHME) are a class of binuclear non-heme iron proteins widely distributed among prokaryotes and eukaryotes. They are characterized by a conserved tripartite motif consisting of eight to ten histidine residues. Their known function is the activation of the dioxygen moiety to serve as efficient catalysts for reactions of hydroxylation, desaturation or reduction. To date most studies on IMHME were carried out in metazoan, phototrophic or parasitic organisms, whereas genome-wide analysis in heterotrophic free living protozoa, such as the Ciliophora phylum, has not been undertaken. In the seven fully sequenced genomes available we retrieved 118 putative sequences of the IMHME type, albeit with large differences in number among the ciliates: 11 sequences in Euplotes octocarinatus, 7 in Ichthyophthirius multifiliis, 13 in Oxytricha trifallax, 18 in Stylonychia lemnae, 25 in Tetrahymena thermophila, 31 in Paramecium tetraurelia and 13 in Pseudocohnilembus persalinus.The pool of putative sequences was classified in 16 orthologous groups from which 11 were related to fatty acid desaturase (FAD) and 5 to the fatty acid hydroxylase (FAH) superfamilies. Noteworthy, a large diversity on the number and type of FAD / FAH proteins were found among the ciliates, a feature that, in principle, may be attributed to peculiarities of the evolutionary process, such as gene expansion and reduction, but also to horizontal gene transfer, as we demonstrate in this work. We identified twelve putative enzymatic activities, from which four were newly assigned activities: sphingolipid Δ4-desaturase, ω3/Δ15 fatty acid desaturase, a large group of alkane 1-monooxygenases, and acylamide-delta-3(E)-desaturase, although unequivocal allocation would require additional experiments. We also combined the phylogenetics analysis with lipids analysis, thereby allowing the detection of two enzymatic activities not previously reported: a C-5 sterol desaturase in P. tetraurelia and a delta-9 fatty acid desaturase in Cohnilembus reniformis.The analysis revealed a significant lower number of FAD’s sequences in the spirotrichea ciliates than in the oligohymenophorea, emphasizing the importance of fatty acids trophic transfer among aquatic organisms as a source of variation in metabolic activity, individual and population growth rates, and reproduction.

Highly concentrated palmitoleic acid proving the safety and efficacy of Provinal® for cardiometabolic disorders and dry eye syndrome

Palmitoleic acid (C16:1 n-7) or Omega-7 (O-7) is a monounsaturated fatty acid. It is biosynthesized from palmitic acid by the action of the delta-9 desaturase. It can also be obtained from sea buckthorn (Hippophae rhamnoides), macadamia nuts (Macadamia integrifolia) and marine sources (anchovies). The nutritional and biological functions of palmitoleic acid are complex and scientific understanding of the biological significance on human health is limited.

Overexpression of endogenous delta-6 fatty acid desaturase gene enhances eicosapentaenoic acid accumulation in Phaeodactylum tricornutum

Abstract The effect of overexpression of endogenous delta-6 fatty acid desaturase gene ( ER 6FAD ) on eicosapentaenoic acid (EPA) production and total lipid content was investigated in Phaeodactylum tricornutum . All three randomly selected transformants exhibited significant increase (47.66%) in their EPA content, which reached up to 38.101 mg/g DW in algal strain D63. The total lipid content of all the three transformants was significantly higher (16.40–18.64%) than that of the wild-type strain. These findings suggested that the reaction catalyzed by ER 6FAD is a limiting step for EPA biosynthesis, overexpression of endogenous ER 6FAD gene is an effective method for improving EPA production in eukaryotic microalgae, and fatty acid metabolic pathway in microalgae can be genetically modified.

Determination of Substrate Preferences for Desaturases and Elongases for Production of Docosahexaenoic Acid from Oleic Acid in Engineered Canola

Production of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in plant seed oils has been pursued to improve availability of these omega-3 fatty acids that provide important human health benefits. Canola (Brassica napus), through the introduction of 10 enzymes, can convert oleic acid (OLA) into EPA and ultimately DHA through a pathway consisting of two elongation and five desaturation steps. Herein we present an assessment of the substrate specificity of the seven desaturases and three elongases that were introduced into canola by expressing individual proteins in yeast. In vivo feeding experiments were conducted with 14 potential fatty acid intermediates in an OLA to DHA pathway to determine the fatty acid substrate profiles for each enzyme. Membrane fractions were prepared from yeast expression strains and shown to contain active enzymes. The elongases, as expected, extended acyl-CoA substrates in the presence of malonyl-CoA. To distinguish between enzymes that desaturate CoA- and phosphatidylcholine-linked fatty acid substrates, we developed a novel in vitro method. We show that a delta-12 desaturase from Phytophthora sojae, an omega-3 desaturase from Phytophthora infestans and a delta-4 desaturase from Thraustochytrium sp., all prefer phosphatidylcholine-linked acyl substrates with comparatively low use of acyl-CoA substrates. To further validate our method, a delta-9 desaturase from Saccharomyces cerevisiae was confirmed to use acyl-CoA as substrate, but could not use phosphatidylcholine-linked substrates. The results and the assay methods presented herein will be useful in efforts to improve modeling of fatty acid metabolism and production of EPA and DHA in plants.

Fatty acid compositions of plasma lipids in atopic dermatitis/asthma patients.

The proportions of linoleic acid in total plasma lipids and phospholipids were significantly greater and those of oleic acid were lower in pre-puberal and puberal atopic patients as compared with age-matched healthy controls. The n-3/n-6 fatty acid ratio of the triacylglycerol fraction was also lower in atopic patients. However, no significant decreases in the proportions of dihomo-gamma-linolenic acid and arachidonic acid were observed in plasma lipids of atopic patients, suggesting that delta 6-desaturase activity is not impaired in atopic patients. We provide an explanation for the beneficial effects of raising the n-3/n-6 ratio of dietary oils in the context of suppressing allergic hyper-reactivity in humans.

Docosapentaenoic Acid (22:5n-3) Downregulates mRNA Expression of Pro-inflammatory Factors in LPS-activated Murine Macrophage Like RAW264.7 Cells.

Docosapentaenoic acid (22:5n-3, n-3 DPA) is a n-3 polyunsaturated fatty acid (PUFA) found in fish oil, and has been reported to have health benefits. This study investigated conversion of n-3 DPA, and examined the anti-inflammatory effects of n-3 DPA on activated macrophages. Murine macrophage-like RAW264.7 cells were incubated in culture media containing n-3 DPA for 72 h. The level of n-3 DPA in the fatty acid composition of the total lipid fraction increased in a dose-dependent manner. Furthermore, the levels of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were higher in treated cells than in control cells. In RAW264.7 cells stimulated by lipopolysaccharide (LPS), n-3 DPA significantly down-regulated mRNA expression of pro-inflammatory factors such as IL-6, IL-1β, iNOS and COX-2. Production of IL-6 was also reduced by n-3 DPA in a dose-dependent manner. We found that n-3 DPA treatment resulted in greater IL-6 mRNA down-regulation than that achieved with EPA treatment, and was similar to that of DHA treatment. Furthermore, expression levels of IL-6 and IL-1β mRNAs were measured in the presence of the delta-6 desaturase inhibitor SC26196 in the culture medium to inhibit the conversion of n-3 DPA to DHA. There was no significant difference in the down-regulation in the mRNA expression of pro-inflammatory cytokines in RAW264.7 cells by n-3 DPA with or without presence of SC26196. These results demonstrate that n-3 DPA exhibits anti-inflammatory effects in activated RAW264.7 cells, which are independent of DHA conversion.

Diurnal variations in polyunsaturated fatty acid contents and expression of genes involved in their de novo synthesis in pigs

The daily variations in circulating fatty acid (FA) contents and lipid metabolism have been well documented. However, whether long chain polyunsaturated FA (PUFA) contents and expression of genes involved in their de novo synthesis exhibit daily rhythms are yet unknown. We conducted the present study to investigate the daily variations in PUFA contents in plasma and liver of pigs. Moreover, diurnal expression of genes encode fatty acid desaturases and elongases, which are key enzymes catalyzed de novo synthesis of long chain PUFA, were also explored. The results showed that long chain PUFA contents in plasma and liver both exhibited diurnal rhythms. Diurnal variations were also observed in mRNA expression of FASD1 (Delta 5-desaturase), FASD2 (Delta 6-desaturase), ELOVL5 (fatty acid elongase 5) and ELOVL2 in liver, with an unexpectedly high level at night. Moreover, our results showed a similarity between the diurnal patterns of FASD1, FASD2, ELOVL2, ELOVL5 and Period 2. These results indicated a high activity of the desaturase-elongase pathway at night in pigs. These findings have important physiological and pathophysiological implications, since long chain PUFA are essential for cell function and closely involved in the development of metabolic syndrome.

Lipid metabolites in seeds of diverse Gossypium accessions: molecular identification of a high oleic mutant allele.

Genetically diverse cottonseeds show altered compositions and spatial distributions of phosphatidylcholines and triacylglycerols. Lipidomics profiling led to the discovery of a novel FAD2 - 1 allele, fad2 - 1D - 1 , resulting in a high oleic phenotype. The domestication and breeding of cotton for elite, high-fiber cultivars have led to reduced variation of seed constituents within currently cultivated upland cotton genotypes. However, a recent screen of the genetically diverse U.S. National Cotton Germplasm Collection identified Gossypium accessions with marked differences in seed oil and protein content. Here, several of these accessions representing substantial variation in seed oil content were analyzed for quantitative and spatial differences in lipid compositions by mass spectrometric approaches. Results indicate considerable variation in amount and spatial distribution of pathway metabolites for triacylglycerol biosynthesis in embryos across Gossypium accessions, suggesting that this variation might be exploited by breeders for seed composition traits. By way of example, these lipid metabolite differences led to the identification of a mutant allele of the D-subgenome homolog of the delta-12 desaturase (fad2-1D-1) in a wild accession of G. barbadense that has a high oil and high oleic seed phenotype. This mutation is a 90-bp insertion in the 3' end of the FAD2-1D coding sequence and a modification of the 3' end of the gene beyond the coding sequence leading to the introduction of a premature stop codon. Given the large amounts of cottonseed produced around the world that is currently not processed into higher value products, these efforts might be one avenue to raise the overall value of the cotton crop for producers.

Overexpression of OLE1 Enhances Cytoplasmic Membrane Stability and Confers Resistance to Cadmium in Saccharomyces cerevisiae.

A S. cerevisiae gene encoding a delta-9 desaturase, OLE1, was associated with high anti-cadmium-stress activity. The data suggest that the regulation of OLE1 in the synthesis of unsaturated fatty acids may serve as a positive feedback mechanism to help yeast cells counter the lipid peroxidation and cytoplasmic membrane damage caused by cadmium. The discovery of OLE1 involvement in membrane stability may indicate a novel defense strategy against cadmium stress.

Dietary essential α-linolenic acid and linoleic acid differentially modulate TNFα-induced NFκB activity in FADS2-deficient HEK-293 cells

The pro- or anti-inflammatory bioactivity of dietary essential linoleic acid (LA) and alpha-linolenic acid (ALA) is mainly attributed to rate-limiting delta-6 desaturase (D6D) activity. The aim of this study was to analyze mechanisms of D6D-substrates ALA, LA and D6D-product gamma-linolenic acid (GLA) under D6D-deficient conditions. Fatty acid profiles (GC-MS), D6D gene expression (real-time RT-PCR) and NFκB activity (luciferase assay) were assessed in HEK293 cells. FADS2 gene expression was approved being marginal. Incubation with ALA or LA did not increase D6D products but their elongase products C20:3n-3 and C20:2n-6. Bypassing the D6D, GLA elevated C20:3n-6 and C20:4n-6. LA significantly increased (+18% at 60 μM; p < .001), ALA reduced (−32% at 100 μM; p < .001) and GLA did not specifically change NFκB activity. Our data indicate that D6D might not be essential for the distinct effects of LA and ALA on NFκB activity.

The sphingolipid biosynthetic enzyme Sphingolipid delta8 desaturase is important for chilling resistance of tomato.

The physiological functions of sphingolipids in animals have been intensively studied, while less attention has been paid to their roles in plants. Here, we reveal the involvement of sphingolipid delta8 desaturase (SlSLD) in the chilling resistance of tomato (Solanum lycopersicum cv. Micro-Tom). We used the virus-induced gene silencing (VIGS) approach to knock-down SlSLD expression in tomato leaves, and then evaluated chilling resistance. Changes in leaf cell structure under a chilling treatment were observed by transmission electron microscopy. In control plants, SlSLD was highly expressed in the fruit and leaves in response to a chilling treatment. The degree of chilling damage was greater in SlSLD-silenced plants than in control plants, indicating that SlSLD knock-down significantly reduced the chilling resistance of tomato. Compared with control plants, SlSLD-silenced plants showed higher relative electrolytic leakage and malondialdehyde content, and lower superoxide dismutase and peroxidase activities after a chilling treatment. Chilling severely damaged the chloroplasts in SlSLD-silenced plants, resulting in the disruption of chloroplast membranes, swelling of thylakoids, and reduced granal stacking. Together, these results show that SlSLD is crucial for chilling resistance in tomato.