Erythrocyte fatty acids and desaturase indices in early pregnancy are associated with risk of preeclampsia.

Preeclampsia (PE) is a pregnancy disorder that may be associated with inadequate maternal nutrition. Fatty acids are vital for placental and fetal growth. Fatty acid desaturases, key enzymes influencing the metabolism of polyunsaturated fatty acids, are reported to be associated with cardiometabolic risk. Any imbalance in the levels of omega-3 and omega-6 fatty acids can result in increased inflammatory response. The current study reports the levels of erythrocyte fatty acids and desaturase index across gestation in women who develop PE (n = 108) and compares them with non-PE women (n = 216). Maternal erythrocyte fatty acids were measured at 4 time points during pregnancy (i.e., 11-14, 18-22, 26-28 weeks and at delivery) using gas chromatography. Maternal total erythrocyte saturated fatty acids and omega-6/omega-3 fatty acid ratio was higher in the PE group as compared to the non-PE group at 11-14 weeks and 18-22 weeks respectively. Maternal Δ5 desaturase index was lower while Δ6 desaturase index was higher in the PE group at 11-14 and 18-22 weeks. Maternal stearoyl CoA desaturase-18 (SCD-18) index was lower at 11-14 weeks and at delivery. These changes were mainly observed in the early onset PE (EOP) group. Δ6 desaturase index at 11-14 weeks predicted the risk of EOP. Imbalance in fatty acid levels and desaturase indices predate the clinical diagnosis of PE, indicating their role in its pathophysiology. Measurement of fatty acids and desaturase indices in early pregnancy merits evaluation as predictors of risk of PE.

High-dose ferric citrate supplementation attenuates omega-3 polyunsaturated fatty acid biosynthesis via downregulating delta 5 and 6 desaturases in rats with high-fat diet-induced obesity.

Obesity is associated with an increased risk of an iron deficiency; however, a synergistic relationship between iron and lipid homeostasis was also observed. The aim of this study was to investigate the effects of pharmacological doses of iron supplementation on omega 3 (n-3) and omega 6 (n-6) polyunsaturated fatty acids (PUFAs). Sprague-Dawley (SD) rats were fed a normal diet or a 50% high-fat diet (HFD) without or with pharmacological doses of ferric citrate (0.25, 1, or 2 g ferric iron per kg diet) for 12 weeks, and erythrocyte profiles of n-3 and n-6 PUFAs were quantitated. Ferric citrate supplementation showed dose-related effects on liver inflammation, liver iron accumulation, and increasing circulating levels of iron, erythrocyte degradation biomarkers LVV-hemorphin-7, malondialdehyde (MDA), and insulin. Obese rats supplemented with 2 g ferric iron per kg diet also had decreased levels of eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and total n-3 PUFAs compared to rats fed a normal diet or HFD alone. A western blotting analysis revealed that iron-mediated downregulation of n-3 PUFA-converting enzymes (Δ5 and Δ6 desaturases) only occurred at high dosages (≥1 g ferric iron per kg diet). A Spearman correlation analysis showed that total liver iron and serum LVV-hemorphin-7 and MDA were negatively correlated with n-3 PUFAs and their converting enzymes (Δ5 and Δ6 desaturases) (all p < 0.05). In conclusion, obese rats that received high-dose ferric citrate supplementation (>1 g of ferric iron per kg diet) exhibited decreased n-3 PUFA levels via downregulation of expressions of Δ5 and Δ6 desaturase enzymes.

Dual expression of transgenic delta-5 and delta-6 desaturase in tilapia alters gut microbiota and enhances resistance to Vibrio vulnificus infection.

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), exhibit antibacterial and anti-inflammatory activities. Furthermore, diets rich in n-3 PUFAs are known to improve disease resistance and limit pathogen infection in commercial aquaculture fishes. In this study, we examined the effects of transgenic overexpression of n-3 PUFA biosynthesis genes on the physiological response to bacterial infection in tilapia. We first established tilapia strains with single or dual expression of salmon delta-5 desaturase and/or delta-6 desaturase and then challenged the fish with Vibrio vulnificus infection. Interestingly, our data suggest that n-3 PUFA-mediated alterations in gut microbiota may be important in determining disease outcome via effects on immune response of the host. Both liver- and muscle-specific single and dual expression of delta-5 desaturase and delta-6 desaturase resulted in higher n-3 PUFA content in transgenic fish fed with a LO basal diet. The enrichment of n-3 PUFAs in dual-transgenic fish is likely responsible for their improved survival rate and comparatively reduced expression of inflammation- and immune-associated genes after V. vulnificus infection. Gut microbiome analysis further revealed that dual-transgenic tilapia had high gut microbiota diversity, with low levels of inflammation-associated microbiota (i.e., Prevotellaceae). Thus, our findings indicate that dual expression of transgenic delta-5 and delta-6 desaturase in tilapia enhances disease resistance, an effect that is associated with increased levels of n-3 PUFAs and altered gut microbiota composition.

Intestinal delta-6-desaturase activity determines host range for Toxoplasma sexual reproduction.

Many eukaryotic microbes have complex life cycles that include both sexual and asexual phases with strict species specificity. Whereas the asexual cycle of the protistan parasite Toxoplasma gondii can occur in any warm-blooded mammal, the sexual cycle is restricted to the feline intestine. The molecular determinants that identify cats as the definitive host for T. gondii are unknown. Here, we defined the mechanism of species specificity for T. gondii sexual development and break the species barrier to allow the sexual cycle to occur in mice. We determined that T. gondii sexual development occurs when cultured feline intestinal epithelial cells are supplemented with linoleic acid. Felines are the only mammals that lack delta-6-desaturase activity in their intestines, which is required for linoleic acid metabolism, resulting in systemic excess of linoleic acid. We found that inhibition of murine delta-6-desaturase and supplementation of their diet with linoleic acid allowed T. gondii sexual development in mice. This mechanism of species specificity is the first defined for a parasite sexual cycle. This work highlights how host diet and metabolism shape coevolution with microbes. The key to unlocking the species boundaries for other eukaryotic microbes may also rely on the lipid composition of their environments as we see increasing evidence for the importance of host lipid metabolism during parasitic lifecycles. Pregnant women are advised against handling cat litter, as maternal infection with T. gondii can be transmitted to the fetus with potentially lethal outcomes. Knowing the molecular components that create a conducive environment for T. gondii sexual reproduction will allow for development of therapeutics that prevent shedding of T. gondii parasites. Finally, given the current reliance on companion animals to study T. gondii sexual development, this work will allow the T. gondii field to use of alternative models in future studies.

Dietary fish oil and flaxseed for rabbit does: fatty acids distribution and Δ6-desaturase enzyme expression of different tissues.

Standard feeds are imbalanced in term of n-6/n-3 polyunsaturated fatty acids (PUFA) ratio, with a low proportion of the latter. The reproductive system appears to be strongly affected by administration of n-3 PUFA, and ingredients rich in α-linolenic acid (ALA; i.e. vegetable sources) or EPA and DHA acids (i.e. fish oil) can be included in animal diets to balance PUFA intake. The aim of this study was to evaluate the effect of dietary supplementation with flaxseed (ALA) or fish oil (EPA and DHA) on PUFA metabolism in rabbit does. A total of 60 New Zealand White female rabbits were assigned to three experimental groups: control group, FLAX group fed 10% extruded flaxseed and FISH group fed 3% fish oil. Blood, milk, liver and ovaries were collected from the does to assess the lipid composition; furthermore, FADS2 gene expression was assessed in liver and ovary tissues. Reproductive performance of does was also recorded. The fertility rate and number of weaned rabbits improved with n-3 dietary supplementation: does at first parity showed the lowest reproductive results, but the administration of n-3 reduced the gap between primiparous and multiparous does. Feed consumption and milk production were not affected by the feeding regime. The fatty acid composition of milk, plasma, liver and ovaries were widely influenced by diet, showing higher concentrations of n-3 long-chain PUFA (LCP) in does fed with n-3 enriched diets. FISH diet resulted in the highest n-3 LCP enrichment, whereas in the FLAX group, this increase was lower. Blood and milk showed low levels of LCP, whereas liver and ovaries were the main sites of n-3 LCP synthesis and accumulation. Accordingly, although the liver is the main metabolic centre for LCP synthesis, ovaries also have a prominent role in LCP generation. FADS2 expression in liver and ovary tissue was downregulated by FISH administration. In conclusion, the enrichment of diets with n-3 PUFA could be an effective strategy for improving the reproductive performance of does.

Influence of dietary lipid levels on growth, nutrient utilization, tissue fatty acid composition and desaturase gene expression in silver barb (Puntius gonionotous) fingerlings.

Silver barb (Puntius gonionotus) is considered as a promising medium-sized carp species for freshwater aquaculture in Asia. This study in silver barb was carried out to evaluate the effects of increasing dietary levels of lipid on growth, nutrient utilization, whole-body composition, tissue fatty acid composition and Δ6 fatty acyl desaturase (Δ6 fad) gene expression. Fish (11.3 ±â€¯0.23 g of initial body weight) was fed for 60 days with five experimental diets: FO-0 (control feed); FO-30; FO-60; FO-90 and FO-120 containing 0, 30, 60, 90 and 120 g fish oil kg-1 diet, respectively. Among the diets, the highest specific growth rate (SGR), protein efficiency ratio (PER) and whole-body lipid content, and the lowest feed conversion ratio (FCR) were recorded with FO-120 diet. The saturated fatty acids (SFA) level in the muscle was significantly (P < .05) increased with the enhanced FO supplementation, whereas monounsaturated fatty acids (MUFA) level decreased. Increased level of fish oil in the diet also enhanced the n-3 PUFA and n-3 LC-PUFA (long-chain polyunsaturated fatty acid) in the muscle and liver. The expression of Δ6 fad gene was downregulated, whereas the serum biochemical constituents were either remain unchanged or enhanced with increased FO supplementation in the diets of silver barb.

F2-isoprostanes and fatty acids profile in early pregnancy complicated by pre-existing diabetes.

BACKGROUND: Diabetes and pregnancy are both associated with oxidative stress, characterized by an increase of F2-isoprostanes from the non-enzymatic oxidation of arachidonic acid, a n - 6 polyunsaturated fatty acid (PUFA). We hypothesized that pregnant women with pre-existing diabetes will be characterized by elevated levels of specific F2-isoPs isomers and altered PUFA composition in plasma early pregnancy when compared to normoglycemic controls. METHODS: Plasma samples from 23 women with uncomplicated pregnancies and 11 women with pre-existing diabetes in pregnancy were collected between 12 and 18 weeks of pregnancy (MIROS cohort). Six F2-isoprostanes isomers were measured by high-performance liquid chromatography coupled to tandem mass spectrometry. Fatty acids concentrations in plasmatic phospholipids were measured by gas chromatography coupled to a flame ionization detector. RESULTS: F2-isoprostanes, specifically the 8-iso-15(R)-PGF2α levels, were 67% higher in diabetic than normoglycemic pregnancies (p = 0.026). The total n - 6 PUFA and arachidonic acid level did not differ between study groups. In contrast, total n - 3 level was 32% lower in diabetic pregnancies than in controls (p = 0.002); EPA(20:5) and DHA(22:6) being specifically reduced (p = 0.035 and p = 0.003 respectively). Delta-6-desaturase (D6D) activity index, calculated using fatty acid ratios, was 9% lower in pre-existing diabetes than in controls (p = 0.042). CONCLUSIONS: Pre-existing diabetes in early pregnancy displays a distinctive F2-isoprostanes profile when compared to other pathologies of pregnancy, such as preeclampsia, as previously assessed in the same cohort.

Adding a purple corn extract in rats supplemented with chia oil decreases gene expression of SREBP-1c and retains Δ5 and Δ6 hepatic desaturase activity, unmodified the hepatic lipid profile.

Flavonoids upregulate gene expression of PPAR-α and underregulate the gene expression of SREBP-1c, and their intake increases the plasmatic concentration of n-3 LC-PUFAs. However, the biological mechanisms underlying these effects have not been elucidated. In this work, the effect of oral supplementation of ALA from chia (Salvia hispanica L.) seed oil and anthocyanins from a purple corn extract (PCE) on gene expression of SREBP-1c, PPAR-α and Δ5 and Δ6 desaturases (Δ5D and Δ6D), the activity of these enzymes in the liver as well as the hepatic lipid profile were evaluated in thirty-six female Sprague Dawley rats whose diet was supplemented with olive oil (OL), chia oil (CH), olive oil and PCE (OL + PCE) or chia oil and PCE (CH + PCE). Gene expression of PPAR-α was significantly higher when supplemented with CH and CH + PCE, SREBP-1c gene expression was higher when supplemented with chia oil. CH supplementation enhanced Δ5D expression whereas no significant differences between treatments were observed concerning Δ6D gene expression. Activities of both desaturases were increased by including olive oil (OL + PCE and OL), and they were found to be higher in CH + PCE respect to CH for both enzymes. The ALA and n-3 LCPUFAs hepatic content was higher with CH, decreasing the levels of AA and n-6 LCPUFAs. It is concluded that the joint action of flavonoids such as anthocyanins and ALA show an anti-adipogenic effect. Desaturase activity was inhibited by ALA and kept by the anthocyanins from PCE, thus anthocyanins would exert a protective effect on the desaturase activity but they would not affect on its gene expression, however, high doses of ALA increased the production of its metabolites, masking the effect of PCE.

Hepatic Lipogenesis and Brain Fatty Acid Profile in Response to Different Dietary n6/n3 Ratios and DHA/EPA Supplementation in Streptozotocin Treated Rats.

SCOPE: We investigated the interaction between streptozotocin (STZ)-induced diabetes and dietary n6/n3 ratio, and its influence on lipogenesis. METHODS AND RESULTS: The animals were treated with STZ and fed with different dietary n6/n3 ratios: 1, 7, and 60, or supplemented with DHA/EPA. Gene expression was assessed by RT-PCR and protein expression by western blotting and immunohistochemistry. Fatty acid profile was determined by GC-MS. Pancreas and liver histology were assessed by hematoxylin and eosin (H&E) staining. STZ-induced characteristic changes in all STZ treated groups, including: increased blood glucose, decreased body mass, increased lipid peroxidation and CD36 expression, decreased 16:1n7 and 18:1n7, increases in 20:3n6, decreases in phospholipid (PL) content of 20:4n6, as well as decreases in the expression of SREBP1c, Δ-9-desaturase (Δ9D), and Δ-5-desaturase (Δ5D). Additionally, other changes occurred that were dependent on the n6/n3 ratio. Among the diabetic groups, the lower n6/n3 ratio caused higher lipid peroxidation and CD36 expression, a greater decrease in 20:4n6 and decreased Δ6-desaturase (Δ6D) expression, while the higher n6/n3 ratio caused increased partitioning of 20:4n6 into hepatic neutral lipids (NL), a decrease in 20:5n3 content, and increased ß-oxidation. CONCLUSION: Presented data suggest that the n6/n3 ratio could significantly influence lipogenesis, lipid peroxidation, and ß-oxidation in STZ-induced diabetes, which could have clinical significance.

Production of eicosapentaenoic acid by application of a delta-6 desaturase with the highest ALA catalytic activity in algae.

Dunaliella salina is a unicellular green alga with a high α-linolenic acid (ALA) level, but a low eicosapentaenoic acid (EPA) level. In a previous analysis of the catalytic activity of delta 6 fatty acid desaturase (FADS6) from various species, FADS6 from Thalassiosira pseudonana (TpFADS6), a marine diatom, showed the highest catalytic activity for ALA. In this study, to enhance EPA production in D. salina, FADS6 from D. salina (DsFADS6) was identified, and substrate specificities for DsFADS6 and TpFADS6 were characterized. Furthermore, a plasmid harboring the TpFADS6 gene was constructed and overexpressed in D. salina. Our results revealed that EPA production reached 21.3 ± 1.5 mg/L in D. salina transformants. To further increase EPA production, myoinositol (MI) was used as a growth-promoting agent; it increased the dry cell weight of D. salina transformants, and EPA production reached 91.3 ± 11.6 mg/L. The combination of 12% CO2 aeration with glucose/KNO3 in the medium improved EPA production to 192.9 ± 25.7 mg/L in the Ds-TpFADS6 transformant. We confirmed that the increase in ALA was optimal at 8 °C; the EPA percentage reached 41.12 ± 4.78%. The EPA yield was further increased to 554.3 ± 95.6 mg/L by supplementation with 4 g/L perilla seed meal (PeSM), 500 mg/L MI, and 12% CO2 aeration with glucose/KNO3 at varying temperatures. EPA production and the percentage of EPA in D. salina were 343.8-fold and 25-fold higher than those in wild-type D. salina, respectively. IMPORTANCE: FADS6 from Thalassiosira pseudonana, which demonstrates high catalytic activity toward α-linolenic acid, was used to enhance EPA production by Dunaliella salina. Transformation of FADS6 from Thalassiosira pseudonana into Dunaliella salina with myoinositol, CO2, low temperatures, and perilla seed meal supplementation substantially increased EPA production in Dunaliella salina to 554.3 ± 95.6 mg/L. Accordingly, D. salina could be a potential alternative source of EPA and is suitable for its large-scale production.

Iron-induced pro-oxidant and pro-lipogenic responses in relation to impaired synthesis and accretion of long-chain polyunsaturated fatty acids in rat hepatic and extrahepatic tissues.

OBJECTIVES: Iron is involved in processes involving oxygen transfer and utilization. Excess iron is linked to cardiovascular diseases and some types of cancer. Iron overload is associated with oxidative stress development, and may have important interactions with lipid metabolism in the liver favoring the development and progression of non-alcoholic fatty liver disease. The aim of the study described here was to assess the effect of high intake of iron on oxidative stress-related parameters, lipid metabolism, and levels of long-chain polyunsaturated fatty acids (LCPUFAs) in liver and other tissues of the rat. METHODS: Male Wistar rats (21 d old) were fed an iron-rich diet (200 mg iron/kg diet, IRD) versus a control diet (50 mg iron/kg diet; CD) for 21 d. Samples of erythrocytes, liver, adipose tissue, brain, heart, and testicles were evaluated for fatty acid composition and hepatic biochemical and oxidative stress parameters, Δ-6 and Δ-5 desaturase activities, SREBP-1c and PPAR-α mRNA expression and DNA-binding capacity, and lipolytic, lipogenic, and antioxidant enzymatic activities. RESULTS: The IRD caused liver steatosis and increased activity of plasma transaminases, with higher oxidative stress status in plasma and liver. Liver Δ-6 and Δ-5 desaturase exhibited decreased activity, but enhanced expression in response to the IRD compared with the CD, with lower levels of ω-3 and ω-6 LCPUFAs and higher expression and DNA binding of SREBP-1c, whereas expression and DNA-binding activity of PPAR-α were diminished. CONCLUSIONS: IRD induced oxidative stress and a reduction in the desaturation capacity of the liver, with LCPUFA depletion in the different tissues studied, thus promoting a pro-steatotic condition in the liver.

Influence of water salinity on genes implicated in somatic growth, lipid metabolism and food intake in Pejerrey (Odontesthes bonariensis).

Pejerrey, Odontesthes bonariensis, is an euryhaline fish of commercial importance in Argentina. This work aimed to determine if water salinity affects the expression of genes involved in somatic growth (gh; ghr-I; ghr-II; igf-I), lipid metabolism (Δ6-desaturase) and food intake (nucb2/nesfatin-1). First, we identified the full-length cDNA sequences of Δ6-desaturase (involved in lipid metabolism) and nesfatin-1 (an anorexigen). Then, pejerrey juveniles were reared during 8weeks in three different water salinity conditions: 2.5g/L (S2.5), 15g/L (S15) and 30g/L (S30) of NaCl. Brain, pituitary, liver and muscle samples were collected in order to analyze mRNA expression. The expression of gh and ghr-II mRNAs increased in the pituitary of fish reared at S2.5 and S30 compared with the S15 group. The expression of ghr-I was higher in the liver of S30 group compared to S2.5 and S15. Igf-I mRNA expression in liver increased with the increment of water salinity, while it decreased in the muscle of S15 and S30 groups. Δ6-desaturase expression increased in S2.5 group compared to S15 in both liver and muscle. S30 caused a decrease in the Δ6-desaturase expression in liver compared to S15. The S30 treatment produced an increase in nucb2/nesfatin-1 mRNA expression in the brain and liver compared to S2.5 and S15. The changes in gene expression observed could help pejerrey perform better during salinity challenges. The S30 condition would likely promote pejerrey somatic growth in the long term.

Hydroxytyrosol prevents reduction in liver activity of Δ-5 and Δ-6 desaturases, oxidative stress, and depletion in long chain polyunsaturated fatty acid content in different tissues of high-fat diet fed mice.

BACKGROUND: Eicosapentaenoic acid (EPA, C20:5n-3), docosahexaenoic acid (DHA, C22:6n-3) and arachidonic acid (AA, C20:4n-6) are long-chain polyunsaturated fatty acids (LCPUFAs) with relevant roles in the organism. EPA and DHA are synthesized from the precursor alpha-linolenic acid (ALA, C18:3n-3), whereas AA is produced from linoleic acid (LA, C18:2n-6) through the action of Δ5 and Δ6-desaturases. High-fat diet (HFD) decreases the activity of both desaturases and LCPUFA accretion in liver and other tissues. Hydroxytyrosol (HT), a natural antioxidant, has an important cytoprotective effects in different cells and tissues. METHODS: Male mice C57BL/6 J were fed a control diet (CD) (10% fat, 20% protein, 70% carbohydrates) or a HFD (60% fat, 20% protein, 20% carbohydrates) for 12 weeks. Animals were daily supplemented with saline (CD) or 5 mg HT (HFD), and blood and the studied tissues were analyzed after the HT intervention. Parameters studied included liver histology (optical microscopy), activity of hepatic desaturases 5 and 6 (gas-liquid chromatography of methyl esters derivatives) and antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase by spectrophotometry), oxidative stress indicators (glutathione, thiobarbituric acid reactants, and the antioxidant capacity of plasma), gene expression assays for sterol regulatory element-binding protein 1c (SREBP-1c) (qPCR and ELISA), and LCPUFA profiles in liver, erythrocyte, brain, heart, and testicle (gas-liquid chromatography). RESULTS: HFD led to insulin resistance and liver steatosis associated with SREBP-1c upregulation, with enhancement in plasma and liver oxidative stress status and diminution in the synthesis and storage of n-6 and n-3 LCPUFAs in the studied tissues, compared to animals given control diet. HT supplementation significantly reduced fat accumulation in liver and plasma as well as tissue metabolic alterations induced by HFD. Furthermore, a normalization of desaturase activities, oxidative stress-related parameters, and tissue n-3 LCPUFA content was observed in HT-treated rats over control animals. CONCLUSIONS: HT supplementation prevents metabolic alterations in desaturase activities, oxidative stress status, and n-3 LCPUFA content in the liver and extrahepatic tissues of mice fed HFD.

Application of a delta-6 desaturase with α-linolenic acid preference on eicosapentaenoic acid production in Mortierella alpina.

BACKGROUND: Delta-6 desaturase (FADS6) is a key bifunctional enzyme desaturating linoleic acid (LA) or α-linolenic acid (ALA) in the biosynthesis of polyunsaturated fatty acids (PUFAs). In previous work, we analyzed the substrate specificity of two FADS6 enzymes from Mortierella alpina ATCC 32222 (MaFADS6) and Micromonas pusilla CCMP1545 (MpFADS6), which showed preference for LA and ALA, respectively. We also clarified the PUFA profiles in M. alpina, where these lipids were synthesized mainly via the ω6 pathway and rarely via the ω3 pathway and as a result contained low ALA and eicosapentaenoic acid (EPA) levels. RESULT: To enhance EPA production in M. alpina by favoring the ω3 pathway, a plasmid harboring the MpFADS6 gene was constructed and overexpressed in a uracil-auxotrophic strain of M. alpina using the Agrobacterium tumefaciens-mediated transformation (ATMT) method. Our results revealed that the EPA production reached 80.0 ± 15.0 and 90.4 ± 9.7 mg/L in MpFADS6 transformants grown at 28 and at 12 °C, respectively. To raise the level of ALA, free form fatty acid was used as exogenous substrate, which increased the EPA production up to 114.5 ± 12.4 mg/L. To reduce the cost of EPA production in M. alpina, peony seed oil (PSO) and peony seed meal (PSM) were used as source of ALA, and EPA production was improved to 149.3 ± 7.8 and 515.29 ± 32.66 mg/L by supplementing with 0.1 % PSO and 50 g/L PSM, respectively. The EPA yield was further increased to 588.5 ± 29.6 mg/L in a 5-L bioreactor, which resulted in a 26.2-fold increase compared to EPA production in wild-type M. alpina. In this work, we have significantly enhanced EPA production through overexpression of a FADS6 desaturase with preference for ALA, combined with supplementation of its substrate. CONCLUSION: An ALA-preferring FADS6 from M. pusilla CCMP1545 was applied to enhance EPA production in M. alpina. By exogenous addition of peony seed oil or peony seed meal, EPA production was further increased in flasks and fermenters. This research also highlights the value of peony seed meal which can be converted to a high value-added product containing EPA, and as a way to increase the EPA/AA ratio in M. alpina.

A fatty acyl desaturase (fads2) with dual Δ6 and Δ5 activities from the freshwater carnivorous striped snakehead Channa striata.

There is a lack of understanding on how the environment and trophic niche affect the capability of long-chain polyunsaturated fatty acids (LC-PUFA) in freshwater carnivorous teleost. In this present study, we isolated and functionally characterised a fatty acyl desaturase (Fads) from the striped snakehead Channa striata. Sequence comparison and phylogenetic analysis suggested a Fads2 protein that is closely related to previously characterised Fads2 proteins from freshwater carnivorous and marine herbivorous fish species. We further demonstrated the capacity of Δ6 and Δ5 desaturation activities for this particular desaturase, with highest activities towards the conversion of omega-3 (n-3) polyunsaturated fatty acids (PUFA). Low Δ4 desaturation activity was also detected, although the significance of this at a physiological level remains to be studied. The expression of this striped snakehead Δ6/Δ5 fads2 gene was highest in brain, followed by liver and intestine. In liver, diet fortified with high LC-PUFA concentration impeded the expression of Δ6/Δ5 fads2 gene compared to vegetable oil (VO) based diets. The discovery of Δ6/Δ5 Fads2 desaturase here complements the previous discovery of a Δ4 Fads2 desaturase and an Elovl5 elongase, lending proof to the existence of all the required enzymatic machinery to biosynthesise LC-PUFA from C18 PUFA in a freshwater carnivorous species.

Vegetable oils rich in alpha linolenic acid increment hepatic n-3 LCPUFA, modulating the fatty acid metabolism and antioxidant response in rats.

Alpha-linolenic acid (C18:3 n-3, ALA) is an essential fatty acid and the metabolic precursor of long-chain polyunsaturated fatty acids (LCPUFA) from the n-3 family with relevant physiological and metabolic roles: eicosapentaenoic acid (C20:5 n-3, EPA) and docosahexaenoic acid (C22:6 n-3, DHA). Western diet lacks of suitable intake of n-3 LCPUFA and there are recommendations to increase the dietary supply of such nutrients. Seed oils rich in ALA such as those from rosa mosqueta (Rosa rubiginosa), sacha inchi (Plukenetia volubis) and chia (Salvia hispanica) may constitute an alternative that merits research. This study evaluated hepatic and epididymal accretion and biosynthesis of n-3 LCPUFA, the activity and expression of Δ-5 and Δ-6 desaturase enzymes, the expression and DNA-binding activity of PPAR-α and SREBP-1c, oxidative stress parameters and the activity of antioxidative enzymes in rats fed sunflower oil (SFO, 1% ALA) as control group, canola oil (CO, 10% ALA), rosa mosqueta oil (RMO, 33% ALA), sacha inchi oil (SIO, 49% ALA) and chia oil (ChO, 64% ALA) as single lipid source. A larger supply of ALA increased the accretion of n-3 LCPUFA, the activity and expression of desaturases, the antioxidative status, the expression and DNA-binding of PPAR-α, the oxidation of fatty acids and the activity of antioxidant enzymes, whereas the expression and DNA-binding activity of SREBP-1c transcription factor and the biosynthetic activity of fatty acids declined. Results showed that oils rich in ALA such as SIO and ChO may trigger metabolic responses in rats such as those produced by n-3 PUFA.

Red Blood Cell Fatty Acids and Incident Diabetes Mellitus in the Women's Health Initiative Memory Study.

CONTEXT: The relations between dietary and/or circulating levels of fatty acids and the development of type 2 diabetes is unclear. Protective associations with the marine omega-3 fatty acids and linoleic acid, and with a marker of fatty acid desaturase activity delta-5 desaturase (D5D ratio) have been reported, as have adverse relations with saturated fatty acids and D6D ratio. OBJECTIVE: To determine the associations between red blood cell (RBC) fatty acid distributions and incident type 2 diabetes. DESIGN: Prospective observational cohort study nested in the Women's Health Initiative Memory Study. SETTING: General population. SUBJECTS: Postmenopausal women. MAIN OUTCOME MEASURES: Self-reported incident type 2 diabetes. RESULTS: There were 703 new cases of type 2 diabetes over 11 years of follow up among 6379 postmenopausal women. In the fully adjusted models, baseline RBC D5D ratio was inversely associated with incident type 2 diabetes [Hazard Ratio (HR) 0.88, 95% confidence interval (CI) 0.81-0.95) per 1 SD increase. Similarly, baseline RBC D6D ratio and palmitic acid were directly associated with incident type 2 diabetes (HR 1.14, 95% CI 1.04-1.25; and HR 1.24, 95% CI 1.14-1.35, respectively). None of these relations were materially altered by excluding incident cases in the first two years of follow-up. There were no significant relations with eicosapentaenoic, docosahexaenoic or linoleic acids. CONCLUSIONS: Whether altered fatty acid desaturase activities or palmitic acid levels are causally related to the development of type 2 diabetes cannot be determined from this study, but our findings suggest that proportions of certain fatty acids in RBC membranes are associated with risk for type 2 diabetes.

Cloning and functional characterization of Δ6 fatty acid desaturase (FADS2) in Eurasian perch (Perca fluviatilis).

The Eurasian perch (Perca fluviatilis) is a freshwater carnivorous species of high interest to diversify inland aquaculture. However, little is known about its ability to bioconvert polyunsaturated fatty acids (PUFAs) from plant oils into long chain polyunsaturated fatty acids (LC-PUFAs). In this study, special attention has been given to the fatty acid desaturase 2 (FADS2) which is commonly described to be a rate-limiting enzyme of the LC-PUFA biosynthesis. This work reports on the cloning, tissue expression and functional characterization of the Eurasian perch fads2, but also on the cloning of two alternative splicing transcripts named fads2-AS1 and fads2-AS2. The fads2 cDNA cloned is composed of an open reading frame (ORF) of 1338 nucleotides (nt) and encodes a protein of 445 amino acids. This deduced amino acid sequence displays the typical structure of microsomal FADS2 including two transmembrane domains and an N-terminal cytochrome b5 domain with the "HPGG" motif. Quantitative real-time PCR assay of fads2, fads2-AS1 and fads2-AS2 expressions revealed that the fads2 transcript was mainly expressed in the liver and intestine and exhibited a typical gene expression pattern of freshwater species while fads2-AS1 and fads2-AS2 genes were highly expressed in the brain, followed by the liver and intestine. Functional characterization of Eurasian perch FADS2 in transgenic yeast showed a fully functional Δ6 desaturation activity toward C18 PUFA substrates, without residual Δ5 and Δ8 desaturase activities.

Δ6-fatty acid desaturase and fatty acid elongase mRNA expression, phagocytic activity and weight-to-length relationships in channel catfish (Ictalurus punctatus) fed alternative diets with soy oil and a probiotic.

A time-course feeding trial was conducted for 120 days on juvenile channel catfish (Ictalurus punctatus) to study the effects of diets differing in oil source (fish oil or soy oil) and supplementation with a commercial probiotic. Relative levels of Δ6-fatty acid desaturase (Δ6-FAD) and fatty acid elongase (FAE) expression were assessed in brain and liver tissues. Both genes showed similar expression levels in all groups studied. Fish weight-to-length relationships were evaluated using polynomial regression analyses, which identified a burst in weight and length in the channel catfish on day 105 of treatment; this increase was related to an increase in gene expression. Mid-intestinal lactic acid bacterium (LAB) count was determined according to morphological and biochemical criteria using API strips. There was no indication that intestinal LAB count was affected by the modified diets. The Cunningham glass adherence method was applied to evaluate phagocytic cell activity in peripheral blood. Reactive oxygen species (ROS) generation was assessed through the respiratory burst activity of spleen macrophages by the NBT reduction test. Probiotic-supplemented diets provided a good substrate for innate immune system function; the phagocytic index was significantly enhanced in fish fed soy oil and the probiotic, and at the end of the experimental period, ROS production increased in fish fed soy oil. The substitution of fish oil by soy oil is recommended for food formulation and will contribute to promoting sustainable aquaculture. Probiotics are also recommended for channel catfish farming as they may act as immunonutrients.

Intrauterine programming of lipid metabolic alterations in the heart of the offspring of diabetic rats is prevented by maternal diets enriched in olive oil.

SCOPE: Maternal diabetes can program metabolic and cardiovascular diseases in the offspring. The aim of this work was to address whether an olive oil supplemented diet during pregnancy can prevent lipid metabolic alterations in the heart of the offspring of mild diabetic rats. METHODS AND RESULTS: Control and diabetic Wistar rats were fed during pregnancy with either a standard diet or a 6% olive oil supplemented diet. The heart of adult offspring from diabetic rats showed increases in lipid concentrations (triglycerides in males and phospholipids, cholesterol, and free fatty acids in females), which were prevented with the maternal diets enriched in olive oil. Maternal olive oil supplementation increased the content of unsaturated fatty acids in the hearts of both female and male offspring from diabetic rats (possibly due to a reduction in lipoperoxidation), increased the expression of Δ6 desaturase in the heart of male offspring from diabetic rats, and increased the expression of peroxisome proliferator activated receptor α in the hearts of both female and male offspring from diabetic rats. CONCLUSION: Relevant alterations in cardiac lipid metabolism were evident in the adult offspring of a mild diabetic rat model, and regulated by maternal diets enriched in olive oil.