Proportions Of EPA Research Articles

Reconstruction of Long-Chain Polyunsaturated Acid Synthesis Pathways in Marine Red Microalga Porphyridium cruentum Using Lipidomics and Transcriptomics.

The marine red microalga Porphyridium can simultaneously synthesize long-chain polyunsaturated fatty acids, including eicosapentaenoic acid (C20:5, EPA) and arachidonic acid (C20:4, ARA). However, the distribution and synthesis pathways of EPA and ARA in Porphyridium are not clearly understood. In this study, Porphyridium cruentum CCALA 415 was cultured in nitrogen-replete and nitrogen-limited conditions. Fatty acid content determination, transcriptomic, and lipidomic analyses were used to investigate the synthesis of ARA and EPA. The results show that membrane lipids were the main components of lipids, while storage lipids were present in a small proportion in CCALA 415. Nitrogen limitation enhanced the synthesis of storage lipids and ω6 fatty acids while inhibiting the synthesis of membrane lipids and ω3 fatty acids. A total of 217 glycerolipid molecular species were identified, and the most abundant species included monogalactosyldiglyceride (C16:0/C20:5) (MGDG) and phosphatidylcholine (C16:0/C20:4) (PC). ARA was mainly distributed in PC, and EPA was mainly distributed in MGDG. Among all the fatty acid desaturases (FADs), the expressions of Δ5FAD, Δ6FAD, Δ9FAD, and Δ12FAD were up-regulated, whereas those of Δ15FAD and Δ17FAD were down-regulated. Based on these results, only a small proportion of EPA was synthesized through the ω3 pathway, while the majority of EPA was synthesized through the ω6 pathway. ARA synthesized in the ER was likely shuttled into the chloroplast by DAG and was converted into EPA by Δ17FAD.

Analysis of fatty acid composition and sensitivity to dietary n-3 PUFA intervention of mouse n-3 PUFA-enriched tissues/organs

Purposen-3 polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (DHA; C22:6 n3) and eicosapentaenoic acid (EPA; C20:5 n3), are of concern for their health-promoting effects such as anti-inflammatory, but the tissue selectivity for n-3 PUFA (i.e., which tissues and organs are rich in n-3 PUFA) is still not well known. In addition, it is unclear which tissues and organs are more sensitive to n-3 PUFA intervention. These unresolved issues have greatly hindered the exploring of the health benefits of n-3 PUFA. MethodsTwenty-four 7-week-old male C57BL/6 J mice were assigned to the control, fish oil, DHA, and EPA groups. The last three groups were given a 4-week oral intervention of fatty acids in ethyl ester (400 mg/kg bw). The fatty acid profiles in 27 compartments were determined by gas chromatography. ResultsThe proportion of long-chain n-3 PUFA (the total relative percentage of EPA, DPA n3, and DHA) was analyzed. Eight tissues and organs, including the brain (cerebral cortex, hippocampus, hypothalamus) and peripheral organs (tongue, quadriceps, gastrocnemius, kidney, and heart) were determined as being n-3 PUFA-enriched tissues and organs, owing to their high n-3 PUFA levels. The highest n-3 PUFA content was observed in the tongue for the first time. Notably, the content of linoleic acid (LA; C18:2 n6c) in peripheral organs was observed to be relatively high compared with that in the brain. Interestingly, the proportions of EPA in the kidney, heart, quadriceps, gastrocnemius, and tongue increased more markedly after the EPA intervention than after the DHA or fish oil intervention. As expected, the levels of proinflammatory arachidonic acid (AA; C20:4 n6) in the kidney, quadriceps, and tongue were markedly decreased after the three dietary interventions. ConclusionPeripheral tissues and organs, including the tongue, quadriceps, gastrocnemius, kidney, and heart, besides the brain, showed obvious tissue selectivity for n-3 PUFA. In the whole body of mice, the tongue exhibits the strongest preference for n-3 PUFA, with the highest proportion of n-3 PUFA. Moreover, these peripheral tissues and organs, especially the kidney, are more sensitive to dietary EPA administration in comparison with the brain.

Combined application of exogenous phytohormones and blue light illumination to the marine diatom Phaeodactylum tricornutum

Diatoms constitute a diverse group of photosynthetic microorganisms with great potential for biotechnological applications. Compounds which they can synthesise, such as ω3-fatty acids or carotenoid pigments, can find uses in the pharmacology, nutraceutical or cosmetic sectors. However, a major challenge to date has been to stimulate the synthesis of valuable metabolites without hampering cell growth.In this study, the model microalgal species Phaeodactylum tricornutum (marine diatom) was subjected to blue light illumination and phytohormonal supplementation (gibberellic acid, GA3, and abscisic acid, ABA) as single factors or in combination. P. tricornutum was grown under a batch culture regime for 30 days and treatments were tested at two different stages (day 0 and day 20).The highest yield of dry biomass was obtained when combining blue light and GA3 from day 0 (25 % higher than control) while no relevant variation occurred when applying blue light from day 20. When applied from day 0, blue light led to a reduction in the fucoxanthin and PUFA content of the biomass. Single dose supplementations of the phytohormones seemed less dependent on the time of application. When applied without blue light, GA3 (2 mg/l) increased the fucoxanthin content and yield by 25 and 30 %, respectively. However, the co-supplementation of GA3 and ABA (2 mg/l) was more effective than single applications, significantly boosting fucoxanthin yield up to 1.3 mg/l and EPA proportions by 17 %, compared to the control set. These increments were also associated with enhanced antioxidant activity (60 % increment).These results highlight the importance of optimising the timing of application of treatments to avoid deleterious effects on pigment and PUFA accumulation in cells. Switching to blue light illumination and applying GA3 and ABA later in the growth of the diatom P. tricornutum constitutes a promising strategy to improve its yields in high-value metabolites prior to biomass harvest.

Cold stress combined with salt or abscisic acid supplementation enhances lipogenesis and carotenogenesis in Phaeodactylum tricornutum (Bacillariophyceae).

Compounds from microalgae such as ω3-fatty acids or carotenoid are commercially exploited within the pharmacology, nutraceutical, or cosmetic sectors. The co-stimulation of several compounds of interest may improve the cost-effectiveness of microalgal biorefinery pipelines. This study focussed on Phaeodactylum tricornutum to investigate the effects on lipogenesis and carotenogenesis of combined stressors, here cold temperature and addition of NaCl salt or the phytohormone abscisic acid, using a two-stage cultivation strategy. Cold stress with NaCl or phytohormone addition increased the neutral lipid content of the biomass (20 to 35%). These treatments also enhanced the proportions of EPA (22% greater than control) in the fatty acid profile. Also, these treatments had a stimulatory effect on carotenogenesis, especially the combination of cold stress with NaCl addition, which returned the highest production of fucoxanthin (33% increase). The gene expression of diacylglycerol acyltransferase (DGAT) and the ω-3 desaturase precursor (PTD15) were enhanced 4- and 16-fold relative to the control, respectively. In addition, zeaxanthin epoxidase 3 (ZEP3), was downregulated at low temperature when combined with abscisic acid. These results highlight the benefits of applying a combination of low temperature and salinity stress, to simultaneously enhance the yields of the valuable metabolites EPA and fucoxanthin in Phaeodactylum tricornutum.

Erythrocyte fatty acid membrane composition in children on long-term parenteral nutrition enriched with ω-3 fatty acids

Composite lipid emulsions containing soybean oil (30%), medium-chain triglycerides (30%), olive oil (25%), and fish oil (15%) (SMOF) are now widely used. We aimed to evaluate the tolerance, the efficiency, and the erythrocyte fatty acid (FA) profile for children on long-term home parenteral nutrition (HPN) receiving a composite fish oil-based emulsion (FOLE). At baseline, children (n=46) with severe intestinal failure highly dependent on parenteral nutrition (PN) for ≥1 y were included in the study when they had received the composite FOLE for >6 mo. Out of this baseline group, only 25 children remained highly PN-dependent (SMOF1, n=25) and could be assessed a second time, 2.4 y later (SMOF2, n=25). An independent control group ("weaned off PN" group; n=24) included children who had been weaned off PN for >2 y (median: 4 y). RBC-FA composition was established by GC-MS. Growth parameters, plasma citrulline, conjugated bilirubin, FA profiles, and the Holman ratio (20:3ω-9/20:4ω-6) were compared between groups. No difference for growth parameters, citrulline, and bilirubin was observed between the SMOF groups after 2.4 y (0.2<P<0.8). The weaned-off group did not differ from the SMOF groups for growth parameters (0.2<P<0.4) but citrulline was higher (P<0.0001) and conjugated bilirubin lower (P<0.01). The composite FOLE induced higher proportions of EPA (20:5n-3) (8.4%±2.9%) and DHA (22:6n-3) (11.7%±2.2%) than what was observed in weaned-off children (0.8%±0.4% and 6.6%±2.3%, respectively) but lower proportions of arachidonic acid (20:4n-6). However, the Holman ratio did not vary between groups (P=0.9), whereas the PUFA concentrations varied widely. Long-term use of the composite FOLE was well tolerated in HPN-dependent children. The RBC-FA profile alterations were consistent with the ω-3 PUFA-enriched composition of this emulsion without evidence of essential FA deficiency.

Turning Waste into A Resource: Isolation and Characterization of High-Quality Collagen and Oils from Atlantic Bluefin Tuna Discards

At the behest of the Green Deal, circular economy concepts are currently being widely promoted, not least within the aquaculture sector. The current study aims to demonstrate the technical feasibility of extracting collagen and fish oils from waste Atlantic bluefin tuna biomass originating from the Maltese aquaculture industry. For collagen, a three-stage methodology, consisting of pre-treatment, extraction, and retrieval, was applied to biomass originating from bone, skin, muscle, and internal organs (offal) in order to extract both acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC). The chemical identity of the extracted collagen was confirmed through the conduction of hydroxyproline and SDS-PAGE tests as well as through FTIR, whilst the extracted collagen was also tested for its microbiological and heavy metal profiles. The collagen yield was found to be highest for skin tissue and for PSC-based protocols and is comparable to the yield cited in the literature for other tuna species. Oils were extracted through low temperature, high temperature, and enzymatic means. The fatty acid profile of the extracted oils was assessed using GC-FID; this indicated high proportions of EPA and DHA. Yield indicated that the enzymatic extraction of oil is most effective. High heat and the presence of iron-containing muscle starting material promote oxidation and rancidity. Further effort into the optimization of both collagen and lipid extraction protocols must be invested, with a special focus on the production of high-value fractions that are much closer to the quality required for human use/consumption.

Comparative Response of Marine Microalgae to H2O2-Induced Oxidative Stress.

There have been growing interests in the biorefining of bioactive compounds from marine microalgae, including pigments, omega-3 fatty acids or antioxidants for use in the nutraceutical and cosmetic sectors. This study focused on the comparative responses of five marine microalgal species from different lineages, including the dinoflagellate Amphidinium carterae, chlorophyte Brachiomonas submarina, diatom Stauroneis sp., haptophyte Diacronema sp. and rhodophyte Rhodella violacea, to exposure during their batch growth to hydrogen peroxide (H2O2). A. carterae returned an enhanced signal with the DPPH assay (8.8µmol Trolox eq/g DW) when exposed to H2O2, which was associated with reduced pigment yields and increased proportions in saturated C16 and C18 fatty acids. B. submarina showed enhanced antioxidant response upon exposure to H2O2 with the DPPH assay (10µmol Trolox eq/g DW), a threefold decrease in lutein (from 2.3 to 0.8mg/g) but a twofold increase in chlorophyll b (up to 30.0mg/g). Stauroneis sp. showed a downward response for the antioxidant assays, but its pigment yields did not vary significantly from the control. Diacronema sp. showed reduced antioxidant response and fucoxanthin content (from 4.0 to 0.2mg/g) when exposed to 0.5mM H2O2. R. violacea exposed to H2O2 returned enhanced antioxidant activity and proportions of EPA but was not significantly impacted in terms of pigment content. Results indicate that H2O2 can be used to induce stress and initiate metabolic changes in microalgae. The responses were however species-specific, which would require further dosage optimisation to modulate the yields of specific metabolites in individual species.

Çekerek Barajı'ndan (Yozgat, Turkey) Avlanan Gümüş Balığının (Atherina boyeri) Yağ Asidi ve Besin Kompozisyonundaki Mevsimsel Değişimleri

Seasonal variations of proximate and fatty acid compositions of the muscle tissue of sand smelt (Atherina boyeri) harvested in Cekerek (Sureyyabey) Dam were investigated. Seasonal nutritional composition of sand smelt muscle in October, March and July were found as 17.00%; 16.72%; 15.64% for protein, 1.95%; 2.00%; 2.86% for lipid, 79.25%; 79.17%; 78.06% for moisture and 1.80%; 2.10%; 2.49% ash, respectively. Sand smelt showed the lowest protein values in summer, while the highest protein values were observed in autumn and spring. The highest lipid content of sand smelt was found in summer (P &amp;lt; 0.05). The moisture content of sand smelt in summer was significantly (p&amp;lt;0.05) lower than those of the content in autumn and spring. The lowest ash content was observed in autumn (1.80%) whereas sand smelt gave the highest ash level was in summer. During the seasons, the proximate and FA composition values of sand smelt showed variations (p&amp;lt;0.05). Seasonal fatty acid compositions of sand smelt ranged from 24.63 to 25.69% for saturated fatty acid (SFA), from 20.75 to 26.43% for monounsaturated (MUFA), and from 28.29% to 36.11% polyunsaturated fatty acid (PUFA). Palmitic acid (16:0), stearic acid (18:0), palmitoleic acid (16:1ω7), oleic acid (18:1ω9), linoleic acid (LA, 18:2ω6), arachidonic acid (ARA, 20:4ω6), linolenic acid (18:3ω3), eicosapentaenoic acid (EPA, 20:5ω3) and docosahexaenoic acid (DHA, 22:6ω3) were major fatty acids of sand smelt in different seasons. The highest proportion of EPA (5.59-7.22%) and DHA (12.33-19.77%) were observed in spring. The results showed that sand smelt is good source of n-3 PUFAs and is rich in EPA+DHA for human nutrition.

Omega-3 phospholipids in Pacific blue mackerel (Scomber australasicus) processing by-products

The present study investigated phospholipid content, fatty acid composition and the positional distribution (sn-1,3 and sn-2) of n-3 fatty acids in four blue mackerel processing by-products (head, skin, roe, and male gonad). Total lipid was extracted using hexane/ethanol (1:2) and the analyses were carried out using NMR and GC-FID techniques. On the basis of g wet tissue, blue mackerel roe was a better source of phospholipids (38.6 µmol), compared to head (9.89 µmol), skin (13.5 µmol), and male gonad (10.0 µmol). Total lipid extracted from roe was found to have a higher proportion of n-3 fatty acids (44.4%) including EPA (11.3%) and DHA (27.5%), compared to head (total n-3 = 36.6%; EPA, 9.08%: DHA, 21.9%), skin (total n-3 = 34.8%; EPA, 9.63%; DHA, 19.5%) and male gonad (total n-3 = 42.5%; EPA, 12.1%; DHA, 24.7%). The proportion of EPA in the sn-2 position was substantially higher in fish roe (12.6%) compared to the other by-products (head, 1.91%; skin, 2.22%; male gonad, 2.02%). However, the DPA and DHA content in the sn-2 position did not vary significantly among the various parts (p > 0.05). Phospholipid esterified n-3 fatty acids were higher in roe (55.5%) compared to head (40.9%), skin (21.8%) and male gonad (32%). The present study suggests that blue mackerel roe is the best source of marine n-3 phospholipids among the blue mackerel commercially produced by-products.

Influence of Dietary Long-Chain Polyunsaturated Fatty Acids and ω6 to ω3 Ratios on Head Kidney Lipid Composition and Expression of Fatty Acid and Eicosanoid Metabolism Genes in Atlantic Salmon (Salmo salar).

The interaction of dietary eicosapentaenoic acid and docosahexaenoic acid (EPA+DHA) levels with omega-6 to omega-3 ratios (ω6:ω3), and their impact on head kidney lipid metabolism in farmed fish, are not fully elucidated. We investigated the influence of five plant-based diets (12-week exposure) with varying EPA+DHA levels (0.3, 1.0, or 1.4%) and ω6:ω3 (high ω6, high ω3, or balanced) on tissue lipid composition, and transcript expression of genes involved in fatty acid and eicosanoid metabolism in Atlantic salmon head kidney. Tissue fatty acid composition was reflective of the diet with respect to C18 PUFA and MUFA levels (% of total FA), and ω6:ω3 (0.5–1.5). Fish fed 0.3% EPA+DHA with high ω6 (0.3% EPA+DHA↑ω6) had the highest increase in proportions (1.7–2.3-fold) and in concentrations (1.4-1.8-fold) of arachidonic acid (ARA). EPA showed the greatest decrease in proportion and in concentration (by ~½) in the 0.3% EPA+DHA↑ω6 fed fish compared to the other treatments. However, no differences were observed in EPA proportions among salmon fed the high ω3 (0.3 and 1.0% EPA+DHA) and balanced (1.4% EPA+DHA) diets, and DHA proportions were similar among all treatments. Further, the transcript expression of elovl5a was lowest in the 0.3% EPA+DHA↑ω6 fed fish, and correlated positively with 20:3ω3, 20:4ω3 and EPA:ARA in the head kidney. This indicates that high dietary 18:3ω3 promoted the synthesis of ω3 LC-PUFA. Dietary EPA+DHA levels had a positive impact on elovl5a, fadsd5 and srebp1 expression, and these transcripts positively correlated with tissue ΣMUFA. This supported the hypothesis that LC-PUFA synthesis is positively influenced by tissue MUFA levels in Atlantic salmon. The expression of pparaa was higher in the 0.3% EPA+DHA↑ω6 compared to the 0.3% EPA+DHA↑ω3 fed fish. Finally, significant correlations between head kidney fatty acid composition and the expression of eicosanoid synthesis-related transcripts (i.e., 5loxa, 5loxb, cox1, cox2, ptges2, ptges3, and pgds) illustrated the constitutive relationships among fatty acids and eicosanoid metabolism in salmon.

A 16-week Randomized Controlled Trial of a Fish Oil and Whey Protein-Derived Supplement to Improve Physical Performance in Older Adults Losing Autonomy – A Pilot Study

Abstract Objectives Loss of autonomy is often the trigger for institutionalization of older adults. A nutritional intervention within a rehabilitation program may attenuate loss of muscle mass and function to enable continued autonomy in this understudied group of seniors. Objectives: 1) To assess the feasibility of a combined nutrient supplementation intervention with regards to recruitment, compliance, and completion of assessments in older adults losing autonomy; 2) to characterize this specific population. Methods Seniors taking part in a rehabilitation program were randomized to an intervention with a supplement (EXP: 2 g fish oil (EPA+ DHA) with 1500 IU vitamin D3 1x/d+ 20–30 g whey protein powder with 3 g leucine 2x/d) or placebo (CTR; corn oil and maltodextrin powder) for 16 weeks. Lean soft tissue mass (LM) and physical function were assessed. LM (DXA) was measured at weeks 0 and 16, handgrip and knee extension strength (dynamometry), physical performance tests and plasma phospholipid n-3 fatty acids (GCMS) were evaluated at weeks 0, 8 and 16. Results Over 2 y, 244 patients were screened, 46 were eligible (18.9%; 95% CI: 15.0, 22.8), 20 were randomized, 10 completed the study (n = 4 in EXP; n = 6 in CTR). Median age was 87 y (77–94 y; 75% women), 35% had low LM, 35% were frail, 85% were using a walking aid daily and physical performance was low, at baseline. Overall self-reported compliance to powder was 96% (95% CI: 83, 108) and to oil, 85% (95% CI: 63, 107). The EXP median protein intake alone surpassed the target 1.2–1.5 g/kg/d for older adults, without altering usual diet. Proportions of EPA and DHA increased significantly 3- and 1.5-fold respectively at week 8 in EXP, with no change in CTR. Participants were able to complete most assessments with sustained guidance. Conclusions Because of low eligibility limiting the pool of potential patients, the pilot study was interrupted as deemed non-feasible; however, compliance to supplements and the rigorous study assessments was high. Solutions to address recruitment, such as more liberal eligibility criteria, need to be considered in the design of a large-scale RCT before it can be carried out in this challenging population. Funding Sources Helen McCall Hutchison Award and Réseau québécois de la recherche sur le vieillissement of FRQS.

Contrasting effects of membrane enrichment with polyunsaturated fatty acids on phospholipid composition and cholesterol efflux from cholesterol-loaded J774 mouse or primary human macrophages

A high consumption of polyunsaturated fatty acids (PUFAs), particularly n-3 PUFAs, is atheroprotective. PUFAs incorporation into membrane phospholipids alters the functionality of membrane proteins. We studied the consequences of the in vitro supplementation of several PUFAs on the FA profiles and on ABCA1-dependent cholesterol efflux capacities from cholesterol-loaded macrophages. Arachidonic acid (AA, C20:4 n-6) and, to a lesser extent, eicosapentaenoic acid (EPA, C20:5 n-3), dose-dependently impaired cholesterol efflux from cholesterol-loaded J774 mouse macrophages without alterations in ABCA1 expression, whereas docosahexaenoic acid (DHA, C22:6 n-3) had no impact. AA cells exhibited higher proportions of arachidonic acid and adrenic acid (C22:4 n-6), its elongation product. EPA cells exhibited slightly higher proportions of EPA associated with much higher proportions of docosapentaenoic acid (C22:5 n-3), its elongation product and with lower proportions of AA. Conversely, both EPA and DHA and, to a lesser extent, AA decreased cholesterol efflux from cholesterol-loaded primary human macrophages (HMDM). The differences observed in FA profiles after PUFA supplementations were different from those observed for the J774 cells. In conclusion, we are the first to report that AA and EPA, but not DHA, have deleterious effects on the cardioprotective ABCA1 cholesterol efflux pathway from J774 foam cells. Moreover, the membrane incorporation of PUFAs does not have the same impact on cholesterol efflux from murine (J774) or human (HMDM) cholesterol-loaded macrophages. This finding emphasizes the key role of the cellular model in cholesterol efflux studies and may partly explain the heterogeneous literature data on the impact of PUFAs on cholesterol efflux.

Influence of environmental conditions, population density, and prey type on the lipid content in Baltic herring (Clupea harengus membras) from the northern Baltic Sea

Global climate change can affect the energy content of fish by altering their lipid physiology and consumption. We investigated the effects of different environmental stressors on the lipid content of the Baltic herring (Clupea harengus membras) from spawning ground samples that were collected annually in the northern Baltic Sea. During 1987–2014, the average lipid content of herring muscle decreased from 5%–6% (wet mass) to 1.5% (wet mass). Generalized linear mixed models indicated that sea water salinity and the size of the herring stock explained best the declining trend of lipid content. We estimated that the amount of the lipid storage incorporated in the spawning stock decreased by approximately 45% during the study, with respective energy content decreases. Fatty acid composition analysis revealed that herring lipids contained a high proportion of EPA (eicosapentaenoic acid; 20:5n-3) and DHA (docosahexaenoic acid; 22:6n-3), which likely originated from its main summertime prey, Limnocalanus macrurus. The results illustrate various climate change-induced processes leading to changes in the lipid content of the Baltic herring and, consequently, to changes in the energy flows of the northern Baltic ecosystem.

Urbanisation alters fatty acids in stream food webs.

Fatty acids are essential to macroinvertebrate growth and reproduction and can indicate food web structure and nutritional quality of basal resources. However, broad-scale examinations of how catchment land cover and associated stressors affect the proportions of fatty acids (FAs) in stream food webs are few.Here, we: (1) examine relationships among proportions of FAs among benthic periphyton and macroinvertebrate collector/gatherers, shredders, and predators; and (2) test if relationships between periphytic and macroinvertebrate FAs were altered due to the intensity of urban development in catchments.Proportions of the ≥20-C eicosapentaenoic acid (EPA 20:5ω3), arachidonic acid (ARA 20:4ω6), and docosahexaenoic acid (22:6ω3) indicated collector/gatherers had a diet richer in periphyton than in shredders, which had significantly lower proportions of these FAs. Collector/gatherers were in turn likely to be high-quality sources of ω3 and ≥ 20-C FAs for predators, which also had significantly greater EPA and ARA proportions than those in shredders. Linoleic (18:2ω6) and α-linolenic acid (18:3ω3) comprised the greatest proportions of FAs in shredders, which suggested a diet dominated by leaf litter and associated hyphomycetes.As catchment urbanisation increased, proportions of total ω3 FAs and EPA in periphyton were significantly greater. This pattern also was seen through macroinvertebrate consumers and predators, given that proportions of these FAs in macroinvertebrates also were significantly correlated with factors associated with catchment urbanisation. The significant increase in total ω3 FAs and EPA proportions within shredders indicated that periphyton growth, and their FAs, increased on leaf litter, probably due to greater nutrient concentrations associated with catchment urbanisation. Proportions of total ω6 FAs in biota were not significantly correlated with factors associated with urban development, which could indicate that they were of sufficient abundance for consumers regardless of urban intensity or possible changes in their sources.Our study provides an informative first step that identified notable differences in proportions of FAs among macroinvertebrates in urban streams and an increase in proportions of total ω3 FAs and EPA in periphyton, consumers, and predators as catchment urbanisation increases. Identifying how FA relationships within food webs change in response to catchment alterations and stressors could inform land use and management decisions by linking environmental changes to measures important to ecosystem outcomes.

The effect of camelina sativa oil and fish intakes on fatty acid compositions of blood lipid fractions

Background and aimsBlood lipid fractions serve as objective biomarkers of dietary fat intake. It is unclear which fatty acid pool most accurately reflects the dietary intakes of different n-3 PUFAs. We aimed to investigate the effect of fish and camelina sativa oil (CSO) intakes on fatty acid composition of erythrocyte membranes (EM), plasma phospholipids (PL), cholesteryl esters (CE) and triglycerides (TG). We also aimed to identify the most appropriate blood lipid fraction for assessing n-3 PUFA intake. Methods and resultsAltogether 79 volunteers with impaired glucose metabolism were randomly assigned either to CSO, fatty fish, lean fish or control groups for 12 weeks. Fatty acid compositions of lipid pools were measured by gas chromatography. The proportion of alpha-linolenic acid (ALA) increased in all lipid pools in the CSO group (false discovery rate (FDR) p < 0.001 for all). Similarly, the proportions of EPA and DHA increased in all lipid fractions in the fatty fish group (FDR p < 0.001 for EM, PL and CE; FDR p = 0.005 for TG; FDR p < 0.001 for EM, PL, CE; FDR p < 0.007 for TG, respectively). Changes in the dietary intakes of ALA, EPA and DHA correlated with the changes in their proportions in all lipid pools (r = 0.3–0.5, p < 0.05). ConclusionThere is no difference in the ability of blood lipid fractions in reflecting the dietary intake of different n-3 PUFAs over a time period of 12 weeks in subjects with high baseline omega-3 index.This trial was registered in Clinicaltrials.gov (NCT01768429)

Genetic effects of fatty acid composition in muscle of Atlantic salmon

BackgroundThe replacement of fish oil (FO) and fishmeal with plant ingredients in the diet of farmed Atlantic salmon has resulted in reduced levels of the health-promoting long-chain polyunsaturated omega-3 fatty acids (n-3 LC-PUFA) eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) in their filets. Previous studies showed the potential of selective breeding to increase n-3 LC-PUFA levels in salmon tissues, but knowledge on the genetic parameters for individual muscle fatty acids (FA) and their relationships with other traits is still lacking. Thus, we estimated genetic parameters for muscle content of individual FA, and their relationships with lipid deposition traits, muscle pigmentation, sea lice and pancreas disease in slaughter-sized Atlantic salmon. Our aim was to evaluate the selection potential for increased n-3 LC-PUFA content and provide insight into FA metabolism in Atlantic salmon muscle.ResultsAmong the n-3 PUFA, proportional contents of alpha-linolenic acid (ALA; 18:3n-3) and DHA had the highest heritability (0.26) and EPA the lowest (0.09). Genetic correlations of EPA and DHA proportions with muscle fat differed considerably, 0.60 and 0.01, respectively. The genetic correlation of DHA proportion with visceral fat was positive and high (0.61), whereas that of EPA proportion with lice density was negative. FA that are in close proximity along the bioconversion pathway showed positive correlations with each other, whereas the start (ALA) and end-point (DHA) of the pathway were negatively correlated (− 0.28), indicating active bioconversion of ALA to DHA in the muscle of fish fed high FO-diet.ConclusionsSince contents of individual FA in salmon muscle show additive genetic variation, changing FA composition by selective breeding is possible. Taken together, our results show that the heritabilities of individual n-3 LC-PUFA and their genetic correlations with other traits vary, which indicates that they play different roles in muscle lipid metabolism, and that proportional muscle contents of EPA and DHA are linked to body fat deposition. Thus, different selection strategies can be applied in order to increase the content of healthy omega-3 FAin the salmon muscle. We recommend selection for the proportion of EPA + DHA in the muscle because they are both essential FA and because such selection has no clear detrimental effects on other traits.

Effect of culture condition on the growth, biochemical composition and EPA production of alkaliphilic Nitzschia plea isolated in the Southeast of China.

To overcome the contamination in open pond, microalgal strain selection should focus on species with tolerability to extreme environments. In this study, a native alkaliphilic algae, diatom Nitzschia plea was obtained in Southeast of China, which could tolerate high concentration of NaHCO3 (0.15mol/L) and high pH (> 10). The effects of initial pH, light intensity and temperature on cell growth, biochemical composition and fatty acid profile of N. plea were investigated. Results indicated its specific growth rate could reach 1.2day-1, lipid content was in the range 14.6-30.2% of dry weight, eicosapntemacnioc acid (EPA, C20:5) accounted for around 15% of total fatty acids. Alkalic condition benefited for both cell growth and EPA synthesis. Appropriately increasing light intensity and temperature could improve cell growth rate and lipid synthesis, although the proportion of EPA in total fatty acids decreased slightly. The optimal culture condition (pH 9.00, temperature 35.0°C, light intensity 158.6µmol/m2s) was suggested for maximum yield of EPA based on the response surface model. The overall biomass productivity and EPA productivity were 0.301g/L/day and 7.43mg/L/day, respectively. In conclusion, alkalic environment was helpful for the steady operation of open pond cultivation of N. plea with the characteristics of fast growth rate and high EPA content, which exhibited its commercial value.

Erratum to: Closely related intertidal and deep-sea Halomonhystera species have distinct fatty acid compositions

The deep-sea free-living nematode Halomonhystera hermesi, dominant in the sulphidic sediments of the Hakon Mosby mud volcano (1280 m, Barent sea slope), is part of the mainly estuarine Halomonhystera disjuncta species complex consisting of five cryptic species (GD1–GD5). Cryptic species have a very similar morphology raising questions on their specific environmental differences. This study analyzed total fatty acid (FA) compositions of H. hermesi and GD1, one of H. hermesi’s closest relatives. Additionally, we experimentally investigated the effect of a temperature reduction, salinity increase and sulphide concentrations on GD1’s FA composition. Because nematodes are expected to have low amounts of storage FA, total FA compositions most likely reflect FA contents of cellular membranes. The deep-sea nematode H. hermesi had significantly lower saturation levels and increased highly unsaturated fatty acid (HUFAs) proportions due to the presence of docosahexanoic acid (DHA—22:6ω3) and higher eicosapentaenoic acid (EPA—20:5ω3) proportions. HUFAs were absent in H. hermesi’s food source indicating the ability and need for this nematode to synthesize HUFAs in a deep-sea environment. Our experimental data revealed that only a decrease in temperature resulted in lower saturated fatty acids proportions, indicating that the FA content of H. hermesi is most likely a response to temperature but not to sulphide concentrations or salinity differences. In experimental nematodes, EPA proportions were low and DHA was absent indicating that other factors than temperature, salinity and sulphides mediate the presence of these HUFAs in H. hermesi.

Squalene modulates fatty acid metabolism: Enhanced EPA/DHA in obese/diabetic mice (KK‐Ay) model

Biosynthesis of long‐chain n‐3 fatty acids from precursors is limited. In vivo effect of squalene (SQ) on the metabolic fate of n‐3 fatty acid precursors in obese/diabetic KK‐Ay rodent model was evaluated in our work. Soybean oil, being rich in ALA (18:3 n‐3; a known precursor of EPA/DHA), was chosen as the n‐3 fatty acid precursor rich source. A high‐fat diet (20%) containing 7% soybean oil (SO) was fed to obesity/diabetes‐prone male KK‐Ay mice (control). In the case of diets fed to test groups, soybean oil was replaced with 5% SO and 2% SQ. Hepatic DHA levels increased (four fold) in SQ fed group over control (p &lt; 0.05). Gene and protein expressions of Δ5 and Δ6 desaturases, key enzymes involved in the fatty acid metabolism, further supported the results. Also, SQ exhibited a hypotriglyceridemic and hypoglycemic effect. The results clearly indicated the effect of SQ in modulating the n‐3 fatty acid metabolism, including EPA/DHA synthesis in the presence of n‐3 fatty acid precursor. This is the first report of enhancement of in vivo DHA/EPA by SQ and in turn, modulating the physiological fatty acid profile.Practical applications: Squalene (SQ) is an important marine biofunctional material that is found in some terrestrial sources as well. Squalene, being a cholesterol precursor, forms an interesting subject of research for its effect in vivo. SQ significantly enhanced proportions of EPA and/or DHA when their n‐3 fatty acid precursors were available in the diet. The study further establishes the usefulness of SQ in functional food formulations. The work provides an important basis for further evaluation of the role of SQ in normal and disease conditions.KK‐Ay mice were fed high fat/sucrose diet to induce obesity/diabetes. Fat source in control diet was lard and soybean oil while experimental group diet contained 2% squalene + 13% lard + 5% soybean oil. Feeding squalene for 4 weeks modulated fatty acid metabolism with increased docosahexaenoic acid (DHA) and decrease in triglycerides (TG), compared to control. The enhanced DHA in the fatty acid profile was supported by upregulated mRNA expression of Δ5‐desaturase enzyme and protein expression of Δ5 and Δ6 desaturases (FADS1 and FADS2). Additionally, squalene had a hypoglycemic effect in the mice.

Dummy regression analysis for modelling the nutritionally tailored fillet fatty acid composition of turbot and sole using gilthead sea bream as a reference subgroup category

Farmed turbot and sole were sampled at different stages of the production cycle for analysis of fillet lipid content and fatty acid (FA) composition. The entire data set along with our own published data on gilthead sea bream were fitted to dummy regression equations with turbot and sole as dummy variables, gilthead sea bream as a reference subgroup category, and diet FA composition and fillet lipid content as independent variables. The relative contribution of each independent variable to the total variance was found to vary within and among FAs and fish species, but strong correlation coefficients (0.76 0.99) were found for almost all of the FA equations, including saturated FAs, monoenes and long-chain polyunsaturated fatty acids (PUFA) of n-3 and n-6 series. Given the differences in lipogenic activities of the fish species, major interaction effects between fillet lipid content and dummy variables were found for monoenes and saturated FAs. The proposed equations (hosted at www.nutrigroup-iats.org/aquafat) were able to fit different proportions of EPA, DPA and DHA underlying the fish species differences in FA desaturation/elongation pathways. The robustness of the model was proven with extra data from the three fish species, allowing a close linear association near to equality for the scatter plot of observed and predicted values.