Fatty Acid Composition and Fatty Acid Associated Gene-Expression in Gilthead Sea Bream (Sparus aurata) are Affected by Low-Fish Oil Diets, Dietary Resveratrol, and Holding Temperature.

To sustainably produce marine fish with a high lipid quality rich in omega-3 fatty acids, alternative sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are being identified. Moreover, the use of bioactive compounds that would stimulate the in vivo fatty acid synthesis, such as resveratrol (RV), would reduce the dependence on fish oil in aquafeeds. Gilthead sea bream (Sparus aurata) were fed four experimental diets combining two fish oil levels (6% dry matter (DM); 2% DM) with or without 0.15% DM resveratrol supplementation (F6, F2, F6 + RV, F2 + RV) for two months. Additionally, the fish were challenged either at 19 °C or 23 °C. A higher water temperature promoted their feed intake and growth, resulting in an increased crude lipid content irrespective of dietary treatment. The fatty acid composition of different tissues was significantly affected by the holding temperature and dietary fish oil level. The dietary RV significantly affected the hepatic EPA and DHA content of fish held at 19 °C. The observed effect of RV may be partly explained by alterations of the mRNA steady-state levels of ∆6-desaturase and ß-oxidation-related genes. Besides the relevant results concerning RV-mediated regulation of fatty acid synthesis in marine fish, further studies need to be conducted to clarify the potential value of RV to enhance fillet lipid quality.

Dietary Buglossoides arvensis Oil as a Potential Candidate to Substitute Fish Oil in Rainbow Trout Diets.

The utilization of vegetable oils in salmonid diets substantially decreased the body content of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA), and thus the product quality for human consumption. Therefore, new ingredients for aquaculture feeds are needed that maximize the deposition of health-promoting n-3 LC-PUFA. This study investigated Buglossoides arvensis (Ahiflower) oil, a plant oil rich in alpha-linolenic acid (18:3n-3, ALA) and stearidonic acid (18:4n-3, SDA), as a source of n-3 fatty acids in rainbow trout (Oncorhynchus mykiss) nutrition. Rainbow trout (87.4 ± 0.6 g) were fed for 56 days. The oils of the control diet (FV) were substituted by Ahiflower oil at 33%, 66%, and 100% (A33, A66, A100). Dietary Ahiflower oil increased the final body weights of fish. mRNA steady state levels of fatty acyl desaturase 2a (delta-6) (fads2a(d6)) and 2b (delta-5) (fads2b(d5)) as well as carnitine palmitoyl transferase 1 a (cpt1a) were not altered by dietary treatments. In contrast, cpt1c mRNA steady state levels were significantly downregulated in samples of fish fed A66 and A100. Significantly higher eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) levels were found in the liver and significantly higher EPA levels in the fillet of rainbow trout of A66 and A100 compared to FV. The content of DHA in fillets of fish fed Ahiflower oil was not significantly different to fish fed FV. Thus, high dietary amounts of Ahiflower oil can compensate for reduced dietary EPA and DHA levels.

Combination of Dietary Ahiflower Oil and Equol Enhances Long-Chain Polyunsaturated Fatty Acid Levels in Rainbow Trout Tissues.

Equol and Ahiflower oil have been shown to increase either eicosapentaenoic acid (EPA, 20:5n-3) or docosahexaenoic acid (DHA, 22:6n-3) levels in tissues of rainbow trout when applied individually. Thus, we investigated whether the combination of an Ahiflower oil-based diet and equol might increase both, EPA and DHA levels, in rainbow trout. Rainbow trout (87.1 ± 0.3 g) were fed with five diets for 8 weeks. A diet based on a blend of fish and vegetable oils (FV) served as a reference diet. The four experimental diets contained a blend of Ahiflower oil and vegetable oils (AV). The AV-diets were supplemented with equol by 0.0%, 0.1%, 0.2%, and 0.3% DM of the diet (AV-C, AV-EQ1, AV-EQ2, and AV-EQ3). The dietary treatments did not affect growth performance of fish and chemical nutrient composition of the whole body samples. Fish fed with the equol diets showed dose-dependently increased liver weights and 18:0 liver levels. The content of EPA showed no consistent pattern between tissues but all AV-groups were characterized by higher liver EPA values than FV. DHA values of AV-EQ2 and AV-EQ3 were similar to FV in fillet, tended to be the highest in the whole body and were significantly higher in liver compared to FV. In contrast, mRNA steady state levels of fatty acyl desaturase 2a (delta-6) [fads2a(d6)] were not affected by the dietary treatments. In conclusion, the combination of dietary Ahiflower oil and equol (0.2% and 0.3%) seems to affect the fatty acid metabolism of rainbow trout positively to increase DHA tissue levels.

Self-assembled α-Tocopherol Transfer Protein Nanoparticles Promote Vitamin E Delivery Across an Endothelial Barrier.

Vitamin E is one of the most important natural antioxidants, protecting polyunsaturated fatty acids in the membranes of cells. Among different chemical isoforms assimilated from dietary regimes, RRR-α-tocopherol is the only one retained in higher animals. This is possible thanks to α-Tocopherol Transfer Protein (α-TTP), which extracts α-tocopherol from endosomal compartments in liver cells, facilitating its distribution into the body. Here we show that, upon binding to its substrate, α-TTP acquires tendency to aggregation into thermodynamically stable high molecular weight oligomers. Determination of the structure of such aggregates by X-ray crystallography revealed a spheroidal particle formed by 24 protein monomers. Oligomerization is triggered by refolding of the N-terminus. Experiments with cultured cell monolayers demonstrate that the same oligomers are efficiently transported through an endothelial barrier (HUVEC) and not through an epithelial one (Caco-2). Discovery of a human endogenous transport protein with intrinsic capability of crossing endothelial tissues opens to new ways of drug delivery into the brain or other tissues protected by endothelial barriers.

Olive oil bioactives protect pigs against experimentally-induced chronic inflammation independently of alterations in gut microbiota.

Subclinical chronic inflammation (SCI) is associated with impaired animal growth. Previous work has demonstrated that olive-derived plant bioactives exhibit anti-inflammatory properties that could possibly counteract the growth-depressing effects of SCI. To test this hypothesis and define the underlying mechanism, we conducted a 30-day study in which piglets fed an olive-oil bioactive extract (OBE) and their control counterparts (C+) were injected repeatedly during the last 10 days of the study with increasing doses of Escherichia coli lipopolysaccharides (LPS) to induce SCI. A third group of piglets remained untreated throughout the study and served as a negative control (C-). In C+ pigs, SCI increased the circulating concentration of interleukin 1 beta (p < 0.001) and decreased feed ingestion (p < 0.05) and weight gain (p < 0.05). These responses were not observed in OBE animals. Although intestinal inflammation and colonic microbial ecology was not altered by treatments, OBE enhanced ileal mRNA abundance of tight and adherens junctional proteins (p < 0.05) and plasma recovery of mannitol (p < 0.05) compared with C+ and C-. In line with these findings, OBE improved transepithelial electrical resistance (p < 0.01) in TNF-α-challenged Caco-2/TC-7 cells, and repressed the production of inflammatory cytokines (p < 0.05) in LPS-stimulated macrophages. In summary, this work demonstrates that OBE attenuates the suppressing effect of SCI on animal growth through a mechanism that appears to involve improvements in intestinal integrity unrelated to alterations in gut microbial ecology and function.