Impact of Dietary Docosahexaenoic Acid : Eicosapentaenoic Acid Ratio on Growth, Fatty Acid Composition, Lipid Metabolism, and Antioxidant Status of Juvenile Hybrid Grouper (Brown‐marbled Grouper Epinephelus fuscoguttatus ♀ × Giant Grouper E. lanceolatus ♂)

Abstract

The present study was conducted to evaluate the effects of dietary docosahexaenoic acid : eicosapentaenoic acid (DHA:EPA) ratio on growth, lipid metabolism, and antioxidant status of hybrid grouper (Brown-marbled Grouper Epinephelus fuscoguttatus ♀ × Giant Grouper E. lanceolatus ♂). Fish (initial body weight = 20.8 ± 0.03 g; mean ± SE) were fed six different isoproteic (53%) and isolipidic (7%) diets containing graded DHA:EPA ratios (D/E) of 0.54, 0.97, 1.51, 2.01, 2.41, and 2.85. No significant difference in weight gain was recorded in fish fed with different dietary DHA:EPA ratios. The DHA:EPA ratio in fish muscle was significantly increased as the dietary ratio increased. Relative messenger RNA expression of hepatic elongase of very long fatty acids 5 (elovl5*) and delta-6 fatty acyl desaturase (Δ6 fad*) in the D/E 2.41 and 2.85 groups was significantly higher than that in the other treatments. Lipid droplet accumulation was significantly higher in the liver of the D/E 0.54 and 0.97 groups than in the other groups. Lipogenesis-related genes (fatty acid synthase [FAS*] and acetyl coenzyme A carboxylase [ACC*]) were up-regulated by lower dietary DHA:EPA ratios (0.54 and 0.97), whereas lipolysis-related genes (peroxisome proliferator-activated receptor alpha [PPARα*] and hormone-sensitive lipase [HSL*]) were down-regulated. The expression of genes related to antioxidative capacity, including nuclear factor erythroid 2-related factor 2 (Nrf2*), manganese superoxide dismutase (MnSOD*), and peroxiredoxin (Prx*), was significantly down-regulated in the D/E 1.51 and 2.01 groups compared with other treatments, while Kelch-like ECH-associated protein 1 (Keap1*) was upregulated. The above results suggest that dietary DHA:EPA ratio influences muscle fatty acid composition and lipid metabolism by altering the expression of lipogenesis-and lipolysis-related genes, and dietary DHA:EPA ratio may also regulate the antioxidant capacity of juvenile hybrid grouper.

Valorization of Side Stream Products from Sea Cage Fattened Bluefin Tuna (Thunnus thynnus): Production and In Vitro Bioactivity Evaluation of Enriched ω-3 Polyunsaturated Fatty Acids

“…The fatty acid synthase ( fas ) gene is a marker of de novo lipogenesis involved in the conversion of acetyl-CoA and malonyl-CoA to palmitate [ 92 ]. Cells incubated with TFA and PUFA-SPd were significantly upregulated ( p < 0.05) compared to the control ( Figure 2 ).…”