The antioxidant ability, histology, proximate, amino acid and fatty acid compositions, and transcriptome analysis of muscle in juvenile hybrid grouper (♀ Epinephelus fuscoguttatus x ♂ Epinephelus lanceolatus) fed with oxidized fish oil

The hybrid grouper (female Epinephelus fuscoguttatus x male Epinephelus lanceolatus), as an important economic fish, has attracted much attention for its meat quality, and its meat quality is closely related to the composition of diet. In this study, a rearing experiment was conducted for 65 days with diets containing 0, 3, 6, and 9% oxidized fish oil (referred to as R, L, M and H group respectively) to investigate the effects of oxidized fish oil on the antioxidant ability, histology, proximate, amino acid and fatty acid compositions, and transcriptome analysis of muscle in juvenile hybrid grouper. As the proportion of oxidized fish oil increased in diet, the vitamin E concentration and antioxidant enzymes activities decreased significantly in muscle, but malondialdehyde (MDA) and total antioxidant capacity (T-AOC) showed the opposite trend, and the destruction of muscle fiber by oxidative stress was increasing. At the same time, the proximate composition, amino acid and fatty acid content in muscle were affected by oxidative stress. A total of 43,469 unigenes were obtained in transcriptome with 76 differentially expressed genes. There were 3 significant pathways including vitamin B6 metabolism, biosynthesis of amino acids, and p53 signaling pathway, and the significant pathways involved 5 different genes including phosphatase, phosphoglycerate mutase 2 (PGAM2), S-adenosylmethionine synthase isoform type-2 (SAM2), protein shisa-5-like (SHISA5), and growth arrest and DNA damage-inducible protein GADD45 beta-like (GADD45 beta). In conclusion, the dietary oxidized fish oil caused oxidative stress of muscle, and oxidative stress destroyed muscle fiber structure. Meanwhile, the oxidative stress changed muscle nutrition. In addition, the oxidative stress changed the muscle transcriptome profile.

Automated summary

As the proportion of oxidized fish oil increased in diet, the vitamin E concentration and antioxidant enzymes activities in muscle decreased significantly, while malondialdehyde (MDA) and total antioxidant capacity (T-AOC) increased, leading to the destruction of muscle fiber structure by oxidative stress. Additionally, the oxidative stress altered muscle nutrition and transcriptome profile.