Impact of exogenous glutamine on growth-related gene expression and metabolic pathways in Trachinotus blochii

In recent years, the scale of Trachinotus blochii aquaculture has been expanding. Our previous research identified glutamine metabolism related genes as key regulators of T. blochii growth. Recently, fish essential amino acids have been developed as nutritional additives in aquaculture feed. To explore the effects of glutamine on growth related genes in T. blochii, we formulated T. blochii feed and conducted a feeding trial. No exogenous glutamine was added to the control group, alongside four experimental groups supplemented with 0.3 %, 0.6 %, 0.9 %, and 1.2 % exogenous glutamine, respectively. After eight weeks feeding, liver enzyme activity analysis indicated that adding 0.3 % and 0.6 % exogenous glutamine reduced MDA levels. Similarly, T-AOC and T-SOD activities were higher in the livers of T. blochii supplemented with 0.3 % glutamine. Liver samples were also collected for transcriptome sequencing. The results showed that the oxidative phosphorylation pathway was activated, and the fat digestion system pathway was significantly enriched following the addition of exogenous glutamine. Co-mRNA network analysis showed enrichment in a large number of genes related to the ubiquinone oxidoreductase family. However, significant differences were observed in disease related genes when glutamine was added at 0.9 % and 1.2 %. In summary, supplementing 0.3 % to 0.6 % glutamine in T. blochii feed can enhance amino acid metabolism and fat utilization. It can also activate pathways related to oxidative phosphorylation and fat digestion and absorption, thereby making more energy available to influence other physiological factors. These results provide an important reference for the optimization of the feed formula for T. blochii.