Evolution, characterization, and immune response function of long-chain acyl-CoA synthetase genes in rainbow trout (Oncorhynchus mykiss) under hypoxic stress

Long-chain acyl-CoA synthetases (Acsls), members of the acyl-activating enzyme superfamily, haves been systematically characterized in mammals and certain fishes, but the research on their involvement in reproductive development and hypoxic stress response in rainbow trout remains limited. In this study, we investigated the acsl gene structure and physical and chemical characteristics and the evolutionary relationship among acsl genes using the NCBI/Ensembl database. Using hypoxia treatment experiment, acsl gene expression in various organs and its regulation were investigated. A total of 11 acsl genes were identified in rainbow trout. Phylogenetic analyses found that acsl genes in rainbow trout were clustered into two clades: acsl3/4 and acsl1/2/5/6, and the additional gene duplication observed resulted from the third round of genome duplication unique to teleosts. Multiple sequence alignment and conserved motif analyses showed that the sequence of acsl proteins was highly conserved. Real-time quantitative PCR (RT-qPCR) showed that the acsl genes were highly expressed in immune tissues (liver and head kidney). Under hypoxia, the expression of acsl genes was upregulated, suggesting that they enhance the tolerance to hypoxia and are involved in the immune response in rainbow trout. Our study provides valuable insights into teleost evolution and effects of hypoxia on biological immunity and form a basis for further research on the functional characteristics of acsl genes.

Automated summary

In this study, the structure and characteristics of acsl genes were investigated in rainbow trout, and their involvement in biological immunity and hypoxic stress response was explored. It was found that acsl genes were highly conserved in rainbow trout and showed high expression in immune tissues. Furthermore, the expression of acsl genes was upregulated under hypoxia, indicating their role in enhancing tolerance to hypoxia and immune response. These findings provide important insights into teleost evolution and the effects of hypoxia on biological immunity.