Transcriptomic analysis of juvenile cobia in response to hypoxic stress

Abstract

Cobia is an important cultured marine fish species in southern China. It is characterised by fast growth. Due to the effects of climate change on water oxygen levels and seawater temperatures, understanding the influence of environmental challenges on cobia culture has become very important. In this study, to explore the stress and adaptability of cobia (Rachycentron canadum) during hypoxia-reoxygenation conditions, the fish were exposed to an oxygen-deficient environment with dissolved oxygen (DO) level of 2.64 ± 0.25 mg/L. Liver tissue transcriptome sequencing was detected in the fish at acute hypoxia stress, after which fish were returned to normal DO levels (6.34 mg/L) for 8, 24, and 48 h. Comparative analysis of liver transcriptomes revealed that there were 1689, 651, 236, and 1150 differential genes in the hypoxia stress group (SC), reoxygenation-8h group (R8), reoxygenation-24h group (R24), and reoxygenation-48h group (R48), respectively. The differentially expressed genes were compared with the GO database. The main aggregated genes were related to gene ontology functional elements such as ribosome structural components, matrix-dependent cell migration, hormone activity, and oxidoreductase activity. The differentially expressed genes were compared with the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, and a total of 43,054 differentially expressed genes were found to be enriched in 212 cases. For the first time, gene expression patterns in the liver of a juvenile’s cobia were examined in response to hypoxia. The results of this study contribute to further clarifying hypoxia’s effects on the liver of marine fish.