Cloning and expression analysis of hypoxia-related gene HO in cobia

The heme oxygenase gene plays a role in many biological processes and is an important protective factor in hypoxic stress. Research on the HO gene of fishes has attracted increasing attention, but there is yet little information about the cobia (Rachycentron canadum)heme oxygenase gene. In this study, the full-length cDNA of the cobia heme oxygenase gene (heme oxygenase, HO) was cloned using rapid amplification of cDNA ends technology. The full-length cDNA was 1639 bp and the open reading frame (ORF) was 840 bp encoding 279 amino acids, with 5 '-UTR 518 bp and 3 '-UTR 281 bp. The results of real-time quantitative PCR showed that cobia HO was expressed in all the tissues tested, with the highest expression in gills. The mRNA expression of gill HO increased after hypoxia stress. There was no significant change in the expression of HO mRNA in the liver after hypoxia stress. The amino acid sequences of HO in diverse fish and mammals have varying levels of homology. Our results indicate that the biological functions of HO may be similar in fish and mammals, suggesting an important protective factor in response to hypoxic stress.