Characterization of the Gene and Its Association with Resistance Traits in (Linnaeus, 1758).

The MMPs are endogenous proteolytic enzymes that require zinc and calcium as cofactors. is one of the most complex matrix metalloproteinases in the gelatinase family and has many biological functions. In mammals, mmp9 is thought to be closely associated with cancer. However, studies in fish have rarely been reported. In this study, to understand the expression pattern of the gene and its association with the resistance of to , the sequence of the MMP9 gene was obtained from the genome database. The expression profiles were measured by qRT-PCR, the SNPs were screened by direct sequencing, and genotyping was performed. The gene contained a 2058 bp ORF encoding a putative amino acid sequence of 685 residues. The homology of the in teleosts was more than 85%, and the genome structure of was conserved in chordates. The gene was expressed in different tissues of healthy individuals and was highly expressed in the fin, the gill, the liver and the skin tissues. The expression in the skin of the infected site and its adjacent sites increased significantly after infection. Two SNPs were identified in the gene, and the SNP (+400A/G) located in the first intron was found to be significantly associated with the susceptibility/resistance to . These findings suggest that may play an important role in the immune response of against .