cDNA cloning of caspase2 gene in Fenneropenaeus chinensis and its expression analysis in WSSV infection

In this study, full-length cDNA sequence of caspase2 gene from Fenneropenaeus chinensis was first cloned using RACE method. The full-length cDNA sequence of caspase2 was 1517 bp, which contains a 78 bp 5'-UTR, 515 bp 3'-UTR and 924 bp open reading frame that encoded 307 amino acid residues, which had the isoelectric point(PI) of 7.62 and molecular mass of 34.21 ku. Homology analysis revealed that the amnio acid sequences of caspase2 highly identified with caspase family of other species, for example, it had 88% identity with caspase2 of Litopenaeus vannamei, and had 80% identity with caspase of Penaeus monodon. The phylogenetic analysis showed that Fenneropenaeus chinensis caspase2 was in the same class with other arthropods caspase. The expression levels of caspase2 gene in different tissues were analyzed by quantitative real-time PCR. The results showed that the highest level of caspase2 gene was in hepatopancreas. Real-time PCR analysis showed that the expression level of caspase2 was up-regulated distinctly in muscle, hepatopancreas and gill after stimulation with WSSV infection, and caspase2 showed different expression profiles. The results implied that caspase2 might play an important role in WSSV-challenge response of F. chinensis.