Functions Of Apoptosis-related PjCaspase Gene From Peneaus Japonicus

Shrimp is one of the most important species in aquaculture, but it has been blocked by diseases caused by white spot syndrome virus (WSSV) in the world since 1990's. So it is important to study the innate immunity of shrimp and explore new approaches against the diseases. In our previous study, a fragment of a cDNA related to apoptosis was obtained in Peneaus japonicus by SSH. To further realize its role in shrimp antiviral immunity, in this investigation, this gene was characterized, which would be helpful for shrimp disease control.The full-length cDNA was obtained with 5'and 3'RACEs in Peneaus japonicus. It contained an open reading frame (ORF) of 1524bp encoding 508 amino acids, which was homologous with caspase protein family. This ORF was named as PjCaspase gene. Its DNA sequence revealed that PjCaspase gene cotained 2 introns and 3 exons. Its promoter was obtained using genome walker kit and further confirmed by functional analysis.After cloning of PjCaspase gene into prokaryotic vector pGEX-4T-2, the fusion protein was obtained, which presented enzyme activity of caspase. This gene was transcribed and translated in all shrimp tissues except for heart as revealed by RT-PCR, Northern blot and Western blot. Total RNAs of hepatopancreas from WSSV-infected and WSSV-resistant shrimp were extracted and subjected to real-time PCR. The results indicated that the PjCaspase gene was upregulated in WSSV-resistant shrimp, suggesting that it was involved in the shrimp antiviral immunity. To further realize the role of PjCaspase in apoptosis, RNAi was used to silence the PjCaspase gene. The results showed that the apoptosis was inhibited when the transcription of PjCaspase was inhibited, indicating that this gene played a very important role in apoptosis.In this premilitary study, it was found that the PjCaspase gene presented gene diversity. The gene diversity in WSSV-resistant shrimp was...