Cloning, Expression And Function Analysis Of A Caspase Gene In Chinese Shrimp Fenneropenaeus Chinensis

shrimp is one of the most important species in aquaculture. Nevertheless, the outbreak of diseases has significantly compromised shrimp aquaculture worldwide since 1993, and shrimp farmings in China also suffered severely from the catastrophic epidemics. The key point to solve this problem is to explore the immune mechanism of shrimp. So it is important to study the innate immunity of shrimp and explore new approaches against the diseases.In this study, degenerate primers were designed according to the sequence homologous with the same genes from other species. Then PCR was used to obtain the full lengths of caspase (FcCasp) in Chinese shrimp Fenneropenaeus chinensis.The entire 954 bp open reading frame encoded a deduced protein of 317 amino acids with a predicted molecular weight of 35592.8 Da and an isoelectric point of 5.76. A typical caspase family protease active site QACRG pentapeptide was located from amino acids 190 to 194. The P20 subunit was located at aa 67-196 while the P10 subunit was located at aa 218-317.The expression of the above gene was analyzed in 7 tissues of shrimp including hemocytes, lymphoid organ, intestine, hepatopancreas etc. FcCasp transcripts in hemocytes and lymphoid organ are higher than those in the other tissues. Since the hemocytes and lymphoid organ play very important roles in the immune reaction of shrimp, FcCasp might act as important immune factors in shrimp.Real time PCR technique was applied to quantify the transcripts of FcCasp gene in hepatopancreas when shrimps were challenged by WSSV. After challenged with WSSV, total RNAs of hepatopancreas from WSSV-infected were extracted in different time points. The expression profile of FcCasp showed a wavy changing curve in hepatopancreas, which indicate that FcCasp may play an important function in apoptosis when shrimp were challenged by WSSV. To further realize the role of FcCasp in apoptosis, RNAi was used to silence the FcCasp gene. The results showed that the apoptosis was inhibited when the transcription of FcCasp was inhibited, indicating that this gene played a very important role in apoptosis.