Abstract: 【Aim】 The present study aims to clone Caspase family gene in Bombyx mori and to investigate its function preliminarily using RNAi. 【Methods】 A new gene of Caspase family was cloned by rapid amplification of cDNA ends (RACE), and then its functions in apoptosis were analyzed by RNAi and flow cytometry. 【Results】 The cloned Caspase family gene was denominated BmCaspase-X in B.mori, the full length is 2 105 bp, and the open reading frame is 1 494 bp, coding a protein of 497 aa with an estimated molecular mass of 57.8 kD and pI of 5.29. BmCaspase-X contains the typical characteristics of Caspase family. Phylogenetic analysis showed that BmCaspase-X and ICE of the silkworm cluster with Caspase-4 homologs from other insects firstly, and then cluster with Caspase members with long precursor structure domain from other insects. RNAi of BmCaspase-X in BmE-SWU1 cells did not cause significant apoptosis effect. 【Conclusion】 The new BmCaspase-X, with the typical characteristics of Caspase family, should be classified into the Caspase family. The preliminary RNAi data show that BmCaspase-X seems not to cause apoptosis in silkworm cells. This study lays a foundation for further functional investigation on BmCaspase-X.

Key words: Bombyx mori, BmCaspase-X, gene cloning, RNAi, apoptosis