s reveal that the caspase family members are functionally conserved between species. Silkworm initiator caspase homologs BmDronc and BmDredd Caspase 9 has a crucial role during apoptosis from nematodes to mammals. Recently, Dronc homologs have been identified in the genomes of Aedes aegypti and Anopheles gambiae. The mammalian caspase 9 homolog BmDronc was identified in silkworm, which has two splice variants with common translation initiation and Batimastat termination sites, named BmDroncL and BmDroncS respectively, and verified by cloning from silkworm BmE cells. Only BmDroncS has a CARD domain and a small subunit, while BmDroncL has the typical caspase family domains. The sequence identities of silkworm BmDroncL with homologs from Homo sapiens, Droso phila melanogaster, and Aedes aegypti are 24%, 29% and 35%, respectively.

An ortholog of Drosophila Dredd was also found in the silkworm, named BmDredd, consistent with the data submitted to NCBI. The result of domain prediction revealed that BmDredd, AeDredd and DmDredd have long prodomains but no domains that mark them as initiator caspases, unlike mammalian caspase 8 with DEDs. The genetic relationship between caspases from silkworm, Aedes aegypti and Drosophila is much closer than with other species. The sequence identities and similarities of BmDredd with DmDredd and AeDredd are 28% and 45%, 27% and 45%, respectively. Silkworm effector caspases Bmcaspase 1 is the first effector caspase reported in Bombyx mori. Pei and colleagues identified Bmcas pase 1 from Bombyx mori BmN cells.

Bmcaspase 1 has only one exon, is 1291 bp long, coding for 293aa, and is located on chro mosome 10. Bmcaspase 1 has the classic short prodomain, with the characteristic QACXG sequence in the large subunit and the small sub unit. From the evolution ary relationship, BmCaspase 1 clusters into the same group with DmICE and DmDcp 1 of Drosophila mela noganster. Duan and colleagues identified BmICE from the Bombyx mori integumentum, and Song and collea gues have cloned BmICE 2 and BmICE 5 according to the sequence sub mitted by Duan from BmE cells. All these genes have the characteristic QRCAG sequence and the typi cal large small subunit configuration of caspase family members. We aligned and analyzed the sequences of these three coding sequences with the silk worm 9�� genome database, and the result reveals that BmICE, BmICE 2 and BmICE 5 have the same transla tion and termination sites.

BmICE has seven exons, BmICE 2 has eight exons and BmICE 5 has nine exons, the splicing differences occur after the seventh exon. Our results demonstrated that there is an additional cas pase family member in Bombyx mori. Because it has not been reported in Bombyx mori previously, we named it BmCaspase New. Bmcaspase N is 1071 bp long, coding for 356 aa, and possesses the characteristic structure of caspase effector subfamily members, including a short prodomain and CASc domain with the QACXG sequence. Phylogenetic analysis revealed that Bmcaspase