Molecular cloning of <Emphasis Type="Italic">BmTUDOR-SN</Emphasis> and analysis of its role in the RNAi pathway in the silkworm, <Emphasis Type="Italic">Bombyx mori</Emphasis> (Lepidoptera: Bombycidae)

Tudor-sn, a conserved nuclease, was first isolated from RNA-induced silencing complex (RISC) and was subsequently implicated in the RNA interference (RNAi) pathway in humans, flies and nematodes. However, in the silkworm, Bombyx mori L, the RNAi mechanism and the components of RISC were quite unclear. Here, we cloned the full-length cDNA of TUDOR-SN (BmTUDOR-SN) from the silkworm. Phylogenetic analysis revealed that BmTudor-sn had a high homology with Tudor-sn proteins in other insects. Fluorescent microscopic observation indicated that the subcellular localization of enhanced green fluorescent protein fused BmTudor-sn was mainly in the cytoplasm of silkworm BmN4 cells. Knockdown of BmTUDOR-SN did not, however, affect the RNAi efficiency in BmN4 cells.