Identification and functional analysis of a testis‑biased gene encoding serine/arginine‑rich protein in silkworm, Bombyx mori

Spermatogenesis is a fundamental process in sexual reproduction. In this study, we cloned a 716-bp cDNA of a testis-biased gene in Bombyx mori, named as BmRS-TS, which encodes a polypeptide of 164 amino acids, containing 26.7% arginine and serine residues. Sequence similarity analysis showed that BmRS-TS is a lepidopteran-specific gene. Results of RT-PCR and Western analysis revealed that BmRS-TS was expressed predominantly in the testis. Immunohistochemistry assay showed that the BmRS-TS protein was mostly located in primary spermatocytes. Moreover, knockdown of BmRS-TS by RNA interference (RNAi) showed that the morphology of the mature sperm was abnormal and that sperm bundles were broken up. Our results suggest that BmRS-TS plays an important role in silkworm spermatogenesis and provide some clues for understanding the mechanism that underlies spermatogenesis, which can be used as a reference for other lepidopterans.