Int. J. Dev. Biol. 56: 693 - 699 (2012)
doi: 10.1387/ijdb.120049ms
© UPV/EHU Press

Effect of RNAi-mediated knockdown of the Bombyx mori transformer-2 gene on the sex-specific splicing of Bmdsx pre-mRNA

Masataka G. Suzuki*,1, Keiji Suzuki1, Fugaku Aoki1 and Masahiro Ajimura2

1Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa and 2National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan

ABSTRACT In Drosophila melanogaster, transformer-2 (tra-2) is essential for female differentiation and is known to induce female-specific splicing of doublesex (dsx). The function of Bmtra-2, the Bombyx mori homolog of tra-2, on the other hand remains to be elucidated. As an initial step to learn about the biological function of Bmtra-2, we determined whether Bmtra-2 is capable of inducing the female-specific splicing of Drosophila dsx. RNAi-mediated knockdown of Bmtra-2 using Bombyx cultured cells transiently transfected with a dsx minigene revealed that Bmtra-2 can induce female-specific splicing of Drosophila dsx. To examine the role Bmtra-2 plays in regulating sex-specific splicing of Bmdsx pre-mRNA, we used an RNAi approach to reduce BmTra-2 expression in the early embryo. Embryos injected with dsRNAs or siRNAs targeted to Bmtra-2 showed no variation in the sex-specific splicing pattern of Bmdsx pre-mRNA. RNAi knockdown of Bmtra-2 in the early embryo caused abnormal testis formation. Taken together, these results indicate that Bmtra-2 is required for normal testis development, but is not involved in regulating the sex-specific splicing of Bmdsx pre-mRNA, even though it is capable of inducing the female-specific splicing of Drosophila dsx.

Keywords:

sex determination, Bombyx mori, transformer-2, alternative splicing, doublesex

*Corresponding author e-mail: gakyo@k.u-tokyo.ac.jp