Int. J. Dev. Biol. 56: 693 - 699 (2012)

https://doi.org/10.1387/ijdb.120049ms

Vol 56, Issue 9

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

Original Article | Published: 12 November 2012

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