Thongsaiklaing Thanaset, Nipitwattanaphon Mingkwan, Ngernsiri Lertluk
Center of Agricultural Biotechnology, Kasetsart University, Nakon Pathom, Thailand.
Center of Excellence on Agricultural Biotechnology: (AG-BIO/PERDO-CHE), Bangkok, Thailand.
Insect Mol Biol. 2018 Dec;27(6):766-779. doi: 10.1111/imb.12517. Epub 2018 Aug 14.
The insect transformer2 (tra2) gene has a prevalent role in cooperating with the sex-determining gene transformer (tra) to direct female differentiation. Here, we report the identification and characterization of Btau-tra2, the tra2 orthologue of the pumpkin fruit fly, Bactrocera tau, an invasive agricultural pest. The Btau-tra2 gene produces three transcript variants. However, only two transcripts can be examined; one is present at all developmental stages in the soma and germline of both sexes and the other one is specific to the embryo and the germline. Knocking down the function of Btau-tra2 produced a male-biased sex ratio and some intersexes. Consistent with a role in sex determination, the obtained intersexual and male sterility phenotypes express a mix of male and female splice variants of the tra and doublesex (dsx) orthologues, indicating that Btau-tra2 has a conserved splicing regulatory function and acts together with/upstream of tra and dsx. In addition, some males obtained from the knock down are fertile but their fertilities are extremely reduced. Moreover, almost all surviving RNA interference (RNAi) males harbour testes having some defects in their external morphologies. Most notably, the body size of a few surviving RNAi flies was two-to threefold increased with respect to the normal size. Our findings suggest that Btau-tra2 is involved in male fertility and may also have an unprecedented role in body size control besides its conserved role in sex determination.
昆虫transformer2（tra2）基因在与性别决定基因transformer（tra）协同作用以指导雌性分化方面发挥着普遍作用。在此，我们报告了南瓜实蝇（一种入侵性农业害虫）tra2直系同源基因Btau-tra2的鉴定和特征。Btau-tra2基因产生三种转录变体。然而，只能检测到两种转录本；一种在两性的体细胞和生殖系的所有发育阶段都存在，另一种则特异于胚胎和生殖系。敲低Btau-tra2的功能导致雄性偏向的性别比例和一些雌雄间性个体。与在性别决定中的作用一致，所获得的雌雄间性和雄性不育表型表达了tra和doublesex（dsx）直系同源基因的雄性和雌性剪接变体的混合，表明Btau-tra2具有保守的剪接调节功能，并与tra和dsx一起作用/在其上游起作用。此外，从敲低实验中获得的一些雄性是可育的，但它们的生育力极度降低。而且，几乎所有存活的RNA干扰（RNAi）雄性的睾丸在外部形态上都有一些缺陷。最显著的是，一些存活的RNAi果蝇的体型相对于正常大小增加了两到三倍。我们的研究结果表明，Btau-tra2参与雄性生育力，并且除了在性别决定中的保守作用外，可能在体型控制中也具有前所未有的作用。
