Concha Carolina, Li Fang, Scott Maxwell J
Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand.
J Genet. 2010 Sep;89(3):279-85. doi: 10.1007/s12041-010-0039-5.
Genetic control of sex determination in insects has been best characterized in Drosophila melanogaster, where the master gene Sxl codes for RNA that is sex specifically spliced to produce a functional protein only in females. SXL regulates the sex-specific splicing of transformer (tra) RNA which, in turn, regulates the splicing of dsx RNA to produce functional male and female proteins. In the Australian sheep blowfly (Lucilia cuprina), the tra gene (Lctra) is required for female development and Lctra transcripts are sex-specifically spliced such that only female Lctra mRNA codes for functional protein. In males, a factor encoded by the Y-linked male determining gene is thought to prevent the female-mode of splicing of Lctra RNA. To further our understanding of the sex determination regulatory hierarchy in L. cuprina, we have isolated the dsx gene (Lcdsx) from this species. We found that the Lcdsx transcripts are sex-specifically spliced in a similar manner as their counterparts in D. melanogaster, housefly and tephritids. The LcDSX proteins are well conserved and the male form of DSX contains a motif encoded by a male-specific exon that is within the female-specific intron. This intron/exon arrangement had previously been found only in the housefly dsx gene, suggesting this may be a unique feature of dsx genes of Calyptratae species.
昆虫性别决定的遗传控制在黑腹果蝇中得到了最好的描述，其中主基因Sxl编码RNA，该RNA在性别上特异性剪接，仅在雌性中产生功能性蛋白质。SXL调节transformer（tra）RNA的性别特异性剪接，而tra RNA又调节dsx RNA的剪接，以产生功能性的雄性和雌性蛋白质。在澳大利亚羊绿蝇（Lucilia cuprina）中，tra基因（Lctra）是雌性发育所必需的，Lctra转录本在性别上特异性剪接，使得只有雌性Lctra mRNA编码功能性蛋白质。在雄性中，由Y连锁雄性决定基因编码的一个因子被认为可以阻止Lctra RNA的雌性剪接模式。为了进一步了解铜绿蝇的性别决定调控层次，我们从该物种中分离出了dsx基因（Lcdsx）。我们发现，Lcdsx转录本的性别特异性剪接方式与其在黑腹果蝇、家蝇和实蝇中的对应物相似。LcDSX蛋白高度保守，雄性形式的DSX包含一个由雄性特异性外显子编码的基序，该外显子位于雌性特异性内含子内。这种内含子/外显子排列以前只在家蝇dsx基因中发现过，这表明这可能是有瓣蝇类物种dsx基因的一个独特特征。
