Graduate School of Agriculture, Tamagawa University, Machida, Tokyo, 194-8610, Japan.
Graduate School of Science and Engineering, University of Toyama, Gofuku, Toyama, 930-8555, Japan.
Sci Rep. 2021 Aug 6;11(1):15992. doi: 10.1038/s41598-021-95423-7.
The sex determination gene doublesex (dsx) encodes a transcription factor with two domains, oligomerization domain 1 (OD1) and OD2, and is present throughout insects. Sex-specific Dsx splicing isoforms regulate the transcription of target genes and trigger sex differentiation in all Holometabola examined to date. However, in some hemimetabolous insects, dsx is not spliced sexually and its sequence is less conserved. Here, to elucidate evolutionary changes in dsx in domain organisation and regulation in termites, we searched genome and/or transcriptome databases for the dsx OD1 and OD2 in seven termite species and their sister group (Cryptocercus woodroaches). Molecular phylogenetic and synteny analyses identified OD1 sequences of termites and C. punctulatus that clustered with dsx of Holometabola and regarded them as dsx orthologues. The Cryptocercus dsx orthologue containing OD2 was spliced sexually, as previously shown in other insects. However, OD2 was not found in all termite dsx orthologues. These orthologues were encoded by a single exon in three termites for which genome information is available; they were not alternatively spliced but transcribed in a male-specific manner in two examined species. Evolution of dsx regulation from sex-specific splicing to male-specific transcription may have occurred at an early stage of social evolution in termites.
性别决定基因 doublesex（dsx）编码一种具有两个结构域的转录因子，即寡聚结构域 1（OD1）和 OD2，存在于所有昆虫中。在迄今为止研究过的所有完全变态类昆虫中，特异性 Dsx 剪接异构体调节靶基因的转录，并触发性别分化。然而，在一些半变态昆虫中，dsx 不进行性别剪接，其序列的保守性较低。在这里，为了阐明白蚁中 dsx 在结构域组织和调控方面的进化变化，我们在七个白蚁物种及其姐妹群（Cryptocercus 蟑螂）的基因组和/或转录组数据库中搜索 dsx 的 OD1 和 OD2。分子系统发育和基因同线性分析鉴定出白蚁和 C. punctulatus 的 dsx OD1 序列与完全变态昆虫的 dsx 聚类，并将它们视为 dsx 同源物。以前在其他昆虫中已经表明，含有 OD2 的 Cryptocercus dsx 同源物是进行性剪接的。然而，并非所有白蚁 dsx 同源物都发现了 OD2。在三个具有基因组信息的白蚁中，这些同源物由单个外显子编码；它们没有进行选择性剪接，而是在两种被检查的物种中以雄性特异性的方式转录。dsx 调控从性别特异性剪接向雄性特异性转录的进化可能发生在白蚁社会进化的早期阶段。
