Sex-specific splicing of the honeybee doublesex gene reveals 300 million years of evolution at the bottom of the insect sex-determination pathway
Sex-specific splicing of the honeybee doublesex gene reveals 300 million years of evolution at the bottom of the insect sex-determination pathway
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DOI：
10.1534/genetics.107.078980
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发表时间：
2007-11-01
期刊：
影响因子：
3.3
通讯作者：
Zhang, Jianzhi
中科院分区：
文献类型：
--
作者：
Cho, Soochin;Huang, Zachary Y.;Zhang, Jianzhi
性别决定机制差异很大类群。有人提出，遗传性别决定途径从途径的最后一步到第一步以相反的顺序进化。与这一假说相一致的是，果蝇性别决定级联反应中最下游的基因doublaex（dsx）决定了大多数性表型，也决定了其他双翅目和蚕蛾的性别，而上游基因在这些物种中各不相同。然而，在昆虫进化过程中，dsx是何时被募集到性别决定途径中的尚不清楚。此外，性别特异性剪接dsx，dsx决定性别，是不同的模式和机制之间的蛾和苍蝇，提出了一个有趣的问题，这些昆虫如何保持性别决定的执行者，同时允许灵活的执行手段。为了解决这些问题，在这里，我们研究了蜜蜂的dsx基因的蜜蜂，成员的最基本的血统的全变态昆虫。我们报告说，蜜蜂dsx是性别特异性剪接，它产生的苍蝇型和蛾型剪接形式，这表明使用不同的剪接形式的Dsx控制性分化存在于共同的祖先的全变态昆虫。我们的数据表明，在祖先holometabolous昆虫的女性Dsx形式是默认的和男性形式是通过抑制剪接的女性形式产生的。因此，很可能果蝇中的dsx剪接激活子系统（其中雄性形式是默认的）出现在早期双翅目进化过程中。
Sex-determination mechanisms vary greatly among taxa. It has been proposed that genetic sex-determination pathways evolve in reverse order from the final step in the pathway to the first step. Consistent with this hypothesis, doublesex (dsx), the most downstream gene in the Drosophila sex-determination cascade that determines most sexual phenotypes also determines sex in other dipterans and the silk moth, while the upstream genes vary among these species. However, it is unknown when dsx was recruited to the sex-determination pathway during insect evolution. Furthermore, sex-specific splicing of dsx, by which dsx determines sex, is different in pattern and mechanism between the moth and the fly, raising an interesting question of how these insects have kept the executor of sex determination while allowing flexibility in the means of execution. To address these questions, here we study the dsx gene of the honeybee Apis mellifera, a member of the most basal lineage of holometabolous insects. We report that honeybee dsx is sex-specifically spliced and that it produces both the fly-type and moth-type splicing forms, indicating that the use of different splicing forms of Dsx in controlling sexual differentiation was present in the common ancestor of holometabolous insects. Our data suggest that in ancestral holometabolous insects the female Dsx form is the default and the male form is generated by suppressing the splicing of the female form. Thus, it is likely that the dsx splicing activator system in flies, where the male form is the default, arose during early dipteran evolution.