秀丽隐杆线虫雌雄同体趋同进化中的遗传灵活性。

Genetic flexibility in the convergent evolution of hermaphroditism in Caenorhabditis nematodes.

作者信息

Hill Robin Cook, de Carvalho Carlos Egydio, Salogiannis John, Schlager Benjamin, Pilgrim Dave, Haag Eric S

机构信息

Department of Biology, University of Maryland, College Park, 20742, USA.

出版信息

Dev Cell. 2006 Apr;10(4):531-8. doi: 10.1016/j.devcel.2006.02.002.

DOI:10.1016/j.devcel.2006.02.002

PMID:16580997

Abstract

The self-fertile hermaphrodites of C. elegans and C. briggsae evolved from female ancestors by acquiring limited spermatogenesis. Initiation of C. elegans hermaphrodite spermatogenesis requires germline translational repression of the female-promoting gene tra-2, which allows derepression of the three male-promoting fem genes. Cessation of hermaphrodite spermatogenesis requires fem-3 translational repression. We show that C. briggsae requires neither fem-2 nor fem-3 for hermaphrodite development, and that XO Cb-fem-2/3 animals are transformed into hermaphrodites, not females as in C. elegans. Exhaustive screens for Cb-tra-2 suppressors identified another 75 fem-like mutants, but all are self-fertile hermaphrodites rather than females. Control of hermaphrodite spermatogenesis therefore acts downstream of the fem genes in C. briggsae. The outwardly similar hermaphrodites of C. elegans and C. briggsae thus achieve self-fertility via intervention at different points in the core sex determination pathway. These findings are consistent with convergent evolution of hermaphroditism, which is marked by considerable developmental genetic flexibility.

摘要

秀丽隐杆线虫（C. elegans）和嗜热栖热放线菌（C. briggsae）的自交能育雌雄同体是由雌性祖先通过获得有限的精子发生能力进化而来的。秀丽隐杆线虫雌雄同体精子发生的起始需要对促进雌性发育的基因tra-2进行生殖系翻译抑制，这使得三个促进雄性发育的fem基因得以去抑制。雌雄同体精子发生的停止需要对fem-3进行翻译抑制。我们发现，嗜热栖热放线菌的雌雄同体发育既不需要fem-2也不需要fem-3，并且XO Cb-fem-2/3动物会转变为雌雄同体，而不像秀丽隐杆线虫那样转变为雌性。对Cb-tra-2抑制子进行全面筛选又鉴定出了另外75个类似fem的突变体，但所有这些突变体都是自交能育的雌雄同体，而非雌性。因此，嗜热栖热放线菌中雌雄同体精子发生的调控作用于fem基因的下游。秀丽隐杆线虫和嗜热栖热放线菌外观相似的雌雄同体通过在核心性别决定途径的不同点进行干预来实现自交能育。这些发现与雌雄同体的趋同进化一致，其特点是具有相当大的发育遗传灵活性。