The spread of a transposon insertion in Rec8 is associated with obligate asexuality in Daphnia
The spread of a transposon insertion in Rec8 is associated with obligate asexuality in Daphnia
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DOI：
10.1073/pnas.1119667109
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发表时间：
2012-01-17
影响因子：
11.1
通讯作者：
Zolan, Miriam E.
中科院分区：
文献类型：
--
作者：
Eads, Brian D.;Tsuchiya, Dai;Zolan, Miriam E.
虽然从有性生殖到无性生殖的转变被认为具有重要的进化后果，但人们对这些变化的机械基础知之甚少。周期性孤雌生殖蚤是一个强大的模型，以解决这些问题，因为女性有限的减数分裂抑制可以通过男性传递到性个体，提供了遗传解剖的特点的机会。先前的研究确定了区分专性无性雌性与其性对应物的基因组区域，并且在一个这样的区域内的候选基因，编码减数分裂粘附素Rec8，是本次调查的主题。地方蚤属基因组包含三个Rec8基因座，所有这些基因座都具有相当的多态性。然而，在其中一个位点，所有专性无性克隆都携带一个等位基因，该等位基因含有一个相同的上游插入的转座因子以及一个移码突变，这两者在有性谱系中完全不存在。插入等位基因在所有无性系中的低水平变异表明，该元件可能处于通过物种传播的过程中，Rec8功能的废除或修改可能是负责将减数分裂生殖谱系转换为专性无性系。
Although transitions from sexual to asexual reproduction are thought to have important evolutionary consequences, little is known about the mechanistic underpinnings of these changes. The cyclical parthenogen Daphnia pulex is a powerful model in which to address these issues because female-limited meiosis suppression can be transmitted to sexual individuals via males, providing the opportunity for genetic dissection of the trait. A previous study identified genomic regions differentiating obligately asexual females from their sexual counterparts, and a candidate gene within one such region, encoding the meiotic cohesin Rec8, is the subject of this investigation. The D. pulex genome contains three Rec8 loci, all of which are quite polymorphic. However, at one of the loci, all obligately asexual clones carry an allele containing an identical upstream insertion of a transposable element as well as a frameshift mutation, both of which are completely absent from sexual lineages. The low level of variation within the insertion allele across all asexual lineages suggests that this element may be in the process of spreading through the species, and abrogation or modification of Rec8 function is possibly responsible for converting meiotically reproducing lineages into obligate asexuals.