Segmental Duplication Implicated in the Genesis of Inversion 2Rj of Anopheles gambiae
Segmental Duplication Implicated in the Genesis of Inversion 2Rj of Anopheles gambiae
复制标题
DOI：
10.1371/journal.pone.0000849
复制
发表时间：
2007-09-05
期刊：
影响因子：
3.7
通讯作者：
Besansky, Nora J.
中科院分区：
文献类型：
--
作者：
Coulibaly, Mamadou B.;Lobo, Neil F.;Besansky, Nora J.
疟疾媒介冈比亚按蚊保持着高度的倒位多态，这有助于它在整个热带非洲利用不同的生态环境。反转断点的分子特征是理解产生和维持反转的过程的第一步。在这里，我们重点研究倒位2RJ，因为它与AN的配对交配的Bamako染色体形式有关。冈比亚，其独特的繁殖地是马里和几内亚尼日尔河边的岩石池塘。2RJ的测序和计算分析显示，在两个断裂点之间有相同的14.6kb插入，发生在预测基因附近，但不在预测基因内。每个插入由5.3kb的末端倒置重复臂组成，由4kb的间隔物隔开。插入片段缺乏编码能力，并且由包括I类和II类转座元件的重复序列的降解残基组成。因为它们的大尺寸和拼接组成，以及在AN中没有发现这些插入物的其他实例。冈比亚的基因组中，它们似乎不是转座元件。插入在两个2RJ断点连接处的14.6kb模块代表低拷贝重复(LCR，也称为节段性复制)，这些低拷贝重复与2RJ最近(类似于0.4n(E)代)的起源密切相关。LCR有助于进一步的基因组不稳定，正如野外分离株中2RJ近端断裂点的不精确切除事件所证明的那样。
The malaria vector Anopheles gambiae maintains high levels of inversion polymorphism that facilitate its exploitation of diverse ecological settings across tropical Africa. Molecular characterization of inversion breakpoints is a first step toward understanding the processes that generate and maintain inversions. Here we focused on inversion 2Rj because of its association with the assortatively mating Bamako chromosomal form of An. gambiae, whose distinctive breeding sites are rock pools beside the Niger River in Mali and Guinea. Sequence and computational analysis of 2Rj revealed the same 14.6 kb insertion between both breakpoints, which occurred near but not within predicted genes. Each insertion consists of 5.3 kb terminal inverted repeat arms separated by a 4 kb spacer. The insertions lack coding capacity, and are comprised of degraded remnants of repetitive sequences including class I and II transposable elements. Because of their large size and patchwork composition, and as no other instances of these insertions were identified in the An. gambiae genome, they do not appear to be transposable elements. The 14.6 kb modules inserted at both 2Rj breakpoint junctions represent low copy repeats (LCRs, also called segmental duplications) that are strongly implicated in the recent (similar to 0.4N(e) generations) origin of 2Rj. The LCRs contribute to further genome instability, as demonstrated by an imprecise excision event at the proximal breakpoint of 2Rj in field isolates.