The evolution of genomic instability in the obligate endosymbionts of whiteflies.
The evolution of genomic instability in the obligate endosymbionts of whiteflies.
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DOI：
10.1093/gbe/evt044
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发表时间：
2013
影响因子：
3.3
通讯作者：
Moran NA
中科院分区：
文献类型：
--
作者：
Sloan DB;Moran NA
许多昆虫依靠与细胞内细菌的古老联系来执行必要的代谢功能。这些内共生菌在基因组结构中展示了惊人的融合例子，包括高度的结构稳定性，这不是它们自由生活的同类的典型。然而，最近测序的专性粉虱内共生体Portiera的基因组揭示了它与其他古代昆虫伴生物不同的特征，例如低基因密度和存在完全复制的序列。在这里，我们报告了波蒂埃拉基因组序列的比较分析，包括寄主物种内和寄主物种之间。在烟粉虱的一个谱系(烟粉虱)中，我们发现了波蒂拉基因组中的大规模结构多态，这种多态甚至存在于单个昆虫中。这种变异很可能是通过基因转换维持的相同重复之间的重组来调节的。来自远亲粉虱宿主(Trialurodes Vaporarium)的完整Portiera基因组序列证实了这种古老的内共生体存在广泛的基因组重排的历史。利用基于基因顺序的系统发育分析，我们发现大多数重排发生在烟粉虱的谱系中，同时核苷酸替换率增加，基因间区短串联重复序列(微卫星)的增殖，以及与DNA复制、重组和修复有关的许多广泛保守的基因的丢失。这些结果表明，重组机制的丧失不太可能是在专性内共生体基因组中普遍观察到的极端结构保守的原因，而大的重复基因间区是基因组重排的重要底物。
Many insects depend on ancient associations with intracellular bacteria to perform essential metabolic functions. These endosymbionts exhibit striking examples of convergence in genome architecture, including a high degree of structural stability that is not typical of their free-living counterparts. However, the recently sequenced genome of the obligate whitefly endosymbiont Portiera revealed features that distinguish it from other ancient insect associates, such as a low gene density and the presence of perfectly duplicated sequences. Here, we report the comparative analysis of Portiera genome sequences both within and between host species. In one whitefly lineage (Bemisia tabaci), we identify large-scale structural polymorphisms in the Portiera genome that exist even within individual insects. This variation is likely mediated by recombination across identical repeats that are maintained by gene conversion. The complete Portiera genome sequence from a distantly related whitefly host (Trialeurodes vaporarium) confirms a history of extensive genome rearrangement in this ancient endosymbiont. Using gene-order-based phylogenetic analysis, we show that the majority of rearrangements have occurred in the B. tabaci lineage, coinciding with an increase in the rate of nucleotide substitutions, a proliferation of short tandem repeats (microsatellites) in intergenic regions, and the loss of many widely conserved genes involved in DNA replication, recombination, and repair. These results indicate that the loss of recombinational machinery is unlikely to be the cause of the extreme structural conservation that is generally observed in obligate endosymbiont genomes and that large, repetitive intergenic regions are an important substrate for genomic rearrangements.
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影响因子：
--
作者：
Galens K;Orvis J;Daugherty S;Creasy HH;Angiuoli S;White O;Wortman J;Mahurkar A;Giglio MG
通讯作者：
Giglio MG
影响因子：
3.3
作者：
Kuo CH;Ochman H
通讯作者：
Ochman H
DOI：
10.1073/pnas.0906424106
发表时间：
2009-09-08
影响因子：
11.1
作者：
McCutcheon, John P.;McDonald, Bradon R.;Moran, Nancy A.
通讯作者：
Moran, Nancy A.
影响因子：
30.8
作者：
Akman, L;Yamashita, A;Aksoy, S
通讯作者：
Aksoy, S
影响因子：
3.3
作者：
McCutcheon JP;Moran NA
通讯作者：
Moran NA