Widespread genetic exchange among terrestrial bacteriophages.
Widespread genetic exchange among terrestrial bacteriophages.
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陆地噬菌体之间广泛的遗传交换。
DOI：
10.1073/pnas.0503074102
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发表时间：
2005
影响因子：
11.1
通讯作者：
Chao,Lin
中科院分区：
文献类型：
--
作者：
Silander,OlinK;Weinreich,DanielM;Wright,KevinM;O'Keefe,KaraJ;Rang,CamillaU;Turner,PaulE;Chao,Lin
噬菌体是生物圈中数量最多的实体。尽管在数量上占据优势，但人们对噬菌体群体的遗传结构知之甚少。在这里，我们提出了一项生物地理学研究，涉及来自囊病毒科分支的 25 个以前未描述的噬菌体，该群体的特征是 dsRNA 基因组分为三个片段。先前的实验室操作表明，当多种囊病毒感染单个宿主细胞时，它们会经历（i）罕见的节段内重组事件和（ii）节段之间频繁的遗传重配。分析片段内的连锁不平衡（LD），我们没有发现野生种群中片段内重组的显着证据，与（i）一致。对片段之间 LD 的广泛分析支持频繁的重配，其时间尺度类似于基因组突变率。尽管某些片段在 4 倍简并位点具有 >50% 的核苷酸分歧，但这组噬菌体中不存在 LD 与完全有性群体的预期一致。高度不相关的个体之间如此惊人的基因交换率在任何分类单元中都是前所未有的。我们根据应用于病毒的生物物种概念讨论我们的结果。
Bacteriophages are the most numerous entities in the biosphere. Despite this numerical dominance, the genetic structure of bacteriophage populations is poorly understood. Here, we present a biogeography study involving 25 previously undescribed bacteriophages from the Cystoviridae clade, a group characterized by a dsRNA genome divided into three segments. Previous laboratory manipulation has shown that, when multiple Cystoviruses infect a single host cell, they undergo (i) rare intrasegment recombination events and (ii) frequent genetic reassortment between segments. Analyzing linkage disequilibrium (LD) within segments, we find no significant evidence of intrasegment recombination in wild populations, consistent with (i). An extensive analysis of LD between segments supports frequent reassortment, on a time scale similar to the genomic mutation rate. The absence of LD within this group of phages is consistent with expectations for a completely sexual population, despite the fact that some segments have >50% nucleotide divergence at 4-fold degenerate sites. This extraordinary rate of genetic exchange between highly unrelated individuals is unprecedented in any taxa. We discuss our results in light of the biological species concept applied to viruses.