Mol Biol Evol. 2010 Mar;27(3):501-5. doi: 10.1093/molbev/msp275. Epub 2009 Nov 11.
Lateral transfer of mobile DNA is a hallmark of bacteria with a free-living replicative stage; however, its significance in obligate intracellular bacteria and other heritable endosymbionts remains controversial. Comparative sequence analyses from laboratory stocks infected with Wolbachia pipientis provide some of the most compelling evidence that bacteriophage WO-B transfers laterally between infections of the same insect host. Lateral transfer between coinfections, however, has been evaluated neither in natural populations nor between closely related Wolbachia strains. Here, we analyze bacterial and phage genes from two pairs of natural sympatric field isolates, of Gryllus pennsylvanicus field crickets and of Neochlamisus bebbianae leaf beetles, to demonstrate WO-B transfers between supergroup B Wolbachia. N. bebbianae revealed the highest number of phage haplotypes yet recorded, hinting that lab lines could underestimate phage haplotype variation and lateral transfer. Finally, using the approximate age of insect host species as the maximum available time for phage transfer between host-associated bacteria, we very conservatively estimate phage WO-B transfer to occur at least once every 0-5.4 My within a host species. Increasing discoveries of mobile elements, intragenic recombination, and bacterial coinfections in host-switching obligate intracellular bacteria specify that mobile element transfer is common in these species.
移动 DNA 的横向转移是具有自由生活复制阶段的细菌的标志；然而，其在专性细胞内细菌和其他可遗传内共生体中的意义仍存在争议。来自感染沃尔巴克氏体的实验室品系的比较序列分析提供了一些最有说服力的证据，表明噬菌体 WO-B 在同一昆虫宿主的感染之间横向转移。然而，在自然种群或密切相关的沃尔巴克氏菌菌株之间，尚未评估共感染之间的横向转移。在这里，我们分析了来自两种自然共生场分离株（蟋蟀 Gryllus pennsylvanicus 和叶甲 Neochlamisus bebbianae）的细菌和噬菌体基因，以证明 B 超组沃尔巴克氏菌之间 WO-B 的转移。N. bebbianae 显示了迄今为止记录的最多的噬菌体单倍型，暗示实验室品系可能低估了噬菌体单倍型的变异和横向转移。最后，使用昆虫宿主物种的近似年龄作为宿主相关细菌之间噬菌体转移的最长可用时间，我们非常保守地估计，在宿主物种内，噬菌体 WO-B 转移至少每 0-5.4 万年发生一次。在宿主转换的专性细胞内细菌中越来越多的移动元件、基因内重组和细菌共感染的发现表明，移动元件转移在这些物种中很常见。
