シロアリとその細胞内バクテリアの共生

许多节肢动物受到细胞内细菌的感染，如沃尔巴克氏菌、卡氏杆菌和立克次体。这些细菌对寄主的生态和进化有深远的影响，并进化出几种策略来增加自己的生殖适合度，有时会让寄主付出代价。并不是所有的都是寄生虫：一些进化出了与宿主的互惠关系。很少有研究大规模调查沃尔巴克氏菌的流行病学状况。本课题通过对南美白蚁500多种2392个白蚁样本的全后基因组测序，研究了白蚁的感染动态，并利用有丝分裂组和核超微结构元素(UCES)重建了白蚁的系统发育。在这个项目中，专门为白蚁设计了针对总共50616个UCE的诱饵。基于UCE的系统发育在高度支持下恢复了迄今仅通过转录组使能的数据集恢复的深层次和浅层次的关系，从而表明我们的诱饵集是可靠的和信息丰富的。发表了专门的数据库论文和相应的系统发育图。阅读图谱方法表明，1205个样本受到沃尔巴克氏菌的感染，其中两个超类群主导着南美的感染格局。在少数情况下，来自不同生活方式的单一物种的大多数样本在整个范围内都受到了感染。因此，这种亲密的共生可能解释了这些物种在生态上的成功(在准备中)。这些结果为功能基因组学开辟了道路，并揭开了白蚁--沃尔巴克氏菌共生的真正本质。

Many arthropods are infected by intracellular bacteria, such as Wolbachia, Cardinium and Rickettsia. These bacteria have profound influences on the ecology and evolution of their host and evolved several strategies to increase their own reproductive fitness, sometimes with costs for their hosts. Not all are parasites: some evolved mutualistic relationships with their hosts. Few studies investigated the epidemiological status of Wolbachia at a large scale. In this project, we investigated its infection dynamics in South American termites from whole metagenome sequencing of 2392 termite samples encompassing over 500 species.We reconstructed the termite phylogeny using mitogenomes and nuclear ultraconserved elements (UCEs). Baits targeting a total of 50616 UCEs were specifically designed for termites during this project. UCE-based phylogenies recovered with high support the deep- and shallow-level relationships recovered as yet only by transcriptome-enabled dataset, thereby demonstrating our bait set to be reliable and informative. Dedicated database paper and companion phylogenies were published.Read-mapping approach indicated that 1205 samples were infected by Wolbachia, with two supergroups dominating the South American infection landscape. In a few instances, the majority of samples from single species, with contrasted lifestyles, were infected on their whole range. Hence, such intimate symbioses might explain these species’ ecological success (in prep). These results carve the path to functional genomics and unravelling the true nature of termites-Wolbachia symbioses.