Department of Biology, University of Rochester, Rochester, New York 14627, USA.
Genetics. 2011 Jan;187(1):203-15. doi: 10.1534/genetics.110.120675. Epub 2010 Oct 13.
Transferring endosymbiotic bacteria between different host species can perturb the coordinated regulation of the host and bacterial genomes. Here we use the most common maternally transmitted bacteria, Wolbachia pipientis, to test the consequences of host genetic background on infection densities and the processes underlying those changes in the parasitoid wasp genus Nasonia. Introgressing the genome of Nasonia giraulti into the infected cytoplasm of N. vitripennis causes a two-order-of-magnitude increase in bacterial loads in adults and a proliferation of the infection to somatic tissues. The host effect on W. pipientis distribution and densities is associated with a twofold decrease in densities of the temperate phage WO-B. Returning the bacteria from the new host species back to the resident host species restores the bacteria and phage to their native densities. To our knowledge, this is the first study to report a host-microbe genetic interaction that affects the densities of both W. pipientis and bacteriophage WO-B. The consequences of the increased bacterial density include a reduction in fecundity, an increase in levels of cytoplasmic incompatibility (CI), and unexpectedly, male-to-female transfer of the bacteria to uninfected females and an increased acceptance of densely infected females to interspecific mates. While paternal inheritance of the W. pipientis was not observed, the high incidence of male-to-female transfer in the introgressed background raises the possibility that paternal transmission could be more likely in hybrids where paternal leakage of other cytoplasmic elements is also known to occur. Taken together, these results establish a major change in W. pipientis densities and tissue tropism between closely related species and support a model in which phage WO, Wolbachia, and arthropods form a tripartite symbiotic association in which all three are integral to understanding the biology of this widespread endosymbiosis.
在不同宿主物种之间转移内共生细菌会破坏宿主和细菌基因组的协调调控。在这里，我们使用最常见的母系传播细菌沃尔巴克氏体（Wolbachia pipientis）来测试宿主遗传背景对寄生蜂属纳索尼亚（Nasonia）感染密度的影响以及这些变化背后的过程。将纳索尼亚长颈鹿（Nasonia giraulti）的基因组引入感染的纳索尼亚维多利亚（N. vitripennis）细胞质中，会导致细菌负荷在成虫中增加两个数量级，并使感染扩散到体细胞组织中。宿主对 W. pipientis 分布和密度的影响与温带噬菌体 WO-B 的密度降低两倍有关。将细菌从新宿主物种返回常驻宿主物种会使细菌和噬菌体恢复到其原始密度。据我们所知，这是第一项报道宿主-微生物遗传相互作用影响 W. pipientis 和噬菌体 WO-B 密度的研究。细菌密度增加的后果包括繁殖力降低、细胞质不兼容（CI）水平增加，以及出人意料的是，细菌从雄性向未感染的雌性转移，并增加了对高密度感染的雌性与同种交配的接受程度。虽然没有观察到 W. pipientis 的父系遗传，但在导入背景中雄性到雌性的高转移率表明，在其他细胞质元素也已知发生父系泄漏的杂种中，父系传递可能更有可能。综上所述，这些结果确立了在密切相关的物种之间，W. pipientis 的密度和组织嗜性发生了重大变化，并支持了一种模型，即噬菌体 WO、沃尔巴克氏体和节肢动物形成了三方共生关系，所有这三个因素对于理解这种广泛存在的内共生体的生物学都至关重要。
