Rousset F, Bouchon D, Pintureau B, Juchault P, Solignac M
CNRS-BGE, Gif sur Yvette, France.
Proc Biol Sci. 1992 Nov 23;250(1328):91-8. doi: 10.1098/rspb.1992.0135.
Rickettsia-like maternally inherited bacteria have been shown to be involved in a variety of alterations of arthropod sexuality, such as female-biased sex ratios, parthenogenesis, and sterility of crosses either between infected males and uninfected females or between infected individuals (cytoplasmic incompatibility). We have characterized several of these microorganisms through partial sequences of the small (16S) and large (23S) subunit ribosomal DNA. All the symbionts identified, which include several cytoplasmic incompatibility microorganisms, several endosymbionts of terrestrial isopods, and symbionts of two thelytokous Trichogramma wasp species, belong to a monophyletic group of related symbionts, some of which have previously been detected in several insects exhibiting cytoplasmic incompatibility. Three molecular lineages can be identified on the basis of 16S as well as 23S sequences. Although they are only known as endocellular symbionts, Wolbachia spread by horizontal transfer across host lineages as evidenced by their diversification which occurred long after that of their hosts, and by the non-congruence of the phylogenetic relationships of symbionts and their hosts. Indeed, symbionts of two different lineages have been found in the same host species, whereas closely related endosymbionts are found in distinct insect orders. Isopod endosymbionts form a separate lineage, and they can determine feminization as well as cytoplasmic incompatibility. The ability to determine cytoplasmic incompatibility, found in all lineages, is probably ancestral to this group.
类立克次氏体母系遗传细菌已被证明与节肢动物性别的多种改变有关，如偏雌性的性别比例、孤雌生殖，以及受感染雄虫与未受感染雌虫之间或受感染个体之间杂交的不育现象（细胞质不亲和）。我们通过小（16S）亚基和大（23S）亚基核糖体DNA的部分序列对其中几种微生物进行了特征分析。所有鉴定出的共生体，包括几种引起细胞质不亲和的微生物、几种陆生等足类动物的内共生体，以及两种产雌孤雌生殖赤眼蜂的共生体，都属于一个相关共生体的单系群，其中一些此前已在几种表现出细胞质不亲和的昆虫中被检测到。根据16S和23S序列可以鉴定出三个分子谱系。尽管沃尔巴克氏体仅作为细胞内共生体为人所知，但它们通过水平转移在宿主谱系间传播，这一点从它们在宿主分化很久之后才发生的多样化以及共生体与其宿主系统发育关系的不一致中得到了证明。事实上，在同一宿主物种中发现了两个不同谱系的共生体，而在不同的昆虫目中发现了亲缘关系密切的内共生体。等足类动物的内共生体形成一个单独的谱系，它们可以导致雌性化以及细胞质不亲和。在所有谱系中都发现的导致细胞质不亲和的能力可能是该类群的祖先特征。
