摘要
Wolbachia是广泛分布在节肢动物生殖组织中的一类细胞质遗传的细菌。它们能通过多种机制调节寄主的生殖 ,包括诱导细胞质不亲和、孤雌生殖和遗传上的雄性雌性化。目前对这些微生物的研究已取得了可喜的进展。通过主要综述Wolbachia的分布、功能、系统发育、多样性及时空动态 ,也讨论了将来的研究方向。
We reviewed the distribution, functions, phylogeny, diversity, and spatial and temporal variation of Wolbachia. Wolbachia are cytoplasmically inherited bacteria and widely found in reproductive tissues of arthropods. Systematic surveys of Wolbachia distribution and diversity are now possible using PCR\|based methodologies. The 16S rDNA and ftsZ studies have provided a number of useful molecular tools for such surveys. A survey of Panamanian rainforest insects and the members of two temperate host\|parasitoid food webs detected Wolbachia strains in 18\^6% of species sampled, with a corresponding figure of 17\^9% for Hymenoptera. So far, Wolbachia has been detected in 31 genera and 70 species of parasitic Hymenoptera, as well as in three dipteran parasitoids. Estimates of prevalence in different parasitoid taxa or assemblages yield an overall mean of 26%. However, it should be borne in mind that these surveys inevitably underestimate the number of species that harbor Wolbachia. The number of known infected species has been increasing rapidly each year but the limits of distribution for this bacterial group are yet unknown. Wolbachia have evolved various mechanisms for manipulating reproduction of their hosts to enhance their transmission, including induction of reproductive incompatibility, parthenogenesis, and genetic male feminization. Wolbachia \|induced cytoplasmic incompatibility (CI) is a reproductive incompatibility between sperm and egg. They are chiefly transmitted in eggs. CI takes two forms, unidirectional and bidirectional. But the biochemical mechanisms of CI still remain unknown. The presence of CI was confirmed by mating experiments with the small brown planthoppers, Laodelphax striatellus Fallen from six locations in China and one from Japan. A number of factors including bacterial strain, host genotype and bacterial density can interact with each other in complex ways to influence strength and direction of CI. Parthenogensis induction (PI)\| Wolbachia cause thelytoky in arrhenotokous parasitoids by generating diploid(rather than haploid) unfertilized wasp eggs. It occurs because in the first mitotic division the chromosomes condense properly in prophase but fail to segregate in metaphase, resulting in diploidization of the nucleus. Antibiotic curing and heat treatment (>30℃) can reverse to male production with elimination of the bacteria. And the relative fitness of infected and unifected hosts is important to the population dynamics of PI Wolbachia. Female sex determination in the woodlouse Armadillidium vulgare is frequently under the control of feminizing parasitic sex factors (PSF), one of these PSF is intracytoplasmic Wolbachia bacteria (F), while the other (f) is suspected of being an F\|bacteral DNA sequence unstably intergrated into the host genome. In most wild populations harboring PSF, all individuals are genetic males (ZZ), and female phenotypes occur only due to the presence of PSF which overrides the male determinant carried by the Z chromosome. There is a conflict between these PSF and a dominant autosomal masculinizing gene (M) on phenotypes. The M gene is able to override the feminizing effect of the f sex factor but it can not restore male sex when competing with the F bacteria. Maximum parsimony analysis of the nearly full\|length sequence of Wolbachia pipientis from Culex pipiens tissue, aligned with representative eubacteria, revealed that W.pipientis is situated in the α\|subdivision of the Proteobacteria. The genus Wolbachia as currently defined is polyphyletic. From the comparison of the sequence of W.persica and W.pipientis, it is clear that the two bacteria are not closely related. Wolbachia persica, the only other member of the genus Wolbachia, belongs to the γ\|subdivision of the Proteobacteria. The ftsZ study for 38 different Wolbachia strains from 33 host species uncovered considerable variation among Wolbachia strains. There are two major subdivisions, A and B. At the same time, t
出处
《生态学报》
CAS
CSCD
北大核心
2002年第3期409-419,共11页
Acta Ecologica Sinica
基金
国家自然科学基金 ( 396 30 2 0 0 )
