Rigaud T, Pennings P S, Juchault P
Laboratoire Génétique et Biologie des Populations de Crustacés, Université de Poitiers, UMR CNRS 6556, 40 avenue du Recteur Pineau, Poitiers Cedex, 86022, France.
J Invertebr Pathol. 2001 May;77(4):251-7. doi: 10.1006/jipa.2001.5026.
Wolbachia bacteria are intracellular parasites, vertically transmitted from mothers to offspring through the cytoplasm of the eggs. They manipulate the reproduction of their hosts to increase in frequency in host populations. In terrestrial isopods for example, Wolbachia are responsible for the full feminization of putative males, therefore increasing the proportion of females, the sex by which they are transmitted. Vertical transmission, however, is not the only means for Wolbachia propagation. Infectious (i.e., horizontal) transmission between different host species or taxa is required to explain the fact that the phylogeny of Wolbachia does not parallel that of their hosts. The aim of this study was to investigate, by experimental transinfections, whether Wolbachia strains could be successfully transferred to a different, previously uninfected isopod host. While Wolbachia survived in all the studied recipient species, vertical transmission was efficient only in cases where donor and recipient species were closely related. Even in this case, Wolbachia strains did not always keep their ability to entirely feminize their host, a deficiency that can be link to a low bacterial density in the host tissues. In addition, Wolbachia infection was associated with a decrease in host fertility, except when the bacterial strain came from the same host population as the recipient animals. This suggest that Wolbachia could be adapted to local host populations. It therefore seems that isopod Wolbachia are highly adapted to their host and can hardly infect another species of hosts. The successful infection of a given Wolbachia strain into a new isopod host species therefore probably requires a strong selection on bacterial variants.
沃尔巴克氏体细菌是细胞内寄生虫，通过卵细胞质从母体垂直传播给后代。它们操控宿主的繁殖，以在宿主种群中增加自身的频率。例如，在陆生等足动物中，沃尔巴克氏体导致假定的雄性完全雌性化，从而增加雌性的比例，而它们正是通过雌性进行传播的。然而，垂直传播并非沃尔巴克氏体传播的唯一方式。不同宿主物种或分类群之间的感染性（即水平）传播对于解释沃尔巴克氏体的系统发育与宿主的系统发育不平行这一事实是必要的。本研究的目的是通过实验性的转染来调查沃尔巴克氏体菌株是否能够成功转移到另一种先前未感染的等足动物宿主中。虽然沃尔巴克氏体在所有研究的受体物种中都能存活，但只有在供体和受体物种亲缘关系密切的情况下，垂直传播才有效。即便如此，沃尔巴克氏体菌株并不总是能保持使宿主完全雌性化的能力，这种缺陷可能与宿主组织中细菌密度低有关。此外，沃尔巴克氏体感染与宿主繁殖力下降有关，除非细菌菌株与受体动物来自同一宿主种群。这表明沃尔巴克氏体可能适应了当地的宿主种群。因此，等足动物的沃尔巴克氏体似乎高度适应其宿主，很难感染另一种宿主物种。因此，将特定的沃尔巴克氏体菌株成功感染到一种新的等足动物宿主物种中可能需要对细菌变体进行强烈的选择。
