Haine E R, Motreuil S, Rigaud T
Equipe Ecologie Evolutive, UMR CNRS 5561 Biogéosciences, Université de Bourgogne, 6 boulevard Gabriel, 21000 Dijon, France.
Parasitology. 2007 Sep;134(Pt 10):1363-7. doi: 10.1017/S0031182007002715. Epub 2007 Apr 20.
SUMMARYVertically transmitted parasites may have positive, neutral or negative effects on host fitness, and are also predicted to exhibit sex-specific virulence to increase the proportion or fitness of the transmitting sex. We investigated these predictions in a study on the survival and sex ratio of offspring of the amphipod Gammarus roeseli from females infected by the vertically transmitted microsporidia Nosema granulosis. We found, to our knowledge, the first evidence for a positive relationship between N. granulosis infection and host survival. Infection was associated with sex ratio distortion, not by male-killing, but probably by parasite-induced feminization of putative G. roeseli males. This microsporidia also feminizes another amphipod host, Gammarus duebeni, which is phylogenetically and biogeographically distant from G. roeseli. Our study suggests that the reproductive system of gammarids is easily exploited by these vertically-transmitted parasites, although the effects of infections on host fitness may depend on specific host-parasite species interactions.
摘要
垂直传播的寄生虫可能对宿主适应性产生积极、中性或负面影响，并且预计还会表现出性别特异性毒力，以提高传播性别的比例或适应性。我们在一项关于感染垂直传播的微孢子虫 Nosema granulosis 的雌性罗氏钩虾后代的存活和性别比例的研究中，对这些预测进行了调查。据我们所知，我们首次发现了 Nosema granulosis 感染与宿主存活之间存在正相关的证据。感染与性别比例扭曲有关，不是通过杀雄，而是可能通过寄生虫诱导假定的罗氏钩虾雄性雌性化。这种微孢子虫还会使另一种钩虾宿主杜氏钩虾雌性化，杜氏钩虾在系统发育和生物地理学上与罗氏钩虾相距甚远。我们的研究表明，尽管感染对宿主适应性的影响可能取决于特定的宿主 - 寄生虫物种相互作用，但钩虾的生殖系统很容易被这些垂直传播的寄生虫利用。
