Haine Eleanor R, Brondani Emilie, Hume Kevin D, Perrot-Minnot Marie-Jeanne, Gaillard Maria, Rigaud Thierry
Equipe Ecologie Evolutive, UMR CNRS 5561 Biogéosciences, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France.
Int J Parasitol. 2004 Sep;34(10):1137-46. doi: 10.1016/j.ijpara.2004.06.006.
We investigated the prevalence, transmission mode and fitness effects of infections by obligatory intracellular, microsporidian parasites in the freshwater amphipod Gammarus roeseli. We found three different microsporidia species in this host, all using transovarial (vertical) transmission. All three coexist at different prevalences in two host populations, but bi-infected individuals were rarely found, suggesting no (or very little) horizontal transmission. It is predicted that vertically-transmitted parasites may exhibit sex-specific virulence in their hosts, or they may have either positive or neutral effects on host fitness. All three species differed in their transmission efficiency and infection intensity and our data suggest that these microsporidia exert sex-specific virulence by feminising male hosts. The patterns of infection we found exhibit convergent evolution with those of another amphipod host, Gammarus duebeni. Interestingly, we found that infected females breed earlier in the reproductive season than uninfected females. This is the first study, to our knowledge, to report a positive effect of microsporidian infection on female host reproduction.
我们研究了淡水双足类动物罗氏钩虾中 obligatory intracellular、微孢子虫寄生虫感染的患病率、传播模式和适应性影响。我们在这种宿主中发现了三种不同的微孢子虫物种，它们均采用经卵（垂直）传播。这三种微孢子虫在两个宿主种群中以不同的患病率共存，但很少发现双感染个体，这表明不存在（或极少存在）水平传播。据预测，垂直传播的寄生虫可能在其宿主中表现出性别特异性毒力，或者它们可能对宿主适应性产生正向或中性影响。这三种物种在传播效率和感染强度方面存在差异，我们的数据表明，这些微孢子虫通过使雄性宿主雌性化来发挥性别特异性毒力。我们发现的感染模式与另一种双足类宿主杜氏钩虾的感染模式呈现趋同进化。有趣的是，我们发现受感染的雌性在繁殖季节比未受感染的雌性更早繁殖。据我们所知，这是第一项报道微孢子虫感染对雌性宿主繁殖有正向影响的研究。
