Abstract:
Wolbachia are obligate intracellular alphaproteobacteria that enhance their spreading by altering the reproductive mechanisms of several invertebrates. Among the reproductive alterations, Wolbachia also causes cytoplasmic incompatibility that leads to embryo death when infected males are crossed with uninfected females, thus selecting infected females. However, the presence of Wolbachia has important fitness costs and infected Drosophila simulans males produce less sperm than their uninfected counterparts. Such sperm suffer, indeed, of some structural alterations that hinder their proper function. We took advantage of the fact that several sperm have abnormal distal regions of the tail, in which the plasma membrane is broken and the axonemal components splayed, making the ultrastructural aspects clearly observable. We found that axoneme reduction in the distal region of the sperm does not follow a unique pattern as observed in other insects, but occurs by losing accessory tubules or peripheral doublets. The axonemal tubules contain distinct coaxial ring-like structures that are still observed after axoneme fragmentation and form large clusters of several units.
摘要:
Wolbachia是专性的细胞内α变形菌,通过改变几种无脊椎动物的生殖机制来增强其传播。在生殖改变中,Wolbachia还导致细胞质不相容,当受感染的雄性与未感染的雌性杂交时,导致胚胎死亡,从而选择受感染的女性。然而,Wolbachia的存在具有重要的健身成本,受感染的果蝇模拟雄性比未感染的果蝇产生更少的精子。这样的精子受苦,的确,一些阻碍其正常功能的结构改变。我们利用了这样一个事实,即几个精子的尾巴远端区域异常,其中质膜破裂,轴突成分张开,使超微结构方面清晰可见。我们发现,精子远端区域的轴突减少并不像在其他昆虫中观察到的那样遵循独特的模式,而是通过失去附属小管或外周双峰而发生的。轴突小管包含不同的同轴环状结构,在轴突分裂后仍然可以观察到,并形成几个单元的大簇。