Terry R S, Dunn A M, Smith J E
Department of Biology, University of Leeds, UK.
Parasitology. 1997 Aug;115 ( Pt 2):157-63. doi: 10.1017/s0031182097001236.
The cellular distribution of a vertically transmitted, feminizing microsporidian was followed in its host Gammarus duebeni. In adult females the parasite was restricted to gonadal tissue, in particular primary and secondary follicle cells. Spores were diplokaryotic with a thin spore wall and a short polar filament, characteristics typical of 'early' spores involved in autoinfection. The diplokaryotic life-cycle, absence of spore groupings and of a pansporoblast membrane typify the genus Nosema. However, the unusual globular polaroplast of the spore and restriction of this stage to host ovarian tissue have not previously been described in Nosema. Sporogony occurred only in follicle cells adjacent to developing oocytes and was in synchrony with the process of vitellogenesis. Oocytes were infected after formation of intracellular connections with follicle cells but harboured only vegetative stages of the parasite. Parasites were associated with the perinuclear cytoplasm and, in developing embryos, segregated to daughter cells along the axis of the spindle. In juvenile animals there was no evidence of pathology linked with feminization and the parasite was found at low density in cells under the cuticle. The parasite is highly adapted to transovarial transmission with an efficient mechanism of oocyte infection and no evidence of pathology.
对一种垂直传播的、具有雌性化作用的微孢子虫在其宿主杜氏钩虾中的细胞分布情况进行了追踪研究。在成年雌性个体中，该寄生虫局限于性腺组织，尤其是初级和次级卵泡细胞。孢子为双核，具薄孢子壁和短极丝，这些是参与自身感染的“早期”孢子的典型特征。双核生命周期、不存在孢子聚集以及无全成孢子膜是 Nosema 属的典型特征。然而，该孢子不同寻常的球状极质体以及此阶段局限于宿主卵巢组织的情况，此前在 Nosema 属中尚未有过描述。孢子生殖仅发生在与发育中卵母细胞相邻的卵泡细胞中，且与卵黄发生过程同步。卵母细胞在与卵泡细胞形成细胞内连接后被感染，但仅含有寄生虫的营养阶段。寄生虫与核周细胞质相关联，在发育中的胚胎中，沿纺锤体轴分离到子细胞中。在幼年动物中，没有与雌性化相关的病理迹象，且在表皮下细胞中发现该寄生虫的密度较低。该寄生虫高度适应经卵传递，具有高效的卵母细胞感染机制且无病理迹象。
