Department of Invertebrate Zoology, Faculty of Biology, St. Petersburg State University, Universitetskaja nab. 7/9, 199034, St. Petersburg, Russia; Laboratory of Cellular and Molecular Protistology, Zoological Institute RAS, Universitetskaja nab. 1,199034, St. Petersburg, Russia.
Department of Invertebrate Zoology, Faculty of Biology, St. Petersburg State University, Universitetskaja nab. 7/9, 199034, St. Petersburg, Russia.
Eur J Protistol. 2020 Apr;73:125686. doi: 10.1016/j.ejop.2020.125686. Epub 2020 Feb 7.
The life cycle of the centrohelid heliozoan Raphidiophrys heterophryoidea Zlatogursky, 2012 was studied with light and electron microscopy in clonal cultures from the type locality. The alternation of two types of trophozoites, having contrastingly different morphology, was observed. Type 1 trophozoites morphology matched the original description. Type 2 trophozoites tended to form colonies usually of 6-8 individuals, connected with cytoplasmic bridges and their cell size was noticeably bigger, namely 43-45 μm compared to 24.5 μm on average in type 1 trophozoites. Some colonies were forming stalks composed of three or four axopodia covered with scales. Spicules were lacking completely, while plate-scales differed from those of type 1 trophozoites: they had oblong-elliptical shape, larger (5.9-14.1 × 2.4-5.8 μm) size, non-branching septa always reaching scale centre, solid upper plate. The conspecificity of the two trophozoite types was confirmed with the comparison of SSU rDNA gene sequence data. Both types of trophozoites were capable of encystment and excysted individuals always were type 1 trophozoites. A new type of cyst-scales (cup-scales) was described. Transitions between cysts and the two trophozoites types were documented. The diagnosis of R. heterophryoidea was improved accordingly. The possible functions, driving forces, and taxonomic consequences of the polymorphism were discussed.
采用光镜和电镜技术，对产自模式产地的克隆培养物中的旋口虫目旋口虫科异口旋口虫（Raphidiophrys heterophryoidea）的生活史进行了研究。观察到两种形态明显不同的营养体类型的交替。1 型营养体的形态与原始描述相符。2 型营养体倾向于形成通常由 6-8 个个体组成的群体，通过细胞质桥连接，其细胞大小明显较大，即 43-45 μm，而 1 型营养体的平均大小为 24.5 μm。一些群体形成由三个或四个具刺毛的轴足组成的柄，完全缺乏小刺，而板状鳞片与 1 型营养体的不同：它们呈长椭圆形，较大（5.9-14.1×2.4-5.8 μm），不分枝的隔片始终到达鳞片中心，上板为实心。通过比较 SSU rDNA 基因序列数据，确认了这两种营养体类型的同物异性。两种营养体类型都能够形成孢囊，而逸出的个体始终是 1 型营养体。描述了一种新的孢囊鳞片（杯状鳞片）。记录了孢囊与两种营养体类型之间的转变。相应地改进了异口旋口虫的诊断。讨论了多态性的可能功能、驱动力和分类学后果。
