Wang Zhe, Zhou Tong, Gu Zemao
Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China.
Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China; Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan 430070, China; Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan 430070, China.
Eur J Protistol. 2017 Aug;60:50-59. doi: 10.1016/j.ejop.2017.04.002. Epub 2017 May 20.
Trichodinids are ciliated protozoan parasites or symbionts of marine and freshwater organisms. During a parasitic ciliate survey in Hubei, China, two Trichodina species, T. acutaLom, 1961 and T. hyperparasitis Chen & Hsish, 1984, were isolated from body surface of loach Misgurnus anguillicaudatus and gills of yellow catfish Pelteobagrus fulvidraco, respectively. The two species were investigated morphologically, based on silver-strained specimens, and their small subunit ribosomal RNA gene (SSU rDNA) sequences were sequenced. Morphologically, T. acuta is distinguished mainly by the acute sickle-shaped blade with well-developed sharp blade apophysis, the irregular circular granule, and the robust ray. Trichodina hyperparasitis is mainly characterized by the broad blade and the inconspicuous round ray apophysis. Phylogenetic analyses revealed that the two Trichodina species investigated were nested within a clade including several freshwater Trichodina species. This indicates that the central granule is a useful taxonomic feature, but it may not be an important phylogenetic characteristic. Histopathological analysis revealed that T. hyperparasitis firmly colonized gills, which resulted in discrete hyperplasia and injuries of the gill filaments.
车轮虫是海洋和淡水生物的纤毛原生动物寄生虫或共生体。在中国湖北进行的一次寄生纤毛虫调查中，分别从泥鳅（Misgurnus anguillicaudatus）体表和黄颡鱼（Pelteobagrus fulvidraco）鳃中分离出两种车轮虫，即尖尾车轮虫（Trichodina acuta Lom，1961）和超寄生车轮虫（Trichodina hyperparasitis Chen & Hsish，1984）。基于银染标本对这两个物种进行了形态学研究，并对其小亚基核糖体RNA基因（SSU rDNA）序列进行了测序。在形态学上，尖尾车轮虫的主要特征是具有发育良好的尖锐刀片状突出物的急性镰刀形刀片、不规则圆形颗粒和粗壮的辐线。超寄生车轮虫的主要特征是刀片宽阔且辐线突出物不明显。系统发育分析表明，所研究的两种车轮虫嵌套在一个包括几种淡水车轮虫物种的进化枝中。这表明中央颗粒是一个有用的分类学特征，但可能不是一个重要的系统发育特征。组织病理学分析表明，超寄生车轮虫牢固地定殖在鳃上，导致鳃丝离散性增生和损伤。
