Tang Fahui, Zhang Yong, Zhao Yuanjun
Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, Chongqing, 401331, China.
J Eukaryot Microbiol. 2017 Jan;64(1):45-55. doi: 10.1111/jeu.12335. Epub 2016 Jul 8.
It is difficult to differentiate similar trichodinids solely based on morphological examination, thus other identification methods, such as molecular identification, are necessary for identification. One mobilid ciliate named Trichodina pseudoheterodentata sp. n. was isolated from the gills of channel catfish, Ictalurus punctatus, in Chongqing, China. In the present study, its SSU rDNA was sequenced for the first time. Based on the results from both morphological identification and SSU rDNA sequencing, the new species was identified and compared with similar species. The morphological analysis revealed that T. pseudoheterodentata is a large Trichodina species (cell diameter 73.0-82.5 μm) and possesses robust denticles with broad blades and well-developed blade connections. Characterization of its primary and secondary SSU rDNA structures indicated that T. pseudoheterodentata was distinctly different from congeneric species in H12, H15, E10_1, and V4 regions. Phylogenetic analysis revealed that the genetic distances among the new species and similar species reached interspecific levels, furthermore, the phylogenetic study also validated the identification of T. pseudoheterodentata and its placement in the genus Trichodina.
仅基于形态学检查很难区分相似的车轮虫，因此需要其他鉴定方法，如分子鉴定来进行识别。一种名为拟异齿车轮虫（Trichodina pseudoheterodentata sp. n.）的动基片纲纤毛虫从中国重庆的斑点叉尾鮰（Ictalurus punctatus）鳃中分离得到。在本研究中，首次对其小亚基核糖体DNA（SSU rDNA）进行了测序。基于形态学鉴定和SSU rDNA测序结果，对该新物种进行了鉴定并与相似物种进行了比较。形态学分析表明，拟异齿车轮虫是一种大型车轮虫物种（细胞直径73.0 - 82.5μm），具有粗壮的齿体，其齿片宽阔且齿片连接发达。对其一级和二级SSU rDNA结构的特征分析表明，拟异齿车轮虫在H12、H15、E10_1和V4区域与同属物种明显不同。系统发育分析表明，新物种与相似物种之间的遗传距离达到种间水平，此外，系统发育研究也验证了拟异齿车轮虫的鉴定及其在车轮虫属中的分类地位。
