Some morphologically distinguishable hypotrich ciliates share identical 18S rRNA gene sequences - taxonomic insights from a case study on Oxytricha species (Protista, Ciliophora)
Some morphologically distinguishable hypotrich ciliates share identical 18S rRNA gene sequences - taxonomic insights from a case study on Oxytricha species (Protista, Ciliophora)
复制标题
一些形态上可区分的丝毛纤毛虫具有相同的 18S rRNA 基因序列 – 来自尖毛虫属（Protista、Ciliophora）案例研究的分类学见解
DOI：
10.1093/zoolinnean/zlaa145
复制
发表时间：
2021-01-08
影响因子：
2.8
通讯作者：
Huang, Jie
中科院分区：
文献类型：
--
作者：
Fan, Xinpeng;Yao, Shunli;Huang, Jie
纤毛虫的现代分类学研究需要形态学和分子生物学数据。一个难题是如何区分形态相似的物种，而广泛使用的标记18 S rRNA基因的核苷酸差异很少。在本研究中，两种尖毛藻形态学记录使用光学和电子显微镜。测定了线粒体细胞色素c氧化酶亚基I（COI）基因和18 S-ITS 1 -5. 8 S-ITS 2 - 28 SrRNA基因片段的序列。系统发育分析的所有可用的Oxytricha granulifera相关的人口进行，以揭示这个组的内部关系。本文描述了一新种，尖毛霉Oxytricha nov.，区别于其同类有7口后腹面纤毛造成额外的分裂原基V在个体发育。虽然它们的18 SrRNA基因只有一个核苷酸的差异，但COI基因的差异高达11.8%。和近缘种，O.颗粒虫。除了一个COI核苷酸取代之外，所有COI核苷酸取代都是同义的。我们记录了18 S rRNA基因的高度保守的性质，在形态种的尖孢属。基于这些发现，我们推测O. granulifera中含有一些需要进一步鉴定的隐种或形态种，并对下毛类纤毛虫的分类学提出了新的见解。
Modern taxonomic studies of ciliated protozoa require both morphological and molecular data. One dilemma is how to distinguish morphologically similar species with few nucleotide differences in the widely used marker, the 18S rRNA gene. In the present study, two Oxytricha species were morphologically documented using light and electron microscopy. The mitochondrial cytochrome c oxidase subunit I (COI) gene and a fragment of the rRNA gene covering the 18S-ITS1-5.8S-ITS2-28S rRNA gene regions were sequenced. Phylogenetic analyses of all available Oxytricha granulifera-related populations were performed to reveal the internal relationships of this group. We described a new species, Oxytricha atypica sp. nov., distinguished from its congeners by having seven postoral ventral cirri resulting from the additional fragmentation of anlage V during ontogenesis. Although their 18S rRNA genes differ by only one nucleotide, divergence of the COI gene is as high as 11.8% between O. atypica and the closely related species, O. granulifera. All but one of the COI nucleotide substitutions were synonymous. We documented the highly conserved nature of the 18S rRNA gene in the morphospecies of Oxytricha. Based on these findings, we speculate that O. granulifera contains cryptic species or morphospecies needing further characterization, and new insights for the taxonomy of hypotrich ciliates are also discussed.