文章基本信息

标题：Description of a new species of Tetmemena (Ciliophora, Oxytrichidae) using classical and molecular markers
本地全文：下载
作者：Renu Gupta ; Jeeva Susan Abraham ; S. Sripoorna 等
期刊名称：Journal of King Saud University - Science
印刷版ISSN：1018-3647
出版年度：2020
卷号：32
期号：4
页码：2316-2328
DOI：10.1016/j.jksus.2020.03.009
语种：English
出版社：Elsevier
摘要：AbstractTetmemena saprain. sp. was isolated from fresh-water samples collected from Okhla Bird Sanctuary, Delhi, India and described based on its morphology, morphogenesis and molecular markers, namely the small-subunit (SSU) rRNA gene and internal transcribed spacers (ITS1-5.8S-ITS2). The morphological features ofT. saprain. sp. are as follows: colourless; rigid body with no cortical granules; water expelling vesicle about 15 µm in size, located below the adoral zone of membranelles near the left body margin; body size about 125–140 × 50–60 μm in live and about 100 × 45 μm in protargol preparations, with body length : width ratio should be 2:1; undulating membranes in aStylonychia-pattern; adoral zone about 44 μm in length with (on average) 45 adoral membranelles; 18 frontal-ventral-transverse cirri; one right and one left marginal row; six dorsal rows including two dorsomarginals, of which the fourth row is shortened anteriorly; three caudal cirri which are not equidistant; two macronuclear nodules; 2–4 micronuclei. A detailed morphogenetic study revealed the oral primordium to originate near the leftmost transverse cirrus, and the involvement of five parental cirri (three frontals and two ventrals) in the formation of streaks I–VI for the proter and opisthe. The genetic distance betweenT. saprain. sp. and its congenersT. pustulataandT.vorax(S. vorax)varied from between 1% and 2% in the SSU rRNA gene and 1% and 6% in the ITS1-5.8S-ITS2 sequence. The secondary structures of the ITS1 and ITS2 RNA transcripts of four different species of genusTetmemena(T. saprain. sp.,T. pustulata,T. voraxandT.bifaria) were also compared, revealing that the ITS1 region was more variable than ITS2. The morphological and morphogenetic characterisation, and phylogenetic analyses based on the molecular markers, confirm that the present species is a distinct species of the genusTetmemenabelonging to the subfamily Stylonychinae.This study also reveals that the macronuclear ITS region can be a suitable candidate for species identification.
关键词：Oxytrichid ciliates;New species;Ciliature;Taxonomy;SSU rRNA gene;Molecular markers