Department of Oceanography, Research Institute for Dok-do and Ulleung-do Island and Kyungpook Institute of Oceanography, School of Earth System Sciences, Kyungpook National University, Daegu, Korea.
J Eukaryot Microbiol. 2019 Mar;66(2):221-231. doi: 10.1111/jeu.12664. Epub 2018 Jul 9.
Halophilic protozoa are independently scattered across the molecular phylogeny of eukaryotes; most of which are assigned to Heterolobosea. Here, we isolated a biflagellate from a hypersaline water of 342‰ salinity. This isolate shared several morphological features with typical halophilic heterolobosean flagellates. In addition, molecular phylogenetic trees of the 18S rRNA gene sequences clearly indicated flagellate is a heterolobosean species closely related to the halophilic Tulamoebidae. However, the flagellate was not accommodated to any described genus. Cells were ovoid-shaped, and no amoebae were observed. The two unequal flagella beat heterodynamically. An ear-like bulge at the margin of a cytostomal groove was observed. Flagellates could grow at 100-200‰ salinity, suggesting an obligately halophilic species. Currently, it appears that the new halophilic Aurem hypersalina forms a strong clade with Tulamoebidae, and is sister to the Tulamoebidae, indicating that this new clade is composed almost entirely of obligate halophilic taxa. Thus, A. hypersalina and the Tulamoebidae clade currently represent a unique adaptive radiation of halophilic eukaryotes.
嗜盐原生动物独立分散在真核生物的分子系统发育中；其中大多数被归为异变形目。在这里，我们从盐度为 342‰的高盐水中分离出一种双鞭毛原生动物。该分离株与典型的嗜盐异变形鞭毛虫具有一些相似的形态特征。此外，18S rRNA 基因序列的分子系统发育树清楚地表明，鞭毛虫是一种与嗜盐滴虫科密切相关的异变形目物种。然而，这种鞭毛虫不能归入任何已描述的属。细胞呈卵圆形，没有观察到变形虫。两个不等长的鞭毛呈异动态摆动。在口沟边缘观察到一个耳状隆起。鞭毛虫可以在 100-200‰的盐度下生长，表明它是一种专性嗜盐物种。目前，嗜盐性 Aurem hypersalina 似乎与滴虫科形成了一个强大的分支，与滴虫科是姐妹关系，这表明这个新分支几乎完全由专性嗜盐分类群组成。因此，A. hypersalina 和滴虫科分支目前代表了一个独特的嗜盐真核生物的适应性辐射。
