Program in Integrated Microbial Biodiversity, Canadian Institute for Advanced Research, Departments of Zoology and Botany, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
Protist. 2010 Jan;161(1):133-47. doi: 10.1016/j.protis.2009.09.001. Epub 2009 Oct 31.
Clautriavia is a genus of uncertain taxonomic affinity that was initially described as gliding cells with one prominent trailing flagellum and a mid-ventral groove. The genus has been classified either with euglenids on the basis of similar paramylon-like granules or with cercozoans, specifically Protaspis spp., on the basis of general similarities in cell morphology and behavior. We isolated and cultivated a novel species of Clautriavia, namely C. biflagellata n. sp., from marine sand samples collected from the west coast of Vancouver Island, Canada and characterized this isolate with high resolution microscopy (LM, SEM, and TEM) and small subunit (SSU) rDNA sequence. The gliding cells of C. biflagellata n. sp. were round to oval in outline (12-20 microm wide and 15-20 microm long), dorsoventrally flattened, and capable of engulfing other eukaryotic cells (e.g., diatoms). The cells possessed two recurrent flagella of unequal length that emerged from a subapical pit within a ventral depression: the longer prominent flagellum was about 2X the cell length; the shorter flagellum was inconspicuous and was confined to the ventral depression. Molecular phylogenetic analyses demonstrated that C. biflagellata n. sp. branched strongly within the Cercozoa, but was only distantly related to Protaspis spp. Instead, C. biflagellata n. sp. branched closely with the recently established Auranticordida clade, consisting of Auranticordis quadriverberis and Pseudopirsonia mucosa. This position was concordant with our ultrastructural data, which demonstrated several features shared by A. quadriverberis and C. biflagellata n. sp. that are not present in Protaspis spp.: (1) a dense distribution of pores on the cell surface; (2) a distinct layer of muciferous bodies immediately beneath the cell surface; (3) a robust microtubular root attached to the anterior end of the nucleus; (4) the absence of a thick cell covering; and (5) the absence of conspicuously condensed chromosomes.
Clautriavia 是一个分类地位不确定的属，最初被描述为具有一个突出的后鞭毛和中腹沟的滑行细胞。该属被归类为眼虫类，依据是类似的副淀粉粒，或者归类为裸藻类，具体为 Protaspis spp.，依据是细胞形态和行为的一般相似性。我们从加拿大温哥华岛西海岸的海洋沙样中分离并培养了一种新型的 Clautriavia 物种，即 C. biflagellata n. sp.，并通过高分辨率显微镜（LM、SEM 和 TEM）和小亚基（SSU）rDNA 序列对该分离株进行了表征。C. biflagellata n. sp. 的滑行细胞呈圆形到椭圆形（宽 12-20 微米，长 15-20 微米），背腹扁平，能够吞噬其他真核细胞（如硅藻）。细胞具有两个不等长的反复出现的鞭毛，从腹侧凹陷内的亚顶坑中伸出：较长的突出鞭毛约为细胞长度的 2 倍；较短的鞭毛不显眼，局限于腹侧凹陷内。分子系统发育分析表明，C. biflagellata n. sp. 在裸藻门内强烈分支，但与 Protaspis spp. 仅有远亲关系。相反，C. biflagellata n. sp. 与最近建立的 Auranticordida 分支密切相关，包括 Auranticordis quadriverberis 和 Pseudopirsonia mucosa。这一位置与我们的超微结构数据一致，该数据表明了 A. quadriverberis 和 C. biflagellata n. sp. 之间存在一些共同的特征，而这些特征在 Protaspis spp. 中不存在：（1）细胞表面密集分布的孔；（2）紧邻细胞表面的一层明显的粘体物质；（3）附着在前核端的坚固的微管根；（4）缺乏厚的细胞覆盖物；和（5）不存在明显浓缩的染色体。
