Sauvadet Anne-Laure, Lynn Denis H, Roussel Erwan G, Le Panse Sophie, Bigeard Estelle, Schrével Joseph, Guillou Laure
Sorbonne Universités, Université Pierre et Marie Curie - Paris 6, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, CS90074, 29688 Roscoff Cedex, France.
Department of Integrative Biology, University of Guelph, N1G 2W1 Guelph, ON, Canada.
Eur J Protistol. 2017 Oct;61(Pt A):265-277. doi: 10.1016/j.ejop.2017.06.007. Epub 2017 Jul 11.
Microscopic and phylogenetic analyses were performed on endocommensal astome ciliates retrieved from the middle intestine of a marine cirratulid polychaete, Cirriformia tentaculata, collected in the bay of Roscoff (English Channel, Northwest French coast) and on the Southwest English coast. Three morphotypes of the astome genus Durchoniella were identified, two corresponding to described species (the type species Durchoniella brasili (Léger and Duboscq, 1904) De Puytorac, 1954 and Durchoniella legeriduboscqui De Puytorac, 1954) while a third morphotype remains undescribed. Their small subunit (SSU) rRNA gene sequences showed at least 97.2% identity and phylogenetic analyses grouped them at the base of the subclass Scuticociliatia (Oligohymenophorea), as a sister lineage to all astomes from terrestrial oligochaete annelids. Ultrastructural examination by transmission electron microscopy and fluorescence in situ hybridization analyses revealed the presence of endocytoplasmic cocci and rod-shaped bacteria surrounded by a very thin membrane. These endocytoplasmic bacteria may play a role in the association between endocommensal astome ciliates and cirratulid polychaetes inhabiting in anoxic coastal sediments.
对从一种海洋缨鳃虫多毛纲动物——触手缨鳃虫（Cirriformia tentaculata）的中肠中获取的内共生无口纤毛虫进行了显微镜和系统发育分析，该多毛纲动物采自罗斯科夫湾（英吉利海峡，法国西北海岸）以及英格兰西南海岸。鉴定出了无口属Durchoniella的三种形态型，其中两种对应已描述的物种（模式种巴西Durchoniella brasili （Léger和Duboscq，1904年）De Puytorac，1954年和Durchoniella legeriduboscqui De Puytorac，1954年），而第三种形态型尚未被描述。它们的小亚基（SSU）rRNA基因序列显示出至少97.2%的同一性，系统发育分析将它们归为盾纤亚纲（寡膜纲）基部的一个类群，作为来自陆地寡毛纲环节动物的所有无口纤毛虫的姐妹谱系。通过透射电子显微镜进行的超微结构检查和荧光原位杂交分析揭示了存在被非常薄的膜包围的胞质内球菌和杆状细菌。这些胞质内细菌可能在栖息于缺氧海岸沉积物中的内共生无口纤毛虫与缨鳃虫多毛纲动物之间的关联中发挥作用。
