The University of Queensland, School of Biological Sciences, Brisbane, Queensland 4072, Australia; CSIRO Agriculture and Food, Integrated Sustainable Aquaculture Production, Bribie Island Research Centre, 144 North Street, Woorim, Queensland 4507, Australia.
Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic.
Eur J Protistol. 2019 Feb;67:27-45. doi: 10.1016/j.ejop.2018.10.003. Epub 2018 Oct 29.
Neoparamoeba perurans is the aetiological agent of amoebic gill disease (AGD) in salmonids, however multiple other amoeba species colonise the gills and their role in AGD is unknown. Taxonomic assessments of these accompanying amoebae on AGD-affected salmon have previously been based on gross morphology alone. The aim of the present study was to document the diversity of amoebae colonising the gills of AGD-affected farmed Atlantic salmon using a combination of morphological and sequence-based taxonomic methods. Amoebae were characterised morphologically via light microscopy and transmission electron microscopy, and by phylogenetic analyses based on the 18S rRNA gene and cytochrome oxidase subunit I (COI) gene. In addition to N. perurans, 11 other amoebozoans were isolated from the gills, and were classified within the genera Neoparamoeba, Paramoeba, Vexillifera, Pseudoparamoeba, Vannella and Nolandella. In some cases, such as Paramoeba eilhardi, this is the first time this species has been isolated from the gills of teleost fish. Furthermore, sequencing of both the 18S rRNA and COI gene revealed significant genetic variation within genera. We highlight that there is a far greater diversity of amoebae colonising AGD-affected gills than previously established.
新内变形虫是鲑鱼变形虫病（AGD）的病原体，然而，还有多种其他变形虫物种定植在鱼鳃上，其在 AGD 中的作用尚不清楚。以前对受 AGD 影响的鲑鱼中这些伴随变形虫的分类评估仅基于宏观形态。本研究的目的是使用形态学和基于序列的分类方法相结合，记录定植在 AGD 患病养殖大西洋鲑鱼鳃上的变形虫的多样性。通过光学显微镜和透射电子显微镜以及基于 18S rRNA 基因和细胞色素氧化酶亚基 I（COI）基因的系统发育分析对变形虫进行了形态特征描述。除了新内变形虫外，还从鱼鳃中分离出 11 种其他变形虫，它们被分类在新内变形虫属、变形虫属、帆形变形虫属、拟内变形虫属、Vannella 和 Nolandella 属中。在某些情况下，如 Paramoeba eilhardi，这是该物种首次从硬骨鱼的鳃中分离出来。此外，18S rRNA 和 COI 基因的测序揭示了属内存在显著的遗传变异。我们强调，定植在 AGD 患病鱼鳃上的变形虫的多样性远远超过以前的认识。
