Choudhary Kirti, Tripathi Amit, Pandey Keshava C, Agrawal Nirupama
Department of Zoology, University of Lucknow, Lucknow 226007, Uttar Pradesh, India.
Department of Zoology, University of Lucknow, Lucknow 226007, Uttar Pradesh, India.
Parasitol Int. 2017 Oct;66(5):652-659. doi: 10.1016/j.parint.2017.06.007. Epub 2017 Jun 23.
Diplostomid digeneans are important parasites whose larval stages infect freshwater snails and fish as first and second intermediate hosts respectively. Diplostomid digeneans as adults are parasitic in many fish-eating birds and mammals. Our understanding of the species diversity of diplostomid digeneans remains incomplete, especially in the Indian sub-continent. Here, we describe three Neascus-type metacercariae (N. hanumanthai, N. gussevi, and N. xenentodoni) from freshwater fish specimens of Channa punctata (Bloch 1793), Trichogaster fasciata (Bloch and Schneider 1801) and Xenentodon cancila (Hamilton, 1822) respectively, collected in India. Next, we characterised these metacecariae using nuclear (28S and ITS1) and mitochondrial DNA (cox1) to determine their systematic and phylogenetic position. Molecular identification using interspecific variation for all three molecular markers revealed a closer relationship between N. hanumanthai and N. gussevi (1.9%-2.4%) than either of N. hanumanthai and N. gussevi to N. xenentodoni (3.1%-3.7% and 4.4%-4.0% respectively). In phylogenetic analyses, estimated by neighbour-joining (NJ) and maximum likelihood (ML) methods, N. gussevi and N. hanumanthai nested as sister groups of Posthodiplostomum Dubois, 1936 for all three markers used; N. xenentodoni, however, nested as a sister taxa of all other diplostomes when using 28S and ITS1 and nested as a sister taxa of Bolbophorus, Alaria and Neodiplostomum using cox1. These findings suggest that N. hanumanthai and N. gussevi are members of Posthodiplostomum, but that N. xenentodoni belongs to a separate and unknown genus. Similarly, by proteomics, we found that the cox1 protein sequences and structures were similar between N. hanumanthai and N. gussevi but distinct for N. xenentodoni.
双穴吸虫是重要的寄生虫，其幼虫阶段分别感染淡水蜗牛和鱼类作为第一中间宿主和第二中间宿主。双穴吸虫成虫寄生于许多食鱼鸟类和哺乳动物体内。我们对双穴吸虫物种多样性的了解仍然不完整，尤其是在印度次大陆。在这里，我们分别描述了从印度采集的斑点鳢（Bloch，1793年）、条纹毛足鲈（Bloch和Schneider，1801年）和食蟹豆齿鳗（Hamilton，1822年）淡水鱼标本中发现的三种新穴属型囊蚴（哈努曼新穴吸虫、古氏新穴吸虫和食蟹豆齿鳗新穴吸虫）。接下来，我们使用核基因（28S和ITS1）和线粒体DNA（cox1）对这些囊蚴进行特征分析，以确定它们的系统发育位置。利用所有三种分子标记的种间变异进行分子鉴定发现，哈努曼新穴吸虫和古氏新穴吸虫之间的关系比哈努曼新穴吸虫和古氏新穴吸虫与食蟹豆齿鳗新穴吸虫之间的关系更密切（分别为1.9%-2.4%）（哈努曼新穴吸虫与食蟹豆齿鳗新穴吸虫之间为3.1%-3.7%，古氏新穴吸虫与食蟹豆齿鳗新穴吸虫之间为4.4%-4.0%）。在系统发育分析中，通过邻接法（NJ）和最大似然法（ML）估计，对于所有使用的三种标记，古氏新穴吸虫和哈努曼新穴吸虫嵌套为1936年杜氏后双穴吸虫的姐妹群；然而，当使用28S和ITS1时，食蟹豆齿鳗新穴吸虫嵌套为所有其他双穴吸虫的姐妹分类单元，而使用cox1时，食蟹豆齿鳗新穴吸虫嵌套为多盘属、艾氏属和新双穴属的姐妹分类单元。这些发现表明，哈努曼新穴吸虫和古氏新穴吸虫是后双穴吸虫属的成员，但食蟹豆齿鳗新穴吸虫属于一个单独的未知属。同样，通过蛋白质组学，我们发现哈努曼新穴吸虫和古氏新穴吸虫之间的cox1蛋白序列和结构相似，但食蟹豆齿鳗新穴吸虫不同。
