Xiong Fan, Li Wen X, Wu Shan G, Zou Hong, Wang Gui T
The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, and Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
J Parasitol. 2013 Feb;99(1):137-44. doi: 10.1645/GE-3163.1. Epub 2012 Aug 27.
The nematodes Eustrongylides spp. collected from different fish species in China were examined for their intra- and interspecific evolutionary variations using the molecular markers mitochondrial cytochrome oxidase c subunit 1 (COI) gene and internal transcribed spacer (ITS) rDNA regions. The phylogenetic analysis indicated that Eustrongylides species are divided into 3 well-supported clades. The ITS divergence between the clades suggested that clades 2 and 3 might represent the same species, whereas clade 1 represent another cryptic species. The host specificity of these nematodes was analyzed according to prevalence data, host range, and phylogenetic information. Clade 1 was found in 4 fish species, i.e., Odontobutis obscurus, Silurus asotus, Culter mongolicus, and Acanthogobius flavimanus, but was predominant in the 2 perciform species, O. obscurus and A. flavimanus. Clade 2 was found in 3 fish species, Monopterus albus, Channa argus, and Channa asiatica, but was predominant in M. albus, reported to feed primarily on oligochaetes, the first intermediate host of Eustrongylides sp. Clade 3 was found in 9 species, but its low prevalence suggests accidental infection in all species. Although the larval nematode presented low host specificity, it exhibited some host preference.
利用线粒体细胞色素氧化酶c亚基1（COI）基因和内转录间隔区（ITS）rDNA区域等分子标记，对在中国不同鱼类中采集到的真圆线虫属线虫进行种内和种间进化变异研究。系统发育分析表明，真圆线虫物种分为3个得到有力支持的进化枝。进化枝之间的ITS差异表明，进化枝2和3可能代表同一物种，而进化枝1代表另一个隐存种。根据感染率数据、宿主范围和系统发育信息分析了这些线虫的宿主特异性。在4种鱼类中发现了进化枝1，即暗纹东方鲀、鲶鱼、蒙古红鲌和黄鳍刺虾虎鱼，但在2种鲈形目鱼类暗纹东方鲀和黄鳍刺虾虎鱼中占主导地位。在3种鱼类中发现了进化枝2，即黄鳝、乌鳢和月鳢，但在黄鳝中占主导地位，据报道黄鳝主要以寡毛纲动物为食，寡毛纲动物是真圆线虫属的第一中间宿主。在9种鱼类中发现了进化枝3，但其低感染率表明所有物种均为偶然感染。虽然幼虫线虫表现出较低的宿主特异性，但仍表现出一定的宿主偏好。
