罗非鱼寄生嗜丽鱼虫的形态描述及系统发育研究

Morphological Description and Phylogeny of Tilapia Parasitic Cichlidogyrus

2018年11月至2019年5月,在乌鲁木齐市周边市场及养殖场进行鱼类寄生虫调查过程中发现,不同地域的罗非鱼鳃部有大量锚首虫寄生,经染色观察,对后吸器及交接器等结构进行绘图、测量,同时选用28S、18S-ITS1-5.8S和COⅠ3个分子标记进行扩增、克隆和序列测定,利用核糖体RNA与相关物种进行系统发育分析。研究结果显示,形态学结果可初步鉴定,该虫体为锚首虫亚科嗜丽鱼虫属的几丁嗜丽鱼虫和彼丽嗜丽鱼虫。扩增得到几丁嗜丽鱼虫的28S、18S-ITS1-5.8S及COⅠ序列长度分别为863、1019 bp和592 bp,与GenBank中已发表的几丁嗜丽鱼虫的相似性均超99.5%;扩增得到彼丽嗜丽鱼虫的28S、18S-ITS1-5.8S及COⅠ序列长度分别为863、1005 bp和572 bp,与GenBank中的彼丽嗜丽鱼虫的相似性均超94%,且与刀茎嗜丽鱼虫的相似性均达99.3%以上。从基于核糖体RNA所构建的最大似然树和遗传矩阵来看,本试验中几丁嗜丽鱼虫与不同地区的几丁嗜丽鱼虫聚为一支,且遗传距离均为0;彼丽嗜丽鱼虫与巴西的彼丽嗜丽鱼虫、捷克的刀茎嗜丽鱼虫聚成的拓扑结构自展值为99%和100%,且遗传距离为0.000~0.003,其结果与形态学结果相一致。试验结果补充了该虫在国内分子方面的资料,同时从分子生物学角度彼丽嗜丽鱼虫与刀茎嗜丽鱼虫为同物异名的分类观点提供支撑。

From November 2018 to May 2019,during the investigation of fish parasites in the markets and farms aroundürümqi City,it was found that there were a large number of Ancyrocephalidae in the gills of tilapia in different regions.After dye observation,the structure of the copulatory organs and haptors were mapped,measured and compared.At the same time,three molecular markers(28 S,18 S-ITS1-5.8 S and COⅠ)were selected for amplification,cloning and sequencing and phylogenetic analysis was carried out with ribosomal RNA and related species.The results showed that the morphological characteristics preliminarily identified the anchored worm as Ancyrocephalidae,Cichlidogyrus sclerosus(MJ 12)and C.mbirizei(MJ 23 or MJ 33)in Cichlidogyrus.The 28 S,18 S-ITS1-5.8 S and COⅠsequence fragment size of MJ12 were 863 bp,1019 bp and 592 bp,respectively,the similarities with C.sclerosus published in Genbank were above 99.5%;the 28 S,18 S-ITS1-5.8 S and COⅠsequences of MJ23 were 863 bp,1005 bp and 572 bp,respectively,the similarity between MJ23 and C.mbirizei in GenBank was over 94%,and the similarity between MJ23 and C.cirratus was over 99.3%.According to the ML tree and genetic matrix constructed based on ribosomal RNA,MJ12 and Chitin cichlids from different regions are clustered together,and the genetic distance was 0;the topological structure formed by MJ 23 or MJ 33 and the C.mbirizei in Brazil and the C.cirratus had a self-expanding value of 99%and 100%,with genetic distance of 0.000—0.003,consistent with the morphological result.The findings supplemented the domestic molecular data of the worm,and also supported the viewpoint of the classification of synonymy species of C.mbirizei and C.cirratus.