鲫寄生7种指环虫的形态学和分子鉴定

MORPHOLOGICAL AND MOLECULAR IDENTIFICATION OF 7 SPECIES OF DACTYLOGYRUS ON GILLS OF THE GOLDFISH(CARASSIUS AURATUS)

指环虫(Dactylogyrus sp.)是鲫(Carassius auratus)鳃部重要的致病寄生虫,为调查鲫的指环虫种类,采用形态学与分子生物学相结合的方法,对梁子湖鲫的单殖吸虫进行了种类鉴定。通过对指环虫后吸器几丁质结构的形态特征描述和测量,发现鳃部共有7种指环虫,分别鉴定为坏鳃指环虫(D. vastator)、中型指环虫(D.intermedius)、弧形指环虫(D. arcuatus)、弓茎指环虫(D. baueri)、美丽指环虫(D. formosus)、望外指环虫(D.inexpeatatus)及叉茎指环虫(D. dulkeiti)。中型指环虫、美丽指环虫和叉茎指环虫与GenBank中相应指环虫的18S+ITS1+5.8S rDNA序列的相似性均高于99.0%,弧形指环虫的基因序列为首次提交。而坏鳃指环虫与GenBank中相应的指环虫序列相似度仅有96.37%,遗传距离分析显示,坏鳃指环虫的种内遗传距离较大(0.004—0.058),但小于坏鳃指环虫与中型指环虫的种间遗传距离(0.046—0.064)。研究重新描述我国鲫7种指环虫主要形态学分类特征,并提供分子分类数据,为鲫寄生指环虫的种类鉴定提供参考依据。

Dactylogyrus species has high pathogenicity to the goldfish(Carassius auratus). In order to investigate the species of Dactylogyrus, we identified specimens of dactylogyrids collected from gills of the goldfish in Liangzi Lake,Hubei Province, based on morphological and molecular data in the present study. There were seven Dactylogyrus species, including D. vastator, D. intermedius, D. arcuatus, D. baueri, D. formosus, D. inexpeatatus and D. dulkeiti. The morphometric characteristics of sclerotized parts of the opisthaptor in these dactylogyrids were measured and redescribed. D. intermedius, D. formosus and D. dulkeiti were identified by the higher than 99.0% similarities of 18S+ITS1+5.8S partial sequences to the related Dactylogyrus species from the GenBank. The sequence of D. arcuatus was obtained for the first time. However, the sequence similarity between D. vastator and the related Dactylogyrus species from the GenBank was only 96.37%. In addition, high Kimura-two-parameter genetic distances(0.004—0.058)were detected among D. vastator using partial 18S rDNA and ITS1 sequences, but lower than the interspecific variability(0.046—0.064) between D. vastator and D. intermedius. In the present study, the morphological characteristics of Dactylogyrus were redescribed comprehensively and molecular classification markers were sequenced, which provided the basic data and a reference for the identification of Dactylogyrus species on the gills of the goldfish.