重庆地区眉溪小车轮虫及其与近缘种的比较  

TRICHODINELLA MYAKKAE(MUELLER,1937)SRAMEK-HUSEK,1953 IN CHONGQING AREA AND COMPARAISON WITH ITS RELATED SPECIES

作　　者：夏萍 唐发辉[1] 赵元莙[1] XIA Ping;TANG Fa-Hui;ZHAO Yuan-Jun(Chongqing Key Laboratory of Animal Biology,College of Life Sciences,Chongqing Normal University,Chongqing 401331,China)

机构地区：[1]重庆师范大学生命科学学院,重庆市动物生物学重点实验室,重庆401331

出　　处：《水生生物学报》2021年第6期1371-1380,共10页Acta Hydrobiologica Sinica

基　　金：国家自然科学基金(31970409);重庆市自然科学基金(cstc2018jcyjAX0808);重庆市教委科学技术研究项目(KJQN201800508)资助。

摘　　要：通过活体显微观察和银染法,文章对采自重庆地区不同宿主的眉溪小车轮虫Trichodinella myakkae(Mueller,1937)Šrámek-HuŠek,1953的3个株系进行了详细的形态学描述,并与近缘种周丛小车轮虫Trichodinella epizootica(Raabe,1950)Šrámek-HuŠek,1953和纤细小车轮虫Trichodinella subtili(Lom,1959)Lom&Haldar,1977进行了比较。结果显示:眉溪小车轮虫各株系在形态上无明显差异,但与周丛小车轮虫及纤细小车轮虫有明显差异。基于所获眉溪小车轮虫的分子数据,详细分析了眉溪小车轮虫的分子特征,研究了眉溪小车轮虫种内分化,结果显示:眉溪小车轮虫各株系的18S rDNA序列相似度为99.2%—100%,遗传距离为0.000-0.003,T.myakkae(HM)与T.myakkae(AN)的18S rDNA几乎一致,但T.myakkae(PP)与T.myakkae(HM和AN)的18S rDNA存在7个变异位点,且在18S rRNA四个高变区(V3、V4、V5和V7)均具有一致的二级结构构型,表明三株系的18S rDNA相似度和遗传变异属于种内水平,但T.myakkae(PP)与T.myakkae(HM和AN)则显示出分子分化。系统发育分析显示:眉溪小车轮虫与周丛小车轮虫相互独立,眉溪小车轮虫各株系与其宿主鱼一致的系统发育关系显示出两者具有协同进化的趋势。Trichodinids are tiny parasitic ciliated protozoans with high diversity,and mainly parasitic in the fishes,shellfishes and rarely in coelenterates.The serious infections caused by trichodinids may induce damage to the hosts,or even death in severe cases.Many previous studies focused on morphology and taxonomy of trichodinids have been carried out worldwide.Because it is difficult to differentiate similar species based solely on morphological characters,molecular examination has been accepted for identification of species.In recent years,some studies have begun to apply molecular approaches to shed light on the past confusion of identification of taxa.It has been a long time since Trichodinella myakkae(Mueller,1937)Srámek-HuSek,1953 was confused with its relative species,Trichodinella epizootica(Raabe,1950)Srámek-HuSek,1953 and Trichodinella subtili(Lom,1959)Lom&Haldar,1977.It is also difficult to distinguish T.myakkae from other Trichodinella species by the only morphological characters,for T.myakkae shares similar shape and size to the related Trichodinella species and is often mixed infection with these trichodinids which are difficult to be isolated individually.Moreover,T.myakkae was reported from different regions around the world and mainly isolated from freshwater fish hosts,such as Ctenopharyngodon idellus,Aplites salmoides and other fishes.Therefore,it is of great significance to study phylogeny and the influencing factors of intra-species differentiation.This study collected three host fishes of Hypophthalmichthys molitrix,Aristichthys nobilis and Pseudorasbora parva for the examination of trichodinids.Under a binocular dissecting microscope,individual trichodinid was isolated from living host fishes by glass micropipettes.Three strains of T.myakkae were obtained,and their photomicrographs of silver impregnated specimen were provided.The PCA results showed that the morphological characteristics of the three strains were highly overlapping on the scatter plot.Besides,five 18S rDNA and ITS-5.8S rDNA seq

关 键 词：眉溪小车轮虫 种内分化 种类鉴定 协同进化 

分 类 号：Q959.116[生物学—动物学] S941.5[农业科学—水产养殖]