基于线粒体细胞色素b基因的细颈囊尾蚴种群遗传多样性研究

为探讨我国细颈囊尾蚴种群之间的遗传相似性及与其他带科带属绦虫的亲缘关系,用线粒体细胞色素b(Cyt b)基因全序列研究了分离自我国四川和云南2省7地区猪、山羊和绵羊共33个细颈囊尾蚴的遗传变异,并用MEGA 4.0程序NJ法和PAUP 4.0程序MP法绘制种系发育树.本研究结果显示:细颈囊尾蚴分离株的Cyt b基因全长为1 068 bp,共检测到22个单倍型,单倍型间核苷酸相似性较高(97.3％～99.9％),其与带科带属其他5种绦虫的相似性均在82％以下.系统发育树显示,7个不同地域的细颈囊尾蚴聚为一支,分为3个亚群,且与地理区域、宿主没有直接的相关性,呈现混杂的分布格局,未形成明显的地理分支或宿主分支.研究结果表明:细颈囊尾蚴Cytb基因存在一定的遗传差异,但种内相对保守,与其他带科绦虫种间差异较大,故可作为种间遗传变异研究的标记,并为细颈囊尾蚴的种群遗传学研究及其与其他带科绦虫病的鉴别诊断的建立奠定基础.

Analysis of Genetic Variation in Different Populations of Cysticercus tenuicollis Based on the Mitochondrial Cytochrome b Gene

The objective of this study was to examine genetic similarity of C.tenuicollis among populations from different regions,and the phylogenetic relationships with other taenia species.The complete sequences of mitochondrial Cytochrome b(Cyt b) gene were used to investigate the intraspecific genetic subdivision of 33 C.tenuicollis isolated from seven different cities in Sichuan and Yunnan Province,NJ tree and MP tree were constructed using the MEGA version 4.0 software and PAUP version 4.0,respectively.The results showed that the complete sequence of Cyt b gene of C.tenuicollis was 1 068 bp,and 22 haplotypes were detected,homology analysis indicated that the homology identity levels of nucleotides of Cyt b gene among haplotypes were high,ranged from 97.3% to 99.9%,but the homology identity levels of nucleotides of isolates in this study and other 5 kinds of taenia spp.cestodes in taeniidae were below 82%.The phylogenetic trees based on Cyt b gene showed that all the haplotypes of seven populations were formed a single cluster that could be divided into three subgroups.There was no direct relationship to geography or host,appeared disordered distribution pattern which there was not obvious geography cluster or host cluster.There were some genetic differences in Cyt b gene within C.tenuicollis,but no significant variation,while interspecies difference was obvious.It was concluded that Cyt b gene can be used as genetic marker for population genetic studies of cestodes.The results of the present study provided foundation for further studies of population genetics of C.tenuicollis,and for the differential diagnosis of taeniid tapeworm infections.