线粒体cox1序列分析支持北半球欧氏对盲囊线虫是一个新种

Sequence analysis of mtDNA cox1 gene indicates that contracaecum ogmorhini from the northern hemisphere represents a new species

欧氏对盲囊线虫 (Contracaecumogmorhini )是一种重要的人畜共患寄生虫病—异尖线虫病的病原之一。来自南北半球三个不同种群的C ogmorhini有着明显的地理分布差异和宿主特异性。应用PCR_SSCP技术分析了三个不同地理株的C ogmorhini在线粒体DNA(mtDNA)细胞色素c氧化酶第I亚基 (cox1)部分序列的差异及种群遗传关系。用同位素 (γ3 3 P)对保守引物进行标记 ,通过PCR从单个欧氏对盲囊线虫DNA中扩增出一条长为 4 4 1bp的cox1基因片段 ,取阳性PCR扩增产物 ,对三个不同地理株的C ogmorhini进行SSCP分析 ,结果显示 :三个不同地理株的C ogmorhini4 4 1bp的cox1基因片段存在着一定的多态性 ,其中南半球的不同地理株其SSCP带型差异很小 ,而北半球和南半球的带型差异则略微明显。将SSCP分析筛选出的代表性样品进行克隆、测序 ,序列分析表明 :南半球的样品序列同源性很高 ,而北半球种群与南半球种群的序列同源性则相对较低 ,它们之间存在着 3个可作为其遗传标记的基因位点 ,从而说明北半球的C ogmorhini相对于南半球的C ogmorhini来说确实存在着遗传差异 ,很可能代表着一个新种。

Contracaecum ogmorhini is one of the causative agents for anisakiasis,which is an important parasitic zoonosis.The present study examined the nucleotide difference in a portion of the mitochondrial cytochrome coxidase subunit 1?gene (pcox1)among three populations of C.ogmorhinifrom different otariid hosts and geographical origins.pcox1 of approximately 450 ?bp in length was amplified by PCR using^(33) P-endlabelled primers and the amplifications were analysed by single-strand conformation polymorphism (SSCP).The results showed that polymorphism existed in SSCP profiles of pcox1 among different samples from different geographical origins or the same origins.The difference in the SSCP profiles between CoAPP and CoAPD was not significant,however the difference between CoZC and CoAPP/CoAPD was relatively distinct.Sequence analysis revealed that the nucleotide similarity between CoZC and CoAPP/CoAPD was obviously lower than that between CoAPP and CoAPD.Three genetic markers were defined for the differentiation between CoZC and CoAPP/CoAPD.These findings suggested that C.ogmorhini represents a complex of at least two species,in other words,C.ogmorhini from the northern hemisphere may represent a new species.