犬弓首蛔虫线粒体cox1基因的克隆及序列分析

Analysis of Sequence Variation in Mitochondrial cox1 Gene of Toxocara canis Isolates in China

本研究旨在阐明我国犬弓首蛔虫（Toxocara canis）湖南分离株线粒体细胞色素c氧化酶第I亚基（cox1）基因部分序列（pcox1）的遗传变异情况,并用其与其它弓首蛔虫的pcox1序列构建进化关系。应用PCR扩增犬弓首蛔虫虫株的pcox1,将所获得的序列应用Mafft 7.122程序进行比对,然后用Phy ML 3.1程序ML法绘制种系发育树。本实验扩增所获得的pcox1序列长度一致,均为394 bp,种内变异在0~2.5%之间,种间差异为8.2%~11.6%。种系发育分析结果表明,12个犬弓首蛔虫分离株位于同一分支。由于犬弓首蛔虫pcox1序列种内相对保守,种间差异较大,故可作为种间鉴定检测研究的遗传标记,本研究结果为犬弓首蛔虫的分类、鉴定和群体遗传结构奠定了基础。

The objective of the study was to analyze sequence variation in the cytochrome c oxidase subunit 1（cox1）gene among Toxocara canis isolates from Hunan province and to study its phylogenetic relationship with other roundworms using the cox1 gene sequencing. The partial cox1（pcox1）were amplifi ed from individual T. canis samples,and pcox1 sequences were aligned using the Mafft 7.122. Maximum likelihood（ML）trees were constructed using the software Phy ML 3.1. The lengths of all pcox1 sequences were 394 bp. Sequence variations in pcox1 sequences within T. canis were 0~2.5% which was signifi cantly lower than inter-species differences（8.2%~11.6%）. Phylogenetic analyses showed that all T. canis isolates were clustered in the same clade. It was concluded that pcox1 sequence could be used as genetic marker for population genetic studies of T. canis,as well as genetic marker for the differentiation and identifi cation of different roundworms. The study provided foundation for further studies on molecular genetics and diagnosis of T. canis.