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目的研究三峡库区上、下游血吸虫病流行区钉螺线粒体DNA细胞色素C氧化酶亚单位1(cox1)基因的遗传变异。方法采集三峡库区上游四川、云南及下游安徽、湖北4省共7个地、市的钉螺样本,提取基因组DNA,PCR特异性扩增线粒体cox1基因并测序,用ClustalX(1.81)软件进行多序列比对,MEGA(4.0)软件Kimura2-parameter法计算遗传距离,邻接法(NJ)和最大简约法(MP)构建系统发生树。结果上游与下游不同地域株钉螺间cox1基因差异约为16%,下游地区的肋壳与光壳钉螺cox1基因差异约为3.7%,上游不同地域株钉螺碱基差异约为5.4%。遗传距离显示,上游四川与云南地域株的遗传距离为0.022～0.050,下游安徽与湖北地域株的遗传距离为0.014～0.027,而上游与下游各地区螺群间的遗传距离在0.127～0.138之间,明显大于上游或下游各地区螺群内的遗传距离。进化树结果表明,下游湖北的荆州、石首和安徽的芜湖、宁国钉螺形成一支系,上游四川的绵竹、新都钉螺同属一支系,但两种方法构建的进化树在云南大理钉螺的归属上存在差异,MP法提示大理钉螺从上游的分支中独立出来,单独形成一类。结论上游与下游不同地域株钉螺cox1基因遗传差异较显著,下游肋壳和光壳钉螺种群内遗传变异较小,而上游光壳钉螺种群内遗传变异较大。
Objective To study the genetic variation of mitochondrial DNA cytochrome C oxidase subunit 1 (cox1) gene in snails in the upper and lower reaches of the Three Gorges Reservoir area. Methods Genomic DNA was extracted from 7 snakehead specimens in Sichuan, Yunnan, the lower reaches of the Three Gorges Reservoir area, and 4 in the lower reaches of Hubei and Hubei Provinces. The mitochondrial COX1 gene was amplified by PCR and sequenced. The ClustalX (1.81) By using the Kimura2-parameter method of MEGA (4.0) software, the phylogenetic trees were constructed by using genetic distance, neighbor method (NJ) and maximum parsimony (MP). Results The cox1 gene difference was about 16% between the upstream and downstream strains. The cox1 gene difference between the rib shell and the light shell snail in the downstream region was about 3.7%, and the snail base difference in the upstream region was about 5.4%. The genetic distance showed that the genetic distance between upstream Sichuan and Yunnan was 0.022-0.050, the genetic distance between Anhui and Hubei was 0.014-0.027, while the genetic distance between the upper and lower reaches was between 0.127 and 0.138 , Which was significantly greater than the genetic distance within the spiral group in the upstream or downstream regions. The results of the phylogenetic tree showed that the southern snails of Jingzhou and Shishou in Hubei Province and Wuhu and Ningguo of Anhui Province formed a lineage. The Mianzhu and Xinduansha of the upper reaches of Sichuan Province belonged to the same family. However, There are differences in the ownership, MP method to remind Dali snail independent from the upstream branch, forming a separate category. Conclusion The cox1 gene of Oncomelania snail in the upstream and downstream regions has significant genetic differences. The genetic variation in the lower rib shell and the light snail population is small, while the genetic variation in the snail population is relatively high.