几种常见吸虫的分子系统发生学研究

STUDIES ON MOLECULAR PHYLOGENY OF SEVERAL TREMATODES

目的 研究日本血吸虫、卫氏并殖吸虫、华支睾吸虫、布氏姜片吸虫和肝片形吸虫分子系统发生学的关系。方法 利用PCR技术特异性扩增日本血吸虫、卫氏并殖吸虫和华支睾吸虫核糖体小亚基(18SrDNA)的V4区基因并测序。根据Genebank,检索布氏姜片吸虫和肝片形吸虫的相关序列,并与上述3种吸虫的V4区基因序列进行排列比较,计算它们的遗传距离并构建系统发生树。 结果 日本血吸虫与其他吸虫的遗传距离远>其他吸虫之间的遗传距离,在分子系统发生树中,日本血吸虫单独形成一个支系,其他吸虫形成另外一个支系。 结论 日本血吸虫与其他吸虫的亲缘关系较远,它们可能来自不同的祖先。

Objective To study the molecular phylogeny of Schistosoma japonicum , Clonorchis sinensis, Paragonimuswestermani, Fasciolahepal-ica and Fasciolopsisbuski. Methods The 18S rDNA V4 regions of S. japonicum, C. sinensis and P. westermani were specifically amplified by PCR. The PCR products were purified and sequenced. The correspondent sequences of F. hepatica and F. buski were searched from Genbank. All these sequences were aligned and compared using Clustal W program. The genetic distances among the trematodes were calculated using Kimura 2-pa-rameter. The phylogenetic tree was constructed using neighbor-joining method and the statistical confidence of a particular cluster sequences was tested by the bootstrap procedure (1 000 replicates). Results The genetic distances among S. japonicum and the other four trematodes were much further than those among the other four trematodes. The phylogenetic tree obtained by neighbor-joining method showed S. japonicum as a sister taxon to the other trematodes. Conclusion The kinship between S. japonicum and other trematodes is not so close, it indicated that they may originate from different ancestors.