基于线粒体基因组序列的同盘吸虫系统发育研究

Paramphistomidae spp. are neglected but important trematodes that endanger livestock industry and human health. Accurate identification and differentiation of paramphistomid species is essential for diagnosis, treatment, prevention and control of paramphistomiasis. Due to the lack of the generally accepted morphological criteria for the classification at family, subfamily or generic levels, it is difficult to accurately identifiy paramphistomid flukes through traditional morphologic approach. Moreover, lacking efficient genetic markers in the available gene sequences makes it hard to conduct the molecular identification of paramphistomid species accurately. Thus, there has been considerable debate over the nomenclature and systematics in Paramphistomidae. Mitochondrial (mt) genome sequences have been proven to be useful genetic markers for studying the taxonomy, population genetics, evolution and phylogenetics of parasites. However, the research on decoding the complete mt genomic datas of paramphistomid flukes is limited, and only three complete mt genome sequences have been decoded in the Paramphistomidae. The objective of the present project is to determine and compare the mt genomes of several important paramphistomid species, analyze the structural features, and construct the phylogenetic relationships with other digenea species. Using mt genome sequence will examine and clarify the controversies of classification, and illuminate the higher-level systematics and phylogenetics of Paramphistomidae.

同盘吸虫是一类危害严重但被忽略的人畜共患吸虫。对同盘吸虫进行准确的鉴定分类是正确诊治和防控同盘吸虫病的基础和前提。由于缺乏被普遍认可的同盘科、各亚科及各属的形态学鉴定标准，很难做出准确的形态鉴定；现公布的同盘科少数吸虫种属的少量基因片段，也因缺乏有效的遗传信息而难以依此做出准确的分子分类及鉴定，因而同盘吸虫的分类及系统发育存在很多争议。线粒体基因组序列是研究寄生虫的分类鉴定、种群遗传、进化状况以及系统发育关系的可靠分子标记，但对同盘吸虫这一重要类群线粒体基因组的研究较少，目前仅3种同盘吸虫的线粒体基因组全序列被解析。本研究拟解码该科几种重要同盘吸虫的线粒体基因组全序列，分析同盘科吸虫线粒体基因组结构特征并构建与其它复殖亚目吸虫的系统发育关系；通过比较吸虫线粒体全基因组数据，重新检视同盘科内争议不断的种属分类现状，厘清几种同盘吸虫的分类混乱问题，阐明同盘吸虫高级阶元分类地位及系统发育关系。

对吸虫进行准确的鉴定和分类是诊断、防治和控制吸虫病的前提和基础。由于形态学（易受环境影响）和少量基因片段序列（缺乏有效的遗传信息位点）在分类上的局限性，吸虫分类和其高级阶元的系统发育仍颇具争议。线粒体基因组序列是研究寄生虫分子分类、群体遗传、系统进化的一种很好的分子标记。申请者解码了8种吸虫的线粒体基因组，分析其线粒体基因组结构特征并构建其与其他吸虫的系统发育关系。基于12个PCGs的连续的氨基酸（或核苷酸）序列，本项目研究了7种吸虫（源于三个亚目的四个科）与相关吸虫的系统发育关系，并首次提出，相对于双腔科，并殖科更接近斜睾科和Brachycladiidae科；本实验认可环肠科位于棘口目；通过分析Hepatiarius sudarikovi和Opisthorchis felineus的ITS rDNA及mt基因组序列的高度相似性并结合系统发育分析，建议将H. sudarikovi归入Opisthorchis后睾属；证实来自厄瓜多尔的对体吸虫不归属于后睾属；首次解码了斜睾科Plagiorchis maculosus、环肠科Uvitellina sp. 双腔科短腺属，短盘属，窄体属的代表性物种。本研究首次提供了来自这些吸虫的rDNA和mt基因组序列，不仅为研究这些吸虫的分类、鉴定、诊断检测提供了新的分子标记，也为进一步研究复殖吸虫的系统发育提供了新的数据。.在完成上述研究的基础上，也完成了5种棘头虫的线粒体基因组的解析。