原生动物缘毛类纤毛虫的系统发育基因组学研究

Peritrichous ciliates have been known for more than 300 years as a distinct group, but there are a series of puzzling and unsolved phylogenetic problems of peritrichs. Selecting one representative species of mobline (a pathogens of fish disease, Trichodina nobilis) and five representative species of sessilines with the stalk ( Vorticella campanula, Carchesium polypinum, Zoothamnium arbuscula, Epistylis plicatilis and Campanella umbellaria) , we sequence their macronucleus genomes, and identify more orthologous genes (especially identify the genes encoding the components of adhesive disk, scopular, stalk and spasmoneme etc. combing the bioinformatic predictions and experimental data from transcriptome and proteome of adhesive disk and stalk), and construct the phylogentic trees using these gens, finally discuss the phylogenetic relationships among peritrichs and other subclasses of Class Oligohymenophorea, between moblines and sessilines, and among sessilines with stalk. The completion of this project will firstly gain the genomic data of peritrichs enriching the genomic resources of ciliates, and resolve the phylogenetic problems of peritrichs at the genome level; and open the door of phylogenomics of ciliates by setting up the strategy and technology for this field; also discuss the molecular mechanisms of Trichodina adapting to parasitic life and find some clues of drug targets for Trichodina disease.

缘毛类纤毛虫是最早被发现的原生动物类群，具有三百多年研究历史，但仍存在一系列系统发育学问题亟待解决。我们以游走目代表种、鱼病重要病原显著车轮虫，固着目代表种钟形钟虫、螅状独缩虫、树状聚缩虫、褶累枝虫和伞状聚钟虫为研究对象，在测定这六种缘毛类纤毛虫大核基因组的基础上，通过鉴定更多的直系同源基因（尤其是结合生物信息和转录组/蛋白组实验结果鉴定编码帚胚和附着盘等反口区结构的基因），进而基于这些基因重建系统发育树，利用系统发育基因组学研究方法探讨缘毛类与寡膜纲其它亚纲类群间、缘毛亚纲内游走目与固着目间、及各有柄固着类间的系统发育关系，不仅将首次获得缘毛类基因组数据、大大丰富纤毛虫基因组资源，在基因组水平解决缘毛类的系统发育学问题；而且将建立开展纤毛虫系统发育基因组学研究所需的策略和方法，开启该研究领域的大门；同时也将探讨游走缘毛类适应寄生生活的分子机制，为寻找防治车轮虫病的药物靶标提供重要线索。

缘毛类纤毛虫是最早被发现的原生动物类群，具有三百多年研究历史，但仍存在一系列系统发育学问题亟待解决。我们对14种代表性缘毛类纤毛虫进行基因组、转录组测序，开展系统发育基因组学研究表明：固着目与游走目聚为姐妹枝，支持缘毛亚纲单系；支持缘毛类与咽膜类亲缘关系更近。通过高分辨质谱分析，获得了螅状独缩虫（Carchesiumpolypinum）柄蛋白质组数据，并获得柄肌丝的关键基因--spasmin。对spasmin基因的分子进化分析说明柄肌丝的获得和丢失是固着缘毛类进化的关键性事件，而spasmin作为柄肌丝的关键组分是揭示固着缘毛类内部类群系统发育关系、该类群高度多样性和快速进化的分子基础。首次基于系统发育基因组学分析和化石记录，估测了纤毛虫、纤毛门各代表纲、缘毛类及内部类群的起源和分化时间。其中缘毛类纤毛虫起源于埃迪卡拉纪（617 mya），伴随着埃迪卡拉纪生物群的爆发产生；现存固着目和游走目（445 mya，469 mya）的分化发生在在寒武纪爆发之后的奥陶纪。