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目的卡氏肺孢子虫作为肺炎的病原物,其分类地位一直存在争议.近二十年来,关于卡氏肺孢子虫的分子生物学证据多支持其为真菌的观点,但卡氏肺孢子虫在真菌内部的分类地位需要确定.方法本研究在swissprot数据库中搜集真菌和卡氏肺孢子虫中的肌动蛋白、α微管蛋白和钙调素这三种保守蛋白的氨基酸序列,使用phylip3.6a软件中的邻接法构建三种保守蛋白的系统树,从而探讨卡氏肺孢子虫的分类地位.结果三种蛋白的分子系统树都支持了将卡氏肺孢子虫作为子囊菌的早期分支古子囊菌的分类观点.结论古子囊菌可能并不是一个单起源群.“,”[Objective] Pneumocystis carinii has been the most frequent cause of morbidity and mortality in patients with AIDS. As a eukaryotic pathogen, its phylogeny has been controversial for many years. Molecular evidence accumulated in recent 20 years supported the placement of Pneumocystis carinii as a fungus, however, its phylogenic place within fungi is still unclear. [Methods] Molecular phylogeny of three conservative proteins is constructed to elucidate the phylogeny of Pneumocystis carinii in fungi. Amino acid sequences of actin, αtubulin and calmodulin in fungi are collected from the swissprot database and phylogenic trees are constructed using neighbor-jioning method in phylip3.6a software. [Results] From the phylogenetic tree of acitns in fungi Pneumocystis carinii and Schizosaccharomyces pombe are in an early branch of Ascomycota. In the phylogenetic tree of calmoduins in fungi, Pneumocystis carinii and Schizosaccharomyces pombe are early branches of Ascomycota called Archiascomycetes. Theαtubulin tree also supports the placement of Pneumocystis carinii and Schizosaccharomyces pombe in Archiascomycetes and the polyphyletic origin of this lineage. [Conclusion] The phylogenic trees of the three proteins support the placement of Pneumoeystis carinii in Archiascomycetes and the polyphyletic origin of Archiaseomycetes.