Phylogeny and evolution of amitochondriate eukaryotes

为了阐明真核生物的早期进化，我们一直在利用多个分子序列数据研究原生动物包括海龙原生动物的系统发育关系。在这个项目中，我们建立了获得足够的DNA以进行原生生物基因分析的方法，这些原生生物包括蓝氏贾第鞭毛虫、阴道毛滴虫、柔嫩毛滴虫、溶组织内阿米巴、克氏锥虫、人双囊原虫、楔形脑孢子虫、海伦毛滴虫、小孢子虫和巴拉姆斯虫。根据这些原生质体的DNA，我们克隆并测定了编码异亮氨酰和valyl-tRNA合成酶、核糖体蛋白、7OkDa热休克蛋白和多肽延伸因子的基因，这些基因的序列尚未确定。包括这些原始数据在内的系统发育分析表明：1)所有来自非线粒体原生动物的序列都清楚地显示出典型的真核型的序列特征；2)所有4个非线粒体原生动物谱系--双单胞虫、旋毛虫科、双胞虫科和微孢子虫在进化过程中都继而失去了线粒体；

In order to elucidate early evolution of eukaryotes, we have been studying phylogenetic relationship aimng protists including arnitochondriate ones with the use of multiple molecular sequence data. In this project, we established the methods to get enough DNA needed for gene analyses of the protists, including Giardia lamblia (Diplomonads), Trichon2onas vaginalis, T. tenax (Trichomonads), Entamoeba histolytica (Entamoebidae), Trypanosoma cruzi (Euglenoids), Biastocystis hominis, Encephalitozoon cuniculi, E.heilein, Glugeaplecogiossi (Microsporidia), and Mastigarnoeba balamuthi. On the basis of the DNA of these protists, we cloned and sequenced the genes encoding isoleucyl- and valyl-tRNA synthetases, ribosomal proteins, 7OkDa heat shock proteins, and peptide elongation factors, the sequences of which had yet been detennined. Phylogenetic analyses including these original data suggested 1) that all the sequences from amitochondriate protists clearly show the sequence feature of typical eukaryotic type, 2) that all of the four amitochondriate protists lineages, Diplomonads, Tricbomonads, Entarnoebidae, and Microsporidia lost their mitochondria secondarily during their evolution, and 3) that B. hominis is involved in Stramenopiles and the closest relative of the Stramenopiles is shred by Alveolata.