| Research Abstract |
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.
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