Molecular phylogeny of Yeasts and Yeast-like Fungi Based on Partial Sequences of 18S and 26S rRNAs

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During the last 3 years of the research period, we have published 14 original papers. 1) The genus Phaffia is characterized by the presence of xylose in the cells and the formation of starch-like compounds, and recognized as a synonym of the genus Cryptococcus. The determination of 18S and 26S rRNA partial sequences showed that the genus Phaffia exsist as a proper genus. 2) The anamorphic, ascomycetous yeast genus Aexula van der Walt, Smith et Yamada has the properties of the assimilation of purine bases as a sole source of carbon and of the antigens common to the ascomycetous, teleomorphic yeast genus Stephanoascus. The present experiment indicated that the above-mentioned two genera had partial base sequences in 18S and 26S rRNAs very close to each other. 3) The five Q10-equipped Rhodosporidium species were examined for partial sequences of 18S and 26S rRNA. Of the five species examined, the only species, R. dacryoidum had 11 base differences in the 18S rRNA partial sequence. The results obtained indicated that the species should be classified in its own separate genus. 4) The teleomorphic ascomycetous yeast. genus Holleya Yamada is characterized by the quinone system of Q-9 (Q-8). The sequence data obtained in 18S rRNA showed that the number of base differences was 7 between H. sinecauda and Nematospora coryli (Q-5 or Q-6), and indicated that the genus Holleya should be recognized as a genus separate from the genus Nematospora.