1989 Volume 35 Issue 3 Pages 173-183
Ten strains of the Q8-equipped basidiomycetous yeasts classified in the genera Mrakia and Cystofilobasidium were examined for the partial sequence determinations of 18S rRNA and 26S rRNA. The positions determined (in S. cerevisiae) were through 1, 451 to 1, 618 of 18S rRNA and through 493 to 624 and through 1, 601 to 1, 832 of 26S rRNA. The three determinations of the partial sequences of 18S rRNA and 26S rRNA divided the strains examined into two separate groups corresponding to the genera Mrakia and Cystoftlobasidium. Group I contained the strains of M. frigida, M. gelida, M. nivalis, and M. stokesii, and group II contained the strains of C. bisporidii, C. capitatum, and C. infirmominiatum. The inclusion of R. infirmominiatum in the genus Cystofilobasidium as C. infirmominiatum was proved to be phylogenetically reasonable. The data obtained indicate that the division of the Q8-equipped basidiomycetous yeasts into the two genera mentioned above is more natural from the phylogenetic point of view. The utilization of the partial sequences of 18S rRNA and 26S rRNA is discussed, especially in the positions through 1, 451 to 1, 618 of 18S rRNA, for the classification of yeasts (and yeast-like fungi).