NUCLEAR BEHAVIOR OF RHODOSPORIDIUM TORULOIDES, A HETEROBASIDIOMYCETOUS YEAST

Nuclear behavior in the cells of Rhodosporidium toruloides, a heterobasidiomycetous yeast, was followed by microscopic observation. The behavior in the process of both asexual and sexual reproduction of the microorganism was found to agree, in principle, with the description on that of Leucosporidium sp., a heterobasidiomycetous yeast. In the artificially induced sexual differentiation in the cells of mating type a strain by A factor (a sex hormone secreted from the cells of mating type A strain), a complete repression of nuclear division occurs with the induction of mating tube formation. As elongation of the tube proceeds, a nucleus moves into the tube from the cell, followed by further migration to the apex of the tube. In the process of artificially induced dedifferentiation by removal of the factor from the incubation medium, the nucleus which was located in the mating tube by previous incubation with the factor recovers the ability to divide into two nuclei without formation of clamp connection. Then the septum formation occurs, followed by emergence of a bud. The bud grows and matures to a yeast cell.