Cytoduction as a new tool in studying the cytoplasmic heredity in yeast

When crossing the haploid cells of genetically marked yeast strains we observed the appearance of both normal diploid zygotes and haploid nuclear cytoplasmic hybrids. The latter had the nuclear markers of one and the cytoplasmic marker (rho+) of the other parent. The autonomous cytoplasmic factor transfer was termed as cytoduction. Cytoduction is supposed to be the abortive form of yeast cell mating. Only about 1% of cytoductants in usually observed. Cytoduction can be used as a simple test on cytoplasmic determination of some characters. We observed the transfer into cytoductant cells of not only rho+ marker but of resistance factors to antibiotics (erythromycin, neomycin) and killer factor as well. Cytoduction can be applied towards constructing strains having the identical nucleus genotype with mitochondria and other cytoplasmic factors of different origin. In crossing strains with doubly marked mitochondria recombination of mitochondrial markers in cytoductant haploid cells was observed, the pattern of which was similar to that of mitochondrial recombination in normal zygotes.