Pattern of somatic segregation of the cytoplasmic drug-resistance factors in yeast.

The pattern of somatic segregation of the cytoplasmic factors confering resistances to chloramphenicol, erythromycin and oligomyin in S. cerevisiae was studied. The fractions of the zygotes heterozygous for the chloramphenicol-resistance factor and for the erythromycin-resistance factor decreased exponentially with generation number of zygotes. The rate of the segregation was highest for the chloramphenicol-resistance factor and lowest for the oligomycin-resistance factor. The segregation rate as well as the transmission polarity of the chloramphenicol-resistance factor varied with different carbon sources with which the parental haploids were grown prior to mating.