Interspecific and intraspecific mitochondria-induced cytoplasmic transformation in yeasts 1

Spheroplasts from respiratory-deficient (rho−) yeasts were transformed into rho+ cells by incubation with mitochondria prepared from respiratory-sufficient (rho+) yeasts in the presence of polyethylene glycol 4000 and CaCl2. Spheroplasts of budding yeast rho− strains were also transformed into rho+ cells by treatment with mitochondria prepared from heterospecific budding or fission yeast strains. All the transformed regeneratants yielded rho+ yeast colonies which bore chromosomal genetic characteristics of the spheroplasts used and cytoplasmic genetic characteristics of the mitochondria used. These indicate that mitochondrial genes or mitochondria themselves introduced by the incubation functioned normally in the rho− cells regardless of the species difference of the recipient spheroplasts.