Evidence for an extrakaryotic mutation affecting the maintenance of the rho factor in yeast

A newly isolated, temperature-sensitive mutant of a haploid strain of Saccharomyces cerevisiae is described. Its shift to nonpermissive temperature (35 C) resulted in an irreversible change to rho(-), causing, within four to six generations, more than 90% of the cells to form petite colonies. Genetic analysis revealed extrakaryotic inheritance of this temperature-sensitive mutation. Data presented indicate mutation of a gene in the mitochondrial deoxyribonucleic acid affecting the maintenance of the rho factor.