Janus green resistance in Saccharomyces cerevisiae: interaction of nuclear and cytoplasmic factors.

Janus green B was found to be a specific inhibitor of mitochondrial function in yeast. This is consistent with the Janus green specificity in supravital staining of mitochondria. A mutant of S. Cerevisiae resistant to Janus green B was isolated. It shows cross resistance to oligomycin, ethidium bromide and a weak resistance to chlormaphenicol. The mutant was found to be sensitive to cycloheximide and erythromycin. Genetic analysis of this mutant showed that mitochondrial genes are not involved in the determination of Janus Green resistance. Tetrad analysis suggested that two more more nuclear genes are concerned, but many unusal genetic features suggestive of the involvement of a cytoplasmic element remain to be explained.