Complete absence of mitochondrial DNA in the petite-negative yeastSchizosaccharomyces pombe leads to resistance towards the alkaloid lycorine

The petite-positive yeastSaccharomyces cerevisiae can be efficiently and completely converted to respiratory-deficient cytoplasmic petite mutants by intercalating drugs.Rho^o petites fromSchizosaccharomyces pombe could only be obtained in strains carrying a nuclear mutation. In this paper we report the efficient isolation ofrho^o mutants in aSch. pombe strain containing a mitochondrial mutator mutation. We also show that the alkaloid lycorine is able to differentiate between cells containing defective mitochondrial DNA (mit^–) and those lacking mitochondrial DNA completely (rho^o).Rho^o cells are resistant to the alkaloid whereasmit^– and wild-type cells show the same sensitivity.