Differential effect of the alkaloid lycorine on rho (+), mit (-), rho (-), and rho (o) strains of Saccharomyces cerevisiae.

The alkaloid lycorine inhibits growth of rho (+), mit (-), and rho (-) strains, whereas rho (0) strains (devoid of mitochondrial DNA) of Saccharomyces cerevisiae are resistant to high concentrations of the drug. The inhibitory effect of lycorine on the growth of rho (+) strains can be counteracted by the addition of ascorbic acid to the plating medium. Lycorine induces cytoplasmic respiratory deficient mutants upon growth in glucose complete medium containing the alkaloid. The minimal inhibitory concentration of lycorine in glucose complete medium is ten times higher than in glycerol complete medium, thus demonstrating its preferential action on mitochondrial functions. Total protein synthesis and mitochondrial protein synthesis are only slightly inhibited by lycorine. It has, however, an inhibitory effect on DNA and RNA synthesis.