Figure 2.

The rpo41Δ3 mutation results in mtDNA instability. (a) GS125 rho^o was used as a control for cells completely lacking mtDNA. (b) GS125 was grown at 30°C in YPG medium and used as a positive control for mtDNA staining. Punctate cytoplasmic mtDNA staining was observed in these cells in addition to nuclear DNA staining. Representative petite colonies generated by growth of GS125 for 12 generations at 37°C are shown in c and d. In ≈50% of the colonies tested, none of the cells exhibited an mtDNA signal, [rho^o] (c), while the remainder consisted of a mixture of [rho^o] cells and cells that exhibited some mtDNA signal (d).