Incidence of petite colonies in Δduf1 and Δubp9 Δubp13 cells.

For each strain, one respiratory competent colony was streaked on glucose medium. After 3 days of incubation at 30°C, the resulting colonies, of both small and regular size, were individually checked for their respiratory competence. Most of the small colonies were not respiration-competent and were counted as petites colonies. These data were duplicated and similar results were obtained.