Figure 4

Low-level expression of the PA incompatibility domain results in fewer and larger cells. A) The number of cells in a 1 mm diameter colony was determined by cell counts with a haemocytometer. Significantly fewer cells were present in colonies of PA-expressing strain than the control strain (P = 0.003). Error bars represent standard deviation from 5 biological replicates. B) Volume measurements of cells grown on YPD show that PA-expressing cells were on average significantly larger than those of the control strain and the vacuolar ATPase mutant, YPL234C (P < 0.001, Wilcoxon/Kruskal Wallis test). Volumes were grouped into 50 μm³ bins and plotted. Inset: The average cell volume (±SD) of the three strains with shading as in main figure. C) PA-expressing yeast had increased sensitivity to hydroxyrurea, a potent inhibitor of RNR activity, when compared to the control strain and the vATPase-defective strain YPL234C, as determined through MIC measurements. Error bars represent standard deviation of 5 biological replicates.