Figure 3.

Effect of atr1 and chk1 downregulation on synchronous mitosis in the dikaryon. (A) Examples of asynchronous mitosis. In A1 a hyphal tip cell is undergoing synchronous mitosis with one nucleus dividing at the clamp cell and the other one in the main hypha. In A2 and A3 nuclei are dividing at different times. Asterisks mark the dividing nuclei. Bar: 10 μm. (B) Quantification of the presence of asynchronous mitosis. The graph shows the result from two independent experiments, counting >50 mitotic cells each. Means and standard deviations are shown. Only apical cells that possessed two nuclei were analyzed. (C) Growing the cells in the presence of sublethal amounts of aphidicolin (AC), a replication inhibitor, increased the frequency of aberrant mitosis in chk1- and atr1-silenced strains. A total of 50 cells per experiment (two independent experiments) were counted per mutant. The lethal dose (i.e., absence of growth) of AC for wild-type cells in the experimental conditions was 100 μM. Means and standard deviations are shown.