Figure 1.

(A) Hypertonic stress results in a depletion of S phase cells from an asynchronous culture. Log phase cultures of wild-type MT588 were stressed by the addition of NaCl to a final concentration of 0.4 M. Samples were taken at the indicated times, and processed as described (see MATERIALS AND METHODS). The cellular DNA was stained with propidium iodide and analyzed by flow cytometry. Histograms were generated by using WinMDI software for the PC. Similar results were obtained in three separate experiments. (B) Hypertonic stress delays exit from G1. Wild-type MT588 were arrested in alpha factor, released, and stressed at time zero by the addition of 0.4 M NaCl. Budding index and ratio of 1N to 2N cells was determined for no salt control (solid line) and 0.4 M NaCl treated (dashed line) and plotted versus time in minutes after addition of NaCl.