Effect of DNA damaging agents and hydroxy urea on
(A) 102 cells of csn mutant strains were spotted onto YPD plates followed by irradiation with the indicated doses of UV light (0 – 120 J/m2). The UV-sensitive Δrad14 strain was used as a positive control for the effect of UV. (B) 102 cells of csn deletion strains were spotted onto a YPD gradient plate containing 0% to 0.03% methyl-methane sulfonate (MMS) as indicated. Plates were incubated for 3 days at 30°C. The MMS-sensitive strain Δrad14 is shown as a positive control for the effect of MMS. (C) 102 cells of csn deletion strains were spotted onto a YPD gradient plate containing 0 to 200 mM hydroxyurea (HU) as indicated and cell growth was determined after incubation for 3 days at 30°C. The HU-sensitive strain Δpol32 is shown as a positive control for the effect of HU. (D) The indicated wild-type and csn deletion strains were grown in YPD to an optical density of ~1, followed by fixation in 70% ethanol. Cells fixed for 24 h at -20°C were washed once in 50 mM sodium citrate and resuspended in the same buffer containing 100 ug/ml preboiled RNAse A, followed by incubation at 37°C for 2 h. Propidium iodide was added to a final concentration of 4 ug/ml, and the cellular DNA content was determined by flow cytometry.