FIG. 3.

Chromatin fragmentation and apoptosis factors are not involved in tunicamycin-induced cell death. Wild-type yeast strains were grown in YPD medium (A, B) or SC medium (C), supplemented with nothing (black lines), 4 mM hydrogen peroxide (red lines), 2.5 μg/ml tunicamycin (blue lines), or 2.5 μg/ml tunicamycin plus 1 μg/ml FK506 (green lines) for the indicated times and then fixed with 3.7% formaldehyde and stained using a fluorescent TUNEL assay that specifically detects DNA breaks (see Materials and Methods). Fluorescence intensity of over 10,000 cells was measured by flow cytometry and plotted as histograms. (D) Mutants lacking a variety of published proapoptosis factors were grown in SC medium, treated with 2.5 μg/ml tunicamycin with and without 1 μM FK506, and stained for dead cells using 0.54 μg/ml PI at the indicated times. The average cell death in three independent cultures (± standard deviations) is plotted for each mutant and for the isogenic wild-type (WT) strain. TMR, tetramethylrhodamine fluorescence.