Figure 1.

Time course at 30 minute intervals in cells from stationary phase cultures exposed to 50 μM menadione. (a) Heat map of results from unsupervised, hierarchical clustering (Pearson's centered, average-linkage) of approximately 2,800 transcripts. Microarrays were of samples taken at 30 minute intervals over 8 hours. The color scale at the bottom indicates the log₂ values of changes in mRNA abundance. (b) Median values for the four major temporal patterns of gene expression identified on the right side of the heat map in (a). RNA was isolated using the modified Gentra method described in Materials and methods.