Genomic expression programs in the response of yeast cells to environmental changes

We explored genomic expression patterns in the yeast Saccharomyces cerevisi ae responding to diverse environmental transitions. DNA microarrays were us ed to measure changes in transcript levels over time for almost every yeast gene, as cells responded to temperature shocks, hydrogen peroxide, the sup eroxide-generating drug menadione, the sulfhydryl-oxidizing agent diamide, the disulfide-reducing agent dithiothreitol, hyper- and hypo-osmotic shock, amino acid starvation, nitrogen source depletion, and progression into sta tionary phase. A large set of genes (similar to 900) showed a similar drast ic response to almost all of these environmental changes. Additional featur es of the genomic responses were specialized for specific conditions. Promo ter analysis and subsequent characterization of the responses of mutant str ains implicated the transcription factors Yap1p, as well as Msn2p and Msn4p , in mediating specific features of the transcriptional response, while the identification of novel sequence elements provided clues to novel regulato rs. Physiological themes in the genomic responses to specific environmental stresses provided insights into the effects of those stresses on the cell.