BY4730 cultures were exposed to medium containing dilutions of test agent (Cisplatin (Cis), 600mg/mL; Methylmethane sulfonate (MMS), 0.12% v/v; Bleomycin (Bleo), 0.15U/mL; NaCl, 10mg/mL; ethanol, 15% v/v) for 120 min. Control cultures were either mock-treated with the solvent, DMSO (for comparison to Cis, MMS, Bleo) or maintained in media (for comparison to ethanol and NaCl) for 120 mins. Sample preparation and processing procedures were performed according the Affymetrix Genechipâ Expression Analysis Technical Manual (Affymetrix, Santa Clara, CA). Briefly, total RNA was isolated from thawed cell pellets using a hot phenol protocol described by Schmitt et. al. (1990). Total RNA was converted to poly(A)+ mRNA and isolated using Oligotex mRNA kit. Double stranded cDNA was generated by using T7-(dT) 24 oligo primer (Genset Corp., San Diego, CA) and Superscript Double Stranded cDNA Synthesis Kit (Gibco BRL, Carlsbad, CA). The cDNA was used for in vitro transcription (IVT) with Enzo BioArray RNA Transcript Labeling Kit to incorporate biotinylated ribonucleotides. Biotinylated cRNA (15 mg) was fragmented in 40 mM tris-acetate, pH 8.1; 30 mM MgOAc; 100 mM KOAc. Samples were then hybridized with Affymetrix probe array Yeast Genome S98 at 45°C for 16 hours with constant rotation. Hybridized probe arrays were washed and stained using an Affymetrix GeneChipâ Fluidics Station 400 and protocol EukGE-WS2. The chips were scanned using the Affymetrix GeneArray Scanner.
