FIGURE 8.

Priming stress enhances stress-responsive gene expression under severe stress. A, wild-type (JK317) cells were either not exposed to stress (No stress) or exposed to various stresses: 40 °C for 1 h (Priming stress alone), 25 mm H₂O₂ for 1 h (Severe stress alone), or 40 °C for 1 h followed by 25 mm H₂O₂ for 1 h (Priming stress → Severe stress). Total RNA was analyzed by quantitative RT-PCR using primer sets for stress-responsive genes (ctt1⁺, gpx1⁺, and hsp9⁺) and non-stress-responsive gene (ade6⁺). Values shown were normalized to act1⁺ expression. Results are the means of five independent experiments, and error bars represent S.E. B, fold change of CESR gene expression under three stress conditions compared with no stress condition is plotted for wild-type (JK317) cells. The three stress conditions are as follows: priming stress alone (40 °C for 1 h; 1st), severe stress alone (25 mm H₂O₂ for 1 h 2nd), and priming stress followed by severe stress (40 °C for 1 h followed by 25 mm H₂O₂ for 1 h; 1st+2nd). Horizontal bars represent means of fold change, and mean values are shown below the abscissa axis.