Figure 5

NQM1 mRNA expression is dependent on osmolarity. A) Osmolality was determined in triplicates by freezing-point depression. The grey bar at 233.75mOsmol/kg refers to the synthetic complete media osmolality prior to the experiment. All yeast strains depict a high osmolality at the start of the experiment which decreases during the chronological ageing below the control value (blank media) and remains stable until the end of the aging. Wild type (WT) and Δnqm1 cells show a similar trend, whereas the decrease is stronger in the double mutant and diminished in Δvhr1. B) + C) mRNA expression of NQM1 during the osmotic stress response in wild type and Δvhr1 mutant yeast. Time courses of NQM1 were generated by quantitative real-time-polymerase chain reaction (qRT-PCR) in wild type and Δvhr1 yeast treated with NaCl or sorbitol for 0, 0.5, 1, and 2 hours. Upon NaCl treatment, NQM1 was severely induced in both wild type and Δvhr1 mutant yeast (Figure 5B). Upon sorbitol treatment, the induction pattern of NQM1 was similar in wild type and Δvhr1 mutant yeast, albeit the magnitude in the Δvhr1 mutant was reduced (Figure 5C). All experiments were performed in triplicates. Samples for qRT-PCR have been generated in liquid media containing glucose (2%) as sole carbon source. NaCl, sorbitol was added to induce osmotic shock upon cells reached mid-log phase (OD₆₀₀ = 0.8-1.0). Error bars, ± SD.