FIG 4.

Simultaneous overexpression of the SOD1, SOD2, and CTT1 genes protects S. cerevisiae cells from oxidative and photocatalytic treatment. The wild-type S. cerevisiae BY4742 strain without plasmids (WT; left panel) and BY4742 transformants bearing three multicopy plasmid expressing antioxidant SOD1, SOD2, and CTT1 genes (right panel) were incubated in the presence of 2.5 mM H₂O₂ or UV-A-illuminated TiO₂. At the indicated time points, 100 μl of cell suspension was 10-fold serially diluted, and 10 μl of each dilution was spotted onto YPD medium. Plates were incubated 3 days at 30°C before being photographed.