Oxidative stress in str4Δ in the presence of homocysteine and its precursors. A, heat map of up-regulated oxidative stress response genes in the presence of homocysteine and its precursors was generated using Multiexperiment viewer software (MeV version 4.0b). B, flow cytometry measurement of ROS-positive cells. Yeast cells exposed to various conditions for 16 h or hydrogen peroxide for 1 h were harvested and incubated with DHE for 1 h and analyzed by Guava EasyCyte Flow cytometer. Error bars are representative of means ± S.D. (n = 3). C, fluorescence microscopy images were acquired using inverted Nikon epifluorescence microscope in similar experimental conditions. SAM, AdoMet; SAH, AdoHcy; CON, control.