Figure 9.

Cells with the cit1 deletion exhibit depletion of GSH, which leads to increased susceptibility to heat-induced and ROS-mediated apoptosis. (A) Effect of exogenous GSH on the ts phenotype caused by the deletion of CIT1. Yeast strains (wild type, Δcit1, Δcit2, and Δcit1Δcit2) were grown in SCD broth with or without 10 mM GSH, and then they were incubated at 50°C for 10 min. Aliquots of the samples were taken, and surviving cells were evaluated by CFU assays carried out in triplicate. (B) Effect of exogenous GSH on ROS accumulation in CIT1-deleted cells exposed to heat stress. The yeast strains listed above were grown in SCD with or without 10 mM GSH, and then they were incubated at 50°C for 10 min. The cells were then stained with DCFH-DA and examined by fluorescence microscopy. The numbers of DCFH-DA–positive cells were estimated in fluorescence images and total cells in corresponding DIC images.