Figure 5. Cell death results from overproduction of mitochondrial ROS.

A, Accumulation of mitochondrial ROS in Fas2Δ/Δ yeast cells after serum treatment. WT and Fas2Δ/Δ yeast cells were treated with 50% serum with or without 1 mM sodium cyanide (NaCN) or 2.5 mM sodium azide (NaN₂) for 24 h at 30°C. Yeast cells were stained with dihydrorhodamine 123 and Sytogreen to visualize ROS and dead cells, respectively. Scale bar: 5 µm. B, Accumulation of ROS coincided with the death of Fas2Δ/Δ yeast cells. The numbers of red (ROS positive) and green (Sytogreen positive) were assessed for Fas2Δ/Δ yeast cells treated for 12 h with serum in the presence or absence of cyanide or azide. C, Inhibition of mitochondrial respiration rescued death of Fas2Δ/Δ yeast cells. Spot assay on YPDT40 of yeast cells incubated with serum in the presence or absence of 1 mM sodium cyanide or 2.5 mM sodium azide. Experiments were performed three times with reproducible results.