Fig. 3.

Exposure to hyperoxia induces defects in complex IV of the electron transport chain. (A) Electron micrograph of flight muscle (white¹¹¹⁸ strain) showing staining for COX activity. After 6 days under normoxia, mitochondria stain uniformly. (B) After 6 days under hyperoxia, cristae within a swirl are COX deficient (COX^–), whereas cristae in the remainder of the mitochondrion are COX⁺. (C) Electron micrograph of flight muscle from control flies maintained under normoxia and stained with mAb 2G8, which specifically recognizes the apoptogenic cytochrome c epitope. No immunoreactivity is seen. (D) After exposure to hyperoxia for 4 days, the preapoptotic epitope for mAb 2G8 is exposed. (Scale bars indicate 1 μm.)