Figure 3.

Cytochrome c oxidase assay. The activity of cytochrome c oxidase was measured as the reduction in absorbance at 550 nm, a characteristic wavelength for ferrocytochrome c. Cytochrome c oxidase activity was significantly reduced because of MT-CO1 downregulation in the RRCs (*P=0.023). Although cytochrome c oxidase activity was increased in both the parent and RRCs after 5-Gy irradiation, it was significantly lower in the RRCs (^#P=0.005). Error bars represent the standard deviation of the mean. MT-CO1, cytochrome c oxidase 1; RRCs, radioresistant cells.