Research Paper Volume 14, Issue 19 pp 7662—7691

Figure 1. Replicative aging induced mitochondrial dysfunction. (A) Replicative aging activates SA-β-gal. The indicated cells at several passages were stained as SA-β-gal-positive cells (scale bar, 50 μm). (B) Replicative aging induced a genetic aging phenotype. Total RNA was extracted from NB1RGB and IMR90 cells at several passages and subjected to real-time quantitative PCR. Data are presented as the mean ± standard deviation (SD) (three different data sets). (C and D) Replicative aging decreased mitochondrial transmembrane electric potential. The cells were incubated with JC-1 for 20 min and assessed with (C) fluorescence microscopy (red, JC-1 aggregates; green, JC-1 monomers) or (D) microplate reader; ΔΨm was determined by the ratio between the red fluorescence intensity, indicating activated mitochondria, and the green fluorescence intensity, indicating deactivated mitochondria. The data are presented as the mean ± SD of three simultaneously performed experiments (B, D). Each P value was calculated using two-way ANOVA; ^*P < 0.05, ^**P < 0.01.