Figure 1

Examination of the mitochondrial theory of aging by using human fibroblast lines derived from young and elderly subjects. The ‘young’ group included fibroblast lines TIG3S (fetus), TIG121 (age 8 months [8mo]), TIG120 (6 years [6y]) and TIG118 (12 years [12y]). The ‘elderly’ group included fibroblast lines TIG106 (80 years [80y]), TIG107 (81 years [81y]), TIG101 (86 years [86y]) and TIG102 (97 years [97y]). (a) Comparison of mitochondrial respiratory function between young and elderly groups by estimation of O₂ consumption rates. ‘Average’ indicates the average O₂ consumption rates of each group. (b) Comparison of amounts of mitochondrial ROS (superoxide) between young and elderly groups by estimation of mitochondrial superoxide levels. Relative superoxide levels are expressed as mean fluorescence intensity of MitoSox-Red. ‘Average’ indicates the average fluorescence intensity of each group. Experiments in (a) and (b) were performed in triplicate; error bars, ± SD. *P < 0.05. Black and open bars represent young and elderly groups, respectively. (c) Comparison of mutation frequencies in mtDNA populations from young and elderly groups by using deep sequence analysis. Upper, middle and lower panels represent frequencies of total, rare and frequent mutations, respectively. Rare mutations existing in less than 1% mtDNA correspond to somatic mutations, whereas frequent mutations existing in 1% or more of mtDNA correspond to inherited mutations. Black and open circles represent young and elderly groups, respectively.