Figure 5. .

mtDNA⁴⁹⁷⁷ deletion mutation in tissue homogenate from aged human skeletal muscle. Total DNA was isolated from skeletal muscle–tissue homogenates of 49-, 60-, 64-, 76-, 83-, and 92-year-old human subjects. To investigate the presence of mtDNA⁴⁹⁷⁷ mutations in skeletal muscle–tissue homogenate at different ages, total DNA was subjected to PCR with primers (F8111–R13756) (table 2A) immediately flanking the deleted region. This deletion mutation was present in all analyzed tissue homogenates. In addition, 57 ETS-normal fibers (fibers that exhibited the COX^normal/SDH^normal phenotype throughout 2,000 μm of analyzed tissue) were randomly selected and analyzed for the presence of mtDNA⁴⁹⁷⁷ from a 49-year-old subject (20 fibers) and from a 92-year-old subject (37 fibers). mtDNA⁴⁹⁷⁷ was not detected in any of these fibers. M = DNA molecular-weight standards; ntc = no template control.