Fig. 3

Mitochondrial accumulations in gastrocnemius muscles of mutant mice. Transverse sections (15 μm thick) from the gastrocnemius muscles of 8 month old mice and H&E staining (a), NADH-TR staining (b), SDH staining (c) and an ATPase staining (d) showed no apparent difference between genotypes. Scale bars: 50 μm. e Accumulation of mitochondria in the gastrocnemius muscles of mt/mt in comparison to wt mice determined by electron microscope (EM). Scale bar: 500 nm. f Real-time PCR was used to evaluate mtDNA copy numbers of COX IV (cytochrome c oxidase subunit 4) from the muscle of knock-in mice. The COX IV is significantly elevated in mt/mt mice in comparison to wt and wt/mt mice. COX IV is represented as a mitochondrial gene relative to the levels of β-actin, a nuclear DNA (nDNA)-encoded gene (n = 3, ***P<0.001)