2.6. PCR-Based Analysis of mtDNA/nDNA Ratio

The mitochondrial DNA (mtDNA) concentration was analyzed quantitatively between a target mitochondrial gene and a reference nuclear gene (mtDNA/nDNA) using quantitative real-time PCR (qPCR), as described previously. Briefly, mtDNA/nDNA ratios were measured by quantifying the number of mtDNA molecules per nDNA molecule calculated by the classical ΔΔCt method used for qPCR analysis using the following primers: mitochondrial NADH-ubiquinone oxidoreductase chain 1 (mt-ND1) forward: 5′-CCGTCCTCCTAATAAGCGGC-3′ and mt-ND1 reverse: 5′-TATGGCTATTGGTCAGGCGG-3′; GADPH forward: 5′-CCCCCAATGTATCCGTTGTG-3′ and GAPDH reverse: 5′-TAGCCCAGGATGCCCTTTAGT-3′.