highly significantP = 1.9 × 10 −3
Further, methylation differences between old and young ages were highly significant, with methylation at most elements decreased in old age ( t -test P = 1.9 × 10 −3 for H strand and 1.4 × 10 −4 for L strand) ( Fig. 3 B). mtDNA methylation negatively correlates with mitochondrial gene expression Although mtDNA is transcribed in a polycistronic fashion, mRNA levels of individual genes differ substantially, reflecting differences in processing, stability, or turnover of each mRNA ( Supplemental Fig.