Figure 3. A steep change in the transcriptome of skeletal muscle during the late phase of aging. (A, D) Principal component analysis of the skeletal muscle (A) and peripheral blood mononuclear cell (PBMC); (D) RNA-seq data from 2-, 10-, 18-, 24-, and 28-month-old mice. Transcriptomes of different age groups are marked by different colors. The curved orange arrow connects the group mean transcriptome of each age group to show an age-associated change in the gene expression profile of the skeletal muscle. Box plots show the distribution of normalized counts. (B, E) Measurement of the group mean transcriptomic distance / variance of each age group, relative to the 2-month group (numbers in black) or among the age groups (numbers in blue). (C, F) Per-month differentiation of transcriptomes between the age groups, which divides the transcriptomic distance by the age (month) difference.