Fig. 3

Graphic representation of pathways enriched by upregulated age-related genes in diaphragm, gastrocnemius, soleus, and tibialis anterior muscles from male mice and rats across multiple ages (from 6 to 27 months). Pathways enriched by linear-up and late-up genes in each muscle (from mice and rats, respectively) are depicted graphically as circles. Each column of circles, for each muscle, corresponds to the comparison between 6 month and the older age (12, 18, 21, 24, and 27 months for mice and 9, 12, 18, 21, 24, and 27 months for rats). The circle size represents the number of age-related genes enriched to each pathway: small circles denote enrichment of the pathway by 0–5 genes; medium circles, enrichment by 6–15 genes and large circles, enrichment by > 15 genes. The circle color indicates the average fold-change in the expression levels of these genes versus 6 months, with the deepest red being an increase of ≥ four fold. Dark squares on the right-hand side of the graphical heatmap indicate that enrichment for a specific pathway was statistically significant