Fig. 2.

Most cell types show increased transcriptional noise with aging. a Boxplot illustrates transcriptional noise by age and cell type for the indicated number of cells. For all boxplots, the box represents the interquartile range, the horizontal line in the box is the median, and the whiskers represent 1.5 times the interquartile range. Blue and red colors indicate young and old cells, respectively. Asterisk indicates significant changes (Wilcoxon’s rank sum test, adjusted p value < 0.05). Cell types are ordered by decreasing transcriptional noise ratio between old and young cells. b Scatterplot shows the log2 ratio of transcriptional noise between old and young samples as calculated using mouse averages (n = 15) and single cells on the X and Y axes, respectively. c Scatterplot depicts the log2 ratio of transcriptional noise between old and young samples as calculated using 1–Spearman correlation and the Euclidean distance between cells on the X and Y axes, respectively. For both panels, the size of the dots corresponds to the negative log10 adjusted p value of the cell type-resolved differential transcriptional noise test and the red lines correspond to the robust linear model regression fit. d As an example, the distribution of 1–Spearman correlation coefficients between all pairs of young and old cells is shown for type-2 pneumocytes. Larger values represent increased transcriptional noise. Blue and red colors indicate young and old samples