Fig. 1

DNA methylation changes correlate with age. a Overview of the Babraham dataset. Ages of the mice are emphasised by colour. Tissues (liver, lung, heart and cortex) were isolated from mice at four distinct time points (newborn, 14 weeks, 27 weeks and 41 weeks). DNA was isolated from these tissues and reduced-representation bisulfite (RRBS) libraries were made. b Heatmap of the top 500 tissue independent age-associated correlations. Highlighted are ages and tissues, CG sites were clustered by Euclidean distance. c Single CG sites within the genome are correlated with age. Shown is an example site (chr8:120397660), with a Spearman correlation with age of 0.65. Tissues are highlighted by colour. Jitter is for aesthetic purposes only. d Overview of Spearman correlations calculated over all tissues. The distributions of correlation estimates are shown in the histogram and proportionate numbers of correlations are shown in the bar plot. Nominal correlations are highlighted (p value < 0.05) in light orange (positive) and light blue (negative). Significant correlations are highlighted (q-value < 0.05) in orange (positive) and blue (negative). Numbers provided above the bar plot represent the number of single CG sites within the given category. e Surrounding CpG content (± 500 bp) of the significantly correlated sites. Background was calculated from all CG sites with five-fold coverage in 90% of samples; CpG scarcity is defined as the average CpG distance within this 1 kb region. *Bonferroni corrected p value < 0.05. f Enrichment of a correlated CG site falling within a given genomic element. Background was all CG sites with five-fold coverage in 90% of samples. Tested using binomial test; *p value < 0.05. g Gene Ontology (GO) analysis of the significantly correlated CG sites. GO terms are plotted against –log(corrected p value). Positive correlations are shown in orange and negative in blue. The six most significant GO terms are shown. h Tissue-specific Spearman correlations with age. An example is provided of a tissue-specific correlation with age in cortex, liver, lung and heart. Correlations for these CG sites are provided for all tissues combined and for the tissue in question. Jitter is for aesthetic purposes only