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. 2015 Aug 7;43(20):9729–9741. doi: 10.1093/nar/gkv811

Figure 5.

Figure 5.

GC skew imparts protection against DNA methylation in chordates. (A, B) Promoters were first categorized as possessing, or not, GC skew using novel SkewR annotations (see ‘Materials and Methods' for details). Panel A, reports the percentage of unmethylated promoters in seven vertebrate species for which BioCAP data is available (28). The total number of promoter in each category is indicated at bottom. Panel B reports actual DNA methylation levels in four vertebrate species for which WGBS data is available using a boxplot representation. Median values are shown by a thick line. (C) Promoters were grouped by CpG density (x-axis) and by whether or not they were GC-skewed measured independently of SkewR (see ‘Materials and Methods' for details). The degree of methylation for each promoter group in each species was measured using WGBS data. The data is graphed as boxplots for which the median is shown as a thick line. In panels B and C, P-values were measured by one-tailed Wilcoxon rank-sum statistical test.