Promoter CpG methylation profiles at X-linked escaper and non-escaper genes. (A–C) Bisulfite sequencing of the promoter CpG islands for an escaper gene Flna (A) and two non-escaper genes, Ocrl (B) and Ids (C), in opossum female fetal brain and EEM showing the absence of promoter methylation in these tissues. Each panel depicts replicate alignments of multiple CpG sites at the promoter for the corresponding gene/tissue. (Yellow boxes) Methylated CpGs; (blue boxes) unmethylated CpGs. A SNP in the Flna promoter (red and green boxes) enabled transmission direction and methylation on each allele to be inferred; the maternal allele is G (green boxes), and the paternal allele is A (red boxes). (D) Profile of promoter CpG island methylation status in five escaper genes (labeled in blue), 17 non-escaper genes (in red), and Rsx (in orange) using the PyroMark assay in female and male fetal brain and EEM samples. (Red bars) The methylation percentage (0%–100%) at one promoter CpG site in the corresponding CpG island.
