Figure 3

DNA methylation analysis by bisulfite cloning and sequencing. The analysis was carried out for three species. Cottontail is one of the lagomorphs. Lemming (a rodent) contains fewer CpG sites in the first intron of Impact. Japanese macaque is a primate in which the IMPACT gene is not imprinted. Numbers indicate distances in base-pairs from the 3' end of the first exon. Each row represents an individual cloned allele. Circles represent CpG sites and their spacing reflects the CpG density of the region. Filled and open circles represent methylated and unmethylated sites, respectively. The single nucleotide polymorphism in cottontail fortunately provided allele-specific methylation data, although the parental origin is unknown. Note that this single nucleotide substitution has caused a coexistence of TpG and CpG; only the latter is subject to deamination.