Differential methylation at the H19/IGF2 ICR in bovine . Top. The putative H19/IGF2 ICR is drawn to scale and depicted in light purple. Arrow mark the start and direction of H19′s transcription. The region amplified by the bisulfite specific primers is represented by a yellow box and encompasses a putative CTCF site. Putative CTCF sites were determined using the University of Essex CTCF searching database (http://www.essex.ac.uk/bs/molonc/binfo/ctcfbind.htm) and are depicted by black vertical lines. From left to right CTCF site 1(cgttaagggg – located at −4739 to −4749 bp from H19′s transcription start site). CTCF2 (ccgcgaggcggcag −4311 to −4325 bp), CTCF3 (ccgcggggcggcgg −3882 to −3896 bp), CTCF4 (cgttaagggg −3372 to −3382 bp), CTCF5 (ccgcgaggcggcag −2944 to −2958 bp), CTCF6 (tggacagggg −1739 to −1749 bp), CTCF7 (ccgcgaggcggcgg −1492 to −1506 bp), CTCF8 (tgttgagggg −251 to −261 bp). Bottom. Shown is an example of bisulfite sequence data from an F1 individual. The bisulfite converted DNA was amplified and cloned prior to sequencing. Each line of circles represents individual alleles. Open circles represent unmethylated CpGs and closed circles represent methylated CpGs. Female symbol = maternal alleles, male symbol = paternal alleles. The position of the SNP used to differentiate between B. t. indicus and B. t. taurus alleles is shown by an arrow.