DNA methylation profiles of three CpG regions in bovine RTEL. Three regions of CpG island were chosen for DNA methylation analysis, CpG region 1 (R1) and 2 (R2) are located in promoter region and CpG region control (RC) is in exon 2 and intron 2. A. Relative positions of three CpG regions be analyzed. Position of the islands are indicated by thick lines on the top, related genomic region and ATG site are indicated by boxes and arrow (not to scale), exon1 and exon1' mean alternative first exon and the arrows bellow indicate two putative transcription start sites. B. DNA methylation profile of the three selected regions. The cycles in a string mean the average methylation level of specific sites in each CpG region, the numbers above indicate the relative position of each CpG dinucleotides. Analyzed tissues (testis, spleen and heart) are indicated on the left. For the convenience to compare, CpG regions in the promoter regions (R1 and R2) and internal region are show separately. In each string, the open cycles indicate that the CpG sites are hypomethylated in all the clones that analyzed whereas closed cycles mean fully methylated CpG dinucleotides, other partially blacked cycles indicate different methylation level, details are shown in the right of the bottom. The average methylation level was calculated by sequencing ten individual clones of the PCRs. Besides the methylation level of each CpG sites, the percentages of DNA methylation in the indicated region of the CpG regions are also shown on the right (the data of R1 and R2 are incorporated to represent the methylation level of the promoter region). Only differential methylated CpG sites in three detected CpG regions are shown in the figure.