Conservation of Imprinting and Methylation of , and Genes in Cattle.

Genomic imprinting is the epigenetic mechanism of transcriptional regulation that involves differential DNA methylation modification. Comparative analysis of imprinted genes between species can help us to investigate the biological significance and regulatory mechanisms of genomic imprinting. , and are three maternally imprinted genes identified in the human PWS/AS imprinted locus. This study aimed to assess the allelic expression of , and and to examine the differentially methylated regions (DMRs) of bovine PWS/AS imprinted domains. An expressed single-nucleotide polymorphism (SNP)-based approach was used to investigate the allelic expression of , and genes in bovine adult tissues and placenta. Consistent with the expression in humans and mice, we found that the , and genes exhibit monoallelic expression in bovine somatic tissues and the paternal allele expressed in the bovine placenta. Three DMRs, PWS-IC, and DMR, were identified in the bovine imprinted region by analysis of the DNA methylation status in bovine tissues using the bisulfite sequencing method and were located in the promoter and exon 1 of the gene, promoter and 5' untranslated region (5'UTR) of gene, respectively. The PWS-IC DMR is a primary DMR inherited from the male or female gamete, but and DMR are secondary DMRs that occurred after fertilization by examining the methylation status in gametes.