Unmethylated endogenous retrovirus copies may act as promoters for host genes. RT-PCR was performed on cDNA samples from tissues where the ERV studied is unmethylated, using primers targeting the ERV and either the first or the second gene exon (see Materials and methods). cDNAs are represented by flat lines (sequenced cDNA) and black dashed lines (inferred introns). Genes are in blue, intergenic regions in black and ERV sequences in red. Allelic expression of Cyb5r1 in hybrids is shown as a pie-chart. Hybrids containing one allele with the ERV copy (white) and one allele without it (black), were subjected to allelic expression quantification via single nucleotide polymorphisms (see Materials and methods). bp: base pairs; CGI: CpG Island; ERV: endogenous retrovirus; LTR: long terminal repeat; PCR: polymerase chain reaction; RT: reverse transcriptase.
Rebollo et al. Genome Biology 2012 13:R89 doi:10.1186/gb-2012-13-10-r89