Genes Dev. 22, 1141–1146 (2008) 10.1101/gad.473408

Cells 'tag' newly synthesized RNA with tails of repeating units of adenine in order to make the RNA molecule more stable and prepare it for life in the cytoplasm.

Rebecca Oakey of King's College London and her colleagues report that, for a particular mouse gene, the choice of tagging site correlates with the extent to which the relevant DNA carries methyl groups. This methylation is a form of 'epigenetic imprinting' — a propensity for a particular copy of a gene to be expressed or not that is, itself, inherited.

This is the first evidence that epigenetic imprinting can affect the composition of RNA transcripts in this way.