Molecular Evolution of Mammalian Imprinted Genes: testing the theories Dr Mary J. O’Connell: BME Group, School of Biotechnology, DCU, D9. Ireland.

What are genomic imprints ? One copy is effectively silenced in at least some tissues for a period of the animals life. This silencing depends on the sex of the parent from which the gene is inherited.

What are the theories ? Conflict theory Ovarian Time Bomb Modification of Dominance Nature 1989, Proc Roy Soc Biol 1997, Genetics 1998, PNAS 1998, Nature 2001, Nature Rev Genetics 2001, Nature Genetics 2004 x2, Plos Genetics 2006

Analysis: How have they evolved ? Do genomic imprints have a signature of positive selection as the conflict theory would predict ?

Results:

Conclusion : Genomic imprints in mammals have undergone a haphazard evolution that involved combinations of events: recombination, gene duplication and differential retention and loss, and lineage specific rate variation. A gene duplication and dosage dependency model fits the molecular data best. On measuring selective pressure following genomic imprinting in those lineages for which the imprinting status has been verified only 22% show evidence of positive selection.