Paul Grini Research Group
Most higher organisms inherit DNA from both a mother and a father and the expression of this DNA is equivalent from both male and female genomes. Some genes, however, are only expressed from the maternal or the paternal genome, leaving the non-expressed parent gene completely silenced.This phenomenon is called Genomic Imprinting and is found in higher organisms ranging from plants to humans. Imprinting, typically takes place in the mammalian placenta and in the plant endosperm, but recently it was also shown that several genes expressed in the human brain also are imprinted.
Why are some genes expressed only from one parent?The answer to this is not clear, but a prevailing hypothesis predicts that a parental tug of war on the allocation of available recourses to the developing progeny has led to the evolution of imprinting systems where genes expressed from the mother reduce growth whereas genes expressed from the father are growth enhancers.
What is the mechanistic basis for imprinting? Imprinting is a highly specialized example of epigenetic regulation. Epigenetics involves the modification of DNA and specific amino acid residues in histone tails leading to chromatin rearrangements that allow for or block gene expression.