Human Genome Center; Institute of Medical Science, University of Tokyo
A novel systematic screening method termed the Allelic Message Display (AMD) was developed for the hunting of imprinted genes. In AMD, differential display PCR is adopted to image allelic expression status of multiple anonymous polymorphic transcripts in two parental mouse strains, their reciprocal F1 hybrids and pooled backcross progenies. From the displayed patterns, paternally and maternally expressed transcripts can be unequivocally identified. The power of AMD screening was demonstrated by the identification of a novel paternally expressed gene Impact on mouse chromosome 18. In contrast with other screening methods necessitating positional cloning efforts or special starting materials (e.g. parthenogenetic and androgenetic embryos), AMD approach requires nothing particular but appropriately crossed animals. Furthermore, it can be readily applied to any tissues at any developmental stages, and thus would be particularly useful for the identification of genes whose imprinting are tissue-specific or established in later stages of the development.