title: Post-natal imprinting: evidence from marsupials.
abstract: Genomic imprinting has been identified in therian (eutherian and marsupial) mammals but not in prototherian (monotreme) mammals. Imprinting has an important role in optimising pre-natal nutrition and growth, and most imprinted genes are expressed and imprinted in the placenta and developing fetus. In marsupials, however, the placental attachment is short-lived, and most growth and development occurs post-natally, supported by a changing milk composition tailor-made for each stage of development. Therefore there is a much greater demand on marsupial females during post-natal lactation than during pre-natal placentation, so there may be greater selection for genomic imprinting in the mammary gland than in the short-lived placenta. Recent studies in the tammar wallaby confirm the presence of genomic imprinting in nutrient-regulatory genes in the adult mammary gland. This suggests that imprinting may influence infant post-natal growth via the mammary gland as it does pre-natally via the placenta. Similarly, an increasing number of imprinted genes have been implicated in regulating feeding and nurturing behaviour in both the adult and the developing neonate/offspring in mice. Together these studies provide evidence that genomic imprinting is critical for regulating growth and subsequently the survival of offspring not only pre-natally but also post-natally.
authors.affiliation: 1] Centre for Genetic Diseases, Monash Institute of Medical Research and Prince Henry's Institute, Clayton, Victoria, Australia [2] Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia [3] Department of Zoology, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: J M
authors.initials: JM
authors.lastname: Stringer
authors.affiliation: 1] Department of Zoology, The University of Melbourne, Melbourne, Victoria, Australia [2] Department of Molecular and Cellular Biology, The University of Connecticut, Storrs, CT, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Pask
authors.affiliation: Department of Zoology, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: G
authors.initials: G
authors.lastname: Shaw
authors.affiliation: Department of Zoology, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: M B
authors.initials: MB
authors.lastname: Renfree
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D005075:Biological Evolution; D019175:DNA Methylation; D005260:Female; D005786:Gene Expression Regulation; D018392:Genomic Imprinting; D006801:Humans; D008297:Male; D008321:Mammary Glands, Animal / Q000378:metabolism; D008394:Marsupialia / Q000235:genetics*; D008957:Models, Genetic; D011247:Pregnancy