title: Maturation of the growth axis in marsupials occurs gradually during post-natal life and over an equivalent developmental stage relative to eutherian species.
abstract: The separation of a nutrition-responsive insulin-like growth factor (IGF) system and a growth hormone (GH) responsive IGF system to control pre- and post-natal growth of developing mammals may originate from the constraints imposed by intra-uterine development. In eutherian species that deliver relatively precocial young, maturation of the GH regulatory system is coincident with the time of birth. We measured the hepatic expression of the four key growth axis genes GH-receptor, IGF-1 and -2, and IGFBBP-3, and plasma protein concentrations of IGF-1 from late fetal life through to adult stages of a marsupial, the tammar wallaby. The data clearly show that maturation of GH-regulated growth in marsupials occurs gradually over the course of post-natal life at an equivalent developmental stage to that of precocial eutherian mammals. This suggests that the timing of GH-regulated growth in marsupials is not related to parturition but instead to the relative developmental stage.
authors: ARC Centre of Excellence for Kangaroo Genomics, Department of Zoology, The University of Melbourne, Victoria 3010, Australia. menzies@izw-berlin.de
authors: Brandon R
authors: BR
authors: Menzies
authors: Geoffrey
authors: G
authors: Shaw
authors: Terry P
authors: TP
authors: Fletcher
authors: Andrew J
authors: AJ
authors: Pask
authors: Marilyn B
authors: MB
authors: Renfree
mesh_terms: D000818:Animals; D005260:Female; D005333:Fetus; D018507:Gene Expression Regulation, Developmental; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000235:genetics / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism; D007614:Macropodidae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008297:Male; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011986:Receptors, Somatotropin / Q000235:genetics / Q000378:metabolism*
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D011986:Receptors, Somatotropin; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone