title: Ontogenic expression of detoxication enzymes in an Australian marsupial, the brushtail possum (Trichosurus vulpecula).
abstract: Marsupials and eutherians display vastly different reproductive strategies. Marsupials are characterised by the production of altricial neonates with little functional capacity. An investigation of the ontogenic expression of phase I (mixed function oxidase) and phase II (glutathione transferase) enzyme systems in the marsupial, the brushtail possum was undertaken. Enzyme expression in the youngest age group studied (60 days old) was between 5% and 10% of the adult level. A gradual increase in expression was then observed until a significant 3-fold increase to adult levels of expression of cytochrome P450, cytochrome b5 and glutathione transferase content and ECOD and AE activity was observed in brushtail possum young between the ages of 150 +/- 15 and 180 +/- 15 days. The expression of EROD activity reached adult levels by the age of 150 +/- days, while the expression of NADPH-cytochrome c reductase activity was delayed and adult levels had not yet been achieved by the oldest group studied (> 200 days). The ontogenic expression of detoxication enzymes was significantly delayed in the marsupial in comparison to eutherians. Adult levels were achieved during the weaning period, suggesting that dietary xenobiotics act as a regulatory mechanism in the developmental expression of these enzymes in the brushtail possum.
authors.affiliation: Key Centre for Applied and Nutritional Toxicology, RMIT-University, Melbourne, Vic., Australia.
authors.forename: R M
authors.initials: RM
authors.lastname: Bolton
authors.forename: J T
authors.initials: JT
authors.lastname: Ahokas
mesh_terms: D015660:7-Alkoxycoumarin O-Dealkylase / Q000378:metabolism; D000452:Aldrin / Q000378:metabolism; D000818:Animals; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D015786:Cytochromes b5 / Q000378:metabolism; D005260:Female; D005982:Glutathione Transferase / Q000302:isolation & purification / Q000378:metabolism; D008658:Inactivation, Metabolic; D008099:Liver / Q000201:enzymology / Q000254:growth & development; D008297:Male; D006899:Mixed Function Oxygenases / Q000378:metabolism; D009893:Opossums / Q000254:growth & development* / Q000378:metabolism*; D015262:Xenobiotics / Q000378:metabolism*
chemical_list: D015262:Xenobiotics; D015786:Cytochromes b5; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D015660:7-Alkoxycoumarin O-Dealkylase; D019363:Cytochrome P-450 CYP1A1; D005982:Glutathione Transferase; D000452:Aldrin