title: Activity of aldrinepoxidase, 7-ethoxycoumarin-O-deethylase and 7-ethoxyresorufin-O-deethylase during the development of chick embryos in ovo.
abstract: Since the chick embryo in ovo is susceptible to the action of some agents needing metabolic activation we studied the development of the activity of cytochrome P450-dependent monooxygenases in embryo/fetal tissue. The activities of aldrinepoxidase (AE), 7-ethoxycoumarin-O-deethylase (ECOD) and 7-ethoxyresorufin-O-deethylase (EROD) were measured in whole embryos, liver and yolk sac tissue of the chick embryo during development in ovo from day 4 to day 15 of incubation (DI). In yolk sac tissue enzyme activities could be detected from DI 4 on. While EROD activity was only marginally developed, AE and ECOD activities were more pronounced in the earlier developmental period and showed a clear decrease by the time the liver activities rose. With the methods used AE activity could be measured in the homogenate of the whole embryo proper from DI 4 on while EROD and ECOD activity was not detectable before DI 6 or DI 7, respectively. In liver tissue enzyme activities of the three monooxygenases studied developed to a considerable degree from DI 9 on and tended to exhibit maximum values around DI 11-13. Studies on monooxygenase activities in extra-embryonically located tissues have not been published until now. The importance of the yolk sac as a metabolically relevant organ during embryogenesis is pointed out in this study.
authors.affiliation: Institut für Toxikologie und Embryopharmakologie, Freie Universität Berlin.
authors.forename: B
authors.initials: B
authors.lastname: Heinrich-Hirsch
authors.forename: D
authors.initials: D
authors.lastname: Hofmann
authors.forename: J
authors.initials: J
authors.lastname: Webb
authors.forename: D
authors.initials: D
authors.lastname: Neubert
mesh_terms: D015660:7-Alkoxycoumarin O-Dealkylase / Q000378:metabolism*; D000818:Animals; D002642:Chick Embryo / Q000201:enzymology* / Q000254:growth & development; D019363:Cytochrome P-450 CYP1A1; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D008099:Liver / Q000196:embryology / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D015017:Yolk Sac / Q000201:enzymology
chemical_list: D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; C019647:aldrin epoxidase; D015660:7-Alkoxycoumarin O-Dealkylase; D019363:Cytochrome P-450 CYP1A1