title: Age dependence of O6-methylguanine-DNA methyltransferase activity and its depletion after carcinogen treatment in the teleost medaka (Oryzias latipes).
abstract: O6-Methylguanine-DNA methyltransferase (O6-MT) is considered to play an important role in the repair of DNA lesions induced by alkylating carcinogens in a wide range of animals. The activity of O6-MT was compared in liver extracts from the teleost medaka (Oryzias latipes) at various ages (3-5 years old) reared under natural conditions. O6-MT activity decreased significantly with advancing age. When medaka were exposed continuously to the alkylating agent methylazoxymethanol (MAM) acetate at levels of 0.1, 0.15 and 0.3 ppm in water, O6-MT activity was markedly reduced from days 1 to 7, with a slight increase thereafter. Furthermore, when fish were exposed to MAM acetate at levels of 1-2 ppm for 1 h and then maintained in normal tap water, O6-MT activity remained suppressed for 2 weeks, followed by a partial recovery.
authors.affiliation: Division of Biology, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Aoki
authors.forename: Y
authors.initials: Y
authors.lastname: Nakatsuru
authors.forename: J
authors.initials: J
authors.lastname: Sakurai
authors.forename: A
authors.initials: A
authors.lastname: Sato
authors.forename: P
authors.initials: P
authors.lastname: Masahito
authors.forename: T
authors.initials: T
authors.lastname: Ishikawa
mesh_terms: D000375:Aging / Q000378:metabolism*; D000477:Alkylating Agents / Q000494:pharmacology*; D000818:Animals; D002273:Carcinogens / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D008099:Liver / Q000201:enzymology; D008746:Methylazoxymethanol Acetate / Q000031:analogs & derivatives* / Q000494:pharmacology; D008780:Methyltransferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019853:O(6)-Methylguanine-DNA Methyltransferase; D009990:Oryzias
chemical_list: D000477:Alkylating Agents; D002273:Carcinogens; D008746:Methylazoxymethanol Acetate; D008780:Methyltransferases; D019853:O(6)-Methylguanine-DNA Methyltransferase; C030667:methylazoxymethanol