title: Temperature-modulated aflatoxin B1 hepatic disposition and formation and persistence of DNA adducts in rainbow trout.
abstract: Previous work showed that the incidence of chemically induced tumors in fish increased with environmental temperature. The present study assessed genotoxicity as a mechanism to explain such results. Rainbow trout (2 g) were acclimated to 10 or 18 degrees C for 1 month and then immersed in 0.1 ppm [3H]aflatoxin B1 (AFB1) solutions for 30 min at their respective acclimation temperatures, or at 14 degrees C. The total radioactivity in liver immediately after immersions was 50% higher for 18- than 10 degrees C-acclimated and exposed fish. Conversely, adduction of [3H]AFB1 to hepatic DNA of 10 degrees C-acclimated fish was higher than that of 18 degrees C-acclimated fish after exposure. A similar DNA adduction result was observed after [3H]AFB1 immersion concentrations were varied to achieve similar hepatic [3H]AFB1 equivalents. After acute shifts in temperature (10 to 14 degrees C or 18 to 14 degrees C), no differences were found in hepatic [3H]AFB1 equivalents. However, adduction of [3H]AFB1 to hepatic DNA was higher for 10- than for 18 degrees C-acclimated fish 1 day after exposures at 14 degrees C. This was probably explained by effects of temperature acclimation on the status of the membrane-bound cytochrome P-450 system, affecting its competition with a detoxifying cytosolic enzyme. After [3H]AFB1 immersions at respective acclimation temperatures, or acute temperature shifts to 14 degrees C, DNA adducts were less persistent in fish maintained for 21 days at 18 degrees C than at 10 degrees C. Our data demonstrated that temperature-modulated AFB1 genotoxicity occurred via three mechanisms: hepatic disposition and formation and persistence of DNA adducts.
authors.affiliation: Oak Creek Laboratory of Biology, Oregon State University, Corvallis 97331.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
authors.forename: K
authors.initials: K
authors.lastname: Suorsa-Super
authors.forename: L R
authors.initials: LR
authors.lastname: Curtis
mesh_terms: D016604:Aflatoxin B1 / Q000378:metabolism* / Q000493:pharmacokinetics; D000818:Animals; D001822:Body Burden; D004247:DNA / Q000378:metabolism*; D006358:Hot Temperature; D008099:Liver / Q000378:metabolism*; D014337:Trout
chemical_list: D004247:DNA; D016604:Aflatoxin B1