Temperature-modulated aflatoxin B1 hepatic disposition and formation and persistence of DNA adducts in rainbow trout.
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.
Zhang
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Oak Creek Laboratory of Biology, Oregon State University, Corvallis 97331.
Suorsa-Super
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Curtis
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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
D004247:DNA; D016604:Aflatoxin B1