Comparative mutagenicity of aflatoxins using a Salmonella/trout hepatic enzyme activation system

A modification of the Ames assay using rainbow trout (Salmo gairdneri) liver postmitochondrial fraction (PMF) was developed to investigate the relative mutagenic potential of a series of aflatoxins (AFs). Preliminary experiments revealed that the 20000 x g (S20) liver fraction contained a higher metabolic activity than either the S9 or S30 fractions, and that 5 mg of S20 protein/plate gave the highest mutagenic response. A 9-24 h preincubation period at 25 degrees C was also required. The results from comparative mutagenicity experiments showed the following relative potencies: AFB1 greater than AFL greater than AFG1 greater than AFM1 greater than AFB2 greater than AFP1 greater than AFQ1. The relative potencies observed with this in vitro system qualitatively correlated with the in vivo carcinogenic activity seen in trout, indicating that this assay is of value in predicting the carcinogenic potential of mycotoxins in this species.