Genotypic mutation analysis in the p53 gene of benzo[a]pyrene-treated European flounder (Platichthys flesus)

We have applied a genotypic mutation detection system (the Restriction Site Mutation (RSM) assay) to detect mutations in the marine teleost flounder ( Platichthys flesus). The aim of this study was to evaluate this species as an environmental indicator of genotoxic exposure. We have used the model ge notoxin benzo[a]pyrene (B[a]P) to determine the limits of mutation detectio n in the p53 gene of flounder liver DNA, This study has revealed two import ant findings, Firstly, we were able to demonstrate that a polymorphism exis ts in the TaqI restriction site of exon 8 of the flounder p53 gene at codon 243, This polymorphic allele was present as a heterozygote at a mean frequ ency of 15%, whereas 85% carried the homozygous wild type sequence, Secondl y, we established that B[a]P treatment resulted in specific mutational even ts at the adenine base of the same TaqI site, contrasting previous reports stating that there was a guanine preference for this chemical in mammalian DNA. This difference in mutation specificity may possibly be accounted for by sequence specific factors or by species differences in metabolic activat ion and/or DNA repair and are worthy of further study. (C) 2000 Elsevier Sc ience B,V. All rights reserved.