Tumor suppressor gene P53 in fish species as a target for genotoxic effects monitoring

Analysis of environmentally induced molecular changes in DNA from fish was initiated with a study of tumor suppressor gene p53. This gene was chosen because of the high number of documented mutations in p53 from humans and their relevance in tumorigenesis. Bottom-feeding flatfish (e.g. English sole, Pleuronectes vetulus) and members of the salmonid family (e.g. rainbow trout, Oncorhynchus mykiss and chinook salmon, O. tschaaytsha) were chosen, because they are widespread and of commercial and recreational importance. The studies include the use of histopathological, biochemical, and molecular genetic tools in aquatic systems. The authors are currently examining the deposition of DNA damage and mutation in the p53 gene in fish. Parallel histopathology of liver showed idiopathic liver lesions that were strongly dependent on location of capture (0.01 6.89) < 0.025) with a prevalence of 30% for fish collected from the vicinity of pulp mills. To assess DNA damage and mutation analysis, DNA was extracted from fish liver. Polymerase chain reaction (PCR) and DNA sequencing of the p53 gene was performed for rainbow trout, chinook and sockeye salmon, O. nerka. Southern blotting with a labeled p53 probe from rainbow trout was performed using genomic DNA frommore » various teleost fish species. The presence of p53 could be shown in all fish species examined, including salmonids and sentinel species for environmental monitoring like English sole and white sucker (Catostomus commersom). To correlate histopathology with molecular analysis the authors initiated the determination of DNA damage, DNA adducts and mutations in the p53 gene (conserved exons 5 to 9).« less