Assessment of the genotoxic hazard of estuarine sediments using an integrative approach with LacZ Plasmid-Based transgenic mice

Under the influence of multiple anthropogenic pressures, from industrial to agricultural activities, estuaries have long been regarded as particularly sensitive ecosystems to contamination. The present study aimed at investigating the genotoxic potential of a contaminated sediment sample from an urban and industrial area of the Sado Estuary, by combining the analysis of multiple endpoints in the LacZ plasmid-based transgenic mouse model exposed for 28 days to contaminated estuarine sediment extracts through drinking water. The DNA and chromosome damaging effects were monitored in peripheral blood at 7-day intervals using the standard and enzyme-modified Comet assay, as well as the micronucleus assays in peripheral blood cells. After euthanasia, DNA damage was analyzed in several mouse tissues, and LacZ mutant frequencies were determined in the liver. Livers were also surveyed for histopathological analysis. A time-dependent increase in micronuclei frequency was seen at all tested doses, in spite of no induction of DNA damage in any organ or mutation induction in the liver of exposed mice. The liver from mice exposed to sediment extracts did not reveal major alterations besides evidence of inflammation. Overall, the integration of the endpoints analyzed in the mice is suggestive of potential chronic, rather than acute, adverse effects in vivo, and points to the need for further research in the resident human population in the area. This experimental design can be used to assess the genotoxicity of complex environmental mixtures, understand how they work, and reduce costs and resources while speeding up data collection and interpretation.