Assessment of environmental stress by the micronucleus test and the Comet assay on the genome of teleost populations from two natural environments.

The aim of the present paper was to assess the biological damage caused by exposure of the test organism (Gambusia holbrooki: Cyprinodontiformes, Poecilidae) to various mutagenic agents present in the polluted waters of the Sarno River. For this purpose, we performed a micronuclei (MN) test and single cell gel electrophoresis (the Comet assay), testing DNA migration in an electrophoretic field using erythrocytes of G. holbrooki specimens both from the Sarno River and from the waters of the crater of the Astroni natural reserve as negative controls. The results indicate statistically higher values for both MN and DNA migration in the samples from the Sarno River compared with those from Astroni and point to a strong genotoxic action of the mixture of pollutants present in the Sarno River. These data were compared with the values found in the G. holbrooki specimens from the Sarno River kept under laboratory conditions for 100 days in clean water.