DNA damage in the freshwater fish Australoheros facetus acutely exposed to imidacloprid: possible explanation through an oxidative mechanism

SIMONIELLO FERNANDA; MENDIETA JULIETA; ITURBURU FERNANDO GASTÓN; PANZERI ANA

Santos

Congreso; XII Congreso SETAC Latinoamerica; 2017

Society of Environmental Toxicology and Chemistry

The presence of neonicotinoid insecticides in a wide type of environments around the world and its possible negative effects in non- target organisms are important topics in environmental risk assessment. Particularly, there is a large amount of reports about imidacloprid (IMI) presence in freshwater bodies, and its effects on aquatic invertebrates. Nevertheless, negative effects in freshwater fish are usually limited to mortality endpoints, and there is a lack of information about sublethal effects in this taxon. Hence, the objective of this work was to evaluate genotoxic effects and oxidative damage of the Southamerican fish Australoheros facetus exposed to environmental concentrations of IMI. Fish were exposed in an acute experiment for 48 h to 1, 10, 100 and 1000 g/ L IMI. DNA damage through the Micronucleus (MN) and the Comet assays were performed in blood cells, the last with ENDO III enzyme modification to detect pyrimidine bases oxidation. Lipid and protein oxidation were quantified in liver, brain and gills.DNA damage through the MN frequency was evidenced at 1000 g/ L, while with the comet assay- damage index this effect was observed at 100 and 1000 g/ L. Moreover, an increase of ENDO III sites at all IMI concentrations tested was observed. Lipid peroxidation was detected at 100 g/ L IMI in gills as well as at 1000 g/L IMI in brain. These results show that a process of DNA bases oxidation occurs from low IMI concentrations, and at high IMI concentration there is DNA fragmentation too. Therefore, these results suggest that the possible mechanism of DNA damage could start with an oxidation process, leading to DNA fragmentation. Comparatively, comet assay was a more sensitive tool than MN frequency to evaluate DNA damage. In addition, lipid peroxidation in gills and brain alert about possible sublethal effects like oxidative damage induced by IMI in different key tissues of fish. These negative effects must be taken into account as possible endpoints in ecological risk assessment of IMI in freshwater bodies, mainly because DNA damage could trigger other effects at organism or population levels.