Induction of Erythrocytic Nuclear Abnormalities by Permitted Concentration оf Cadmium in Common Carp (Cyprinus carpio L.)

The induction of micronuclei and other nuclear abnormalities (NAs) - nuclear buds, nucleoplasmic bridges, binucleated cells, as well as notched, blebbed, lobed and eight-shaped nuclei - was analyzed in peripheral blood erythrocytes of common carp (Cyprinus carpio L.) treated with cadmium (Cd) at legally allowed concentration. Young specimens of the common carp were exposed to the lowest of the four permitted concentrations of Cd (0.45 μg/L) in surface waters, according to Directive 2013/39/EU, for 72 h and 144 h in laboratory conditions. Blood smears were stained with acridine orange and tested for the presence of micronuclei and other NAs. We report that Cd exposure for 72 h resulted in a significantly increased number of blebbed and lobed nuclei and eight-shaped nuclei, as well as an increase in the frequency of Total NAs. Cd exposure for 144 h resulted in an increase in the number of cells with notched nuclei and nucleoplasmic bridges, as well as an increased occurrence of binucleated cells. Our results highlight the cytotoxic and genotoxic effects of Cd, even at low permissible levels, and confirm the use of NAs as an effective biomarker. The elevated levels of NAs observed after just 144 h of exposure to Cd highlight the need for further research. Once confirmed, changes in national and EU legislation of permitted concentrations of Cd in surface waters might be required.