Effect of cadmium on hematological functions in tilapia (Oreochromis mossambicus)

Assessment of water quality and genotoxic impact by toxic metals in Geophagus brasiliensis

This study used the pearl cichlid Geophagus brasiliensis as a bioindicator to survey the health of the aquatic environment on four sites (P1, P2, P3 and P4) of the Mumbuca stream located at Monte Carmelo/MG, Brazil. The selection of different sites was made with reference to the gradient of urban activity and via physicochemical and biological evaluation of water quality and genotoxicity. The water quality index was classified as 'good' for P1 and P4, regular in P2 and 'poor' for P3. The micronuclei (MN) frequency obtained from blood analysis was in agreement with the water quality, such that the higher values of MN were detected in sites evaluated as poor. Water degradation conditions worsen according to the flow of the stream over the sites P1, P2 and P3, but for site P4, located after the Monte Carmelo Sewage Treatment Plant, improvements in the micronuclei frequency are detected. Our results showed high levels of potentially toxic metals (chromium, lead, aluminum and nickel) in specific stream sites (P2 and P3). We suggest that the micronuclei induction in G. brasiliensis could be due to the presence of these compounds.

n-TiO2 and CdCl2 co-exposure to titanium dioxide nanoparticles and cadmium: Genomic, DNA and chromosomal damage evaluation in the marine fish European sea bass (Dicentrarchus labrax)

Due to the large production and growing use of titanium dioxide nanoparticles (n-TiO2), their release in the marine environment and their potential interaction with existing toxic contaminants represent a growing concern for biota. Different end-points of genotoxicity were investigated in the European sea bass Dicentrarchus labrax exposed to n-TiO2 (1mgL(-1)) either alone and combined with CdCl2 (0.1mgL(-1)) for 7 days. DNA primary damage (comet assay), apoptotic cells (diffusion assay), occurrence of micronuclei and nuclear abnormalities (cytome assay) were assessed in peripheral erythrocytes and genomic stability (random amplified polymorphism DNA-PCR, RAPD assay) in muscle tissue. Results showed that genome template stability was reduced after CdCl2 and n-TiO2 exposure. Exposure to n-TiO2 alone was responsible for chromosomal alteration but ineffective in terms of DNA damage; while the opposite was observed in CdCl2 exposed specimens. Co-exposure apparently prevents the chromosomal damage and leads to a partial recovery of the genome template stability.