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The Guaíba Basin is a source of drinking water for Porto Alegre (RS, Brazil). The water from this basin receives industrial, urban, and rural waste from many sources. The mussel species Limnoperna fortunei was chosen based on population data, distribution, and sensitivity. Previous tests with comet assay and micronuclei frequency in this freshwater mussel have shown to be successful in biomonitoring studies. The aim of this study was to evaluate the genotoxic contamination of the Guaíba Lake Hydrographic Region, through the determination of damage by the micronuclei and comet assays in L. fortunei (golden mussel). Nine sampling sites were evaluated in three different seasons: five sites in the mouths of the main rivers that flow into Guaíba lake; one site at the mouth of a stream; one major site of sewage discharge; two sites at Guaíba lake, near a sewage discharge; and the control site in a preservation area. DNA damage was detected by the single cell gel assay, as well as the frequency of micronuclei in hemocytes of mussels exposed under laboratory conditions for 7 days to water and sediment samples. Significant results were found in different seasons in almost all sampling sites (P<0.05, ANOVA Dunnet's test). Most of the positive results were found in samples affected mainly by urban effluents. It was possible to observe that there was a weak relation between mutagenic and genotoxic responses and mussels inorganic elements contents. Seasonal variation was observed at different sampling sites, but always indicating a huge contamination near urban sewage discharge. These results are consistent with previous studies, allowing us to infer that urban contamination is the biggest problem in this region. It is also possible to infer that L. fortunei is a good sentinel organism for the Guaíba Basin.

Exposure to coal and coal ashes can cause harmful effects in in vitro and in vivo systems, mainly by the induction of oxidative damage. The aim of this work was to assess cytotoxic and genotoxic effects using the V79 cell line treated with coal and coal fly ash particles derived from a coal power plant located in Santa Catarina, Brazil. Two coal samples (COAL11 and COAL16) and two coal fly ash samples (CFA11 and CFA16) were included in this study. COAL16 was co-firing with a mixture of fuel oil and diesel oil. The comet assay data showed that exposure of V79 cells to coal and coal fly ash particles induced primary DNA lesions. Application of lesion-specific endonucleases (FPG and ENDO III) demonstrated increased DNA effects indicating the presence of high amounts of oxidative DNA lesions. The cytokinesis-block micronucleus cytome assay analysis showed that exposure of V79 cells to high concentrations of coal and coal fly ash particles induced cytotoxic effects (apoptosis and necrosis) and chromosomal instability (nucleoplasmic bridges, nuclear buds, and micronucleus (MN) formation). These results may be associated with compounds contained in the surface of the particles as hazardous elements, ultrafine/nanoparticles, and polycyclic aromatic hydrocarbons (PAHs) which were detected in the samples. [ABSTRACT FROM AUTHOR]

Abstract: The development of methodologies for biomonitoring freshwater ecosystems is of particular relevance in view of the serious problem of aquatic environmental pollution. The mussel species Limnoperna fortunei (golden mussel) was chosen to be tested as a biomonitor organism based on its population data and distribution. L. fortunei individuals were exposed to UV radiation in vitro, and in vivo to pentachlorophenol (PCP) and copper sulphate (CuSO4), with the aim of standardizing comet assay and micronucleus test methodologies and evaluating the potential of this organism as a biomonitor. Haemolymph cells immobilized in agarose on slides exposed to UV radiation showed a dose–response relationship with maximum damage at 4.2J/m2. For the chemical tests, individuals were exposed for 2h for the comet assay and 24 and 48h for the micronucleus test. A dose–response relationship was observed for both chemicals. 3×10−5 M CuSO4 induced high genotoxicity, also producing some toxicity after 48h of exposure. PCP induced maximum damage in both assays at 150μg/L. Individuals exposed to PCP showed 100% repair 2h after the exposure period, as assessed by the comet assay. Exposure to an environmental sample over 7 days confirmed the mussel sensitivity to water contaminants, detected both by the comet assay and the micronucleus test. The results allow us to suggest the golden mussel as a potential biomonitor organism. [Copyright &y& Elsevier]

The widespread use of titanium dioxide nanoparticles (TiO 2 -NP) in consumer products is the cause of its appearance in wastewater and effluents, reaching the aquatic environment. The evaluation of the biological impact of TiO 2 -NP and the need to understand its ecotoxicological impact to the aquatic ecosystem are of major concern. Bivalve mollusks may represent a target group for nanoparticle toxicity. Limnoperna fortunei (golden mussel), a freshwater bivalve organism that has been employed in biomonitoring environmental conditions. Comet assay, micronucleus test and oxidative damage to lipids and proteins were performed after the golden mussel was exposed to TiO 2 -NP (1, 5, 10 and 50 μg mL −1 ). The results demonstrate that TiO 2 -NP can damage the DNA of haemocytes after 2 h of exposure and the genotoxic activity significantly increased after 4 h exposure to TiO 2 -NP, at all the TiO 2 -NP concentrations. TiO 2 -NP was ineffective in causing mutagenicity in the haemolymph cells of golden mussel. The increase in the lipid peroxidation levels and carbonyl proteins after the exposure to TiO 2 -NP indicates the induction of oxidative stress at 2 h exposure with similar results to all TiO 2 -NP concentrations, but these effects did not occur at 4 h exposure. These results demonstrated that, although TiO 2 -NP is not mutagenic to golden mussel, it does induce DNA damage and oxidative stress in these organisms. [ABSTRACT FROM AUTHOR]