Golden mussel (Limnoperna fortunei) as a bioindicator in aquatic environments contaminated with mercury: Cytotoxic and genotoxic aspects

This study evaluated the Limnoperna fortunei (golden mussel) as a bioindicator of cytotoxicity and genotoxicity in aquatic environments contaminated by heavy metals. Five groups of 50 subjects each were exposed to different concentration of mercuric chloride (HgCl₂) (0.001 mg/L, group I; 0.005 mg/L, group II; 0.01 mg/L, group II; 0.02 mg/L, group IV; and 0.1 mg/L, group V). The control group for both chronic and acute treatment did not receive HgCl₂. For chronic exposure, the respective groups were placed in aquaria with water contaminated with the above concentrations of HgCl₂. For acute exposure, the different concentrations of HgCl₂ were injected into the posterior adductor muscle of the individuals belonging to the aforementioned groups. The biological matrix used in the tests was the whole body muscle. Tests (cell viability assay, alkaline comet test; enumeration of micronuclei and necrotic cells, quantification of Hg content in tissues and water, and histopathological analysis of tissues), were carried out on the 7th, 15th, and 30th treatment days or 2 h after injection. Our results demonstrated that L. fortunei showed cell damage in both chronic and acute exposure groups. Significant DNA damage was observed at both the 15th (0.1 mg/L) and 30th (0.01-0.1 mg/L) days of chronic exposure. However, in acute treatment all concentrations induced DNA breaks. The presence of necrosis increased at all concentrations tested for both acute and chronic exposure. Tissue mercury retention on the 15th day was higher than on the 30th day of exposure, while in the same period, there was a decrease in the mercury content of aquarium water. Taking the data together, it is concluded that L. fortunei as a possible bioindicator of the quality of aquatic environments.

In vivo and in vitro genotoxicity studies of aqueous extract of Xanthium spinosum

The use of plants as a source of palliative or cure for pathological conditions is quite common worldwide. Xanthium spinosum (Asteraceae), popularly known in Brazil as 'espinho de carneiro', is an annual weed from South America, which has been used by empiric medicine to treat neoplasias. Owing to the extensive use of the above-mentioned plant and to the lack of reports about the real effects of its infusion, current study evaluated the genotoxic potential of its aqueous extract at concentrations 0.02 g L-1, 0.1 g L-1 and 0.2 g L-1 by fish micronucleus test and by comet human leukocytes assay. The micronucleus test featured at least 50 cells with micronuclei to every 2,000 cells scored, as a mutagenic parameter. The comet assay was used as a parameter for assessing the level of cell damage and the damage index. Since no significant changes in strain cells exposed to the aqueous extract in the comet and micronucleus assays were reported, it seems that no genotoxicity evidence is extant at the concentrations and in the assays performed.

Notas sobre a ocorrência de Tityus serrulatus Lutz & Mello, 1922 (Scorpiones, Buthidae) no oeste do Rio Grande do Sul, Brasil

O escorpião amarelo Tityus serrulatus é registrado pela primeira vez para oeste do Rio Grande do Sul. Foram coletados dois espécimes no município de Uruguaiana (29° 45' 23'' S e 57° 05' 37'' W) em junho de 2006. A ocorrência dos espécimes de T. serrulatus no Rio Grande Sul representa um aumento de 2.127 km em sua área de distribuição conhecida.