RESUMO
The sensitivity of anuran to the effects of habitat destruction and contamination has led to a preoccupying global decline in their populations. Morphological biomarkers such as micronuclei and other erythrocyte nuclear abnormalities (ENAs), as well as the occurrence of hepatic melanin, can be used to evaluate the effects of habitat impacts. In the present study, these two parameters were combined for the in situ assessment of the effects of soybean cultivation on the grassfrog, Leptodactylus fuscus. Specimens were also collected from a protected area to provide a reference site (non-agricultural environment). The frequency of some of the nuclear abnormalities in the animals from the soybean plantation was much higher than that recorded at the reference site, in particular micronuclei, which were 3.6 times more frequent in the plantation, lobulated nuclei (3.4 times more frequent), and reniform nuclei, which were four times more common than at the reference site. The combined analysis of all the ENAs together also revealed a frequency approximately 1.4 times higher in the animals from the soybean plantation, in comparison with the protected area. Smaller areas of hepatic melanin were observed in the specimens from the soybean plantation. These results provide further evidence of the sensitivity of anurans to habitat impacts and indicate that animals found in soybean plantations are susceptible to systematic alterations of their cells.
Assuntos
Anuros , Melaninas , Animais , Brasil , Ecossistema , Eritrócitos , PradariaRESUMO
The Brazilian coast of the Rio de Janeiro State has bays of great economic, ecological and social importance. However, these ecosystems have been suffering intense anthropogenic influence, mainly due to the contamination by polycyclic aromatic hydrocarbons (PAHs) from urban-industrial activities. Moreover, PAHs are organic pollutants of high toxicity and carcinogenicity causing global concern to human and environmental health. This study evaluated on catfish (Genidens genidens) a set of key parameters (sex, morphometric traits, condition factor (K), PAH metabolites in gallbladder, frequency of micronucleus (MN) and erythrocytic nuclear abnormalities (ENA) in blood. In addition we also evaluated histopathological hepatic effects, Ethoxyresorufin-O-deethylase (EROD) activity and Benzo(a)pyrene diol epoxide (BPDE)-DNA adducts) in liver samples, in order to indicate the fish health status and environmental pollution levels of three main Bays (Guanabara, Sepetiba and Ilha Grande) of the Rio de Janeiro State, in the Southeast of Brazil. In general, the worst physical and metabolic conditions in catfishes were evidenced in Guanabara Bay, possibly indicating the highest level of contamination by PAHs. Contrary evidence was observed in Ilha Grande Bay, showing lower biological changes in G. genidens. However in Sepetiba Bay, the influence of PAHs contamination showed the highest hepatic lesions in catfishes, prevailing foci of cellular alterations, megalocytic hepatosis and hydropic vacuolations. The employability of a set of biomarkers on catfish was efficient for screening pollution for PAHs in tropical environments. This reinforces the need for effective actions of monitoring and conservation strategies of bays of the Rio de Janeiro State (Brazil), in order to ensure quality and health to both human and environment.
Assuntos
Peixes-Gato , Monitoramento Ambiental , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água , Animais , Baías , Brasil , EcossistemaRESUMO
In agricultural areas insecticides mixtures are frequently used, such as the combination of the pyrethroid lambda-cyhalothrin (LC) together with the neonicotinoid imidacloprid (IMI). Because of their extensive use, these insecticides can be found in freshwater bodies producing effects on aquatic organisms. However, there is a lack of studies concerning the combined effects of LC and IMI and their possible interactions. The objective of this study was to evaluate genotoxic and oxidative effects of LC and IMI, isolated and in binary mixture, on the neotropical freshwater teleost curimba (Prochilodus lineatus). Juveniles of P. lineatus were exposed to LC (0.15 µg L-1), IMI (100 µg L-1), LC + IMI or only to water (CTR) for 48, 96, 144 and 192 h. The occurrence of DNA damage (comet assay), was evaluated in erythrocytes, gills, liver and brain cells, the frequency of micronucleus (MN) and nuclear abnormalities (ENA) was measured in erythrocytes and protein carbonylation (PCC) and lipid peroxidation (LPO) were determined in gills, liver and brain. The results showed that LC and IMI, both alone and in combination, cause DNA damage in different tissues and ENA in the erythrocytes of P. lineatus. In addition, after shorter exposures a synergistic interaction between the insecticides was found in the blood and in the liver. LC showed to be the most toxic insecticide, even at much lower concentrations than IMI, causing DNA damage in all tissues analyzed, indicating that the effect of mixture is mainly due to the presence of the pyrethroid. The mixture LC + IMI also caused an increase in PCC and LPO in gills and liver after shorter exposures, indicating a probable synergistic interaction. The result of this interaction leads to an increased toxicity in shorter times, which can be harmful to fish in their natural environment.