No abstract

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) and the occurrence of hepatic melanin can be used to evaluate the effects of habitat impacts. In the present study, these two procedures 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 control (non-agricultural environment).The frequency of some nuclear abnormalities in the animals from the soybean plantation was much higher than the control, speci cally, micronuclei were 3.6 times more frequent, while lobulated nuclei were 3.4 times more frequent, and reniform nuclei, four times more common. The combined analysis of all the ENAs 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 the cells.

Anurans are vulnerable to damage caused by the modification of habitats, as well as their contamination by xenobiotic substances. However, little is known of the plasticity of biomarkers once the exposure to these conditions has ceased. The present study evaluated whether Physalaemus nattereri is subject to erythrocytic nuclear alterations and modifications of the hepatic melanin in agricultural environments, and whether these impacts are reduced when the animal is isolated from this exposure. Twenty adult P. nattereri were collected from soybean (n = 10) and sugarcane (n = 10) plantations for the analysis of erythrocytic nuclear abnormalities and the hepatic melanin. An additional 20 animals were taken from the same environments and were maintained in contaminant-free terrariums under controlled conditions in the laboratory for 30 days prior to the application of the same analytical procedures. The results indicated that the animals from agricultural environments had higher levels of mutagenic damage in comparison with the individuals that were isolated from exposure to contaminants in the laboratory. The analysis of the hepatic melanin revealed a smaller area occupied by the melanomacrophages in the animals exposed to both types of plantation. The evidence indicates that the biomarkers are highly plastic, and reflect the environmental conditions, given that the genotoxic alterations decrease once the exposure is interrupted. The reduced area of hepatic melanin in the animals exposed to agricultural environments may reflect the incapacitation of the melanomacrophages and the loss of their detoxification potential due to the continuous exposure of the animal to agricultural pollutants.

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) and the occurrence of hepatic melanin can be used to evaluate the effects of habitat impacts. In the present study, these two procedures 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 control (non-agricultural environment). The frequency of some nuclear abnormalities in the animals from the soybean plantation was much higher than the control, specifically, micronuclei were 3.6 times more frequent, while lobulated nuclei were 3.4 times more frequent, and reniform nuclei, four times more common. The combined analysis of all the ENAs 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 the cells.