Ecotoxicological Biomarkers in Multiple Tissues of the Neotenic Ambystoma spp. for a Non-lethal Monitoring of Contaminant Exposure in Wildlife and Captive Populations

Amphibians are the most threatened vertebrate group with a third of currently known species endangered with extinction, as a result of climate change, habitat loss, disease-introduced exotic species, and pollution. Because of their vulnerability, they have often been used as environmental quality indicators, as well as laboratory models for toxicological research. Given the sensitivity of amphibians to changes in their surrounding environment, including pollution, it was deemed important to define a non-lethal technique based on the evaluation of a set of biomarkers in different tissues of neotenic individuals of Ambystoma velasci. The levels of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carboxylesterase (CaE), alkaline and acid phosphatases (ALP, ACP), glutathione s-transferase (GST), 7-ethoxyresorufin-O-deethylase (EROD), and superoxide dismutase (SOD) activities, as well as the oxygen radical absorption capacity (ORAC) were measured in tail, gills, liver, plasma, and brain samples. Significant tissue-specific differences were observed for all biomarkers with the exception of ACP. The highest values of specific activity for most biomarkers were detected in the liver. However, the levels measured in gills were very close to those observed in the liver and showed fewer variations than other tissues. These findings suggest that the sampling of gills could be used to evaluate pollution biomarkers in salamanders without apparent harm, as this tissue quickly regenerates.