Biochemical biomarkers of agrochemical exposure in tadpoles used for water monitoring

DUBOSK, L; SOLEÑO J; MONTAGNA M; ROSENBAUM E; VENTURINO A

Rosario

Congreso; 42ª Reunión Anual de la SAIB; 2006

SAIB

Biomarkers are appropriate tools for pesticide environmental impact evaluation. In Bufo arenarum larvae, glutathione (GSH)-S-transferase (GST), and carboxylesterase (CE) activities were proposed as biomarkers of pesticide effect. We tested biomarker responses in caged tadpoles in water channels during fruit production season, and compared them with those elicited by a transient exposure to azinphosmethyl (AM) (0.02-2 mg/ml; 4 h), the main pesticide applied in the region. Larvae showed a significant decrease of GSH (58-45%) at 1-2 week-exposure in water channels, correlated with a significant increase in GST activity (51-20%). CE was significantly decreased (26-37%), while the activity of acetylcholinesterase (AChE) was increased (24%) in the first week but then inhibited (34%) in the second week. These responses were emulated to a varying degree by laboratory assays: AChE and GST were induced, CE was inhibited and GSH was decreased immediately after 4 h exposures to AM; only GST and GSH showed changes during the recovery at 2 d. Biomarker responses are compatible with pesticide applications registered during the experiments. GST is known to be induced by oxidative stress through GSH depletion. CE acts as a buffer sequestering pesticide to avoid AChE inhibition until it is overloaded, and AChE induction at mild exposures may be related to the recently described resilient isoenzyme.