Response of the antioxidant and detoxifying system in the anuran tadpole (Leptodactylus latrans) exposed to the organochlorine insecticide endosulfán

BACH N.; BAVIERA M.; MARINO D.; NATALE G.S.; RONCO A.E.; CARRIQUIRIBORDE P.

Bombhinas

Congreso; XI Congreso Brasilero de Ecotoxicologia; 2010

Sociedad Brasilera de Ecotoxicologia

The effect of the organochlorine insecticide endosulfán on the activity of EROD, GST, and CAT was assessed in tadpoles of the South-American anuran Leptodactylus latrans. Larvae (35-38 Gosner Stages) were exposed under laboratory conditions during 48h to 0, 10, 20 µg endosulfan L-1 and 1.5 µM β-naphthoflavone (EROD positive control) using a semi-static system (media replacement every 24h). Treatments were run by triplicate using 15 individuals per replica. DMSO was the solvent and the same concentration was used in all groups. Water samples were collected every 24h after each replacement for chemical analysis (CG-ECD). Livers of each organism were sampled at 8, 24, and 48h, immediately frozen in dry ice, and kept at -80 °C for tissue homogenization and biochemical analysis. EROD (ethoxyresorufin-O-deethylase) activity was assessed following the method of Quabius et. al 2002. GST (glutathione-S-transferase) was conducted using the method of Stephensen et. al 2002. CAT (catalase) was performed using the method of Vlahogianni et. 2007. Concentration of endosulfán in the water decreased 97% during the 24hs between replacement, and isomer ratio alfa/beta shift from 1.37 to 0.60 indicating a selective uptake by the organisms. Significant mortalities respect to controls were registered only at the highest tested concentration, with values of 58% and 72% after 24 and 48h, respectively. Metamorphic rate was not significantly affected among treatments. The EROD activity (mean ± SD) in control group was 178.4 ± 15.4 pmol min-1 mg prot-1. Though, EROD activity in positive controls showed a 2.2-fold induction respect to the non-exposed group, no significant effects were observed with endosulfan concentration or exposure time (p