Molecular stress responses in Bufo arenarum embryos to organophosphorus pesticides

SOTOMAYOR V; VENTURINO A; FERRARI A; PECHEN DE D´ANGELO, A.M

Pinamar, Buenos Aires, Argentina

Congreso; X Congress of the Panamerican Association of Biochemistry and Molecular Biology (PABMB), XLI Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB) and XX Annual Meeting of the Argentine Society for Neurochemistry (SAN); 2005

PABMB, SAIB y SAN

There is concern in the Alto Valle de Río Negro y Neuquén about pesticide undesirable effects in biota as a result of their high level of use in fruit production. Amphibians are particularly sensitive to environmental pollutants during embryonic development. We previously showed the adverse effects of sublethal doses of malathion (Mtn) and other organophosphates (OP) causing oxidative stress in  B.arenarum embryo. We analyze and compare here the effects of a low exposure to the OP chlorpyrifos (Cpf) (2 mg/L, 1/7 LC50) vs. Mtn (20 mg/L, ½ LC50), on antioxidant enzymes and signaling events in early embryogenesis. Catalase, GSH reductase (GR) and GSH-S-transferase (GST) activities were measured kinetically, AP-1 binding was determined by EMSA, protein phosphorylation was performed with 32P-ATP and analyzed by SDS-PAGE and autoradiography, and Western blots used to study c-Jun. At 48 h of development Cpf tended to lower catalase and GST activities and increase GR; as previously stated, Mtn clearly induced GST (2X), catalase (25%) and GR (50%). In turn, AP-1 binding was clearly reduced by both OP. Altered phosphorylation patterns of nuclear proteins were obtained, increasing at about 33? and 48? kD bands. Western blot analyses of c-Jun and phosphorylated c-Jun yet gave no conclusive results. Oxidative responses are more evident in sublethal Mtn than in low Cpf exposures. However, molecular events at AP-1 and phosphorylation point out that Cpf is nevertheless affecting early development of B. arenarum. While perhaps not directly related to oxidative stress, AP-1 binding downregulation may be reflecting other mechanisms shared by c-Jun, such as Antioxidant Response Element.