Molecular and enzymatic responses to organophosphates in Bufo arenarum embryos

SOTOMAYOR VERONICA; VENTURINO ANDRÉS; FERRARI ANA; PECHÉN DE D'ANGELO ANA M

Pinamar, Pcia. Buenos Aires, Argentina

Congreso; X Congreso de la Panamerican Association for Biochemistry and Molecular Biology (PABMB), XLI Reunión Annual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB), XX Reunión Annual de la Sociedad Argentina de Neuroquímica (SAN); 2005

Panamerican Association for Biochemistry and Molecular Biology (PABMB)

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 here the effects of a low exposure to the OP chlorpyrifos (Cpf) (2 mg/L, 1/7 LC50) and Mtn (20 mg/L, 1/2 LC50) in early embryogenesis. Antioxidant enzyme activities were measured kinetically, AP-1 TRE-binding was determined by EMSA, and nuclear protein phosphorylation was performed with 32P-ATP and analyzed by SDS-PAGE and autoradiography. Cpf tended to lower catalase and GSH-S-transferase and increase GSH-reductase activities, while Mtn induced the 3 enzymes (25, 100 and 50% respectively). In turn, both OP clearly reduced AP-1 binding, and increased protein phosphorylation (29KDa; 43 KDa). Western blot analyses of c-Jun and phosphorylated c-Jun gave yet no conclusive results. Enzyme responses are more evident in sublethal Mtn than in low Cpf exposures. However, molecular events regarding AP-1 and phosphorylation, point out that Cpf is nevertheless affecting early development of B. arenarum. AP-1 downregulation may be reflecting other mechanisms shared by c-Jun, such as Antioxidant Response Element binding.