IQUIBICEN   23947
INSTITUTO DE QUIMICA BIOLOGICA DE LA FACULTAD DE CIENCIAS EXACTAS Y NATURALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effects of subchronic exposure to azinphos-methyl on B-esterases activitity, reproduction and offspring survival in a freshwater gastropod
Autor/es:
COSSI, PAULA FANNY; BOBURG, BEVERLY; PÉREZ, ANALÍA FERNANDA; KRISTOFF, GISELA
Reunión:
Congreso; SETAC Latin America 11th Biennial Meeting; 2015
Resumen:
Organophosphate (OP) insecticides are commonly used in our country and around the world for pest control on food crops. The mechanism of action of OP insecticides consists in the inhibition of acetylcholinesterase enzyme. In the present work different biochemical and reproductive effects were studied in Biomphalaria straminea, a freshwater gastropod naturally distributed in Argentina, after a subchronic exposure (14 days) to environmental concentrations of the OP azinphos-methyl (AZM).Bioassays were performed in 250 mL glass vessels housing 3 snails each. Six vessels were used for each treatment: water control, solvent control (acetone), 20 and 200 µg/L of AZM. Organisms were fed every 7 days and insecticide solutions were renewed every 4 days. After 14 days, soft tissues of the 3 snails from each recipient were homogenized together and centrifuged at 11,000 xg. In the supernatant fraction, cholinesterase (ChE) activity was measured using acetylthiocholine and carboxylesterase (CE) activity with p-nitrophenyl acetate and p-nitrophenyl butyrate as substrates. Along the 14 days each egg mass was transferred to individual containers, where it received the same treatment as adults until hatching. Following parameters were registered: number of egg masses, number of eggs per egg mass, number of eggs with embryo per egg mass, time to hatching and number of hatchings per egg mass. When hatching, juveniles were transferred to clean water and survival was recorded over a month.Results showed a strong inhibition in the activity of CEs with both substrates. The activity of the enzyme decreased around 60% with 200 µg/L of AZM respect to control. By contrast, ChE activity, in spite of being the primary target of OPs, did not show inhibition after 14 days of exposure. Reproductive parameters analyzed were not statistically different from control. Nevertheless, many egg masses coming from 20 and 200 µg/L AZM treatments showed arrested embryonic development at early stages and some juveniles coming from the highest AZM concentration hatched with different morphology than controls. Offspring survival from 200 µg/L AZM treatment was 16% lower than control.CEs can be used as a sensible biomarker after subchronic exposure to AZM in B. straminea. Offspring survival could be included in further studies as possible effect biomarkers. The decrease in survival could lead to a decline in the number of organisms of a species which may threaten the integrity of natural ecosystems.