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(77-20) Field exposure to organophosphorus insecticides assessed by serum butyrylcholinesterase inhibition in lizards. Sanchez Hernandez, Juan*,1, Sanchez Moreno, Beatriz1, Henriquez Perez, Alicia1, 1 Departamento de Ciencias Ambientales, Toledo, Toledo ABSTRACT- Field and laboratory experiments were conducted to validate the potential use of serum butyrylcholinesterase (BChE) activity in lizards (Gallotia galloti) as a nondestructive biomarker of organophosphorus (OP) exposure. In vitro experiments were performed to characterize BChE activity and to investigate chemical reactivation of phosphorylated enzyme in the presence of pralidoxime (2-PAM). Field experiments consisted of two sampling campaigns carried out in 3 agricultural areas and 2 sites - considered as non-polluted - of the Tenerife Island (Spain). Blood samples (n = 204, 1st sampling; n = 96, 2nd sampling) were collected from lizards, maintaned on ice during transport and stored at -80°C. BChE and acetylcholinesterase (AChE) activities were identified in lizard serum. BChE activity represented a 83 % of total cholinesterase activity and butyrylthiocholine appeared to be the most suitable substrate for assaying BChE activity. The optimum range of pH and substrate concentrations for measuring enzyme activity were 7.5 - 8.0 and 2 - 5 mM, respectively. Reactivation of OP-inhibited BChE activity was highly dependent on OP type, concentration of 2-PAM and inhibition degree of BChE. Satisfactory reactivation of phosphorylated BChE occurred over 60-min incubation period in the presence of 10-4 M of 2-PAM. Significant increase (6 - 90 %) of BChE activity after 2-PAM incubation was observed in the 20% of samples collected at the agricultural areas. Serum BChE activity of G. galloti and the ability of 2-PAM to reactivate the phosphorylated enzyme resulted to be a suitable nondestructive methodology to assess field OP exposure in this vertebrate species. Key words: Butyrylcholinesterase, Nondestructive biomarker, Lizards, 2-PAM |
