Characterization of cholinesterases in two freshwater invertebrates

KRISTOFF, G; VERRENGIA GUERRERO, N; SAN MARTÍN DE VIALE, L; PECHÉN D ANGELO, AM; COCHÓN, A

Pinamar, Buenos Aires

Congreso; Reunión Anual SAIB; 2005

SAIB

characterization of cholinesterases in two freshwater invertebrates. Kristoff, Gisela; Verrengia Guerrero, Noemí R.; San Martín de Viale, Leonor; Pechen de D’Angelo, Ana M. and Cochón Adriana. Depto Qca. Biológica, FCEyN, UBA. Ciudad Universitaria, Pab. II, 4to piso, (1428) Buenos Aires, Arg. Email:gkristoff@qb.fcen.uba.ar Cholinesterase (ChE) activity is widely used as biomarker for neurotoxic pesticides. However, prior to its use in a species is necessary to characterize the type of enzyme(s) present. The aim of this work was to characterize the ChE present in two freshwater invertebrates. Measurements of ChE activity from the whole body soft tissue of Biomphalaria glabrata and Lumbriculus variegatus were performed using two substrates: acetylthiocholine (AsCh) and butyrylthiocholine (BsCh) according to the method of Ellman. When using AsCh, B. glabrata presented almost all the activity in the 11,000 x g supernatant fraction (0.046 ± 0.006 µmol min-1 mg protein-1). L. variegatus presented values approx. 6 and 20 times higher of ChE activity than B. glabrata either in the supernatant or in the pellet, respectively. When using BsCh, significant values of enzyme activity were only detected in L. variegatus (72% of the total ChE). Iso-OMPA produced an inhibition of 72 % of ChE in L. variegatus, but only a slight decrease in B. glabrata. Increased concentrations of AsCh induced a progressive decrease in the ChE activity in both organisms (80% of inhibition at 34 mM of substrate). In L. variegatus inhibition by an excess of BsCh was also observed. ChE activity from L. variegatus was more sensitive to eserine inhibition than that from B. glabrata. According to our results both invertebrates present marked differences in ChE activity, type of enzymes and subcellular location. In addition L. variegatus was more sensitive to in vivo ChE inhibition induced by the organophosphate azinphos-methyl than B. glabrata.