Esterase activity and detection of carboxylesterase and phosphotriesterase in female desert locust Schistocerca gregaria (Forskal) in relation to tissues and ages

Abstract

General esterases activity in the different body tissues of adult females of 2-day and 13-day-old Schistocerca gregaria (Forskal) were measured spectrophotometricaly and carboxylesterase and phosphotriesterase were characterized by electrophoresis method. Esterase activities were studied in the tissues of brain, fore-, mid-, hindgut and ovary of the two ages in the presence of α-naphthyl acetate as a substrate and ethylenediamine tetraacetic acid (EDTA) and profenofos as inhibitors. Spectrophotometric analysis indicated that the esterase activity in adult S. gregaria tissues was significantly higher in the tissues of mid-, foregut, ovary and brain of 2day-old females than those of 13-day-old, respectively. Meanwhile, the activity was greater in the hindgut tissue of 13-day-old females than in 2-day-old ones. Nondenaturing polyacrylamide gel electrophoresis revealed differences in isozyme composition. Three to ten esterase bands were detected in the different body tissues of the two ages of adult females. These bands were characterized as phosphotriesterase and carboxylesterase by using the two inhibitors. Bands Est-1, Est-2, Est-3 and Est-6 were found to be carboxylesterase in the different tissues, while band Est-4 was only detected to be phosphotriesterase.