Changes in acetylcholinesterase during pupal development of Apis mellifera queen

Abstract

Total, membrane, and soluble acetylcholinesterase (AchE, EC 3.1.1.7) activities increase during the pupal development of Apis mellifera queen to reach maximum values at emergence. Membrane and soluble AchE are inhibited by 10-5 M eserine or BW284C51 except at Pr, Pdm, and Pdd stages in which soluble AchE presents eserine-sensitive and eserine-resistant fractions. At all pupal stages, AchE occurs in a major amphiphilic membrane form that represents about 98% of total AchE activity and whose sedimentation coefficient is about 5.7S, and in a minor hydrophilic form that represents about 2% of total AchE activity and whose sedimentation coefficient is about 7S. At all pupal stages, phosphatidylinositol-specific phospholipase C (PI-PLC) and glycosyl phosphatidylinositol-specific phospholipase D (GPI-PLD) convert the membrane form into soluble counterparts which electrophoretic mobilities differ from that of the soluble form. AchE exhibits a butyrylcholinesterase (BuChE) activity that represents about 14% of AchE activity. During pupal development, the BuChE/AChE ratio of the membrane fraction is relatively stable, whereas the BuChE/AChE ratio of the soluble fraction is subjected to significant variations. At early pupal stages (Pw–Pd), membrane AchE displayed a high Km value, higher than 40 μM, that decreases to an intermediary value of about 30 μM at Pdl and Pdm stages, to reach finally about 20 μM at Pdd and emergence stages. Arch. Insect Biochem. Physiol. 36:69–84, 1997. © 1997 Wiley-Liss, Inc.