Acetylcholinesterase from <i>Apis mellifera</i> head. Evidence for amphiphilic and hydrophilic forms characterized by Triton X-114 phase separation

Belzunces, Luc; Toutant, Jean‐Pierre; Bounias, M.

doi:10.1042/bj2550463

Cited by 46 publications

(21 citation statements)

References 39 publications

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“…The differences between AChE inhibitor potency in the gut and brain tissue extracts are more difficult to explain, and it is unclear what physiological relevance this finding may have. It may suggest that levels of the different AChE enzymes differ between tissues; previous studies have identifies at least two different AChE proteins in the honeybee (Belzunces et al, 1988; Badiou et al, 2007). …”

Section: Discussionmentioning

confidence: 97%

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Exposure to Acetylcholinesterase Inhibitors Alters the Physiology and Motor Function of Honeybees

et al. 2013

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Cholinergic signaling is fundamental to neuromuscular function in most organisms. Sub-lethal doses of neurotoxic pesticides that target cholinergic signaling can alter the behavior of insects in subtle ways; their influence on non-target organisms may not be readily apparent in simple mortality studies. Beneficial arthropods such as honeybees perform sophisticated behavioral sequences during foraging that, if influenced by pesticides, could impair foraging success and reduce colony health. Here, we investigate the behavioral effects on honeybees of exposure to a selection of pesticides that target cholinergic signaling by inhibiting acetylcholinesterase (AChE). To examine how continued exposure to AChE inhibitors affected motor function, we fed adult foraging worker honeybees sub-lethal concentrations of these compounds in sucrose solution for 24 h. Using an assay for locomotion in bees, we scored walking, stopped, grooming, and upside down behavior continuously for 15 min. At a 10 nM concentration, all the AChE inhibitors caused similar effects on behavior, notably increased grooming activity and changes in the frequency of bouts of behavior such as head grooming. Coumaphos caused dose-dependent effects on locomotion as well as grooming behavior, and a 1 μM concentration of coumaphos induced symptoms of malaise such as abdomen grooming and defecation. Biochemical assays confirmed that the four compounds we assayed (coumaphos, aldicarb, chlorpyrifos, and donepezil) or their metabolites acted as AChE inhibitors in bees. Furthermore, we show that transcript expression levels of two honeybee AChE inhibitors were selectively upregulated in the brain and in gut tissues in response to AChE inhibitor exposure. The results of our study imply that the effects of pesticides that rely on this mode of action have subtle yet profound effects on physiological effects on behavior that could lead to reduced survival.

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Section: Discussionmentioning

confidence: 97%

“…Honeybees have two active forms of the AChE enzyme (Belzunces et al, 1988; Badiou et al, 2007); one form, AChE m1 , is expressed at a much higher level in the bee’s head than the other (AChE m2 ; Belzunces et al, 1988). It is possible that chronic exposure to an AChE inhibitor could affect expression of these two enzymes.…”

Section: Introductionmentioning

confidence: 99%

Exposure to Acetylcholinesterase Inhibitors Alters the Physiology and Motor Function of Honeybees

et al. 2013

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“…In the calyces, the PNs make synaptic contacts with mushroom body intrinsic Kenyon cells. Acetylcholinesterase histochemistry, immunocytochemical staining for nAChRs, a-bungarotoxin (BGT) binding sites indicate cholinergic transmission in the AL and the existence of a cholinergic pathway via some olfactory projections neurones into the mushroom bodies (Belzunces et al 1988;Kreissl and Bicker 1989;Scheidler et al 1990). As the LINs and PNs are targets of ORNs and Kenyon cells, they are possibly to express nAChRs (for review see Bicker 1999).…”

Section: Introductionmentioning

confidence: 99%

Study of nicotinic acetylcholine receptors on cultured antennal lobe neurones from adult honeybee brains

et al. 2007

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In insects, acetylcholine (ACh) is the main neurotransmitter, and nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission. In the honeybee, nAChRs are expressed in diverse structures including the primary olfactory centres of the brain, the antennal lobes (AL) and the mushroom bodies. Whole-cell, voltage-clamp recordings were used to characterize the nAChRs present on cultured AL cells from adult honeybee, Apis mellifera. In 90% of the cells, applications of ACh induced fast inward currents that desensitized slowly. The classical nicotinic agonists nicotine and imidacloprid elicited respectively 45 and 43% of the maximum ACh-induced currents. The ACh-elicited currents were blocked by nicotinic antagonists methyllycaconitine, dihydroxy-beta-erythroidine and alpha-bungarotoxin. The nAChRs on adult AL cells are cation permeable channels. Our data indicate the existence of functional nAChRs on adult AL cells that differ from nAChRs on pupal Kenyon cells from mushroom bodies by their pharmacological profile and ionic permeability, suggesting that these receptors could be implicated in different functions.

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“…In a previous study, two specific aggregates of membrane AChE (13S and 11S) from honeybee head were identified in sucrose gradient sedimentation (Belzunces et al, 1988b). We propose to thoroughly investigate the nature of these specific membrane AChE aggregates.…”

Section: Introductionmentioning

confidence: 88%

Existence of two membrane-bound acetylcholinesterases in the honey bee head

Badiou¹,

Brunet²,

Belzunces³

2007

Arch. Insect Biochem. Physiol.

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Two acetylcholinesterase (EC 3.1.1.7) membrane forms AChE(m1) and AChE(m2), have been characterised in the honey bee head. They can be differentiated by their ionic properties: AChE(m1) is eluted at 220 mM NaCl whereas AChE(m2) is eluted at 350 mM NaCl in anion exchange chromatography. They also present different thermal stabilities. Previous processing such as sedimentation, phase separation, and extraction procedures do not affect the presence of the two forms. Unlike AChE(m1), AChE(m2) presents reversible chromatographic elution properties, with a shift between 350 to 220 mM NaCl, depending on detergent conditions. Purification by affinity chromatography does not abolish the shift of the AChE(m2) elution. The similar chromatographic behaviour of soluble AChE strongly suggests that the occurrence of the two membrane forms is not due to the membrane anchor. The two forms have similar sensitivities to eserine and BW284C51. They exhibit similar electrophoretic mobilities and present molecular masses of 66 kDa in SDS-PAGE and a sensitivity to phosphatidylinositol-specific phospholipase C in non-denaturing conditions, thus revealing the presence of a glycosyl-phosphatidylinositol anchor. We assume that bee AChE occurs in two distinct conformational states whose AChE(m2) apparent state is reversibly modulated by the Triton X-100 detergent into AChE(m1).

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Acetylcholinesterase from Apis mellifera head. Evidence for amphiphilic and hydrophilic forms characterized by Triton X-114 phase separation

Cited by 46 publications

References 39 publications

Exposure to Acetylcholinesterase Inhibitors Alters the Physiology and Motor Function of Honeybees

Exposure to Acetylcholinesterase Inhibitors Alters the Physiology and Motor Function of Honeybees

Study of nicotinic acetylcholine receptors on cultured antennal lobe neurones from adult honeybee brains

Existence of two membrane-bound acetylcholinesterases in the honey bee head

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