Differential expression of acetylcholinesterase 1 in response to various stress factors in honey bee workers

Abstract

The honey bee acetylcholinesterase 1 (AmAChE1) has been suggested to be related to stress response as judged from its elevated expression level under brood rearing-suppressed conditions. To further investigate the involvement of AmAChE1 expression in the stress response and its physiological functions, we analyzed altered expression profiles of AmAChE1 induced by diverse stress factors. In addition, transcription profiles of several heat shock protein (Hsp) genes ( hsps ) and the vitellogenin (Vg) gene ( vg ) known as general stress markers were investigated as positive references. Among the tested stress conditions, AmAChE1 expression was induced under the brood rearing-suppressed, crowding and heat shock conditions. The hsps , particularly hsp70 and hsp90 , responded to seven of nine stress conditions tested, confirming that hsp expression profiles can serve as a general stress marker. Taken together, AmAChE1 expression is not suitable for using as a stress marker due to its limited response. Nevertheless, AmAChE1 expression appears to be connected, at least in part, to heat shock response and other pathways. Considering that AmAChE1 likely regulates the ACh titer particularly in non-neuronal tissues, thereby modulating the signal cascades mediated by mAChR, the AmAChE1 expression profile under different conditions likely provides important information on its physiological roles in honey bees.

Response mechanisms to heat stress in bees

“…Bees not only respond to heat stress through behavioral changes, they also enhance their heat resistance by gene expression regulation. Under heat stress, bees induce the expression of many key genes and proteins, including Hsp, NF-Y, acetylcholinesterase 1 (AchE1), and zinc finger protein (ZFP) (Figure 1b) (Kim et al 2019;Li et al 2020a, b;Ma et al 2019;Zhang et al 2014). In addition, heat stress can cause the production of reactive oxygen species (ROS).…”

“…Bees cannot bear this degree of heat stress and will die oxidative damage and enhancing antioxidant ability (Figure 2) (Li et al 2020b). In addition, a recent study reported that the expression of honeybee AChE1 is significantly induced by heat stress, and this induction degree is more apparent in the abdomen than in the head (Kim et al 2019). A recent transcriptome study showed that the mRNA levels of ZFP (such as ZFP271 , ZFP37 , ZFP239 , ZFP776 , and ZFP93 ) and serine/ threonine protein kinase (STK ) (such as STK-6 ) are regulated by high temperatures, indicating that they may function in the response of bees to heat stress (Ma et al 2019).…”

“…In particular, the discovery of genes that respond to both heat stress and other stresses could indicate that bees may be able to deal with simultaneous environmental stresses. Second, because bees have different tolerances to heat stress at different developmental stages (Alqarni et al 2019;Jones et al 2005;Kim et al 2019), further experiments can explore genes and signal pathways involved in heat resistance at various developmental stages of bees, which may suggest stage-specific-targeted control strategies. Third, although the effect of heat stress on bee behavior is relatively clear (Bonoan et al 2014;Johnson 2002;Southwick and Heldmaier, 1987), the molecular regulatory networks and neurological components in bees underlying their responses to heat stress still require more study.…”

Estimation of the Acetylcholinesterase activity of honey bees in Nepal

“…Johnson et al 2013; Straub et al 2019). Identification of suitable biomarkers for the prior detection of stress in honey bee colonies, therefore, becomes crucial for proactive management (Kim et al 2019). Various biomolecules including glutathione-S-transferase, acetylcholinesterase (AChE), metallothioneins, alkaline phosphatase, nicotinic acetylcholine receptors (nAChRs), cytochrome P450 oxidase, vitellogenin and α-tocopherol are used to assess the effects of diverse stressors in honey bees (Badiou-Bénéteau et al 2013; Christen & Fent 2017; Gauthier et al 2018).…”

“…Various biomolecules including glutathione-S-transferase, acetylcholinesterase (AChE), metallothioneins, alkaline phosphatase, nicotinic acetylcholine receptors (nAChRs), cytochrome P450 oxidase, vitellogenin and α-tocopherol are used to assess the effects of diverse stressors in honey bees (Badiou-Bénéteau et al 2013;Christen & Fent 2017;Gauthier et al 2018). Enzymatic biomarker, AChE is targeted as a promising candidate, because of its vulnerability to express differentially in relation to the pesticide exposure (Boily et al 2013; but see Kim et al 2019), seasonal condition (Kim et al 2017), landscape (Badiou-Bénéteau et al 2013) and nutrition status (Kim et al 2017(Kim et al , 2019. AChE rapidly hydrolyses ACh at the cholinergic synapses, thus allowing precise control and modulation of the neural transmission (Badiou et al 2008).…”