Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
Molecular biology of tick acetylcholinesterases
Ticks vector many pathogens with major health and economic impacts and have developed resistance to most acaricides used for tick control. Organophosphate (OP) acaricides target acetylcholinesterase (AChE) critical to tick central nervous system function. Mutations producing tick AChEs resistant to OPs were characterized; but tick OP-resistance is not fully elucidated, due to remarkable complexity of tick cholinergic systems. Three paralogous tick AChEs exhibiting differences in primary structure and biochemical kinetics are encoded by amplified genes with developmentally regulated expression. Gene silencing data suggest tick AChEs are functional complements in vivo, and transcriptomic and genomic data suggest existence of additional tick AChEs. Cholinergic systems are crucial in neural transmission and are also regulators of vertebrate immune function. Ticks exhibit prolonged intimate host contact, suggesting adaptive functions for tick cholinergic system complexity. AChE was recently reported in tick saliva and a role in manipulation of host immune responses was hypothesized. Physiological roles and genetic control of multiple tick AChEs requires further elucidation and may provide unique opportunities to understand and manipulate cholinergic involvement in biological systems.