EXPRESSION AND EFFECTS OF MUTANT Bombyx mori ACETYLCHOLINESTRASE1 IN BmN CELLS

The main mechanism of toxicity of organophosphate (OP) and carbamate (CB) insecticides is their irreversible binding and inhibition of acetylcholinestrase (AChE), encoded by ace 1 (acetylcholinestrase gene 1), leading to eventual death of insects. Mutations in AChE may significantly reduce insects susceptibility to these pesticides. Bombyx mori is an important beneficial insect, and no OP‐ or CB‐resistant strains have been generated. In this study, wild‐type ace 1 ( wace 1) and mutant ace 1 ( mace 1) were introduced into Bm N cells, confirmed by screening and identification. The expression of wace 1 and mace 1 in the cells was confirmed by Western blot and their expression levels were about 21‐fold higher than the endogenous ace 1 level. The activities of AChE in wace 1 and mace 1 transgenic cells were 10.6 and 20.2% higher compared to control cells, respectively. mace 1 transgenic cells had higher remaining activity than wace 1 transgenic cells under the treatment of physostigmine (a reversible cholinesterase inhibitor) and phoxim (an OP acaricide). The results showed that ace 1 transgene can significantly improve ace 1 expression, and ace 1 mutation at a specific site can reduce the sensitivity to AChE inhibitors. Our study provides a new direction for the exploration of the relationship between AChE mutations and drug resistance.