Cofactor-enabled functional expression of fruit fly, honeybee, and bumblebee nicotinic receptors reveals picomolar neonicotinoid actions
Makoto Ihara, Shogo Furutani, Sho Shigetou, Shota Shimada, Kunihiro Niki, Yuma Komori, Masaki Kamiya, Wataru Koizumi, Leo Magara, Mai Hikida, Akira Noguchi, Daiki Okuhara, Yuto Yoshinari, Shu Kondo, Hiromu Tanimoto, Ryusuke Niwa, David B. Sattelle, Kazuhiko Matsuda
Abstract
Significance Neonicotinoids acting on insect nicotinic acetylcholine receptors (nAChRs) are deployed for crop protection, but growing evidence for adverse effects on insect pollinators has led to restricted use of some neonicotinoids in the EU. It is therefore vital to understand the target site actions of neonicotinoids in pollinators, but to date the difficulties of heterologous expression of insect nAChRs have hampered progress. We have found that a thioredoxin (TMX3) enables robust functional expression of honeybee, bumblebee, and fruit fly nAChRs in Xenopus laevis oocytes. With this advance, we show that expressed bee nAChRs are more neonicotinoid-sensitive than those of fruit fly, and clothianidin can modulate both honeybee and bumblebee nAChRs at a concentration below that commonly observed in agricultural fields.