Ionotropic receptors mediate nitrogenous waste avoidance in Drosophila melanogaster

Subash Dhakal,Jiun Sang,Binod Aryal,Youngseok Lee

doi:10.1038/s42003-021-02799-3

Subash Dhakal, Jiun Sang + Show 2 more

Open Access

https://doi.org/10.1038/s42003-021-02799-3

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Journal: Communications Biology	Publication Date: Nov 12, 2021
Citations: 12	License type: open-access

Affiliation: Kookmin University

Abstract

Ammonia and its amine-containing derivatives are widely found in natural decomposition byproducts. Here, we conducted biased chemoreceptor screening to investigate the mechanisms by which different concentrations of ammonium salt, urea, and putrescine in rotten fruits affect feeding and oviposition behavior. We identified three ionotropic receptors, including the two broadly required IR25a and IR76b receptors, as well as the narrowly tuned IR51b receptor. These three IRs were fundamental in eliciting avoidance against nitrogenous waste products, which is mediated by bitter-sensing gustatory receptor neurons (GRNs). The aversion of nitrogenous wastes was evaluated by the cellular requirement by expressing Kir2.1 and behavioral recoveries of the mutants in bitter-sensing GRNs. Furthermore, by conducting electrophysiology assays, we confirmed that ammonia compounds are aversive in taste as they directly activated bitter-sensing GRNs. Therefore, our findings provide insights into the ecological roles of IRs as a means to detect and avoid toxic nitrogenous waste products in nature.

Highlights

Ammonia and its amine-containing derivatives are widely found in natural decomposition byproducts
Using a combined behavioral and electrophysiology approach, we discovered that flies perceive and avoid ammonia and its derivatives as bitter tastants via bitter-sensing gustatory receptor neurons (GRNs)
We found that nitrogenous wastes such as ammonium sulfate [(NH4)2SO4], ammonium chloride (NH4Cl), urea, and putrescine can activate S6 sensilla, but not L4, in a dosedependent manner (Fig. 1a)

Summary

Introduction

Ammonia and its amine-containing derivatives are widely found in natural decomposition byproducts. Female flies avoided laying their eggs on surfaces containing 50 mM of each chemical, and this response was mediated by bitter-sensing GRNs (Fig. 1e). Gr66a-GAL4/UAS-Kir2.1 female flies laid slightly more eggs on ammonia-containing food.

Results

Conclusion