scholarly journals Ionotropic receptors mediate nitrogenous waste avoidance in Drosophila melanogaster

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Subash Dhakal ◽  
Jiun Sang ◽  
Binod Aryal ◽  
Youngseok Lee

AbstractAmmonia 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.

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Kathrin Steck ◽  
Samuel J Walker ◽  
Pavel M Itskov ◽  
Célia Baltazar ◽  
José-Maria Moreira ◽  
...  

To optimize fitness, animals must dynamically match food choices to their current needs. For drosophilids, yeast fulfills most dietary protein and micronutrient requirements. While several yeast metabolites activate known gustatory receptor neurons (GRNs) in Drosophila melanogaster, the chemosensory channels mediating yeast feeding remain unknown. Here we identify a class of proboscis GRNs required for yeast intake. Within this class, taste peg GRNs are specifically required to sustain yeast feeding. Sensillar GRNs, however, mediate feeding initiation. Furthermore, the response of yeast GRNs, but not sweet GRNs, is enhanced following deprivation from amino acids, providing a potential basis for protein-specific appetite. Although nutritional and reproductive states synergistically increase yeast appetite, reproductive state acts independently of nutritional state, modulating processing downstream of GRNs. Together, these results suggest that different internal states act at distinct levels of a dedicated gustatory circuit to elicit nutrient-specific appetites towards a complex, ecologically relevant protein source.


Author(s):  
Jaekyun Choi ◽  
Lena van Giesen ◽  
Min Sung Choi ◽  
KyeongJin Kang ◽  
Simon G. Sprecher ◽  
...  

2017 ◽  
Author(s):  
Kathrin Steck ◽  
Samuel J. Walker ◽  
Pavel M. Itskov ◽  
Célia Baltazar ◽  
Carlos Ribeiro

ABSTRACTTo optimize fitness, animals must dynamically match food choices to their current needs. For drosophilids, yeast fulfils most dietary protein and micronutrient requirements. While several yeast metabolites activate known gustatory receptor neurons (GRNs) in Drosophila melanogaster, the chemosensory channels mediating yeast feeding remain unknown. Here we identify a class of proboscis GRNs required for yeast intake, and show that these GRNs act redundantly to mediate yeast feeding. While nutritional and reproductive states synergistically increase yeast appetite, we find a separation of these state signals at the level of GRN responses to yeast: amino acid but not mating state enhances yeast GRN gain. The sensitivity of sweet GRNs to sugar is not increased by protein deprivation, providing a potential basis for protein-specific appetite. The emerging picture is that different internal states act at distinct levels of a dedicated gustatory circuit to elicit nutrient-specific appetites towards a complex, ecologically relevant protein source.


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