A specific receptor site for glycerol, a new sweet tastant for Drosophila: Structure-taste relationship of glycerol in the labellar sugar receptor cell

Takaya Koseki, Masayuki Koganezawa, Akira Furuyama, Kunio Isono, Ichiro Shimada

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

Glycerol, a linear triol, is a sweet tastant for mammals but it has not previously been recognized to stimulate the sense of taste in insects. Here we show by electrophysiological experimentation that it effectively stimulates the labellar sugar receptor cell of Drosophila. We also show that in accord with the electrophysiological observations, the behavioral feeding response to glycerol is dose dependent. 3-Amino-1,2-propanediol inhibited the response of the sugar receptor cell to glycerol, specifically and competitively, while it had almost no effect on responses to sucrose, D-glucose, D-fructose and trehalose. In the null Drosophila mutant for the trehalose receptor (ΔEP19), the response to glycerol showed no change, in sharp contrast with a characteristic drastic decrease in the response to trehalose. The glycerol concentration-response curves for I-type and L-type labellar hairs were statistically indistinguishable, while those for sucrose, D-glucose, D-fructose and trehalose were clearly different. These all indicate the presence of a specific receptor site for glycerol. The glycerol site was characterized by comparing the effectiveness of various derivatives of glycerol. Based on this structure-taste relationship of glycerol, a model is proposed for the glycerol site including three subsites and two steric barriers, which cannot accommodate carbon-ring containing sugars such as D-glucose.

Original languageEnglish
Pages (from-to)703-711
Number of pages9
JournalChemical Senses
Volume29
Issue number8
DOIs
Publication statusPublished - 2004

Keywords

  • Chemoreception
  • Electrophysiology
  • Fly
  • Inhibitor
  • Mutant
  • Receptor model

ASJC Scopus subject areas

  • Physiology
  • Sensory Systems
  • Physiology (medical)
  • Behavioral Neuroscience

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