Acid sensing by the Drosophila olfactory system

Nature. 2010 Dec 2;468(7324):691-5. doi: 10.1038/nature09537. Epub 2010 Nov 17.


The odour of acids has a distinct quality that is perceived as sharp, pungent and often irritating. How acidity is sensed and translated into an appropriate behavioural response is poorly understood. Here we describe a functionally segregated population of olfactory sensory neurons in the fruitfly, Drosophila melanogaster, that are highly selective for acidity. These olfactory sensory neurons express IR64a, a member of the recently identified ionotropic receptor (IR) family of putative olfactory receptors. In vivo calcium imaging showed that IR64a+ neurons projecting to the DC4 glomerulus in the antennal lobe are specifically activated by acids. Flies in which the function of IR64a+ neurons or the IR64a gene is disrupted had defects in acid-evoked physiological and behavioural responses, but their responses to non-acidic odorants remained unaffected. Furthermore, artificial stimulation of IR64a+ neurons elicited avoidance responses. Taken together, these results identify cellular and molecular substrates for acid detection in the Drosophila olfactory system and support a labelled-line mode of acidity coding at the periphery.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetic Acid / analysis
  • Acetic Acid / pharmacology
  • Acids / analysis*
  • Acids / pharmacology
  • Animals
  • Arthropod Antennae / anatomy & histology
  • Arthropod Antennae / cytology
  • Arthropod Antennae / drug effects
  • Arthropod Antennae / innervation
  • Calcium Signaling / drug effects
  • Carbon Dioxide / metabolism
  • Carbonic Acid / metabolism
  • Carbonic Acid / pharmacology
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / anatomy & histology
  • Drosophila melanogaster / cytology
  • Drosophila melanogaster / drug effects
  • Drosophila melanogaster / physiology*
  • Maze Learning
  • Odorants / analysis*
  • Olfactory Pathways / cytology
  • Olfactory Pathways / drug effects
  • Olfactory Pathways / physiology*
  • Receptors, Ionotropic Glutamate / metabolism
  • Receptors, Odorant / metabolism
  • Sensilla / cytology
  • Sensory Receptor Cells / drug effects
  • Sensory Receptor Cells / metabolism
  • Temperature


  • Acids
  • Drosophila Proteins
  • IR64a protein, Drosophila
  • Receptors, Ionotropic Glutamate
  • Receptors, Odorant
  • Carbon Dioxide
  • Carbonic Acid
  • Acetic Acid