title: Acid sensing by the Drosophila olfactory system.
abstract: 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.
authors.affiliation: Molecular Neurobiology Program, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University, School of Medicine, New York, New York 10016, USA.
authors.forename: Minrong
authors.initials: M
authors.lastname: Ai
authors.forename: Soohong
authors.initials: S
authors.lastname: Min
authors.forename: Yael
authors.initials: Y
authors.lastname: Grosjean
authors.forename: Charlotte
authors.initials: C
authors.lastname: Leblanc
authors.forename: Rati
authors.initials: R
authors.lastname: Bell
authors.forename: Richard
authors.initials: R
authors.lastname: Benton
authors.forename: Greg S B
authors.initials: GS
authors.lastname: Suh
mesh_terms: D019342:Acetic Acid / Q000032:analysis / Q000494:pharmacology; D000143:Acids / Q000032:analysis* / Q000494:pharmacology; D000818:Animals; D057506:Arthropod Antennae / Q000033:anatomy & histology / Q000166:cytology / Q000187:drug effects / Q000294:innervation; D020013:Calcium Signaling / Q000187:drug effects; D002245:Carbon Dioxide / Q000378:metabolism; D002255:Carbonic Acid / Q000378:metabolism / Q000494:pharmacology; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018782:Maze Learning; D009812:Odorants / Q000032:analysis*; D009833:Olfactory Pathways / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D058468:Receptors, Ionotropic Glutamate / Q000378:metabolism; D018035:Receptors, Odorant / Q000378:metabolism; D058618:Sensilla / Q000166:cytology; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000378:metabolism; D013696:Temperature
chemical_list: D000143:Acids; D029721:Drosophila Proteins; C554857:IR64a protein, Drosophila; D058468:Receptors, Ionotropic Glutamate; D018035:Receptors, Odorant; D002245:Carbon Dioxide; D002255:Carbonic Acid; D019342:Acetic Acid