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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Acid sensing by the Drosophila olfactory system. 2108 19

Animals across various phyla exhibit odor-evoked innate attraction behavior that is developmentally programmed. The mechanism underlying such behavior remains unclear because the odorants that elicit robust attraction responses and the neuronal circuits that mediate this behavior have not been identified. Here, we describe a functionally segregated population of olfactory sensory neurons (OSNs) and projection neurons (PNs) in Drosophila melanogaster that are highly specific to ammonia and amines, which act as potent attractants. The OSNs express IR92a, a member of the chemosensory ionotropic receptor (IR) family and project to a pair of glomeruli in the antennal lobe, termed VM1. In vivo calcium-imaging experiments showed that the OSNs and PNs innervating VM1 were activated by ammonia and amines but not by nonamine odorants. Flies in which the IR92a(+) neurons or IR92a gene was inactivated had impaired amine-evoked physiological and behavioral responses. Tracing neuronal pathways to higher brain centers showed that VM1-PN axonal projections within the lateral horn are topographically segregated from those of V-PN and DC4-PN, which mediate innate avoidance behavior to carbon dioxide and acidity, respectively, suggesting that these sensory stimuli of opposing valence are represented in spatially distinct neuroanatomic loci within the lateral horn. These experiments identified the neurons and their cognate receptor for amine detection, and mapped amine attractive olfactory inputs to higher brain centers. This labeled-line mode of amine coding appears to be hardwired to attraction behavior.
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PMID:Dedicated olfactory neurons mediating attraction behavior to ammonia and amines in Drosophila. 2350 67