title: Acid sensing by sweet and bitter taste neurons in Drosophila melanogaster.
abstract: Drosophila melanogaster can taste various compounds and separate them into few basic categories such as sweet, bitter and salt taste. Here we investigate mechanisms underlying acid detection in Drosophila and report that the fly displays strong taste aversion to common carboxylic acids. We find that acid tastants act by the activation of a subset of bitter neurons and inhibition of sweet neurons. Bitter neurons begin to respond at pH 5 and show an increase in spike frequency as the extracellular pH drops, which does not rely on previously identified chemoreceptors. Notably, sweet neuron activity depends on the balance of sugar and acid tastant concentrations. This is independent of bitter neuron firing, and allows the fly to avoid acid-laced food sources even in the absence of functional bitter neurons. The two mechanisms may allow the fly to better evaluate the risk of ingesting acidic foods and modulate its feeding decisions accordingly.
authors.affiliation: Biomedical Sciences Graduate Program, School of Medicine, 900 University Avenue, University of California-Riverside, CA 92521, USA.
authors.forename: Sandhya
authors.initials: S
authors.lastname: Charlu
authors.forename: Zev
authors.initials: Z
authors.lastname: Wisotsky
authors.forename: Adriana
authors.initials: A
authors.lastname: Medina
authors.forename: Anupama
authors.initials: A
authors.lastname: Dahanukar
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002241:Carbohydrates / Q000494:pharmacology*; D002264:Carboxylic Acids / Q000494:pharmacology*; D004331:Drosophila melanogaster / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D005638:Fruit / Q000737:chemistry; D005838:Genotype; D006851:Hydrochloric Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D050505:Mutant Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010812:Physical Stimulation; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D058618:Sensilla / Q000187:drug effects / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology; D013649:Taste / Q000187:drug effects*
chemical_list: D002241:Carbohydrates; D002264:Carboxylic Acids; D050505:Mutant Proteins; D043562:Receptors, G-Protein-Coupled; D013395:Sucrose; D006851:Hydrochloric Acid