Two antagonistic gustatory receptor neurons responding to sweet-salty and bitter taste in Drosophila.
In Drosophila, gustatory receptor neurons (GRNs) occur within hair-like structures called sensilla. Most taste sensilla house four GRNs, which have been named according to their preferred sensitivity to basic stimuli: water (W cell), sugars (S cell), salt at low concentration (L1 cell), and salt at high concentration (L2 cell). Labellar taste sensilla are classified into three types, l-, s-, and i-type, according to their length and location. Of these, l- and s-type labellar sensilla possess these four cells, but most i-type sensilla house only two GRNs. In i-type sensilla, we demonstrate here that the first GRN responds to sugar and to low concentrations of salt (10-50 mM NaCl). The second GRN detects a range of bitter compounds, among which strychnine is the most potent; and also to salt at high concentrations (over 400 mM NaCl). Neither type of GRN responds to water. The detection of feeding stimulants in i-type sensilla appears to be performed by one GRN with the combined properties of S+L1 cells, while the other GRN detects feeding inhibitors in a similar manner to bitter-sensitive L2 cells on the legs. These sensilla thus house two GRNs having an antagonistic effect on behavior, suggesting that the expression of taste receptors is segregated across them accordingly.
Hiroi
Makoto
M
Department of Biology, Graduate School of Sciences, Kyushu University, Ropponmatsu 4-2-1, Fukuoka 810-8560, Japan.
Meunier
Nicolas
N
Marion-Poll
Frédéric
F
Tanimura
Teiichi
T
D000200:Action Potentials / Q000187:drug effects; D000222:Adaptation, Physiological; D000818:Animals; D001522:Behavior, Animal; D001599:Berberine / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004327:Drinking Behavior / Q000187:drug effects; D004330:Drosophila; D029721:Drosophila Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D004347:Drug Interactions; D005260:Female; D008297:Male; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D011803:Quinine / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors / Q000502:physiology*; D012737:Sex Factors; D012965:Sodium Chloride / Q000494:pharmacology; D013331:Strychnine / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology; D013649:Taste / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D029721:Drosophila Proteins; D011956:Receptors, Cell Surface; C405956:gustatory receptor, Drosophila; D001599:Berberine; D002110:Caffeine; D012965:Sodium Chloride; D013395:Sucrose; D011803:Quinine; D013331:Strychnine