title: The molecular basis of sugar sensing in Drosophila larvae.
abstract: Evaluation of food chemicals is essential to make appropriate feeding decisions. The molecular genetic analysis of Gustatory receptor (Gr) genes and the characterization of the neural circuits that they engage has led to a broad understanding of taste perception in adult Drosophila [1, 2]. For example, eight relatively highly conserved members of the Gr gene family (Gr5a, Gr61a, and Gr64a-f), referred to as sugar Gr genes, are thought to be involved in sugar taste in adult flies [3-8], while the majority of the remaining Gr genes are likely to encode bitter taste receptors [9-11], albeit some function as pheromone [12-14] and carbon dioxide [15, 16] receptors. In contrast to the adult fly, relatively little is known about the cellular and molecular basis of taste perception in larvae. Here, we identify Gr43a, which was recently shown to function as a hemolymph fructose sensor in adult flies [17], as the major larval sugar receptor. We show that it is expressed in taste neurons, proventricular neurons, as well as sensory neurons of the brain. Larvae lacking Gr43a fail to sense sugars, while larvae mutant for all eight sugar Gr genes exhibit no obvious defect. Finally, we show that brain neurons are necessary and sufficient for sensing all main dietary sugars, which probably involves a postingestive mechanism of converting carbohydrates into fructose.
authors.affiliation: Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M Health Science Center, College Station, TX 77843, USA.
authors.forename: Dushyant
authors.initials: D
authors.lastname: Mishra
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Miyamoto
authors.forename: Yohannes H
authors.initials: YH
authors.lastname: Rezenom
authors.forename: Alex
authors.initials: A
authors.lastname: Broussard
authors.forename: Ahmet
authors.initials: A
authors.lastname: Yavuz
authors.forename: Jesse
authors.initials: J
authors.lastname: Slone
authors.forename: David H
authors.initials: DH
authors.lastname: Russell
authors.forename: Hubert
authors.initials: H
authors.lastname: Amrein
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001921:Brain / Q000166:cytology / Q000502:physiology*; D002241:Carbohydrates / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000502:physiology*; D007814:Larva / Q000378:metabolism / Q000502:physiology; D009474:Neurons / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D013649:Taste / Q000502:physiology
chemical_list: D002241:Carbohydrates; D029721:Drosophila Proteins; C577647:Gr43a protein, Drosophila; D011956:Receptors, Cell Surface