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Remembering Nutrient Quality of Sugar in Drosophila

2011; Elsevier BV; Volume: 21; Issue: 9 Linguagem: Inglês

10.1016/j.cub.2011.03.032

1879-0445

Christopher J. Burke, Scott Waddell,

Olfactory and Sensory Function Studies

Taste is an early stage in food and drink selection for most animals [1Yarmolinsky D.A. Zuker C.S. Ryba N.J. Common sense about taste: From mammals to insects.Cell. 2009; 139: 234-244Abstract Full Text Full Text PDF PubMed Scopus (489) Google Scholar, 2Dethier V.G. The Hungry Fly: A Physiological Study of the Behaviour Associated with Feeding. Harvard University Press, Cambridge, MA1976Google Scholar]. Detecting sweetness indicates the presence of sugar and possible caloric content. However, sweet taste can be an unreliable predictor of nutrient value because some sugars cannot be metabolized. In addition, discrete sugars are detected by the same sensory neurons in the mammalian [3Zhao G.Q. Zhang Y. Hoon M.A. Chandrashekar J. Erlenbach I. Ryba N.J. Zuker C.S. The receptors for mammalian sweet and umami taste.Cell. 2003; 115: 255-266Abstract Full Text Full Text PDF PubMed Scopus (887) Google Scholar] and insect [4Wang Z. Singhvi A. Kong P. Scott K. Taste representations in the Drosophila brain.Cell. 2004; 117: 981-991Abstract Full Text Full Text PDF PubMed Scopus (320) Google Scholar, 5Thorne N. Chromey C. Bray S. Amrein H. Taste perception and coding in Drosophila.Curr. Biol. 2004; 14: 1065-1079Abstract Full Text Full Text PDF PubMed Scopus (276) Google Scholar] gustatory systems, making it difficult for animals to readily distinguish the identity of different sugars using taste alone [6Breslin P.A. Kemp S. Beauchamp G.K. Single sweetness signal.Nature. 1994; 369: 447-448Crossref PubMed Scopus (40) Google Scholar, 7Dotson C.D. Spector A.C. Behavioral discrimination between sucrose and other natural sweeteners in mice: Implications for the neural coding of T1R ligands.J. Neurosci. 2007; 27: 11242-11253Crossref PubMed Scopus (29) Google Scholar, 8Masek P. Scott K. Limited taste discrimination in Drosophila.Proc. Natl. Acad. Sci. USA. 2010; 107: 14833-14838Crossref PubMed Scopus (73) Google Scholar]. Here we used an appetitive memory assay in Drosophila [9Tempel B.L. Bonini N. Dawson D.R. Quinn W.G. Reward learning in normal and mutant Drosophila.Proc. Natl. Acad. Sci. USA. 1983; 80: 1482-1486Crossref PubMed Scopus (273) Google Scholar, 10Krashes M.J. Waddell S. Rapid consolidation to a radish and protein synthesis-dependent long-term memory after single-session appetitive olfactory conditioning in Drosophila.J. Neurosci. 2008; 28: 3103-3113Crossref PubMed Scopus (177) Google Scholar, 11Colomb J. Kaiser L. Chabaud M.A. Preat T. Parametric and genetic analysis of Drosophila appetitive long-term memory and sugar motivation.Genes Brain Behav. 2009; 8: 407-415Crossref PubMed Scopus (66) Google Scholar] to investigate the contribution of palatability and relative nutritional value of sugars to memory formation. We show that palatability and nutrient value both contribute to reinforcement of appetitive memory. Nonnutritious sugars formed less robust memory that could be augmented by supplementing with a tasteless but nutritious substance. Nutrient information is conveyed to the brain within minutes of training, when it can be used to guide expression of a sugar-preference memory. Therefore, flies can rapidly learn to discriminate between sugars using a postingestive reward evaluation system, and they preferentially remember nutritious sugars.