Marella Sunanda, Fischler Walter, Kong Priscilla, Asgarian Sam, Rueckert Erroll, Scott Kristin
Department of Molecular and Cell Biology, Helen Wills Neuroscience Institute, 291 Life Sciences Addition, University of California, Berkeley, Berkeley, California 94720, USA.
Neuron. 2006 Jan 19;49(2):285-95. doi: 10.1016/j.neuron.2005.11.037.
The sense of taste allows animals to distinguish nutritious and toxic substances and elicits food acceptance or avoidance behaviors. In Drosophila, taste cells that contain the Gr5a receptor are necessary for acceptance behavior, and cells with the Gr66a receptor are necessary for avoidance. To determine the cellular substrates of taste behaviors, we monitored taste cell activity in vivo with the genetically encoded calcium indicator G-CaMP. These studies reveal that Gr5a cells selectively respond to sugars and Gr66a cells to bitter compounds. Flies are attracted to sugars and avoid bitter substances, suggesting that Gr5a cell activity is sufficient to mediate acceptance behavior and that Gr66a cell activation mediates avoidance. As a direct test of this hypothesis, we inducibly activated different taste neurons by expression of an exogenous ligand-gated ion channel and found that cellular activity is sufficient to drive taste behaviors. These studies demonstrate that taste cells are tuned by taste category and are hardwired to taste behaviors.
味觉使动物能够区分营养物质和有毒物质，并引发对食物的接受或回避行为。在果蝇中，含有Gr5a受体的味觉细胞对于接受行为是必需的，而含有Gr66a受体的细胞对于回避行为是必需的。为了确定味觉行为的细胞基础，我们用基因编码的钙指示剂G-CaMP在体内监测味觉细胞的活性。这些研究表明，Gr5a细胞对糖类有选择性反应，而Gr66a细胞对苦味化合物有反应。果蝇被糖类吸引并回避苦味物质，这表明Gr5a细胞的活性足以介导接受行为，而Gr66a细胞的激活介导回避行为。作为对这一假设的直接测试，我们通过表达外源性配体门控离子通道来诱导激活不同的味觉神经元，发现细胞活性足以驱动味觉行为。这些研究表明，味觉细胞根据味觉类别进行调节，并与味觉行为有固定联系。
