Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Génopode Building, Lausanne, CH-1015, Switzerland.
Centre for Neural Circuits and Behaviour, University of Oxford, Tinsley Building, Mansfield Road, Oxford, OX1 3SR, United Kingdom.
Nat Commun. 2018 Oct 12;9(1):4252. doi: 10.1038/s41467-018-06453-1.
Through analysis of the Drosophila ionotropic receptors (IRs), a family of variant ionotropic glutamate receptors, we reveal that most IRs are expressed in peripheral neuron populations in diverse gustatory organs in larvae and adults. We characterise IR56d, which defines two anatomically-distinct neuron classes in the proboscis: one responds to carbonated solutions and fatty acids while the other represents a subset of sugar- and fatty acid-sensing cells. Mutational analysis indicates that IR56d, together with the broadly-expressed co-receptors IR25a and IR76b, is essential for physiological responses to carbonation and fatty acids, but not sugars. We further demonstrate that carbonation and fatty acids both promote IR56d-dependent attraction of flies, but through different behavioural outputs. Our work provides a toolkit for investigating taste functions of IRs, defines a subset of these receptors required for carbonation sensing, and illustrates how the gustatory system uses combinatorial expression of sensory molecules in distinct neurons to coordinate behaviour.
通过对果蝇离子型受体（IRs）的分析，一种变体离子型谷氨酸受体家族，我们揭示了大多数 IRs 在幼虫和成虫的各种味觉器官中的外围神经元群体中表达。我们对 IR56d 进行了特征描述，它在触角中定义了两个解剖上不同的神经元类群：一类对碳酸溶液和脂肪酸有反应，而另一类则代表了糖和脂肪酸感应细胞的一个子集。突变分析表明，IR56d 与广泛表达的共受体 IR25a 和 IR76b 一起，对于对碳酸化和脂肪酸的生理反应是必需的，但不是糖。我们进一步证明，碳酸化和脂肪酸都促进了 IR56d 依赖性的苍蝇吸引，但通过不同的行为输出。我们的工作为研究 IRs 的味觉功能提供了一个工具包，定义了一组这些受体，这些受体是对碳酸化感应所必需的，并说明了味觉系统如何使用不同神经元中感觉分子的组合表达来协调行为。
