Molecular neurophysiology of neural mechanisms of taste reception in Drosophila

(1)我们发现果蝇接受糖的味觉部分需要一个G蛋白伽马亚基。G蛋白伽马亚单位的基因主要在味觉感受器神经元中表达。通过利用Ga14/UAS系统靶向抑制Gel-Gamma亚单位表达细胞，降低了果蝇对蔗糖的行为和电生理反应。我们还证明了GCL伽马零突变体对糖的反应降低。(2)昆虫有专门的味觉细胞对水做出反应。我们发现了一个Ga14增强子陷阱菌株，在该菌株中，GAL4在标签上每个感受器的单个味觉感受器细胞中表达。这些细胞的神经功能通过表达shibire[Ts1]而被阻断，行为测试和电生理记录表明它们是水味细胞。我们发现水感受器细胞的轴突投射到食道下神经节的特定区域。(3)果蝇性信息素是挥发性的或非挥发性的。嗅觉神经元感知挥发性信息素，我们发现表达Gr66a标记的味觉神经元对男性特有的非挥发性信息素--7-二十三碳油有反应。这是通过一种新开发的钨电极记录方法完成的。在求爱过程中，7-二十三碳烯可能是通过鞑靼味觉感受器感受到的，我们观察到表达Gr66a的神经元在鞑靼的投射模式。通过使用FLP-Out技术，我们产生了镶嵌苍蝇，其中只有少数表达Gr66a的神经元可以被标记并观察它们的投射模式。结果表明，感受性信息素的感受器表达Gr66a的神经元与参与取食行为的其他感受器的投射模式不同。我们认为，来自Gr66a表达神经元的信息根据它们相关的行为被发送到不同的区域。

(1) We showed that a G-protein gamma subunit is partially required for sugar taste reception in Drosophila. The gene for the G-protein gamma subunit is expressed mainly in one of the gustatory receptor neurons. Behavioral and electrophysiological responses of the flies to sucrose were reduced by the targeted neural suppression of Gel gamma subunit-expressing cells utilizing Ga14/UAS system. We also demonstrated that responses to sugars were lowered in Gcl gamma null mutant.(2) Insects have specialized gustatory cells responding to water. We found a Ga14 enhancer trap strain in which GAL4 is expressed in a single taste receptor cell in each sensillum on the labellum. The neural function of these cells was blocked by expressing shibire [ts1] and behavioral tests and electrophysiological recordings indicated that they are the water taste cells. We show that axons of the water receptor cells project to a specific region in the subesophageal ganglion.(3) Sex pheromones are volatile or non-volatile in Drosophila. Volatile pheromones are sensed by olfactory neurons and we found that labellar Gr66a-expressing taste neurons respond to a male specific non-volatile pheromone, 7-tricosene. This was done by a newly developed tungsten electrode recording method. 7-Tricosene is probably sensed by tarsal taste sensilla during courtship and we observed projection patterns from Gr66a-expressing neurons in tarsi. By using a Flp-out technique, we generated mosaic flies in which only a few Gr66a-expressing neurons can be labeled and observed their projection patterns. Results showed that projection patterns of Gr66a-expressing neurons from sensilla that might sense the sex-pheromone and those from other sensilla that are involved in feeding behavior are different. We suggest that information from Gr66a-expressing neurons is sent to a different region depending on their related behavior.