Distinct sweet taste receptor neurons in the legs of Drosophila

对于所有动物的生存来说，检测并引发对可口刺激的适当行为反应的能力是重要的。在果蝇中，以接触为基础的甜味化学物质的检测是由分布在苍蝇全身的味觉器官介导的，包括鼻子和腿。利用丰富多样的遗传技术，黑腹果蝇已经成为研究味觉系统结构和功能基本原理的极好的模型系统。然而，基本的问题仍然有待回答：不同的味觉感觉神经元是否具有特定的功能？果蝇大脑是如何计算甜味来引发食欲行为的？对糖的检测如何导致食欲行为的不同方面(例如，鼻子伸展，食欲强化)？我们的初步观察显示，形态上不同的一小部分颧骨感觉神经元在驱动对蔗糖的食欲反应方面特别重要。通过使用复杂的基因干预策略，我建议全面描述个别眼睑神经元的特征。为此，我们将产生转基因果蝇，使我们能够专门标记和操纵不同的鞑靼甜味受体，并识别它们在不同糖反应行为中的功能。作为探索果蝇甜味加工的细胞机制的第一步，我们的目标是有效地识别糖感觉神经元的下游神经元，并研究它们与味觉回路高阶成分的解剖联系。综上所述，这些实验将有助于构建果蝇糖反应的功能电路图。

The ability to detect and elicit appropriate behavioural responses to palatable stimuli is important for the survival of all animals. In Drosophila, contact-based detection of sweet chemical substances is mediated by gustatory organs that are distributed throughout the fly body, including the proboscis and legs. Taking advantage of a rich variety of genetic techniques, Drosophila melanogaster has served as an excellent model system to study basic principles of the structure and function of the gustatory system. Nevertheless, fundamental questions remain to be answered: Do different gustatory sensory neurons fulfill specific functions? How is sweet taste computed in the fly brain to elicit appetitive behaviour? How does detection of sugar lead to different aspects of appetitive behaviour (e.g. proboscis extension, appetitive reinforcement)?Our initial observations revealed that a small subset of morphologically distinct tarsal sensory neurons is particularly important in driving appetitive responses to sucrose. Using sophisticated genetic intervention strategies, I propose to comprehensively characterise individual tarsal neurons. To this end, we will generate transgenic flies that allow us to specifically label and manipulate distinct tarsal sweet taste receptors, and identify their functions in different sugar response behaviours. As a first step toward cellular mechanisms of sweet taste processing in the fly, we aim to efficiently identify downstream neurons of the sugar sensory neurons and investigate their anatomical connections to higher-order components of the taste circuit. Taken together, these experiments will contribute to the construction of functional circuit maps underlying sugar response in Drosophila.