Sugar receptors in the honeybee

对糖的感知和评价在蜜蜂的生活中起着核心作用。蔗糖、果糖和葡萄糖等糖是蜜蜂的主要食物来源。觅食蜜蜂必须评估花蜜来源的质量，而蜂箱内的哺乳蜜蜂在准备蜂巢食物时必须考虑蜂蜜的质量。最重要的是，个体对糖的反应是蜜蜂生理状态的关键指标。例如，我的团队和其他人的实验表明，蔗糖反应性高的人在联想学习和记忆测试中的表现比那些蔗糖反应性低的人更好。蔗糖反应阈值的个体差异甚至与蜜蜂群体中复杂的社会组织有关。与丰富的糖感行为数据形成鲜明对比的是，令人惊讶的是，人们对蜜蜂糖受体及其在糖分评估中的功能知之甚少。该项目的目标是确定系统不同水平上的所有蜜蜂糖受体的功能。我们的目标是(1)从药理学的角度对三种可能的蜜蜂糖受体及其剪接变异体进行表征，并确定参与糖感受的信号级联反应；(2)了解不同的味觉器官和组织在评估糖刺激中的作用；(3)将蜜蜂对不同糖的行为反应和选定的糖受体的mRNA表达与蜜蜂群体中的分工联系起来。由于蜜蜂的糖受体数量相对较少，蜜蜂有可能成为理解昆虫和其他昆虫中糖感受的模型。由于蜜蜂糖感知的个体差异与蜜蜂的多种行为相关，因此我们在分子水平上对糖感知的分析对于理解蜜蜂群体中糖感知、学习和分工之间的复杂关系将是至关重要的。

The perception and evaluation of sugars plays a central role in the life of a honeybee. Sugars such as sucrose, fructose and glucose are the main food source of honeybees. Forager bees have to evaluate the quality of a nectar source, while nurse bees inside the hive have to account for the honey quality when preparing brood food. On top of this, individual responsiveness to sugar is a pivotal indicator of the physiological state of a honeybee. Experiments of my group and others have shown, for example, that individuals with high sucrose responsiveness perform better in associative learning and memory tests than those with low sucrose responsiveness. Individual differences in sucrose response thresholds even correlate with the intricate social organization in a honeybee colony. In sharp contrast to the wealth of behavioural data on sugar sensing, surprisingly little is known about honeybee sugar receptors and their function in the evaluation of sugar.The goal of this project is to identify the function of all honeybee sugar receptors on different levels of the system. We aim to (1) characterize the three putative honeybee sugar receptors and their splice variants pharmacologically and to identify the signalling cascades involved in sugar perception,(2) understand the role of different taste organs and tissues in the evaluation of a sugar stimulus,(3) relate the behavioural response to different sugars and mRNA expression of selected sugar receptors to division of labour in a honeybee colony.With the comparatively small number of sugar receptors, the honeybee has the potential to become a model for understanding sugar perception in insects and beyond. Because individual differences in sugar perception correlate with multiple behaviours in the honeybee, our analysis of sugar perception on the molecular level will be of paramount importance for understanding the complex relationships between sugar perception, learning and division of labour in a honeybee colony.