Sugar receptors in the honeybee

对糖的感知和评估在蜜蜂的生活中起着核心作用。蔗糖、果糖和葡萄糖等糖类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，而蜂巢内的看护蜜蜂在准备幼雏食物时必须考虑蜂蜜的质量。除此之外，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，在联想学习和记忆测试中，糖反应能力强的人比糖反应能力弱的人表现得更好。蔗糖反应阈值的个体差异甚至与蜂群中复杂的社会组织有关。与丰富的糖感知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评估中的功能知之甚少。这个项目的目标是确定所有蜜蜂糖受体在系统的不同水平上的功能。我们的目标是：(1)从药理学上表征三种假定的蜜蜂糖受体及其剪接变体，并确定涉及糖感知的信号级联；(2)了解不同味觉器官和组织在糖刺激评估中的作用；(3)将对不同糖的行为反应和选定糖受体的mRNA表达与蜜蜂群体中的劳动分工联系起来。由于蜜蜂的糖受体相对较少，它有可能成为了解昆虫和其他昆虫对糖感知的模型。由于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、学习和劳动分工之间的复杂关系至关重要。

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.