Functional analysis of insect taste receptors

描述(由申请人提供)：检测各种化学物质并利用这些信息做出喂食决定的能力是从人类到昆虫的味觉系统的一个决定性特征。在果蝇中，味觉受体(Gr)基因大家族编码不同的受体，这些受体在味觉神经元中表达。尽管我们一直在努力，但我们对昆虫中单个GR蛋白的配基反应谱知之甚少。GR蛋白是一个新的家族，只与昆虫气味受体(OR)蛋白有较远的亲缘关系，因此缺乏与同等基团进行结构或功能比较的优势。然而，昆虫和节肢动物排他性的相同特征，使GRS成为开发新的昆虫控制策略的有吸引力的目标。在初步研究中，我们已经开发出一种体内功能 一种表达系统，用于识别单个昆虫GRS的响应特性。这项建议的首要目标是阐明果蝇和疟疾按蚊冈比亚按蚊个体味觉受体的功能特性，以及它们在指导取食行为中的作用。我们建议利用我们的异位表达系统来系统地表征果蝇和蚊子所选择的味觉受体的调谐曲线。这些实验旨在揭示GR功能的基本特征，包括单个受体的激活和抑制曲线，受体之间功能重叠的程度，以及受体序列和功能之间的关系。解决这些问题的方法将是：1)鉴定果蝇内部表达的味觉受体的调谐曲线，并通过遗传分析评估它们在取食行为中的作用；2)表征果蝇甜味受体与苦味者之间新的跨通道相互作用，并研究甜味神经元抑制在取食行为中的功能作用；3)鉴定可能的甜味受体的激活物和抑制物。并描述了蚊子鼻子内源性甜味神经元的反应曲线。这项研究具有创新性，因为它采用了一种新的体内异位表达系统来解码Gr功能，并将其与味觉功能的分子遗传学、电生理和行为分析相结合。这项研究意义重大，因为对GR基因的功能分析将有助于我们理解味觉在不同受体系统中编码的基本原理，以及味觉检测机制如何转化为食物选择。此外，我们的研究将阐明蚊子体内糖分检测的分子和细胞机制，这可能适用于改进用于蚊子监测和控制策略的糖饵诱捕器。好了！

DESCRIPTION (provided by applicant): The ability to detect various chemicals and to use this information to make feeding decisions is a defining feature of the taste system from humans to insects. In Drosophila, a large family of Gustatory receptor (Gr) genes encodes divergent receptors that are expressed in taste neurons. Despite ongoing efforts, we know little about the ligand response profiles of individual Gr proteins in any insect. Gr proteins represent a novel family, distantly related only to insect Odorant receptor (Or) proteins, and thus lack the advantage of structural or functional comparisons with equivalent groups. The same feature of exclusivity in insects and arthropods, however, makes Grs attractive targets for developing novel strategies of insect control. In preliminary studies, we have developed an in vivo functional expression system in which to identify the response properties of individual insect Grs. The overarching objective of this proposal is to elucidate functional properties of individual taste receptors in Drosophila and the malaria mosquito Anopheles gambiae, and their role in instructing feeding behavior. We propose to systematically characterize the tuning profiles of selected taste receptors of the fruit fly and the mosquito by taking advantage of our ectopic expression system. The experiments are designed to reveal fundamental features of Gr function including the activation and inhibition profiles of individual receptors, the extent of functional overlap between receptors, and the relationship between receptor sequence and function. The approach to address these questions will be to: 1) Identify the tuning profiles of internally expressed Drosophila taste receptors, and evaluate their roles in feeding behavior by genetic analysis, 2) Characterize novel cross-modality interactions between Drosophila sweet taste receptors and bitter tastants, and examine the functional role of sweet taste neuron inhibition in feeding behavior, and 3) Identify activators and inhibitors of putative sweet taste receptors of An. gambiae and characterize the response profiles of endogenous sweet taste neurons in the mosquito proboscis. The proposed research is innovative because it employs a novel in vivo ectopic expression system for decoding Gr function and combines it with molecular genetics, electrophysiological, and behavioral analyses of gustatory function. The research is significant because functional analysis of Gr genes will contribute to our understanding of the fundamental principles by which tastants are encoded across a diverse repertoire of receptors and how mechanisms of tastant detection translate to food selection. Additionally, our studies will shed light on molecular and cellular mechanisms of sugar detection in mosquitoes, which may be applicable for improving sugar-baited traps that are used in mosquito surveillance and control strategies. !