The role of insect sweet taste receptors in detecting sweet and bitter compounds

描述（由申请人提供）：所有昆虫，包括蚊子，必须能够确定潜在食物来源的适口性。这使得使用糖饵诱捕器成为控制蚊媒疾病传播的有效方法。黑腹蝇是一种研究味觉的模式生物，因为这种苍蝇可以探测到各种各样的化合物，但其神经生理学相对简单。味觉受体（Gr）在味觉神经元中表达，该家族的成员通过遗传分析与甜味或苦味的检测有关。然而，在异源表达系统中表达这些受体的成功很少，这导致在了解单个昆虫Grs的功能特性以及鉴定功能性昆虫味觉受体的组成方面存在关键空白。这代表了一个重要的问题，因为Grs属于一个在昆虫和非昆虫节肢动物中高度保守的家族。为了解决这个问题，我们将使用两种平行的方法来研究果蝇和蚊子的甜味受体，利用我们设计的一种新的体内表达系统来解码果蝇味觉受体蛋白。使用这种方法，我已经确定了黑腹d.m anogaster中每个假定的甜味受体的糖反应谱。此外，使用混合刺激的录音，我发现果蝇的甜味感受器直接被咬生物碱抑制。这种机制可能是进化保守的，因为猕猴的唇瓣甜味神经元。冈比亚和Ae。埃及伊蚊也受到生物碱的抑制。该项目具有创新性，因为这是第一个成功在体内异源神经元中表达甜味受体的报告。假设是黑腹龙舌兰和安。冈比亚虫可以单独对一组独特的甜化合物作出反应，并被一组独特的生物碱抑制。基本原理是，通过了解昆虫味觉感受器如何检测

DESCRIPTION (provided by applicant): All insects, including mosquitoes, must be able to determine the palatability of potential food sources. This makes the use of sugar-baited traps an effective method to control the spread of mosquito borne illnesses. D. melanogaster is a model organism to study gustation because the fly can detect a broad range of compounds but has a relatively simple neurophysiology. Gustatory receptors (Gr) are expressed in taste neurons and members of this family are implicated in the detection of sweet or bitter tastants by genetic analyses. However, there has been little success in expressing these receptors in heterologous expression systems, which has led to a critical gap in understanding the functional properties of individual insect Grs, as well as in identifying the composition of a functional insect taste receptor. This represents an important problem because Grs belong to a family that is highly conserved in insects and non-insect arthropods. To address this problem, we will use two parallel approaches to study sweet taste receptors in Drosophila and mosquitoes, taking advantage of a novel in vivo expression system that we have designed for decoding Drosophila gustatory receptor proteins. Using this approach, I have identified sugar response profiles of each of the putative sweet taste receptors in D. melanogaster. Moreover, using recordings with mixed stimuli I have found that sweet taste receptors in Drosophila are directly inhibited by bitte alkaloids. This mechanism may be evolutionarily conserved since labellar sweet taste neurons in An. gambiae and Ae. aegypti are inhibited by alkaloids as well. The proposed project is innovative because this is the first report of successful expression of sweet taste receptors in a heterologous neuron in vivo. The hypothesis is that each receptor in both D. melanogaster and An. gambiae can individually respond to a unique set of sweet compounds and is inhibited by a distinct set of alkaloids. The rationale is that by understanding how insect taste receptors detect attractive and aversive compounds, we can then screen for novel compounds that can be used in insect control strategies. My objectives will be achieved via two specific aims: (1) Identify an characterize the functional properties of trehalose receptors in Drosophila, and (2) Identify and characterize the functional properties of select mosquito sweet taste receptors. This project will reveal the composition and response properties of a functional trehalose receptor. My studies will lay the foundation to probe structure-function relationships of sweet receptor's in Drosophila and An. gambiae in terms of detection of chemicals of both sweet and bitter categories with opposing effects on receptor activity. The significance of the proposed project is that it will advance our understanding of a highly conserved insect chemoreceptor family and establish a system to study insect gustatory receptor function by ectopic expression. The proposed project will enhance my training to be an independent researcher and allow me to use engineering principles to solve biological questions about sweet receptors. I will also gain experience in working with the disease vector An. gambiae.