Examination of the Molecular Mechanisms of Mosquito Odorant Receptors

蚊子的嗅觉系统已成为减少蚊媒疾病传播的一种手段，包括疟疾、登革出血热和西尼罗河脑炎。在这种感觉形式中，称为气味的挥发性化合物启动嗅觉感受器神经元(ON)的去极化，这些神经元位于嗅觉附件上的化学感觉感受器内。气味识别是通过多种机制来实现的，其中一种机制集中在嗅核表面表达的一系列气味受体(ORs)上。ORs被认为负责识别特定的气味并启动Orns的去极化。在蚊子中，基于OR的气味检测的功能单位由高度保守的辅助受体Orco和与气味特异性相关的发散性OR组成。以前人们认为昆虫的ORs与脊椎动物的ORs类似，是G蛋白偶联受体。然而，现在看来，昆虫OR复合体作为配体门控离子通道发挥作用，但目前的机制模型仍不清楚。此外，保守残基的功能意义还有待确定。拟议的研究将集中在主要的热带疟疾媒介蚊子冈比亚按蚊的OR。这项拟议的研究计划利用膜片钳电生理学来研究冈比亚按蚊OR(AGamOR)复合体的通道特性。此外，还将进行突变研究，以确定对AGamOR功能的各个方面至关重要的残基。虽然这些研究的实验重点将放在AGamOR的结构/功能上，但我们预计从拟议的实验中得出的分子模型将广泛适用于其他昆虫OR复合体。

The olfactory system of mosquitoes has been targeted as a means to decrease the spread of mosquito borne diseases, including malaria, dengue hemorrhagic fever, and West Nile encephalitis. In this sensory modality, volatile compounds known as odorants initiate depolarization of olfactory receptor neurons (ORNs), which are housed within chemosensory sensilla on the olfactory appendages. Odorant recognition is mediated through several mechanisms, one of which centers on a diverse family of odorant receptors (ORs) expressed on the surface of ORNs. ORs are believed to be responsible for recognizing specific odorants and initiating the depolarization of ORNs. In mosquitoes, the functional unit of OR-based odorant detection consists of a highly- conserved co-receptor, Orco, and a divergent OR associated with odorant specificity. It was previously believed that insect ORs acted as G-protein coupled receptors, similar to vertebrate ORs. However, it now appears that insect OR complexes function as ligand- gated ion channels, but the current mechanistic model remains unclear. Furthermore, the functional significance of conserved residues has yet to be determined. The proposed studies will focus on the ORs of the principal Afrotropical malaria vector mosquito, Anopheles gambiae. The proposed research plans to investigate the channel properties of various Anopheles gambiae OR (AgamOR) complexes using patch clamp electrophysiology. In addition, mutational studies to identify residues critical to various aspects of AgamOR function will also be performed. While the experimental focus of these studies will be on AgamOR structure/function, we expect that the molecular model derived from the proposed experiments will be broadly applicable to other insect OR complexes.