Molecular genetics of gustatory detection

摘要 该项目具有利用昆虫和昆虫之间味觉机制差异的长期潜力。 哺乳动物开发新的策略来控制感染数亿人的昆虫疾病媒介 每年。此外，这项研究还探索了昆虫和哺乳动物味觉之间意想不到的相似之处， 在进化上是保守的。这个项目将利用果蝇提供的大量工具， melanogaster，以解决接触化学感觉领域中的基本的、长期存在的问题。的 aims将采用通常多种方法的组合，包括电生理学，Ca 2+成像， 行为学、分子遗传学和细胞生物学方法。Aim 1测试了存在信号的想法 在检测低水平的苦味化合物中起作用的途径， 与哺乳动物的甜味、苦味和鲜味味觉传导的未被认识的相似性。品尝的能力 令人厌恶的化合物是生存所必需的，许多有毒化学物质的高水平是通过 所谓的“味觉感受器”，它是昆虫配体门控通道，不同于哺乳动物的味觉 受体。此外，TRP通道也被用于感知苦味化合物。目标1将检验以下观点： G蛋白偶联受体（GPCR）与苦味反应味觉受体中的TRP通道偶联 神经元，并使苍蝇能够感觉到低水平的有害化学物质。因此，尽管存在显著差异， 昆虫和人类之间的味觉接受的一些机制，目的1是定义一个GPCR/TRP依赖的 昆虫的味觉传导途径。然而，启动味觉传导的特异性GPCR 是非常出乎意料的。目标2涉及一种众所周知的高度保守的行为， 被低盐食物所吸引，拒绝高盐食物。第一个目标利用我们最近的发现， 低和高Na+味觉感受如何在味觉受体细胞中差异编码，从而 引起不同的行为反应。离子型受体（IR 76 b）是低盐感受器，而高盐感受器是高盐感受器。 受体仍然未知。目的2是确定高Na+受体，并解决它们是否形成多- 亚基阳离子通道另一种行为上保守但特征不明显的味觉模态是Ca 2 + 味道目的三是揭示赋予动物品尝Ca ~（2+）能力的神秘Ca ~（2+）受体。最后， 目的四是剖析食物质地影响口味的分子和细胞机制。 这将开辟重要的新领域，因为动物食物质地检测的分子基础还不清楚。 完全未被探索过目标4将测试通过果蝇检测食物硬度的想法 “跨膜通道样”（TMC）蛋白的同系物，其在哺乳动物中涉及作为跨膜通道的亚基。 通道复合体中的听觉毛细胞。总之，在昆虫和人类受体被 这些差异可以用来制定控制疾病媒介的战略。相反，聚焦 也揭示了进化上保守的味觉检测机制。

Abstract This project has the long-term potential to exploit the differences in taste mechanisms between insects and mammals to develop new strategies to control insect disease vectors that infect hundreds of millions of people annually. In addition, this research explores unexpected similarities between insect and mammalian taste that are evolutionarily conserved. This project will exploit the vast array of tools provided by the fruit fly, Drosophila melanogaster, to address fundamental, longstanding questions in the field of contact chemosensation. The aims will employ an usually diverse combination of approaches, including electrophysiology, Ca2+ imaging, behavior, molecular genetics and cell biological approaches. Aim 1 tests the idea that there exists a signaling pathway that functions in the detection of low levels of bitter compounds, and which bears previously unrecognized similarity to mammalian sweet, bitter and umami taste transduction. The capacity to taste aversive compounds is essential for survival, and high levels of many noxious chemicals are detected through so-called “gustatory receptors,” which are insect ligand-gated channels distinct from mammalian taste receptors. In addition, TRP channels are also employed to sense bitter compounds. Aim 1 will test the idea that a G-protein coupled receptor (GPCR) couples to a TRP channel in bitter responsive gustatory receptor neurons, and enables flies to sense noxious chemicals at low levels. Thus, despite the striking differences in some mechanisms of taste reception between insects and humans, aim 1 is to define a GPCR/TRP dependent taste transduction pathway in an insect. However, the specific GPCRs that appear to initiate taste transduction in the fly are highly unexpected. Aim 2 concerns a well-known and highly conserved behavior in which animals are attracted to low salt foods and reject foods with high salt. The first aim leverages our recent discovery as to how low and high Na+ taste perceptions are differentially encoded in gustatory receptor cells, and thereby induce distinct behavioral responses. An ionotropic receptor (IR76b) is the low salt sensor, but the high salt receptor remains unknown. Aim 2 is to define the high Na+ receptors, and address whether they form a multi- subunit cation channel. Another behaviorally conserved, but poorly characterized gustatory modality is Ca2+ taste. Aim 3 is to reveal the enigmatic Ca2+ receptors that endow animals with the ability to taste Ca2+. Finally, aim 4 is to dissect the molecular and cellular mechanism through which food texture affects taste preferences. This would break important new ground since the molecular basis for food texture detection in animals is as yet completely unexplored. Aim 4 will test the idea that the hardness of food is detected through the Drosophila homolog of “transmembrane channel-like” (TMC) proteins, which in mammals are implicated as subunits of a channel complex in auditory hair cells. In summary, in those cases in which insect and human receptors are distinct, the differences can be exploited to develop strategies to control disease vectors. Conversely, focusing on flies also offers to reveal evolutionarily conserved gustatory detection mechanisms.