NSF-BSF: Exploiting the evolution of odorant discrimination in ants to decipher the olfactory code

生命的特性之一是能够探测和响应环境刺激，这在动物身上是由复杂的感官系统促进的，如视觉、听觉和嗅觉。然而，与视觉和听觉相比，我们对嗅觉空间和气味辨别进化的理解存在很大差距。这个项目通过使用蚂蚁作为一种新的嗅觉模型系统来帮助破译嗅觉密码，来研究气味和它们特定的受体之间的相互作用。蚂蚁依靠它们的嗅觉相互交流，并区分群体成员和非群体成员。为此，它们使用出现在它们身体表面的化学物质，这些化学物质提供了大量的化学“词汇”。它们在蚂蚁体内的重要性反映在对这些化合物敏感的大量嗅觉受体上。辨别生物测试、对这些化合物的嗅觉受体调谐分析、受体进化分析以及嗅觉受体的结构/功能分析将破译如何在受体水平上提高化合物的辨别能力。这项研究的结果将有助于填补我们对嗅觉和通过嗅觉进行交流的基本理解的空白。该项目将用于培训来自代表性不足群体的本科生和研究生以及高中生，使他们掌握现代行为分析和实验方法。将制作一款关于嗅觉识别的教育游戏，可以整合到高中生的课堂课程中。气味识别的机制仍然是动物行为感觉生理学中的一个具有挑战性的问题，包括感受器水平和高级大脑中枢对嗅觉信息的处理。该项目侧重于受体水平上的气味识别机制，并使用角质层碳氢化合物的化合物基团来实现这一目的。角质层碳氢化合物以长链碳氢化合物的复杂混合物存在于几乎所有昆虫的身体表面，并被用于许多重要的环境中，包括配偶交流和群体歧视，这需要根据其角质层碳氢化合物分布对个体进行分类。在群居昆虫中，对非群居成员的歧视对于避免任何形式的群居剥削尤为重要。因此，在群居昆虫中对这些辨别能力的选择是可望的。我们将利用蚂蚁丰富的嗅觉感受器来识别识别角质层碳氢化合物的关键受体。这些烃敏感嗅觉感受器的调谐曲线将被测定和比较。这些分析将与生物化验相结合，以确定区分个别碳氢化合物的差异。在蚂蚁受体系统中丰富的表皮碳氢敏感嗅觉受体，以及在基因复制后许多密切相关的嗅觉受体的存在，为结构/功能分析提供了基础。结合对密切相关的嗅觉受体配体特异性的功能分析和受体分子的三维重建，将确定分子序列变化如何导致嗅觉空间的扩大。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

One of the properties of life is the ability to detect and respond to environmental stimuli, which is facilitated in animals by sophisticated sensory systems such as vision, audition, and olfaction. However, compared to vision and audition, large gaps exist in our understanding of olfactory space and the evolution of odor discrimination. This project investigates the interplay between odors and their specific receptors by using ants as a new olfactory model system to help decipher the olfactory code. Ants depend on their olfactory sense to communicate with each other and to differentiate between colony members or non-members. For this purpose, they use chemicals that occur on their body surface and that provide a large vocabulary of chemical “words”. Their importance in ants is reflected in the large repertoire of olfactory receptors that are sensitive to these compounds. Discrimination bioassays, analyses of olfactory receptor tuning to these compounds, analyses of receptor evolution and a structure/function analysis of the olfactory receptors will decipher how discrimination of compounds can be improved at the receptor level. The outcome of this research will help fill a gap in our fundamental understanding of olfaction and communication through olfaction. The project will be used to train undergraduate and graduate students as well as high-school students from underrepresented groups in modern approaches of behavioral analysis and experimentation. An educational game about olfactory discrimination will be produced that can be integrated into classroom lessons for high school students.Understanding the mechanisms of odorant discrimination is still a challenging problem in the sensory physiology of animal behavior that includes the receptor level and the processing of olfactory information in higher brain centers. This project focuses on mechanisms of odorant discrimination at the receptor level and uses the compound group of cuticular hydrocarbons for this purpose. Cuticular hydrocarbons occur as complex mixtures of long-chain hydrocarbons on the body surface of almost all insects and are used in many important contexts, including mate communication and colony discrimination, which require classification of individuals based on their cuticular hydrocarbon profiles. In social insects, discrimination against non-colony members is especially important to avoid any form of colony exploitation. Therefore, strong selection on these discrimination abilities is expected in social insects. The rich olfactory receptor repertoire in ants will be exploited to identify key receptors in the discrimination of cuticular hydrocarbons. Tuning curves of these hydrocarbon sensitive olfactory receptors will be determined and compared. These analyses will be combined with bioassays to determine differences in the discrimination of individual hydrocarbon compounds. The abundance of cuticular hydrocarbon sensitive olfactory receptors in the receptor phylogeny of ants, and the presence of many closely related olfactory receptors following gene duplications, provide the foundation of structure/function analyses. The combination of functional analyses of ligand specificity of closely related olfactory receptors with the three-dimensional reconstruction of the receptor molecules will establish how molecular sequence changes lead to the expansion of olfactory space.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.