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

生命的特性之一是检测和响应环境刺激的能力，这在动物中通过复杂的感觉系统如视觉，听觉和嗅觉来促进。然而，与视觉和听觉相比，我们对嗅觉空间的理解和气味辨别的进化存在很大的差距。本研究以蚂蚁为嗅觉模型系统，探讨气味与其特定受体之间的相互作用，以帮助破译嗅觉密码。蚂蚁依靠它们的嗅觉来相互交流，并区分群体成员和非成员。为了这个目的，他们使用的化学物质发生在他们的身体表面，并提供了大量的化学“词汇”。它们在蚂蚁中的重要性反映在对这些化合物敏感的嗅觉受体的大库中。辨别生物测定、嗅觉受体对这些化合物的调节分析、受体进化分析和嗅觉受体的结构/功能分析将解释如何在受体水平上改善化合物的辨别。这项研究的结果将有助于填补我们对嗅觉和嗅觉交流的基本理解的空白。该项目将用于培训本科生和研究生以及来自代表性不足群体的高中生，使其掌握行为分析和实验的现代方法。将制作一个关于嗅觉辨别的教育游戏，可以整合到高中生的课堂课程中。理解气味辨别的机制仍然是动物行为的感觉生理学中的一个挑战性问题，包括受体水平和高级大脑中心对嗅觉信息的处理。该项目的重点是在受体水平上的气味识别机制，并为此目的使用表皮碳氢化合物的化合物组。表皮碳氢化合物作为长链烃的复杂混合物出现在几乎所有昆虫的体表，并用于许多重要的环境中，包括配偶通信和群体歧视，这需要基于其表皮碳氢化合物概况对个体进行分类。在社会性昆虫中，对非群体成员的歧视对于避免任何形式的群体剥削尤为重要。因此，在社会性昆虫中，对这些辨别能力的强选择是预期的。蚂蚁丰富的嗅觉受体库将被利用，以确定在表皮碳氢化合物的歧视的关键受体。这些烃敏感嗅觉受体的调谐曲线将被确定和比较。这些分析将与生物测定相结合，以确定个别碳氢化合物的区别。表皮烃敏感嗅觉受体在蚂蚁的受体发育中的丰富性，以及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。通过对嗅觉受体的配体特异性进行功能分析，并结合受体分子的三维重建，将确定分子序列的变化如何导致嗅觉空间的扩大。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值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.