Collaborative Research: Discrimination of Complex Mixtures in Olfactory Signaling

对于居住在地球上的大多数动物来说，嗅觉是生存的关键。气味被用来寻找食物、庇护所和配偶，也被用来标记领土。性信息素是包括昆虫在内的许多动物用来确定配偶位置的信号，几乎在所有情况下都是化学物质的混合物。挥发性化合物的准确混合、比例和浓度为同一物种的个体之间提供了精确的沟通。事实上，大多数气味是混合的，因此了解它们是如何被神经系统检测和处理的，对于总体上研究嗅觉是基本感兴趣的。许多昆虫在幼虫和成虫阶段表现出明显的体型差异。成虫的触角(昆虫的鼻子)是在变态过程中由一块被称为触角想象盘的组织形成的。类似的椎间盘在变态过程中会产生其他成人特有的结构，如翅膀、腿、眼睛和生殖器。这个项目中使用的三种相关蛾都在性信息素中使用了不同的混合物。每种雄鸟的触角上都有一组不同的感觉神经元，用来探测雌鸟释放的独特信息素混合物中的挥发物。在变态过程中，触角形象盘产生了所有的感觉神经元，这些神经元将填充成人的触角。来自这些神经元的过程称为轴突，它们生长到发育中的大脑中，在那里它们与其他中枢神经元相互作用，产生触角叶。这种结构类似于人类的嗅球，它是最初处理嗅觉信息的地方。因为触角形象盘是一个离散的组织块，它可以从即将进入变态阶段的毛虫中取出，然后移植到不同物种的宿主毛虫身上。在变态后，个别接受了移植天线的雄蛾可以在风洞中飞行，以确定它们喜欢的气味混合物。随后，既可以从单个毛发上记录触角上的嗅觉神经元，也可以从触角叶上填充的中央嗅觉神经元进行记录。行为学和神经生理学方法的结合将为控制大脑中神经元之间连接的机制提供普遍适用的见解，以及这对飞蛾和其他动物处理和区分不同气味混合物的能力有多具体的贡献。康奈尔大学和犹他大学的研究人员之间的合作将包括继续培训各种人员，从高中生到本科生和来访的科学家，他们将从接触到一个综合的、合作的研究项目中受益。这些实验的结果将被纳入课堂教学和一般公众宣传活动。

For most of the animals that inhabit our planet the sense of smell is critical for survival. Odors are used to find food, shelter, and mates, as well as to mark territories. Sex pheromones are signals used by many animals, including insects, for the purpose of mate location, and are in almost all cases mixtures of chemicals. The exact blend, ratio and concentration of volatile compounds provides for precise communication between individuals of the same species. Indeed, most smells are mixtures and thus understanding how they are detected and processed by the nervous system is of fundamental interest to research on olfaction in general. Many insects exhibit distinct differences in body form between juvenile and adult stages. The adult antenna (the insect 'nose') is formed during metamorphosis from a patch of tissue known as the antennal imaginal disc. Similar discs give rise to other adult-specific structures such as wings, legs, eyes and genitalia during metamorphosis. The three related moth species that will be used in this project all utilize different mixtures in their sex pheromones. Males of each species have a different set of sensory neurons on the antenna that detect the volatiles present in the unique pheromone mixture released by their females. During metamorphosis the antennal imaginal disc gives rise to all the sensory neurons that will populate the adult antenna. Processes from these neurons called axons grow into the developing brain where they interact with other central neurons to produce the antennal lobe. This structure is comparable to the human olfactory bulb and it is the site where initial processing of olfactory information occurs. Because the antennal imaginal disc is a discrete patch of tissue it can be removed from a caterpillar that is about to enter into the metamorphic stage and transplanted into a host caterpillar of a different species. After metamorphosis, individual male moths that have received a transplanted antenna can be flown in a wind tunnel to determine the odor mixtures that they prefer. Subsequently recordings can be made both from individual hairs that house olfactory sensory neurons on the antenna and central olfactory neurons that populate the antennal lobe. The combination of behavioral and neurophysiological approaches will provide generally applicable insights into the mechanisms that control the wiring of connections between neurons in the brain and how specifically this contributes to the ability of moths and other animals to process and discriminate amongst different odor mixtures. The partnership between investigators at Cornell University and the University of Utah will involve the continued training of a variety of personnel from high school students to undergraduates and visiting scientists who will benefit from exposure to an integrative, collaborative research program. Results from these experiments will be incorporated into classroom teaching and general public outreach activities.