BRC-BIO: Determining the neural mechanisms regulating photostimulation of migratory physiology and behavior

这个项目将使我们了解鸣禽的大脑如何利用环境信息来确定季节性迁徙的时间。与留鸟不同，候鸟特别容易受到环境变化的影响，因为它们每年必须在多种环境中迁徙。它们必须在不直接了解目的地环境条件的情况下确定迁徙行程的时间，依靠普遍的季节线索，特别是白天长度和光周期的季节变化，来适当地选择出发时间。然而，我们仍然对大脑中将光周期信息处理成支持迁移所必需的生理和行为的复杂变化的途径知之甚少。特别是，迁徙和繁殖准备都依赖于相同的季节光周期线索，这限制了我们理解迁徙时间是如何控制的能力。该项目将使用先前确定的光照制度来分离迁徙生理和繁殖，以确定特定于迁徙的神经机制。通过了解动物如何利用光周期线索来确定迁徙时间，我们将能够更好地预测候鸟能够灵活应对的环境变化范围，为保护工作提供信息。本计划将为多名本科生提供资助研究机会，减轻学生在研究与有薪工作之间的选择，从而扩大有能力参与本科生研究的人数。基于该项目开发的设备和资源，将开发一系列关于候鸟生理和行为的公共宣传资源，用于当地和整个阿拉巴马湾沿岸社区的活动。该项目由BRC BIO计划和促进竞争研究的既定计划（EPSCoR）共同资助。该项目解决了鸣禽如何探测和整合来自其环境的光信号到生理、形态和行为的复杂变化中以支持春季迁徙的基本问题。光周期的变化被认为是控制许多物种迁移时间的预测线索。然而，迁移时间的潜在机制仍然模糊不清。这是因为季节性迁徙和繁殖都依赖于增加的春季光周期作为线索，并且需要大脑内的甲状腺激素信号发生。这种迁移和生殖机制之间的重叠限制了旨在确定神经机制的观察性研究的效用，以及简单的操作努力（如甲状腺敲除）的功效。该项目利用先前建立的低强度绿光范式来光刺激春季迁徙的发展，而不触发白冠麻雀系统的生殖生理。然后，该项目将通过开发用于免疫组织化学的定制抗体来定位能够检测这种低强度绿光线索的深部脑光感受器的神经表达。然后通过多靶点原位杂交分析，确定甲状腺神经激素信号的迁移特异性变化。最后，我们将通过AAV2病毒载体介导的shRNAi敲低脑内视蛋白表达，然后使用绿光模式刺激迁移，来测试可能的光受体候选物在调节迁移生理中的直接作用。这项工作将为迁移时间的神经机制和潜在可塑性提供新的见解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will allow us to understand how the brains of songbirds use environmental information to time seasonal migrations. Unlike resident species, migratory birds are particularly susceptible to environmental change as they must move through multiple environments each year. They must time migratory journeys without direct knowledge of environmental conditions at their destination, relying on generalized seasonal cues, specifically the seasonal change in day length, photoperiod, to appropriately time departure. However, we still know very little about the pathways in the brain that process photoperiod information into the complex changes in physiology and behavior necessary to support migration. In particular, the shared reliance of both migration and preparation for reproduction on the same seasonal photoperiod cues has limited our ability to understand how migratory timing is controlled. This project will use previously identified lighting regimes to isolate migratory physiology from reproduction in order to identify those neural mechanisms specific to migration. By understanding how animals use photoperiod cues to time migration we will be better able to predict the scope of environmental change to which migratory birds can flexibly respond, informing conservation efforts. This project will create funded research opportunities for multiple undergraduate students to broaden the population of students able to participate in undergraduate research by alleviating the choice between research and a paying job. Building on the equipment and resources developed by this project, a series of public outreach resources on migratory bird physiology and behavior will be developed for use at events both locally and throughout the Alabama Gulf Coast community. The project was jointly funded by the BRC BIO program and the Established Program to Stimulate Competitive Research (EPSCoR).This project addresses the fundamental questions of how songbirds detect and integrate photic cues from their environment into the complex array of changes in physiology, morphology, and behavior necessary to support spring migration. Photoperiod changes are well established as a predictive cue controlling migratory timing for many species. However, the mechanisms underlying timing of migration remain obscured. This is because both seasonal migration and reproduction both rely on increasing spring photoperiod as a cue and require thyroid hormone signaling within the brain to occur. This overlap between migratory and reproductive mechanisms has limited the utility of observational studies that aim to identify neural mechanisms, as well as the efficacy of simple manipulative efforts such as thyroid knockouts. This project leverages a previously established low intensity green light paradigm to photostimulate the development of vernal migration without triggering reproductive physiology in the well-studied white-crowned sparrow system. The project will then localize neural expression of deep brain photoreceptors capable of detecting this low intensity green light cue by developing custom antibodies for immunohistochemistry. Then through multi-target in situ hybridization analysis, it will identify migration specific changes in neural thyroid hormones signaling. Finally, the direct role of putative photoreceptor candidates in regulating migratory physiology will be tested by AAV2 viral vector-mediated shRNAi knockdown of opsin expression in the brain followed by stimulation of migration using the green light paradigm. This work will provide novel insight into the neural mechanisms and the potential plasticity of migratory timing.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.