EAGER: Illuminating the consequences of membrane association on quantum-based magnetosensing

拟议的项目旨在了解磁感受在生物系统中的作用。磁感是候鸟在全球范围内导航的一种生物感觉。有人提出，初级探测器是一种特殊的眼光感受器，它在具有自由基对作为短暂中间体的磁敏感光化学反应中起宿主作用。自由基对是由两个自由基（自由基是具有未配对价电子或开放电子壳层的原子、分子或离子）组成的短寿命反应中间体，其未配对的电子自旋可以是反平行的（单重态）或平行的（三重态）。未配对自旋的量子相互作用可以产生磁场效应——产物产率或反应速率的差异作为磁场强度的函数。悬而未决的问题是，这种机制是否是鸟类磁感受的基础。提出的工作的目的是开发方法来测量磁场对发生在光感受器分子中的化学反应的影响。PI与Osher终身学习研究所（OLLI）合作，这是一个面向高级学习者的学习社区，提供量子力学和量子生物学课程。OLLI每年为近2600名会员提供150门课程和40项额外活动。共同负责人将在西部地区教育服务联盟（Western Region Education Service Alliance）的STEM创业项目上介绍磁性和化学传感，该项目每两年举办一次，吸引来自北卡罗来纳州西部8个县18个学校系统的小学、初中和高中学生。这些活动导致向不同年龄和背景的公众传播研究成果，其目标是提高当地社区的科学素养和参与。该项目的长期目标是提供证据，证明鸟类的磁感受是一种量子现象。作为一个方向传感器，隐花色素蛋白（隐花色素的化学性质，在鸟类视网膜中发现的一种蓝光感光蛋白，据推测是负责磁感）必须是定向的。对于在隐花色素中形成的自由基对作为磁感受器，它们必须表现出对外部场的敏感性，包括像地球自然场50-100 μT那样弱的磁场，并且这种敏感性必须具有方向依赖性。此外，体外研究表明，粘度的增加会导致磁敏感性的增加。脂膜结合是一种很有前途的方法来实现这两个要求。提出的工作的主要目的是开发一种倏逝波腔增强光谱仪，以测量磁场对膜结合分子之间发生的化学反应的影响。核心假设是，膜结合将一个自由基对磁传感器转变为一个可以感知地球强度场的分子罗盘。如果成功，该项目将允许该领域展示各向异性磁场对生物分子的影响，包括隐花色素。从生态学角度出发，了解鸟类导航机制对保护候鸟具有重要意义。除此之外，如果这种现象的量子起源被证明是正确的，那么它的运作原理可以为导航设备的设计提供信息，作为基于卫星的全球定位系统的替代品。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。

The proposed project is aiming to understand the roles of magnetoreception in the biological systems. Magnetoreception is a biological sense employed by migratory birds to navigate on a global scale. It has been proposed that the primary detector is a specialized ocular photoreceptor that plays host to magnetically sensitive photochemical reactions having radical pairs as fleeting intermediates. A radical pair is a short-lived reaction intermediate comprising two radicals (radical is an atom, molecule, or ion that has unpaired valence electrons or an open electron shell) formed in tandem whose unpaired electron spins may be either antiparallel (a singlet state) or parallel (a triplet state). Quantum interaction of unpaired spins can generate Magnetic Field Effects – a difference in product yield or reaction rate as a function of the field strength. The open question is whether this mechanism is the foundation of avian magnetoreception. The objective of the proposed work is to develop methodology to measure magnetic field effects on chemical reactions occurring in the photoreceptor molecules. The PI is partnered with the Osher Lifelong Learning Institute (OLLI), a learning community for senior learners, to offer classes on quantum mechanics and quantum biology. OLLI offers 150 courses and 40 additional events per year that are available to nearly 2600 members. The Co-PI will present on magnetism and chemical sensing at the Western Region Education Service Alliance’s STEM Entrepreneurship program, a biannual event that engages elementary, middle, and high school students from 18 school systems across eight counties in western North Carolina. These activities lead to dissemination of research results to the public across a wide range of ages and backgrounds, with the goal of increasing scientific literacy and engagement in the local community.The long-term goal of this project is to provide evidence that avian magnetoreception is a quantum phenomenon. To act as a directional sensor, Cryptochrome proteins (chemistry of Cryptochrome, a blue-light photoreceptor protein found in the avian retina, are speculated to be responsible for magnetic sensing) must be oriented. For radical pairs formed in Cryptochrome to act as a magnetoreceptor, they must demonstrate sensitivity to external fields, including those as weak as the Earth’s natural field of 50-100 μT, and that sensitivity must have a direction dependence. Furthermore, in vitro studies suggest that increasing viscosity leads to an increase in magnetic sensitivity. Lipid membrane association is a promising way to achieve both requirements. The main objective of the proposed work is to develop an evanescent-wave cavity enhanced spectrometer to measure magnetic field effects on chemical reactions occurring between membrane-bound molecules. The central hypothesis is that membrane association transforms a radical pair magnetosensor into a molecular compass that can sense Earth strength fields. If successful, the project will allow the field to demonstrate anisotropic magnetic field effects on biomolecules – including Cryptochrome. From an ecological perspective, understanding the mechanism of avian navigation is important to protect migratory birds. Beyond that, if the quantum origin of this phenomenon proves correct, the principles of its operation can inform the design of navigational devices as alternatives to satellite-based global positioning systems.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.