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

这项拟议的项目旨在了解磁接收在生物系统中的作用。磁感应是候鸟在全球范围内导航时使用的一种生物学感觉。已经有人提出，初级探测器是一种特殊的眼睛光感受器，它主持以自由基对为转瞬即逝中间体的磁敏光化学反应。自由基对是一种短暂的反应中间体，包括两个串联形成的自由基(自由基是具有未成对的价电子或开放电子壳层的原子、分子或离子)，其未成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--产物产量或反应速率随磁场强度的变化而变化。悬而未决的问题是，这种机制是否是鸟类磁感应的基础。这项拟议工作的目标是开发一种方法来测量磁场对光感受器分子中发生的化学反应的影响。PI与Osher终身学习研究所(Olli)合作，Osher终身学习研究所(Olli)是一个为高级学习者提供量子力学和量子生物学课程的学习社区。Olli每年提供150门课程和40项额外活动，可供近2600名会员使用。Co-Pi将在西部地区教育服务联盟的STEM创业计划中介绍磁性和化学传感，这是一个一年两次的活动，来自北卡罗来纳州西部八个县18个学校系统的小学、初中和高中生参加。这些活动向不同年龄和背景的公众传播研究成果，目的是提高科学素养和参与当地社区。该项目的长期目标是提供证据，证明鸟类的磁感应是一种量子现象。为了起到定向传感器的作用，隐色素蛋白(隐色素的化学成分，一种在鸟类视网膜中发现的蓝光感光蛋白，被推测负责磁感应)必须定向。对于在隐铬中形成的自由基对作为磁感受器，它们必须表现出对外部磁场的敏感性，包括那些像50-100μT的地球自然场一样弱的磁场，而且这种敏感性必须与方向有关。此外，体外研究表明，增加粘度会导致磁敏感度的增加。脂膜结合是实现这两个要求的一种很有前途的方法。这项拟议工作的主要目标是开发一种消逝波腔增强型光谱仪来测量磁场对膜结合分子之间发生的化学反应的影响。中心假设是，膜缔合将自由基对磁传感器转变为能够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--包括隐色素--的影响。从生态学的角度出发，了解鸟类的航行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，它的运行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方案。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。

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.