Neuronal and molecular basis for magnetic transduction in the nematode C. elegans

这项研究将调查利用地球磁场导航的动物是如何将这种力场转化为有意义的神经信号和行为的。地球的磁场有水平和垂直两个分量，虽然许多动物已知使用磁场的水平分量(例如鲑鱼)或垂直分量(例如海龟)，但人们对它们如何检测和转换这些信息知之甚少。确定动物如何探测和处理磁场信息将解开感觉神经科学的现代谜团之一。它还将通过阐明生命系统如何与自然和人造磁场相互作用来提高我们对动物行为的理解。更具体地说，这项研究将通过识别允许蠕虫探测并定向到磁力场的分子，来确定线虫体内磁性颗粒的亚细胞位置和性质。此外，它还将阐明神经系统如何处理磁性信息。该项目将支持对高中生、本科生和研究生的培训，以及正在进行的提高高危儿童科学素养的外联工作。具体来说，高中生将通过正在进行的暑期科学“新兵训练营”计划和招募当地高中生到实验室做志愿者来接受培训。他们将学习如何生成假设，进行实验来测试它们，分析和交流他们的发现。几名研究生和本科生将有机会直接参与该项目，从而获得完整的科学研究经验。参加两门生物技术实验室课程的研究生和本科生也将受益于在正在进行的科学研究背景下学习现代分子技术。所有参与的学生都将学习基本的科学素养，目标是在会议上发表摘要，并根据他们的研究共同撰写科学出版物。行为的产生依赖于个体感觉系统、整合系统和运动系统之间的相互作用。虽然人们对大多数感官模式的传导都知道很多，但动物如何探测和定位地球磁场仍然是感官神经科学的最后前沿之一。最近，首席研究人员发现了处理磁信息的神经元，确定了磁感觉的候选机制，更重要的是，在任何动物中发现了第一个磁敏神经元。该项目将通过用荧光标记的候选细胞纯化动物体内的磁性颗粒，或通过免疫组织化学标记它们，来确定磁性颗粒在线虫组织中的细胞定位。这些颗粒的大小和组成将通过透射电子显微镜和扫描电子显微镜-能谱分析来确定。原子力显微镜将被用来测量它们的磁矩和亚细胞定位。为了确定哪些蛋白质负责在磁敏神经元附近组装磁性颗粒，将使用RNA干扰来沉默与铁相关的基因表达。然后将评估这些动物的趋磁反应，并通过免疫组织化学评估磁性颗粒的定位。候选蛋白将使用聚合酶链式反应-融合技术进行标记。之前对线虫组织中分离出的磁性颗粒进行的质谱分析表明，它们富含机械感受器Pezo-1和其他动物中参与触摸传导的几种蛋白质。RNA干扰将被用来沉默参与磁传导的候选蛋白质，并使用钙指示剂GCaMP6记录磁敏神经元中由此产生的磁反应的变化。充分性将通过细胞特异性的、开放阅读框架介导的候选基因的挽救来测试。这些蛋白质的亚细胞定位将通过聚合酶链式反应融合荧光标记来完成。为了确定线虫如何编码磁场，GCaMP6将在感觉神经元和下游神经元中表达。暴露在不同方向和幅度的磁场中的动物的神经元反应将被记录下来。该项目的完成将揭示磁性颗粒是如何组装的，并有助于线虫对磁场的检测。磁转换机制的解决，以及磁场编码的神经元基础，可能会揭示利用地球磁场产生适应行为的保守分子和细胞策略。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。

This research will investigate how animals that use the earth's magnetic field for navigation and transform this force field into meaningful nervous signals and behavior. The magnetic field of the earth has horizontal and vertical components and while many animals are known to use either the horizontal (e.g. salmon), or the vertical component of the field (e.g. sea turtles), how they detect and translate this information is poorly understood. Determining how animals detect and process magnetic field information will solve one of the modern mysteries of sensory neuroscience. It will also improve our understanding of animal behavior by clarifying how living systems interact with natural and artificial magnetic fields. More specifically, this research will determine the subcellular location and nature of magnetic particles in the nematode C. elegans by identifying the molecules that allow worms to detect and orient to magnetic force fields. Further, it will elucidate how the nervous system processes magnetic information. The project will support the training of high school, undergraduate, and graduate students, as well as ongoing outreach efforts to increase science literacy among at risk children. Specifically, high school students will be trained through an ongoing summer science "boot camp" program and by recruiting local high school students to volunteer in the lab. They will learn how to generate hypotheses, perform experiments to test them, analyze and communicate their findings. Several graduate and undergraduate students will be given the opportunity to participate directly in the project, thereby gaining a complete scientific research experience. Graduate and undergraduate students enrolled in two biotechnology laboratory courses will also benefit by learning modern molecular techniques in the context of ongoing scientific research. All participating students will learn basic scientific literacy with the goal of presenting abstracts at meetings and co-authoring scientific publications based upon their research. The production of a behavior relies on the interaction between the sensory, integrating, and motor systems in an individual. While much is known about the transduction of most sensory modalities, how animals detect and orient to the earth's magnetic field remains one of the final frontiers of sensory neuroscience. Recently, the principal investigator identified neurons that process magnetic information, identifying candidate mechanisms for magnetic sensation, and, importantly, the first magnetosensitive neurons in any animal. This project will determine the cellular localization of magnetic particles in the tissues of C. elegans by purifying these particles in animals with fluorescently labelled candidate cells, or labelling them immunohistochemically. The size and composition of these particles will be determined using TEM and SEM-EDX analysis. Atomic force microscopy will be used to measure their magnetic moment and subcellular localization. To determine which proteins are responsible for assembling magnetic particles near the magnetosensory neurons, RNA interference will be used to silence iron-related gene expression. The magnetotactic response of these animals will then be evaluated, and the localization of magnetic particles evaluated through immunohistochemistry. Candidate proteins will be tagged using PCR-fusion. Previous mass spectrometry analysis of magnetic particles isolated from the tissues of C. elegans revealed them enriched for the mechanoreceptor PEZO-1 and several proteins involved in touch transduction in other animals. RNA interference will be used to silence candidate proteins involved in magnetic transduction and record the resulting changes in magnetic responses in the magnetosensory neurons using the calcium indicator GCaMP6. Sufficiency will be tested by means of cell-specific, ORF-mediated, rescue of candidate genes. Subcellular localization of these proteins will be accomplished through PCR-fusion to fluorescently tag them. To identify how C. elegans encodes magnetic fields, GCaMP6 will be expressed in sensory and downstream neurons. Neuronal responses will be recorded in animals exposed to magnetic fields of varying directions and amplitudes. Completion of this project will reveal how magnetic particles are assembled and contribute to the detection of magnetic fields by C. elegans. The resolution of the magnetic transduction machinery, and the neuronal basis of magnetic field coding will likely reveal conserved molecular and cellular strategies for harnessing the earth's magnetic field in the production of adaptive behavior.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.