SGER: Characterization of the Magnetic Compass in C57 BL/6 Mice

磁罗盘的特征是C57BL/6 MiceJohn B.Phillips生物部弗吉尼亚理工大学布莱克斯堡，弗吉尼亚州24061-0406项目摘要。这项拟议的研究将使用实验室小鼠的行为方法来研究负责探测地球磁场的感觉机制。C57BL/6品系的实验室小鼠将被用来研究一类新发现的感光色素是否是小鼠磁罗盘的重要组成部分，这些感光色素参与将昼夜节律与明暗周期同步(隐色素)，这些感光色素也与磁场感应有关。还将进行实验，以确定低水平的宽带(1-20兆赫)无线电频场是否会干扰磁罗盘的定向(如最近对鸟类和两栖动物的研究所显示的那样)。对于显示会影响鸟类磁罗经方向的给定频率(7 MHz)，将确定在鼠标系统中影响磁罗经方向的强度阈值。这项工作的潜在影响包括：(1)表征小型哺乳动物的磁场敏感性的机制；(2)表征在新的感觉系统(磁罗盘)从特征明确的先兆(依赖光的生物钟)进化过程中发生的分子变化；(3)开发用于操纵获取磁信息的生物物理和遗传技术，这些技术可用于研究磁刺激在其他行为和神经生理反应中的作用；(4)与美国和国外的一些实验室开发合作研究计划，目标是：a)使用离散的无线电频率来表征磁罗盘背后的生物物理过程，b)对光敏生物钟的变化进行建模，这对于优化对光输入的微小的磁场依赖的调制是必要的，以及c)确定参与处理磁信息的大脑区域。

Characterization of the Magnetic Compass is C57 BL/6 MiceJohn B. PhillipsBiology DepartmentVirginia TechBlacksburg, VA 24061-0406Project Summary. The proposed research will use a behavioral approach with laboratory mice to investigate the sensory mechanism responsible for detection of the Earth's magnetic field. The C57 BL/6 strain of laboratory mouse will be used to investigate whether a newly-discovered class of photopigments involved in synchronizing circadian rhythms to the light-dark cycle (cryptochromes), which have also been implicated in magnetic field sensing, are an essential component of the mouse's magnetic compass. Experiments will also be carried out to determine whether low-level, broad band (1-20 MHz) radio frequency fields disrupt magnetic compass orientation (as shown in recent studies of birds and amphibians). For a given frequency (7 MHz) shown to affect magnetic compass orientation of birds, the intensity threshold for an effect on magnetic compass orientation in the mouse system will be determined. The potential impact of this work includes: (1) characterization of the mechanism responsible for magnetic field sensitivity in a small mammal; (2) characterization of the molecular changes that have occurred during the evolution of a novel sensory system (the magnetic compass) from a well-characterized antecedent (the light-dependent circadian clock); (3) development of biophysical and genetic techniques for manipulating access to magnetic information that can be used to investigate the role of magnetic stimuli in other behavioral and neurophysiological responses; (4) development of collaborative research programs with a number of laboratories in the USA and abroad with the goals of: a) using discrete radio frequencies to characterize the biophysical processes underlying the magnetic compass, b) modeling the changes in a light-sensitive circadian clock that would be necessary to optimize sensitivity to small, magnetic-field-dependent modulations of light input, and c) identifying brain regions involved in the processing of magnetic information.