STUDIES OF THE FORCE SENSITIVITY OF INDIVIDUAL SWIMMING PROTISTS USING MAGNETIC FORCE BUOYANCY VARIATION

在本提案中，PI将研究单细胞生物的代表：草履虫的力传感机制。草履虫在向上游动时要比向下游动时施加更大的推进力来对抗沉积的倾向。这种行为表明草履虫可以感知压力差对应的力，压力差小于大气压的1/ 1000000。为了研究这种敏感力响应的未知来源，PI将对草履虫施加力，并测量其游泳轨迹的几何形状和速度如何变化。它们的轨迹特征将揭示它们的力感机制。这些方法将利用位于佛罗里达州塔拉哈西的国家高磁场实验室产生的强磁场。磁场也将被用来引导和控制游动的草履虫，这样它们就可以长时间地研究单个游泳者。除了细胞力传感领域的工作人员外，对细胞运动，特别是低雷诺数游泳感兴趣的科学家社区也会对这些结果感兴趣。提议的实验将作为布朗大学博士生的博士论文工作。它将使学生接触到实验研究的各个方面，包括实验设计、数据采集和分析以及结果传播。学生将发展生物物理学的专业知识，包括细胞的机械转导和细胞运动，这将增加我们国家的科学和技术基础。

In this proposal the PI will study the force sensing mechanism in a representative of the unicellular organisms: paramecia. Paramecium fights its tendency to sediment exerting a stronger propulsive force when it swims upward than when it swims downward. This behavior indicates that paramecia can sense forces corresponding to pressure differences that are less than 1/10,000,000th of atmospheric pressure. To investigate the unknown source of this sensitive force response the PI will apply forces on paramecia and measuring how the geometry and speed of their swimming trajectories change. The characteristics of their trajectories will reveal their force sensing mechanisms. The methods will employ the intense magnetic fields generated at the National High Magnetic Field Laboratory in Tallahassee, Florida. Magnetic fields will also be used to direct and contain the swimming paramecia so that they can study individual swimmers for extended periods of time. In addition to workers in the cell force sensing field, the results will be of interest to the community of scientists interested in cell motility and in particular, low Reynolds number swimming. The proposed experiments will serve as the PhD thesis work for a PhD student at Brown University. It will expose the student to all aspects of experimental research including experimental design, data acquisition and analysis, and results dissemination. The student will develop expertise in biophysics including mechano-transduction in cells and cell motility and this training will augment our nations science and technology base.