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

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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.