Advanced Imaging Techniques for Studying Membrane Mechanics

OHCs are cellular, micro-electromechanical systems, capable of amplifying the vibration of fluid within the cochlea prior to transduction by the inner hair cells.  They are vital for proper discrimination of unique auditory frequencies.  The shape of OHCs has been shown experimentally to change in response to electrical stimuli through either an elongation or shortening.  Little is known about how this shape change is accommodated or directed by the plasma membrane.  Until recently, fluorescent techniques did not achieve the axial resolution necessary to effectively study the membrane, however new techniques such as total internal reflection fluorescence (TIRF) and fluorescence polarization microscopy (FPM) are making this possible.  TIRF is ideal for imaging both membrane curvature and membrane protein location and dynamics.  Its shallow excitation depths ensure minimal background fluorescence and it accomplishes far superior axial resolution than its fluorescence predecessors.  FPM has long been known as an effective tool for studying molecular orientations and preliminary studies have shown that the OHC membrane is suitable for this type of microscopy.  The combination of these two imaging techniques with a mathematical modeling approach will produce unique findings regarding OHC membrane mechanics.