Cohen, Adam EzraHou, Jennifer2014-02-252014-02-252013Hou, Jennifer Hsin-I. 2014. Dynamics in Biological Soft Materials. Doctoral dissertation, Harvard University.http://dissertations.umi.com/gsas.harvard:11269http://nrs.harvard.edu/urn-3:HUL.InstRepos:11744434I present applications of imaging and spectroscopy to understand mechanical, chemical, and electrical dynamics in biological materials. The first part describes the development and characterization of a protein-based fluorescent calcium and voltage indicator (CaViar). The far-red fluorescence of CaViar faithfully tracks the cardiac action potential in cardiomyocytes. CaViar's green fluorescence reports the resulting calcium transients. I demonstrated the applicability of CaViar in vivo with transgenic zebrafish designed to express CaViar in their hearts. Spinning disk confocal imaging allowed detailed three-dimensional mapping of simultaneous voltage and calcium dynamics throughout the heart of zebrafish embryos, in vivo, as a function of developmental stage. I tested the effect of channel blockers on voltage and calcium dynamics and discovered a chamber-specific transition from a calcium-dependent to a sodium-dependent action potential. I also describe a new measurement technique using a fluorescent voltage indicator to report absolute voltage via the indicator's temporal response.en-USPhysicsBiophysicssoft mattervoltage imagingzebrafish cardiac developmentThesis or Dissertation2015-02-04