Physics (Internal)

Imaging Voltage: From E. coli to neurons

This event is part of the Biophysics/Condensed Matter Seminar Series.

Abstract:   Biological systems use voltage to transmit information over distance scales from microns to meters.  The only way to accurately measure cellular voltage is through direct electrical contact either with an electrode or patch clamp which are limited by the number of cells one can interface, a single point of measurement, and the destructive nature of the measurements.  We sought to avoid these limitations by developing a genetically encoded, fluorescent sensor of membrane potential.  We generated a family of Voltage Indicating Proteins (VIPs) based on microbial rhodopsins which show up to a three fold increase in fluorescence from -150 to 150 mV and less than 500 ms response time.  In cultured neurons, VIPs resolve individual action potentials on a single trial basis with a SNR of 10.5.  In human iPS derived cardiomyocytes, we can continuously image spontaneous action potentials for 1000 seconds without affecting the intrinsic kinetics.  Additionally, we used a Proteorhodopsin Optical Proton Sensor to see “action potential”-like electrical activity in E. coli for the first time and correlated it to efflux of a small molecule dye.  We believe that VIPs will allow for the first time a robust tool for electrophysiology beyond wires.   PI: Adam Cohen