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BioFrontiers Seminar Series: Dr. Joel Kralj from the Department of Chemistry, Harvard University
Start Date: 1/24/2013Start Time: 1:30 PM
End Date: 1/24/2013End Time: 2:30 PM
Event Description:
Dr. Kralj will be visiting campus January 24-25, 2013. He will give a talk Thursday, January 24, 2013 at 1:30P in the JILA Auditorium. The title of his talk is “Imaging voltage in electrically excitable cells”.

Voltage is used in biology to communicate information over length scales from microns to meters. Historically, voltage is measured using electrodes or patch clamp, both of which require mechanical contact and are limited to a small number of point measurements. To facilitate electrophysiological measurements, we developed a genetically encoded, fluorescent sensor of membrane potential based on the photoactive family of proteins, microbial rhodopsins. These Voltage Indicating Proteins (VIPs) modulate their fluorescence intensity in response to the membrane potential across a cell. We used VIPs to resolve individual action potentials on a single trial basis of rat hippocampal neurons and human iPS derived cardiomyocytes with high signal to noise ratio. Further, they allow spatially and temporally resolved voltage maps without cellular damage. VIPs enable electrophysiological measurements on systems inaccessible to patch clamp including bacteria. We recorded voltage from individual bacteria for the first time, and revealed action potential-like voltage spiking that was correlated to efflux of a small molecule dye.

More recently, we have leveraged the far red emission of VIPs by fusing spectrally orthogonal fluorescent indicators of calcium, pH, or ATP. These new sensors allow simultaneous imaging of multiple biological signals at the single cell level. We have also expressed VIPs in tandem with optogenetic actuators such as channel rhodopsin to create an all optical platform for electrophysiology without wires. We are working to generalize VIPs to more relevant sample preps such as tissue slice and in vivo, as well as developing instruments capable of high-throughput electrophysiology.

Go to for more information about Dr. Krajl’s research.
Contact Information:
Name: Emilia Costales
Phone: (303) 735-3001
BioFrontiers Seminar Series
This event is open to
  • Everyone
  • Of note:
    Reception will Follow!

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