Joel Kralj
Assistant Professor
Molecular Cellular and Developmental Biology • BioFrontiers Institute

Kralj Lab
3415 Colorado Ave
JSC Biotech; UCB 596
Boulder, CO 80303

Dr. Kralj is an Assistant Professor in the BioFrontiers Institute and the department of Molecular Cellular and Developmental Biology.  Dr. Kralj received his undergraduate degree in engineering physics from Santa Clara University, followed by a PhD in physics at Boston University in 2009.  From there, he joined the lab of Adam Cohen at Harvard University for his postdoctoral research.  Dr. Kralj started his own lab at CU-Boulder in 2014.  The Kralj lab is focused on developing new tools to optically measure cellular physiology and applying those tools to study biology at previously inaccessible scales.  Current projects include imaging electrical activity in 3D neuronal cultures, high throughput genetic screens of voltage physiology, and uncovering the role of transient electrical activity in bacteria.

Selected Publications:

  1. Dodd, BJT, Kralj, Joel M. “Live cell imaging reveals pH oscillations in Saccharomyces cerevisiae during metabolic transitions.” Scientific Reports, (2017)
  2. Bruni, GN., Weekley, RA., Dodd, BJ., Kralj, Joel M.  “Voltage induced calcium flux mediates mechanosensation in Escherichia coli.”  PNAS, 114,35 (2017).
  3. Dempsey GT, Chaudhary KW, Atwater N, Nguyen C, Brown BS, McNeish JD, Cohen AE, Kralj, Joel M. “Cardiotoxicity screening with simultaneous optogenetic pacing, voltage imaging, and calcium imaging.” Journal of Pharmacological and Toxicological Methods, (2016)
  4. Hochbaum, DR., Zhao, Y., Farhi, SL., Klapoetke, N., Werley, CA., Kapoor, V., Zou, P., Kralj, Joel M., Maclaurin, D., Smedemark-Margulies, N., Saulnier, JL., Boulting, GL., Sraub, C., Cho, YK., Melkonian, M., Wong, GK., Harrison, DJ., Murthy, VN., Sabatini, BL., Boyden, ES., Campbell, RE., Cohen, AE.  “All-optical Electrophysiology in Mammalian Neurons Using Engineered Microbial Rhodopsins.” Nature Methods (2014)
  5. Kralj, Joel M*., Douglass, AD*., Hochbaum, DR*., Cohen, AE. “Optical Recording of Action Potentials in Mammalian Neurons with a Voltage Indicating Protein.” Nature Methods, 9(1):90-95. (2012)
  6. Kralj, Joel M., Hochbaum, DR., Douglass AD., Cohen AE. “Electrical Spiking in Escherichia Coli Probed with a Fluorescent Voltage Indicating Protein.” Science, 333(6040):345-348 (2011)