Chemistry and Biochemistry

Harvard Professor Adam E. Cohen Opens Rossiter Lecture Series

Posted: Jan 23, 2017

Harvard professor Adam E. Cohen opened the Rossiter Lecture series on January 19-20, 2017. This lecture series was established in tribute to Dr. Bryant E. Rossiter who was a professor at Brigham Young University from 1985-1994. "Professor Bryant Rossiter was a scholar, mentor, exceptionally gifted intellect, father, scientist, and former professor at Brigham Young University. . . His life was tragically and prematurely cut short by cancer.  He was only 41 when he passed away, but his contributions to Chemistry, and the lives of his students make an impact to this day," says former student Dr. Shawn Reese. 

Dr. Cohen works at the "interface of physics, chemistry and biology," according to Harvard Administrative Contact Magdalena Kenar, at Harvard University and is the founder of the Q-State Biosciences Corporation. Cohen graduated summa cum laude from Harvard and holds PhD degrees from Cambridge (United Kingdom) in theoretical physics and from Stanford in experimental biophysics.  Technology Review Magazine named him one of the top 35 US technological innovators under the age of 35 and Popular Science named him one of their “Brilliant Ten” top young scientists.  He has received an NIH New Innovator Award and a Presidential Early Career Award for Scientists and Engineers (PECASE) from President Obama. The Cohen Lab at Harvard develops new physical tools to study molecules and cells.  His Lab also developed fluorescent voltage-indicating proteins which enable optical mapping of neural activity.  These tools have opened the door to all-optical electrophysiology and to large-scale mapping of brain activity. His lab has also studied fundamental aspects of chiral light-matter interactions, predicting theoretically and then demonstrating experimentally the existence of “superchiral” light. 

Cohen's first talk, entitled "Bringing Bioelectricity to Light," focused on the photochemistry of microbial rhodopsins, and some applications to unusual bioelectrical systems."No one has looked at electrophysicology in a lot of things," explains Cohen. "Science, like any sport, thanks their athletes," in this case the athletes being bioelectricity. Every cell is encased in an electrically insulating lipid membrane, bathed in a conducting milieu. The membrane can support an internal electric field, which tugs on charges in the membrane. Membrane voltage modulates the free-energy landscape of all molecules associated with the membrane.  This voltage regulates the activity of neurons, cardiac cells, and many other biological structures.  "A key challenge has been the difficulty of visualizing changes in transmembrane potential. We discovered that a protein derived from a Dead Sea microorganism could function as an exquisitely fast and sensitive fluorescent reporter of membrane voltage.  By engineering the photocycles of microbial rhodopsins, we developed fluorescent voltage indicators which could implement new measurement modalities, such as light-gated voltage integration, and measurements of absolute voltage," says Cohen.

In the second talk, entitled "Studying function in rodent and human neurons," Cohen describes how he has used all-optical electrophysiology to study neural function in primary neurons in vitro, in human iPSC-derived neurons, in acute brain slice, and in live mice. Measurements in intact tissue pose interesting technical challenges associated with kilohertz-rate imaging through a strongly scattering, autofluorescent medium. This groundbreaking research concerning optical electrophysiology in neurons provides insights into diseases such as pain, epilepsy, and ALS, and has the ability to provide much needed help to the many patients around the world who are afflicted with these infirmities. 

 

Writer: Taelin Dedrick

Photo Credit: Marius Bugge