The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twenty-four-month research fellowship by Dr. Martha E. Sommer to work with Dr. Peter K. Hofmann at the Charite-Universitatsmedizin in Berlin, Germany.
Rod cells of the retina can function as single photon detectors, and yet they are routinely exposed to 1010 times more light. This proposal focuses on understanding the molecular details of how the rod cell both protects itself from bright light as well as returns to an adapted state that can again sense single photons (dark adaptation). The PI's graduate work yielded several intriguing findings that, together with the past work of others, led to a hypothesis that the protein arrestin might protect the rod cell in bright light by trapping retinal in rhodopsin. In addition, arrestin may be necessary for timely dark adaptation by interacting with the late rhodopsin photoproduct Meta III and converting it to a form that can be regenerated. However, direct evidence, especially in the native rod membrane system, is still lacking. Here, she proposes to test these hypotheses with the host. Dr. Hofmann and his group are experts in the biophysical methodologies necessary to identify rhodopsin photoproducts and monitor their interactions with arrestin with meaningful time and structural resolution (Fourier Transform Infrared, light-scattering, absorbance, and fluorescence spectroscopies). In addition, they have extensive expertise in kinetic theory and rate analysis, which is essential to interpret in vitro results in the context of how vision operates in situ.
