I subsequently chose to focus in biochemistry in graduate school with the goal of understanding how cells function at the molecular level. After obtaining my Ph.D. in biochemistry, I developed an interest in vision research and directed my research efforts toward identifying proteins of rod and cone photoreceptor cells that function in the visual process and are involved in various forms of retinitis pigmentosa and related retinal degenerative diseases. Rod and cone photoreceptor cells are specialized neurons of the vertebrate retina which function in the detection of light, the transduction of light into electrical signals, and the transmission of these electrical signals to secondary neurons of the retina as part of the visual process. Rod cells are highly sensitive to light, function primarily under dim lighting conditions, and are important in peripheral vision. Cone cells are less sensitive to light and function under normal and bright lighting conditions.
Cone cells are also responsible for colour vision.
Both the rod and cone photoreceptor cells contain a specialized subcellular compartment called the outer segment which serves as the site for phototransduction, that is, the process by which light is converted into an electrical response. Although structurally similar, there are differences between the rod outer segments and cone outer segments. In order to understand the molecular basis for photoreceptor degenerative diseases, laboratories including mine are researching the molecular properties, structure and function of rod and cone outer segment proteins. The absence of normal proteins or presence of defective proteins generally results in the abnormal development or slow deterioration of photoreceptor cells leading to the loss in vision. Over the past several years, scientists have identified many mutations in genes that code for a variety of photoreceptor cell specific proteins.