Hurley, James

The goal of the Hurley group is to develop a molecular understanding of how photoreceptors survive and function in the vertebrate retina. When a retina is dark-adapted an increase in illumination of only a few photons per second can be detected and reported to the brain. When a retina is light adapted it can report changes in illumination on a backgrounds of billions of photons per second. How can a tissue respond with such extreme sensitivity under one condition and avoid saturation under intense stimulation under other conditions? Within the retina there are two types of photoreceptors, rods and cones. Rods are specialized for extraordinary sensitivity; they can detect single photons Cones are specialized for adaptation. Responses of cones do not saturate even under conditions of extremely intense illumination.

Previously Dr. Hurley and his colleagues focused their efforts on identifying and characterizing proteins in rods and cones that are required for transduction of light into an electrical change in rods and cones. These proteins include rhodopsin, transducin, cGMP phosphodiesterase and guanylyl cyclase. More recently, the group has focused on other enzymes that modulate the phototransduction mechanism, including GCAPs, recoverin and rhodopsin kinase. Measurements of biochemical activities and understanding of regulatory mechanisms have been the focus of those studies.

Most recently, the focus of the group has broadened to pursue an understanding of neuronal energy metabolism. The viability and function of neurons rely on proper control of metabolic energy. Our primary aim now is to understand how metabolic energy is produced and distributed in photoreceptors. We are investigating the molecular mechansisms by which these neurons respond to the changing temporal and spatial energy demands of darkness and light.