PhDAustralian National University, 1982
Dr. Payne investigates mechanisms of visual excitation in photoreceptors. The research concentrates on messenger molecules released by light inside photoreceptor cells. These messengers mediate and modulate the electrical response of the photoreceptor to light. One messenger under investigation is inositol trisphosphate, which releases calcium from internal stores within a wide range of animal and plant cells. When injected into the giant photoreceptors of the horseshoe crab, inositol trisphosphate mimics excitation of the cell by light. Biochemical studies have shown that light releases inositol trisphosphate from the photoreceptor's membrane into the cell interior. These giant photoreceptors are one of the few living cells in which the actions of this important messenger can be easily studied.