Dr. Theodore P. Williams, Professor Emeritus, 1933-2003
Ph.D., Princeton University, 1959.
Research and Professional Interests:
This lab was involved in studies of the interaction of light with the photoreceptor cells of the retina. In particular, two lines of research were undertaken: one in which single, living rod and cone cells were examined and one in which the overall effects of light on the animal were studied. The former made use of a high-tech instrument, a microspectrophotometer (MSP), and the latter involved living rats, raised under various lighting conditions.
In the studies of single cells, Dr. Williams and his students characterized the complex ways in which light is absorbed in the cells. It is clear from these studies that nonuniform patterns of light absorption occur in rods within living eyes. Furthermore, the intracellular patterns of pigment regeneration (restoration of native spectrum) are also nonuniform throughout the cells. Finally, with this MSP, they successfully determined the rate of lateral diffusion of visual pigments in several photoreceptor types, including red-sensitive cones. Until these measurements there had been no report of the diffusion coefficient for visual pigment in cone cells.
In the experiments with rats born and raised at various intensities of light, they found that all rats, regardless of the intensity at which they reside, absorb the same number of photons each day. This pattern is made possible by retinal modifications that up- or down-regulate the visual pigment content of the eyes; high-intensity habitats result in low visual pigment content of the eyes and low-intensity habitats the opposite. Dr. Williams dubbed this phenomenon "photostasis," and studied it and the implications it holds for neurohormonal well-being of the rats.
Williams, T. P., and B. N. Baker, eds. 1980. The Effects of Constant Light on Visual Processes. Plenum Press, New York. 455 pp.
Gupta, B. D., and T. P. Williams. 1990. Lateral diffusion of visual pigments in toad (Bufo marinus) rods and in catfish (Ictalurus punctatus) cones. Journal of Physiology 430: 483-496.
Makino, C. L., L. N. Howard, and T. P. Williams. 1990. Dynamic rhodopsin distributions in single toad rods during light-adaptation. Journal of General Physiology 96: 1199-1220.
Williams, T. P., C. L. Makino, and L. N. Howard. 1990. Biophysics and molecular biology of photoreceptors. Dynamic rhodopsin distribution in single toad rods during light-adaptation. Journal of General Physiology 96: 1199-1220.
Bush, R. A., and T. P. Williams. The effect of unilateral optic nerve section on retinal light damage in rats," Experimental Eye Research 52: 139-153.
Williams, T. P., and J.-L. Schremse. 1992. Photoreceptor plasticity in the albino rat retina following unilateral optic nerve section. Experimental Eye Research 55: 393-399.
Remé, C. E., U. Wolfrum, C. Imsand, F. Hafezi, and T. P. Williams. 1999. Photoreceptor autophagy: effects of light history on number and opsin content of degradative vacuoles. Invest. Ophthalmol. Visual Sci. 40:2398–2404.
Williams, T. P., A. Squitieri, R. P. Henderson, and J. P. P. Webbers. 1999. Reciprocity between light intensity and rhodopsin concentration across the rat retina. J. Physiol. (London) 516:869–874.
Grimm, C., C. E. Remé, P. O. Rol, and T. P. Williams. 2000. Blue light's effects on rhodopsin: photoreversal of bleaching in living rat eyes. Invest. Ophthalmol. Visual Sci. 41:3984–3990.
Williams, T. P., and A. B. Thistle, eds. 1998. Photostasis and Related Phenomena. Plenum Press, New York. 225 pp.Wenzel, A., C. E. Remé, T. P. Williams, F. Hafezi, and C. Grimm. 2001. The Rpe65 Leu450Met variation increases retinal resistance against light-induced degeneration by slowing rhodopsin regeneration. J. Neurosci. 21:53–58.