I work on light energy transduction by retinal proteins. The two major systems are thus visual pigments with their visual cascade, in which 11-cis retinal is the chromophore, and bacteriorhodopsin, in which all-trans retinal is the chromophore. Vision involves light sensing while photosynthesis involves light energy conversion. Most of the ways of converting light energy into chemical energy are in systems which use chlorophyll to absorb the light. Bacteriorhodopsin does this in a system using a retinal chromophore to absorb the light. Bacteriorhdopsin and its cousins are found in halobacteria, members of the Archaebacteria kingdom, and these species grow only in extremely saline water. We are trying to find out how the absorption of the light by the bacteriorhodopsin leads to the movement of protons across the halobacteria's cell membrane. I have started a collaboration with Rose Ann Cattolico's lab to study the pigments underlying phototaxis in algae.