Vision in animals is triggered via absorption of a photon by a visual pigment complex located in the photosensory cells of the eye. Activation of a visual pigment forms the first step in a biochemical cascade of events that eventually leads to a neural signal indicating that light has been perceived. Changes in the biochemical properties of visual pigments can therefore have profound consequences on the visual capabilities of an organism.

Research in our laboratory focuses on studying visual pigment function by reconstructing the evolutionary history of these proteins, so that important changes in their function can be examined experimentally. This involves using bioinformatic tools such as phylogenetic ancestral reconstruction methods to infer ancestral pigment sequences, followed by synthesis and expression of the ancestral genes in the laboratory so that their biochemical properties can be assayed directly instead of merely extrapolating from present day sequences. This can tell us something not only about biology of the ancient organisms in which these ancestral proteins occurred, but also the evolutionary history of the key changes in structure and function in this protein family. The visual system has a surprisingly large dynamic range, and is highly specialized for the efficient sensing of light even under very low light levels. How is this extremely sensitive photosensing achieved at the molecular level?

We are also interested in the molecular evolution of color vision. The basis of color vision is derived from visual pigments that absorb maximally light of many different wavelengths, ranging from the ultraviolet to the red. How is this range achieved in a single family of proteins with rather similar structures? Our research addresses these questions using a variety of methods in addition to recreating ancestral proteins, including comparative sequence analysis, site-directed mutagenesis and protein expression, and the characterization of visual pigments of animals that have interesting visual behaviours, or live in unusual visual environments.