Department of Biology
Biology Faculty Profile
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Shozo Yokoyama, Emeritus
Asa G. Candler Professor
Office Phone: 404-727-5379 | Lab Phone: 404-727-5378
Office Room: Rollins 2101
Office Address: Emory University, Department of Biology, O. Wayne Rollins Research Center, 1510 Clifton Road NE, Atlanta , GA 30322
Lab Room: Rollins 1154/1158
Lab Website

Research Area:
Genetics, Cell, and Developmental Biology
Population Biology, Evolution, and Ecology

Graduate Program Affiliation:
Genetics and Molecular Biology


B.S. (Plant Breeding), Miyazaki University, Miyazaki, Japan, 1968
M.S. (Plant Breeding), Kyushu University, Fukuoka, Japan, 1971
Ph.D. (Biomathematics), University of Washington, Seattle, WA, 1977

The molecular basis of spectral tuning in photosensitive molecules, visual pigments, is a central unanswered question in phototransduction. It is also extremely difficult to study the molecular mechanisms of phenotypic adaptations. In order to solve these questions simultaneously, our lab studies the molecular genetics and evolution of color and dim-light vision in vertebrates.

Using recombinant DNA techniques, we clone opsin genes from a wide range of vertebrate species. The opsin cDNAs are expressed in cultured cells, reconstituted with 11-cis-retinal, and the absorption spectra of the resulting visual pigments are determined. Based on the amino acid sequences of the contemporary visual pigments, we infer those of various ancestral pigments and actually engineer them. Using site-directed mutagenesis, we identify critical amino acid substitutions that modified the absorption spectra during vertebrate evolution. To elucidate the role of chemical interactions on the spectral tuning in these visual pigments, we also model chemical structures and conduct quantum chemical analyses of the ancestral and contemporary pigments.

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