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Shozo YokoyamaAsa G. Candler Professor Emeritus


  • Ph.D. University of Edinburgh (2005)
  • M.Sc. Wageningen University (2001)

Research Area

  • Genetics, Cell, and Developmental Biology
  • Population Biology, Evolution, and Ecology

Graduate Program Affiliation

  • Genetics and Molecular Biology

Research Description

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.

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.

Research Lab Description

We study the molecular genetics and adaptive evolution of color and dim-light vision in various vertebrate species. To elucidate the molecular mechanisms of these adaptive events, we use methods of molecular/cell biology, protein modeling, quantum chemistry, psychophysics, and molecular evolution.