Single Gene Disease        Complex Disorders       Evolutionary Genetics    

Evolutionary Genetics

The study of the evolution of the visual system in vertebrates addresses the origin of the different classes of photoreceptors and visual pigments present in different species. On the basis of amino acid sequence identity, visual pigments fall into a single rod and four cone classes. Where all four pigments are present, as in some fish and birds, tetrachromatic colour vision is conferred. Two of the cone classes that specify pigments with peak sensitivities in the middle part of the visual spectrum have been lost in mammals, with the result that most mammals are dichromats. Old world primates have regained trichromacy by a duplication of the Long Wave Sensitive gene. Ongoing work is focused on the mechanisms of spectral tuning of pigments (for example, the shift in the short wave-sensitive class from peak sensitivity in the UV to the violet region of the spectrum) and on the role of tuning and gene duplication in the adaptation of the visual system to differing light environments.

IoO researchers working in this area:

Professor Jim Bowmaker
Professor David Hunt
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