title: Vision in the ultraviolet.
abstract: Sensitivity to ultraviolet light (UV) is achieved by photoreceptors in the eye that contain a class of visual pigments maximally sensitive to light at wavelengths <400 nm. It is widespread in the animal kingdom where it is used for mate choice, communication and foraging for food. UV sensitivity is not, however, a constant feature of the visual system, and in many vertebrate species, the UV-sensitive (UVS) pigment is replaced by a violet-sensitive (VS) pigment with maximal sensitivity between 410 and 435 nm. The role of protonation of the Schiff base-chromophore linkage and the mechanism for tuning of pigments into the UV is discussed in detail. Amino acid sequence analysis of vertebrate VS/UVS pigments indicates that the ancestral pigment was UVS, with loss of UV sensitivity occurring separately in mammals, amphibia and birds, and subsequently regained by a single amino acid substitution in certain bird species. In contrast, no loss of UV sensitivity has occurred in the UVS pigments of insects.
authors.affiliation: Institute of Ophthalmology, University College London, United Kingdom. d.hunt@ucl.ac.uk
authors.forename: D M
authors.initials: DM
authors.lastname: Hunt
authors.forename: S E
authors.initials: SE
authors.lastname: Wilkie
authors.forename: J K
authors.initials: JK
authors.lastname: Bowmaker
authors.forename: S
authors.initials: S
authors.lastname: Poopalasundaram
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D008958:Models, Molecular; D015394:Molecular Structure; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D012160:Retina / Q000166:cytology / Q000378:metabolism; D012168:Retinal Pigments / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D017299:Rod Opsins / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D014466:Ultraviolet Rays; D014785:Vision, Ocular / Q000502:physiology*
chemical_list: D012168:Retinal Pigments; D017299:Rod Opsins