A NEW MECHANISM FOR MODULATING COLOUR VISION: OPSIN EXPRESSION
Christiana Cheng and Inigo Flamarique from the Fraser University Department of Biological Sciences (Burnaby, British Columbia V5A 1S6, Canada email@example.com) studied photoreceptor plasticity in the Pacific pink salmon, Oncorhynchus gorbuscha, (Opsin expression: New mechanism for modulating colour vision. Nature 428, 279 18 March 2004) demonstrating that single cones start making a different opsin as young salmon move to deeper waters. Each cone photoreceptor in the retina responds to light in a limited range of wavelengths, giving it a spectral phenotype. This phenotype is determined by the most prevalent of the photoreceptor's visual-pigment proteins (opsins) and is assumed to remain unchanged during an animal's lifetime. The authors show that in the pink salmon single cones can switch their spectral phenotype from ultraviolet to blue by regulating the production of the appropriate opsins as the fish grow older. This photoreceptor plasticity may operate to modulate colour vision as the salmon's lifestyle changes.