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 inigo@sfu.ca) 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.
BM&L-March 2004