Vitamin A metabolism in day light vision

What is it about?

Vision requires continuous regeneration of visual pigments in rod and cone photoreceptors. Cones are sensitive in day light where rods are less useful. It is generally assumed that the capacity of the established chromophore regeneration pathway for rods is not sufficient to guarantee chromophore supply of cones under daylight illumination. Our study employs the cone rich eyes of zebrafish to identify a novel biochemical pathway for chromophore regeneration. Pharmacological inhibition and genetic dissection provides evidence that this novel cycle accommodates cone vision in the fish retina. The existence of the same chromophore intermediates in eyes of diurnal mammals suggests evolutionary conservation of this pathway. In fact, the study shows how nature can solve complex biochemical problems by simple modifications of existing pathways for metabolic building blocks.

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Why is it important?

Cone photoreceptors mediate color vision and provide the majority of sensory input in our brain. Inherited and chronic diseases including the age related macular degeneration affect cone vision.

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