Award details

Evolution of photopic and scotopic vision in vertebrates

Reference	BB/D521630/1
Principal Investigator / Supervisor	Professor David Hunt
Co-Investigators / Co-Supervisors	Professor James Bowmaker
Institution	University College London
Department	Institute of Ophthalmology
Funding type	Research
Value (£)	217,568
Status	Completed
Type	Research Grant
Start date	01/10/2005
End date	30/09/2008
Duration	36 months

Abstract

In vertebrates, the high sensitivity of rod photoreceptors to light provides vision in dim light (scotopic vision) whereas cone photoreceptors are less sensitive and allow vision in daylight (photopic vision). They are also responsible for colour vision. The differences in sensitivity between these two systems is attributable to differences in the molecular and biochemical machinery of phototransduction in cones and rod photoreceptors. In evolutionary terms, photopic vision almost certainly preceded scotopic vision and our recent evidence that only cone visual pigments are found in the lamprey indicates that this occurred after the separation of the jawed and jawless vertebrates around 540 million years ago. The objective of this project is to establish whether differences in the component processes of phototransduction are present in the different photoreceptors of the lamprey. The work will focus on the regeneration and formation of visual pigment intermediates, on the kinases, arrestins, and cGMP-gated channel proteins where cone- and rod-specific isoforms are known to occur in higher vertebrates, and on retinal guanylyl cyclases and the activating proteins where the different isoforms are found in both rods and cones.

Summary

Vertebrate vision is generally dependent on two types of light-sensitive cells in the retina of the eye, the so-called rod and cone photoreceptors. Rod photoreceptors remain sensitive in dim light (scotopic vision) whereas cones are responsible for normal daylight vision (photopic vision) and for colour vision. These two types of photoreceptor have different sensitivities to light and it is the evolution of these differences that has enabled vertebrates to see in different light environments. In evolutionary terms, photopic vision almost certainly preceded scotopic vision and there is good evidence that this occurred after the separation of the jawed and jawless vertebrates around 540 million years ago. The different light sensitivities of scotopic and photopic vision is achieved by molecular and biochemical differences in the photoreceptors. The objective of this project is to establish whether such differences are present in a representative of the ancestral jawless vertebrates, the lampreys.

Committee	Closed Committee - Animal Sciences (AS)
Research Topics	Neuroscience and Behaviour
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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