PUBLICATION
Zebrafish melanopsin: isolation, tissue localisation and phylogenetic position
- Authors
- Bellingham, J., Whitmore, D., Philp, A.R., Wells, D.J., and Foster, R.G.
- ID
- ZDB-PUB-030115-1
- Date
- 2002
- Source
- Brain research. Molecular brain research 107(2): 128-136 (Journal)
- Registered Authors
- Whitmore, David
- Keywords
- circadian; evolution opsin; photoreception; retina; zebrafish
- MeSH Terms
-
- Animals
- Evolution, Molecular
- Gene Expression/physiology
- Light Signal Transduction/genetics
- Molecular Sequence Data
- Neurons/cytology
- Neurons/metabolism*
- Photoreceptor Cells, Vertebrate/cytology
- Photoreceptor Cells, Vertebrate/metabolism
- Phylogeny
- Protein Structure, Tertiary/genetics
- Retina/cytology
- Retina/metabolism*
- Rod Opsins/genetics
- Rod Opsins/isolation & purification*
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Zebrafish/metabolism*
- Zebrafish Proteins/genetics
- Zebrafish Proteins/isolation & purification*
- PubMed
- 12487121 Full text @ Brain Res. Mol. Brain Res.
Citation
Bellingham, J., Whitmore, D., Philp, A.R., Wells, D.J., and Foster, R.G. (2002) Zebrafish melanopsin: isolation, tissue localisation and phylogenetic position. Brain research. Molecular brain research. 107(2):128-136.
Abstract
Photoreception is best understood in retinal rods and cones, but it is not confined to these cells. In non-mammals, intrinsically photosensitive cells have been identified within several structures including the pineal, hypothalamus and skin. More recently novel light sensitive cells have been identified in the inner/basal retina of both teleosts and rodents. Melanopsin has been proposed as the photopigment mediating many of these non-rod, non-cone responses to light. However, much about the melanopsin gene family remains to be clarified including their potential role as photopigments, and taxonomic distribution. We have isolated the first orthologue of melanopsin from a teleost fish and show expression of this gene in a sub-set of retinal horizontal cells (type B). Zebrafish melanopsin, and orthologues of this gene, differ markedly from the vertebrate photopigment opsins. The putative counterion is not a glutamate but a tyrosine, the putative G-protein binding domain in the third cytoplasmic loop is not conserved, and they show low levels of amino acid identity (approximately 27%) to both the known photopigment opsins and to other members of the melanopsin family. Mouse melanopsin is only 58% identical to Xenopus, and 68% identical to zebrafish. By contrast, the photosensory opsin families show approximately 75% conservation. On the basis of their structure, genomic organisation, discrete evolutionary lineage, and their co-expression with other opsins, the melanopins are not obvious photosensory opsins. They might represent a separate branch of photopigment evolution in the vertebrates or they may have a non-direct photosensory function, perhaps as a photoisomerase, in non-rod, non-cone light detection.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping