Provencio I et al. (1998), Melanopsin: An opsin in melanophores, brain, an...

XB-ART-15423

Proc Natl Acad Sci U S A 1998 Jan 06;951:340-5. doi: 10.1073/pnas.95.1.340.

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Melanopsin: An opsin in melanophores, brain, and eye.

Provencio I , Jiang G , De Grip WJ , Hayes WP , Rollag MD .

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We have identified an opsin, melanopsin, in photosensitive dermal melanophores of Xenopus laevis. Its deduced amino acid sequence shares greatest homology with cephalopod opsins. The predicted secondary structure of melanopsin indicates the presence of a long cytoplasmic tail with multiple putative phosphorylation sites, suggesting that this opsin's function may be finely regulated. Melanopsin mRNA is expressed in hypothalamic sites thought to contain deep brain photoreceptors and in the iris, a structure known to be directly photosensitive in amphibians. Melanopsin message is also localized in retinal cells residing in the outermost lamina of the inner nuclear layer where horizontal cells are typically found. Its expression in retinal and nonretinal tissues suggests a role in vision and nonvisual photoreceptive tasks, such as photic control of skin pigmentation, pupillary aperture, and circadian and photoperiodic physiology.

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Species referenced: Xenopus laevis
Genes referenced: opn1lw opn1sw opn4 opn4xb rho rpe sri
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	Figure 1 Western blot of protein extracts from dermal melanophores and whole eye probed with an antiserum raised against bovine rhodopsin. Indicated molecular masses are in kDa. Lanes: 1, total protein from cultured melanophores; 2, 1% of total protein from a whole early postmetamorphic adult eye. A 50-kDa immunoreactive band is present in both lanes (solid arrowhead). The 35- and 70-kDa bands in lane 2 are monomeric and dimeric rhodopsin, respectively (open arrowheads).
	Figure 4 Bright-field and dark-field photomicrographs of melanopsin transcript distribution within extraocular structures. Melanopsin message was localized to tadpole (stages 56 and 57) dermal melanophores (A and B), the ventral aspect of the magnocellular preoptic nucleus (Mgv) (D and E), and the SCN (G and H) of the tadpole brain (stages 56 and 57). Cell-specific antisense hybridization was restricted to a subset of SCN cells (I). In contrast, incubation with the sense control probe yielded no hybridization above background (C and F). (Corresponding bright-field views are not shown.) OC, optic chiasm. [Bars = 20 Î¼m (A), 150 Î¼m (D), 75 Î¼m (G), and 15 Î¼m (I).]
	Figure 5 Bright-field and dark-field photomicrographs of melanopsin transcript distribution within ocular structures. In sections of tadpole (stages 56 and 57) (A and B) and adult (D and E) eye, melanopsin transcripts were identified in retinal cells within the outer lamina of the inner nuclear layer (INL) (A, B, D, and E). In contrast, incubation of adjacent sections with the sense RNA probe (C and F) resulted in no labeling above background. (Corresponding bright-field views are not shown.) Intense cell-specific hybridization was also observed in the iris and less intensely within the RPE. GC, ganglion cell layer; ONL, outer nuclear layer; OS, photoreceptor outer segments. [Bars = 150 Î¼m (A) and 35 Î¼m (D).]
	loc100485437 (opsin 4 (melanopsin)[predicted]) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 56, transverse sections of eye. Note that labeling in the lens is non-specific

References [+] :

Altschul, Basic local alignment search tool. 1990, Pubmed