Talk:Melanopsin

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BBC article[edit]

[1] Article may be helpful for wikipedians who are more comfortable with the topic. (Unsigned comment added 30 January 2005 by user:Wk muriithi) (Heading for comment added in July 2009. --Hordaland (talk) 18:20, 12 July 2009 (UTC))[reply]

Expansion suggested[edit]

This article would be almost incomprehensible to most Wikipedia users. It needs a general introductory paragraph in lay language, perhaps focussing on the discovery of melanopsin as a third human photoreceptor, and its role and adaptive usefulness. I think it belongs in several other categories, too, eg something to do with "vision" or "light detection". yoyo 16:47, 19 October 2006 (UTC)[reply]

Human-specific among mammals[edit]

Nothing in the article indicates the surprising fact that among mammals, melanopsin appears to be unique to humans; although it has been found in several other vertebrates, including frogs and fish. Perhaps it is worth mentioning. The fact poses the interesting questions:

How do other primates trigger the pupillary reflex? and
Supposing the mechanism used by other primates to be efficient, why did humans need to evolve a new one?

yoyo 17:04, 19 October 2006 (UTC)[reply]

--Melanopsin is emphatically not unique to humans. The majority of the current research on melanopsin is being performed in mice, and mice definitely express melanopsin. I've seen the stained slides. (Unsigned comment by user:Stevewylie, 12 November 2006)

Notes concerning section "Discovery and function"[edit]

Removal of paragraph regarding melanopsin absorption peak @ 420nm[edit]

The paragraph:

“It has been proposed that melanopsin could be the photopigment contained in intrinsically photosensitive Retinal Ganglion Cells (ipRGC), which are the cells assumed to mediate the melatonin suppression in human. However, the measured melanopsin absorption peak (~420nm)^[1] does not match well with the peak sensitivity reported for melatonin suppression in human (~440-480 nm).^[2]”

points to a 2003 paper reporting a measured absorption peak at ~420nm, thus raising the question of the discrepancy with the measured peak sensitivity for melatonin suppression in human at ~440-480nm. The reference^[3] that I added next to the mentioned 480nm absorption peak of melanopsin (paragraph just above the cited paragraph), specifically addresses this issue (see p.851 of the paper) by explaining that the 420nm absorption peak observed in the early attempts to determine the absorption spectrum of melanopsin, was an artefact of the buffer used in the extraction process of the melanopsin. Since that time, other melanopsin extraction processes have been developed and the resulting melanopsin exhibits an absorption peak at ~480nm, which is within the range of the observed action spectrum for melatonin suppression in human. Thus the proposed removal of the cited paragraph from the article. Lessato (talk) 17:42, 25 April 2009 (UTC)[reply]

Moving ref list here from bottom of page. --Hordaland (talk) 21:17, 10 April 2015 (UTC)[reply]

^ Newman LA, Walker MT, Brown RL, Cronin TW, Robinson PR (2003). "Melanopsin forms a functional short-wavelength photopigment". Biochemistry. 42 (44): 12734–8. doi:10.1021/bi035418z. PMID 14596587. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
^ Brainard GC, Hanifin JP, Greeson JM, Byrne B, Glickman G, Gerner E, Rollag MD (2001). "Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor". J. Neurosci. 21 (16): 6405–12. PMID 11487664. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
^ Berson, M. (Aug 2007). "Phototransduction in ganglion-cell photoreceptors". Pflugers Archiv : European journal of physiology. 454 (5): 849–855. doi:10.1007/s00424-007-0242-2. ISSN 0031-6768. PMID 17351786.

Removed paragraph[edit]

I've removed the following paragraph. There is no source given at all. It would also be pertinent to explain what species this gene therapy was done on. The paragraph should be replaced and expanded, iff reliable source(s) are found.

In October 2008, Massachusetts General Hospital researchers used melanopsin as the delivered gene in a four-week process of gene therapy. Ultimately, melanopsin, normally produced in one percent of retinal ganglion cells, was expressed in ten percent of the lines in the treated eyes but not in those given a sham injection.^{[clarification needed]}^{[citation needed]}

- Hordaland (talk) 18:14, 12 July 2009 (UTC)[reply]

SCN[edit]

What is SCN? "In 2002, Samer Hattar and his colleagues provided evidence supporting prior theories that melanopsin is the photopigment responsible for mammalian SCN entrainment." --217.253.218.197 (talk) 10:28, 6 May 2012 (UTC)[reply]

Thanks for asking!! It's now fixed. The SCN is the director of the body clocks, or is the primary body clock, in mammals. Short for suprachiasmatic nuclei or nucleus. It's a tiny double bundle of a few thousand nerve cells, sitting right above the crossing point of the optic nerves. --Hordaland (talk) 12:29, 6 May 2012 (UTC)[reply]

Old studies[edit]

This article describes the details of various studies. That sort of thing is fine for scientific questions that have not yet been resolved. However, once the scientific community arrives at a consensus on something, it should be enough to just state the consensus position as a fact, and leave out the details. Otherwise the reader is overburdened with "too much information."

Just as an example, before human melanopsin was discovered, 460 nm was identified as the optimal wavelength for melatonin suppression and pupil constriction in humans. This led to the hypothesis that the human retina must have another opsin. When human melanopsin was found, they noticed that the peak sensitivity was higher than expected. This led scholars to consider either experimental error, or the possibility that melanopsin might have a much broader sensitivity range than other opsins. Eventually the issue was resolved with the discovery that the Giant retinal ganglion cells mediates melatonin suppression and pupil constriction, that they have a peak sensitivity of 460 nm, that they not only carry melanopsin, but also receive inputs from rods and all three kinds of cones (through various interneurons). Some of the information in this article dates from the time when this issue was unresolved. Zyxwv99 (talk) 22:43, 1 November 2015 (UTC)[reply]

Moving stray URL[edit]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5020820/

This URL was recently added to the very bottom of the article page. Moving it here, as it may be useful. It is an August 2016 study entitled "Melanopsin expression is an indicator of the well-being of melanopsin-expressing retinal ganglion cells but not of their viability".

--Hordaland (talk) 16:18, 27 December 2016 (UTC)[reply]

PMID 27930778[edit]

User:Casper123, PMID 27930778 is what we call a primary source and we don't use them to support content about health. Please see WP:MEDDEF which is part of WP:MEDRS. I gave you a note about MEDRS here. Jytdog (talk) 16:03, 9 January 2017 (UTC)[reply]

[pmid14596587-1] Newman LA, Walker MT, Brown RL, Cronin TW, Robinson PR (2003). "Melanopsin forms a functional short-wavelength photopigment". Biochemistry. 42 (44): 12734–8. doi:10.1021/bi035418z. PMID 14596587. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)

[pmid11487664-2] Brainard GC, Hanifin JP, Greeson JM, Byrne B, Glickman G, Gerner E, Rollag MD (2001). "Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor". J. Neurosci. 21 (16): 6405–12. PMID 11487664. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)

[3] Berson, M. (Aug 2007). "Phototransduction in ganglion-cell photoreceptors". Pflugers Archiv : European journal of physiology. 454 (5): 849–855. doi:10.1007/s00424-007-0242-2. ISSN 0031-6768. PMID 17351786.

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