
	Where results make sense

Topic: Melanopsin

Related Topics

Transducin

Suprachiasmatic nucleus

Spinal cord

Ichthyostega

	Melanopsin at AllExperts
		Melanopsin is a photopigment found in specialized ganglion cells of the retina that are involved in the regulation of circadian rhythms and pupillary reflex.
		In structure, melanopsin is an opsin, a variety of G-protein-coupled receptor.
		Melanopsin ganglion cells are thought to influence these targets by releasing from their axon terminals the neurotransmitters glutamate and pituitary adenylate cyclase activating polypeptide (PACAP).
	en.allexperts.com /e/m/me/melanopsin.htm (445 words)

	Melanopsin - Wikipedia, the free encyclopedia
		Melanopsin is a photopigment found in specialized photosensitive ganglion cells of the retina that are involved in the regulation of circadian rhythms and pupillary reflex.
		In structure, melanopsin is an opsin, a variety of G-protein-coupled receptor.
		Induction of photosensitivity by heterologous expression of melanopsin
	en.wikipedia.org /wiki/Melanopsin (574 words)

	melanopsin ( circadian stuff)
		The protein is called 'melanopsin' and it seems to be present in parts of the retina -- the light-sensitive double lining of the back of the eyeball -- that are known to connect to the body's primary, so-called 'circadian' pacemaker.
		Melanopsin had been found before in several vertebrates such as frogs and fish, but this research, reported in the Journal of Neuroscience1, is the first time that it has been detected in mammals.
		Second, unlike other opsins, human melanopsin does not seem to be made in the light-sensitive 'photoreceptor' cells of the outer layer of the retina; rather it seems to be made (just as it is in frogs and fish) by cells in the inner layer.
	www.sleepnet.com /narco5/messages/806.html (502 words)

	CiteULike: Impaired masking responses to light in melanopsin-knockout mice. (Site not responding. Last check: 2007-10-20)
		To investigate the role of the newly discovered opsin-like protein melanopsin in masking, we used 1 h and 3 h pulses of light given in the night, and also a 3.5:3.5 h light-dark (LD) cycle.
		Mice lacking the melanopsin gene had normal enhancement of locomotion in the presence of dim lights but an impaired suppression of locomotion in the presence of bright light.
		This suggests that melanopsin in retinal ganglion cells is involved in masking, as it is in pupil contraction and phase shifts.
	www.citeulike.org /user/morven/article/773604 (461 words)

	The Scientist : What Sets the Biological Clock?
		Melanopsin Captured: A rat retinal ganglion cell containing Melanopsin (green) located in the membrane of both soma and dendrites and PACAP (red), a neurotransmitter of the retinohypothalamic tract.
		In the few cells the antibodies recognized, melanopsin was found at the cell's surface and "everywhere in the cell—the cell body, all the processes, and including even the part of the axon on the retina, [but] disappears as it goes to the brain," Yau notes.
		Melanopsin is found on the surface of the RGCs that innervate areas of the brain involved in regulating circadian rhythm, pupillary response, melatonin release, and other light-dependent phenomena.
	www.the-scientist.com /article/display/13096 (1678 words)

	Current Biology -- Sekaran et al. (Site not responding. Last check: 2007-10-20)
		Intrinsic light responses of ganglion-cell-layer neurons were absent in neonatal melanopsin knockout mice, confirming that melanopsin expression is a prerequisite for inner-retinal photosensitivity and also consistent with recent studies that confirm that melanopsin expression alone is sufficient to engender photoresponsiveness [[17, 18, 19]].
		Importantly, in melanopsin knockout mice, Fos induction was not detectable in the early neonate (Figure 6A and 6B) even though normal axonal projections of melanopsin-expressing retinal ganglion cells to the SCN were observed (Figure 7A and 7B).
		Melanopsin associates with cis-isoforms of retinal, but recent evidence suggests that it may have the capability to function as a bistable pigment and to regenerate its chromophore from all-trans isomers [[17, 18]].
	www.current-biology.com /content/article/fulltext?uid=PIIS0960982205005683&refuid=PIIS0896627305009645 (6598 words)

	Scientists shed new light on the body's internal clock: 12/02
		According to the researchers, melanopsin may be one of several photosensitive receptors that work redundantly to regulate the circadian system.
		The molecule later was found in frog and mouse retinas, and complementary studies determined that cells containing melanopsin send signals to different parts of the brain -- further evidence of the molecule's potential role in setting the circadian clock.
		"Melanopsin is one of the key players, but it is not the only player," Ruby and O'Hara explained, noting that the knockout mice, which lacked melanopsin, continued to respond to new light patterns, albeit less efficiently.
	www.stanford.edu /dept/news/pr/02/clock18.html (764 words)

	Oscar - Rhythm and blues â“ and jet lag, too
		Melanopsin subsequently was found in some retinal ganglion cells, a mass of neuron cell bodies that transmit visual image information to the brain.
		Of these, only about 2,000 contain melanopsin and are anatomically inconspicuous as photoreceptors, unlike the 110 to 125 million rod and 6.4 million cone cells, whose shapes are distinctive.
		Furthermore, they found that mice lacking melanopsin as well as their rods and cones were “completely insensitive to light by every measure,” he adds.
	oscar.virginia.edu /x6259.xml (838 words)

	Circadiana: ClockNews #17: Melanopsin
		confirming that melanopsin is the photopigment for ganglion-cell photoreceptors.
		On one side is the Melanopsin "mafia", led by Foster, Provencio and Berson.
		Their strategy is to show that melanopsin is the only photopigment involved in circadian photoentrainment and completely ignore the existence of other pigments.
	circadiana.blogspot.com /2005/01/clocknews-17-melanopsin.html (1086 words)

	Single Cell Type Seems To Control Internal Clock and Pupil of Eye
		Melanopsin is suspected to be light-sensitive but not involved in forming visual images.
		The antibody flags melanopsin in cells, while tau-lacZ lights up the tentacle-like axons of nerve cells in which the melanopsin gene is turned on.
		Much remains unknown about melanopsin itself, including whether it is sensitive to light, and about these cells' roles in controlling the clock and pupil, the researchers stress.
	www.hopkinsmedicine.org /press/2002/FEBRUARY/020221.htm (782 words)

	Sensory transduction: Seeing the light - Cell Signaling Update - Signaling Gateway
		Melanopsin — a pigment that is found in the type of retinal ganglion cell that allows light to entrain the circadian clock — can also function as a photopigment in other types of cell.
		Three studies have shown that melanopsin — a pigment that is found in the type of retinal ganglion cell that allows light to entrain the circadian clock — can function as a photopigment in other types of cell.
		Although these contain melanopsin, and lose their photoreceptive properties if melanopsin is removed, it has not previously been shown that melanopsin itself is the photopigment in these cells.
	www.signaling-gateway.org /update/updates/200504/nrn1638.html (518 words)

	2004 Sixth Annual Symposium - Shieh Abstract (Site not responding. Last check: 2007-10-20)
		Melanopsin is an unusual opsin-like protein expressed in a subset of retinal ganglion cells (RGCs).
		Melanopsin is believed to be the elusive photopigment that is involved in regulating circadian rhythms and photoentrainment.
		However, melanopsin absorbs at a wavelength of 420 nm in vitro, and the photopigment mediating the electrical response in the subset of RGCs absorbs at 479 nm.
	www.beckman-foundation.com /04bsp/shieh.html (324 words)

	Researchers link melanopsin gene to unexplored light detection system within the eye
		Melanopsin is an opsin-like protein which is expressed in a small number of ganglion cells in the retina of the eye.
		The research team tested whether melanopsin is part of the new light detecting system by measuring light-induced pupillary constriction in genetically modified mice that lacked melanopsin.
		When the mice lacking melanopsin were exposed to low light, their pupillary response was the same as normal mice, but when they were exposed to bright light their pupil constriction was incomplete.
	www.eurekalert.org /pub_releases/2003-01/icos-rlm010803.php (525 words)

	NWO - MELANOPSIN: CHARACTERIZATION OF A NOVEL PHOTOSENSITIVE SIGNALOSOME
		The original hypothesis that in mammals non-visual photo-responses are mediated also by the visual photoreceptors in the outer retina (rods and cones), was shown incorrect by studies on retinodegenerate mouse models, that clearly indicated the presence of an additional photoreceptor system in the inner neural retina.
		A series of elegant studies on transgenic mice led to the current view that all three photoreceptor systems (rod, cone and subclass of ganglion cells) contribute to non-visual photophysiology, and that melanopsin is in particular required for the response at lower light intensities and for sustained activity.
		Amplified expression in insect cells or a mammalian cell line will be used to produce and purify recombinant melanopsin in sufficient quantities to allow biochemical and biophysical studies on structural and photochemical properties, mechanism of photo-activation as well as G protein selectivity.
	www.nwo.nl /projecten.nsf/pages/2300129185 (442 words)

	NIH News Release--Mouse Gene Knockout Illuminates How Light Resets Clock--12/16/2002
		This suggested that melanopsin is not involved in the normal functioning of the clock itself.
		Then, the researchers exposed the melanopsin knockout mice to 15 minutes of blue light at a time in their cycle when normal mice show strong phase delays — alterations in the time of onset of activity in response to light.
		The researchers propose that melanopsin is required for normal setting of the brain's clock by light, but that other mechanisms for light input also play a role, since the animals still show some phase shifting.
	www.nih.gov /news/pr/dec2002/nimh-16.htm (827 words)

	Oscar - Rhythm and blues â“ and jet lag, too
		Melanopsin subsequently was found in some retinal ganglion cells, a mass of neuron cell bodies that transmit visual image information to the brain.
		Provencio compared mice with melanopsin to “knock-out” mice, which were genetically altered to have no melanopsin.
		Furthermore, they found that mice lacking melanopsin as well as their rods and cones were “completely insensitive to light by every measure,” he adds.
	www.oscar.virginia.edu /x6259.xml (838 words)

	Why We Get SAD (Site not responding. Last check: 2007-10-20)
		Melanopsin is a light sensitive cell that lies in the retina of the eye.
		The melanopsin cells are 'responsible for telling our bodies that it is daytime – daylight is always bright light,' according to Dr Rob Lucas at the Imperial College in London.
		But by increasing full spectrum enough to stimulate the melanopsin photoreceptors, we may also be over stimulating the rod and cone cells and eye muscles, which result in headaches, eyestrain, excessive glare, nausea, etc. Although BLUEWAVE® is bright, it is only 1/25th as bright as full spectrum light, and is much easier on the eyes.
	www.apollohealth.com /newsletter/mar05/page3.html (662 words)

	The Scientist : Melanopsin Lights the Way
		Scientists have since created melanopsin knockout mice and developed other tools to further define the role that RGCs play in a variety of nonimage-forming visual systems and their relationships to the image-forming system.
		Using this and antibodies against melanopsin, they demonstrated that melanopsin is present in the cell bodies, dendrites, and proximal parts of RGC axons that end up in the SCN and other brain nuclei involved with circadian rhythm and the pupillary light reflex.
		Clearly the nonimage-forming pathway is wholly dependent neither on melanopsin nor on rods and cones.
	www.the-scientist.com /2004/4/26/32/1 (1463 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		This criterion is based upon the fact that the inner retina is not juxtaposed to a known chromophore-regenerating tissue such as the retinal pigment epithelium.
		Melanopsin shares greater sequence homology with the opsins of invertebrates than those of vertebrates.
		Finally, the anatomical distribution of melanopsin-positive retinal cells is similar to the pattern of cells known to project from the murine retina to the suprachiasmatic nuclei of the hypothalamus, a primary circadian pacemaker.
	www.pol-us.net /ASP_Home/Meetings/Annual2000/Monday/view_abstract227.html (323 words)

	The Hindu : Controlling internal clock and pupil of eye
		For their experiments, the researchers created a line of mice with one normal copy of the melanopsin gene and one copy that coded for a protein called tau-lacZ instead.
		With these tools, the scientists figured out exactly which cells contained melanopsin, whether those cells were naturally sensitive to light, and where they connected in the brain.
		Much remains unknown about melanopsin, including whether it is sensitive to light, and about these cells' roles in controlling the clock and pupil, the researchers stress.
	www.hindu.com /thehindu/seta/2002/03/07/stories/2002030700220400.htm (489 words)

	ScienceWeek
		Melanopsin has also been localized in the eye of the mouse, monkey, and human and, more precisely, in the ganglion cell layer of the mouse and monkey (5).
		The melanopsin messenger RNA has also been found in the PACAP (pituitary adenylate cyclase-activating polypeptide)-containing RGCs that were previously shown to project to the SCN, indicating that PACAP might be used as a transmitter or modulator in this pathway.
		By cloning rat melanopsin and generating specific antibodies, the authors demonstrate that melanopsin is present in cell bodies, dendrites, and proximal axonal segments of a subset of rat RGCs.
	scienceweek.com /2004/sc040409-2.htm (1432 words)

	Circadian Rhythm Disorders: Melanopsin and Pupil Size
		It turns out that melanopsin has everything to do with body clock problems, and those people who don't have enough melanopsin cells are much more likely to have SAD, sleep problems and mood disorders.
		Now researchers know that melanopsin responds to changing levels of light, and when it gets brighter in the morning for example, melanopsin becomes very active and triggers the brain's suprachiasmatic nucleus, or body clock into shifting to an active day pattern.
		Melanopsin also causes our pupils to constrict and dilate, and pupils don't work as well in people with low melanopsin levels.
	www.talkaboutsleep.com /sleep-disorders/2005/10/circadian-melanopsin-pupil-size.htm (292 words)

	Imperial College London - Researchers discover way to make cells in the eye sensitive to light
		The researchers believe that by activating the melanopsin, these cells may gain the ability to sense and respond to light.
		By switching on the melanopsin it could be possible to restore the eyes ability to respond to light.
		Although making cells in the eye responsive to light is not a cure for blindness, the team are collaborating with the Institute of Biomedical Engineering from Imperial to develop a functional retinal prosthesis which would allow the information from the light responsive cells to be used by the brain to process images.
	www.ic.ac.uk /P5952.htm (698 words)

	Dr. Ignacio Provencio
		Melanopsin is a novel retinaldehyde-based photopigment that we initially discovered in the dermal melanophores of Xenopus laevis.
		Taken together, these data suggest that melanopsin retinal ganglion cells may play a role in the photic regulation of mammalian circadian rhythms.
		While wild-type mice consolidate their activity to the dark phase and the time of activity onset is coincident with the light to dark transition, the mice lacking rods, cones, and melaopsin continue to free run with an intrinsic period length of less than 24hr.
	www.virginia.edu /biology/Fac/Provencio.html (734 words)

	Melanopsin Is Expressed in PACAP-Containing Retinal Ganglion Cells of the Human Retinohypothalamic Tract -- Hannibal et ...
		Melanopsin was expressed in retinas with severe degeneration of the outer and/or inner layers.
		The photopigment melanopsin is exclusively present in PACAP containing retinal ganglion cells of the retinohypothalamic tract.
		Melanopsin is required for non-image-forming photic responses in blind mice.
	www.iovs.org /cgi/content/full/45/11/4202 (3691 words)

Try your search on: Qwika (all wikis)