Relevant bibliographies by topics / Melanopsin

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Melanopsin'

Author: Grafiati
Published: 4 June 2021
Last updated: 24 January 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Melanopsin.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Melanopsin"

1

Spitschan, Manuel, Andrew S. Bock, Jack Ryan, Giulia Frazzetta, David H. Brainard, and Geoffrey K. Aguirre. "The human visual cortex response to melanopsin-directed stimulation is accompanied by a distinct perceptual experience." Proceedings of the National Academy of Sciences 114, no. 46 (October 31, 2017): 12291–96. http://dx.doi.org/10.1073/pnas.1711522114.

Full text
Abstract:
The photopigment melanopsin supports reflexive visual functions in people, such as pupil constriction and circadian photoentrainment. What contribution melanopsin makes to conscious visual perception is less studied. We devised a stimulus that targeted melanopsin separately from the cones using pulsed (3-s) spectral modulations around a photopic background. Pupillometry confirmed that the melanopsin stimulus evokes a response different from that produced by cone stimulation. In each of four subjects, a functional MRI response in area V1 was found. This response scaled with melanopic contrast and was not easily explained by imprecision in the silencing of the cones. Twenty additional subjects then observed melanopsin pulses and provided a structured rating of the perceptual experience. Melanopsin stimulation was described as an unpleasant, blurry, minimal brightening that quickly faded. We conclude that isolated stimulation of melanopsin is likely associated with a response within the cortical visual pathway and with an evoked conscious percept.
APA, Harvard, Vancouver, ISO, and other styles
2

Somasundaram, Preethi, Glenn R. Wyrick, Diego Carlos Fernandez, Alireza Ghahari, Cindy M. Pinhal, Melissa Simmonds Richardson, Alan C. Rupp, et al. "C-terminal phosphorylation regulates the kinetics of a subset of melanopsin-mediated behaviors in mice." Proceedings of the National Academy of Sciences 114, no. 10 (February 21, 2017): 2741–46. http://dx.doi.org/10.1073/pnas.1611893114.

Full text
Abstract:
Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin and mediate several non–image-forming visual functions, including circadian photoentrainment and the pupillary light reflex (PLR). ipRGCs act as autonomous photoreceptors via the intrinsic melanopsin-based phototransduction pathway and as a relay for rod/cone input via synaptically driven responses. Under low light intensities, where only synaptically driven rod/cone input activates ipRGCs, the duration of the ipRGC response will be determined by the termination kinetics of the rod/cone circuits. Little is known, however, about the termination kinetics of the intrinsic melanopsin-based phototransduction pathway and its contribution to several melanopsin-mediated behaviors. Here, we show that C-terminal phosphorylation of melanopsin determines the recovery kinetics of the intrinsic melanopsin-based photoresponse in ipRGCs, the duration of the PLR, and the speed of reentrainment. In contrast, circadian phase alignment and direct effects of light on activity (masking) are not influenced by C-terminal phosphorylation of melanopsin. Electrophysiological measurements demonstrate that expression of a virally encoded melanopsin lacking all C-terminal phosphorylation sites (C terminus phosphonull) leads to a prolonged intrinsic light response. In addition, mice expressing the C terminus phosphonull in ipRGCs reentrain faster to a delayed light/dark cycle compared with mice expressing virally encoded WT melanopsin; however, the phase angle of entrainment and masking were indistinguishable. Importantly, a sustained PLR in the phosphonull animals is only observed at brighter light intensities that activate melanopsin phototransduction, but not at dimmer light intensities that activate only the rod/cone pathway. Taken together, our results highlight how the kinetics of the melanopsin photoresponse differentially regulate distinct light-mediated behaviors.
APA, Harvard, Vancouver, ISO, and other styles
3

Woelders, Tom, Thomas Leenheers, Marijke C. M. Gordijn, Roelof A. Hut, Domien G. M. Beersma, and Emma J. Wams. "Melanopsin- and L-cone–induced pupil constriction is inhibited by S- and M-cones in humans." Proceedings of the National Academy of Sciences 115, no. 4 (January 8, 2018): 792–97. http://dx.doi.org/10.1073/pnas.1716281115.

Full text
Abstract:
The human retina contains five photoreceptor types: rods; short (S)-, mid (M)-, and long (L)-wavelength–sensitive cones; and melanopsin-expressing ganglion cells. Recently, it has been shown that selective increments in M-cone activation are paradoxically perceived as brightness decrements, as opposed to L-cone increments. Here we show that similar effects are also observed in the pupillary light response, whereby M-cone or S-cone increments lead to pupil dilation whereas L-cone or melanopic illuminance increments resulted in pupil constriction. Additionally, intermittent photoreceptor activation increased pupil constriction over a 30-min interval. Modulation of L-cone or melanopic illuminance within the 0.25–4-Hz frequency range resulted in more sustained pupillary constriction than light of constant intensity. Opposite results were found for S-cone and M-cone modulations (2 Hz), mirroring the dichotomy observed in the transient responses. The transient and sustained pupillary light responses therefore suggest that S- and M-cones provide inhibitory input to the pupillary control system when selectively activated, whereas L-cones and melanopsin response fulfill an excitatory role. These findings provide insight into functional networks in the human retina and the effect of color-coding in nonvisual responses to light, and imply that nonvisual and visual brightness discrimination may share a common pathway that starts in the retina.
APA, Harvard, Vancouver, ISO, and other styles
4

McGregor, K. M., C. Bécamel, P. Marin, and R. Andrade. "Using melanopsin to study G protein signaling in cortical neurons." Journal of Neurophysiology 116, no. 3 (September 1, 2016): 1082–92. http://dx.doi.org/10.1152/jn.00406.2016.

Full text
Abstract:
Our understanding of G protein-coupled receptors (GPCRs) in the central nervous system (CNS) has been hampered by the limited availability of tools allowing for the study of their signaling with precise temporal control. To overcome this, we tested the utility of the bistable mammalian opsin melanopsin to examine G protein signaling in CNS neurons. Specifically, we used biolistic (gene gun) approaches to transfect melanopsin into cortical pyramidal cells maintained in organotypic slice culture. Whole cell recordings from transfected neurons indicated that application of blue light effectively activated the transfected melanopsin to elicit the canonical biphasic modulation of membrane excitability previously associated with the activation of GPCRs coupling to Gαq-11. Remarkably, full mimicry of exogenous agonist concentration could be obtained with pulses as short as a few milliseconds, suggesting that their triggering required a single melanopsin activation-deactivation cycle. The resulting temporal control over melanopsin activation allowed us to compare the activation kinetics of different components of the electrophysiological response. We also replaced the intracellular loops of melanopsin with those of the 5-HT2A receptor to create a light-activated GPCR capable of interacting with the 5-HT2A receptor interacting proteins. The resulting chimera expressed weak activity but validated the potential usefulness of melanopsin as a tool for the study of G protein signaling in CNS neurons.
APA, Harvard, Vancouver, ISO, and other styles
5

Berman, SM, and RD Clear. "A practical metric for melanopic metrology." Lighting Research & Technology 51, no. 8 (January 29, 2019): 1178–91. http://dx.doi.org/10.1177/1477153518824147.

Full text
Abstract:
Over the past decade, there has been a growing interest in lighting research on the effects of the recently discovered melanopsin receptor (also referred to as the intrinsically photosensitive retinal ganglion cell) and its impacts on health and vision. Presently, there is not a generally accepted metrology for dealing with the spectral response of the melanopsin receptor as applied to both lighting and vision research. A proposition to handle this issue from a vision science perspective has been presented in 2014 in the journal Trends in Neurosciences and from a more lighting perspective in 2017 in Lighting Research and Technology. These propositions are complex, and do not retain the CIE standard definition of a lumen. In this paper, we propose an approach based on effective watts and melanopic/photopic ratios that is both simpler and more closely aligned with CIE standard unit definitions. In addition, we include some practical examples of how such ratios are accessible now, and can be used for both lighting and vision research as well as applications.
APA, Harvard, Vancouver, ISO, and other styles
6

SOLLARS, PATRICIA J., CYNTHIA A. SMERASKI, JESSICA D. KAUFMAN, MALCOLM D. OGILVIE, IGNACIO PROVENCIO, and GARY E. PICKARD. "Melanopsin and non-melanopsin expressing retinal ganglion cells innervate the hypothalamic suprachiasmatic nucleus." Visual Neuroscience 20, no. 6 (November 2003): 601–10. http://dx.doi.org/10.1017/s0952523803206027.

Full text
Abstract:
Retinal input to the hypothalamic suprachiasmatic nucleus (SCN) synchronizes the SCN circadian oscillator to the external day/night cycle. Retinal ganglion cells that innervate the SCN via the retinohypothalamic tract are intrinsically light sensitive and express melanopsin. In this study, we provide data indicating that not all SCN-projecting retinal ganglion cells express melanopsin. To determine the proportion of ganglion cells afferent to the SCN that express melanopsin, ganglion cells were labeled following transsynaptic retrograde transport of a recombinant of the Bartha strain of pseudorabies virus (PRV152) constructed to express the enhanced green fluorescent protein (EGFP). PRV152 injected into the anterior chamber of the eye retrogradely infects four retinorecipient nuclei in the brain via autonomic circuits to the eye, resulting in transneuronally labeled ganglion cells in the contralateral retina 96 h after intraocular infection. In animals with large bilateral lesions of the lateral geniculate body/optic tract, ganglion cells labeled with PRV152 are retrogradely infected from only the SCN. In these animals, most PRV152-infected ganglion cells were immunoreactive for melanopsin. However, a significant percentage (10–20%) of EGFP-labeled ganglion cells did not express melanopsin. These data suggest that in addition to the intrinsically light-sensitive melanopsin-expressing ganglion cells, conventional ganglion cells also innervate the SCN. Thus, it appears that the rod/cone system of photoreceptors may provide signals to the SCN circadian system independent of intrinsically light-sensitive melanopsin ganglion cells.
APA, Harvard, Vancouver, ISO, and other styles
7

VUGLER, ANTHONY A., MA'AYAN SEMO, ANNA JOSEPH, and GLEN JEFFERY. "Survival and remodeling of melanopsin cells during retinal dystrophy." Visual Neuroscience 25, no. 2 (March 2008): 125–38. http://dx.doi.org/10.1017/s0952523808080309.

Full text
Abstract:
AbstractThe melanopsin positive, intrinsically photosensitive retinal ganglion cells (ipRGCs) of the inner retina have been shown to send wide-ranging projections throughout the brain. To investigate the response of this important cell type during retinal dystrophy, we use the Royal College of Surgeons (RCS) dystrophic rat, a major model of retinal degeneration. We find that ipRGCs exhibit a distinctive molecular profile that remains unaltered during early stages of outer retinal pathology (15 weeks of age). In particular, these cells express βIII tubulin, α-acetylated tubulin, and microtubule-associated proteins (MAPs), while remaining negative for other RGC markers such as neurofilaments, calretinin, and parvalbumin. By 14 months of age, melanopsin positive fibers invade ectopic locations in the dystrophic retina and ipRGC axons/dendrites become distorted (a process that may involve vascular remodeling). The morphological abnormalities in melanopsin processes are associated with elevated immunoreactivity for MAP1b and a reduction in α-acetylated tubulin. Quantification of ipRGCs in whole mounts reveals reduced melanopsin cell number with increasing age. Focusing on the retinal periphery, we find a significant decline in melanopsin cell density contrasted by a stability of melanopsin positive processes. In addition to these findings, we describe for the first time, a distinct plexus of melanopsin processes in the far peripheral retina, a structure that is coincident with a short wavelength opsin cone-enriched rim. We conclude that some ipRGCs are lost in RCS dystrophic rats as the disease progresses and that this loss may involve vascular remodeling. However, a significant number of melanopsin positive cells survive into advanced stages of retinal degeneration and show indications of remodeling in response to pathology. Our findings underline the importance of early intervention in human retinal disease in order to preserve integrity of the inner retinal photoreceptive network.
APA, Harvard, Vancouver, ISO, and other styles
8

Lucas, Robert J., Annette E. Allen, Nina Milosavljevic, Riccardo Storchi, and Tom Woelders. "Can We See with Melanopsin?" Annual Review of Vision Science 6, no. 1 (September 15, 2020): 453–68. http://dx.doi.org/10.1146/annurev-vision-030320-041239.

Full text
Abstract:
A small fraction of mammalian retinal ganglion cells are directly photoreceptive thanks to their expression of the photopigment melanopsin. These intrinsically photosensitive retinal ganglion cells (ipRGCs) have well-established roles in a variety of reflex responses to changes in ambient light intensity, including circadian photoentrainment. In this article, we review the growing evidence, obtained primarily from laboratory mice and humans, that the ability to sense light via melanopsin is also an important component of perceptual and form vision. Melanopsin photoreception has low temporal resolution, making it fundamentally biased toward detecting changes in ambient light and coarse patterns rather than fine details. Nevertheless, melanopsin can indirectly impact high-acuity vision by driving aspects of light adaptation ranging from pupil constriction to changes in visual circuit performance. Melanopsin also contributes directly to perceptions of brightness, and recent data suggest that this influences the appearance not only of overall scene brightness, but also of low-frequency patterns.
APA, Harvard, Vancouver, ISO, and other styles
9

SEMO, MA'AYAN, MARTA MUÑOZ LLAMOSAS, RUSSELL G. FOSTER, and GLEN JEFFERY. "Melanopsin (Opn4) positive cells in the cat retina are randomly distributed across the ganglion cell layer." Visual Neuroscience 22, no. 1 (January 2005): 111–16. http://dx.doi.org/10.1017/s0952523805001069.

Full text
Abstract:
A rare type of rodent retinal ganglion cell expresses melanopsin (Opn4), the majority of which project to the suprachiasmatic nuclei. Many of these cells are directly light sensitive and appear to regulate the circadian system in the absence of rod and cone photoreceptors. However, the rodent retina contains no overt regions of specialization, and the different ganglion cell types are hard to distinguish. Consequently, attempts to distinguish the distribution of melanopsin ganglion cells in relation to regions of retinal specialization or subtype have proved problematic. Retinal cells with a common function tend to be regularly distributed. In this study, we isolate cat melanopsin and label melanopsin expressing cells usingin situhybridization. The labelled cells were all confined to the ganglion cell layer, their density was low, and their distribution was random. Melanopsin containing cells showed no clear center-to-periphery gradient in their distribution and were comprised of a relatively uniform cellular population.
APA, Harvard, Vancouver, ISO, and other styles
10

Conus, Vincent, and Martial Geiser. "A Review of Silent Substitution Devices for Melanopsin Stimulation in Humans." Photonics 7, no. 4 (November 30, 2020): 121. http://dx.doi.org/10.3390/photonics7040121.

Full text
Abstract:
One way to study the specific response of the non-visual melanopsin photoreceptors of the human eye is to silence the response of cones and rods. Melanopsin photoreceptors (ipRGC), highlighted in the early 2000s, are intimately linked to the circadian rhythm and therefore to our sleep and wakefulness. Rest and sleep regulation, health and cognitive functions are all linked to ipRGC and play an important role in work and human relationships. Thus, we believe that the study of ipRGC responses is important.We searched and reviewed scientific articles describing instrumentation dedicated to these studies. PubMed lists more than 90,000 articles created since the year 2000 that contain the word circadian but only 252 with silent substitution. In relation to melanopsin, we found 39 relevant articles from which only 11 give a device description for humans, which is incomplete in most cases. We did not find any consensus for light intensity description, melanopsin contrast, sequences of melanopsin light stimulation and optical setup to expose the retina to the light.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Melanopsin"

1

Teikari, Petteri. "spectral modulation of melanopsin responses : role of melanopsin bistability in pupillary light reflex." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00999326.

Full text
Abstract:
In addition to the canonical photoreceptors, rods and cones, a novelmelanopsin-expressing retinal ganglion cell (mRGC) was recently discovered.The novel photopigment melanopsin in the human retinahas been shown to express invertebrate-like bistable properties bothin vitro and in vivo. In bistable photopigment systems, light elicitsphotosensory responses and drives photoregeneration of the chromophoreto restore photic responsiveness. These studies have shownthat prior light exposure can modulate the amplitude of subsequentphotic responses of melanopsin.In this thesis, the putative bistability of melanopin in humans isexamined. The bistability was studied using 1) pupillary light reflex(PLR) as a tool, 2) developing a method for quantifying the effectsof lens density for melanopsin-mediated photoreception, and 3) providinga quantitative mathematical framework for modeling bistablepigment systems and non-image forming (NIF) visual system.Exploiting the bistable properties of melanopsin could allow foroptimization of spectral light distribution in experimental, industrial,domestic and clinical phototherapy applications by appropriate useof the photoregenerative effects of long wavelength light.
APA, Harvard, Vancouver, ISO, and other styles
2

Ramos, Bruno Cesar Ribeiro. "Fototransdução em células embrionárias ZEM-2S do peixe teleósteo Danio rerio." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-16012015-151748/.

Full text
Abstract:
A melanopsina foi descoberta em 1998 por Ignacio Provencio e colaboradores em melanóforos de Xenopus leavis. Desde sua descoberta, esse fotopigmento surgiu como um possível candidato a intermediar os fenômenos de sincronização nos vertebrados. Nos mamíferos, a melanopsina é encontrada num pequeno subgrupo de células ganglionares da retina, conhecido como células ganglionares retinianas intrinsecamente fotossensíveis (ipRGCs) e o seu papel como fotopigmento responsável pela percepção luminosa, que leva à sincronização das espécies dessa classe aos ciclos de claro e escuro, já foi estabelecido. A melanopsina está presente na retina de todas as classes de vertebrados estudadas até o momento, mas, em contraposição a essa afirmação, a sua estrutura tem maior semelhança com opsina de invertebrados do que com opsina de vertebrados, sugerindo que sua fototransdução ocorra através da via dos fosfoinositídeos. Essa hipótese foi confirmada por diversos trabalhos na literatura e estudos posteriores demonstraram que, em vertebrados não mamíferos, a melanopsina é codificada por dois genes: um ortólogo ao de mamíferos, Opn4m, e um ortólogo ao de X. leavis, Opn4x, levantando diversas questões a respeito da funcionalidade dessa opsina. Nosso grupo vem estudando esse fotopigmento nos tecidos periféricos de vertebrados desde 2001, sendo que foi pioneiro em demonstrar, em melanóforos de Xenopus laevis, que a dispersão dos grânulos de melanina se dá através da fotoativação da melanopsina que desencadeia a cascata de fosfoinositídeos. E estudos mais recentes vêm colocando a melanopsina como um dos possíveis fotopigmentos responsáveis pela sincronização de relógios periféricos em organismos como peixes e anfíbios. Nesse sentido, a linhagem de células ZEM-2S do peixe teleósteo Danio rerio é um ótimo modelo para o estudo das vias de fototransdução em relógios periféricos. Já foi demonstrado que essa linhagem de células é responsiva a estímulos luminosos, exibindo uma proliferação diferencial frente a diferentes regimes de claro e escuro, e ativando a expressão de genes de relógio como clock, per1 e cry1b, que conhecidamente são responsáveis por sincronizar os ritmos biológicos ao fotoperíodo ambiental. Nossos experimentos de imunocitoquímica detectaram a presença das duas proteínas codificadas pelos genes opn4m-1 e opn4m-2 da melanopsina, e mostraram uma significativa diferença na distribuição das proteínas Opn4m-1 e Opn4m-2. Análises de PCR quantitativo mostraram que um pulso de luz azul de 10 min é capaz de alterar a expressão dos genes de relógio per1b, per2, cry1a e cry1b, e que essa alteração ocorre através da via dos fosfoinositídeos em células embrionárias ZEM-2S de Danio rerio. Em adição mostramos que para promover a alteração dos genes de relógio, a via dos fosfoinositídeos interage com outras vias de sinalização como a via do óxido nítrico (NO) e a via das proteína quinases ativadas por mitógenos (MAPKs). Esses dados sugerem que a melanopsina seja um dos principais candidatos a intermediar os processos de sincronização nessas células, pois a somatória dos resultados de detecção da melanopsina, estimulação dentro de seu espectro de absorção e ativação da via dos fosfoinositídeos, a coloca a frente de outras opsinas como vertebrate ancient opsin (Va-opsin) e teleost multiple tissue opsin (Tmt-opsin) e de outros candidatos como Crys fotossensíveis e mecanismos de estresse oxidativo. No curso deste trabalho também conseguimos definir metodologias eficientes de transfecção de RNA de interferência e de DNA plasmidial em células ZEM-2S de D. rerio, que são ferramentas fundamentais nos estudos de expressão gênica nesse modelo
Melanopsin was discovered in 1998 by Ignacio Provencio and colleagues in Xenopus leavis melanophores. Since its discovery, this photopigment has emerged as a possible candidate to mediate synchronization in vertebrates. In mammals the melanopsin is found in a subset of retinal ganglion cells, known as intrinsically photosensitive retinal ganglion cells (ipRGCs) and their role as the photopigment responsible for photoentrainment in mammals has already been established. Melanopsin is present in the retina of all vertebrate classes studied to date, nevertheless, its structure is more similar to invertebrate than to vertebrates opsins, suggesting that their phototransduction pathway occurs through the phosphoinositide pathway. This hypothesis has been confirmed by several studies in the literature. Later studies showed that melanopsin is encoded by two genes in non-mammalian vertebrates, Opn4m orthologous to mammalian and Opn4x orthologous to X. leavis, raising new questions about the functionality of this opsin. Our group has studied this photopigment in vertebrate peripheral tissues since 2001 and, in Xenopus laevis melanophores, we demonstrated that pigment granule dispersion occurs through photoactivation of melanopsin and triggering of phosphoinositide pathway. More recent studies have put melanopsin as a possible photoreceptor responsible for peripheral clocks entrainment in organisms like fish and amphibians. In this context, the ZEM-2S cell line of the teleost fish Danio rerio is a good model to study the mechanism of phototransduction in peripheral clocks. It has been previously demonstrated that this cell line is responsive to light stimuli, exhibiting a differential proliferation when submitted to different light/dark regimes and activating the expression of clock genes such as clock, per1 and cry1b, known to synchronize the biological rhythms to environmental photoperiod. Our immunocytochemistry experiments detected the presence of two proteins encoded by the melanopsin genes opn4m-1 and opn4m-2, and showed a significant difference in the distribution of proteins Opn4m-1 Opn4m-2. Quantitative PCR analyses showed that a 10-min blue light pulse is able to change the expression of the clock genes per1b, per2, cry1b and cry1a, and that this change occurred through the phosphoinositide cascade in embryonic ZEM-2S cells of D. rerio. In addition we showed that, to promote the change in clock gene expression, the phosphoinositide pathway interacts with other signaling pathways such as the nitric oxide (NO) and the mitogen-activated protein kinase (MAPK) pathways. These data suggest that melanopsin is a major candidate to mediate the photoentrainment in these cells, because taken together, the detection of melanopsin, stimulation within its absorption spectrum and activation of the phosphoinositide cascade, puts it ahead of other opsins, as the vertebrate ancient opsin (Va-opsin) and teleost multiple tissue opsin (Tmt-opsin), and other candidates, as photosensitive Crys and mechanisms of oxidative stress. In the course of this work, we could also define efficient methods for transfection of interference RNA and plasmidial DNA in ZEM-2S cells of D. rerio, which are fundamental tools in studies of gene expression in this model
APA, Harvard, Vancouver, ISO, and other styles
3

Roecklein, Kathryn Ariel. "Melanopsin polymorphisms in seasonal affective disorder /." Download the thesis in PDF, 2005. http://www.lrc.usuhs.mil/dissertations/pdf/Roecklein2005.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Santos, Luciane Rogéria dos. "Expressão gênica de receptor de melatonina (Mel1) e melanopsinas (Opn4x e Opn4m) em melanóforos de Xenopus laevis." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-09022011-104538/.

Full text
Abstract:
Muitos vertebrados ectotérmicos ajustam suas cores corporais para serem confundidos com o ambiente, através da migração de pigmentos no interior de cromatóforos, regulada por sistemas neurais e/ou hormonais. Essas mudanças de coloração auxiliam no mimetismo, termorregulação, comunicação social e expressão de comportamentos como excitação sexual, agressividade e medo. Entretanto, cromatóforos de inúmeras espécies respondem diretamente à luz. Estudos sobre a resposta à luz nos melanóforos de Xenopus laevis levaram à descoberta do fotopigmento melanopsina, uma opsina que está presente na retina de todos os grupos de vertebrados, inclusive no homem. Vários hormônios podem regular o processo de mudança de cor nos vertebrados, dentre eles a melatonina, hormônio secretado pela glândula pineal. Este é o principal órgão responsável pela integração do sistema neuroendócrino dos vertebrados ao meio ambiente, traduzindo direta ou indiretamente a informação do fotoperíodo em sinal hormonal, coordenando assim os ritmos fisiológicos circadianos com o meio ambiente. Os objetivos deste trabalho foram: investigar se a expressão gênica das melanopsinas e do receptor de melatonina em melanóforos de Xenopus laevis apresenta variação temporal sob diferentes condições luminosas; verificar se a expressão gênica das melanopsinas e do receptor de melatonina em melanóforos de Xenopus laevis pode ser modulada por melatonina. Dados do trabalho demonstram que as melanopsinas em melanóforos de Xenopus laevis são sincronizadas aos ciclos de claro-escuro, expressando um robusto ritmo ultradiano com período de 16h para Opn4m e um ritmo circadiano com período de 25h para Opn4x. Curiosamente, essa ritmicidade só foi observada quando os melanóforos foram mantidos em ciclos 12C:12E e foram submetidos à troca de meio durante a fase clara do fotoperíodo. A constância na expressão gênica do receptor de melatonina Mel1, quer sob diferentes regimes de luz, quer sob tratamento por melatonina, sugere que esse gene é extremamente estável, não sofrendo alterações ao ser submetido a estímulos exógenos, podendo ser considerado um gene constitutivo. O tratamento com melatonina por 6h na fase clara do fotoperíodo, além de inibir drasticamente a expressão de Opn4x e Opn4m, aboliu a ritimicidade de ambas as melanopsinas. Nossos resultados indicam que os melanóforos de Xenopus laevis possuem um relógio funcional e podem ser caracterizados como relógios periféricos, porém necessitam do ciclo claro-escuro associado à troca de meio para exibirem sua sincronização.
Many ectothermic vertebrates adjust their body color to mimic the environment, through the pigment migration within chromatophores, regulated by neural and / or hormonal systems. These changes in color help in camouflage, thermoregulation, social communication and behaviors such as sexual arousal, agressiveness and fear. However, chromatophores of several species respond directly to light. Studies about light response in melanophores of Xenopus laevis have led to the discovery of the photopigment melanopsin, an opsin that is present in the retina of all vertebrate groups, including man. Various hormones may regulate the process of color change in vertebrates, among them melatonin, hormone secreted by the pineal gland. This is the main organ responsible for the integration of the neuroendocrine system of vertebrates to the environment, translating directly or indirectly the photoperiod information into hormonal signal, thus coordinating physiological circadian rhythms with the environment. The objectives of this work were: to investigate whether the gene expression of melanopsins and melatonin receptor in melanophores of Xenopus laevis exhibited temporal variation under different light conditions; to verify whether gene expression of melanopsins and melatonin receptor in melanophores of Xenopus laevis could be modulated by melatonin. Our data show that melanopsins in melanophores of Xenopus laevis are synchronized to light-dark cycles, expressing a robust ultradian rhythm with a period of 16h for Opn4m and circadian rhythm with a period of 25h for Opn4x. Interestingly, the rhythm was only observed when the melanophores were maintained in 12L: 12D regime and medium change was performed during the fotophase of photoperiod. The constancy in the expression of melatonin receptor Mel1c, either under different light regimes, or under treatment by melatonin, suggesting that this gene is extremely stable, not being altered by exogenous stimulus, and may be considered a constitutive gene. Treatment with melatonin for 6h during the fotophase of the photoperiod, drastically inhibit the expression of Opn4x and Opn4m, and abolished the rhythm of both melanopsins. Our results indicate that melanophores of Xenopus laevis possess a functional clock and can be characterized as peripheral clocks, but they need the light-dark cycle associated with change of medium to exhibit their synchronization.
APA, Harvard, Vancouver, ISO, and other styles
5

Moraes, Maria Nathália de Carvalho Magalhães. "Efeito da endotelina sobre a expressão gênica das melanopsinas (Opn4x e Opn4m) e do receptor de endotelina, subtipo ETc, em melanóforo de Xenopus laevis." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-18022011-104223/.

Full text
Abstract:
Os relógios biológicos são fundamentais para a sincronização do comportamento dos organismos a mudanças no fotoperíodo. Todas as alterações rítmicas são determinantes para a sobrevivência da espécie uma vez que elas prevêem que os ajustes internos coincidam com a fase mais propícia do ciclo ambiental, permitindo aos organismos a capacidade de sincronizar esses eventos internos com os ciclos ambientais. Muitos desses ritmos biológicos são claramente associados ao ciclo claro-escuro, sendo este ciclo de grande importância para as espécies que possuem algum tipo de pigmento fotossensível. Os melanóforos de Xenopus laevis são fotossensíveis, respondendo à luz com dispersão dos grânulos de melanina, devido à presença de duas melanopsinas, Opn4x e Opn4m. As células pigmentares dos vertebrados heterotérmicos respondem com migração pigmentar a uma variedade de agentes, incluindo as endotelinas. Em peixes teleósteos, ETs induzem a agregação pigmentar em melanóforos, enquanto que em anfíbios, ET-3 induz a dispersão de grânulos de pigmentos em melanóforos de Xenopus laevis e de Rana catesbeiana, através da ativação de receptores ETc. Propusemos determinar o padrão temporal de expressão dos genes das melanopsinas e do receptor ETc em melanóforos dérmicos de X. laevis em cultura, bem como os efeitos temporais e dose- dependentes da endotelina sobre essa expressão. Demonstramos, através de ensaios de PCR quantitativo, que o tratamento de 12C:12E , somado a uma troca de meio, assim como o de endotelina-3 10-9 e 10-8M em escuro constante, foi capaz de sincronizar a expressão de Opn4x e Opn4m. Entretanto, o receptor ETc parece não ser sincronizado pelo ciclo claro-escuro, ou pelo tratamento hormonal. Dependendo da dose utilizada e do ZT analisado, ET-3 pode promover um aumento ou inibição da expressão gênica de Opn4x, Opn4m e ETc, indicando uma modulação de forma dose-dependente. Além disso, pode atuar como um agente sincronizador da expressão dos transcritos das melanopsinas.
The biological clocks are critical for synchronizing the behavior of organisms to changes in photoperiod. All rhythmic changes are crucial to the survival of the species since they provide for internal adjustments to coincide with the phase of the cycle most favorable. Many of these biological rhythms are clearly associated with the light-dark cycle, of major importance for species that have some type of photosensitive pigment. Melanophores of Xenopus laevis are photosensitive, responding to light with dispersion of melanin granules, due to the presence of two melanopsins, Opn4x and Opn4m. The pigment cells of ectothermic vertebrates respond with pigment migration to a variety of agents including the endothelins. In teleost fish, ETs induce pigment aggregation in melanophores, whereas in amphibians, ET-3 induces the dispersion of pigment granules in melanophores of Xenopus laevis and Rana catesbeiana, by activation of ETc. We proposed to determine the temporal pattern of gene expression of the ETc receptor and melanopsins in dermal melanophores of X. laevis in culture as well as the effects of endothelin-3 on the temporal expression of the 3 genes. Using quantitative PCR, we demonstrated that 12L: 12D regimen, combined with medium changes, as well as the treatment with 10-9 and 10-8M endothelin-3, was able to synchronize the expression of Opn4x and Opn4m. However, ETc receptor seems not to be synchronized by light-dark cycle, or hormone treatment. Depending on the dose and the ZT, ET-3 may promote an increase or inhibition of gene expression of Opn4x, Opn4m and ETc, indicating a dose-dependent modulatory effect. In addition, endothelin-3 may also act as a synchronizing agent of the melanopsins transcripts.
APA, Harvard, Vancouver, ISO, and other styles
6

Hough, Katherine Ann. "Photodispersion and melanopsin expression in Xenopus laevis melanophores." Thesis, King's College London (University of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416960.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Dey, Ashim. "Melanopsin photoreceptor contributions to brightness perception and photophobia." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/205723/1/Ashim_Dey_Thesis.pdf.

Full text
Abstract:
This thesis investigated the role of rod, cone and melanopsin photoreceptors in mediating human brightness perception across the natural operating range of the eye. In scotopic illumination, brightness perception is initiated by rod signals transmitted to higher brain centres via conventional retinogeniculate and melanopsin pathways. In mesopic illumination, melanopsin photoreception begins to scale brightness perception. In photopic illumination, melanopsin and cone luminance signals combine to mediate light hypersensitivity (photophobia) in healthy controls and migraineurs. These findings advance understanding of the relative photoreceptor contributions to human vision and guide the development of lighting technologies for individuals who experience disease-related photophobia.
APA, Harvard, Vancouver, ISO, and other styles
8

Vachtsevanos, Athanasios. "Probing the molecular basis of melanopsin induced light sensitivity." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:631deeeb-90c0-4e90-b24e-f03e1b318d8b.

Full text
Abstract:
It has been demonstrated that retinal photoreception among mammals extends beyond rods and cones to include a small number of intrinsically photosensitive retinal ganglion cells (pRGCs), which are capable of responding to light due to expression of the melanopsin (OPN4) photopigment. OPN4 may have therapeutic potential if ectopically expressed in the degenerate retina in cases where photoreceptors are lost, but the other molecules involved in this light induced transduction cascade are less well characterized. Therefore I sought to probe further the mechanism of OPN4 mediated light sensitivity by siRNA mediated knock down of specific molecules in two mice models in which complete loss of rods and cones renders them almost exclusively dependent on the OPN4 pathway for light sensitivity. I generated siRNA probes against the long transcript variant of murine Opn4 mRNA and first tested these probes on the murine Neuro2A (N2a) cell line, before assessing effects in C3H/HeN rd and rodless/coneless rd/rd cl mice. siRNA was injected intravitreally into one eye and pupillometry was assessed, combined with molecular analyses at various timepoints. Reverse transcription polymerase chain reaction (RT-PCR) analysis in N2a cells confirmed Opn4 knockdown and immunolabelling techniques identified >85% silencing with siRNA. Pupil responses in the rd and rd/rd cl mice were inhibited by the siRNA injections in vivo which confirmed the functional effect of Opn4 silencing detected by molecular analysis. I therefore present a novel reproducible in vivo model in which siRNA induced silencing of the melanopsin pathway can be assessed by pupillometry and compared to levels of mRNA and protein at specific timepoints. Probes against other putative candidate genes, such as TRPC3, may unravel the molecular interactions of this pathway. This may help in future to induce light sensitivity in other retinal neurons in patients who are completely blind from photoreceptor loss.
APA, Harvard, Vancouver, ISO, and other styles
9

Rodgers, Jessica. "Functional characterisation of key residues in the photopigment melanopsin." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:d1184150-9b61-4cc9-94ad-2cc13a3d21ce.

Full text
Abstract:
Melanopsin (Opn4) is the opsin photopigment of intrinsically photosensitive retinal ganglion cells (ipRGCs). It has a conserved opsin structure and activation mechanism, yet demonstrates unusual functional properties that suggest it will possess unique structure-function relationships. The aim of this thesis was to characterise key OPN4 residues by examining the impact of non-synonymous mutations on melanopsin function. A genotype-driven screen of a chemically-mutagenized mouse archive led to the identification of a novel Opn4 mutant, S310A, located at a known opsin spectral tuning site. Action spectra from ipRGC and pupil light responses (PLR) of Opn4S310A mice revealed no change in wavelength of peak sensitivity. However, Opn4S310A PLR was significantly less sensitive at longer wavelengths, consistent with a short-wavelength shift in spectral sensitivity. This suggests S310A acts as a spectral tuning site in melanopsin. Next, the impact of naturally-occurring missense variants in human melanopsin (hOPN4) was examined in vitro. Fluorescent calcium imaging of 16 hOPN4 variants expressed in HEK293 cells revealed four hOPN4 variants abolished or attenuated responses to light (Y146C, R168C, G208S and S308F). These variants were located in conserved opsin motifs for chromophore binding or hydrogen-bond networks, functional roles apparently shared by melanopsin. Finally, two hOPN4 single nucleotide polymorphisms (SNPs) P10L and T394I, associated with abnormal non-image forming behaviour in humans, were explored in vivo. Using targeted viral-delivery of hOPN4 SNPs to mouse ipRGCs, a range of OPN4-driven behaviours, such as circadian photoentrainment and pupil light responses, were found to be comparable with hOPN4 WT control. Multi-electrode array recordings of ipRGCs transduced with hOPN4 T394I virus had significantly attenuated sensitivity and faster response offset, indicating this site may be functionally important for melanopsin activity but compensatory rod and cone input limits changes to non-image forming behaviour.
APA, Harvard, Vancouver, ISO, and other styles
10

Papamichael, Christiana. "Non-visual light responses in humans : melanopsin and cone involvement." Thesis, University of York, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.583379.

Full text
Abstract:
Melanopsin containing intrinsically photosensitive retinal ganglion cells (ipRGCs) are primarily sensitive blue light (- 480 nm) irradiance detectors that mediate non-visual responses (NVRs) such as melatonin suppression by light and alteration of mood and alertness levels. Also, ipRGCs integrate inputs from rods and cones that are content dependent and enable fine-tuning of light-dependent NVR.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Melanopsin"

1

Lai, Han-Lin. Estimation of tag loss rate of black rockfish (Sebastes melanops) off Washington coast with a review of double tagging models. Olympia, WA: State of Washington, Dept. of Fisheries, 1991.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
2

Joyce, Daniel S., Kevin W. Houser, Stuart N. Peirson, Jamie M. Zeitzer, and Andrew J. Zele. Melanopsin Vision: Sensation and Perception Through Intrinsically Photosensitive Retinal Ganglion Cells. Cambridge University Press, 2022.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

Joyce, Daniel S., Kevin W. Houser, Stuart N. Peirson, Jamie M. Zeitzer, and Andrew J. Zele. Melanopsin Vision: Sensation and Perception Through Intrinsically Photosensitive Retinal Ganglion Cells. Cambridge University Press, 2023.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
4

Scudder, Samuel Hubbard. Revision of the Orthopteran Group Melanopli: With Special Reference to North American Forms; Volume 20. Creative Media Partners, LLC, 2018.

Find full text
APA, Harvard, Vancouver, ISO, and other styles

Book chapters on the topic "Melanopsin"

1

Lucas, Robert. "Melanopsin Retinal Ganglion Cells." In Encyclopedia of Color Science and Technology, 1–3. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-27851-8_275-1.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Lucas, Robert. "Melanopsin Retinal Ganglion Cells." In Encyclopedia of Color Science and Technology, 1–4. Berlin, Heidelberg: Springer Berlin Heidelberg, 2019. http://dx.doi.org/10.1007/978-3-642-27851-8_275-2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Lucas, Robert. "Melanopsin Retinal Ganglion Cells." In Encyclopedia of Color Science and Technology, 901–3. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4419-8071-7_275.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Tsujimura, Sei-ichi, and Yoshika Takahashi. "Melanopsin Contributions to Human Brightness Perception." In Encyclopedia of Color Science and Technology, 1–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 2020. http://dx.doi.org/10.1007/978-3-642-27851-8_422-1.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Brown, R. Lane, Erika Camacho, Evan G. Cameron, Christina Hamlet, Kathleen A. Hoffman, Hye-Won Kang, Phyllis R. Robinson, Katherine S. Williams, and Glenn R. Wyrick. "A Stochastic Model of the Melanopsin Phototransduction Cascade." In The IMA Volumes in Mathematics and its Applications, 175–95. New York, NY: Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4939-2782-1_8.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Davies, Wayne I. L., Russell G. Foster, and Mark W. Hankins. "The Evolution and Function of Melanopsin in Craniates." In Evolution of Visual and Non-visual Pigments, 23–63. Boston, MA: Springer US, 2014. http://dx.doi.org/10.1007/978-1-4614-4355-1_2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Do, Michael Tri Hoang. "Patch-Clamp Electrophysiological Analysis of Murine Melanopsin Neurons." In Circadian Clocks, 121–50. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2577-4_6.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Mederos, Sara, Candela González-Arias, and Gertrudis Perea. "Melanopsin for Time-Controlling Activation of Astrocyte–Neuron Networks." In Methods in Molecular Biology, 53–69. New York, NY: Springer US, 2020. http://dx.doi.org/10.1007/978-1-0716-0755-8_3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Provencio, Ignacio. "The Role of Melanopsin and Other Opsins in Circadian Clock Resetting." In Biologic Effects of Light 2001, 451–59. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0937-0_44.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Lee, Seul Ki, and Tiffany M. Schmidt. "Morphological Identification of Melanopsin-Expressing Retinal Ganglion Cell Subtypes in Mice." In Methods in Molecular Biology, 275–87. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-7720-8_19.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Melanopsin"

1

Geiser, Martial, Frederic Truffer, Chirojean Balachandran, Aki Kawasaki, and Sergiu Agrici. "Device for silent substitution excitation of melanopsin for human eye." In Ophthalmic Technologies XXIX, edited by Fabrice Manns, Per G. Söderberg, and Arthur Ho. SPIE, 2019. http://dx.doi.org/10.1117/12.2511654.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Yamashita, Shuhei, Tomoe Uehara, Minako Matsuo, Yo Kikuchi, and Rika Numano. "Melanopsin resets circadian rhythms in cells by inducing clock gene Period1." In THE IRAGO CONFERENCE 2013. AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4866616.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Adhikari, Prakash, Andrew J. Zele, Dingcai Cao, Jan Kremers, and Beatrix Feigl. "The Influence of Melanopsin Activation on the Cone-mediated Photopic White Noise Electroretinogram (wnERG) in Humans." In Frontiers in Optics. Washington, D.C.: OSA, 2018. http://dx.doi.org/10.1364/fio.2018.jtu3a.109.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Patrick, Fluckiger, Schmid Jessica, Evequoz Gilles, Bressy Pierre, and Geiser Martial. "Homogeneous light stimulation of melanopsin and cones with a Maxwellian view device for the human eye." In 2021 IEEE International Instrumentation and Measurement Technology Conference (I2MTC). IEEE, 2021. http://dx.doi.org/10.1109/i2mtc50364.2021.9459940.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Schilling, Tim, Mojtaba Soltanlou, Yeshwanth Seshadri, Hans-Christoph Nuerk, and Hamed Bahmani. "Blue Light and Melanopsin Contribution to the Pupil Constriction in the Blind-spot, Parafovea and Periphery." In 13th International Conference on Health Informatics. SCITEPRESS - Science and Technology Publications, 2020. http://dx.doi.org/10.5220/0008972404820489.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Allen, Annette E., Franck P. Martial, and Robert J. Lucas. "Applying the discovery of melanopsin photoreceptors in the human retina to enhancing the performance of visual displays." In Advances in Display Technologies IX, edited by Qiong-Hua Wang, Tae-Hoon Yoon, and Jiun-Haw Lee. SPIE, 2019. http://dx.doi.org/10.1117/12.2508422.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Price, Luke. "BLH, LEDS AND CCT EQUIVALENT MELANOPIC ILLUMINANCES." In CIE 2017 Midterm Meetings and Conference on Smarter Lighting for Better Life. International Commission on Illumination, CIE, 2018. http://dx.doi.org/10.25039/x44.2017.pp31.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Parker, S. J., P. S. Rankin, J. M. Olson, and R. W. Hannah. "Movement patterns of black rockfish (Sebastes melanops) in Oregon coastal waters." In Biology, Assessment, and Management of North Pacific Rockfishes. Alaska Sea Grant, University of Alaska Fairbanks, 2007. http://dx.doi.org/10.4027/bamnpr.2007.03.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Kruisselbrink, T. W., R. Dangol, and E. J. van Loenen. "HDR IMAGING FOR LUMINANCE AND MELANOPIC RADIANCE: CAMERAS AND SPECTRAL POWER DISTRIBUTIONSRACT TITLE." In CIE Tutorials on Colorimetry and Visual Appearance. International Commission on Illumination (CIE), 2020. http://dx.doi.org/10.25039/x47.2020.pp07.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Durmus, Dorukalp. "Impact of Surface Reflectance on Spectral Optimization for Melanopic Illuminance and Energy Efficiency." In Optical Devices and Materials for Solar Energy and Solid-state Lighting. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/pvled.2019.pt2c.5.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Melanopsin"

1

Roecklein, Kathryn A. Haplotype Analysis of the Melanopsin Gene in Seasonal Affective Disorder and Controls. Fort Belvoir, VA: Defense Technical Information Center, May 2007. http://dx.doi.org/10.21236/ad1014058.

Full text
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Melanopsin' for particular source types:
Journal articles Dissertations / Theses
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography