Base de dados : MEDLINE
Pesquisa : E05.196.712.726.300 [Categoria DeCS]
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[PMID]:29253012
[Au] Autor:Vongsvivut J; Truong VK; Al Kobaisi M; Maclaughlin S; Tobin MJ; Crawford RJ; Ivanova EP
[Ad] Endereço:Infrared Microspectroscopy (IRM) Beamline, Australian Synchrotron, Clayton, Victoria, Australia.
[Ti] Título:Synchrotron macro ATR-FTIR microspectroscopic analysis of silica nanoparticle-embedded polyester coated steel surfaces subjected to prolonged UV and humidity exposure.
[So] Source:PLoS One;12(12):e0188345, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Surface modification of polymers and paints is a popular and effective way to enhance the properties of these materials. This can be achieved by introducing a thin coating that preserves the bulk properties of the material, while protecting it from environmental exposure. Suitable materials for such coating technologies are inorganic oxides, such as alumina, titania and silica; however, the fate of these materials during long-term environmental exposure is an open question. In this study, polymer coatings that had been enhanced with the addition of silica nanoparticles (SiO2NPs) and subsequently subjected to environmental exposure, were characterized both before and after the exposure to determine any structural changes resulting from the exposure. High-resolution synchrotron macro ATR-FTIR microspectroscopy and surface topographic techniques, including optical profilometry and atomic force microscopy (AFM), were used to determine the long-term effect of the environment on these dual protection layers after 3 years of exposure to tropical and sub-tropical climates in Singapore and Queensland (Australia). Principal component analysis (PCA) based on the synchrotron macro ATR-FTIR spectral data revealed that, for the 9% (w/w) SiO2NP/polymer coating, a clear discrimination was observed between the control group (no environmental exposure) and those samples subjected to three years of environmental exposure in both Singapore and Queensland. The PCA loading plots indicated that, over the three year exposure period, a major change occurred in the triazine ring vibration in the melamine resins. This can be attributed to the triazine ring being very sensitive to hydrolysis under the high humidity conditions in tropical/sub-tropical environments. This work provides the first direct molecular evidence, acquired using a high-resolution mapping technique, of the climate-induced chemical evolution of a polyester coating. The observed changes in the surface topography of the coating are consistent with the changes in chemical composition.
[Mh] Termos MeSH primário: Materiais Revestidos Biocompatíveis/química
Umidade
Microespectrofotometria
Nanopartículas/química
Poliésteres/química
Dióxido de Silício/química
Aço/química
Síncrotrons
[Mh] Termos MeSH secundário: Meio Ambiente
Espectroscopia Fotoeletrônica
Análise de Componente Principal
Espectroscopia de Infravermelho com Transformada de Fourier
Análise Espectral Raman
Raios Ultravioleta
Água/química
Molhabilidade
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Coated Materials, Biocompatible); 0 (Polyesters); 059QF0KO0R (Water); 12597-69-2 (Steel); 7631-86-9 (Silicon Dioxide)
[Em] Mês de entrada:1801
[Cu] Atualização por classe:180108
[Lr] Data última revisão:
180108
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171219
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0188345


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[PMID]:28684254
[Au] Autor:Mattana S; Alunni Cardinali M; Caponi S; Casagrande Pierantoni D; Corte L; Roscini L; Cardinali G; Fioretto D
[Ad] Endereço:Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, I-06123 Perugia, Italy. Electronic address: sara.mattana@studenti.unipg.it.
[Ti] Título:High-contrast Brillouin and Raman micro-spectroscopy for simultaneous mechanical and chemical investigation of microbial biofilms.
[So] Source:Biophys Chem;229:123-129, 2017 Oct.
[Is] ISSN:1873-4200
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Mechanical mapping with chemical specificity of biological samples is now made possible by joint micro-Brillouin and micro-Raman measurements. In this work, thanks to the unprecedented contrast of a new tandem Fabry-Perot interferometer, we demonstrate simultaneous detection of Brillouin and Raman spectra from different Candida biofilms. Our proof-of-concept study reveals the potential of this label-free joint micro-spectroscopy technique in challenging microbiological issues. In particular, heterogeneous chemo-mechanical maps of Candida biofilms are obtained, without the need for staining or touching the sample. The correlative Raman and Brillouin investigation evidences the role of both extracellular polymeric substances and of hydration water in inducing a marked local softening of the biofilm.
[Mh] Termos MeSH primário: Biofilmes
Candida/química
Técnicas Microbiológicas/métodos
Microespectrofotometria
Análise Espectral Raman
[Mh] Termos MeSH secundário: Candida/fisiologia
Módulo de Elasticidade
Técnicas Microbiológicas/instrumentação
Viscosidade
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171010
[Lr] Data última revisão:
171010
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170708
[St] Status:MEDLINE


  3 / 543 MEDLINE  
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[PMID]:28359344
[Au] Autor:Sato S; Frederiksen R; Cornwall MC; Kefalov VJ
[Ad] Endereço:Department of Ophthalmology and Visual Sciences,Washington University School of Medicine,Saint Louis,Missouri 63110.
[Ti] Título:The retina visual cycle is driven by cis retinol oxidation in the outer segments of cones.
[So] Source:Vis Neurosci;34:E004, 2017 01.
[Is] ISSN:1469-8714
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Vertebrate rod and cone photoreceptors require continuous supply of chromophore for regenerating their visual pigments after photoactivation. Cones, which mediate our daytime vision, demand a particularly rapid supply of 11-cis retinal chromophore in order to maintain their function in bright light. An important contribution to this process is thought to be the chromophore precursor 11-cis retinol, which is supplied to cones from Müller cells in the retina and subsequently oxidized to 11-cis retinal as part of the retina visual cycle. However, the molecular identity of the cis retinol oxidase in cones remains unclear. Here, as a first step in characterizing this enzymatic reaction, we sought to determine the subcellular localization of this activity in salamander red cones. We found that the onset of dark adaptation of isolated salamander red cones was substantially faster when exposing directly their outer vs. their inner segment to 9-cis retinol, an analogue of 11-cis retinol. In contrast, this difference was not observed when treating the outer vs. inner segment with 9-cis retinal, a chromophore analogue which can directly support pigment regeneration. These results suggest, surprisingly, that the cis-retinol oxidation occurs in the outer segments of cone photoreceptors. Confirming this notion, pigment regeneration with exogenously added 9-cis retinol was directly observed in the truncated outer segments of cones, but not in rods. We conclude that the enzymatic machinery required for the oxidation of recycled cis retinol as part of the retina visual cycle is present in the outer segments of cones.
[Mh] Termos MeSH primário: Células Fotorreceptoras Retinianas Cones/fisiologia
Segmento Externo das Células Fotorreceptoras da Retina/fisiologia
Visão Ocular/fisiologia
Vitamina A/metabolismo
[Mh] Termos MeSH secundário: Ambystoma
Animais
Adaptação à Escuridão
Microespectrofotometria
Oxirredução
Estimulação Luminosa
Pigmentos da Retina/metabolismo
Retinaldeído/farmacologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T; RESEARCH SUPPORT, N.I.H., EXTRAMURAL
[Nm] Nome de substância:
0 (Retinal Pigments); 11103-57-4 (Vitamin A); 514-85-2 (9-cis-retinal); RR725D715M (Retinaldehyde)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:171120
[Lr] Data última revisão:
171120
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170401
[St] Status:MEDLINE
[do] DOI:10.1017/S0952523817000013


  4 / 543 MEDLINE  
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[PMID]:28303339
[Au] Autor:Bittencourt Júnior NS
[Ad] Endereço:Departamento de Zoologia e Botânica, Instituto de Biociências Letras e Ciências Exatas, Universidade Estadual Paulista "Júlio de Mesquita Filho", Rua Cristóvão Colombo 2265, Jardim Nazareth, CEP 15054-000, São José do Rio Preto, São Paulo, Brazil. nesbitte@ibilce.unesp.br.
[Ti] Título:Evidence for post-zygotic self-incompatibility in Handroanthus impetiginosus (Bignoniaceae).
[So] Source:Plant Reprod;30(2):69-79, 2017 Jun.
[Is] ISSN:2194-7961
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:Late-acting self-incompatibility (LSI) has been defined as a genetically controlled self-sterility mechanism that prevents seed set by selfing, despite normal pollen tube growth and ovule penetration in self-pollinated pistils. In species of the Bignoniaceae with LSI, such as Handroanthus impetiginosus, the selfed pistils are characterized by a marked delay in ovule penetration, fertilization, and endosperm initiation, followed by uniform pistil abscission. This highlights the contentious possibility of a post-zygotic self-incompatibility system. However, previous studies were unable to confirm fusion of the sperm and egg cell nuclei in selfed ovules. In the present study, the cytology of the embryo sac, double fertilization, and pistil longevity was investigated in H. impetiginosus using comparative nuclei microspectrofluorometry of DAPI-stained sections of self- vs. unpollinated pistils. Differences in both pistil longevity and ovary size between self- and unpollinated flowers at the time of pistil abscission were significant. Zygotes with double the DNA content in their nuclei relative to unfertilized egg cell nuclei were verified in selfed ovules from the first day after pollination onward, and G1 karyogamy appeared to have occurred. Our cytological analysis clearly indicates that ovules of self-pollinated pistils in H. impetiginosus are fertilized before pistil abscission but no embryogenesis initiation occurs, which strongly supports the idea of a post-zygotic self-incompatibility mechanism.
[Mh] Termos MeSH primário: Bignoniaceae/fisiologia
Autoincompatibilidade em Angiospermas
[Mh] Termos MeSH secundário: Bignoniaceae/genética
DNA de Plantas
Flores/fisiologia
Microespectrofotometria
Polinização
Autoincompatibilidade em Angiospermas/genética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (DNA, Plant)
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171108
[Lr] Data última revisão:
171108
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170318
[St] Status:MEDLINE
[do] DOI:10.1007/s00497-017-0300-7


  5 / 543 MEDLINE  
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[PMID]:28063585
[Au] Autor:Lepot L; Vanden Driessche T; Lunstroot K; Barret A; Gason F; De Wael K
[Ad] Endereço:National Institute of Criminalistics and Criminology (NICC-INCC), Chaussée de Vilvorde 100, B-1120 Brussels, Belgium. Electronic address: Laurent.Lepot@just.fgov.be.
[Ti] Título:Extraneous fibre traces brought by river water - A case study.
[So] Source:Sci Justice;57(1):53-57, 2017 Jan.
[Is] ISSN:1355-0306
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:The fibre traces on a young victim found underwater were mostly single fibre traces besides small amounts of fibre collectives indistinguishable from his parents clothes (mainly wool). Most of those single fibre traces were blue-grey polyester fibres showing tiny differences among each other. They were unexpected according to known population fibre studies. One year after the victim's discovery experiments were conducted to evaluate the possible contamination with fibres from river water. A small amount of extraneous fibres were collected among which blue and grey-black cotton and man-made (mainly polyester) fibres. All man-made fibres were single fibre traces and small fibre collectives were only observed for cotton. These results confirmed the frequent occurrence of blue and grey-black cotton fibres as background, but also highlighted the possible contamination with single blue and grey-black man-made fibres from river water. No wool was found, strengthening the significance of the wool fibre collectives present on the victim.
[Mh] Termos MeSH primário: Vestuário
Rios
[Mh] Termos MeSH secundário: Ciências Forenses
Seres Humanos
Imersão
Masculino
Microespectrofotometria
Manejo de Espécimes
[Pt] Tipo de publicação:CASE REPORTS; JOURNAL ARTICLE
[Em] Mês de entrada:1706
[Cu] Atualização por classe:171024
[Lr] Data última revisão:
171024
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170109
[St] Status:MEDLINE


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[PMID]:27873005
[Au] Autor:Stavenga DG; Meglic A; Pirih P; Koshitaka H; Arikawa K; Wehling MF; Belusic G
[Ad] Endereço:Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, NL9747AG, Groningen, The Netherlands. D.G.Stavenga@rug.nl.
[Ti] Título:Photoreceptor spectral tuning by colorful, multilayered facet lenses in long-legged fly eyes (Dolichopodidae).
[So] Source:J Comp Physiol A Neuroethol Sens Neural Behav Physiol;203(1):23-33, 2017 Jan.
[Is] ISSN:1432-1351
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:The facet lenses of the compound eyes of long-legged flies (Dolichopodidae) feature a striking, interlaced coloration pattern, existing of alternating rows of green-yellow and orange-red reflecting facets, due to dielectric multilayers located distally in the facet lenses (Bernard and Miller. Invest Ophthalmol 7:416-434 (1968). We investigated this phenomenon in the dolichopodid Dolichopus nitidus by applying microspectrophotometry, electron microscopy and optical modeling. The measured narrow-band reflectance spectra, peaking at ~540 and ~590 nm with bandwidth ~105 nm, are well explained by a refractive index oscillating sinusoidally in six periods around a mean value of about 1.44 with amplitude 0.6. The facet lens reflectance spectra are associated with a spectrally restricted, reduced transmittance, which causes modified spectral sensitivities of the underlying photoreceptors. Based on the modeling and electroretinography of the dolichopodid Condylostylus japonicus we conjecture that the green and orange facets narrow the spectral bandwidths of blue and green central photoreceptors, respectively, thus possibly improving color and/or polarization vision.
[Mh] Termos MeSH primário: Olho Composto de Artrópodes/metabolismo
Olho Composto de Artrópodes/ultraestrutura
Dípteros/anatomia & histologia
Dípteros/metabolismo
Células Fotorreceptoras de Invertebrados/metabolismo
[Mh] Termos MeSH secundário: Animais
Eletrorretinografia
Feminino
Proteínas de Insetos/metabolismo
Iridescência
Masculino
Microscopia Eletrônica de Transmissão
Microespectrofotometria
Modelos Biológicos
Pigmentos da Retina/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Insect Proteins); 0 (Retinal Pigments)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170925
[Lr] Data última revisão:
170925
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161123
[St] Status:MEDLINE
[do] DOI:10.1007/s00359-016-1131-y


  7 / 543 MEDLINE  
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[PMID]:27820927
[Au] Autor:Liu DW; Lu Y; Yan HY; Zakon HH
[Ad] Endereço:Marine Research Station, Academia Sinica, Jiaoshi Township, Taiwan.
[Ti] Título:South American Weakly Electric Fish (Gymnotiformes) Are Long-Wavelength-Sensitive Cone Monochromats.
[So] Source:Brain Behav Evol;88(3-4):204-212, 2016.
[Is] ISSN:1421-9743
[Cp] País de publicação:Switzerland
[La] Idioma:eng
[Ab] Resumo:Losses of cone opsin genes are noted in animals that are nocturnal or rely on senses other than vision. We investigated the cone opsin repertoire of night-active South American weakly electric fish. We obtained opsin gene sequences from genomic DNA of 3 gymnotiforms (Eigenmannia virescens, Sternopygus macrurus, Apteronotus albifrons) and the assembled genome of the electric eel (Electrophorus electricus). We identified genes for long-wavelength-sensitive (LWS) and medium-wavelength-sensitive cone opsins (RH2) and rod opsins (RH1). Neither of the 2 short-wavelength-sensitive cone opsin genes were found and are presumed lost. The fact that Electrophorus has a complete repertoire of extraretinal opsin genes and conservation of synteny with the zebrafish (Danio rerio) for genes flanking the 2 short-wavelength-sensitive opsin genes supports the supposition of gene loss. With microspectrophotometry and electroretinograms we observed absorption spectra consistent with RH1 and LWS but not RH2 opsins in the retinal photoreceptors of E. virescens. This profile of opsin genes and their retinal expression is identical to the gymnotiform's sister group, the catfish, which are also nocturnally active and bear ampullary electroreceptors, suggesting that this pattern likely occurred in the common ancestor of gymnotiforms and catfish. Finally, we noted an unusual N-terminal motif lacking a conserved glycosylation consensus site in the RH2 opsin of gymnotiforms, a catfish and a characin (Astyanax mexicanus). Mutations at this site influence rhodopsin trafficking in mammalian photoreceptors and cause retinitis pigmentosa. We speculate that this unusual N terminus may be related to the absence of the RH2 opsin in the cones of gymnotiforms and catfish.
[Mh] Termos MeSH primário: Opsinas dos Cones/genética
Expressão Gênica/fisiologia
Gimnotiformes/fisiologia
Células Fotorreceptoras Retinianas Cones/fisiologia
[Mh] Termos MeSH secundário: Animais
Electrophorus/genética
Electrophorus/fisiologia
Eletrorretinografia
Expressão Gênica/genética
Genoma
Gimnotiformes/genética
Microespectrofotometria
América do Sul
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Cone Opsins)
[Em] Mês de entrada:1707
[Cu] Atualização por classe:170719
[Lr] Data última revisão:
170719
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161108
[St] Status:MEDLINE
[do] DOI:10.1159/000450746


  8 / 543 MEDLINE  
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[PMID]:27553281
[Au] Autor:Liu Z; Tang Y; Chen F; Liu X; Liu Z; Zhong J; Hu J; Lü J
[Ad] Endereço:Division of Physical Biology and CAS Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences (CAS), Shanghai 201800, China; University of Chinese Academy of Science, Beijing 100049, China.
[Ti] Título:Synchrotron FTIR microspectroscopy reveals early adipogenic differentiation of human mesenchymal stem cells at single-cell level.
[So] Source:Biochem Biophys Res Commun;478(3):1286-91, 2016 09 23.
[Is] ISSN:1090-2104
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Human mesenchymal stem cells (hMSCs) have been used as an ideal in vitro model to study human adipogenesis. However, little knowledge of the early stage differentiation greatly hinders our understanding on the mechanism of the adipogenesis processes. In this study, synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy was applied to track the global structural and compositional changes of lipids, proteins and nucleic acids inside individual hMSCs along the time course. The multivariate analysis of the SR-FTIR spectra distinguished the dynamic and significant changes of the lipids and nucleic acid at early differentiation stage. Importantly, changes of lipid structure during early days (Day 1-3) of differentiation might serve as a potential biomarker in identifying the state in early differentiation at single cell level. These results proved that SR-FTIR is a powerful tool to study the stem cell fate determination and early lipogenesis events.
[Mh] Termos MeSH primário: Adipogenia
Diferenciação Celular
Células Mesenquimais Estromais/citologia
Microespectrofotometria
Análise de Célula Única/métodos
Espectroscopia de Infravermelho com Transformada de Fourier
Síncrotrons
[Mh] Termos MeSH secundário: Adipócitos/citologia
Biomarcadores/análise
Células Cultivadas
Seres Humanos
Lipídeos/análise
Ácidos Nucleicos/análise
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Biomarkers); 0 (Lipids); 0 (Nucleic Acids)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:171127
[Lr] Data última revisão:
171127
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160825
[St] Status:MEDLINE


  9 / 543 MEDLINE  
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[PMID]:27374557
[Au] Autor:Chen JB; Sun SQ; Zhou Q
[Ad] Endereço:Department of Chemistry, Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Tsinghua University, Beijing 100084, China.
[Ti] Título:Chemical morphology of Areca nut characterized directly by Fourier transform near-infrared and mid-infrared microspectroscopic imaging in reflection modes.
[So] Source:Food Chem;212:469-75, 2016 Dec 01.
[Is] ISSN:0308-8146
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Fourier transform near-infrared (NIR) and mid-infrared (MIR) imaging techniques are essential tools to characterize the chemical morphology of plant. The transmission imaging mode is mostly used to obtain easy-to-interpret spectra with high signal-to-noise ratio. However, the native chemical compositions and physical structures of plant samples may be altered when they are microtomed for the transmission tests. For the direct characterization of thick plant samples, the combination of the reflection NIR imaging and the attenuated total reflection (ATR) MIR imaging is proposed in this research. First, the reflection NIR imaging method can explore the whole sample quickly to find out typical regions in small sizes. Next, each small typical region can be measured by the ATR-MIR imaging method to reveal the molecular structures and spatial distributions of compounds of interest. As an example, the chemical morphology of Areca nut section is characterized directly by the above approach.
[Mh] Termos MeSH primário: Areca/química
Nozes/química
Extratos Vegetais/análise
Espectroscopia de Luz Próxima ao Infravermelho/métodos
[Mh] Termos MeSH secundário: Análise de Fourier
Microespectrofotometria/métodos
Estrutura Molecular
Razão Sinal-Ruído
Espectroscopia de Infravermelho com Transformada de Fourier/métodos
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Plant Extracts)
[Em] Mês de entrada:1701
[Cu] Atualização por classe:170119
[Lr] Data última revisão:
170119
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160705
[St] Status:MEDLINE


  10 / 543 MEDLINE  
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[PMID]:27358455
[Au] Autor:Berry J; Frederiksen R; Yao Y; Nymark S; Chen J; Cornwall C
[Ad] Endereço:Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118.
[Ti] Título:Effect of Rhodopsin Phosphorylation on Dark Adaptation in Mouse Rods.
[So] Source:J Neurosci;36(26):6973-87, 2016 Jun 29.
[Is] ISSN:1529-2401
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:UNLABELLED: Rhodopsin is a prototypical G-protein-coupled receptor (GPCR) that is activated when its 11-cis-retinal moiety is photoisomerized to all-trans retinal. This step initiates a cascade of reactions by which rods signal changes in light intensity. Like other GPCRs, rhodopsin is deactivated through receptor phosphorylation and arrestin binding. Full recovery of receptor sensitivity is then achieved when rhodopsin is regenerated through a series of steps that return the receptor to its ground state. Here, we show that dephosphorylation of the opsin moiety of rhodopsin is an extremely slow but requisite step in the restoration of the visual pigment to its ground state. We make use of a novel observation: isolated mouse retinae kept in standard media for routine physiologic recordings display blunted dephosphorylation of rhodopsin. Isoelectric focusing followed by Western blot analysis of bleached isolated retinae showed little dephosphorylation of rhodopsin for up to 4 h in darkness, even under conditions when rhodopsin was completely regenerated. Microspectrophotometeric determinations of rhodopsin spectra show that regenerated phospho-rhodopsin has the same molecular photosensitivity as unphosphorylated rhodopsin and that flash responses measured by trans-retinal electroretinogram or single-cell suction electrode recording displayed dark-adapted kinetics. Single quantal responses displayed normal dark-adapted kinetics, but rods were only half as sensitive as those containing exclusively unphosphorylated rhodopsin. We propose a model in which light-exposed retinae contain a mixed population of phosphorylated and unphosphorylated rhodopsin. Moreover, complete dark adaptation can only occur when all rhodopsin has been dephosphorylated, a process that requires >3 h in complete darkness. SIGNIFICANCE STATEMENT: G-protein-coupled receptors (GPCRs) constitute the largest superfamily of proteins that compose ∼4% of the mammalian genome whose members share a common membrane topology. Signaling by GPCRs regulate a wide variety of physiological processes, including taste, smell, hearing, vision, and cardiovascular, endocrine, and reproductive homeostasis. An important feature of GPCR signaling is its timely termination. This normally occurs when, after their activation, GPCRs are rapidly phosphorylated by specific receptor kinases and subsequently bound by cognate arrestins. Recovery of receptor sensitivity to the ground state then requires dephosphorylation of the receptor and unbinding of arrestin, processes that are poorly understood. Here we investigate in mouse rod photoreceptors the relationship between rhodopsin dephosphorylation and recovery of visual sensitivity.
[Mh] Termos MeSH primário: Adaptação à Escuridão/genética
Células Fotorreceptoras Retinianas Bastonetes/fisiologia
Rodopsina/metabolismo
[Mh] Termos MeSH secundário: Animais
Biofísica
Adaptação à Escuridão/efeitos dos fármacos
Eletrorretinografia
Receptor Quinase 1 Acoplada a Proteína G/genética
Receptor Quinase 1 Acoplada a Proteína G/metabolismo
Proteínas Heterotriméricas de Ligação ao GTP/genética
Proteínas Heterotriméricas de Ligação ao GTP/metabolismo
Técnicas In Vitro
Focalização Isoelétrica
Luz
Camundongos
Camundongos Endogâmicos C57BL
Camundongos Transgênicos
Microespectrofotometria
Mutação/genética
Opsinas/metabolismo
Fosforilação/efeitos dos fármacos
Fosforilação/genética
Retina/citologia
Retina/efeitos dos fármacos
Retinaldeído/farmacologia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Gnat2 protein, mouse); 0 (Opsins); 9009-81-8 (Rhodopsin); EC 2.7.11.14 (G-Protein-Coupled Receptor Kinase 1); EC 3.6.5.1 (Heterotrimeric GTP-Binding Proteins); RR725D715M (Retinaldehyde)
[Em] Mês de entrada:1707
[Cu] Atualização por classe:170713
[Lr] Data última revisão:
170713
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160701
[St] Status:MEDLINE
[do] DOI:10.1523/JNEUROSCI.3544-15.2016



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