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https://www.readbyqxmd.com/read/28645515/adaptations-in-rod-outer-segment-disc-membranes-in-response-to-environmental-lighting-conditions
#1
Tatini Rakshit, Subhadip Senapati, Vipul M Parmar, Bhubanananda Sahu, Akiko Maeda, Paul S H Park
The light-sensing rod photoreceptor cell exhibits several adaptations in response to the lighting environment. While adaptations to short-term changes in lighting conditions have been examined in depth, adaptations to long-term changes in lighting conditions are less understood. Atomic force microscopy was used to characterize the structure of rod outer segment disc membranes, the site of photon absorption by the pigment rhodopsin, to better understand how photoreceptor cells respond to long-term lighting changes...
June 20, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28644485/probing-the-early-stages-of-photoreception-in-photoactive-yellow-protein-with-ultrafast-time-domain-raman-spectroscopy
#2
Hikaru Kuramochi, Satoshi Takeuchi, Kento Yonezawa, Hironari Kamikubo, Mikio Kataoka, Tahei Tahara
Unveiling the nuclear motions of photoreceptor proteins in action is a crucial goal in protein science in order to understand their elaborate mechanisms and how they achieve optimal selectivity and efficiency. Previous studies have provided detailed information on the structures of intermediates that appear during the later stages (>ns) of such photoreception cycles, yet the initial events immediately after photoabsorption remain unclear because of experimental challenges in monitoring nuclear rearrangements on ultrafast timescales, including protein-specific low-frequency motions...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28643368/cell-lineage-tracing-in-the-retina-could-material-transfer-distort-conclusions
#3
Camille Boudreau-Pinsonneault, Michel Cayouette
Recent studies reported the transfer of fluorescent labels between grafted and host cells after transplantation of photoreceptor precursor cells in the mouse retina. While clearly impacting the interpretation of transplantation studies in the retina, the potential impact of material transfer in other experimental paradigms using cell-specific labels remains uncertain. Here, we briefly review the evidence supporting material transfer in transplantation studies and discuss whether it might influence retinal cell lineage tracing experiments in developmental and regeneration studies...
June 23, 2017: Developmental Dynamics: An Official Publication of the American Association of Anatomists
https://www.readbyqxmd.com/read/28641882/ferredoxin-dependent-bilin-reductases-in-eukaryotic-algae-ubiquity-and-diversity
#4
Nathan C Rockwell, J Clark Lagarias
Linear tetrapyrroles (bilins) are produced from heme by heme oxygenase, usually forming biliverdin IXα (BV). Fungi and bacteria use BV as chromophore for phytochrome photoreceptors. Oxygenic photosynthetic organisms use BV as a substrate for ferredoxin-dependent bilin reductases (FDBRs), enzymes that produce diverse reduced bilins used as light-harvesting pigments in phycobiliproteins and as photoactive photoreceptor chromophores. Bilin biosynthesis is essential for phototrophic growth in Chlamydomonas reinhardtii despite the absence of phytochromes or phycobiliproteins in this organism, raising the possibility that bilins are more generally required for phototrophic growth by algae...
May 31, 2017: Journal of Plant Physiology
https://www.readbyqxmd.com/read/28640837/identification-and-prediction-of-alternative-transcription-start-sites-that-generate-rod-photoreceptor-specific-transcripts-from-ubiquitously-expressed-genes
#5
Evgenya Y Popova, Anna C Salzberg, Chen Yang, Samuel Shao-Min Zhang, Colin J Barnstable
Transcriptome complexity is substantially increased by the use of multiple transcription start sites for a given gene. By utilizing a rod photoreceptor-specific chromatin signature, and the RefSeq database of established transcription start sites, we have identified essentially all known rod photoreceptor genes as well as a group of novel genes that have a high probability of being expressed in rod photoreceptors. Approximately half of these novel rod genes are transcribed into multiple mRNA and/or protein isoforms through alternative transcriptional start sites (ATSS), only one of which has a rod-specific epigenetic signature and gives rise to a rod transcript...
2017: PloS One
https://www.readbyqxmd.com/read/28640147/human-photoreceptor-cone-density-measured-with-adaptive-optics-technology-rtx1-device-in-healthy-eyes-standardization-of-measurements
#6
Anna Zaleska-Żmijewska, Zbigniew M Wawrzyniak, Magdalena Ulińska, Jerzy Szaflik, Anna Dąbrowska, Jacek P Szaflik
The anatomic structures of the anterior segment of the eye enable correct reception of stimuli by the retina, which contains receptors that receive light impulses and transmit them to the visual cortex. The aim of this study was to assess the effect of the size of the sampling window in an adaptive optics (AO) flood-illumination retinal camera (rtx1) on cone density measurements in the eyes of healthy individuals and to investigate the differences in cone density and spacing in different quadrants of the retina...
June 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28639324/a-retina-like-dual-band-organic-photosensor-array-for-filter-free-near-infrared-to-memory-operations
#7
Hanlin Wang, Hongtao Liu, Qiang Zhao, Zhenjie Ni, Ye Zou, Jie Yang, Lifeng Wang, Yanqiu Sun, Yunlong Guo, Wenping Hu, Yunqi Liu
Human eyes use retina photoreceptor cells to absorb and distinguish photons from different wavelengths to construct an image. Mimicry of such a process and extension of its spectral response into the near-infrared (NIR) is indispensable for night surveillance, retinal prosthetics, and medical imaging applications. Currently, NIR organic photosensors demand optical filters to reduce visible interference, thus making filter-free and anti-visible NIR imaging a challenging task. To solve this limitation, a filter-free and conformal, retina-inspired NIR organic photosensor is presented...
June 22, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28637860/higher-order-neural-processing-tunes-motion-neurons-to-visual-ecology-in-three-species-of-hawkmoths
#8
A L Stöckl, D O'Carroll, E J Warrant
To sample information optimally, sensory systems must adapt to the ecological demands of each animal species. These adaptations can occur peripherally, in the anatomical structures of sensory organs and their receptors; and centrally, as higher-order neural processing in the brain. While a rich body of investigations has focused on peripheral adaptations, our understanding is sparse when it comes to central mechanisms. We quantified how peripheral adaptations in the eyes, and central adaptations in the wide-field motion vision system, set the trade-off between resolution and sensitivity in three species of hawkmoths active at very different light levels: nocturnal Deilephila elpenor, crepuscular Manduca sexta, and diurnal Macroglossum stellatarum...
June 28, 2017: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/28636933/drosophila-neuropeptide-f-signaling-independently-regulates-feeding-and-sleep-wake-behavior
#9
Brian Y Chung, Jennifer Ro, Sabine A Hutter, Kylie M Miller, Lakshmi S Guduguntla, Shu Kondo, Scott D Pletcher
Proper regulation of sleep-wake behavior and feeding is essential for organismal health and survival. While previous studies have isolated discrete neural loci and substrates important for either sleep or feeding, how the brain is organized to coordinate both processes with respect to one another remains poorly understood. Here, we provide evidence that the Drosophila Neuropeptide F (NPF) network forms a critical component of both adult sleep and feeding regulation. Activation of NPF signaling in the brain promotes wakefulness and adult feeding, likely through its cognate receptor NPFR...
June 20, 2017: Cell Reports
https://www.readbyqxmd.com/read/28636682/excited-state-characterization-of-carbonyl-containing-carotenoids-a-comparison-between-single-and-multireference-descriptions
#10
Riccardo Spezia, Stefan Knecht, Benedetta Mennucci
Carotenoids can play multiple roles in biological photoreceptors thanks to their rich photophysics. In the present work, we have investigated six of the most common carbonyl containing carotenoids: echinenone, canthaxanthin, astaxanthin, fucoxanthin, capsanthin and capsorubin. Their excitation properties are investigated by means of a hybrid density functional theory (DFT) and multireference configuration interaction (MRCI) approach to elucidate the role of the carbonyl group: the bright transition is of ππ* character, as expected, but the presence of a C[double bond, length as m-dash]O moiety reduces the energy of nπ* transitions which may become closer to the ππ* transition, in particular as the conjugation chain decreases...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28636018/fluorescence-lifetime-microscopy-reveals-the-biologically-related-photophysical-heterogeneity-of-oxyblepharismin-in-light-adapted-blue-blepharisma-japonicum-cells
#11
G Checcucci, B Storti, F Ghetti, G Signore, R Bizzarri
The step-up photophobic response of the heterotrich ciliate Blepharisma japonicum is mediated by a hypericinic pigment, blepharismin, which is not present in any of the known six families of photoreceptors, namely rhodopsins, phytochromes, xanthopsins, cryptochromes, phototropins, and BLUF proteins. Upon irradiation, native cells become light-adapted (blue) by converting blepharismin into the photochemically stable oxyblepharismin (OxyBP). So far, OxyBP has been investigated mainly from a photophysical point of view in vitro, either alone or complexed with proteins...
June 21, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28635593/the-protein-slr1143-is-an-active-diguanylate-cyclase-in-synechocystis-sp-pcc-6803-and-interacts-with-the-photoreceptor-cph2
#12
Veronika Angerer, Philipp Schwenk, Thomas Wallner, Volkhard Kaever, Andreas Hiltbrunner, Annegret Wilde
Cyclic-di-GMP is an ubiquitous second messenger in bacteria. Several c-di-GMP receptor proteins have been identified to date, and downstream signalling pathways are often mediated through protein-protein interactions. The photoreceptor Cph2 from the cyanobacterium Synechocystis sp. PCC 6803 comprises three domains related to c-di-GMP metabolism: two GGDEF and one EAL domain. It has been shown that the C-terminal GGDEF domain acts as blue-light triggered c-di-GMP producer thereby inhibiting motility of the cells in blue light...
June 21, 2017: Microbiology
https://www.readbyqxmd.com/read/28634860/molecular-chaperone-hsp70-and-its-constitutively-active-form-hsc70-play-an-indispensable-role-during-eye-development-of-drosophila-melanogaster
#13
Ajay Kumar, Anand K Tiwari
In the present study, we demonstrate that molecular chaperone Hsp70 and Hsc70 is essential for normal organization and development of ommatidial cells in Drosophila melanogaster eye. An exogenously expressed dominant negative mutant of Hsp70 (K71E) and Hsc70.4 (K71S and D206S) in an eye-specific manner resulted in eye degeneration that includes loss of eye pigment, disorganized ommatidia, abnormality in bristle cell arrangement and reduction in the eye size. The developmental organization of ommatidial cells (cone, photoreceptor, pigment, and bristle cell complex) was disturbed in Hsp70 and Hsc70 mutants...
June 20, 2017: Molecular Neurobiology
https://www.readbyqxmd.com/read/28634231/hyperactivity-of-the-arabidopsis-cryptochrome-cry1-l407f-mutant-is-caused-by-a-structural-alteration-close-to-the-cry1-atp-binding-sit
#14
Christian Orth, Nils Niemann, Lars Hennig, Lars-Oliver Essen, Alfred Batschauer
Plant cryptochromes (cry) act as UV-A/blue light receptors. The prototype, Arabidopsis thaliana cry1, regulates several light responses during the life cycle, including de-etiolation, and is also involved in regulating flowering time. The cry1 photocycle is initiated by light absorption by its FAD chromophore, which is most likely fully oxidized (FADox) in the dark state and photoreduced to the neutral flavin semiquinone (FADH(o)) in its lit state. Cryptochromes lack the DNA-repair activity of the closely related DNA photolyases, but retain the ability to bind nucleotides such as ATP...
June 20, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28633154/localized-bilateral-juxtafoveal-photoreceptor-loss-in-poems-a-new-association
#15
Christopher K Hwang, Anton M Kolomeyer, Alexander J Brucker, Jessica I W Morgan, Charles W Nichols, Tomas S Aleman
No abstract text is available yet for this article.
July 2017: Retina
https://www.readbyqxmd.com/read/28633009/rna-interference-reveals-the-coregulatory-effects-of-cylindromatosis-on-apoptosis-and-necroptosis-of-photoreceptor-cells-in-experimental-retinal-detachment
#16
Kai Dong, Linfeng Han, Jingwen Liu, Fenghua Wang, Xiaodong Sun
Inhibiting only cell apoptosis or necroptosis in photoreceptor cells does not protect them against death after traumatic retinal detachment. This study was designed to evaluate the coregulatory effects of the deubiquitinating enzyme cylindromatosis on the apoptosis and necroptosis of photoreceptor cells in experimental retinal detachment. Lentivirus Cyld shRNA was generated and used to suppress cylindromatosis expression in Sprague-Dawley rats. Three weeks after injection of lentivirus Cyld shRNA, retinal detachment surgery was performed...
June 17, 2017: American Journal of Pathology
https://www.readbyqxmd.com/read/28632879/reliability-and-agreement-between-metrics-of-cone-spacing-in-adaptive-optics-images-of-the-human-retinal-photoreceptor-mosaic
#17
Daniela Giannini, Giuseppe Lombardo, Letizia Mariotti, Nicholas Devaney, Sebastiano Serrao, Marco Lombardo
Purpose: To assess reliability and agreement among three metrics used to evaluate the distribution of cell distances in adaptive optics (AO) images of the cone mosaic. Methods: Using an AO flood illumination retinal camera, we acquired images of the cone mosaic in 20 healthy subjects and 12 patients with retinal diseases. The three spacing metrics studied were the center-to-center spacing (Scc), the local cone spacing (LCS), and the density recovery profile distance (DRPD)...
June 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28632846/suppression-of-hsp27-restores-retinal-function-and-protects-photoreceptors-from-apoptosis-in-a-light-induced-retinal-degeneration-animal-model
#18
Chih-Cheng Chien, Chi-Jung Huang, Lu-Tai Tien, Yu-Che Cheng, Chia-Ying Ke, Yih-Jing Lee
Purpose: We used a light-induced retinal degeneration animal model to investigate possible roles of heat shock protein 27 (HSP27) in retinal/photoreceptor protection. Methods: Sprague-Dawley rats were used for the light-induced retinal degeneration animal model. The histology of eye sections was observed for morphologic changes in the retina. Cell apoptosis was examined in each group using the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, and electroretinography was used to evaluate retinal function...
June 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28632317/qm-mm-study-on-the-photoreactions-of-dark-and-light-adapted-states-of-a-blue-light-ytva-lov-photoreceptor
#19
Xue-Ping Chang, Yuan-Jun Gao, Wei-Hai Fang, Ganglong Cui, Walter Thiel
The dark- and light-adapted states of YtvA LOV domains exhibit distinct excited-state behavior. We have employed high-level QM(MS-CASPT2)/MM calculations to study the photochemical reactions of the dark- and light-adapted states. The photoreaction from the dark-adapted state starts with an S1→T1 intersystem crossing followed by a triplet-state hydrogen transfer from the thiol to the flavin moiety that produces a diradical intermediate, and a subsequent internal conversion that triggers a barrierless C-S bond formation in the S0 state...
June 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28632034/recombinant-human-nerve-growth-factor-treatment-promotes-photoreceptor-survival-in-the-retinas-of-rats-with-retinitis-pigmentosa
#20
Marta Sacchetti, Flavio Mantelli, Maria Luisa Rocco, Alessandra Micera, Laura Brandolini, Laura Focareta, Claudio Pisano, Luigi Aloe, Alessandro Lambiase
PURPOSE: Increasing evidence suggests that nerve growth factor (NGF) exerts protective effects against retinal degeneration in animal models of retinitis pigmentosa (RP). This study aims at investigating the effects of intravitreal injection of recombinant human NGF (rhNGF) on retinal photoreceptors apoptosis in an animal model of RP, the Royal College of Surgeons (RCS) rats. METHODS: Thirty-six RCS rats were treated with intravitreal injection of rhNGF or murine NGF (mNGF) or vehicle at 20 postnatal days (pd) and sacrificed at 40 pd...
March 1, 2017: Current Eye Research
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