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Photoreceptors

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https://www.readbyqxmd.com/read/28091887/the-morphology-of-human-rod-ergs-obtained-by-silent-substitution-stimulation
#1
J Maguire, N R A Parry, J Kremers, I J Murray, D McKeefry
PURPOSE: To record transient ERGs from the light-adapted human retina using silent substitution stimuli which selectively reflect the activity of rod photoreceptors. We aim to describe the morphology of these waveforms and examine how they are affected by the use of less selective stimuli and by retinal pathology. METHODS: Rod-isolating stimuli with square-wave temporal profiles (250/250 ms onset/offset) were presented using a 4 primary LED ganzfeld stimulator...
January 13, 2017: Documenta Ophthalmologica. Advances in Ophthalmology
https://www.readbyqxmd.com/read/28089909/immunosuppression-via-loss-of-il2r%C3%AE-enhances-long-term-functional-integration-of-hesc-derived-photoreceptors-in-the-mouse-retina
#2
Jie Zhu, Helen Cifuentes, Joseph Reynolds, Deepak A Lamba
Loss of photoreceptors is a common endpoint in degenerative retinal diseases. Human pluripotent stem cells provide a potential source for photoreceptor replacement, but, even in mouse models, the efficiency and efficacy of transplantation-based repair remains poor. In this study, we examined the degree to which immune rejection contributes to these disappointing outcomes using an immunodeficient IL2 receptor γ (IL2rγ)-null mouse model. Our results show that prevention of cell rejection in the normal and degenerating retinal environment significantly improves long-term survival and integration of hESC-derived donor retinal cells...
December 29, 2016: Cell Stem Cell
https://www.readbyqxmd.com/read/28089219/prognostic-factors-of-epiretinal-membranes-a-systematic-review
#3
REVIEW
A I M Miguel, A Legris
INTRODUCTION: Epiretinal membranes (ERM) have been increasingly characterized with the advent of new optical coherence tomographies (OCTs). We intended to perform a systematic review regarding prognostic factors (PF) of ERM after surgery. MATERIALS AND METHODS: Systematic review of electronic databases was performed (last date of search was 10 August 2015): Medline, Scopus, Google Scholar, clinicaltrials.gov and current controlled trials. Search queries included: "membrane", "pucker", "prognosis", "prognostic", "epiretinal", "épirétinienne"...
January 11, 2017: Journal Français D'ophtalmologie
https://www.readbyqxmd.com/read/28088625/absence-of-dj-1-causes-age-related-retinal-abnormalities-in-association-with-increased-oxidative-stress
#4
Vera L Bonilha, Brent A Bell, Mary E Rayborn, Ivy S Samuels, Anna King, Joe G Hollyfield, Chengsong Xie, Huaibin Cai
Oxidative stress alters physiological function in most biological tissues and can lead to cell death. In the retina, oxidative stress initiates a cascade of events leading to focal loss of RPE and photoreceptors, which is thought to be a major contributing factor to geographic atrophy. Despite these implications, the molecular regulation of RPE oxidative stress under normal and pathological conditions remains largely unknown. A better understanding of the mechanisms involved in regulating RPE and photoreceptors oxidative stress response is greatly needed...
January 11, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28087932/the-complexity-of-fungal-vision
#5
Reinhard Fischer, Jesus Aguirre, Alfredo Herrera-Estrella, Luis M Corrochano
Life, as we know it, would not be possible without light. Light is not only a primary source of energy, but also an important source of information for many organisms. To sense light, only a few photoreceptor systems have developed during evolution. They are all based on an organic molecule with conjugated double bonds that allows energy transfer from visible (or UV) light to its cognate protein to translate the primary physical photoresponse to cell-biological actions. The three main classes of receptors are flavin-based blue-light, retinal-based green-light (such as rhodopsin), and linear tetrapyrrole-based red-light sensors...
December 2016: Microbiology Spectrum
https://www.readbyqxmd.com/read/28087896/eag-channels-expressed-in-microvillar-photoreceptors-are-unsuited-to-diurnal-vision
#6
Esa-Ville Immonen, Andrew S French, Päivi H Torkkeli, Hongxia Liu, Mikko Vähäsöyrinki, Roman V Frolov
The principles underlying evolutionary selection of ion channels for expression in sensory neurons are unclear. Among species possessing microvillar photoreceptors the major ionic conductances have only been identified in Drosophila melanogaster. In Drosophila depolarization is provided by light-activated TRP channels with a minor contribution from TRPL channels, while repolarization is mediated by sustained voltage-gated K(+) (Kv) channels of the Shab family. Bright light stimulates Shab channels, further restricting depolarization and improving membrane bandwidth...
January 13, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28080904/photoreceptor-degeneration-in-a-mountain-lion-cub-puma-concolor
#7
Andrew R DiSalvo, Christopher M Reilly, K Tomo Wiggans, Leslie W Woods, Ray F Wack, Deana L Clifford
An orphaned 4-mo-old female mountain lion cub ( Puma concolor ) was captured along the coastline in Montaña de Oro State Park in Los Osos, California, USA. Following suspicion that the cub was visually impaired, ophthalmic examination revealed diffuse bilateral retinal atrophy. Due to a poor prognosis, humane euthanasia was elected. Necropsy and histopathological findings were consistent with photoreceptor degeneration. Based on the cub's signalment, history, and histopathology, a genetic or nutritional etiology was suspected, with the former etiology more strongly supported...
December 2016: Journal of Zoo and Wildlife Medicine: Official Publication of the American Association of Zoo Veterinarians
https://www.readbyqxmd.com/read/28076806/measurement-of-slow-spontaneous-release-of%C3%A2-11-cis-retinal-from-rhodopsin
#8
He Tian, Thomas P Sakmar, Thomas Huber
The vertebrate visual photoreceptor rhodopsin (Rho) is a unique G protein-coupled receptor as it utilizes a covalently tethered inverse agonist (11-cis-retinal) as the native ligand. Previously, electrophysiological studies showed that ligand binding of 11-cis-retinal in dark-adapted Rho was essentially irreversible with a half-life estimated to be 420 years, until after thermal isomerization to all-trans-retinal, which then slowly dissociates. This long lifetime of 11-cis-retinal binding was considered to be physiologically important for minimizing background signal (dark noise) of the visual system...
January 10, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28076757/ipsc-derived-retina-transplants-improve-vision-in-rd1-end-stage-retinal-degeneration-mice
#9
Michiko Mandai, Momo Fujii, Tomoyo Hashiguchi, Genshiro A Sunagawa, Shinichiro Ito, Jianan Sun, Jun Kaneko, Junki Sho, Chikako Yamada, Masayo Takahashi
Recent success in functional recovery by photoreceptor precursor transplantation in dysfunctional retina has led to an increased interest in using embryonic stem cell (ESC) or induced pluripotent stem cell (iPSC)-derived retinal progenitors to treat retinal degeneration. However, cell-based therapies for end-stage degenerative retinas that have lost the outer nuclear layer (ONL) are still a big challenge. In the present study, by transplanting mouse iPSC-derived retinal tissue (miPSC retina) in the end-stage retinal-degeneration model (rd1), we visualized the direct contact between host bipolar cell terminals and the presynaptic terminal of graft photoreceptors by gene labeling, showed light-responsive behaviors in transplanted rd1 mice, and recorded responses from the host retina with transplants by ex vivo micro-electroretinography and ganglion cell recordings using a multiple-electrode array system...
January 10, 2017: Stem Cell Reports
https://www.readbyqxmd.com/read/28076391/assessing-sexual-dicromatism-the-importance-of-proper-parameterization-in-tetrachromatic-visual-models
#10
Pierre-Paul Bitton, Kevyn Janisse, Stéphanie M Doucet
Perceptual models of animal vision have greatly contributed to our understanding of animal-animal and plant-animal communication. The receptor-noise model of color contrasts has been central to this research as it quantifies the difference between two colors for any visual system of interest. However, if the properties of the visual system are unknown, assumptions regarding parameter values must be made, generally with unknown consequences. In this study, we conduct a sensitivity analysis of the receptor-noise model using avian visual system parameters to systematically investigate the influence of variation in light environment, photoreceptor sensitivities, photoreceptor densities, and light transmission properties of the ocular media and the oil droplets...
2017: PloS One
https://www.readbyqxmd.com/read/28074469/development-of-cone-photoreceptors-and-their-synapses-in-the-human-and-monkey-fovea
#11
Anita Hendrickson, Chi Zhang
During retinal development, ribbon synapse assembly in the photoreceptors is a crucial step involving numerous molecules. While the developmental sequence of plexiform layers in human retina has been characterized, the molecular steps of synaptogenesis remain largely unknown. In the present study, we focused on the central rod-free region of primate retina, the fovea, to specifically investigate the development of cone photoreceptor ribbon synapses. Immunocytochemistry and electron microscopy were utilized to track the expression of photoreceptor transduction proteins and ribbon and synaptic markers in fetal human and Macaca retina...
January 11, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28068562/epigenetic-histopathological-and-transcriptomic-effects-following-exposure-to-depleted-uranium-in-adult-zebrafish-and-their-progeny
#12
Kewin Gombeau, Jean-Paul Bourdineaud, Jean-Luc Ravanat, Olivier Armant, Virginie Camilleri, Isabelle Cavalie, Magali Floriani, Christelle Adam-Guillermin
This study investigated the effects of adult zebrafish exposure to a nominal concentration of 20μgL(-1) of depleted uranium (DU) for six days upon DNA methylation, gene expression and the appearance of histopathological damage in their progeny. In the embryos at the 2-8 cell stage, the parental exposure induced significant DU accumulation, with levels seven times higher than those measured in the control embryos, but in larvae 96h post-fertilisation (hpf), uranium concentration had already returned to a level identical to that of the control larvae...
December 8, 2016: Aquatic Toxicology
https://www.readbyqxmd.com/read/28068435/adaptive-optics-reveals-photoreceptor-abnormalities-in-diabetic-macular-ischemia
#13
Peter L Nesper, Fabio Scarinci, Amani A Fawzi
Diabetic macular ischemia (DMI) is a phenotype of diabetic retinopathy (DR) associated with chronic hypoxia of retinal tissue. The goal of this prospective observational study was to report evidence of photoreceptor abnormalities using adaptive optics scanning laser ophthalmoscopy (AOSLO) in eyes with DR in the setting of deep capillary plexus (DCP) non-perfusion. Eleven eyes from 11 patients (6 women, age 31-68), diagnosed with DR without macular edema, underwent optical coherence tomography angiography (OCTA) and AOSLO imaging...
2017: PloS One
https://www.readbyqxmd.com/read/28067410/the-photolyase-cryptochrome-family-of-proteins-as-dna-repair-enzymes-and-transcriptional-repressors
#14
REVIEW
Ibrahim Halil Kavakli, Ibrahim Baris, Mehmet Tardu, Şeref Gül, Haşimcan Öner, Sibel Çal, Selma Bulut, Darya Yarparvar, Çağlar Berkel, Pınar Ustaoğlu, Cihan Aydın
Light is a very important environmental factor that governs many cellular responses in organisms. As a consequence, organisms possess different kinds of light-sensing photoreceptors to regulate their physiological variables and adapt to a given habitat. The cryptochrome/photolyase family (CPF) includes photoreceptors that perform different functions in different organisms. Photolyases repair ultraviolet-induced DNA damage by a process known as photoreactivation using photons absorbed from the blue end of the light spectrum...
November 16, 2016: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28065882/rescue-of-mutant-rhodopsin-traffic-by-metformin-induced-ampk-activation-accelerates-photoreceptor-degeneration
#15
Dimitra Athanasiou, Monica Aguila, Chikwado A Opefi, Kieron South, James Bellingham, Dalila Bevilacqua, Peter M Munro, Naheed Kanuga, Francesca E Mackenzie, Adam M Dubis, Anastasios Georgiadis, Anna B Graca, Rachael A Pearson, Robin R Ali, Sanae Sakami, Krzysztof Palczewski, Michael Y Sherman, Philip J Reeves, Michael E Cheetham
Protein misfolding caused by inherited mutations leads to loss of protein function and potentially toxic 'gain of function', such as the dominant P23H rhodopsin mutation that causes retinitis pigmentosa (RP). Here, we tested whether the AMPK activator metformin could affect the P23H rhodopsin synthesis and folding. In cell models, metformin treatment improved P23H rhodopsin folding and traffic. In animal models of P23H RP, metformin treatment successfully enhanced P23H traffic to the rod outer segment, but this led to reduced photoreceptor function and increased photoreceptor cell death...
January 7, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28065589/perk-and-xbp1-differentially-regulate-cxcl10-and-ccl2-production
#16
Shuang Zhu, Hua Liu, Haibo Sha, Ling Qi, Dian-Shuai Gao, Wenbo Zhang
Inflammation plays a key role in the pathogenesis of many retinal degenerative diseases related with photoreceptor dysfunction/degeneration. However the involvement of photoreceptor cells in inflammatory reactions is largely unknown as they are not considered as inflammatory cells. In this study, we assessed whether photoreceptor cells can produce CCL2 and CXCL10, two important players in inflammation during endoplasmic reticulum (ER) stress. After photoreceptor 661 W cells were treated with ER stress inducer thapsigargin (TG), induction of ER stress increased CXCL10 and CCL2 expression at both mRNA and protein levels, which was significantly blocked by an ER stress blocker 4-phenylbutyrate...
January 5, 2017: Experimental Eye Research
https://www.readbyqxmd.com/read/28062690/cryptochrome-mediates-behavioral-executive-choice-in-response-to-uv-light
#17
Lisa S Baik, Keri J Fogle, Logan Roberts, Alexis M Galschiodt, Joshua A Chevez, Yocelyn Recinos, Vinh Nguy, Todd C Holmes
Drosophila melanogaster CRYPTOCHROME (CRY) mediates behavioral and electrophysiological responses to blue light coded by circadian and arousal neurons. However, spectroscopic and biochemical assays of heterologously expressed CRY suggest that CRY may mediate functional responses to UV-A (ultraviolet A) light as well. To determine the relative contributions of distinct phototransduction systems, we tested mutants lacking CRY and mutants with disrupted opsin-based phototransduction for behavioral and electrophysiological responses to UV light...
January 6, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28062565/the-biology-of-ciliary-dynamics
#18
Kuo-Shun Hsu, Jen-Zen Chuang, Ching-Hwa Sung
The cilium is an evolutionally conserved apical membrane protrusion that senses and transduces diverse signals to regulate a wide range of cellular activities. The cilium is dynamic in length, structure, and protein composition. Dysregulation of ciliary dynamics has been linked with ciliopathies and other human diseases. The cilium undergoes cell-cycle-dependent assembly and disassembly, with ciliary resorption linked with G1-S transition and cell-fate choice. In the resting cell, the cilium remains sensitive to environmental cues for remodeling during tissue homeostasis and repair...
January 6, 2017: Cold Spring Harbor Perspectives in Biology
https://www.readbyqxmd.com/read/28062154/phototransduction-early-steps-model-based-on-beer-lambert-optical-law
#19
Ezequiel M Salido, Leonardo N Servalli, Juan Carlos Gomez, Claudio Verrastro
The amount of available rhodopsin on the photoreceptor outer segment and its change over time is not considered in classic models of phototransduction. Thus, those models do not take into account the absorptance variation of the outer segment under different brightness conditions. The relationship between the light absorbed by a medium and its absorptance is well described by the Beer-Lambert law. This newly proposed model implements the absorptance variation phenomenon in a set of equations that admit photons per second as input and results in active rhodopsins per second as output...
January 13, 2017: Vision Research
https://www.readbyqxmd.com/read/28060904/past1-modulates-drosophila-eye-development
#20
Orly Dorot, Hermann Steller, Daniel Segal, Mia Horowitz
Endocytosis is a multi-step process involving a large number of proteins, both general factors, such as clathrin and adaptor protein complexes, and unique proteins, which modulate specialized endocytic processes, like the EHD proteins. EHDs are a family of Eps15 Homology Domain containing proteins that consists of four mammalian homologs, one C. elegans, one Drosophila melanogaster and two plants orthologs. These membrane-associated proteins are involved in different steps of endocytic trafficking pathways...
2017: PloS One
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