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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/28642345/evolution-of-nonspectral-rhodopsin-function-at-high-altitudes
#2
Gianni M Castiglione, Frances E Hauser, Brian S Liao, Nathan K Lujan, Alexander Van Nynatten, James M Morrow, Ryan K Schott, Nihar Bhattacharyya, Sarah Z Dungan, Belinda S W Chang
High-altitude environments present a range of biochemical and physiological challenges for organisms through decreases in oxygen, pressure, and temperature relative to lowland habitats. Protein-level adaptations to hypoxic high-altitude conditions have been identified in multiple terrestrial endotherms; however, comparable adaptations in aquatic ectotherms, such as fishes, have not been as extensively characterized. In enzyme proteins, cold adaptation is attained through functional trade-offs between stability and activity, often mediated by substitutions outside the active site...
June 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28636018/fluorescence-lifetime-microscopy-reveals-the-biologically-related-photophysical-heterogeneity-of-oxyblepharismin-in-light-adapted-blue-blepharisma-japonicum-cells
#3
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/28634470/the-dark-side-of-the-mushroom-spring-microbial-mat-life-in-the-shadow-of-chlorophototrophs-ii-metabolic-functions-of-abundant-community-members-predicted-from-metagenomic-analyses
#4
Vera Thiel, Michael Hügler, David M Ward, Donald A Bryant
Microbial mat communities in the effluent channels of Octopus and Mushroom Springs within the Lower Geyser Basin of Yellowstone National Park have been extensively characterized. Previous studies have focused on the chlorophototrophic organisms of the phyla Cyanobacteria and Chloroflexi. However, the diversity and metabolic functions of the other portion of the community in the microoxic/anoxic region of the mat are poorly understood. We recently described the diverse but extremely uneven microbial assemblage in the undermat of Mushroom Spring based on 16S rRNA amplicon sequences, which was dominated by Roseiflexus members, filamentous anoxygenic chlorophototrophs...
2017: Frontiers in Microbiology
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
#5
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/28632034/recombinant-human-nerve-growth-factor-treatment-promotes-photoreceptor-survival-in-the-retinas-of-rats-with-retinitis-pigmentosa
#6
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
https://www.readbyqxmd.com/read/28630812/molecular-properties-of-a-dtd-channelrhodopsin-from-guillardia-theta
#7
Yumeka Yamauchi, Masae Konno, Shota Ito, Satoshi P Tsunoda, Keiichi Inoue, Hideki Kandori
Microbial rhodopsins are membrane proteins found widely in archaea, eubacteria and eukaryotes (fungal and algal species). They have various functions, such as light-driven ion pumps, light-gated ion channels, light sensors and light-activated enzymes. A light-driven proton pump bacteriorhodopsin (BR) contains a DTD motif at positions 85, 89, and 96, which is unique to archaeal proton pumps. Recently, channelrhodopsins (ChRs) containing the DTD motif, whose sequential identity is ~20% similar to BR and to cation ChRs in Chlamydomonas reinhardtii (CrCCRs), were found...
2017: Biophysics and Physicobiology
https://www.readbyqxmd.com/read/28619647/using-crispr-cas9-to-generate-gene-corrected-autologous-ipscs-for-the-treatment-of-inherited-retinal-degeneration
#8
Erin R Burnight, Manav Gupta, Luke A Wiley, Kristin R Anfinson, Audrey Tran, Robinson Triboulet, Jeremy M Hoffmann, Darcey L Klaahsen, Jeaneen L Andorf, Chunhua Jiao, Elliott H Sohn, Malavika K Adur, Jason W Ross, Robert F Mullins, George Q Daley, Thorsten M Schlaeger, Edwin M Stone, Budd A Tucker
Patient-derived induced pluripotent stem cells (iPSCs) hold great promise for autologous cell replacement. However, for many inherited diseases, treatment will likely require genetic repair pre-transplantation. Genome editing technologies are useful for this application. The purpose of this study was to develop CRISPR-Cas9-mediated genome editing strategies to target and correct the three most common types of disease-causing variants in patient-derived iPSCs: (1) exonic, (2) deep intronic, and (3) dominant gain of function...
June 12, 2017: Molecular Therapy: the Journal of the American Society of Gene Therapy
https://www.readbyqxmd.com/read/28619035/an-evolutionary-optimization-of-a-rhodopsin-based-phototrophic-metabolism-in-escherichia-coli
#9
Hyun Aaron Kim, Hyun Ju Kim, Jihoon Park, Ah Reum Choi, Kyoo Heo, Haeyoung Jeong, Kwang-Hwan Jung, Yeong-Jae Seok, Pil Kim, Sang Jun Lee
BACKGROUND: The expression of the Gloeobacter rhodopsin (GR) in a chemotrophic Escherichia coli enables the light-driven phototrophic energy generation. Adaptive laboratory evolution has been used for acquiring desired phenotype of microbial cells and for the elucidation of basic mechanism of molecular evolution. To develop an optimized strain for the artificially acquired phototrophic metabolism, an ancestral E. coli expressing GR was adaptively evolved in a chemostat reactor with constant illumination and limited glucose conditions...
June 15, 2017: Microbial Cell Factories
https://www.readbyqxmd.com/read/28615682/improved-retinal-function-in-rcs-rats-after-suppressing-the-over-activation-of-mglur5
#10
Jiaman Dai, Yan Fu, Yuxiao Zeng, Shiying Li, Zheng Qin Yin
Müller cells maintain retinal synaptic homeostasis by taking up glutamate from the synaptic cleft and transporting glutamine back to the neurons. To study the interaction between Müller cells and photoreceptors, we injected either DL-α-aminoadipate or L-methionine sulfoximine-both inhibitors of glutamine synthetase-subretinally in rats. Following injection, the a-wave of the electroretinogram (ERG) was attenuated, and metabotropic glutamate receptor 5 (mGluR5) was activated. Selective antagonism of mGluR5 by 2-methyl-6-(phenylethynyl)-pyridine increased the ERG a-wave amplitude and also increased rhodopsin expression...
June 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28613900/solid-state-nmr-provides-evidence-for-small-amplitude-slow-domain-motions-in-a-multi-spanning-transmembrane-%C3%AE-helical-protein
#11
Daryl Good, Charlie Pham, Jacob Jagas, Józef R Lewandowski, Vladimir Ladizhansky
Proteins are dynamic entities and populate ensembles of conformations. Transitions between states within a conformational ensemble occur over a broad spectrum of amplitude and time scales, and are often related to biological function. Whereas solid-state NMR (SSNMR) spectroscopy has recently been used to characterize conformational ensembles of proteins in the microcrystalline states, its applications to membrane proteins remain limited. Here we use SSNMR to study conformational dynamics of a seven-helical transmembrane (TM) protein, Anabaena Sensory Rhodopsin (ASR) reconstituted in lipids...
June 14, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28612236/using-optogenetics-to-assess-neuroendocrine-modulation-of-heart-rate-in-drosophila-melanogaster-larvae
#12
Cole Malloy, Jacob Sifers, Angela Mikos, Aya Samadi, Aya Omar, Christina Hermanns, Robin L Cooper
The Drosophila melanogaster heart has become a principal model in which to study cardiac physiology and development. While the morphology of the heart in Drosophila and mammals is different, many of the molecular mechanisms that underlie heart development and function are similar and function can be assessed by similar physiological measurements, such as cardiac output, rate, and time in systole or diastole. Here, we have utilized an intact, optogenetic approach to assess the neural influence on heart rate in the third instar larvae...
June 13, 2017: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
https://www.readbyqxmd.com/read/28611220/energetics-and-dynamics-of-a-light-driven-sodium-pumping-rhodopsin
#13
Carl-Mikael Suomivuori, Ana P Gamiz-Hernandez, Dage Sundholm, Ville R I Kaila
The conversion of light energy into ion gradients across biological membranes is one of the most fundamental reactions in primary biological energy transduction. Recently, the structure of the first light-activated Na(+) pump, Krokinobacter eikastus rhodopsin 2 (KR2), was resolved at atomic resolution [Kato HE, et al. (2015) Nature 521:48-53]. To elucidate its molecular mechanism for Na(+) pumping, we perform here extensive classical and quantum molecular dynamics (MD) simulations of transient photocycle states...
June 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28603013/oxytocin-oxt-stimulated-inhibition-of-kir7-1-activity-is-through-pip2-dependent-ca-2-response-of-the-oxytocin-receptor-in-the-retinal-pigment-epithelium-in-vitro
#14
Nathaniel York, Patrick Halbach, Michelle A Chiu, Ian M Bird, De-Ann M Pillers, Bikash R Pattnaik
Oxytocin (OXT) is a neuropeptide that activates the oxytocin receptor (OXTR), a rhodopsin family G-protein coupled receptor. Our localization of OXTR to the retinal pigment epithelium (RPE), in close proximity to OXT in the adjacent photoreceptor neurons, leads us to propose that OXT plays an important role in RPE-retinal communication. An increase of RPE [Ca(2+)]i in response to OXT stimulation implies that the RPE may utilize oxytocinergic signaling as a mechanism by which it accomplishes some of its many roles...
June 8, 2017: Cellular Signalling
https://www.readbyqxmd.com/read/28601011/developmental-toxicity-of-hydroxylated-chrysene-metabolites-in-zebrafish-embryos
#15
Graciel Diamante, Gabrielle do Amaral E Silva Müller, Norma Menjivar-Cervantes, Elvis Genbo Xu, David C Volz, Afonso Celso Dias Bainy, Daniel Schlenk
One of the primary sources of polycyclic aromatic hydrocarbons (PAHs) in marine environments is oil. Photochemical oxidation and microbial transformation of PAH-containing oils can result in the formation of oxygenated products. Among the PAHs in crude oil, chrysene is one of the most persistent within the water column and may be transformed to 2- and 6-hydroxychrysene (OHCHR). Both of these compounds have been shown to activate (2-OHCHR) and antagonize (6-OHCHR) the estrogen receptor (ER). Previous studies in our lab have shown that estrogen can significantly alter zebrafish development...
June 3, 2017: Aquatic Toxicology
https://www.readbyqxmd.com/read/28598695/unconventional-roles-of-opsins
#16
Nicole Y Leung, Craig Montell
Rhodopsin is the classical light sensor. Although rhodopsin has long been known to be important for image formation in the eye, the requirements for opsins in non-image formation and in extraocular light sensation were revealed much later. Most recent is the demonstration that an opsin in the fruit fly, Drosophila melanogaster, is expressed in pacemaker neurons in the brain and functions in light entrainment of circadian rhythms. However, the biggest surprise is that opsins have light-independent roles, countering more than a century of dogma that they function exclusively as light sensors...
June 9, 2017: Annual Review of Cell and Developmental Biology
https://www.readbyqxmd.com/read/28595408/probing-the-remarkable-thermal-kinetics-of-visual-rhodopsin-with-e181q-and-s186a-mutants
#17
Ying Guo, Heidi P Hendrickson, Pablo E Videla, Ya-Na Chen, Junming Ho, Sivakumar Sekharan, Victor S Batista, John C Tully, Elsa C Y Yan
We recently reported a very unusual temperature dependence of the rate of thermal reaction of wild type bovine rhodopsin: the Arrhenius plot exhibits a sharp "elbow" at 47 °C and, in the upper temperature range, an unexpectedly large activation energy (114 ± 8 kcal/mol) and an enormous prefactor (10(72±5) s(-1)). In this report, we present new measurements and a theoretical model that establish convincingly that this behavior results from a collective, entropy-driven breakup of the rigid hydrogen bonding networks (HBNs) that hinder the reaction at lower temperatures...
June 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28593195/lake-bacterial-assemblage-composition-is-sensitive-to-biological-disturbance-caused-by-an-invasive-filter-feeder
#18
Vincent J Denef, Hunter J Carrick, Joann Cavaletto, Edna Chiang, Thomas H Johengen, Henry A Vanderploeg
One approach to improve forecasts of how global change will affect ecosystem processes is to better understand how anthropogenic disturbances alter bacterial assemblages that drive biogeochemical cycles. Species invasions are important contributors to global change, but their impacts on bacterial community ecology are rarely investigated. Here, we studied direct impacts of invasive dreissenid mussels (IDMs), one of many invasive filter feeders, on freshwater lake bacterioplankton. We demonstrated that direct effects of IDMs reduced bacterial abundance and altered assemblage composition by preferentially removing larger and particle-associated bacteria...
May 2017: MSphere
https://www.readbyqxmd.com/read/28591604/g-protein-coupled-receptors-contain-two-conserved-packing-clusters
#19
Omar B Sanchez-Reyes, Aidan L G Cooke, Dale B Tranter, Dawood Rashid, Markus Eilers, Philip J Reeves, Steven O Smith
G protein-coupled receptors (GPCRs) have evolved a seven-transmembrane helix framework that is responsive to a wide range of extracellular signals. An analysis of the interior packing of family A GPCR crystal structures reveals two clusters of highly packed residues that facilitate tight transmembrane helix association. These clusters are centered on amino acid positions 2.47 and 4.53, which are highly conserved as alanine and serine, respectively. Ala2.47 mediates the interaction between helices H1 and H2, while Ser4...
June 6, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28569420/rhodopsin-t17m-mutant-inhibits-complement-c3-secretion-in-retinal-pigment-epithelium-via-ros-induced-downregulation-of-twist1
#20
Siqi Xiong, Yixin Yu, Xiaoyun Zhou, Xiaobo Xia, Haibo Jiang
Rhodopsin mutations cause autosomal dominant form of retinitis pigmentosa (RP). T17M rhodopsin predisposes cells to endoplasmic reticulum stress induced apoptosis. However, the pathogenic role of T17M rhodopsin in RP is not completely understood. Complement C3 has a protective role in RP pathogenesis. This study aimed to investigate whether T17M rhodopsin regulates C3 secretion in retinal pigment epithelium. The human retinal pigment epithelial cell line (ARPE-19) was engineered to overexpress wide-type (WT) and T17M rhodopsin...
June 1, 2017: Journal of Cellular Biochemistry
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