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https://www.readbyqxmd.com/read/28101376/atpase-activity-tightly-regulates-reca-nucleofilaments-to-promote-homologous-recombination
#1
Bailin Zhao, Dapeng Zhang, Chengmin Li, Zheng Yuan, Fangzhi Yu, Shangwei Zhong, Guibin Jiang, Yun-Gui Yang, X Chris Le, Michael Weinfeld, Ping Zhu, Hailin Wang
Homologous recombination (HR), catalyzed in an evolutionarily conserved manner by active RecA/Rad51 nucleofilaments, maintains genomic integrity and promotes biological evolution and diversity. The structures of RecA/Rad51 nucleofilaments provide information critical for the entire HR process. By exploiting a unique capillary electrophoresis-laser-induced fluorescence polarization assay, we have discovered an active form of RecA nucleofilament, stimulated by ATP hydrolysis, that contains mainly unbound nucleotide sites...
2017: Cell Discovery
https://www.readbyqxmd.com/read/28100611/the-envelope-gene-of-transmitted-hiv-1-resists-a-late-ifn%C3%AE-induced-block
#2
Suzannah J Rihn, Toshana L Foster, Idoia Busnadiego, Muhamad Afiq Aziz, Joseph Hughes, Stuart J D Neil, Sam J Wilson
: Type I interferon (IFN) signaling engenders an antiviral state that likely plays an important role in constraining HIV-1 transmission and contributes to defining subsequent AIDS pathogenesis. Type II IFN (IFNγ) also induces an antiviral state but is often primarily considered to be an immunomodulatory cytokine. We report that IFNγ stimulation can induce an antiviral state that can be both distinct from that of type I interferon, and can potently inhibit HIV-1 in primary CD4+ T cells and a number of human cell lines...
January 18, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28099529/a-possible-role-of-the-full-length-nascent-protein-in-post-translational-ribosome-recycling
#3
Debasis Das, Dibyendu Samanta, Arpita Bhattacharya, Arunima Basu, Anindita Das, Jaydip Ghosh, Abhijit Chakrabarti, Chanchal Das Gupta
Each cycle of translation initiation in bacterial cell requires free 50S and 30S ribosomal subunits originating from the post-translational dissociation of 70S ribosome from the previous cycle. Literature shows stable dissociation of 70S from model post-termination complexes by the concerted action of Ribosome Recycling Factor (RRF) and Elongation Factor G (EF-G) that interact with the rRNA bridge B2a/B2b joining 50S to 30S. In such experimental models, the role of full-length nascent protein was never considered seriously...
2017: PloS One
https://www.readbyqxmd.com/read/28094246/development-of-sr-incorporated-biphasic-calcium-phosphate-bone-cement
#4
Hui Zhu, Dagang Guo, Wenli Qi, Kewei Xu
To follow the design strategy of traditional biphasic calcium phosphate (BCP) ceramic, in the present study, strontium-doped biphasic calcium phosphate bone cement (Sr-BCPC) composites comprising Sr-β-tricalcium phosphate (TCP)/Sr-hydroxyapatite (HAP) had been prepared for the first time using Sr x -β-TCP/tetracalcium phosphate (TTCP) as a cement powder and diluted phosphoric acid as a cement liquid. The phase composition, setting time, compressive strength, washout resistance, in vitro degradation rate, microstructure evolutions, hydration dynamics and cytotoxicity of Sr-BCPC at various Sr contents were intensively investigated...
January 17, 2017: Biomedical Materials
https://www.readbyqxmd.com/read/28092358/recurrent-rna-motifs-as-scaffolds-for-genetically-encodable-small-molecule-biosensors
#5
Ely B Porter, Jacob T Polaski, Makenna M Morck, Robert T Batey
Allosteric RNA devices are increasingly being viewed as important tools capable of monitoring enzyme evolution, optimizing engineered metabolic pathways, facilitating gene discovery and regulators of nucleic acid-based therapeutics. A key bottleneck in the development of these platforms is the availability of small-molecule-binding RNA aptamers that robustly function in the cellular environment. Although aptamers can be raised against nearly any desired target through in vitro selection, many cannot easily be integrated into devices or do not reliably function in a cellular context...
January 16, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28091849/dynamic-optical-absorption-characteristics-of-blood-after-slow-and-fast-heating
#6
Hao Jia, Bin Chen, Dong Li
Laser treatment is the most effective therapy in dermatology for vascular skin disorders, such as port-wine stains (PWS). Changes in heat-induced absorbance in blood must be determined for accurate numerical simulation and implementation of multi-pulse laser therapy for treatment of PWS. Thermally induced absorbance changes in hemoglobin in blood were compared in vitro between slow water bath heating and fast heating irradiated by using sub-millisecond Nd:YAG laser. Blood composition at different temperatures was calculated by comparing blood absorption spectra with those of pure HbO2, Hb, and metHb at room temperature...
January 13, 2017: Lasers in Medical Science
https://www.readbyqxmd.com/read/28088095/chemoreceptor-based-signal-sensing
#7
REVIEW
Miguel A Matilla, Tino Krell
Chemoreceptors are at the beginning of chemosensory signaling cascades that correspond to a major signal transduction mechanism. Chemoreceptors show a significant structural diversity of their ligand binding domains which present either a mono-modular or bi-modular arrangement. Although the majority of chemoreceptors are of unknown function, significant progress has been made in recent years in their functional annotation, which is reviewed here. In vitro ligand binding studies to recombinant ligand binding domains proved to be an efficient strategy to identify chemoreceptor functions...
January 11, 2017: Current Opinion in Biotechnology
https://www.readbyqxmd.com/read/28087782/mutation-supply-and-relative-fitness-shape-the-genotypes-of-ciprofloxacin-resistant-escherichia-coli
#8
Douglas L Huseby, Franziska Pietsch, Gerrit Brandis, Linnéa Garoff, Angelica Tegehall, Diarmaid Hughes
Ciprofloxacin is an important antibacterial drug targeting Type II topoisomerases, highly active against Gram-negatives including Escherichia coli The evolution of resistance to ciprofloxacin in E. coli always requires multiple genetic changes, usually including mutations affecting two different drug target genes, gyrA and parC Resistant mutants selected in vitro or in vivo can have many different mutations in target genes and efflux regulator genes that contribute to resistance. Among resistant clinical isolates the genotype, gyrA S83L D87N, parC S80I is significantly overrepresented suggesting that it has a selective advantage...
January 12, 2017: Molecular Biology and Evolution
https://www.readbyqxmd.com/read/28087697/development-of-high-affinity-and-high-specificity-inhibitors-of-metalloproteinase-14-through-computational-design-and-directed-evolution
#9
Valeria Arkadash, Gal Yosef, Jason Shirian, Itay Cohen, Yuval Horev, Moran Grossman, Irit Sagi, Evette S Radisky, Julia M Shifman, Niv Papo
Degradation of the extracellular matrices in the human body is controlled by matrix metalloproteinases (MMPs), a family of more than 20 homologous enzymes. Imbalance in MMP activity can result in many diseases, such as arthritis, cardiovascular diseases, neurological disorders, fibrosis, and cancers. Thus, MMPs present attractive targets for drug design and have been a focus for inhibitor design for as long as three decades. Yet, to date, all MMP inhibitors have failed in clinical trials because of their broad activity against numerous MMP family members and the serious side effects of the proposed treatment...
January 13, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28081260/comparative-genome-sequencing-reveals-within-host-genetic-changes-in-neisseria-meningitidis-during-invasive-disease
#10
Johanna Klughammer, Marcus Dittrich, Jochen Blom, Vera Mitesser, Ulrich Vogel, Matthias Frosch, Alexander Goesmann, Tobias Müller, Christoph Schoen
Some members of the physiological human microbiome occasionally cause life-threatening disease even in immunocompetent individuals. A prime example of such a commensal pathogen is Neisseria meningitidis, which normally resides in the human nasopharynx but is also a leading cause of sepsis and epidemic meningitis. Using N. meningitidis as model organism, we tested the hypothesis that virulence of commensal pathogens is a consequence of within host evolution and selection of invasive variants due to mutations at contingency genes, a mechanism called phase variation...
2017: PloS One
https://www.readbyqxmd.com/read/28078379/chitosan-sodium-tetradecyl-sulfate-hydrogel-characterization-and-preclinical-evaluation-of-a-novel-sclerosing-embolizing-agent-for-the-treatment-of-endoleaks
#11
Fatemeh Zehtabi, Vincent Dumont-Mackay, Ahmed Fatimi, Antony Bertrand-Grenier, Hélène Héon, Gilles Soulez, Sophie Lerouge
PURPOSE: To compare the efficacy of an embolization agent with sclerosing properties (made of chitosan and sodium tetradecyl sulfate, CH-STS) with a similar embolization agent but without sclerosing properties (made of chitosan, CH) in treating endoleaks in a canine endovascular aneurysm repair model. METHODS: Two chitosan-based radiopaque hydrogels were prepared, one with STS and one without STS. Their rheological, injectability, and embolizing properties were assessed in vitro; afterwards, their efficacy in occluding endoleaks was compared in a canine bilateral aneurysm model reproducing type I endoleaks (n = 9 each)...
January 11, 2017: Cardiovascular and Interventional Radiology
https://www.readbyqxmd.com/read/28076811/modeling-the-effect-of-curvature-on-the-collective-behavior-of-cells-growing-new-tissue
#12
Mohd Almie Alias, Pascal R Buenzli
The growth of several biological tissues is known to be controlled in part by local geometrical features, such as the curvature of the tissue interface. This control leads to changes in tissue shape that in turn can affect the tissue's evolution. Understanding the cellular basis of this control is highly significant for bioscaffold tissue engineering, the evolution of bone microarchitecture, wound healing, and tumor growth. Although previous models have proposed geometrical relationships between tissue growth and curvature, the role of cell density and cell vigor remains poorly understood...
January 10, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28074907/insights-into-an-evolutionary-strategy-leading-to-antibiotic-resistance
#13
Chun-Feng D Hou, Jian-Wei Liu, Charles Collyer, Nataša Mitić, Marcelo Monteiro Pedroso, Gerhard Schenk, David L Ollis
Metallo-β-lactamases (MBLs) with activity towards a broad-spectrum of β-lactam antibiotics have become a major threat to public health, not least due to their ability to rapidly adapt their substrate preference. In this study, the capability of the MBL AIM-1 to evade antibiotic pressure by introducing specific mutations was probed by two alternative methods, i.e. site-saturation mutagenesis (SSM) of active site residues and in vitro evolution. Both approaches demonstrated that a single mutation in AIM-1 can greatly enhance a pathogen's resistance towards broad spectrum antibiotics without significantly compromising the catalytic efficiency of the enzyme...
January 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28070749/an-automated-microemboli-detection-and-classification-system-using-backscatter-rf-signals-and-differential-evolution
#14
Karim Ferroudji, Nabil Benoudjit, Ayache Bouakaz
Embolic phenomena, whether air or particulate emboli, can induce immediate damages like heart attack or ischemic stroke. Embolus composition (gaseous or particulate matter) is vital in predicting clinically significant complications. Embolus detection using Doppler methods have shown their limits to differentiate solid and gaseous embolus. Radio-frequency (RF) ultrasound signals backscattered by the emboli contain additional information on the embolus in comparison to the traditionally used Doppler signals...
January 9, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28068310/visualizing-the-secondary-and-tertiary-architectural-domains-of-lncrna-repa
#15
Fei Liu, Srinivas Somarowthu, Anna Marie Pyle
Long noncoding RNAs (lncRNAs) are important for gene expression, but little is known about their structures. RepA is a 1.6-kb mouse lncRNA comprising the same sequence as the 5' region of Xist, including A and F repeats. It has been proposed to facilitate the initiation and spread of X-chromosome inactivation, although its exact role is poorly understood. To gain insight into the molecular mechanism of RepA and Xist, we determined a complete phylogenetically validated secondary-structural map of RepA through SHAPE and DMS chemical probing of a homogeneously folded RNA in vitro...
January 9, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28067631/schwann-cells-are-activated-by-atp-released-from-neurons-in-an-in-vitro-cellular-model-of-miller-fisher-syndrome
#16
Umberto Rodella, Samuele Negro, Michele Scorzeto, Elisanna Bergamin, Kees Jalink, Cesare Montecucco, Nobuhiro Yuki, Michela Rigoni
The neuromuscular junction is exposed to different types of insults including mechanical traumas, toxins or autoimmune antibodies and, accordingly, has retained through evolution a remarkable ability to regenerate. Regeneration is driven by multiple signals that are exchanged among the cellular components of the junction. These signals are largely unknown.Miller Fisher syndrome is a variant of Guillain-Barré syndrome caused by autoimmune antibodies specific for epitopes of peripheral axon terminals. Using an animal model of Miller Fisher syndrome, we recently reported that a monoclonal anti-polysialoganglioside GQ1b antibody plus complement damages nerve terminals with production of mitochondrial hydrogen peroxide, that activates Schwann cells...
January 6, 2017: Disease Models & Mechanisms
https://www.readbyqxmd.com/read/28065274/probing-the-activity-of-eukaryotic-rhomboid-proteases-in-vitro
#17
B Cordier, M K Lemberg
Proteolysis within the membrane is a recent concept in biology. Rhomboid intramembrane serine proteases are conserved in evolution and serve as key switches in diverse cellular pathways ranging from signaling to protein degradation. Since deregulation of intramembrane proteolysis can lead to severe diseases including neurodegenerative disorders, dissecting their enzymatic function and specificity becomes crucial. As membrane proteins, their solubilization, and purification are technically challenging. As a start point for a comprehensive in vitro characterization of eukaryotic rhomboid proteases, we depict in this chapter a robust workflow to find the best conditions to obtain pure and active enzymes from a bacterial expression system...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28064476/chemoselective-coupling-preserves-the-substrate-integrity-of-surface-immobilized-oligonucleotides-for-emulsion-pcr-based-gene-library-construction
#18
Marie L Malone, Valerie J Cavett, Brian M Paegel
Combinatorial bead libraries figure prominently in next-generation sequencing and are also important tools for in vitro evolution. The most common methodology for generating such bead libraries, emulsion PCR (emPCR), enzymatically extends bead-immobilized oligonucleotide PCR primers in emulsion droplets containing a single progenitor library member. Primers are almost always immobilized on beads via noncovalent biotin-streptavidin binding. Here, we describe covalent bead functionalization with primers (∼10(6) primers/2...
January 9, 2017: ACS Combinatorial Science
https://www.readbyqxmd.com/read/28063194/evolution-of-copper-resistance-in-the-kiwifruit-pathogen-pseudomonas-syringae-pv-actinidiae-through-acquisition-of-integrative-conjugative-elements-and-plasmids
#19
Elena Colombi, Christina Straub, Sven Künzel, Matthew D Templeton, Honour C McCann, Paul B Rainey
Horizontal gene transfer can precipitate rapid evolutionary change. In 2010 the global pandemic of kiwifruit canker disease caused by Pseudomonas syringae pv. actinidiae (Psa) reached New Zealand. At the time of introduction, the single clone responsible for the outbreak was sensitive to copper, however, analysis of a sample of isolates taken in 2015 and 2016 showed that a quarter were copper resistant. Genome sequences of seven strains showed that copper resistance - comprising czc/cusABC and copABCD systems - along with resistance to arsenic and cadmium, was acquired via uptake of integrative conjugative elements (ICEs), but also plasmids...
January 7, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28062831/glioblastoma-on-a-microfluidic-chip-generating-pseudopalisades-and-enhancing-aggressiveness-through-blood-vessel-obstruction-events
#20
Jose M Ayuso, Rosa Monge, Alicia Martínez-González, María Virumbrales-Muñoz, Guillermo A Llamazares, Javier Berganzo, Aurelio Hernández-Laín, Jorge Santolaria, Manuel Doblaré, Christopher Hubert, Jeremy N Rich, Pilar Sánchez-Gómez, Víctor M Pérez-García, Ignacio Ochoa, Luis J Fernández
BACKGROUND: Glioblastoma (GBM) is one of the most lethal tumor types. Hypercellular regions, named pseudopalisades, are characteristic in these tumors and have been hypothesized to be waves of migrating glioblastoma cells. These "waves" of cells are thought to be induced by oxygen and nutrient depletion caused by tumor-induced blood vessel occlusion. Although the universal presence of these structures in GBM tumors suggests that they may play an instrumental role in GBM's spread and invasion, the recreation of these structures in vitro has remained challenging...
January 6, 2017: Neuro-oncology
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