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https://www.readbyqxmd.com/read/29150982/visualization-within-the-ventricles-of-the-brain-a-micro-focus-x-ray-study
#1
Edwin John de Jager, André Francois du Plessis, Jakobus Willem Hoffman, Anna Catherina Oettlé, Marius Casparus Bosman
Conceptualization of the ventricular system of the brain by macroscopic studies is complicated by the lack of physical structure of these interconnected cavities. Dissection procedures designed to display the structures in the walls of the ventricles are destructive and not conducive for the appreciation of the ventricular system in its entirety. The application of Micro-focus X-ray tomography affords the possibility to appreciate hidden structures in a non-destructive manner. The aim of this study was to explore the possibility of using micro-focus X-ray tomography in the three-dimensional (3D) visualization of the ventricular system as well as the various neuroanatomical structures within its walls for educational purposes...
November 18, 2017: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
https://www.readbyqxmd.com/read/29150928/application-of-high-speed-counter-current-chromatography-and-hplc-to-separate-and-purify-of-three-polyacetylenes-from-platycodon-grandiflorum
#2
Bao Chen, Zhengbo Liu, Yuwei Zhang, Wei Li, Yanjun Sun, Yufang Wang, Yanhua Wang, Yinshi Sun
Three polyacetylenes were isolated and purified from Platycodon grandiflorum A. DC for the first time by high-speed counter-current chromatography using a two-phase solvent system composed of hexane/ethyl acetate/methanol/water (1:31:1:31, v/v/v/v) and high-performance liquid chromatography with an Agilent ZORBAX(®) SB-C18 column (4.6 mm × 150 mm, 5 μm). After separation by high-speed counter-current chromatography and high-performance liquid chromatography, we obtained 3.5 mg of platetyolin A, 4.1 mg of platetyolin B, and 18...
November 18, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/29150609/atomic-resolution-snapshot-of-leishmania-ribosome-inhibition-by-the-aminoglycoside-paromomycin
#3
Moran Shalev-Benami, Yan Zhang, Haim Rozenberg, Yuko Nobe, Masato Taoka, Donna Matzov, Ella Zimmerman, Anat Bashan, Toshiaki Isobe, Charles L Jaffe, Ada Yonath, Georgios Skiniotis
Leishmania is a single-celled eukaryotic parasite afflicting millions of humans worldwide, with current therapies limited to a poor selection of drugs that mostly target elements in the parasite's cell envelope. Here we determined the atomic resolution electron cryo-microscopy (cryo-EM) structure of the Leishmania ribosome in complex with paromomycin (PAR), a highly potent compound recently approved for treatment of the fatal visceral leishmaniasis (VL). The structure reveals the mechanism by which the drug induces its deleterious effects on the parasite...
November 17, 2017: Nature Communications
https://www.readbyqxmd.com/read/29150515/loop-of-streptomyces-feruloyl-esterase-plays-an-important-role-in-its-activity-of-releasing-ferulic-acid-from-biomass
#4
Misugi Uraji, Haruka Tamura, Eiichi Mizohata, Jiro Arima, Kun Wan, Ken'ichi Ogawa, Tsuyoshi Inoue, Tadashi Hatanaka
Feruloyl esterases (FAEs) are key enzymes required for the production of ferulic acid from agricultural biomass. Previously, we identified and characterized R18, an FAE from Streptomyces cinnamoneus NBRC 12852, which showed no sequence similarity with the known FAEs. To determine the region involved in its catalytic activity, we constructed chimeric enzymes using R18 and its homolog (TH2-18) from S. cinnamoneus strain TH-2. Although R18 and TH2-18 showed 74% identity in their primary sequence, the recombinant proteins of these two FAEs (rR18 and rTH2-18) showed very different specific activities toward ethyl ferulate...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29150182/mature-hippocampal-neurons-require-lis1-for-synaptic-integrity-implications-for-cognition
#5
Anamaria Sudarov, Xin-Jun Zhang, Leighton Braunstein, Eve LoCastro, Shawn Singh, Yu Taniguchi, Ashish Raj, Song-Hai Shi, Holly Moore, M Elizabeth Ross
BACKGROUND: Platelet-activating factor acetylhydrolase 1B1 (LIS1), a critical mediator of neuronal migration in developing brain, is expressed throughout life. However, relatively little is known about LIS1 function in the mature brain. We previously demonstrated that LIS1 involvement in the formation and turnover of synaptic protrusions and synapses of young brain after neuronal migration is complete. Here we examine the requirement for LIS1 to maintain hippocampal circuit function in adulthood...
September 23, 2017: Biological Psychiatry
https://www.readbyqxmd.com/read/29149833/g4-interacting-dna-helicases-and-polymerases-potential-therapeutic-targets
#6
Katrina Estep, Thomas J Butler, Jun Ding, Robert M Brosh
Guanine-rich DNA can fold into highly stable non-canonical four-stranded DNA structures called G-quadruplexes. These structures present obstacles for the DNA replication machinery, and it has been hypothesized that both eukaryotic DNA helicases and polymerases have evolved to resolve G4 DNA in vivo. Since the discovery of G-quadruplex DNA in the early 1960's, a number of studies have emerged reporting G-quadruplex DNA unfolding by helicase enzymes and DNA synthesis past G4 by specialized translesion polymerase enzymes...
November 16, 2017: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/29149699/tetrahymena-cilia-cap-is-built-in-a-multi-step-process-a-study-by-atomic-force-microscopy
#7
Cecília Seixas, João Gonçalves, Luís Viseu Melo, Helena Soares
Cilia are complex and dynamic organelles that have motility and sensory functions. Defects in cilia biogenesis and function are at the origin of human ciliopathies. In motile cilia, a basal body organizes the axoneme composed of nine microtubule doublets surrounding a central pair of singlet microtubules. The distal ends of axonemal microtubules are attached to the membrane by microtubule-capping structures. Little is known about the early steps of cilium assembly. Although cilia grow and resorb from their distal tips, it remains poorly understood where and when the components of the caps are first assembled...
October 20, 2017: Protist
https://www.readbyqxmd.com/read/29149555/mapping-the-reactions-in-a-single-zero-valent-iron-nanoparticle
#8
Lan Ling, Xiao-Yue Huang, Meirong Li, Wei-Xian Zhang
Nanoscale zero-valent iron (nZVI) posseses unique functionalities for metal-metalloid removal and sequestration. So far, direct evidence on the heavy metal-iron reactions in the solid phase is still limited due to low concentration of heavy metals and small size of nanoparticles. In this work, angstrom-resolution spectral mappings on the reactions of nZVI with chromate, arsenate, nickel, silver, cesium, and zinc ions are presented. This work was achieved with spherical aberration-corrected scanning transmission electron microscopy integrated with high-sensitivity X-ray energy-dispersive spectroscopy scanning transmission electron microscopy (XEDS-STEM)...
November 17, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29149542/spectrally-encoded-coherence-tomography-and-reflectometry-sectr-simultaneous-en-face-and-cross-sectional-imaging-at-2-gigapixels-per-second
#9
Mohamed T El-Haddad, Ivan Bozic, Yuankai K Tao
Non-invasive biological imaging is crucial for understanding in vivo structure and function. Optical coherence tomography (OCT) and reflectance confocal microscopy are two of the most widely used optical modalities for exogenous contrast-free high-resolution three-dimensional imaging in non-fluorescent scattering tissues. However, sample motion remains a critical barrier to raster-scanned acquisition and reconstruction of wide-field anatomically accurate volumetric datasets. We introduce spectrally encoded coherence tomography and reflectometry (SECTR), a high-speed multimodality system for simultaneous OCT and spectrally-encoded reflectance (SER) imaging...
November 17, 2017: Journal of Biophotonics
https://www.readbyqxmd.com/read/29149239/label-free-in-vivo-imaging-of-corneal-lymphatic-vessels-using-microscopic-optical-coherence-tomography
#10
Jens Horstmann, Hinnerk Schulz-Hildebrandt, Felix Bock, Sebastian Siebelmann, Eva Lankenau, Gereon Hüttmann, Philipp Steven, Claus Cursiefen
Purpose: Corneal neovascularization, in particular lymphangiogenesis, is a limiting factor in corneal transplant survival. Novel treatment approaches focus on (selective) inhibition and regression of lymphatic vessels. Imaging clinically invisible corneal lymphatic vessels is a prerequisite for these strategies. Using a murine model, this study investigates whether corneal lymphatic vessels can be imaged using microscopic optical coherence tomography (mOCT). Methods: Corneal neovascularization was induced by intrastromal placement of 11...
November 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29149016/oleanane-type-saponins-from-the-roots-of-ligulariopsis-shichuana-and-their-%C3%AE-glucosidase-inhibitory-activities
#11
Hai-Bo Wu, Ting-Ting Liu, Wen-Shu Wang, Jin-Chao Feng, Hong-Mei Tian
Five new oleanane-type saponins, named ligushicosides A-E, and three known oleanane-type saponins were isolated from the roots of Ligulariopsis shichuana. Their structures were established by a combination of spectroscopic techniques, including 1D and 2D NMR and high resolution electrospray ionization mass spectroscopy (HR-ESI-MS). Furthermore, all isolates were evaluated for their yeast α-glucosidase inhibitory effects and exhibited potent inhibition against α-glucosidase, while compounds 1 and 2 showed excellent inhibitory activities...
November 17, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29148971/convergence-of-topological-domain-boundaries-insulators-and-polytene-interbands-revealed-by-high-resolution-mapping-of-chromatin-contacts-in-the-early-drosophila-melanogaster-embryo
#12
Michael R Stadler, Jenna E Haines, Michael Eisen
High-throughput assays of three-dimensional interactions of chromosomes have shed considerable light on the structure of animal chromatin. Despite this progress, the precise physical nature of observed structures and the forces that govern their establishment remain poorly understood. Here we present high resolution Hi-C data from early Drosophila embryos. We demonstrate that boundaries between topological domains of various sizes map to DNA elements that resemble classical insulator elements: short genomic regions sensitive to DNase digestion that are strongly bound by known insulator proteins and are frequently located between divergent promoters...
November 17, 2017: ELife
https://www.readbyqxmd.com/read/29148886/an-experimental-study-of-the-effects-of-chemically-dispersed-oil-on-feather-structure-and-waterproofing-in-common-murres-uria-aalge
#13
Emily R Whitmer, Becky A Elias, Danielle J Harvey, Michael H Ziccardi
Following an oil spill in the marine environment, chemical dispersants, which increase oil droplet formation and distribution into the water column, are assumed to provide a net benefit to seabirds by reducing the risk of exposure to oil on the water surface. However, few data are available regarding acute, external impacts of exposure to dispersed oil. We evaluated the effects of known concentrations of dispersant and crude oil in artificial seawater on live Common Murres (Uria aalge). Waterproofing and microscopic feather geometry were evaluated over time and compared to pre-exposure values...
November 17, 2017: Journal of Wildlife Diseases
https://www.readbyqxmd.com/read/29148786/n-alkanethiols-directly-grown-on-a-bare-si-111-surface-from-disordered-to-ordered-transition
#14
Lo-Yueh Chang, Yen-Chien Kuo, Hung Wei Shiu, Chia-Hsin Wang, Yao-Chang Lee, Yaw-Wen Yang, Shangjr Gwo, Chia-Hao Chen
We observed the growth phase transition of n-alkanethiols (AT), CH3(CH2)n-1SH, n = 4 ~16, directly implanted on a bare Si(111) surface, forming an AT monolayer. These monolayers were characterized with static water-contact angle, high-resolution X-ray photoelectron spectroscopy, near-edge X-ray fine-structure spectroscopy and grazing-angle reflection absorption Fourier-transform infrared spectroscopy. The integrated spectral results indicated that the implanted n-AT molecules formed a self-oriented and densely packed monolayer through formation of an S-Si bond...
November 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29148254/connecting-color-with-assembly-in-the-fluorescent-b-phycoerythrin-protein-complex
#15
Aneika C Leney, Aline Tschanz, Albert J R Heck
Phycoerythrin is the major light-harvesting pigment protein in red algae and is nowadays widely used as a fluorescent probe in biotechnological applications such as flow cytometry and immunofluorescence microscopy. In addition, it has had substantial economic impact due to its potential as a natural food colorant. However, knowledge on the precise molecular composition of phycoerythrin is limited. Here, we use a combination of high resolution native mass spectrometry (MS) and fluorescence spectroscopy to characterize the assembly properties of the B-phycoerythrin protein complex from Porphyridium cruentum...
November 17, 2017: FEBS Journal
https://www.readbyqxmd.com/read/29147699/strain-relaxation-and-ambipolar-electrical-transport-in-gaas-insb-core-shell-nanowires
#16
Torsten Rieger, Patrick Zellekens, Natalia Demarina, Ali Al Hassan, Franz Josef Hackemüller, Hans Lüth, Ullrich Pietsch, Thomas Schäpers, Detlev Grützmacher, Mihail Ion Lepsa
The growth, crystal structure, strain relaxation and room temperature transport characteristics of GaAs/InSb core-shell nanowires grown using molecular beam epitaxy are investigated. Due to the large lattice mismatch between GaAs and InSb of 14%, a transition from island-based to layer-like growth occurs during the formation of the shell. High resolution transmission electron microscopy in combination with geometric phase analyses as well as X-ray diffraction with synchrotron radiation are used to investigate the strain relaxation and prove the existence of different dislocations relaxing the strain on zinc blende and wurtzite core-shell nanowire segments...
November 17, 2017: Nanoscale
https://www.readbyqxmd.com/read/29147002/capturing-an-initial-intermediate-during-the-p450nor-enzymatic-reaction-using-time-resolved-xfel-crystallography-and-caged-substrate
#17
Takehiko Tosha, Takashi Nomura, Takuma Nishida, Naoya Saeki, Kouta Okubayashi, Raika Yamagiwa, Michihiro Sugahara, Takanori Nakane, Keitaro Yamashita, Kunio Hirata, Go Ueno, Tetsunari Kimura, Tamao Hisano, Kazumasa Muramoto, Hitomi Sawai, Hanae Takeda, Eiichi Mizohata, Ayumi Yamashita, Yusuke Kanematsu, Yu Takano, Eriko Nango, Rie Tanaka, Osamu Nureki, Osami Shoji, Yuka Ikemoto, Hironori Murakami, Shigeki Owada, Kensuke Tono, Makina Yabashi, Masaki Yamamoto, Hideo Ago, So Iwata, Hiroshi Sugimoto, Yoshitsugu Shiro, Minoru Kubo
Time-resolved serial femtosecond crystallography using an X-ray free electron laser (XFEL) in conjunction with a photosensitive caged-compound offers a crystallographic method to track enzymatic reactions. Here we demonstrate the application of this method using fungal NO reductase, a heme-containing enzyme, at room temperature. Twenty milliseconds after caged-NO photolysis, we identify a NO-bound form of the enzyme, which is an initial intermediate with a slightly bent Fe-N-O coordination geometry at a resolution of 2...
November 17, 2017: Nature Communications
https://www.readbyqxmd.com/read/29146944/structure-of-the-transcription-activator-target-tra1-within-the-chromatin-modifying-complex-saga
#18
Grigory Sharov, Karine Voltz, Alexandre Durand, Olga Kolesnikova, Gabor Papai, Alexander G Myasnikov, Annick Dejaegere, Adam Ben Shem, Patrick Schultz
The transcription co-activator complex SAGA is recruited to gene promoters by sequence-specific transcriptional activators and by chromatin modifications to promote pre-initiation complex formation. The yeast Tra1 subunit is the major target of acidic activators such as Gal4, VP16, or Gcn4 but little is known about its structural organization. The 430 kDa Tra1 subunit and its human homolog the transformation/transcription domain-associated protein TRRAP are members of the phosphatidyl 3-kinase-related kinase (PIKK) family...
November 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/29146870/structure-of-the-yeast-spliceosomal-postcatalytic-p-complex
#19
Shiheng Liu, Xueni Li, Lingdi Zhang, Jiansen Jiang, Ryan C Hill, Yanxiang Cui, Kirk C Hansen, Z Hong Zhou, Rui Zhao
The spliceosome undergoes dramatic changes in a splicing cycle. Structures of B, B(act), C, C*, and ILS complexes revealed mechanisms of 5' splice site (ss) recognition, branching, and intron release, but lacked information on 3' ss recognition, exon ligation and release. Here, we report a cryoEM structure of the postcatalytic P complex at 3.3Å resolution, revealing that 3' ss is mainly recognized through non-Watson-Crick basepairing with the 5' ss and branch point. Furthermore, an unidentified protein becomes stably associated with the P complex, securing the 3' exon and potentially regulating Prp22 activity...
November 16, 2017: Science
https://www.readbyqxmd.com/read/29146813/structural-basis-of-bacterial-transcription-activation
#20
Bin Liu, Chuan Hong, Rick K Huang, Zhiheng Yu, Thomas A Steitz
In bacteria, the activation of gene transcription at many promoters is simple and only involves a single activator. The cyclic adenosine 3',5'-monophosphate receptor protein (CAP), a classic activator, is able to activate transcription independently through two different mechanisms. Understanding the class I mechanism requires an intact transcription activation complex (TAC) structure at a high resolution. Here we report a high-resolution cryo-electron microscopy structure of an intact Escherichia coli class I TAC containing a CAP dimer, a σ(70)-RNA polymerase (RNAP) holoenzyme, a complete class I CAP-dependent promoter DNA, and a de novo synthesized RNA oligonucleotide...
November 17, 2017: Science
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