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Dynamic nuclear polarization

Yusuke Kimata, Takumi Higaki, Tomokazu Kawashima, Daisuke Kurihara, Yoshikatsu Sato, Tomomi Yamada, Seiichiro Hasezawa, Frederic Berger, Tetsuya Higashiyama, Minako Ueda
The asymmetric cell division of the zygote is the initial and crucial developmental step in most multicellular organisms. In flowering plants, whether zygote polarity is inherited from the preexisting organization in the egg cell or reestablished after fertilization has remained elusive. How dynamically the intracellular organization is generated during zygote polarization is also unknown. Here, we used a live-cell imaging system with Arabidopsis zygotes to visualize the dynamics of the major elements of the cytoskeleton, microtubules (MTs), and actin filaments (F-actins), during the entire process of zygote polarization...
November 22, 2016: Proceedings of the National Academy of Sciences of the United States of America
Simon Gross, Christoph Barmet, Benjamin E Dietrich, David O Brunner, Thomas Schmid, Klaas P Pruessmann
High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude...
December 2, 2016: Nature Communications
Meenakumari V, Hideo Utsumi, A Jawahar, A Milton Franklin Benial
In this work, the detailed studies of electron spin resonance (ESR) and Overhauser enhanced magnetic resonance imaging (OMRI) were carried out for permeable nitroxyl spin probe, MC-PROXYL as a function of agent concentration in liposomal solution. In order to compare the impermeable nature of nitroxyl radical, the study was also carried out only at 2mM concentration of carboxy-PROXYL. The ESR parameters were estimated using L- band and 300 MHz ESR spectrometers. The line width broadening was measured as a function of agent concentration in liposomal solution...
November 28, 2016: Journal of Liposome Research
Ines Teichert
The ascomycete Sordaria macrospora has a long history as a model organism for studying fungal sexual development. Starting from an ascospore, sexual fruiting bodies (perithecia) develop within seven days and discharge new ascospores. Sexual development has been studied in detail, revealing genes required for perithecium formation and ascospore germination. However, the germination process per se has not yet been examined. Here I analyze nuclear dynamics during ascospore germination using a fluorescently labeled histone...
November 23, 2016: Fungal Genetics and Biology: FG & B
Kasper Wigh Lipsø, Sean Bowen, Oleksandr Rybalko, Jan Henrik Ardenkjær-Larsen
We demonstrate a method for the preparation of hyperpolarized water by dissolution Dynamic Nuclear Polarization at high magnetic field. Protons were polarized at 6.7T and 1.1K to >70% with frequency modulated microwave irradiation at 188GHz. 97.2±0.7% of the radical was extracted from the sample in the dissolution in a two-phase system. 16±1mL of 5.0M (1)H in D2O with a polarization of 13.0±0.9% in the liquid state was obtained, corresponding to an enhancement factor of 4000±300 compared to the thermal equilibrium at 9...
November 18, 2016: Journal of Magnetic Resonance
Daniel Stöppler, Chen Song, Barth-Jan van Rossum, Michel-Andreas Geiger, Christina Lang, Maria-Andrea Mroginski, Anil Pandurang Jagtap, Snorri Th Sigurdsson, Jörg Matysik, Jon Hughes, Hartmut Oschkinat
Phytochromes are red/far-red photochromic photoreceptors acting as master regulators of development in higher plants, thereby controlling transcription of about 20 % of their genes. Light-induced isomerization of the bilin chromophore leads to large rearrangements in protein structure, whereby the role of protonation dynamics and charge distribution is of particular interest. To help unravel the inherent mechanisms, we present two-dimensional dynamic nuclear polarization (DNP) enhanced solid-state magic-angle spinning (MAS) NMR spectra of the functional sensory module of the cyanobacterial phytochrome Cph1...
November 23, 2016: Angewandte Chemie
Dennis Kurzbach, Emmanuelle M M Weber, Aditya Jhajharia, Samuel F Cousin, Aude Sadet, Sina Marhabaie, Estel Canet, Nicolas Birlirakis, Jonas Milani, Sami Jannin, Dmitry Eshchenko, Alia Hassan, Roberto Melzi, Stephan Luetolf, Marco Sacher, Marc Rossire, James Kempf, Joost A B Lohman, Matthias Weller, Geoffrey Bodenhausen, Daniel Abergel
We present novel means to hyperpolarize deuterium nuclei in (13)CD2 groups at cryogenic temperatures. The method is based on cross-polarization from (1)H to (13)C and does not require any radio-frequency fields applied to the deuterium nuclei. After rapid dissolution, a new class of long-lived spin states can be detected indirectly by (13)C NMR in solution. These long-lived states result from a sextet-triplet imbalance (STI) that involves the two equivalent deuterons with spin I = 1. An STI has similar properties as a triplet-singlet imbalance that can occur in systems with two equivalent I = 12 spins...
November 21, 2016: Journal of Chemical Physics
Hellmut Eckert
Electron and nuclear spins are extremely sensitive probes of their local structural and dynamic surroundings. Their Zeeman energy levels are modified by different types of local magnetic and electric fields created by their structural environment, which influence their magnetic resonance condition. For this reason, electron spin resonance (ESR) and nuclear magnetic resonance (NMR) spectroscopies have become extremely powerful tools of structural analysis, which are being widely used for the structural characterization of complex solids...
November 15, 2016: Chemistry: a European Journal
K Veyrinas, V Gruson, S J Weber, L Barreau, T Ruchon, J-F Hergott, J-C Houver, R R Lucchese, P Salières, D Dowek
Due to the intimate anisotropic interaction between an XUV light field and a molecule resulting in photoionization (PI), molecular frame photoelectron angular distributions (MFPADs) are most sensitive probes of both electronic/nuclear dynamics and the polarization state of the ionizing light field. Consequently, they encode the complex dipole matrix elements describing the dynamics of the PI transition, as well as the three normalized Stokes parameters s1, s2, s3 characterizing the complete polarization state of the light, operating as molecular polarimetry...
November 17, 2016: Faraday Discussions
Leslie Mazuel, Rolf F Schulte, Aurélie Cladière, Claudine Spéziale, Marie Lagrée, Martin Leremboure, Betty Jean, Franck Durif, Carine Chassain
PURPOSE: Changes in glutamate (Glu) levels occur in a number of neurodegenerative diseases. We proposed the use of (13)C spectroscopy and the highly amplified signal generated by hyperpolarization to achieve spatial and temporal resolutions adequate for in vivo studies of Glu metabolism in the healthy rat brain. Thus, we investigated uptake of hyperpolarized [1(-13C)]Glu after a temporary blood-brain barrier (BBB) disruption protocol and its conversion to glutamine (Gln) in the brain...
November 8, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Patricia Hernández-Ortiz, Eduardo A Espeso
The response of Aspergilli to elevated concentrations of extracellular calcium and manganese, or environmental alkalinization is mediated by CrzA, a calcineurin-responsive transcription factor (TF). CrzA is the effector of a signaling pathway which includes the apical protein's calmodulin and calcineurin, and the protein kinases GskA and CkiA. Preferentially located in the cytoplasm, CrzA is the only element of the pathway modifying its localization under those stress conditions, being imported into nuclei...
November 8, 2016: Cellular Signalling
Siddharth Dhomkar, Jacob Henshaw, Harishankar Jayakumar, Carlos A Meriles
The negatively charged nitrogen vacancy (NV(-)) center in diamond is the focus of widespread attention for applications ranging from quantum information processing to nanoscale metrology. Although most work so far has focused on the NV(-) optical and spin properties, control of the charge state promises complementary opportunities. One intriguing possibility is the long-term storage of information, a notion we hereby introduce using NV-rich, type 1b diamond. As a proof of principle, we use multicolor optical microscopy to read, write, and reset arbitrary data sets with two-dimensional (2D) binary bit density comparable to present digital-video-disk (DVD) technology...
October 2016: Science Advances
Michel-Andreas Geiger, Marcella Orwick-Rydmark, Katharina Märker, W Trent Franks, Dmitry Akhmetzyanov, Daniel Stöppler, Maximilian Zinke, Edgar Specker, Marc Nazaré, Anne Diehl, Barth-Jan van Rossum, Fabien Aussenac, Thomas Prisner, Ümit Akbey, Hartmut Oschkinat
Dynamic nuclear polarization exploits electron spin polarization to boost signal-to-noise in magic-angle-spinning (MAS) NMR, creating new opportunities in materials science, structural biology, and metabolomics studies. Since protein NMR spectra recorded under DNP conditions can show improved spectral resolution at 180-200 K compared to 110 K, we investigate the effects of AMUPol and various deuterated TOTAPOL isotopologues on sensitivity and spectral resolution at these temperatures, using proline and reproducibly prepared SH3 domain samples...
October 28, 2016: Physical Chemistry Chemical Physics: PCCP
Aurélien Bornet, Arthur Pinon, Aditya Jhajharia, Mathieu Baudin, Xiao Ji, Lyndon Emsley, Geoffrey Bodenhausen, Jan Henrik Ardenkjaer-Larsen, Sami Jannin
Dissolution dynamic nuclear polarization (D-DNP) has become a method of choice to enhance signals in nuclear magnetic resonance (NMR). Recently, we have proposed to combine cross-polarization (CP) with D-DNP to provide high polarization P((13)C) in short build-up times. In this paper, we show that switching microwave irradiation off for a few hundreds of milliseconds prior to CP can significantly boost the efficiency. By implementing microwave gating, (13)C polarizations on sodium [1-(13)C]acetate as high as 64% could be achieved with a polarization build-up time constant as short as 160 s...
October 26, 2016: Physical Chemistry Chemical Physics: PCCP
Abhishek Banerjee, Arnab Dey, Narayanan Chandrakumar
Solution-state Overhauser dynamic nuclear polarization (ODNP) at moderate fields, performed by saturating the electron spin resonance (ESR) of a free radical added to the sample of interest, is well known to lead to significant NMR signal enhancements in the steady state, owing to electron-nuclear cross-relaxation. Here it is shown that under conditions which limit radical access to the molecules of interest, the time course of establishment of ODNP can provide a unique window into internuclear cross-relaxation, and reflects relatively slow molecular motions...
November 14, 2016: Angewandte Chemie
Alexander Karabanov, Grzegorz Kwiatkowski, Carlo U Perotto, Daniel Wiśniewski, Jonathan McMaster, Igor Lesanovsky, Walter Köckenberger
A theory of dynamic nuclear polarisation (DNP) by thermal mixing is suggested based on purely quantum considerations. A minimal 6-level microscopic model is developed to test the theory and link it to the well-known thermodynamic model. Optimal conditions for the nuclear polarization enhancement and effects of inhomogeneous broadening of the electron resonance are discussed. Macroscopic simulations of nuclear polarization spectra displaying good agreement with experiments, involving BDPA and trityl free radicals, are presented...
October 24, 2016: Physical Chemistry Chemical Physics: PCCP
Ganna Gryn'ova, Michelle L Coote, Clemence Corminboeuf
The electronic configuration of the molecule is the foundation of its structure and reactivity. The spin state is one of the key characteristics arising from the ordering of electrons within the molecule's set of orbitals. Organic molecules that have open-shell ground states and interesting physicochemical properties, particularly those influencing their spin alignment, are of immense interest within the up-and-coming field of molecular electronics. In this advanced review, we scrutinize various qualitative rules of orbital occupation and spin alignment, viz...
November 2015: Wiley Interdisciplinary Reviews. Computational Molecular Science
Anurag Mishra, Giorgio Pariani, Thomas Oerther, Markus Schwaiger, Gil Gregor Westmeyer
We introduce hyperpolarizable (13)C-labelled probes that identify multiple biologically important divalent metals via metal-specific chemical shifts. These features enable NMR measurements of calcium concentrations in human serum in the presence of magnesium. In addition, signal enhancement through Dynamic Nuclear Polarization (DNP) increases the sensitivity of metal detection to afford measuring micromolar concentrations of calcium as well as simultaneous multi-metal detection by chemical shift imaging. The hyperpolarizable (13)C-MRI sensors presented here enable sensitive NMR measurements and MR imaging of multiple divalent metals in opaque biological samples...
October 21, 2016: Analytical Chemistry
Ying Zhang, Xiaoyu Guo, Juan Dong
Cell polarization is commonly used for the regulation of stem cell asymmetric division in both animals and plants. Stomatal development in Arabidopsis, a process that produces breathing pores in the epidermis, requires asymmetric cell division to differentiate highly specialized guard cells while maintaining a stem cell population [1, 2]. The BREAKING OF ASYMMETRY IN THE STOMATAL LINEAGE (BASL) protein exhibits a polarized localization pattern in the cell and is required for differential cell fates resulting from asymmetric cell division [3]...
November 7, 2016: Current Biology: CB
Björn Corzilius
Correction for 'Theory of solid effect and cross effect dynamic nuclear polarization with half-integer high-spin metal polarizing agents in rotating solids' by Björn Corzilius et al., Phys. Chem. Chem. Phys., 2016, DOI: .
October 13, 2016: Physical Chemistry Chemical Physics: PCCP
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