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Michael J Mitsch, George C diCenzo, Alison Cowie, Turlough M Finan
Symbiotic nitrogen fixation (SNF) is an energetically expensive process performed by bacteria during endosymbiotic relationships with plants. The bacteria require the plant to provide a carbon source for generation of reductant to power SNF. While C4-dicarboxylates (succinate, fumarate, malate) appear to be the primary, if not sole, carbon source provided to the bacteria, the contribution of each C4-dicarboxylate is not known. We address this issue using a genetic and systems-level analyses. Expression of a malate specific transporter (MaeP) in Sinorhizobium meliloti Rm1021 dct mutants unable to transport C4-dicarboxylates resulted in malate import rates up to 30% that of wild type...
September 15, 2017: Applied and Environmental Microbiology
Justin J Evans, Chengfeng Xiao, R Meldrum Robertson
During anoxia, proper energy maintenance is essential in order to maintain neural operation. Starvation activates AMP-activated protein kinase (AMPK), an evolutionarily conserved indicator of cellular energy status, in a cascade which modulates ATP production and consumption. We investigated the role of energetic status on anoxia tolerance in Drosophila and discovered that starvation or AMPK activation increases the speed of locomotor recovery from an anoxic coma. Using temporal and spatial genetic targeting we found that AMPK in the fat body contributes to starvation-induced fast locomotor recovery, whereas, under fed conditions, disrupting AMPK in oenocytes prolongs recovery...
September 12, 2017: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
Katja Biswas
A computational method is presented which is capable to obtain low lying energy structures of topological amorphous systems. The method merges a differential mutation genetic algorithm with simulated annealing. This is done by incorporating a thermal selection criterion, which makes it possible to reliably obtain low lying minima with just a small population size and is suitable for multimodal structural optimization. The method is tested on the structural optimization of amorphous graphene from unbiased atomic starting configurations...
September 14, 2017: Journal of Chemical Physics
Silvia Vidali, Sepideh Aminzadeh-Gohari, René Günther Feichtinger, Renaud Vatrinet, Andreas Koller, Felix Locker, Tricia Rutherford, Maura O'Donnell, Andrea Stöger-Kleiber, Bridget Lambert, Thomas Klaus Felder, Wolfgang Sperl, Barbara Kofler
The ketogenic diet (KD), a high-fat low-carbohydrate diet, has shown some efficacy in the treatment of certain types of tumors such as brain tumors and neuroblastoma. These tumors are characterized by the Warburg effect. Because renal cell carcinoma (RCC) presents similar energetic features as neuroblastoma, KD might also be effective in the treatment of RCC. To test this, we established xenografts with RCC 786-O cells in CD-1 nu/nu mice and then randomized them to a control diet or to KDs with different triglyceride contents...
August 22, 2017: Oncotarget
Baptiste Panthu, Théophile Ohlmann, Johan Perrier, Uwe Schlattner, Pierre Jalinot, Bénédicte Elena-Herrmann, Gilles J P Rautureau
A counter-intuitive cell-free protein synthesis (CFPS) strategy, based on reducing the ribosomal fraction in rabbit reticulocyte lysate (RRL), triggers the development of hybrid systems composed of RRL ribosome-free supernatant complemented with ribosomes from different mammalian cell-types. Hybrid RRL systems maintain translational properties of the original ribosome cell types, and deliver protein expression levels similar to RRL. Here, we show that persistent ribosome-associated metabolic activity consuming ATP is a major obstacle for maximal protein yield...
September 15, 2017: ACS Synthetic Biology
D N Papadopoulos, P Ramirez, K Genevrier, L Ranc, N Lebas, A Pellegrina, C Le Blanc, P Monot, L Martin, J P Zou, F Mathieu, P Audebert, P Georges, F Druon
Applications using multi-PW lasers necessitate high temporal pulse quality with a tremendous contrast ratio (CR). The first crucial prerequisite to achieve multi-PW peak power is the generation of ultrashort pulses with good spectral phase quality. Second, to avoid any deleterious pre-ionization effect on targets, nanosecond contrast better than 10(12) is also targeted. In the framework of the Apollon 10 PW French laser program, we present a high-contrast 10 fs front-end design study to inject highly energetic Ti:sapphire PW lasers...
September 15, 2017: Optics Letters
Aurelio Garcia-Valenzuela, Carmen Lopez-Santos, Rafael Alvarez, Victor J Rico, Jose Cotrino, Agustin Rodriguez Gonzalez-Elipe, Alberto Palmero
In this work we analyze a phenomenon that takes place when growing magnetron sputtered porous/compact multilayer systems by alternating the oblique angle and the classical configuration geometries. We show that the compact layers develop numerous fissures rooted in the porous structures of the film below, in a phenomenon that amplifies when increasing the number of stacked layers. We demonstrate that these fissures emerge during growth due to the high roughness of the porous layers and the coarsening of a discontinuous interfacial region...
September 15, 2017: Nanotechnology
San Hadži, Andrej Mernik, Črtomir Podlipnik, Remy Loris, Jurij Lah
Many intrinsically disordered proteins (IDP) that fold upon binding retain conformational heterogeneity in IDP-target complexes. The thermodynamics of such fuzzy interactions is poorly understood. Here we introduce a thermodynamic framework, based on analysis of ITC and CD spectroscopy data, that provides experimental description of IDP association in terms of folding and binding contributions which can be predicted using sequence folding propensities and molecular modeling. We show how IDP can modulate the entropy and enthalpy by adapting their bound-state structural ensemble to achieve optimal binding...
September 15, 2017: Angewandte Chemie
Joelma M Nasareth, Carolina M Fraga, Nayana F Lima, Guaraciara A Picanço, Tatiane L Costa, Ruy S Lino-Junior, Marina Clare Vinaud
Taenia crassiceps cysticerci are used as experimental model to study the host-parasite relationship and treatment of cysticercosis. One of the described mode of actions of nitazoxanide (NTZ) is to block the pyruvate ferredoxine oxidoreductase (PFOR) enzyme which is an essential enzyme to the parasite metabolism. The aim of this study was to determine the in vivo influence of one dosage of NTZ on the energetic metabolism of T. crassiceps cysticerci. Thirty days after the intraperitoneal inoculation of T. crassiceps cysticerci, BALB/c mice were orally treated with 7...
September 15, 2017: Parasitology Research
Zhenlong Zhao, Mruthunjaya Uddi, Nikolai Tsvetkov, Bilge Yildiz, Ahmed F Ghoniem
CO2 splitting via thermo-chemical or reactive redox has emerged as a novel and promising carbon-neutral energy solution. Its performance depends critically on the properties of the oxygen carriers (OC). Ceria is recognized as one of the most promising OC candidates, because of its fast chemistry, high ionic diffusivity, and large oxygen storage capacity. The fundamental surface ion-incorporation pathways, along with the role of surface defects and the adsorbates remain largely unknown. This study presents a detailed kinetics study of CO2 splitting using CeO2 and Ce0...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Sramana Kundu, Vaibhav S Prabhudesai, E Krishnakumar
We demonstrate the efficient formation of carbon-nitrogen bonds starting from CH4 and NH3 on a metal surface at cryogenic temperatures. Electrons in the energy range of 1-90 eV are used to initiate chemical reactions in mixed molecular films of CH4 and NH3 at ∼15 K, and the products are detected by performing temperature programmed desorption (TPD). Extensive dehydrogenation occurs at all energies giving the products CH2NH and HCN in preference to CH3NH2. This is likely to do with the energetics of the reactions and the subsequent stability of these species in the condensed film...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Frederico V Prudente, Jorge M C Marques, Francisco B Pereira
A new analytical potential for Li(+)Ar2 including three-body interactions has been modeled by employing ab initio energies that were calculated within the CCSD(T) framework and a quadruple-zeta basis-set (i.e., cc-pVQZ for lithium and aug-cc-pVQZ for argon) and, then, corrected for the basis-set superposition error (BSSE) with the counterpoise method. Departing from this function, we have constructed the potential energy surface for Li(+)Arn clusters by summing over all two-body and three-body terms. We have employed our evolutionary algorithm (EA) to perform a global geometry optimization that allows for the study of a Li(+) ion microsolvated with argon atoms...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
Nathan D Bade, Randall D Kamien, Richard K Assoian, Kathleen J Stebe
In vivo, cells respond to a host of physical cues ranging from substrate stiffness to the organization of micro- and nanoscale fibrous networks. We show that macroscale substrates with radii of curvature from tens to hundreds of micrometers influence cell alignment. In a model system of fibroblasts, isolated cells aligned strongly in the axial direction on cylinders with radii similar to the cell length and more weakly on cylinders of much larger radius. Isolated vascular smooth muscle cells did not align as effectively as fibroblasts...
September 2017: Science Advances
Christine Arhant, Andrea Martina Beetz, Josef Troxler
In children up to 6 years, interactions such as interfering with the dog's resources and also benign behaviors (e.g., petting) commonly precede a bite incident with the family dog. Therefore, the aim of the present study was to explore the development of everyday interactions between children up to 6 years and their family dogs and whether parents' attitudes to supervision are related to those interactions. Additionally, we investigated whether behavior of dogs that had lived in the family for longer than the child differed from those that grew up with children...
2017: Frontiers in Veterinary Science
Oliver D Caspari, Moritz T Meyer, Dimitri Tolleter, Tyler M Wittkopp, Nik J Cunniffe, Tracy Lawson, Arthur R Grossman, Howard Griffiths
The pyrenoid of the unicellular green alga Chlamydomonas reinhardtii is a microcompartment situated in the centre of the cup-shaped chloroplast, containing up to 90% of cellular Rubisco. Traversed by a network of dense, knotted thylakoid tubules, the pyrenoid has been proposed to influence thylakoid biogenesis and ultrastructure. Mutants that are unable to assemble a pyrenoid matrix, due to expressing a vascular plant version of the Rubisco small subunit, exhibit severe growth and photosynthetic defects and have an ineffective carbon-concentrating mechanism (CCM)...
June 1, 2017: Journal of Experimental Botany
Yongxing Tang, Dheeraj Kumar, Jean'ne M Shreeve
The key to successfully design high-performance and insensi-tive energetic compounds for practical applications is through adjusting the molecular organization including both fuel and oxidizer. Now a superior hydrogen-free 5/6/5 fused ring energet-ic material, 1,2,9,10-tetranitrodipyrazolo[1,5-d:5',1'-f][1,2,3,4]tetrazine (6) obtained from 4,4',5,5'-tetranitro-2H,2'H-3,3'-bipyrazole (4) by N-amination and N-azo coupling reac-tions is described. The structures of 5 and 6 were confirmed by single crystal X-ray diffraction measurements...
September 14, 2017: Journal of the American Chemical Society
Christopher Lockhart, Dmitri K Klimov
Using isobaric-isothermal all-atom replica-exchange molecular dynamics (REMD) simulations, we investigated the equilibrium binding of Abeta10-40 monomers to the zwitterionic dimyristoylphosphatidylcholine (DMPC) bilayer containing cholesterol. Our previous REMD simulations, which studied binding of the same peptide to the cholesterol-free DMPC bilayer, served as a control, against which we measured the impact of cholesterol. Our findings are as follows. First, addition of cholesterol to the DMPC bilayer partially expels the Abeta peptide from the hydrophobic core and promotes its binding to bilayer polar headgroups...
September 14, 2017: Journal of Chemical Information and Modeling
Matthew McDougall, Olga Francisco, Candice Viddal, Roy Roshko, Markus Meier, Jörg Stetefeld
Elemental sulfur exists primarily as an S80 ring and serves as terminal electron acceptor for a variety of Sulfur-fermenting bacteria. Hyperthermophilic archaea from black smoker vents are an exciting research tool to advance our knowledge of sulfur respiration under extreme conditions. Here we use a hybrid method approach to demonstrate that the proteinaceous cavities of the S-layer nanotube of the hyperthermophilic archaeon Staphylothermus marinus act as a storage reservoir for cyclo-octasulfur S(8) . Fully atomistic molecular dynamics simulations were performed and the method of Multi-Configurational Thermodynamic Integration was employed to compute the absolute free energy for transferring a ring of elemental sulfur S8 from an aqueous bath into the largest hydrophobic cavity of a fragment of archaeal tetrabrachion...
September 14, 2017: Proteins
Jindal Garima, Arieh Warshel
Understanding the origin of the catalytic power of enzymes has both conceptual and practical importance. One of the most important finding from computational studies of enzyme catalysis is that a major part of the catalytic power is due to the preorganization of the enzyme active site. Unfortunately, misunderstanding of the non trivial preorganization idea lead some (e.g. Ref (1) ) to assume that it does not consider the effect of the protein residues. This major confusion reflects a misunderstanding of the statement that the interaction energy of the enzyme group and the transition state is similar to the corresponding interaction between the water molecules and the TS, and that the catalysis is due to the reorganization free energy of the water molecules...
September 14, 2017: Proteins
Kristina L Paxton, Frank R Moore
The phases of the annual cycle for migratory species are inextricably linked. Yet, less than five percent of ecological studies examine seasonal interactions. In this study, we utilized stable hydrogen isotopes to geographically link individual black-and-white warblers (Mniotilta varia) captured during spring migration with breeding destinations to understand a migrant's stopover strategy in the context of other phases of the annual cycle. We found that stopover strategy is not only a function of a bird's current energetic state, but also the distance remaining to breeding destination and a bird's time-schedule, which has previously been linked to habitat conditions experienced in the preceding phase of the annual cycle...
September 2017: Ecology and Evolution
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