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Chemistry
Interplay between Penicillin-binding proteins and SEDS proteins promotes bacterial cell wall synthesis
Feb 24, 2017   Scientific Reports
Leclercq S, Derouaux A, Olatunji S, Fraipont C, Egan AJ, Vollmer W, Breukink E, Terrak M
Interplay between Penicillin-binding proteins and SEDS proteins promotes bacterial cell wall synthesis
Feb 24, 2017
Scientific Reports
Bacteria utilize specialized multi-protein machineries to synthesize the essential peptidoglycan (PG) cell wall during growth and division. The divisome controls septal PG synthesis and separation of daughter cells. In E. coli, the lipid II transporter candidate FtsW is thought to work in concert with the PG synthases penicillin-binding proteins PBP3 and PBP1b. Yet, the exact molecular mechanisms of their function in complexes are largely unknown. We show that FtsW interacts with PBP1b and lipid II and that PBP1b, FtsW and PBP3 co-purify suggesting that they form a trimeric complex. We also show that the large loop between transmembrane helices 7 and 8 of FtsW is important for the interaction with PBP3. Moreover, we found that FtsW, but not the other flippase candidate MurJ, impairs lipid II polymerization and peptide cross-linking activities of PBP1b, and that PBP3 relieves these inhibitory effects. All together the results suggest that FtsW interacts with lipid II preventing its polymerization by PBP1b unless PBP3 is also present, indicating that PBP3 facilitates lipid II release and/or its transfer to PBP1b after transport across the cytoplasmic membrane. This tight regulatory mechanism is consistent with the cell's need to ensure appropriate use of the limited pool of lipid II.
PEGylated graphene oxide elicits strong immunological responses despite surface passivation
Feb 24, 2017   Nature Communications
Luo N, Weber JK, Wang S, Luan B, Yue H, Xi X, Du J, Yang Z, Wei W, Zhou R, Ma G
PEGylated graphene oxide elicits strong immunological responses despite surface passivation
Feb 24, 2017
Nature Communications
Engineered nanomaterials promise to transform medicine at the bio-nano interface. However, it is important to elucidate how synthetic nanomaterials interact with critical biological systems before such products can be safely utilized in humans. Past evidence suggests that polyethylene glycol-functionalized (PEGylated) nanomaterials are largely biocompatible and elicit less dramatic immune responses than their pristine counterparts. We here report results that contradict these findings. We find that PEGylated graphene oxide nanosheets (nGO-PEGs) stimulate potent cytokine responses in peritoneal macrophages, despite not being internalized. Atomistic molecular dynamics simulations support a mechanism by which nGO-PEGs preferentially adsorb onto and/or partially insert into cell membranes, thereby amplifying interactions with stimulatory surface receptors. Further experiments demonstrate that nGO-PEG indeed provokes cytokine secretion by enhancing integrin β
Low content Pt nanoparticles anchored on N-doped reduced graphene oxide with high and stable electrocatalytic activity for oxygen reduction reaction
Feb 24, 2017   Scientific Reports
Li Z, Gao Q, Zhang H, Tian W, Tan Y, Qian W, Liu Z
Low content Pt nanoparticles anchored on N-doped reduced graphene oxide with high and stable electrocatalytic activity for oxygen reduction reaction
Feb 24, 2017
Scientific Reports
A novel kind of Pt/N-rGO hybrid possessing of low content 5.31 wt.% Pt anchored on the surface of nitrogen doped reduced graphene oxide (N-rGO) evenly was prepared. The Pt has uniformed 2.8 nm diameter and exposed (111) crystal planes; meanwhile, the N works as the bridge between Pt and rGO with the Pt-N and N-C chemical bonds in Pt/N-rGO. The Pt/N-rGO material has a very high electrocatalytic activity in oxygen reduction reaction with the mass catalytic activity more than 1.5 times of the commercial Pt/C due to the synergistic catalytic effect of both N-doped carbon matrix and Pt nanoparticles. Moreover, the Pt/N-rGO exhibits an excellent stability with hardly loss (only 0.4%) after accelerated durability tests of 5000 cycles based on the stable Pt-N-C chemical bonds in Pt/N-rGO, which can prevent the detachment, dissolution, migration and aggregation of Pt nanoparticles on the matrix during the long-term cycling.
Thallium contamination in arable soils and vegetables around a steel plant-A newly-found significant source of Tl pollution in South China
Feb 24, 2017   Environmental Pollution (Barking, Essex : 1987)
Liu J, Luo X, Wang J, Xiao T, Chen D, Sheng G, Yin M, Lippold H, Wang C, Chen Y
Thallium contamination in arable soils and vegetables around a steel plant-A newly-found significant source of Tl pollution in South China
Feb 24, 2017
Environmental Pollution (Barking, Essex : 1987)
Thallium (Tl) is a highly toxic rare element. Severe Tl poisoning can cause neurological brain damage or even death. The present study was designed to investigate contents of Tl and other associated heavy metals in arable soils and twelve common vegetables cultivated around a steel plant in South China, a newly-found initiator of Tl pollution. Potential health risks of these metals to exposed population via consumption of vegetables were examined by calculating hazard quotients (HQ). The soils showed a significant contamination with Tl at a mean concentration of 1.34 mg/kg. The Tl levels in most vegetables (such as leaf lettuce, chard and pak choy) surpassed the maximum permissible level (0.5 mg/kg) according to the environmental quality standards for food in Germany. Vegetables like leaf lettuce, chard, pak choy, romaine lettuce and Indian beans all exhibited bioconcentration factors (BCF) and transfer factors (TF) for Tl higher than 1, indicating a hyperaccumulation of Tl in these plants. Although the elevated Tl levels in the vegetables at present will not immediately pose significant non-carcinogenic health risks to residents, it highlights the necessity of a permanent monitoring of Tl contamination in the steel-making areas.Copyright © 2017 Elsevier Ltd. All rights reserved.
Selectively Inducing Cancer Cell Death by Intracellular Enzyme-Instructed Self-Assembly (EISA) of Dipeptide Derivatives
Feb 24, 2017   Advanced Healthcare Materials
Li J, Shi J, Medina JE, Zhou J, Du X, Wang H, Yang C, Liu J, Yang Z, Dinulescu DM, Xu B
Selectively Inducing Cancer Cell Death by Intracellular Enzyme-Instructed Self-Assembly (EISA) of Dipeptide Derivatives
Feb 24, 2017
Advanced Healthcare Materials
Tight ligand-receptor binding, paradoxically, is a major root of drug resistance in cancer chemotherapy. To address this problem, instead of using conventional inhibitors or ligands, this paper focuses on the development of a novel process-enzyme-instructed self-assembly (EISA)-to kill cancer cells selectively. Here it is demonstrated that EISA as an intracellular process to generate nanofibrils of short peptides for selectively inhibiting cancer cell proliferation, including drug resistant ones. As the process that turns the non-self-assembling precursors into the self-assembling peptides upon the catalysis of carboxylesterases (CES), EISA occurs intracellularly to selectively inhibit a range of cancer cells that exhibit relatively high CES activities. More importantly, EISA inhibits drug resistant cancer cells (e.g., triple negative breast cancer cells (HCC1937) and platinum-resistant ovarian cells (SKOV3, A2780cis)). With the IC© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Regulation of photosensitisation processes by an RNA aptamer
Feb 24, 2017   Scientific Reports
Thoa TT, Minagawa N, Aigaki T, Ito Y, Uzawa T
Regulation of photosensitisation processes by an RNA aptamer
Feb 24, 2017
Scientific Reports
One of the most powerful attributes of proteins is their ability to bind to and modulate the chemistry of cofactors and prosthetic groups. Here, we demonstrated the ability of an artificial nucleic acid (an aptamer) to similarly control the functionality of a non-biological element. Specifically, we selected an RNA aptamer that binds tris(bipyridine) ruthenium (II), Ru(bpy)
Lattice-Matched Epitaxial Growth of Organic Heterostructures for Integrated Optoelectronic Application
Feb 24, 2017   Angewandte Chemie (International Ed. In English)
Zhang Y, Liao Q, Wang X, Yao J, Fu H
Lattice-Matched Epitaxial Growth of Organic Heterostructures for Integrated Optoelectronic Application
Feb 24, 2017
Angewandte Chemie (International Ed. In English)
Development of nanowire photonics requires integration of different nanowire components into highly ordered functional heterostructures. Herein, we report a sequential self-assembly of binary molecular components into branched nanowire heterostructures (BNHs) via lattice-matched epitaxial growth, in which the microribbon backbone of 2,5-Bis(5-tert-butyl-2-benzoxazolyl)thiophene (BBOT) functions as blue-emitting microlaser source to pump the nanowire branches of BODIPY. By constructing Au electrodes on both branch sides and measuring the photocurrent in them, we successfully realize the integration of an organic laser and a power meter in a single device. This work provides a new insight into the integration of 1D organic nanostructures into BNHs for realizing organic multifunctional photonic devices.© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Black Phosphorus Revisited: A Missing Metal-Free Elemental Photocatalyst for Visible Light Hydrogen Evolution
Feb 24, 2017   Advanced Materials (Deerfield Beach, Fla.)
Zhu X, Zhang T, Sun Z, Chen H, Guan J, Chen X, Ji H, Du P, Yang S
Black Phosphorus Revisited: A Missing Metal-Free Elemental Photocatalyst for Visible Light Hydrogen Evolution
Feb 24, 2017
Advanced Materials (Deerfield Beach, Fla.)
Metal-free elemental photocatalysts for hydrogen (H© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Non-Noble Metal-based Carbon Composites in Hydrogen Evolution Reaction: Fundamentals to Applications
Feb 24, 2017   Advanced Materials (Deerfield Beach, Fla.)
Wang J, Xu F, Jin H, Chen Y, Wang Y
Non-Noble Metal-based Carbon Composites in Hydrogen Evolution Reaction: Fundamentals to Applications
Feb 24, 2017
Advanced Materials (Deerfield Beach, Fla.)
Hydrogen has been hailed as a clean and sustainable alternative to finite fossil fuels in many energy systems. Water splitting is an important method for hydrogen production in high purity and large quantities. To accelerate the hydrogen evolution reaction (HER) rate, it is highly necessary to develop high efficiency catalysts and to select a proper electrolyte. Herein, the performances of non-noble metal-based carbon composites under various pH values (acid, alkaline and neutral media) for HER in terms of catalyst synthesis, structure and molecular design are systematically discussed. A detailed analysis of the structure-activity-pH correlations in the HER process gives an insight on the origin of the pH-dependence for HER, and provide guidance for future HER mechanism studies on non-noble metal-based carbon composites. Furthermore, this Review gives a fresh impetus to rational design of high-performance noble-metal-free composites catalysts and guide researchers to employ the established electrocatalysts in proper water electrolysis technologies.© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Intermetallic Nanocrystals: Syntheses and Catalytic Applications
Feb 24, 2017   Advanced Materials (Deerfield Beach, Fla.)
Yan Y, Du JS, Gilroy KD, Yang D, Xia Y, Zhang H
Intermetallic Nanocrystals: Syntheses and Catalytic Applications
Feb 24, 2017
Advanced Materials (Deerfield Beach, Fla.)
At the forefront of nanochemistry, there exists a research endeavor centered around intermetallic nanocrystals, which are unique in terms of long-range atomic ordering, well-defined stoichiometry, and controlled crystal structure. In contrast to alloy nanocrystals with no elemental ordering, it is challenging to synthesize intermetallic nanocrystals with a tight control over their size and shape. Here, recent progress in the synthesis of intermetallic nanocrystals with controllable sizes and well-defined shapes is highlighted. A simple analysis and some insights key to the selection of experimental conditions for generating intermetallic nanocrystals are presented, followed by examples to highlight the viable use of intermetallic nanocrystals as electrocatalysts or catalysts for various reactions, with a focus on the enhanced performance relative to their alloy counterparts that lack elemental ordering. Within the conclusion, perspectives on future developments in the context of synthetic control, structure-property relationships, and applications are discussed.© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Lysozyme encapsulated gold nanoclusters: effects of cluster synthesis on natural protein characteristics
Feb 24, 2017   Physical Chemistry Chemical Physics : PCCP
Russell BA, Jachimska B, Komorek P, Mulheran PA, Chen Y
Lysozyme encapsulated gold nanoclusters: effects of cluster synthesis on natural protein characteristics
Feb 24, 2017
Physical Chemistry Chemical Physics : PCCP
The study of gold nanoclusters (AuNCs) has seen much interest in recent history due to their unique fluorescence properties and environmentally friendly synthesis method using proteins as a growth scaffold. The differences in the physicochemical properties of lysozyme encapsulated AuNCs in comparison to natural lysozyme are characterised in order to determine the effects AuNCs have on natural protein behaviour. The hydrodynamic radius (dynamic light scattering), light absorbance (UV-Vis), electrophoretic mobility, relative density, dynamic viscosity, adsorption (quartz crystal microbalance) and circular dichroism (CD) characteristics of the molecules were studied. It was found that lysozyme forms small dimer/trimer aggregates upon the synthesis of AuNCs within the protein. The diameter of Ly-AuNCs was found to be 8.0 nm across a pH range of 2-11 indicating dimer formation, but larger aggregates with diameters >20 nm were formed between pH 3 and 6. The formation of larger aggregates limits the use of Ly-AuNCs as a fluorescent probe in this pH range. A large shift in the protein's isoelectric point was also observed, shifting from 11.0 to 4.0 upon AuNC synthesis. This resulted in major changes to the adsorption characteristics of lysozyme, observed using a QCM. A monolayer of 8 nm was seen for Ly-AuNCs at pH 4, offering further evidence that the proteins form small aggregates, unlike the natural monomer form of lysozyme. The adsorption of Ly-AuNCs was seen to decrease as pH was increased; this is in major contrast to the lysozyme adsorption behaviour. A decrease in the α-helix content was observed from 25% in natural lysozyme to 1% in Ly-AuNCs. This coincided with an increase in the β-sheet content after AuNC synthesis indicating that the natural structure of lysozyme was lost. The formation of protein dimers, the change in the protein surface charge from positive to negative, and secondary structure alteration caused by the AuNC synthesis must be considered before attempting to utilise Ly-AuNCs as in vivo probes.
Construction of Light-Harvesting Polymeric Vesicles in Aqueous Solution with Spatially Separated Donors and Acceptors
Feb 24, 2017   Macromolecular Rapid Communications
Li H, Liu Y, Huang T, Qi M, Ni Y, Wang J, Zheng Y, Zhou Y, Yan D
Construction of Light-Harvesting Polymeric Vesicles in Aqueous Solution with Spatially Separated Donors and Acceptors
Feb 24, 2017
Macromolecular Rapid Communications
This communication describes polymer vesicles self-assembled from hyperbranched polymers (branched polymersomes (BPs)) as scaffolds, conceptually mimicking the natural light-harvesting system in aqueous solution. The system is constructed with hydrophobic 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) as donors encapsulated in the hydrophobic hyperbranched cores of the vesicles and the hydrophilic Rhodamine B (RB) as acceptors incorporated on the surface of the vesicles through the cyclodextrin (CD)/RB host-guest interactions, through which the donors and acceptors are spatially separated to effectively avoid the self-quenching between donors. This vesicular light harvesting system has presented good energy transfer efficiency of about 80% in water, and can be used as the ink to write multiclolor letters. In addition, due to the giant dimension of BPs, the real-time fluorescent images of the vesicles under an optical microscope can be observed to prove the light-harvesting process. It is supposed that such a vesicular light-harvesting antenna can be used to construct artificial photosynthesis systems in the future.© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Silver Nanoparticle Generators: Silicon Dioxide Microspheres
Feb 24, 2017   Chemistry (Weinheim An Der Bergstrasse, Germany)
Liu Y, Li Y, Kang Y, Shen Q, Liu X, Zhou J
Silver Nanoparticle Generators: Silicon Dioxide Microspheres
Feb 24, 2017
Chemistry (Weinheim An Der Bergstrasse, Germany)
A green and simple approach has been developed here to in situ synthesize un-coated Ag nanoparticles (AgNPs) on the surface of thiol groups functionalized silica dioxide microspheres (TSMs) in the aqueous solution. As soon as the Ag+ ions attach onto the surface of TSMs in aqueous solution, nucleation and growth of AgNPs can complete within one minute spontaneously without other reducing agents or capping agents. The main reason is that the self-assembled silane-layer formed by mercaptosilane molecules could reduce the Ag0 formation energy, transport electrons efficiently, improve the nucleation density, and protect AgNPs against oxidation. Thus, the supported AgNPs present excellent chemical/photochemical stability in the air/solution. Meanwhile, the size of as-prepared AgNPs could be controlled by tuning the concentration of Ag+ ions. This process provides a general route to generate bare AgNPs on the surface of silica dioxide in situ, which might be extended to other materials and promising in developing novel methodologies for making the supported noble metal NPs with desired structure and properties.© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
High-bandwidth nanopore data analysis by using a modified hidden Markov model
Feb 24, 2017   Nanoscale
Zhang J, Liu X, Ying YL, Gu Z, Meng FN, Long YT
High-bandwidth nanopore data analysis by using a modified hidden Markov model
Feb 24, 2017
Nanoscale
Nanopore-based sensing is an emerging analytical technique with a number of important applications, including single-molecule detection and DNA sequencing. In this paper, we developed a Modified Hidden Markov Model (MHMM) to analyze directly the raw (unfiltered) nanopore current blockade data, which significantly reduced the filtering-induced distortion of the nanopore events. Traditionally, prior to further analysis, the measured nanopore data need to be pre-filtered to supress the strong noises. Nonetheless, this would result in the distortion of the shape of the blockade current especially for rapid translocations and bumping blockades. The HMM has been proved to be robust with respect to highly noisy data and thus ideally suitable for processing raw nanopore data directly. Unfortunately, its performance is somehow sensitive to the initial parameters usually preset arbitrarily. To overcome this problem, we use the Fuzzy c-Means (FCM) algorithm to initialize the HMM parameters automatically. Then we use the Viterbi training algorithm to optimize the HMM. Finally, the application results on both the simulated and experimental data are presented to demonstrate the practicability of the developed method for accurate detection of the nanopore current blockade events. The proposed method enables detection of the nanopore events at the highest bandwidth of the commercial instruments to extract the true useful information about the single molecules under analysis.
Phthalocyanine supported dinuclear Ln
Feb 24, 2017   Dalton Transactions (Cambridge, England : 2003)
Ge JY, Wang HY, Li J, Xie JZ, Song Y, Zuo JL
Phthalocyanine supported dinuclear Ln
Feb 24, 2017
Dalton Transactions (Cambridge, England : 2003)
Three dinuclear lanthanide complexes, [Ln
Molecular dynamics simulations reveal ligand-controlled positioning of a peripheral protein complex in membranes
Feb 24, 2017   Nature Communications
Ryckbosch SM, Wender PA, Pande VS
Molecular dynamics simulations reveal ligand-controlled positioning of a peripheral protein complex in membranes
Feb 24, 2017
Nature Communications
Bryostatin is in clinical trials for Alzheimer's disease, cancer, and HIV/AIDS eradication. It binds to protein kinase C competitively with diacylglycerol, the endogenous protein kinase C regulator, and plant-derived phorbol esters, but each ligand induces different activities. Determination of the structural origin for these differing activities by X-ray analysis has not succeeded due to difficulties in co-crystallizing protein kinase C with relevant ligands. More importantly, static, crystal-lattice bound complexes do not address the influence of the membrane on the structure and dynamics of membrane-associated proteins. To address this general problem, we performed long-timescale (400-500 µs aggregate) all-atom molecular dynamics simulations of protein kinase C-ligand-membrane complexes and observed that different protein kinase C activators differentially position the complex in the membrane due in part to their differing interactions with waters at the membrane inner leaf. These new findings enable new strategies for the design of simpler, more effective protein kinase C analogs and could also prove relevant to other peripheral protein complexes.Natural supplies of bryostatin, a compound in clinical trials for Alzheimer's disease, cancer, and HIV, are scarce. Here, the authors perform molecular dynamics simulations to understand how bryostatin interacts with membrane-bound protein kinase C, offering insights for the design of bryostatin analogs.
The cytotoxic
Feb 24, 2017   Science (New York, N.Y.)
Tayeb-Fligelman E, Tabachnikov O, Moshe A, Goldshmidt-Tran O, Sawaya MR, Coquelle N, Colletier JP, Landau M
The cytotoxic
Feb 24, 2017
Science (New York, N.Y.)
Amyloids are ordered protein aggregates, found in all kingdoms of life, and are involved in aggregation diseases as well as in physiological activities. In microbes, functional amyloids are often key virulence determinants, yet the structural basis for their activity remains elusive. We determined the fibril structure and function of the highly toxic, 22-residue phenol-soluble modulin α3 (PSMα3) peptide secreted by Copyright © 2017, American Association for the Advancement of Science.
Combining polyethylene and polypropylene: Enhanced performance with PE/
Feb 24, 2017   Science (New York, N.Y.)
Eagan JM, Xu J, Di Girolamo R, Thurber CM, Macosko CW, LaPointe AM, Bates FS, Coates GW
Combining polyethylene and polypropylene: Enhanced performance with PE/
Feb 24, 2017
Science (New York, N.Y.)
Polyethylene (PE) and isotactic polypropylene (Copyright © 2017, American Association for the Advancement of Science.
Therapeutic efficacy of novel microwave-sensitized mPEG-PLGA@ZrO
Feb 24, 2017   Nanoscale
Mao J, Tang S, Hong D, Zhao F, Niu M, Han X, Qi J, Bao H, Jiang Y, Fu C, Long D, Meng X, Su H
Therapeutic efficacy of novel microwave-sensitized mPEG-PLGA@ZrO
Feb 24, 2017
Nanoscale
The use of nanomaterials as drug delivery systems shows good effects in treating tumors. However, the effective dose of drugs targeted to tumor tissues is very low because of the effect of the reticuloendothelial system (RES) in removing such foreign substances. In order to eliminate the RES effect, we developed mPEG-PLGA@ZrO
Hydrophilicities of amylose and natural cellulose are regulated by the linkage between sugar rings
Feb 24, 2017   Nanoscale
Bao Y, Xu D, Qian L, Zhao L, Lu ZY, Cui S
Hydrophilicities of amylose and natural cellulose are regulated by the linkage between sugar rings
Feb 24, 2017
Nanoscale
Comparative studies of single molecule force spectroscopy and molecular dynamics simulations indicate that natural cellulose is more hydrophobic than amylose at the single-chain level, implying that the hydrophobicities of these polymeric isomers are regulated by only one parameter in the chains, the linkage between the sugar rings.
A general three-step one-pot synthesis of novel (E)-6-chloro-2-(aryl/hetarylvinyl)quinoline-3-carboxylic acids
Feb 24, 2017   Molecular Diversity
Li Y, Wang Y, Zou H
A general three-step one-pot synthesis of novel (E)-6-chloro-2-(aryl/hetarylvinyl)quinoline-3-carboxylic acids
Feb 24, 2017
Molecular Diversity
In this work, a facile and general three-step one-pot synthesis of structurally new (E)-6-chloro-2-(aryl/hetarylvinyl)quinoline-3-carboxylic acid derivatives has been achieved from easily available ethyl 6-chloro-2-(chloromethyl) quinoline-3-carboxylate and aromatic or heteroaromatic aldehydes. This strategy features simple one-pot operation, tolerance of a wide range of substituents, and good yields. Moreover, these newly synthesized compounds belong to a new class of quinoline derivatives and could be good candidates for the development of more complex quinoline compounds for use in medicinal chemistry.
Effects on heavy metal accumulation in freshwater fishes: species, tissues, and sizes
Feb 24, 2017   Environmental Science And Pollution Research International
Jia Y, Wang L, Qu Z, Wang C, Yang Z
Effects on heavy metal accumulation in freshwater fishes: species, tissues, and sizes
Feb 24, 2017
Environmental Science And Pollution Research International
Three fish species (Carassius auratus, Pelteobagrus fulvidraco, and Squaliobarbus curriculus) were collected from Xiang River near Changsha City, Southern China. The concentrations of heavy metals including arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), and zinc (Zn) in the muscle, gill, and liver of three species were determined by the inductively coupled plasma mass spectrometry method. One-way analysis of variance (ANOVA) was introduced to determine the significant variations (p 
Prasugrel suppresses development of lithium-induced nephrogenic diabetes insipidus in mice
Feb 24, 2017   Purinergic Signalling
Zhang Y, Peti-Peterdi J, Brandes AU, Riquier-Brison A, Carlson NG, Müller CE, Ecelbarger CM, Kishore BK
Enhanced production of camptothecin and biological preparation of N
Feb 24, 2017   Applied Microbiology And Biotechnology
Yang Y, Pu X, Qu X, Chen F, Zhang G, Luo Y
Enhanced production of camptothecin and biological preparation of N
Feb 24, 2017
Applied Microbiology And Biotechnology
The Camptotheca acuminata cell suspension cultures were established to produce the well-known antitumor monoterpene indole alkaloid camptothecin (CAM). Most CAM was present in the broth of the C. acuminata cell suspension cultures. The CAM production was evidenced to be attenuated when the C. acuminata cell suspension cultures were continuously subcultured and grown under identical axenic conditions. A practical cryopreservation and recovery procedure was established to maintain the C. acuminata cell suspension cultures. Biotic and abiotic elicitors were administrated to the C. acuminata cell suspension cultures to restore and enhance CAM production. Of them, sorbitol, a well-known hyperosmotic stressor, was proven to be the most effective elicitor that stimulates a ∼500-fold increase of CAM production. The committed biosynthetic precursors of CAM, tryptamine and secologanin, were feed to the C. acuminata cell suspension cultures and the CAM production is not remarkably increased. However, N
The [4Fe4S] cluster of human DNA primase functions as a redox switch using DNA charge transport
Feb 24, 2017   Science (New York, N.Y.)
O'Brien E, Holt ME, Thompson MK, Salay LE, Ehlinger AC, Chazin WJ, Barton JK
The [4Fe4S] cluster of human DNA primase functions as a redox switch using DNA charge transport
Feb 24, 2017
Science (New York, N.Y.)
DNA charge transport chemistry offers a means of long-range, rapid redox signaling. We demonstrate that the [4Fe4S] cluster in human DNA primase can make use of this chemistry to coordinate the first steps of DNA synthesis. Using DNA electrochemistry, we found that a change in oxidation state of the [4Fe4S] cluster acts as a switch for DNA binding. Single-atom mutations that inhibit this charge transfer hinder primase initiation without affecting primase structure or polymerization. Generating a single base mismatch in the growing primer duplex, which attenuates DNA charge transport, inhibits primer truncation. Thus, redox signaling by [4Fe4S] clusters using DNA charge transport regulates primase binding to DNA and illustrates chemistry that may efficiently drive substrate handoff between polymerases during DNA replication.Copyright © 2017, American Association for the Advancement of Science.

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