Sample records for factor complex formation

  1. SEPALLATA3: the 'glue' for MADS box transcription factor complex formation

    PubMed Central

    Immink, Richard GH; Tonaco, Isabella AN; de Folter, Stefan; Shchennikova, Anna; van Dijk, Aalt DJ; Busscher-Lange, Jacqueline; Borst, Jan W; Angenent, Gerco C

    2009-01-01

    Background Plant MADS box proteins play important roles in a plethora of developmental processes. In order to regulate specific sets of target genes, MADS box proteins dimerize and are thought to assemble into multimeric complexes. In this study a large-scale yeast three-hybrid screen is utilized to provide insight into the higher-order complex formation capacity of the Arabidopsis MADS box family. SEPALLATA3 (SEP3) has been shown to mediate complex formation and, therefore, special attention is paid to this factor in this study. Results In total, 106 multimeric complexes were identified; in more than half of these at least one SEP protein was present. Besides the known complexes involved in determining floral organ identity, various complexes consisting of combinations of proteins known to play a role in floral organ identity specification, and flowering time determination were discovered. The capacity to form this latter type of complex suggests that homeotic factors play essential roles in down-regulation of the MADS box genes involved in floral timing in the flower via negative auto-regulatory loops. Furthermore, various novel complexes were identified that may be important for the direct regulation of the floral transition process. A subsequent detailed analysis of the APETALA3, PISTILLATA, and SEP3 proteins in living plant cells suggests the formation of a multimeric complex in vivo. Conclusions Overall, these results provide strong indications that higher-order complex formation is a general and essential molecular mechanism for plant MADS box protein functioning and attribute a pivotal role to the SEP3 'glue' protein in mediating multimerization. PMID:19243611

  2. Elongation factor Ts directly facilitates the formation and disassembly of the Escherichia coli elongation factor Tu·GTP·aminoacyl-tRNA ternary complex.

    PubMed

    Burnett, Benjamin J; Altman, Roger B; Ferrao, Ryan; Alejo, Jose L; Kaur, Navdep; Kanji, Joshua; Blanchard, Scott C

    2013-05-10

    Aminoacyl-tRNA (aa-tRNA) enters the ribosome in a ternary complex with the G-protein elongation factor Tu (EF-Tu) and GTP. EF-Tu·GTP·aa-tRNA ternary complex formation and decay rates are accelerated in the presence of the nucleotide exchange factor elongation factor Ts (EF-Ts). EF-Ts directly facilitates the formation and disassociation of ternary complex. This system demonstrates a novel function of EF-Ts. Aminoacyl-tRNA enters the translating ribosome in a ternary complex with elongation factor Tu (EF-Tu) and GTP. Here, we describe bulk steady state and pre-steady state fluorescence methods that enabled us to quantitatively explore the kinetic features of Escherichia coli ternary complex formation and decay. The data obtained suggest that both processes are controlled by a nucleotide-dependent, rate-determining conformational change in EF-Tu. Unexpectedly, we found that this conformational change is accelerated by elongation factor Ts (EF-Ts), the guanosine nucleotide exchange factor for EF-Tu. Notably, EF-Ts attenuates the affinity of EF-Tu for GTP and destabilizes ternary complex in the presence of non-hydrolyzable GTP analogs. These results suggest that EF-Ts serves an unanticipated role in the cell of actively regulating the abundance and stability of ternary complex in a manner that contributes to rapid and faithful protein synthesis.

  3. Elongation Factor Ts Directly Facilitates the Formation and Disassembly of the Escherichia coli Elongation Factor Tu·GTP·Aminoacyl-tRNA Ternary Complex*

    PubMed Central

    Burnett, Benjamin J.; Altman, Roger B.; Ferrao, Ryan; Alejo, Jose L.; Kaur, Navdep; Kanji, Joshua; Blanchard, Scott C.

    2013-01-01

    Aminoacyl-tRNA enters the translating ribosome in a ternary complex with elongation factor Tu (EF-Tu) and GTP. Here, we describe bulk steady state and pre-steady state fluorescence methods that enabled us to quantitatively explore the kinetic features of Escherichia coli ternary complex formation and decay. The data obtained suggest that both processes are controlled by a nucleotide-dependent, rate-determining conformational change in EF-Tu. Unexpectedly, we found that this conformational change is accelerated by elongation factor Ts (EF-Ts), the guanosine nucleotide exchange factor for EF-Tu. Notably, EF-Ts attenuates the affinity of EF-Tu for GTP and destabilizes ternary complex in the presence of non-hydrolyzable GTP analogs. These results suggest that EF-Ts serves an unanticipated role in the cell of actively regulating the abundance and stability of ternary complex in a manner that contributes to rapid and faithful protein synthesis. PMID:23539628

  4. Bacterial formate hydrogenlyase complex.

    PubMed

    McDowall, Jennifer S; Murphy, Bonnie J; Haumann, Michael; Palmer, Tracy; Armstrong, Fraser A; Sargent, Frank

    2014-09-23

    Under anaerobic conditions, Escherichia coli can carry out a mixed-acid fermentation that ultimately produces molecular hydrogen. The enzyme directly responsible for hydrogen production is the membrane-bound formate hydrogenlyase (FHL) complex, which links formate oxidation to proton reduction and has evolutionary links to Complex I, the NADH:quinone oxidoreductase. Although the genetics, maturation, and some biochemistry of FHL are understood, the protein complex has never been isolated in an intact form to allow biochemical analysis. In this work, genetic tools are reported that allow the facile isolation of FHL in a single chromatographic step. The core complex is shown to comprise HycE (a [NiFe] hydrogenase component termed Hyd-3), FdhF (the molybdenum-dependent formate dehydrogenase-H), and three iron-sulfur proteins: HycB, HycF, and HycG. A proportion of this core complex remains associated with HycC and HycD, which are polytopic integral membrane proteins believed to anchor the core complex to the cytoplasmic side of the membrane. As isolated, the FHL complex retains formate hydrogenlyase activity in vitro. Protein film electrochemistry experiments on Hyd-3 demonstrate that it has a unique ability among [NiFe] hydrogenases to catalyze production of H2 even at high partial pressures of H2. Understanding and harnessing the activity of the FHL complex is critical to advancing future biohydrogen research efforts.

  5. Complex organic molecules and star formation

    NASA Astrophysics Data System (ADS)

    Bacmann, A.; Faure, A.

    2014-12-01

    Star forming regions are characterised by the presence of a wealth of chemical species. For the past two to three decades, ever more complex organic species have been detected in the hot cores of protostars. The evolution of these molecules in the course of the star forming process is still uncertain, but it is likely that they are partially incorporated into protoplanetary disks and then into planetesimals and the small bodies of planetary systems. The complex organic molecules seen in star forming regions are particularly interesting since they probably make up building blocks for prebiotic chemistry. Recently we showed that these species were also present in the cold gas in prestellar cores, which represent the very first stages of star formation. These detections question the models which were until now accepted to account for the presence of complex organic molecules in star forming regions. In this article, we shortly review our current understanding of complex organic molecule formation in the early stages of star formation, in hot and cold cores alike and present new results on the formation of their likely precursor radicals.

  6. Monkeypox Virus Host Factor Screen Using Haploid Cells Identifies Essential Role of GARP Complex in Extracellular Virus Formation.

    PubMed

    Realegeno, Susan; Puschnik, Andreas S; Kumar, Amrita; Goldsmith, Cynthia; Burgado, Jillybeth; Sambhara, Suryaprakash; Olson, Victoria A; Carroll, Darin; Damon, Inger; Hirata, Tetsuya; Kinoshita, Taroh; Carette, Jan E; Satheshkumar, Panayampalli Subbian

    2017-06-01

    Monkeypox virus (MPXV) is a human pathogen that is a member of the Orthopoxvirus genus, which includes Vaccinia virus and Variola virus (the causative agent of smallpox). Human monkeypox is considered an emerging zoonotic infectious disease. To identify host factors required for MPXV infection, we performed a genome-wide insertional mutagenesis screen in human haploid cells. The screen revealed several candidate genes, including those involved in Golgi trafficking, glycosaminoglycan biosynthesis, and glycosylphosphatidylinositol (GPI)-anchor biosynthesis. We validated the role of a set of vacuolar protein sorting (VPS) genes during infection, VPS51 to VPS54 (VPS51-54), which comprise the Golgi-associated retrograde protein (GARP) complex. The GARP complex is a tethering complex involved in retrograde transport of endosomes to the trans -Golgi apparatus. Our data demonstrate that VPS52 and VPS54 were dispensable for mature virion (MV) production but were required for extracellular virus (EV) formation. For comparison, a known antiviral compound, ST-246, was used in our experiments, demonstrating that EV titers in VPS52 and VPS54 knockout (KO) cells were comparable to levels exhibited by ST-246-treated wild-type cells. Confocal microscopy was used to examine actin tail formation, one of the viral egress mechanisms for cell-to-cell dissemination, and revealed an absence of actin tails in VPS52KO- or VPS54KO-infected cells. Further evaluation of these cells by electron microscopy demonstrated a decrease in levels of wrapped viruses (WVs) compared to those seen with the wild-type control. Collectively, our data demonstrate the role of GARP complex genes in double-membrane wrapping of MVs necessary for EV formation, implicating the host endosomal trafficking pathway in orthopoxvirus infection. IMPORTANCE Human monkeypox is an emerging zoonotic infectious disease caused by Monkeypox virus (MPXV). Of the two MPXV clades, the Congo Basin strain is associated with severe

  7. Nanoparticle-protein complexes mimicking corona formation in ocular environment.

    PubMed

    Jo, Dong Hyun; Kim, Jin Hyoung; Son, Jin Gyeong; Dan, Ki Soon; Song, Sang Hoon; Lee, Tae Geol; Kim, Jeong Hun

    2016-12-01

    Nanoparticles adsorb biomolecules to form corona upon entering the biological environment. In this study, tissue-specific corona formation is provided as a way of controlling protein interaction with nanoparticles in vivo. In the vitreous, the composition of the corona was determined by the electrostatic and hydrophobic properties of the associated proteins, regardless of the material (gold and silica) or size (20- and 100-nm diameter) of the nanoparticles. To control protein adsorption, we pre-incubate 20-nm gold nanoparticles with 5 selectively enriched proteins from the corona, formed in the vitreous, to produce nanoparticle-protein complexes. Compared to bare nanoparticles, nanoparticle-protein complexes demonstrate improved binding to vascular endothelial growth factor (VEGF) in the vitreous. Furthermore, nanoparticle-protein complexes retain in vitro anti-angiogenic properties of bare nanoparticles. In particular, priming the nanoparticles (gold and silica) with tissue-specific corona proteins allows nanoparticle-protein complexes to exert better in vivo therapeutic effects by higher binding to VEGF than bare nanoparticles. These results suggest that controlled corona formation that mimics in vivo processes may be useful in the therapeutic use of nanomaterials in local environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Study of the formation of soluble complexes of sodium caseinate and xanthan in solution.

    PubMed

    Bouhannache, Bouchra; HadjSadok, Abdelkader; Touabet, Abdelkrim

    2017-09-01

    The main objective of this work was to determinate the optimum conditions for the formation of soluble complexes between sodium caseinate and xanthan in solution at neutral pH, in the presence of the NaCl. The study of the influence of the concentrations of these three substances showed that salt was the most influent factor. It worsens the thermodynamic incompatibility of the two biopolymers in solution, when they are present at large amounts. However, it contributes to soluble complexes formation, when sodium caseinate concentration is below 5.5%. In this case, gels with enhanced rheological properties were obtained. Infrared spectroscopy confirmed that the complexes formation within these gels involves hydrophobic interactions. On the other hand, dynamic light scattering revealed that dilution cause their dissociation. These soluble complexes are promising ingredients to ensure new texturing properties.

  9. Combined EXAFS Spectroscopic and Quantum Chemical Study on the Complex Formation of Am(III) with Formate.

    PubMed

    Fröhlich, Daniel R; Kremleva, Alena; Rossberg, André; Skerencak-Frech, Andrej; Koke, Carsten; Krüger, Sven; Rösch, Notker; Panak, Petra J

    2017-06-19

    The complexation of Am(III) with formate in aqueous solution is studied as a function of the pH value using a combination of extended X-ray absorption fine structure (EXAFS) spectroscopy, iterative transformation factor analysis (ITFA), and quantum chemical calculations. The Am L III -edge EXAFS spectra are analyzed to determine the molecular structure (coordination numbers; Am-O and Am-C distances) of the formed Am(III)-formate species and to track the shift of the Am(III) speciation with increasing pH. The experimental data are compared to predictions from density functional calculations. The results indicate that formate binds to Am(III) in a monodentate fashion, in agreement with crystal structures of lanthanide formates. Furthermore, the investigations are complemented by thermodynamic speciation calculations to verify further the results obtained.

  10. The significance of ACTH for the process of formation of complex heparin compounds in the blood during immobilization stress

    NASA Technical Reports Server (NTRS)

    Kudryashov, B. A.; Shapiro, F. B.; Lomovskaya, F. B.; Lyapina, L. A.

    1979-01-01

    Adrenocorticotropin (ACTH) was administered to rats at different times following adrenalectomy. Adrenocorticotropin caused a significant increase in the formation of heparin complexes even in the absence of stress factor. When ACTH secretion is blocked, immobilization stress is not accompanied by an increase in the process of complex formation. The effect of ACTH on the formation of heparin complexes was mediated through its stimulation of the adrenal cortex.

  11. STAR FORMATION ACROSS THE W3 COMPLEX

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Román-Zúñiga, Carlos G.; Ybarra, Jason E.; Tapia, Mauricio

    We present a multi-wavelength analysis of the history of star formation in the W3 complex. Using deep, near-infrared ground-based images combined with images obtained with Spitzer and Chandra observatories, we identified and classified young embedded sources. We identified the principal clusters in the complex and determined their structure and extension. We constructed extinction-limited samples for five principal clusters and constructed K-band luminosity functions that we compare with those of artificial clusters with varying ages. This analysis provided mean ages and possible age spreads for the clusters. We found that IC 1795, the centermost cluster of the complex, still hosts amore » large fraction of young sources with circumstellar disks. This indicates that star formation was active in IC 1795 as recently as 2 Myr ago, simultaneous to the star-forming activity in the flanking embedded clusters, W3-Main and W3(OH). A comparison with carbon monoxide emission maps indicates strong velocity gradients in the gas clumps hosting W3-Main and W3(OH) and shows small receding clumps of gas at IC 1795, suggestive of rapid gas removal (faster than the T Tauri timescale) in the cluster-forming regions. We discuss one possible scenario for the progression of cluster formation in the W3 complex. We propose that early processes of gas collapse in the main structure of the complex could have defined the progression of cluster formation across the complex with relatively small age differences from one group to another. However, triggering effects could act as catalysts for enhanced efficiency of formation at a local level, in agreement with previous studies.« less

  12. Function of the growth-regulated transcription initiation factor TIF-IA in initiation complex formation at the murine ribosomal gene promoter.

    PubMed

    Schnapp, A; Schnapp, G; Erny, B; Grummt, I

    1993-11-01

    Alterations in the rate of cell proliferation are accompanied by changes in the transcription of rRNA genes. In mammals, this growth-dependent regulation of transcription of genes coding for rRNA (rDNA) is due to reduction of the amount or activity of an essential transcription factor, called TIF-IA. Extracts prepared from quiescent cells lack this factor activity and, therefore, are transcriptionally inactive. We have purified TIF-IA from exponentially growing cells and have shown that it is a polypeptide with a molecular mass of 75 kDa which exists as a monomer in solution. Using a reconstituted transcription system consisting of purified transcription factors, we demonstrate that TIF-IA is a bona fide transcription initiation factor which interacts with RNA polymerase I. Preinitiation complexes can be assembled in the absence of TIF-IA, but formation of the first phosphodiester bonds of nascent rRNA is precluded. After initiation, TIF-IA is liberated from the initiation complex and facilitates transcription from templates bearing preinitiation complexes which lack TIF-IA. Despite the pronounced species specificity of class I gene transcription, this growth-dependent factor has been identified not only in mouse but also in human cells. Murine TIF-IA complements extracts from both growth-inhibited mouse and human cells. The analogous human activity appears to be similar or identical to that of TIF-IA. Therefore, despite the fact that the RNA polymerase transcription system has evolved sufficiently rapidly that an rDNA promoter from one species will not function in another species, the basic mechanisms that adapt ribosome synthesis to cell proliferation have been conserved.

  13. Insulin-like Growth Factor (IGF) Signaling Requires αvβ3-IGF1-IGF Type 1 Receptor (IGF1R) Ternary Complex Formation in Anchorage Independence, and the Complex Formation Does Not Require IGF1R and Src Activation

    PubMed Central

    Fujita, Masaaki; Takada, Yoko K.; Takada, Yoshikazu

    2013-01-01

    Integrin αvβ3 plays a role in insulin-like growth factor 1 (IGF1) signaling (integrin-IGF1 receptor (IGF1R) cross-talk) in non-transformed cells in anchorage-dependent conditions. We reported previously that IGF1 directly binds to αvβ3 and induces αvβ3-IGF1-IGF1R ternary complex formation in these conditions. The integrin-binding defective IGF1 mutant (R36E/R37E) is defective in inducing ternary complex formation and IGF signaling, whereas it still binds to IGF1R. We studied if IGF1 can induce signaling in anchorage-independent conditions in transformed Chinese hamster ovary cells that express αvβ3 (β3-CHO) cells. Here we describe that IGF1 signals were more clearly detectable in anchorage-independent conditions (polyHEMA-coated plates) than in anchorage-dependent conditions. This suggests that IGF signaling is masked by signals from cell-matrix interaction in anchorage-dependent conditions. IGF signaling required αvβ3 expression, and R36E/R37E was defective in inducing signals in polyHEMA-coated plates. These results suggest that αvβ3-IGF1 interaction, not αvβ3-extracellular matrix interaction, is essential for IGF signaling. Inhibitors of IGF1R, Src, AKT, and ERK1/2 did not suppress αvβ3-IGF-IGF1R ternary complex formation, suggesting that activation of these kinases are not required for ternary complex formation. Also, mutations of the β3 cytoplasmic tail (Y747F and Y759F) that block β3 tyrosine phosphorylation did not affect IGF1R phosphorylation or AKT activation. We propose a model in which IGF1 binding to IGF1R induces recruitment of integrin αvβ3 to the IGF-IGF1R complex and then β3 and IGF1R are phosphorylated. It is likely that αvβ3 should be together with the IGF1-IGF1R complex for triggering IGF signaling. PMID:23243309

  14. Comparing anterior and posterior Hox complex formation reveals guidelines for predicting cis-regulatory elements

    PubMed Central

    Uhl, Juli D.; Cook, Tiffany A.; Gebelein, Brian

    2010-01-01

    Hox transcription factors specify numerous cell fates along the anterior-posterior axis by regulating the expression of downstream target genes. While expression analysis has uncovered large numbers of de-regulated genes in cells with altered Hox activity, determining which are direct versus indirect targets has remained a significant challenge. Here, we characterize the DNA binding activity of Hox transcription factor complexes on eight experimentally verified cis-regulatory elements. Hox factors regulate the activity of each element by forming protein complexes with two cofactor proteins, Extradenticle (Exd) and Homothorax (Hth). Using comparative DNA binding assays, we found that a number of flexible arrangements of Hox, Exd, and Hth binding sites mediate cooperative transcription factor complexes. Moreover, analysis of a Distal-less regulatory element (DMXR) that is repressed by abdominal Hox factors revealed that suboptimal binding sites can be combined to form high affinity transcription complexes. Lastly, we determined that the anterior Hox factors are more dependent upon Exd and Hth for complex formation than posterior Hox factors. Based upon these findings, we suggest a general set of guidelines to serve as a basis for designing bioinformatics algorithms aimed at identifying Hox regulatory elements using the wealth of recently sequenced genomes. PMID:20398649

  15. Deficiency of PHB complex impairs respiratory supercomplex formation and activates mitochondrial flashes.

    PubMed

    Jian, Chongshu; Xu, Fengli; Hou, Tingting; Sun, Tao; Li, Jinghang; Cheng, Heping; Wang, Xianhua

    2017-08-01

    Prohibitins (PHBs; prohibitin 1, PHB1 or PHB, and prohibitin 2, PHB2) are evolutionarily conserved and ubiquitously expressed mitochondrial proteins. PHBs form multimeric ring complexes acting as scaffolds in the inner mitochondrial membrane. Mitochondrial flashes (mitoflashes) are newly discovered mitochondrial signaling events that reflect electrical and chemical excitations of the organelle. Here, we investigate the possible roles of PHBs in the regulation of mitoflash signaling. Downregulation of PHBs increases mitoflash frequency by up to 5.4-fold due to elevated basal reactive oxygen species (ROS) production in the mitochondria. Mechanistically, PHB deficiency impairs the formation of mitochondrial respiratory supercomplexes (RSCs) without altering the abundance of individual respiratory complex subunits. These impairments induced by PHB deficiency are effectively rescued by co-expression of PHB1 and PHB2, indicating that the multimeric PHB complex acts as the functional unit. Furthermore, downregulating other RSC assembly factors, including SCAFI (also known as COX7A2L), RCF1a (HIGD1A), RCF1b (HIGD2A), UQCC3 and SLP2 (STOML2), all activate mitoflashes through elevating mitochondrial ROS production. Our findings identify the PHB complex as a new regulator of RSC formation and mitoflash signaling, and delineate a general relationship among RSC formation, basal ROS production and mitoflash biogenesis. © 2017. Published by The Company of Biologists Ltd.

  16. Molecular cloning and expression of a gene for a factor which stabilizes formation of inhibitor-mitochondrial ATPase complex from Saccharomyces cerevisiae.

    PubMed

    Akashi, A; Yoshida, Y; Nakagoshi, H; Kuroki, K; Hashimoto, T; Tagawa, K; Imamoto, F

    1988-10-01

    Stabilizing factor, a 9 kDa protein, stabilizes and facilitates formation of the complex between mitochondrial ATP synthase and its intrinsic inhibitor protein. A clone containing the gene encoding the 9 kDa protein was selected from a yeast genomic library to determine the structure of its precursor protein. As deduced from the nucleotide sequence, the precursor of the yeast 9 kDa stabilizing factor contains 86 amino acid residues and has a molecular weight of 10,062. From the predicted sequence we infer that the stabilizing factor precursor contains a presequence of 23 amino acid residues at its amino terminus. We also used S1 mapping to determine the initiation site of transcription under glucose-repressed or derepressed conditions. These experiments suggest that transcription of this gene starts at three different sites and that only one of them is not affected by the presence of glucose.

  17. Bacillus subtilis δ Factor Functions as a Transcriptional Regulator by Facilitating the Open Complex Formation.

    PubMed

    Prajapati, Ranjit Kumar; Sengupta, Shreya; Rudra, Paulami; Mukhopadhyay, Jayanta

    2016-01-15

    Most bacterial RNA polymerases (RNAP) contain five conserved subunits, viz. 2α, β, β', and ω. However, in many Gram-positive bacteria, especially in fermicutes, RNAP is associated with an additional factor, called δ. For over three decades since its identification, it had been thought that δ functioned as a subunit of RNAP to enhance the level of transcripts by recycling RNAP. In support of the previous observations, we also find that δ is involved in recycling of RNAP by releasing the RNA from the ternary complex. We further show that δ binds to RNA and is able to recycle RNAP when the length of the nascent RNA reaches a critical length. However, in this work we decipher a new function of δ. Performing biochemical and mutational analysis, we show that Bacillus subtilis δ binds to DNA immediately upstream of the promoter element at A-rich sequences on the abrB and rrnB1 promoters and facilitates open complex formation. As a result, δ facilitates RNAP to initiate transcription in the second scale, compared with minute scale in the absence of δ. Using transcription assay, we show that δ-mediated recycling of RNAP cannot be the sole reason for the enhancement of transcript yield. Our observation that δ does not bind to RNAP holo enzyme but is required to bind to DNA upstream of the -35 promoter element for transcription activation suggests that δ functions as a transcriptional regulator. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. The interaction of E. coli integration host factor and lambda cos DNA: multiple complex formation and protein-induced bending.

    PubMed Central

    Kosturko, L D; Daub, E; Murialdo, H

    1989-01-01

    The interaction of E. coli's integration Host Factor (IHF) with fragments of lambda DNA containing the cos site has been studied by gel-mobility retardation and electron microscopy. The cos fragment used in the mobility assays is 398 bp and spans a region from 48,298 to 194 on the lambda chromosome. Several different complexes of IHF with this fragment can be distinguished by their differential mobility on polyacrylamide gels. Relative band intensities indicate that the formation of a complex between IHF and this DNA fragment has an equilibrium binding constant of the same magnitude as DNA fragments containing lambda's attP site. Gel-mobility retardation and electron microscopy have been employed to show that IHF sharply bends DNA near cos and to map the bending site. The protein-induced bend is near an intrinsic bend due to DNA sequence. The position of the bend suggests that IHF's role in lambda DNA packaging may be the enhancement of terminase binding/cos cutting by manipulating DNA structure. Images PMID:2521383

  19. Positronium formation studies in solid molecular complexes: Triphenylphosphine oxide-triphenylmethanol

    NASA Astrophysics Data System (ADS)

    Oliveira, F. C.; Denadai, A. M. L.; Fulgêncio, F. H.; Magalhães, W. F.; Alcântara, A. F. C.; Windmöller, D.; Machado, J. C.

    2012-06-01

    Positronium formation in triphenylphosphine oxide (TPPO), triphenylmethanol (TPM), and systems [TPPO(1-X)ṡTPMX] has been studied. The low probability of positronium formation in complex [TPPO0.5ṡTPM0.5] was attributed to strong hydrogen bond and sixfold phenyl embrace interactions. These strong interactions in complex reduce the possibility of the n- and π-electrons to interact with positrons on the spur and consequently, the probability of positronium formation is lower. The τ3 parameter and free volume (correlated to τ3) were also sensitive to the formation of hydrogen bonds and sixfold phenyl embrace interactions within the complex. For physical mixture the positron annihilation parameters remained unchanged throughout the composition range.

  20. CAPS drives trans-SNARE complex formation and membrane fusion through syntaxin interactions.

    PubMed

    James, Declan J; Kowalchyk, Judith; Daily, Neil; Petrie, Matt; Martin, Thomas F J

    2009-10-13

    Ca(2+)-dependent activator protein for secretion (CAPS) is an essential factor for regulated vesicle exocytosis that functions in priming reactions before Ca(2+)-triggered fusion of vesicles with the plasma membrane. However, the precise events that CAPS regulates to promote vesicle fusion are unclear. In the current work, we reconstituted CAPS function in a SNARE-dependent liposome fusion assay using VAMP2-containing donor and syntaxin-1/SNAP-25-containing acceptor liposomes. The CAPS stimulation of fusion required PI(4,5)P(2) in acceptor liposomes and was independent of Ca(2+), but Ca(2+) dependence was restored by inclusion of synaptotagmin. CAPS stimulated trans-SNARE complex formation concomitant with the stimulation of full membrane fusion at physiological SNARE densities. CAPS bound syntaxin-1, and CAPS truncations that competitively inhibited syntaxin-1 binding also inhibited CAPS-dependent fusion. The results revealed an unexpected activity of a priming protein to accelerate fusion by efficiently promoting trans-SNARE complex formation. CAPS may function in priming by organizing SNARE complexes on the plasma membrane.

  1. Involvement of DPP-IV catalytic residues in enzyme–saxagliptin complex formation

    PubMed Central

    Metzler, William J.; Yanchunas, Joseph; Weigelt, Carolyn; Kish, Kevin; Klei, Herbert E.; Xie, Dianlin; Zhang, Yaqun; Corbett, Martin; Tamura, James K.; He, Bin; Hamann, Lawrence G.; Kirby, Mark S.; Marcinkeviciene, Jovita

    2008-01-01

    The inhibition of DPP-IV by saxagliptin has been proposed to occur through formation of a covalent but reversible complex. To evaluate further the mechanism of inhibition, we determined the X-ray crystal structure of the DPP-IV:saxagliptin complex. This structure reveals covalent attachment between S630 and the inhibitor nitrile carbon (C–O distance <1.3 Å). To investigate whether this serine addition is assisted by the catalytic His-Asp dyad, we generated two mutants of DPP-IV, S630A and H740Q, and assayed them for ability to bind inhibitor. DPP-IVH740Q bound saxagliptin with an ∼1000-fold reduction in affinity relative to DPP-IVWT, while DPP-IVS630A showed no evidence for binding inhibitor. An analog of saxagliptin lacking the nitrile group showed unchanged binding properties to the both mutant proteins, highlighting the essential role S630 and H740 play in covalent bond formation between S630 and saxagliptin. Further supporting mechanism-based inhibition by saxagliptin, NMR spectra of enzyme–saxagliptin complexes revealed the presence of three downfield resonances with low fractionation factors characteristic of short and strong hydrogen bonds (SSHB). Comparison of the NMR spectra of various wild-type and mutant DPP-IV:ligand complexes enabled assignment of a resonance at ∼14 ppm to H740. Two additional DPP-IV mutants, Y547F and Y547Q, generated to probe potential stabilization of the enzyme–inhibitor complex by this residue, did not show any differences in inhibitor binding either by ITC or NMR. Together with the previously published enzymatic data, the structural and binding data presented here strongly support a histidine-assisted covalent bond formation between S630 hydroxyl oxygen and the nitrile group of saxagliptin. PMID:18227430

  2. Involvement of DPP-IV Catalytic Residues in Enzyme-Saxagliptin Complex Formation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Metzler,W.; Yanchunas, J.; Weigelt, C.

    The inhibition of DPP-IV by saxagliptin has been proposed to occur through formation of a covalent but reversible complex. To evaluate further the mechanism of inhibition, we determined the X-ray crystal structure of the DPP-IV:saxagliptin complex. This structure reveals covalent attachment between S630 and the inhibitor nitrile carbon (C-O distance <1.3 Angstroms). To investigate whether this serine addition is assisted by the catalytic His-Asp dyad, we generated two mutants of DPP-IV, S630A and H740Q, and assayed them for ability to bind inhibitor. DPP-IVH740Q bound saxagliptin with an {approx}1000-fold reduction in affinity relative to DPP-IVWT, while DPP-IVS630A showed no evidence formore » binding inhibitor. An analog of saxagliptin lacking the nitrile group showed unchanged binding properties to the both mutant proteins, highlighting the essential role S630 and H740 play in covalent bond formation between S630 and saxagliptin. Further supporting mechanism-based inhibition by saxagliptin, NMR spectra of enzyme-saxagliptin complexes revealed the presence of three downfield resonances with low fractionation factors characteristic of short and strong hydrogen bonds (SSHB). Comparison of the NMR spectra of various wild-type and mutant DPP-IV:ligand complexes enabled assignment of a resonance at {approx}14 ppm to H740. Two additional DPP-IV mutants, Y547F and Y547Q, generated to probe potential stabilization of the enzyme-inhibitor complex by this residue, did not show any differences in inhibitor binding either by ITC or NMR. Together with the previously published enzymatic data, the structural and binding data presented here strongly support a histidine-assisted covalent bond formation between S630 hydroxyl oxygen and the nitrile group of saxagliptin.« less

  3. Curcumin complexation with cyclodextrins by the autoclave process: Method development and characterization of complex formation.

    PubMed

    Hagbani, Turki Al; Nazzal, Sami

    2017-03-30

    One approach to enhance curcumin (CUR) aqueous solubility is to use cyclodextrins (CDs) to form inclusion complexes where CUR is encapsulated as a guest molecule within the internal cavity of the water-soluble CD. Several methods have been reported for the complexation of CUR with CDs. Limited information, however, is available on the use of the autoclave process (AU) in complex formation. The aims of this work were therefore to (1) investigate and evaluate the AU cycle as a complex formation method to enhance CUR solubility; (2) compare the efficacy of the AU process with the freeze-drying (FD) and evaporation (EV) processes in complex formation; and (3) confirm CUR stability by characterizing CUR:CD complexes by NMR, Raman spectroscopy, DSC, and XRD. Significant differences were found in the saturation solubility of CUR from its complexes with CD when prepared by the three complexation methods. The AU yielded a complex with expected chemical and physical fingerprints for a CUR:CD inclusion complex that maintained the chemical integrity and stability of CUR and provided the highest solubility of CUR in water. Physical and chemical characterizations of the AU complexes confirmed the encapsulated of CUR inside the CD cavity and the transformation of the crystalline CUR:CD inclusion complex to an amorphous form. It was concluded that the autoclave process with its short processing time could be used as an alternate and efficient methods for drug:CD complexation. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Environmental factors that shape biofilm formation.

    PubMed

    Toyofuku, Masanori; Inaba, Tomohiro; Kiyokawa, Tatsunori; Obana, Nozomu; Yawata, Yutaka; Nomura, Nobuhiko

    2016-01-01

    Cells respond to the environment and alter gene expression. Recent studies have revealed the social aspects of bacterial life, such as biofilm formation. Biofilm formation is largely affected by the environment, and the mechanisms by which the gene expression of individual cells affects biofilm development have attracted interest. Environmental factors determine the cell's decision to form or leave a biofilm. In addition, the biofilm structure largely depends on the environment, implying that biofilms are shaped to adapt to local conditions. Second messengers such as cAMP and c-di-GMP are key factors that link environmental factors with gene regulation. Cell-to-cell communication is also an important factor in shaping the biofilm. In this short review, we will introduce the basics of biofilm formation and further discuss environmental factors that shape biofilm formation. Finally, the state-of-the-art tools that allow us investigate biofilms under various conditions are discussed.

  5. Porcine endothelium induces DNA-histone complex formation in human whole blood: a harmful effect of histone on coagulation and endothelial activation.

    PubMed

    Yoo, Hyun Ju; Kim, Ji-Eun; Gu, Ja Yoon; Lee, Sae Bom; Lee, Hyun Joo; Hwang, Ho Young; Hwang, Yoohwa; Kim, Young Tae; Kim, Hyun Kyung

    2016-11-01

    Neutrophils play a role in xenograft rejection. When neutrophils are stimulated, they eject the DNA-histone complex into the extracellular space, called neutrophil extracellular traps (NET). We investigated whether NET formation actively occurs in the xenograft and contributes to coagulation and endothelial activation. Human whole blood was incubated with porcine aortic endothelial cells (pEC) from wild-type or α1,3-galactosyltransferase gene-knockout (GTKO) pigs. In the supernatant plasma from human blood, the level of the DNA-histone complex was measured by ELISA, and thrombin generation was measured using a calibrated automated thrombogram. Histone-induced tissue factor and adhesion molecule expression were measured by flow cytometry. pEC from both wild-type and GTKO pigs significantly induced DNA-histone complex formation in human whole blood. The DNA-histone complex produced shortened the thrombin generation time and clotting time. Histone alone dose-dependently induced tissue factor and adhesion molecule expression in pEC. Aurintricarboxylic acid pretreatment partially inhibited pEC-induced DNA-histone complex formation. DNA-histone complex actively generated upon xenotransplantation is a novel target to inhibit coagulation and endothelial activation. To prevent tissue factor and adhesion molecule expression, a strategy to block soluble histone may be required in xenotransplantation. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. Formation, Migration, and Reactivity of Au CO Complexes on Gold Surfaces

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Jun; McEntee, Monica; Tang, Wenjie

    2016-01-12

    Here, we report experimental as well as theoretical evidence that suggests Au CO complex formation upon the exposure of CO to active sites (step edges and threading dislocations) on a Au(111) surface. Room-temperature scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy, transmission infrared spectroscopy, and density functional theory calculations point to Au CO complex formation and migration. Room-temperature STM of the Au(111) surface at CO pressures in the range from 10^ 8 to 10^ 4 Torr (dosage up to 10^6 langmuir) indicates Au atom extraction from dislocation sites of the herringbone reconstruction, mobile Au CO complex formation and diffusion, and Aumore » adatom cluster formation on both elbows and step edges on the Au surface. The formation and mobility of the Au CO complex result from the reduced Au Au bonding at elbows and step edges leading to stronger Au CO bonding and to the formation of a more positively charged CO (CO +) on Au. These studies indicate that the mobile Au CO complex is involved in the Au nanoparticle formation and reactivity, and that the positive charge on CO increases due to the stronger adsorption of CO at Au sites with lower coordination numbers.« less

  7. Geology of the Biwabik Iron Formation and Duluth Complex.

    PubMed

    Jirsa, Mark A; Miller, James D; Morey, G B

    2008-10-01

    The Biwabik Iron Formation is a approximately 1.9 billion year-old sequence of iron-rich sedimentary rocks that was metamorphosed at its eastern-most extent by approximately 1.1 billion year-old intrusions of the Duluth Complex. The metamorphic recrystallization of iron-formation locally produced iron-rich amphiboles and other fibrous iron-silicate minerals. The presence of these minerals in iron-formation along the eastern part of what is known as the Mesabi Iron Range, and their potential liberation by iron mining has raised environmental health concerns. We describe here the geologic setting and mineralogic composition of the Biwabik Iron Formation in and adjacent to the contact metamorphic aureole of the Duluth Complex. The effects of metamorphism are most pronounced within a few kilometers of the contact, and decrease progressively away from it. The contact aureole has been divided into four metamorphic zones-each characterized by the composition and crystal structure of the metamorphic minerals it contains. The recrystallization of iron-formation to iron-rich amphibole minerals (grunerite and cummingtonite) and iron-pyroxene minerals (hedenbergite and ferrohypersthene) is best developed in zones that are most proximal to the Duluth Complex contact.

  8. Geology of the Biwabik Iron Formation and Duluth Complex

    USGS Publications Warehouse

    Jirsa, M.A.; Miller, J.D.; Morey, G.B.

    2008-01-01

    The Biwabik Iron Formation is a ???1.9 billion year-old sequence of iron-rich sedimentary rocks that was metamorphosed at its eastern-most extent by ???1.1 billion year-old intrusions of the Duluth Complex. The metamorphic recrystallization of iron-formation locally produced iron-rich amphiboles and other fibrous iron-silicate minerals. The presence of these minerals in iron-formation along the eastern part of what is known as the Mesabi Iron Range, and their potential liberation by iron mining has raised environmental health concerns. We describe here the geologic setting and mineralogic composition of the Biwabik Iron Formation in and adjacent to the contact metamorphic aureole of the Duluth Complex. The effects of metamorphism are most pronounced within a few kilometers of the contact, and decrease progressively away from it. The contact aureole has been divided into four metamorphic zones-each characterized by the composition and crystal structure of the metamorphic minerals it contains. The recrystallization of iron-formation to iron-rich amphibole minerals (grunerite and cummingtonite) and iron-pyroxene minerals (hedenbergite and ferrohypersthene) is best developed in zones that are most proximal to the Duluth Complex contact. ?? 2007 Elsevier Inc. All rights reserved.

  9. Zein/caseinate/pectin complex nanoparticles: Formation and characterization.

    PubMed

    Chang, Chao; Wang, Taoran; Hu, Qiaobin; Luo, Yangchao

    2017-11-01

    In this study, pectin was used as coating material to form zein/caseinate/pectin complex nanoparticles through pH adjustment and heating treatment for potential oral delivery applications. The preparation conditions were studied by applying heating treatment at different pHs, either the isoelectric point of zein (pH 6.2) or caseinate (pH 4.6), or consecutively at both pHs. The particulate characteristics, including particle size, polydispersity index, and zeta potential were monitored for complex nanoparticles formed under different preparation conditions. The complex nanoparticles generally exhibited particle size smaller than 200nm with narrow distribution, spherical shape, and strong negative charge. Fourier transform infrared and fluorescence spectroscopy revealed that hydrophobic interactions and hydrogen bonds were involved in the formation of complex nanoparticles, in addition to electrostatic interactions. Fresh colloidal dispersion and freeze-dried powders varied in their morphology, depending on their preparation conditions. Our results suggested that heating pH and sequence significantly affected the morphology of complex nanoparticles, and pectin coating exerted stabilization effect under simulated gastrointestinal conditions. The present study provides insight into the formation of protein/polysaccharide complex nanoparticles under different preparation conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Direct evidence of an elongation factor-Tu/Ts·GTP·Aminoacyl-tRNA quaternary complex.

    PubMed

    Burnett, Benjamin J; Altman, Roger B; Ferguson, Angelica; Wasserman, Michael R; Zhou, Zhou; Blanchard, Scott C

    2014-08-22

    During protein synthesis, elongation factor-Tu (EF-Tu) bound to GTP chaperones the entry of aminoacyl-tRNA (aa-tRNA) into actively translating ribosomes. In so doing, EF-Tu increases the rate and fidelity of the translation mechanism. Recent evidence suggests that EF-Ts, the guanosine nucleotide exchange factor for EF-Tu, directly accelerates both the formation and dissociation of the EF-Tu-GTP-Phe-tRNA(Phe) ternary complex (Burnett, B. J., Altman, R. B., Ferrao, R., Alejo, J. L., Kaur, N., Kanji, J., and Blanchard, S. C. (2013) J. Biol. Chem. 288, 13917-13928). A central feature of this model is the existence of a quaternary complex of EF-Tu/Ts·GTP·aa-tRNA(aa). Here, through comparative investigations of phenylalanyl, methionyl, and arginyl ternary complexes, and the development of a strategy to monitor their formation and decay using fluorescence resonance energy transfer, we reveal the generality of this newly described EF-Ts function and the first direct evidence of the transient quaternary complex species. These findings suggest that EF-Ts may regulate ternary complex abundance in the cell through mechanisms that are distinct from its guanosine nucleotide exchange factor functions. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. The Dynamics of Coalition Formation on Complex Networks

    NASA Astrophysics Data System (ADS)

    Auer, S.; Heitzig, J.; Kornek, U.; Schöll, E.; Kurths, J.

    2015-08-01

    Complex networks describe the structure of many socio-economic systems. However, in studies of decision-making processes the evolution of the underlying social relations are disregarded. In this report, we aim to understand the formation of self-organizing domains of cooperation (“coalitions”) on an acquaintance network. We include both the network’s influence on the formation of coalitions and vice versa how the network adapts to the current coalition structure, thus forming a social feedback loop. We increase complexity from simple opinion adaptation processes studied in earlier research to more complex decision-making determined by costs and benefits, and from bilateral to multilateral cooperation. We show how phase transitions emerge from such coevolutionary dynamics, which can be interpreted as processes of great transformations. If the network adaptation rate is high, the social dynamics prevent the formation of a grand coalition and therefore full cooperation. We find some empirical support for our main results: Our model develops a bimodal coalition size distribution over time similar to those found in social structures. Our detection and distinguishing of phase transitions may be exemplary for other models of socio-economic systems with low agent numbers and therefore strong finite-size effects.

  12. Formation of the acrosome complex in the bush cricket Gampsocleis gratiosa (Orthoptera: Tettigoniidae).

    PubMed

    Su, Cai Xia; Chen, Jie; Shi, Fu Ming; Guo, Ming Shen; Chang, Yan Lin

    2017-07-01

    The acrosome complex plays an indispensable role in the normal function of mature spermatozoa. However, the dynamic process of acrosome complex formation in insect remains poorly understood. Gampsocleis gratiosa Brunner von Wattenwyl possesses the typical characteristic of insect sperms, which is tractable in terms of size, and therefore was selected for the acrosome formation study in this report. The results show that acrosome formation can be divided into six phases: round, rotating, rhombic, cylindrical, transforming and mature phase, based on the morphological dynamics of acrosome complex and nucleus. In addition, the cytoskeleton plays a critical role in the process of acrosome formation. The results from this study indicate that: (1) glycoprotein is the major component of the acrosome proper; (2) the microfilament is one element of the acrosome complex, and may mediate the morphologic change of the acrosome complex; (3) the microtubules might also shape the nucleus and acrosome complex during the acrosome formation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Experimental Investigation of the Formation of Complex Craters

    NASA Astrophysics Data System (ADS)

    Martellato, E.; Dörfler, M. A.; Schuster, B.; Wünnemman, K.; Kenkmann, T.

    2017-09-01

    The formation of complex impact craters is still poorly understood, because standard material models fail to explain the gravity-driven collapse at the observed size-range of a bowl-shaped transient crater into a flat-floored crater structure with a central peak or ring and terraced rim. To explain such a collapse the so-called Acoustic Fluidization (AF) model has been proposed. The AF assumes that heavily fractured target rocks surrounding the transient crater are temporarily softened by an acoustic field in the wake of an expanding shock wave generated upon impact. The AF has been successfully employed in numerous modeling studies of complex crater formation; however, there is no clear relationship between model parameters and observables. In this study, we present preliminary results of laboratory experiments aiming at relating the AF parameters to observables such as the grain size, average wave length of the acoustic field and its decay time τ relative to the crater formation time.

  14. Comparative analysis of the ternary complex factors Elk-1, SAP-1a and SAP-2 (ERP/NET).

    PubMed Central

    Price, M A; Rogers, A E; Treisman, R

    1995-01-01

    A transcription factor ternary complex composed of Serum Response Factor (SRF) and Ternary Complex Factor (TCF) mediates the response of the c-fos Serum Response Element (SRE) to growth factors and mitogens. Three Ets domain proteins, Elk-1, SAP-1 and ERP/NET, have been reported to have the properties of TCF. Here we compare Elk-1 and SAP-1a with the human ERP/NET homologue SAP-2. All three TCF RNAs are ubiquitously expressed at similar relative levels. All three proteins contain conserved regions that interact with SRF and the c-fos SRE with comparable efficiency, but in vitro complex formation by SAP-2 is strongly inhibited by its C-terminal sequences. Similarly, only Elk-1 and SAP-1a efficiently bind the c-fos SRE in vivo; ternary complex formation by SAP-2 is weak and is substantially unaffected by serum stimulation or v-ras co-expression. All three TCFs contain C-terminal transcriptional activation domains that are phosphorylated following growth factor stimulation. Activation requires conserved S/T-P motifs found in all the TCF family members. Each TCF activation domain can be phosphorylated in vitro by partially purified ERK2, and ERK activation in vivo is sufficient to potentiate transcriptional activation. Images PMID:7540136

  15. Comparative analysis of the ternary complex factors Elk-1, SAP-1a and SAP-2 (ERP/NET).

    PubMed

    Price, M A; Rogers, A E; Treisman, R

    1995-06-01

    A transcription factor ternary complex composed of Serum Response Factor (SRF) and Ternary Complex Factor (TCF) mediates the response of the c-fos Serum Response Element (SRE) to growth factors and mitogens. Three Ets domain proteins, Elk-1, SAP-1 and ERP/NET, have been reported to have the properties of TCF. Here we compare Elk-1 and SAP-1a with the human ERP/NET homologue SAP-2. All three TCF RNAs are ubiquitously expressed at similar relative levels. All three proteins contain conserved regions that interact with SRF and the c-fos SRE with comparable efficiency, but in vitro complex formation by SAP-2 is strongly inhibited by its C-terminal sequences. Similarly, only Elk-1 and SAP-1a efficiently bind the c-fos SRE in vivo; ternary complex formation by SAP-2 is weak and is substantially unaffected by serum stimulation or v-ras co-expression. All three TCFs contain C-terminal transcriptional activation domains that are phosphorylated following growth factor stimulation. Activation requires conserved S/T-P motifs found in all the TCF family members. Each TCF activation domain can be phosphorylated in vitro by partially purified ERK2, and ERK activation in vivo is sufficient to potentiate transcriptional activation.

  16. Formation of complex bacterial colonies via self-generated vortices

    NASA Astrophysics Data System (ADS)

    Czirók, András; Ben-Jacob, Eshel; Cohen, Inon; Vicsek, Tamás

    1996-08-01

    Depending on the environmental conditions bacterial colonies growing on agar surfaces can exhibit complex colony formation and various types of collective motion. Experimental results are presented concerning the hydrodynamics (vortices, migration of bacteria in clusters) and colony formation of a morphotype of Bacillus subtilis. Some of these features are not specific to this morphotype but also have been observed in several other bacterial strains, suggesting the presence of universal effects. A simple model of self-propelled particles is proposed, which is capable of describing the hydrodynamics on the intermediate level, including the experimentally observed rotating disks of bacteria. The colony formation is captured by a complex generic model taking into account nutrient diffusion, reproduction, and sporulation of bacteria, extracellular slime deposition, chemoregulation, and inhomogeneous population. Our model also sheds light on some possible biological benefits of this ``multicellular behavior.''

  17. Inhibition of amyloid peptide fibril formation by gold-sulfur complexes.

    PubMed

    Wang, Wenji; Zhao, Cong; Zhu, Dengsen; Gong, Gehui; Du, Weihong

    2017-06-01

    Amyloid-related diseases are characterized by protein conformational change and amyloid fibril deposition. Metal complexes are potential inhibitors of amyloidosis. Nitrogen-coordinated gold complexes have been used to disaggregate prion neuropeptide (PrP106-126) and human islet amyloid polypeptide (hIAPP). However, the roles of metal complexes in peptide fibril formation and related bioactivity require further exploration. In this work, we investigated the interactions of amyloid peptides PrP106-126 and hIAPP with two tetracoordinated gold-sulfur complexes, namely, dichloro diethyl dithiocarbamate gold complex and dichloro pyrrolidine dithiocarbamate gold complex. We also determined the effects of these complexes on peptide-induced cytotoxicity. Thioflavin T assay, morphological characterization, and particle size analysis indicated that the two gold-sulfur complexes effectively inhibited the fibrillation of the amyloid peptides, which led to the formation of nanoscale particles. The complexes reduced the cytotoxicity induced by the amyloid peptides. Intrinsic fluorescence, nuclear magnetic resonance, and mass spectrometry revealed that the complexes interacted with PrP106-126 and hIAPP via metal coordination and hydrophobic interaction, which improved the inhibition and binding of the two gold-sulfur compounds. Our study provided new insights into the use of tetracoordinated gold-sulfur complexes as drug candidates against protein conformational disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. The History and Rate of Star Formation within the G305 Complex

    NASA Astrophysics Data System (ADS)

    Faimali, Alessandro Daniele

    2013-07-01

    Within this thesis, we present an extended multiwavelength analysis of the rich massive Galactic star-forming complex G305. We have focused our attention on studying the both the embedded massive star-forming population within G305, while also identifying the intermediate-, to lowmass content of the region also. Though massive stars play an important role in the shaping and evolution of their host galaxies, the physics of their formation still remains unclear. We have therefore set out to studying the nature of star formation within this complex, and also identify the impact that such a population has on the evolution of G305. We firstly present a Herschel far-infrared study towards G305, utilising PACS 70, 160 micron and SPIRE 250, 350, and 500 micron observations from the Hi-GAL survey of the Galactic plane. The focus of this study is to identify the embedded massive star-forming population within G305, by combining far-infrared data with radio continuum, H2O maser, methanol maser, MIPS, and Red MSX Source survey data available from previous studies. From this sample we identify some 16 candidate associations are identified as embedded massive star-forming regions, and derive a two-selection colour criterion from this sample of log(F70/F500) >= 1 and log(F160/F350) >= 1.6 to identify an additional 31 embedded massive star candidates with no associated star-formation tracers. Using this result, we are able to derive a star formation rate (SFR) of 0.01 - 0.02 Msun/yr. Comparing this resolved star formation rate, to extragalactic star formation rate tracers (based on the Kennicutt-Schmidt relation), we find the star formation activity is underestimated by a factor of >=2 in comparison to the SFR derived from the YSO population. By next combining data available from 2MASS and VVV, Spitzer GLIMPSE and MIPSGAL, MSX, and Herschel Hi-GAL, we are able to identify the low-, to intermediate-mass YSOs present within the complex. Employing a series of stringent colour

  19. Single-stranded nucleic acids promote SAMHD1 complex formation.

    PubMed

    Tüngler, Victoria; Staroske, Wolfgang; Kind, Barbara; Dobrick, Manuela; Kretschmer, Stefanie; Schmidt, Franziska; Krug, Claudia; Lorenz, Mike; Chara, Osvaldo; Schwille, Petra; Lee-Kirsch, Min Ae

    2013-06-01

    SAM domain and HD domain-containing protein 1 (SAMHD1) is a dGTP-dependent triphosphohydrolase that degrades deoxyribonucleoside triphosphates (dNTPs) thereby limiting the intracellular dNTP pool. Mutations in SAMHD1 cause Aicardi-Goutières syndrome (AGS), an inflammatory encephalopathy that mimics congenital viral infection and that phenotypically overlaps with the autoimmune disease systemic lupus erythematosus. Both disorders are characterized by activation of the antiviral cytokine interferon-α initiated by immune recognition of self nucleic acids. Here we provide first direct evidence that SAMHD1 associates with endogenous nucleic acids in situ. Using fluorescence cross-correlation spectroscopy, we demonstrate that SAMHD1 specifically interacts with ssRNA and ssDNA and establish that nucleic acid-binding and formation of SAMHD1 complexes are mutually dependent. Interaction with nucleic acids and complex formation do not require the SAM domain, but are dependent on the HD domain and the C-terminal region of SAMHD1. We finally demonstrate that mutations associated with AGS exhibit both impaired nucleic acid-binding and complex formation implicating that interaction with nucleic acids is an integral aspect of SAMHD1 function.

  20. Positronium formation studies in crystalline molecular complexes: Triphenylphosphine oxide - Acetanilide

    NASA Astrophysics Data System (ADS)

    Oliveira, F. C.; Denadai, A. M. L.; Guerra, L. D. L.; Fulgêncio, F. H.; Windmöller, D.; Santos, G. C.; Fernandes, N. G.; Yoshida, M. I.; Donnici, C. L.; Magalhães, W. F.; Machado, J. C.

    2013-04-01

    Hydrogen bond formation in the triphenylphosphine oxide (TPPO), acetanilide (ACN) supramolecular heterosynton system, named [TPPO0.5·ACN0.5], has been studied by Positron Annihilation Lifetime Spectroscopy (PALS) and supported by several analytical techniques. In toluene solution, Isothermal Titration Calorimetry (ITC) presented a 1:1 stoichiometry and indicated that the complexation process is driven by entropy, with low enthalpy contribution. X-ray structure determination showed the existence of a three-dimensional network of hydrogen bonds, allowing also the confirmation of the existence of a 1:1 crystalline molecular complex in solid state. The results of thermal analysis (TGA, DTA and DSC) and FTIR spectroscopy showed that the interactions in the complex are relatively weaker than those found in pure precursors, leading to a higher positronium formation probability at [TPPO0.5·ACN0.5]. These weak interactions in the complex enhance the possibility of the n- and π-electrons to interact with positrons and consequently, the probability of positronium formation is higher. Through the present work is shown that PALS is a sensible powerful tool to investigate intermolecular interactions in solid heterosynton supramolecular systems.

  1. A Stimulation Function of Synaptotagmin-1 in Ternary SNARE Complex Formation Dependent on Munc18 and Munc13

    PubMed Central

    Li, Yun; Wang, Shen; Li, Tianzhi; Zhu, Le; Xu, Yuanyuan; Ma, Cong

    2017-01-01

    The Ca2+ sensor synaptotagmin-1 (Syt1) plays an essential function in synaptic exocytosis. Recently, Syt1 has been implicated in synaptic vesicle priming, a maturation step prior to Ca2+-triggered membrane fusion that is believed to involve formation of the ternary SNARE complex and require priming proteins Munc18-1 and Munc13-1. However, the mechanisms of Syt1 in synaptic vesicle priming are still unclear. In this study, we found that Syt1 stimulates the transition from the Munc18-1/syntaxin-1 complex to the ternary SNARE complex catalyzed by Munc13-1. This stimulation can be further enhanced in a membrane-containing environment. Further, we showed that Syt1, together with Munc18-1 and Munc13-1, stimulates trans ternary SNARE complex formation on membranes in a manner resistant to disassembly factors NSF and α-SNAP. Disruption of a proposed Syt1/SNARE binding interface strongly abrogated the stimulation function of Syt1. Our results suggest that binding of Syt1 to an intermediate SNARE assembly with Munc18-1 and Munc13-1 is critical for the stimulation function of Syt1 in ternary SNARE complex formation, and this stimulation may underlie the priming function of Syt1 in synaptic exocytosis. PMID:28860966

  2. cAMP prevents TNF-induced apoptosis through inhibiting DISC complex formation in rat hepatocytes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bhattacharjee, Rajesh; Xiang, Wenpei; Family Planning Research Institute, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China

    2012-06-22

    Highlights: Black-Right-Pointing-Pointer cAMP blocks cell death induced by TNF and actinomycin D in cultured hepatocytes. Black-Right-Pointing-Pointer cAMP blocks NF-{kappa}B activation induced by TNF and actinomycin D. Black-Right-Pointing-Pointer cAMP blocks DISC formation following TNF and actinomycin D exposure. Black-Right-Pointing-Pointer cAMP blocks TNF signaling at a proximal step. -- Abstract: Tumor necrosis factor {alpha} (TNF) is a pleiotropic proinflammatory cytokine that plays a role in immunity and the control of cell proliferation, cell differentiation, and apoptosis. The pleiotropic nature of TNF is due to the formation of different signaling complexes upon the binding of TNF to its receptor, TNF receptor type 1more » (TNFR1). TNF induces apoptosis in various mammalian cells when the cells are co-treated with a transcription inhibitor like actinomycin D (ActD). When TNFR1 is activated, it recruits an adaptor protein, TNF receptor-associated protein with death domain (TRADD), through its cytoplasmic death effector domain (DED). TRADD, in turn, recruits other signaling proteins, including TNF receptor-associated protein 2 (TRAF2) and receptor-associated protein kinase (RIPK) 1, to form a complex. Subsequently, this complex combines with FADD and procaspase-8, converts into a death-inducing signaling complex (DISC) to induce apoptosis. Cyclic AMP (cAMP) is a second messenger that regulates various cellular processes such as cell proliferation, gene expression, and apoptosis. cAMP analogues are reported to act as anti-apoptotic agents in various cell types, including hepatocytes. We found that a cAMP analogue, dibutyryl cAMP (db-cAMP), inhibits TNF + ActD-induced apoptosis in rat hepatocytes. The protein kinase A (PKA) inhibitor KT-5720 reverses this inhibitory effect of cAMP on apoptosis. Cytoprotection by cAMP involves down-regulation of various apoptotic signal regulators like TRADD and FADD and inhibition of caspase-8 and caspase-3 cleavage. We

  3. Dissection and engineering of the Escherichia coli formate hydrogenlyase complex.

    PubMed

    McDowall, Jennifer S; Hjersing, M Charlotte; Palmer, Tracy; Sargent, Frank

    2015-10-07

    The Escherichia coli formate hydrogenlyase (FHL) complex is produced under fermentative conditions and couples formate oxidation to hydrogen production. In this work, the architecture of FHL has been probed by analysing affinity-tagged complexes from various genetic backgrounds. In a successful attempt to stabilize the complex, a strain encoding a fusion between FdhF and HycB has been engineered and characterised. Finally, site-directed mutagenesis of the hycG gene was performed, which is predicted to encode a hydrogenase subunit important for regulating sensitivity to oxygen. This work helps to define the core components of FHL and provides solutions to improving the stability of the enzyme. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  4. Double-stranded DNA translocase activity of transcription factor TFIIH and the mechanism of RNA polymerase II open complex formation.

    PubMed

    Fishburn, James; Tomko, Eric; Galburt, Eric; Hahn, Steven

    2015-03-31

    Formation of the RNA polymerase II (Pol II) open complex (OC) requires DNA unwinding mediated by the transcription factor TFIIH helicase-related subunit XPB/Ssl2. Because XPB/Ssl2 binds DNA downstream from the location of DNA unwinding, it cannot function using a conventional helicase mechanism. Here we show that yeast TFIIH contains an Ssl2-dependent double-stranded DNA translocase activity. Ssl2 tracks along one DNA strand in the 5' → 3' direction, implying it uses the nontemplate promoter strand to reel downstream DNA into the Pol II cleft, creating torsional strain and leading to DNA unwinding. Analysis of the Ssl2 and DNA-dependent ATPase activity of TFIIH suggests that Ssl2 has a processivity of approximately one DNA turn, consistent with the length of DNA unwound during transcription initiation. Our results can explain why maintaining the OC requires continuous ATP hydrolysis and the function of TFIIH in promoter escape. Our results also suggest that XPB/Ssl2 uses this translocase mechanism during DNA repair rather than physically wedging open damaged DNA.

  5. Controlled assembly of artificial protein-protein complexes via DNA duplex formation.

    PubMed

    Płoskoń, Eliza; Wagner, Sara C; Ellington, Andrew D; Jewett, Michael C; O'Reilly, Rachel; Booth, Paula J

    2015-03-18

    DNA-protein conjugates have found a wide range of applications. This study demonstrates the formation of defined, non-native protein-protein complexes via the site specific labeling of two proteins of interest with complementary strands of single-stranded DNA in vitro. This study demonstrates that the affinity of two DNA-protein conjugates for one another may be tuned by the use of variable lengths of DNA allowing reversible control of complex formation.

  6. Identification of a novel mitochondrial complex I assembly factor ACDH-12 in Caenorhabditis elegans.

    PubMed

    Chuaijit, Sirithip; Boonyatistan, Worawit; Boonchuay, Pichsinee; Metheetrairut, Chanatip; Suthammarak, Wichit

    2018-03-11

    Assembly of complex I of the mitochondrial respiratory chain (MRC) requires not only structural subunits for electron transport, but also assembly factors. In the nematode Caenorhabditis elegans, NUAF-1 and NUAF-3 are the only two assembly factors that have been characterized. In this study, we identify ACDH-12 as an assembly factor of the respiratory complex I. We demonstrate for the first time that a deficiency of ACDH-12 affects the formation and function of complex I. RNAi knockdown of acdh-12 also shortens lifespan and decreases fecundity. Although ACDH-12 has long been recognized as a very long-chain acyl-CoA dehydrogenase (VLCAD), the knockdown nematodes did not exhibit any change in body fat content. We suggested that in Caenorhabditis elegans, ACDH-12 is required for the assembly of the respiratory complex I, but may not be crucial to fatty acid oxidation. Interestingly, sequence analysis shows high homology between ACDH-12 and the human ACAD9, a protein that has initially been identified as a VLCAD, but later found to also be involved in the assembly of complex I in human. Copyright © 2018 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

  7. Vortex formation in a complex plasma

    NASA Astrophysics Data System (ADS)

    Ishihara, Osamu

    Complex plasma experiments in ground-based laboratories as well as in microgravity conditions have shown the formation of vortex structures in various conditions (e.g., 1,2,3,4). The vortex structures formed in a complex plasma are visible by naked eyes with the help of irradiating laser and the individual dust particles in the structure give us the opportunity to study detailed physics of the commonly observed natural phenomena known such as tornadoes, typhoons, hurricanes and dust devils. Based on the Navier-Stokes equation with proper complex plasma conditions we analyze as much as possible in a universal way the vortex structure and clarifies the role of the controlling parameters like flow velocity and external magnetic field. 1. G. E. Morfill,H. M. Thomas, U. Konopka,H. Rothermel, M. Zuzic, A. Ivlev, and J. Goree, Phys,. Rev. Lett. 83, 1598 (1999). 2. E. Nebbat and R. Annou, Phys. Plasmas 17, 093702 (2010). 3. Y. Saitou and O. Ishihara, Phys. Rev. Lett. 111, 185003 (2013). 4. V. N. Tsytovich and N. G. Gusein-zade, Plasma Phys. Rep. 39, 515 (2013).

  8. A Model Incorporating Some of the Mechanical and Biochemical Factors Underlying Clot Formation and Dissolution in Flowing Blood

    DOE PAGES

    Anand, M.; Rajagopal, K.; Rajagopal, K. R.

    2003-01-01

    Multiple interacting mechanisms control the formation and dissolution of clots to maintain blood in a state of delicate balance. In addition to a myriad of biochemical reactions, rheological factors also play a crucial role in modulating the response of blood to external stimuli. To date, a comprehensive model for clot formation and dissolution, that takes into account the biochemical, medical and rheological factors, has not been put into place, the existing models emphasizing either one or the other of the factors. In this paper, after discussing the various biochemical, physiologic and rheological factors at some length, we develop a modelmore » for clot formation and dissolution that incorporates many of the relevant crucial factors that have a bearing on the problem. The model, though just a first step towards understanding a complex phenomenon, goes further than previous models in integrating the biochemical, physiologic and rheological factors that come into play.« less

  9. Pattern Formation and Complexity Emergence

    NASA Astrophysics Data System (ADS)

    Berezin, Alexander A.

    2001-03-01

    Success of nonlinear modelling of pattern formation and self-organization encourages speculations on informational and number theoretical foundations of complexity emergence. Pythagorean "unreasonable effectiveness of integers" in natural processes is perhaps extrapolatable even to universal emergence "out-of-nothing" (Leibniz, Wheeler). Because rational numbers (R = M/N) are everywhere dense on real axis, any digital string (hence any "book" from "Library of Babel" of J.L.Borges) is "recorded" infinitely many times in arbitrary many rationals. Furthermore, within any arbitrary small interval there are infinitely many Rs for which (either or both) integers (Ms and Ns) "carry" any given string of any given length. Because any iterational process (such as generation of fractal features of Mandelbrot Set) is arbitrary closely approximatable with rational numbers, the infinite pattern of integers expresses itself in generation of complexity of the world, as well as in emergence of the world itself. This "tunnelling" from Platonic World ("Platonia" of J.Barbour) to a real (physical) world is modern recast of Leibniz's motto ("for deriving all from nothing there suffices a single principle").

  10. Demixing-stimulated lane formation in binary complex plasma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Du, C.-R.; Jiang, K.; Suetterlin, K. R.

    2011-11-29

    Recently lane formation and phase separation have been reported for experiments with binary complex plasmas in the PK3-Plus laboratory onboard the International Space Station (ISS). Positive non-additivity of particle interactions is known to stimulate phase separation (demixing), but its effect on lane formation is unknown. In this work, we used Langevin dynamics (LD) simulation to probe the role of non-additivity interactions on lane formation. The competition between laning and demixing leads to thicker lanes. Analysis based on anisotropic scaling indices reveals a crossover from normal laning mode to a demixing-stimulated laning mode. Extensive numerical simulations enabled us to identify amore » critical value of the non-additivity parameter {Delta} for the crossover.« less

  11. Gel phase formation in dilute triblock copolyelectrolyte complexes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Srivastava, Samanvaya; Andreev, Marat; Levi, Adam E.

    Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chainmore » aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.« less

  12. Gel phase formation in dilute triblock copolyelectrolyte complexes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Srivastava, Samanvaya; Andreev, Marat; Levi, Adam E.

    Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chainmore » aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Finally, our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.« less

  13. Gel phase formation in dilute triblock copolyelectrolyte complexes

    DOE PAGES

    Srivastava, Samanvaya; Andreev, Marat; Levi, Adam E.; ...

    2017-02-23

    Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chainmore » aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Finally, our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.« less

  14. Gel Phase Formation in Dilute Triblock Copolyelectrolyte Complexes

    NASA Astrophysics Data System (ADS)

    Srivastava, Samanvaya; Andreev, Marat; Prabhu, Vivek; de Pablo, Juan; Tirrell, Matthew

    Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at extremely low polymer concentrations (<1 % by mass) has been observed in scattering experiments and molecular dynamics simulations. In contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing polymer concentrations, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assemblies of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously upon solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chain aggregates in early stages of triblock copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries not only contribute to our fundamental understanding of the structure and pathways of complexation driven assemblies, but also raise intriguing prospects for formation of gel structures at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.

  15. Gel phase formation in dilute triblock copolyelectrolyte complexes

    NASA Astrophysics Data System (ADS)

    Srivastava, Samanvaya; Andreev, Marat; Levi, Adam E.; Goldfeld, David J.; Mao, Jun; Heller, William T.; Prabhu, Vivek M.; de Pablo, Juan J.; Tirrell, Matthew V.

    2017-02-01

    Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chain aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.

  16. Ectopic expression of R3 MYB transcription factor gene OsTCL1 in Arabidopsis, but not rice, affects trichome and root hair formation

    PubMed Central

    Zheng, Kaijie; Tian, Hainan; Hu, Qingnan; Guo, Hongyan; Yang, Li; Cai, Ling; Wang, Xutong; Liu, Bao; Wang, Shucai

    2016-01-01

    In Arabidopsis, a MYB-bHLH-WD40 (MBW) transcriptional activator complex activates the homeodomain protein gene GLABRA2 (GL2), leading to the promotion of trichome formation and inhibition of root hair formation. The same MBW complex also activates single-repeat R3 MYB genes. R3 MYBs in turn, play a negative feedback role by competing with R2R3 MYB proteins for binding bHLH proteins, thus blocking the formation of the MBW complex. By BLASTing the rice (Oryza sativa) protein database using the entire amino acid sequence of Arabidopsis R3 MYB transcription factor TRICHOMELESS1 (TCL1), we found that there are two genes in rice genome encoding R3 MYB transcription factors, namely Oryza sativa TRICHOMELESS1 (OsTCL1) and OsTCL2. Expressing OsTCL1 in Arabidopsis inhibited trichome formation and promoted root hair formation, and OsTCL1 interacted with GL3 when tested in Arabidopsis protoplasts. Consistent with these observations, expression levels of GL2, R2R3 MYB transcription factor gene GLABRA1 (GL1) and several R3 MYB genes were greatly reduced, indicating that OsTCL1 is functional R3 MYB. However, trichome and root hair formation in transgenic rice plants overexpressing OsTCL1 remained largely unchanged, and elevated expression of OsGL2 was observed in the transgenic rice plants, indicating that rice may use different mechanisms to regulate trichome formation. PMID:26758286

  17. Formative feedback and scaffolding for developing complex problem solving and modelling outcomes

    NASA Astrophysics Data System (ADS)

    Frank, Brian; Simper, Natalie; Kaupp, James

    2018-07-01

    This paper discusses the use and impact of formative feedback and scaffolding to develop outcomes for complex problem solving in a required first-year course in engineering design and practice at a medium-sized research-intensive Canadian university. In 2010, the course began to use team-based, complex, open-ended contextualised problems to develop problem solving, communications, teamwork, modelling, and professional skills. Since then, formative feedback has been incorporated into: task and process-level feedback on scaffolded tasks in-class, formative assignments, and post-assignment review. Development in complex problem solving and modelling has been assessed through analysis of responses from student surveys, direct criterion-referenced assessment of course outcomes from 2013 to 2015, and an external longitudinal study. The findings suggest that students are improving in outcomes related to complex problem solving over the duration of the course. Most notably, the addition of new feedback and scaffolding coincided with improved student performance.

  18. Dynamics of nanoparticle-protein corona complex formation: analytical results from population balance equations.

    PubMed

    Darabi Sahneh, Faryad; Scoglio, Caterina; Riviere, Jim

    2013-01-01

    Nanoparticle-protein corona complex formation involves absorption of protein molecules onto nanoparticle surfaces in a physiological environment. Understanding the corona formation process is crucial in predicting nanoparticle behavior in biological systems, including applications of nanotoxicology and development of nano drug delivery platforms. This paper extends the modeling work in to derive a mathematical model describing the dynamics of nanoparticle corona complex formation from population balance equations. We apply nonlinear dynamics techniques to derive analytical results for the composition of nanoparticle-protein corona complex, and validate our results through numerical simulations. The model presented in this paper exhibits two phases of corona complex dynamics. In the first phase, proteins rapidly bind to the free surface of nanoparticles, leading to a metastable composition. During the second phase, continuous association and dissociation of protein molecules with nanoparticles slowly changes the composition of the corona complex. Given sufficient time, composition of the corona complex reaches an equilibrium state of stable composition. We find analytical approximate formulae for metastable and stable compositions of corona complex. Our formulae are very well-structured to clearly identify important parameters determining corona composition. The dynamics of biocorona formation constitute vital aspect of interactions between nanoparticles and living organisms. Our results further understanding of these dynamics through quantitation of experimental conditions, modeling results for in vitro systems to better predict behavior for in vivo systems. One potential application would involve a single cell culture medium related to a complex protein medium, such as blood or tissue fluid.

  19. GDP-mannose-4,6-dehydratase (GMDS) Deficiency Renders Colon Cancer Cells Resistant to Tumor Necrosis Factor-related Apoptosis-inducing Ligand (TRAIL) Receptor- and CD95-mediated Apoptosis by Inhibiting Complex II Formation*

    PubMed Central

    Moriwaki, Kenta; Shinzaki, Shinichiro; Miyoshi, Eiji

    2011-01-01

    Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis through binding to TRAIL receptors, death receptor 4 (DR4), and DR5. TRAIL has potential therapeutic value against cancer because of its selective cytotoxic effects on several transformed cell types. Fucosylation of proteins and lipids on the cell surface is a very important posttranslational modification that is involved in many cellular events. Recently, we found that a deficiency in GDP-mannose-4,6-dehydratase (GMDS) rendered colon cancer cells resistant to TRAIL-induced apoptosis, resulting in tumor development and metastasis by escape from tumor immune surveillance. GMDS is an indispensable regulator of cellular fucosylation. In this study, we investigated the molecular mechanism of inhibition of TRAIL signaling by GMDS deficiency. DR4, but not DR5, was found to be fucosylated; however, GMDS deficiency inhibited both DR4- and DR5-mediated apoptosis despite the absence of fucosylation on DR5. In addition, GMDS deficiency also inhibited CD95-mediated apoptosis but not the intrinsic apoptosis pathway induced by anti-cancer drugs. Binding of TRAIL and CD95 ligand to their cognate receptors primarily leads to formation of a complex comprising the receptor, FADD, and caspase-8, referred to as the death-inducing signaling complex (DISC). GMDS deficiency did not affect formation of the primary DISC or recruitment to and activation of caspase-8 on the DISC. However, formation of secondary FADD-dependent complex II, comprising caspase-8 and cFLIP, was significantly inhibited by GMDS deficiency. These results indicate that GMDS regulates the formation of secondary complex II from the primary DISC independent of direct fucosylation of death receptors. PMID:22027835

  20. Formation kinetics and mechanism of metastable vacancy-dioxygen complex in neutron irradiated Czochralski silicon

    NASA Astrophysics Data System (ADS)

    Dong, Peng; Wang, Rong; Yu, Xuegong; Chen, Lin; Ma, Xiangyang; Yang, Deren

    2017-07-01

    We have quantitatively investigated the formation kinetics of metastable vacancy-dioxygen (VO2) complex in a structure of [VO + Oi], where a VO complex is trapped in a next-neighbor position to an interstitial oxygen atom (Oi). It is found that the VO annihilation is accompanied by the generation of metastable [VO + Oi] complex during annealing in the temperature range of 220-250 °C. The activation energy for [VO + Oi] generation appears at around 0.48 eV, which is much lower than the counterpart of stable VO2 complex. This indicates that the formation of [VO + Oi] complex originates from the reaction between VO and Oi. The ab initio calculations show that the formation energy of [VO + Oi] complex is larger than that of VO2 complex, which means that [VO + Oi] complex is thermodynamically unfavorable as compared to VO2 complex. However, the binding energy of [VO + Oi] complex is positive, indicating that [VO + Oi] complex is stable against decomposition of VO and Oi in silicon. It is believed that [VO + Oi] complex serves as the intermediate for VO to VO2 conversion.

  1. A Developmental Framework for Complex Plasmodesmata Formation Revealed by Large-Scale Imaging of the Arabidopsis Leaf Epidermis[W

    PubMed Central

    Fitzgibbon, Jessica; Beck, Martina; Zhou, Ji; Faulkner, Christine; Robatzek, Silke; Oparka, Karl

    2013-01-01

    Plasmodesmata (PD) form tubular connections that function as intercellular communication channels. They are essential for transporting nutrients and for coordinating development. During cytokinesis, simple PDs are inserted into the developing cell plate, while during wall extension, more complex (branched) forms of PD are laid down. We show that complex PDs are derived from existing simple PDs in a pattern that is accelerated when leaves undergo the sink–source transition. Complex PDs are inserted initially at the three-way junctions between epidermal cells but develop most rapidly in the anisocytic complexes around stomata. For a quantitative analysis of complex PD formation, we established a high-throughput imaging platform and constructed PDQUANT, a custom algorithm that detected cell boundaries and PD numbers in different wall faces. For anticlinal walls, the number of complex PDs increased with increasing cell size, while for periclinal walls, the number of PDs decreased. Complex PD insertion was accelerated by up to threefold in response to salicylic acid treatment and challenges with mannitol. In a single 30-min run, we could derive data for up to 11k PDs from 3k epidermal cells. This facile approach opens the door to a large-scale analysis of the endogenous and exogenous factors that influence PD formation. PMID:23371949

  2. Complexes of horseradish peroxidase with formate, acetate, and carbon monoxide.

    PubMed

    Carlsson, Gunilla H; Nicholls, Peter; Svistunenko, Dimitri; Berglund, Gunnar I; Hajdu, Janos

    2005-01-18

    Carbon monoxide, formate, and acetate interact with horseradish peroxidase (HRP) by binding to subsites within the active site. These ligands also bind to catalases, but their interactions are different in the two types of enzymes. Formate (notionally the "hydrated" form of carbon monoxide) is oxidized to carbon dioxide by compound I in catalase, while no such reaction is reported to occur in HRP, and the CO complex of ferrocatalase can only be obtained indirectly. Here we describe high-resolution crystal structures for HRP in its complexes with carbon monoxide and with formate, and compare these with the previously determined HRP-acetate structure [Berglund, G. I., et al. (2002) Nature 417, 463-468]. A multicrystal X-ray data collection strategy preserved the correct oxidation state of the iron during the experiments. Absorption spectra of the crystals and electron paramagnetic resonance data for the acetate and formate complexes in solution correlate electronic states with the structural results. Formate in ferric HRP and CO in ferrous HRP bind directly to the heme iron with iron-ligand distances of 2.3 and 1.8 A, respectively. CO does not bind to the ferric iron in the crystal. Acetate bound to ferric HRP stacks parallel with the heme plane with its carboxylate group 3.6 A from the heme iron, and without an intervening solvent molecule between the iron and acetate. The positions of the oxygen atoms in the bound ligands outline a potential access route for hydrogen peroxide to the iron. We propose that interactions in this channel ensure deprotonation of the proximal oxygen before binding to the heme iron.

  3. Dynamics of Nanoparticle-Protein Corona Complex Formation: Analytical Results from Population Balance Equations

    PubMed Central

    Darabi Sahneh, Faryad; Scoglio, Caterina; Riviere, Jim

    2013-01-01

    Background Nanoparticle-protein corona complex formation involves absorption of protein molecules onto nanoparticle surfaces in a physiological environment. Understanding the corona formation process is crucial in predicting nanoparticle behavior in biological systems, including applications of nanotoxicology and development of nano drug delivery platforms. Method This paper extends the modeling work in to derive a mathematical model describing the dynamics of nanoparticle corona complex formation from population balance equations. We apply nonlinear dynamics techniques to derive analytical results for the composition of nanoparticle-protein corona complex, and validate our results through numerical simulations. Results The model presented in this paper exhibits two phases of corona complex dynamics. In the first phase, proteins rapidly bind to the free surface of nanoparticles, leading to a metastable composition. During the second phase, continuous association and dissociation of protein molecules with nanoparticles slowly changes the composition of the corona complex. Given sufficient time, composition of the corona complex reaches an equilibrium state of stable composition. We find analytical approximate formulae for metastable and stable compositions of corona complex. Our formulae are very well-structured to clearly identify important parameters determining corona composition. Conclusion The dynamics of biocorona formation constitute vital aspect of interactions between nanoparticles and living organisms. Our results further understanding of these dynamics through quantitation of experimental conditions, modeling results for in vitro systems to better predict behavior for in vivo systems. One potential application would involve a single cell culture medium related to a complex protein medium, such as blood or tissue fluid. PMID:23741371

  4. Correlations between Community Structure and Link Formation in Complex Networks

    PubMed Central

    Liu, Zhen; He, Jia-Lin; Kapoor, Komal; Srivastava, Jaideep

    2013-01-01

    Background Links in complex networks commonly represent specific ties between pairs of nodes, such as protein-protein interactions in biological networks or friendships in social networks. However, understanding the mechanism of link formation in complex networks is a long standing challenge for network analysis and data mining. Methodology/Principal Findings Links in complex networks have a tendency to cluster locally and form so-called communities. This widely existed phenomenon reflects some underlying mechanism of link formation. To study the correlations between community structure and link formation, we present a general computational framework including a theory for network partitioning and link probability estimation. Our approach enables us to accurately identify missing links in partially observed networks in an efficient way. The links having high connection likelihoods in the communities reveal that links are formed preferentially to create cliques and accordingly promote the clustering level of the communities. The experimental results verify that such a mechanism can be well captured by our approach. Conclusions/Significance Our findings provide a new insight into understanding how links are created in the communities. The computational framework opens a wide range of possibilities to develop new approaches and applications, such as community detection and missing link prediction. PMID:24039818

  5. Formation of Stable Cationic Lipid/DNA Complexes for Gene Transfer

    NASA Astrophysics Data System (ADS)

    Hofland, Hans E. J.; Shephard, Lee; Sullivan, Sean M.

    1996-07-01

    Stable cationic lipid/DNA complexes were formed by solubilizing cationic liposomes with 1% octylglucoside and complexing a DNA plasmid with the lipid in the presence of detergent. Removal of the detergent by dialysis yielded a lipid/DNA suspension that was able to transfect tissue culture cells up to 90 days after formation with no loss in activity. Similar levels of gene transfer were obtained by mixing the cationic lipid in a liposome form with DNA just prior to cell addition. However, expression was completely lost 24 hr after mixing. The transfection efficiency of the stable complex in 15% fetal calf serum was 30% of that obtained in the absence of serum, whereas the transient complex was completely inactivated with 2% fetal calf serum. A 90-day stability study comparing various storage conditions showed that the stable complex could be stored frozen or as a suspension at 4 degrees C with no loss in transfection efficiency. Centrifugation of the stable complex produced a pellet that contained approximately 90% of the DNA and 10% of the lipid. Transfection of cells with the resuspended pellet and the supernatant showed that the majority of the transfection activity was in the pellet and all the toxicity was in the supernatant. Formation of a stable cationic lipid/DNA complex has produced a transfection vehicle that can be stored indefinitely, can be concentrated with no loss in transfection efficiency, and the toxicity levels can be greatly reduced when the active complex is isolated from the uncomplexed lipid.

  6. Study on the mechanism of copper-ammonia complex decomposition in struvite formation process and enhanced ammonia and copper removal.

    PubMed

    Peng, Cong; Chai, Liyuan; Tang, Chongjian; Min, Xiaobo; Song, Yuxia; Duan, Chengshan; Yu, Cheng

    2017-01-01

    Heavy metals and ammonia are difficult to remove from wastewater, as they easily combine into refractory complexes. The struvite formation method (SFM) was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia. The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion. Ammonia was separated from solution as crystalline struvite, and the copper mainly co-precipitated as copper hydroxide together with struvite. Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide. Hydrogen bonding was concluded to be the key factor leading to the co-precipitation. In addition, incorporation of copper ions into the struvite crystal also occurred during the treatment process. Copyright © 2016. Published by Elsevier B.V.

  7. Ternary complex formation of Eu(III) with o-phthalate in aqueous solutions.

    PubMed

    Park, K K; Jung, E C; Cho, H-R; Kim, W H

    2009-08-15

    Ternary hydroxo complex formation of Eu(III) with o-phthalate was investigated by potentiometry and fluorescence spectrophotometry. Curves of the equilibrium pH versus the amount of NaOH added showed that the pH value starting to form a Eu(III) precipitate was decreased due to the formation of a ternary hydroxo complex, EuOHL(s) (L = phthalate). The formation of EuOHL(s) was qualitatively confirmed by the enhancement of the fluorescence intensity of Eu(III) in the precipitate with the light absorbed by phthalate, and was quantitatively confirmed by the measurement of the amounts of Eu(III), OH(-) and phthalate included in the precipitate. The solubility product of EuOHL(s) was determined as pK(sp)(0) = 15.6+/-0.4. Characteristic features in the fluorescence spectra and the solubility product of the Eu(III)-phthalate complex were compared with those of the Eu(III)-PDA (PDA = pyridine-2,6-dicarboxylate) complex. The fluorescence intensity of the EuL(+) complex of L = PDA was about 11 times stronger than that of L = phthalate. The origin of the difference in the fluorescence intensity is discussed based on the intramolecular energy transfer effect from the lowest triplet energy level of the ligand to the resonance energy level of Eu(III).

  8. Factors Influencing Biofilm Formation in Streams: Bacterial Colonization, Detachment and Transport

    NASA Astrophysics Data System (ADS)

    Leff, L.

    2005-05-01

    Surfaces in aquatic systems develop biofilms containing microorganisms embedded in complex extracellular matrices. Properties of the surface, water, and colonizing organisms impact biofilm formation. Biofilm features, physical disturbance, and interactions between macro- and microscopic organisms, in turn, influence detachment. In spite of the importance of biofilms, much remains unknown about factors controlling biofilms in streams and other natural environments. Experiments were conducted in the laboratory and field to examine factors influencing surface colonization, and subsequent biofilm formation, and detachment. Microscopy methods, fluorescent in situ hybridization and confocal laser microscopy, were used to examine responses, including abundance of different taxa and biofilm depth. From these experiments, we determined that different taxa differ in their colonization ability based on properties like extracellular polysaccharide production and surface features, like hydrophobicity and that water chemistry, such as magnesium concentration, plays an important role. Moreover, detachment varies among taxa and with environmental conditions and may be enhanced by activities of macrofauna. Variation in detachment, in turn, influences bacterial transport and subsequent re-attachment. Overall, examination of attachment, detachment, and interactions in biofilms allows us to begin to understand how environmental conditions may impact the function of these communities in aquatic systems.

  9. Pathway of actin filament branch formation by Arp2/3 complex revealed by single-molecule imaging

    PubMed Central

    Smith, Benjamin A.; Daugherty-Clarke, Karen; Goode, Bruce L.; Gelles, Jeff

    2013-01-01

    Actin filament nucleation by actin-related protein (Arp) 2/3 complex is a critical process in cell motility and endocytosis, yet key aspects of its mechanism are unknown due to a lack of real-time observations of Arp2/3 complex through the nucleation process. Triggered by the verprolin homology, central, and acidic (VCA) region of proteins in the Wiskott-Aldrich syndrome protein (WASp) family, Arp2/3 complex produces new (daughter) filaments as branches from the sides of preexisting (mother) filaments. We visualized individual fluorescently labeled Arp2/3 complexes dynamically interacting with and producing branches on growing actin filaments in vitro. Branch formation was strikingly inefficient, even in the presence of VCA: only ∼1% of filament-bound Arp2/3 complexes yielded a daughter filament. VCA acted at multiple steps, increasing both the association rate of Arp2/3 complexes with mother filament and the fraction of filament-bound complexes that nucleated a daughter. The results lead to a quantitative kinetic mechanism for branched actin assembly, revealing the steps that can be stimulated by additional cellular factors. PMID:23292935

  10. Biliary bacterial factors determine the path of gallstone formation.

    PubMed

    Stewart, Lygia; Grifiss, J McLeod; Jarvis, Gary A; Way, Lawrence W

    2006-11-01

    Bacteria cause pigment gallstones and can act as a nidus for cholesterol gallstone formation. Bacterial factors that facilitate gallstone formation include beta-glucuronidase (bG), phospholipase (PhL), and slime. The current study sought to determine whether bacterial factors influence the path of gallstone formation. A total of 382 gallstones were cultured and/or examined using scanning electron microscopy (SEM). Bacteria were tested for bG and slime production. Gallstone composition was determined using infrared spectrography. Ca-palmitate presence documented bacterial PhL production. Groups were identified based upon bacterial factors present: slime and bGPhL (slime/bGPhL), bGPhL only, and slime only. Influence of bacterial stone-forming factors on gallstone composition and morphology was analyzed. Bacteria were present in 75% of pigment, 76% of mixed, and 20% of cholesterol stones. Gallstones with bGPhL producing bacteria contained more pigment (71% vs. 26%, P < .0001). The slime/bGPhL group was associated (79%) with pigment stones, bGPhL was associated (56%) with mixed stones, while slime (or none) only was associated (67%) with cholesterol stones (P < .031, all comparisons). Bacterial properties determined the path of gallstone formation. Bacteria that produced all stone-forming factors promoted pigment stone formation, while those that produced only bGPhL promoted mixed stone formation. Bacteria that only produced slime lacked the ability to generate pigment solids, and consequently were more common in the centers of cholesterol stones. This shows how bacterial characteristics may govern the process of gallstone formation.

  11. Role of G protein signaling in the formation of the fibrin(ogen)-integrin αIIbβ3-actin cytoskeleton complex in platelets.

    PubMed

    Budnik, Ivan; Shenkman, Boris; Savion, Naphtali

    2016-09-01

    Effective platelet function requires formation of a physical link between fibrin(ogen), integrin αIIbβ3, and cytoplasmic actin filaments. We investigated the role of the Gαq, Gαi, and Gα12/13 families of heterotrimeric GTP-binding proteins (G proteins) in the assembly of a ligand-αIIbβ3-actin cytoskeleton complex. Selective and combined activation of the G proteins was achieved by using combinations of various platelet agonists and inhibitors. Formation and stability of fibrinogen-αIIbβ3 interaction were evaluated by the extent of platelet aggregation and the rate of eptifibatide-induced platelet disaggregation; association of αIIbβ3 with the cytoskeleton was analyzed by western blot. Formation of the fibrin-αIIbβ3-actin cytoskeleton complex was evaluated by rotational thromboelastometry assay in which clot formation was induced by the mixture of reptilase and factor XIIIa. We demonstrated that involvement of heterotrimeric G proteins in the formation of the ligand-αIIbβ3-cytoskeleton complex depends on whether fibrinogen or fibrin serves as the integrin ligand. Formation of the fibrinogen-αIIbβ3-cytoskeleton complex requires combined activation of at least two G protein pathways while the maximal αIIbβ3-cytoskeleton association and the strongest αIIbβ3-fibrinogen binding supporting irreversible platelet aggregation require combined activation of all three-Gαq, Gαi, and Gα12/13-G protein families. In contrast, formation of the fibrin-αIIbβ3-cytoskeleton complex mediating clot retraction is critically dependent on the activation of the Gαi family, especially on the activation of Gαz.

  12. Sunlight assisted direct amide formation via a charge-transfer complex.

    PubMed

    Cohen, Irit; Mishra, Abhaya K; Parvari, Galit; Edrei, Rachel; Dantus, Mauricio; Eichen, Yoav; Szpilman, Alex M

    2017-09-12

    We report on the use of charge-transfer complexes between amines and carbon tetrachloride, as a novel way to activate the amine for photochemical reactions. This principle is demonstrated in a mild, transition metal free, visible light assisted, dealkylative amide formation from feedstock carboxylic acids and amines. The low absorption coefficient of the complex allows deep light penetration and thus scale up to a gram scale.

  13. A botulinum neurotoxin-like function of Potentilla chinensis extract that inhibits neuronal SNARE complex formation, membrane fusion, neuroexocytosis, and muscle contraction.

    PubMed

    Jung, Chang-Hwa; Choi, Jin-Kyu; Yang, Yoosoo; Koh, Hyun-Ju; Heo, Paul; Yoon, Kee-Jung; Kim, Sehyun; Park, Won-Seok; Shing, Hong-Ju; Kweon, Dae-Hyuk

    2012-09-01

    Botulinum neurotoxins (BoNTs) are popularly used to treat various diseases and for cosmetic purposes. They act by blocking neurotransmission through specific cleavage of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. Recently, several polyphenols were shown to interfere with SNARE complex formation by wedging into the hydrophobic core interface, thereby leading to reduced neuroexocytosis. In order to find industrially-viable plant extract that functions like BoNT, 71 methanol extracts of flowers were screened and BoNT-like activity of selected extract was evaluated. After evaluating the inhibitory effect of 71 flower methanol extracts on SNARE complex formation, seven candidates were selected and they were subjected to SNARE-driven membrane fusion assay. Neurotransmitter release from neuronal PC12 cells and SNARE complex formation inside the cell was also evaluated. Finally, the effect of one selected extract on muscle contraction and digit abduction score was determined. The extract of Potentilla chinensis Ser. (Rosaceae)(Chinese cinquefoil) flower inhibited neurotransmitter release from neuronal PC12 cells by approximately 90% at a concentration of 10 μg/mL. The extract inhibited neuroexocytosis by interfering with SNARE complex formation inside cells. It reduced muscle contraction of phrenic nerve-hemidiaphragm by approximately 70% in 60 min, which is comparable to the action of the Ca²⁺-channel blocker verapamil and BoNT type A. While BoNT blocks neuroexocytosis by cleaving SNARE proteins, the Potentilla chinensis extract exhibited the same activity by inhibiting SNARE complex formation. The extract paralyzed muscle as efficiently as BoNT, suggesting the potential versatility in cosmetics and therapeutics.

  14. Functional Synergy between Rab5 Effector Rabaptin-5 and Exchange Factor Rabex-5 When Physically Associated in a Complex

    PubMed Central

    Lippé, Roger; Miaczynska, Marta; Rybin, Vladimir; Runge, Anja; Zerial, Marino

    2001-01-01

    Rab GTPases are central elements of the vesicular transport machinery. An emerging view is that downstream effectors of these GTPases are multiprotein complexes that include nucleotide exchange factors to ensure coupling between GTPase activation and effector function. We have previously shown that Rab5, which regulates various steps of transport along the early endocytic pathway, is activated by a complex consisting of Rabex-5, a Rab5 nucleotide exchange factor, and the effector Rabaptin-5. We postulated that the physical association of these two proteins is necessary for their activity in Rab5-dependent endocytic membrane transport. To evaluate the functional implications of such complex formation, we have reconstituted it with the use of recombinant proteins and characterized its properties. First, we show that Rabaptin-5 increases the exchange activity of Rabex-5 on Rab5. Second, Rab5-dependent recruitment of Rabaptin-5 to early endosomes is completely dependent on its physical association with Rabex-5. Third, complex formation between Rabaptin-5 and Rabex-5 is essential for early endosome homotypic fusion. These results reveal a functional synergy between Rabaptin-5 and Rabex-5 in the complex and have implications for the function of analogous complexes for Rab and Rho GTPases. PMID:11452015

  15. The C Terminus of the Saccharomyces cerevisiae α-Factor Receptor Contributes to the Formation of Preactivation Complexes with Its Cognate G Protein

    PubMed Central

    Dosil, Mercedes; Schandel, Kimberly A.; Gupta, Ekta; Jenness, Duane D.; Konopka, James B.

    2000-01-01

    Binding of the α-factor pheromone to its G-protein-coupled receptor (encoded by STE2) activates the mating pathway in MATa yeast cells. To investigate whether specific interactions between the receptor and the G protein occur prior to ligand binding, we analyzed dominant-negative mutant receptors that compete with wild-type receptors for G proteins, and we analyzed the ability of receptors to suppress the constitutive signaling activity of mutant Gα subunits in an α-factor-independent manner. Although the amino acid substitution L236H in the third intracellular loop of the receptor impairs G-protein activation, this substitution had no influence on the ability of the dominant-negative receptors to sequester G proteins or on the ability of receptors to suppress the GPA1-A345T mutant Gα subunit. In contrast, removal of the cytoplasmic C-terminal domain of the receptor eliminated both of these activities even though the C-terminal domain is unnecessary for G-protein activation. Moreover, the α-factor-independent signaling activity of ste2-P258L mutant receptors was inhibited by the coexpression of wild-type receptors but not by coexpression of truncated receptors lacking the C-terminal domain. Deletion analysis suggested that the distal half of the C-terminal domain is critical for sequestration of G proteins. The C-terminal domain was also found to influence the affinity of the receptor for α-factor in cells lacking G proteins. These results suggest that the C-terminal cytoplasmic domain of the α-factor receptor, in addition to its role in receptor downregulation, promotes the formation of receptor–G-protein preactivation complexes. PMID:10866688

  16. The Ferredoxin-Like Proteins HydN and YsaA Enhance Redox Dye-Linked Activity of the Formate Dehydrogenase H Component of the Formate Hydrogenlyase Complex.

    PubMed

    Pinske, Constanze

    2018-01-01

    Formate dehydrogenase H (FDH-H) and [NiFe]-hydrogenase 3 (Hyd-3) form the catalytic components of the hydrogen-producing formate hydrogenlyase (FHL) complex, which disproportionates formate to H 2 and CO 2 during mixed acid fermentation in enterobacteria. FHL comprises minimally seven proteins and little is understood about how this complex is assembled. Early studies identified a ferredoxin-like protein, HydN, as being involved in FDH-H assembly into the FHL complex. In order to understand how FDH-H and its small subunit HycB, which is also a ferredoxin-like protein, attach to the FHL complex, the possible roles of HydN and its paralogue, YsaA, in FHL complex stability and assembly were investigated. Deletion of the hycB gene reduced redox dye-mediated FDH-H activity to approximately 10%, abolished FHL-dependent H 2 -production, and reduced Hyd-3 activity. These data are consistent with HycB being an essential electron transfer component of the FHL complex. The FDH-H activity of the hydN and the ysaA deletion strains was reduced to 59 and 57% of the parental, while the double deletion reduced activity of FDH-H to 28% and the triple deletion with hycB to 1%. Remarkably, and in contrast to the hycB deletion, the absence of HydN and YsaA was without significant effect on FHL-dependent H 2 -production or total Hyd-3 activity; FDH-H protein levels were also unaltered. This is the first description of a phenotype for the E. coli ysaA deletion strain and identifies it as a novel factor required for optimal redox dye-linked FDH-H activity. A ysaA deletion strain could be complemented for FDH-H activity by hydN and ysaA , but the hydN deletion strain could not be complemented. Introduction of these plasmids did not affect H 2 production. Bacterial two-hybrid interactions showed that YsaA, HydN, and HycB interact with each other and with the FDH-H protein. Further novel anaerobic cross-interactions of 10 ferredoxin-like proteins in E. coli were also discovered and described

  17. A novel germ cell protein, SPIF (sperm PKA interacting factor), is essential for the formation of a PKA/TCP11 complex that undergoes conformational and phosphorylation changes upon capacitation.

    PubMed

    Stanger, Simone J; Law, Estelle A; Jamsai, Duangporn; O'Bryan, Moira K; Nixon, Brett; McLaughlin, Eileen A; Aitken, R John; Roman, Shaun D

    2016-08-01

    Spermatozoa require the process of capacitation to enable them to fertilize an egg. PKA is crucial to capacitation and the development of hyperactivated motility. Sperm PKA is activated by cAMP generated by the germ cell-enriched adenylyl cyclase encoded by Adcy10 Male mice lacking Adcy10 are sterile, because their spermatozoa are immotile. The current study was designed to identify binding partners of the sperm-specific (Cα2) catalytic subunit of PKA (PRKACA) by using it as the "bait" in a yeast 2-hybrid system. This approach was used to identify a novel germ cell-enriched protein, sperm PKA interacting factor (SPIF), in 25% of the positive clones. Homozygous Spif-null mice were embryonically lethal. SPIF was coexpressed and coregulated with PRKACA and with t-complex protein (TCP)-11, a protein associated with PKA signaling. We established that these 3 proteins form part of a novel complex in mouse spermatozoa. Upon capacitation, the SPIF protein becomes tyrosine phosphorylated in >95% of sperm. An apparent molecular rearrangement in the complex occurs, bringing PRKACA and TCP11 into proximity. Taken together, these results suggest a role for the novel complex of SPIF, PRKACA, and TCP11 during sperm capacitation, fertilization, and embryogenesis.-Stanger, S. J., Law, E. A., Jamsai, D., O'Bryan, M. K., Nixon, B., McLaughlin, E. A., Aitken, R. J., Roman, S. D. A novel germ cell protein, SPIF (sperm PKA interacting factor), is essential for the formation of a PKA/TCP11 complex that undergoes conformational and phosphorylation changes upon capacitation. © FASEB.

  18. Pattern formation based on complex coupling mechanism in dielectric barrier discharge

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Weibo; College of Aeronautical Engineering, Binzhou University, Binzhou 256603; Dong, Lifang, E-mail: donglfhbu@163.com, E-mail: pyy1616@163.com

    2016-08-15

    The pattern formation of cinque-dice square superlattice pattern (CDSSP) is investigated based on the complex coupling mechanism in a dielectric barrier discharge (DBD) system. The spatio-temporal structure of CDSSP obtained by using an intensified-charge coupled device indicates that CDSSP is an interleaving of two kinds of subpatterns (mixture of rectangle and square, and dot-line square) which discharge twice in one half voltage, respectively. Selected by the complex coupling of two subpatterns, the CDSSP can be formed and shows good stability. This investigation based on gas discharge theory together with nonlinear theory may provide a deeper understanding for the nonlinear characteristicsmore » and even the formation mechanism of patterns in DBD.« less

  19. Gas Phase Reactions of Ions Derived from Anionic Uranyl Formate and Uranyl Acetate Complexes

    NASA Astrophysics Data System (ADS)

    Perez, Evan; Hanley, Cassandra; Koehler, Stephen; Pestok, Jordan; Polonsky, Nevo; Van Stipdonk, Michael

    2016-12-01

    The speciation and reactivity of uranium are topics of sustained interest because of their importance to the development of nuclear fuel processing methods, and a more complete understanding of the factors that govern the mobility and fate of the element in the environment. Tandem mass spectrometry can be used to examine the intrinsic reactivity (i.e., free from influence of solvent and other condensed phase effects) of a wide range of metal ion complexes in a species-specific fashion. Here, electrospray ionization, collision-induced dissociation, and gas-phase ion-molecule reactions were used to create and characterize ions derived from precursors composed of uranyl cation (UVIO2 2+) coordinated by formate or acetate ligands. Anionic complexes containing UVIO2 2+ and formate ligands fragment by decarboxylation and elimination of CH2=O, ultimately to produce an oxo-hydride species [UVIO2(O)(H)]-. Cationic species ultimately dissociate to make [UVIO2(OH)]+. Anionic complexes containing acetate ligands exhibit an initial loss of acetyloxyl radical, CH3CO2•, with associated reduction of uranyl to UVO2 +. Subsequent CID steps cause elimination of CO2 and CH4, ultimately to produce [UVO2(O)]-. Loss of CH4 occurs by an intra-complex H+ transfer process that leaves UVO2 + coordinated by acetate and acetate enolate ligands. A subsequent dissociation step causes elimination of CH2=C=O to leave [UVO2(O)]-. Elimination of CH4 is also observed as a result of hydrolysis caused by ion-molecule reaction with H2O. The reactions of other anionic species with gas-phase H2O create hydroxyl products, presumably through the elimination of H2.

  20. High-frequency promoter firing links THO complex function to heavy chromatin formation.

    PubMed

    Mouaikel, John; Causse, Sébastien Z; Rougemaille, Mathieu; Daubenton-Carafa, Yves; Blugeon, Corinne; Lemoine, Sophie; Devaux, Frédéric; Darzacq, Xavier; Libri, Domenico

    2013-11-27

    The THO complex is involved in transcription, genome stability, and messenger ribonucleoprotein (mRNP) formation, but its precise molecular function remains enigmatic. Under heat shock conditions, THO mutants accumulate large protein-DNA complexes that alter the chromatin density of target genes (heavy chromatin), defining a specific biochemical facet of THO function and a powerful tool of analysis. Here, we show that heavy chromatin distribution is dictated by gene boundaries and that the gene promoter is necessary and sufficient to convey THO sensitivity in these conditions. Single-molecule fluorescence in situ hybridization measurements show that heavy chromatin formation correlates with an unusually high firing pace of the promoter with more than 20 transcription events per minute. Heavy chromatin formation closely follows the modulation of promoter firing and strongly correlates with polymerase occupancy genome wide. We propose that the THO complex is required for tuning the dynamic of gene-nuclear pore association and mRNP release to the same high pace of transcription initiation. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  1. Stabilization and activation of alpha-chymotrypsin in water-organic solvent systems by complex formation with oligoamines.

    PubMed

    Kudryashova, Elena V; Artemova, Tatiana M; Vinogradov, Alexei A; Gladilin, Alexander K; Mozhaev, Vadim V; Levashov, Andrey V

    2003-04-01

    Formation of enzyme-oligoamine complexes was suggested as an approach to obtain biocatalysts with enhanced resistance towards inactivation in water-organic media. Complex formation results in broadening (by 20-40% v/v ethanol) of the range of cosolvent concentrations where the enzyme retains its catalytic activity (stabilization effect). At moderate cosolvent concentrations (20-40% v/v) complex formation activates the enzyme (by 3-6 times). The magnitude of activation and stabilization effects increases with the number of possible electrostatic contacts between the protein surface and the molecules of oligoamines (OA). Circular dichroism spectra in the far-UV region show that complex formation stabilizes protein conformation and prevents aggregation in water-organic solvent mixtures. Two populations of the complexes with different thermodynamic stabilities were found in alpha-chymotrypsin (CT)-OA systems depending on the CT/OA ratio. The average dissociation constants and stoichiometries of both low- and high-affinity populations of the complexes were estimated. It appears that it is the low-affinity sites on the CT surface that are responsible for the activation effect.

  2. Model of a ternary complex between activated factor VII, tissue factor and factor IX.

    PubMed

    Chen, Shu-wen W; Pellequer, Jean-Luc; Schved, Jean-François; Giansily-Blaizot, Muriel

    2002-07-01

    Upon binding to tissue factor, FVIIa triggers coagulation by activating vitamin K-dependent zymogens, factor IX (FIX) and factor X (FX). To understand recognition mechanisms in the initiation step of the coagulation cascade, we present a three-dimensional model of the ternary complex between FVIIa:TF:FIX. This model was built using a full-space search algorithm in combination with computational graphics. With the known crystallographic complex FVIIa:TF kept fixed, the FIX docking was performed first with FIX Gla-EGF1 domains, followed by the FIX protease/EGF2 domains. Because the FIXa crystal structure lacks electron density for the Gla domain, we constructed a chimeric FIX molecule that contains the Gla-EGF1 domains of FVIIa and the EGF2-protease domains of FIXa. The FVIIa:TF:FIX complex has been extensively challenged against experimental data including site-directed mutagenesis, inhibitory peptide data, haemophilia B database mutations, inhibitor antibodies and a novel exosite binding inhibitor peptide. This FVIIa:TF:FIX complex provides a powerful tool to study the regulation of FVIIa production and presents new avenues for developing therapeutic inhibitory compounds of FVIIa:TF:substrate complex.

  3. A model complex of a possible intermediate in the mechanism of action of peptide deformylase: first example of an (N2S)zinc(II)-formate complex.

    PubMed

    Chang, S C; Sommer, R D; Rheingold, A L; Goldberg, D P

    2001-11-21

    The synthesis and crystallographic characterization of a new (N2S)zinc-alkyl complex and (N2S)zinc-formate complex is described; the bonding mode of the formate complex has implications for the mechanism of action of the enzyme peptide deformylase.

  4. Mechanistic investigation of the formation of H2 from HCOOH with a dinuclear Ru model complex for formate hydrogen lyase.

    PubMed

    Tokunaga, Taisuke; Yatabe, Takeshi; Matsumoto, Takahiro; Ando, Tatsuya; Yoon, Ki-Seok; Ogo, Seiji

    2017-01-01

    We report the mechanistic investigation of catalytic H 2 evolution from formic acid in water using a formate-bridged dinuclear Ru complex as a formate hydrogen lyase model. The mechanistic study is based on isotope-labeling experiments involving hydrogen isotope exchange reaction.

  5. Simulations of photochemical smog formation in complex urban areas

    NASA Astrophysics Data System (ADS)

    Muilwijk, C.; Schrijvers, P. J. C.; Wuerz, S.; Kenjereš, S.

    2016-12-01

    In the present study we numerically investigated the dispersion of photochemical reactive pollutants in complex urban areas by applying an integrated Computational Fluid Dynamics (CFD) and Computational Reaction Dynamics (CRD) approach. To model chemical reactions involved in smog generation, the Generic Reaction Set (GRS) approach is used. The GRS model was selected since it does not require detailed modeling of a large set of reactive components. Smog formation is modeled first in the case of an intensive traffic emission, subjected to low to moderate wind conditions in an idealized two-dimensional street canyon with a building aspect ratio (height/width) of one. It is found that Reactive Organic Components (ROC) play an important role in the chemistry of smog formation. In contrast to the NOx/O3 photochemical steady state model that predicts a depletion of the (ground level) ozone, the GRS model predicts generation of ozone. Secondly, the effect of direct sunlight and shadow within the street canyon on the chemical reaction dynamics is investigated for three characteristic solar angles (morning, midday and afternoon). Large differences of up to one order of magnitude are found in the ozone production for different solar angles. As a proof of concept for real urban areas, the integrated CFD/CRD approach is applied for a real scale (1 × 1 km2) complex urban area (a district of the city of Rotterdam, The Netherlands) with high traffic emissions. The predicted pollutant concentration levels give realistic values that correspond to moderate to heavy smog. It is concluded that the integrated CFD/CRD method with the GRS model of chemical reactions is both accurate and numerically robust, and can be used for modeling of smog formation in complex urban areas.

  6. Control of cell fate by the formation of an architecturally complex bacterial community.

    PubMed

    Vlamakis, Hera; Aguilar, Claudio; Losick, Richard; Kolter, Roberto

    2008-04-01

    Bacteria form architecturally complex communities known as biofilms in which cells are held together by an extracellular matrix. Biofilms harbor multiple cell types, and it has been proposed that within biofilms individual cells follow different developmental pathways, resulting in heterogeneous populations. Here we demonstrate cellular differentiation within biofilms of the spore-forming bacterium Bacillus subtilis, and present evidence that formation of the biofilm governs differentiation. We show that motile, matrix-producing, and sporulating cells localize to distinct regions within the biofilm, and that the localization and percentage of each cell type is dynamic throughout development of the community. Importantly, mutants that do not produce extracellular matrix form unstructured biofilms that are deficient in sporulation. We propose that sporulation is a culminating feature of biofilm formation, and that spore formation is coupled to the formation of an architecturally complex community of cells.

  7. Control of cell fate by the formation of an architecturally complex bacterial community

    PubMed Central

    Vlamakis, Hera; Aguilar, Claudio; Losick, Richard; Kolter, Roberto

    2008-01-01

    Bacteria form architecturally complex communities known as biofilms in which cells are held together by an extracellular matrix. Biofilms harbor multiple cell types, and it has been proposed that within biofilms individual cells follow different developmental pathways, resulting in heterogeneous populations. Here we demonstrate cellular differentiation within biofilms of the spore-forming bacterium Bacillus subtilis, and present evidence that formation of the biofilm governs differentiation. We show that motile, matrix-producing, and sporulating cells localize to distinct regions within the biofilm, and that the localization and percentage of each cell type is dynamic throughout development of the community. Importantly, mutants that do not produce extracellular matrix form unstructured biofilms that are deficient in sporulation. We propose that sporulation is a culminating feature of biofilm formation, and that spore formation is coupled to the formation of an architecturally complex community of cells. PMID:18381896

  8. The plant cell cycle: Pre-Replication complex formation and controls

    PubMed Central

    Brasil, Juliana Nogueira; Costa, Carinne N. Monteiro; Cabral, Luiz Mors; Ferreira, Paulo C. G.; Hemerly, Adriana S.

    2017-01-01

    Abstract The multiplication of cells in all living organisms requires a tight regulation of DNA replication. Several mechanisms take place to ensure that the DNA is replicated faithfully and just once per cell cycle in order to originate through mitoses two new daughter cells that contain exactly the same information from the previous one. A key control mechanism that occurs before cells enter S phase is the formation of a pre-replication complex (pre-RC) that is assembled at replication origins by the sequential association of the origin recognition complex, followed by Cdt1, Cdc6 and finally MCMs, licensing DNA to start replication. The identification of pre-RC members in all animal and plant species shows that this complex is conserved in eukaryotes and, more importantly, the differences between kingdoms might reflect their divergence in strategies on cell cycle regulation, as it must be integrated and adapted to the niche, ecosystem, and the organism peculiarities. Here, we provide an overview of the knowledge generated so far on the formation and the developmental controls of the pre-RC mechanism in plants, analyzing some particular aspects in comparison to other eukaryotes. PMID:28304073

  9. Terabit bandwidth-adaptive transmission using low-complexity format-transparent digital signal processing.

    PubMed

    Zhuge, Qunbi; Morsy-Osman, Mohamed; Chagnon, Mathieu; Xu, Xian; Qiu, Meng; Plant, David V

    2014-02-10

    In this paper, we propose a low-complexity format-transparent digital signal processing (DSP) scheme for next generation flexible and energy-efficient transceiver. It employs QPSK symbols as the training and pilot symbols for the initialization and tracking stage of the receiver-side DSP, respectively, for various modulation formats. The performance is numerically and experimentally evaluated in a dual polarization (DP) 11 Gbaud 64QAM system. Employing the proposed DSP scheme, we conduct a system-level study of Tb/s bandwidth-adaptive superchannel transmissions with flexible modulation formats including QPSK, 8QAM and 16QAM. The spectrum bandwidth allocation is realized in the digital domain instead of turning on/off sub-channels, which improves the performance of higher order QAM. Various transmission distances ranging from 240 km to 6240 km are demonstrated with a colorless detection for hardware complexity reduction.

  10. [Studies by means of 1H NMR spectroscopy of complex formation of aromatic biologically active compounds with antibiotic topotecan].

    PubMed

    Mosunov, A A; Kostiukov, V V; Evstigneev, M P

    2012-01-01

    The analysis of heteroassociation of antibiotic topotecan (TPT) with aromatic biologically active compounds (BAC): caffeine, mutagens ethidium bromide and proflavine, antibiotic daunomycin, vitamins flavin-mononucleotide and nicotinamide, has been carried out in the work using 1H NMR spectroscopy data. The equilibrium constants of heteroassociation and induced chemical shifts of the protons have been obtained in the complexes with BAC. It is found that the complex formation TPT-BAC has the nature of stacking of the chromophores, additionally stabilized in the case of proflavine by intermolecular hydrogen bond. Calculation of the basic components of the Gibbs free energy of the complexation reactions is carried out, and the factors which stabilize and destabilize the heterocomplexes of molecules are revealed.

  11. Formation and Recondensation of Complex Organic Molecules During Protostellar Luminosity Outbursts

    NASA Technical Reports Server (NTRS)

    Taquet, Vianney; Wirstrom, Eva S.; Charnley, Steven B.

    2016-01-01

    During the formation of stars, the accretion of surrounding material toward the central object is thought to undergo strong luminosity outbursts followed by long periods of relative quiescence, even at the early stages of star formation when the protostar is still embedded in a large envelope. We investigated the gas-phase formation and recondensation of the complex organic molecules (COMs) di-methyl ether and methyl formate, induced by sudden ice evaporation processes occurring during luminosity outbursts of different amplitudes in protostellar envelopes. For this purpose, we updated a gas-phase chemical network forming COMs in which ammonia plays a key role. The model calculations presented here demonstrate that ion-molecule reactions alone could account for the observed presence of di-methyl ether and methyl formate in a large fraction of protostellar cores without recourse to grain-surface chemistry, although they depend on uncertain ice abundances and gas-phase reaction branching ratios. In spite of the short outburst timescales of about 100 years, abundance ratios of the considered species higher than 10% with respect to methanol are predicted during outbursts due to their low binding energies relative to water and methanol which delay their recondensation during cooling. Although the current luminosity of most embedded protostars would be too low to produce complex organics in the hot-core regions that are observable with current sub-millimetric interferometers, previous luminosity outburst events would induce the formation of COMs in extended regions of protostellar envelopes with sizes increasing by up to one order of magnitude.

  12. Formation and Recondensation of Complex Organic Molecules during Protostellar Luminosity Outbursts

    NASA Astrophysics Data System (ADS)

    Taquet, Vianney; Wirström, Eva S.; Charnley, Steven B.

    2016-04-01

    During the formation of stars, the accretion of surrounding material toward the central object is thought to undergo strong luminosity outbursts followed by long periods of relative quiescence, even at the early stages of star formation when the protostar is still embedded in a large envelope. We investigated the gas-phase formation and recondensation of the complex organic molecules (COMs) di-methyl ether and methyl formate, induced by sudden ice evaporation processes occurring during luminosity outbursts of different amplitudes in protostellar envelopes. For this purpose, we updated a gas-phase chemical network forming COMs in which ammonia plays a key role. The model calculations presented here demonstrate that ion-molecule reactions alone could account for the observed presence of di-methyl ether and methyl formate in a large fraction of protostellar cores without recourse to grain-surface chemistry, although they depend on uncertain ice abundances and gas-phase reaction branching ratios. In spite of the short outburst timescales of about 100 years, abundance ratios of the considered species higher than 10% with respect to methanol are predicted during outbursts due to their low binding energies relative to water and methanol which delay their recondensation during cooling. Although the current luminosity of most embedded protostars would be too low to produce complex organics in the hot-core regions that are observable with current sub-millimetric interferometers, previous luminosity outburst events would induce the formation of COMs in extended regions of protostellar envelopes with sizes increasing by up to one order of magnitude.

  13. FORMATION AND RECONDENSATION OF COMPLEX ORGANIC MOLECULES DURING PROTOSTELLAR LUMINOSITY OUTBURSTS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Taquet, Vianney; Wirström, Eva S.; Charnley, Steven B.

    2016-04-10

    During the formation of stars, the accretion of surrounding material toward the central object is thought to undergo strong luminosity outbursts followed by long periods of relative quiescence, even at the early stages of star formation when the protostar is still embedded in a large envelope. We investigated the gas-phase formation and recondensation of the complex organic molecules (COMs) di-methyl ether and methyl formate, induced by sudden ice evaporation processes occurring during luminosity outbursts of different amplitudes in protostellar envelopes. For this purpose, we updated a gas-phase chemical network forming COMs in which ammonia plays a key role. The modelmore » calculations presented here demonstrate that ion–molecule reactions alone could account for the observed presence of di-methyl ether and methyl formate in a large fraction of protostellar cores without recourse to grain-surface chemistry, although they depend on uncertain ice abundances and gas-phase reaction branching ratios. In spite of the short outburst timescales of about 100 years, abundance ratios of the considered species higher than 10% with respect to methanol are predicted during outbursts due to their low binding energies relative to water and methanol which delay their recondensation during cooling. Although the current luminosity of most embedded protostars would be too low to produce complex organics in the hot-core regions that are observable with current sub-millimetric interferometers, previous luminosity outburst events would induce the formation of COMs in extended regions of protostellar envelopes with sizes increasing by up to one order of magnitude.« less

  14. Subcutaneous administration of insulin-like growth factor (IGF)-II/IGF binding protein-2 complex stimulates bone formation and prevents loss of bone mineral density in a rat model of disuse osteoporosis

    NASA Technical Reports Server (NTRS)

    Conover, Cheryl A.; Johnstone, Edward W.; Turner, Russell T.; Evans, Glenda L.; John Ballard, F. John; Doran, Patrick M.; Khosla, Sundeep

    2002-01-01

    Elevated serum levels of insulin-like growth factor binding protein-2 (IGFBP-2) and a precursor form of IGF-II are associated with marked increases in bone formation and skeletal mass in patients with hepatitis C-associated osteosclerosis. In vitro studies indicate that IGF-II in complex with IGFBP-2 has high affinity for bone matrix and is able to stimulate osteoblast proliferation. The purpose of this study was to determine the ability of the IGF-II/IGFBP-2 complex to increase bone mass in vivo. Osteopenia of the femur was induced by unilateral sciatic neurectomy in rats. At the time of surgery, 14-day osmotic minipumps containing vehicle or 2 microg IGF-II+9 microg IGFBP-2/100g body weight/day were implanted subcutaneously in the neck. Bone mineral density (BMD) measurements were taken the day of surgery and 14 days later using a PIXImus small animal densitometer. Neurectomy of the right hindlimb resulted in a 9% decrease in right femur BMD (P<0.05 vs. baseline). This loss in BMD was completely prevented by treatment with IGF-II/IGFBP-2. On the control limb, there was no loss of BMD over the 14 days and IGF-II/IGFBP-2 treatment resulted in a 9% increase in left femur BMD (P<0.05). Bone histomorphometry indicated increases in endocortical and cancellous bone formation rates and in trabecular thickness. These results demonstrate that short-term administration of the IGF-II/IGFBP-2 complex can prevent loss of BMD associated with disuse osteoporosis and stimulate bone formation in adult rats. Furthermore, they provide proof of concept for a novel anabolic approach to increasing bone mass in humans with osteoporosis.

  15. Improving the Factor Structure of Psychological Scales: The Expanded Format as an Alternative to the Likert Scale Format

    ERIC Educational Resources Information Center

    Zhang, Xijuan; Savalei, Victoria

    2016-01-01

    Many psychological scales written in the Likert format include reverse worded (RW) items in order to control acquiescence bias. However, studies have shown that RW items often contaminate the factor structure of the scale by creating one or more method factors. The present study examines an alternative scale format, called the Expanded format,…

  16. Gas Phase Reactions of Ions Derived from Anionic Uranyl Formate and Uranyl Acetate Complexes.

    PubMed

    Perez, Evan; Hanley, Cassandra; Koehler, Stephen; Pestok, Jordan; Polonsky, Nevo; Van Stipdonk, Michael

    2016-12-01

    The speciation and reactivity of uranium are topics of sustained interest because of their importance to the development of nuclear fuel processing methods, and a more complete understanding of the factors that govern the mobility and fate of the element in the environment. Tandem mass spectrometry can be used to examine the intrinsic reactivity (i.e., free from influence of solvent and other condensed phase effects) of a wide range of metal ion complexes in a species-specific fashion. Here, electrospray ionization, collision-induced dissociation, and gas-phase ion-molecule reactions were used to create and characterize ions derived from precursors composed of uranyl cation (U VI O 2 2+ ) coordinated by formate or acetate ligands. Anionic complexes containing U VI O 2 2+ and formate ligands fragment by decarboxylation and elimination of CH 2 =O, ultimately to produce an oxo-hydride species [U VI O 2 (O)(H)] - . Cationic species ultimately dissociate to make [U VI O 2 (OH)] + . Anionic complexes containing acetate ligands exhibit an initial loss of acetyloxyl radical, CH 3 CO 2 •, with associated reduction of uranyl to U V O 2 + . Subsequent CID steps cause elimination of CO 2 and CH 4 , ultimately to produce [U V O 2 (O)] - . Loss of CH 4 occurs by an intra-complex H + transfer process that leaves U V O 2 + coordinated by acetate and acetate enolate ligands. A subsequent dissociation step causes elimination of CH 2 =C=O to leave [U V O 2 (O)] - . Elimination of CH 4 is also observed as a result of hydrolysis caused by ion-molecule reaction with H 2 O. The reactions of other anionic species with gas-phase H 2 O create hydroxyl products, presumably through the elimination of H 2 . Graphical Abstract ᅟ.

  17. Molecular determinants of orexin receptor-arrestin-ubiquitin complex formation.

    PubMed

    Jaeger, Werner C; Seeber, Ruth M; Eidne, Karin A; Pfleger, Kevin D G

    2014-01-01

    The orexin system regulates a multitude of key physiological processes, particularly involving maintenance of metabolic homeostasis. Consequently, there is considerable potential for pharmaceutical development for the treatment of disorders from narcolepsy to metabolic syndrome. It acts through the hormonal activity of two endogenous peptides, orexin A binding to orexin receptors 1 and 2 (OX₁ and OX₂) with similar affinity, and orexin B binding to OX₂ with higher affinity than OX₁ receptors. We have previously revealed data differentiating orexin receptor subtypes with respect to their relative stability in forming orexin receptor-arrestin-ubiquitin complexes measured by BRET. Recycling and cellular signalling distinctions were also observed. Here, we have investigated, using BRET, the molecular determinants involved in providing OX₂ receptors with greater β-arrestin-ubiquitin complex stability. The contribution of the C-terminal tail of the OX receptors was investigated by bulk substitution and site-specific mutagenesis using BRET and inositol phosphate assays. Replacement of the OX₁ receptor C-terminus with that of the OX₂ receptor did not result in the expected gain of function, indicating a role for intracellular domain configuration in addition to primary structure. Furthermore, two out of the three putative serine/threonine clusters in the C-terminus were found to be involved in OX₂ receptor-β-arrestin-ubiquitin complex formation. This study provides fundamental insights into the molecular elements that influence receptor-arrestin-ubiquitin complex formation. Understanding how and why the orexin receptors can be functionally differentiated brings us closer to exploiting these receptors as drug targets. © 2013 The Authors. British Journal of Pharmacology published by John Wiley &. Sons Ltd on behalf of The British Pharmacological Society.

  18. Analysis of the Enhanced Stability of R(+)-Alpha Lipoic Acid by the Complex Formation with Cyclodextrins

    PubMed Central

    Ikuta, Naoko; Sugiyama, Hironori; Shimosegawa, Hiroshi; Nakane, Rie; Ishida, Yoshiyuki; Uekaji, Yukiko; Nakata, Daisuke; Pallauf, Kathrin; Rimbach, Gerald; Terao, Keiji; Matsugo, Seiichi

    2013-01-01

    R(+)-alpha lipoic acid (RALA) is one of the cofactors for mitochondrial enzymes and, therefore, plays a central role in energy metabolism. RALA is unstable when exposed to low pH or heat, and therefore, it is difficult to use enantiopure RALA as a pharma- and nutra-ceutical. In this study, we have aimed to stabilize RALA through complex formation with cyclodextrins (CDs). α-CD, β-CD and γ-CD were used for the formation of these RALA-CD complexes. We confirmed the complex formation using differential scanning calorimetry and showed by using HPLC analysis that complexed RALA is more stable than free RALA when subjected to humidity and high temperature or acidic pH conditions. Scanning electron microscopy studies showed that the particle size and shape differed depending on the cyclodextrin used for complexation. Further, the complexes of CD and RALA showed a different particle size distribution pattern compared with that of CD itself or that of the physical mixture of RALA and CD. PMID:23434662

  19. Vancomycin: ligand recognition, dimerization and super-complex formation.

    PubMed

    Jia, ZhiGuang; O'Mara, Megan L; Zuegg, Johannes; Cooper, Matthew A; Mark, Alan E

    2013-03-01

    The antibiotic vancomycin targets lipid II, blocking cell wall synthesis in Gram-positive bacteria. Despite extensive study, questions remain regarding how it recognizes its primary ligand and what is the most biologically relevant form of vancomycin. In this study, molecular dynamics simulation techniques have been used to examine the process of ligand binding and dimerization of vancomycin. Starting from one or more vancomycin monomers in solution, together with different peptide ligands derived from lipid II, the simulations predict the structures of the ligated monomeric and dimeric complexes to within 0.1 nm rmsd of the structures determined experimentally. The simulations reproduce the conformation transitions observed by NMR and suggest that proposed differences between the crystal structure and the solution structure are an artifact of the way the NMR data has been interpreted in terms of a structural model. The spontaneous formation of both back-to-back and face-to-face dimers was observed in the simulations. This has allowed a detailed analysis of the origin of the cooperatively between ligand binding and dimerization and suggests that the formation of face-to-face dimers could be functionally significant. The work also highlights the possible role of structural water in stabilizing the vancomycin ligand complex and its role in the manifestation of vancomycin resistance. © 2013 The Authors Journal compilation © 2013 FEBS.

  20. Asymmetrical Macromolecular Complex Formation of Lysophosphatidic Acid Receptor 2 (LPA2) Mediates Gradient Sensing in Fibroblasts*

    PubMed Central

    Ren, Aixia; Moon, Changsuk; Zhang, Weiqiang; Sinha, Chandrima; Yarlagadda, Sunitha; Arora, Kavisha; Wang, Xusheng; Yue, Junming; Parthasarathi, Kaushik; Heil-Chapdelaine, Rick; Tigyi, Gabor; Naren, Anjaparavanda P.

    2014-01-01

    Chemotactic migration of fibroblasts toward growth factors relies on their capacity to sense minute extracellular gradients and respond to spatially confined receptor-mediated signals. Currently, mechanisms underlying the gradient sensing of fibroblasts remain poorly understood. Using single-particle tracking methodology, we determined that a lysophosphatidic acid (LPA) gradient induces a spatiotemporally restricted decrease in the mobility of LPA receptor 2 (LPA2) on chemotactic fibroblasts. The onset of decreased LPA2 mobility correlates to the spatial recruitment and coupling to LPA2-interacting proteins that anchor the complex to the cytoskeleton. These localized PDZ motif-mediated macromolecular complexes of LPA2 trigger a Ca2+ puff gradient that governs gradient sensing and directional migration in response to LPA. Disruption of the PDZ motif-mediated assembly of the macromolecular complex of LPA2 disorganizes the gradient of Ca2+ puffs, disrupts gradient sensing, and reduces the directional migration of fibroblasts toward LPA. Our findings illustrate that the asymmetric macromolecular complex formation of chemoattractant receptors mediates gradient sensing and provides a new mechanistic basis for models to describe gradient sensing of fibroblasts. PMID:25542932

  1. Repression of PDGF-R-α after cellular injury involves TNF-α, formation of a c-Fos-YY1 complex, and negative regulation by HDAC.

    PubMed

    Zhang, Ning; Chan, Cecilia W S; Sanchez-Guerrero, Estella; Khachigian, Levon M

    2012-06-01

    Wound healing is a complex dynamic process involving a variety of cell types, including fibroblasts that express and respond to cytokines and growth factors in the local microenvironment. The mechanisms controlling gene expression after injury at a transcriptional level are poorly understood. Here we show that decreased expression of a key receptor, PDGF-receptor (R)-α, after fibroblast injury is due to the release and paracrine activity of TNF-α. TNF-α inhibits PDGF-R-α expression and this involves formation of a c-Fos-Yin Yang 1 (YY1) complex and histone deacetylase (HDAC) activity. c-Fos, induced by TNF-α, negatively regulates PDGF-R-α transcription. Small interfering RNA (siRNA) targeting c-Fos or the zinc finger transcription factor YY1 inhibits TNF-α suppression of PDGF-R-α expression. Coimmunoprecipitation studies show that TNF-α stimulates the formation of a complex between c-Fos with YY1. Furthermore, chromatin immunoprecipitation (ChIP) analysis reveals the enrichment of c-Fos, YY1, and HDAC-1 at the PDGF-R-α promoter in cells exposed to TNF-α. With suberoylanilide hydroxamic acid (SAHA) and HDAC-1 siRNA, we demonstrate that HDAC mediates TNF-α repression of PDGF-R-α. These findings demonstrate that transcriptional repression of PDGF-R-α after fibroblast injury involves paracrine activity of endogenous TNF-α, the formation of a c-Fos-YY1 complex, and negative regulatory activity by HDAC.

  2. Interference-mediated synaptonemal complex formation with embedded crossover designation

    PubMed Central

    Zhang, Liangran; Espagne, Eric; de Muyt, Arnaud; Zickler, Denise; Kleckner, Nancy E.

    2014-01-01

    Biological systems exhibit complex patterns at length scales ranging from the molecular to the organismic. Along chromosomes, events often occur stochastically at different positions in different nuclei but nonetheless tend to be relatively evenly spaced. Examples include replication origin firings, formation of chromatin loops along chromosome axes and, during meiosis, localization of crossover recombination sites (“crossover interference”). We present evidence in the fungus Sordaria macrospora that crossover interference is part of a broader pattern that includes synaptonemal complex (SC) nucleation. This pattern comprises relatively evenly spaced SC nucleation sites, among which a subset are crossover sites that show a classical interference distribution. This pattern ensures that SC forms regularly along the entire length of the chromosome as required for the maintenance of homolog pairing while concomitantly having crossover interactions locally embedded within the SC structure as required for both DNA recombination and structural events of chiasma formation. This pattern can be explained by a threshold-based designation and spreading interference process. This model can be generalized to give diverse types of related and/or partially overlapping patterns, in two or more dimensions, for any type of object. PMID:25380597

  3. Architecture and nucleic acids recognition mechanism of the THO complex, an mRNP assembly factor

    PubMed Central

    Peña, Álvaro; Gewartowski, Kamil; Mroczek, Seweryn; Cuéllar, Jorge; Szykowska, Aleksandra; Prokop, Andrzej; Czarnocki-Cieciura, Mariusz; Piwowarski, Jan; Tous, Cristina; Aguilera, Andrés; Carrascosa, José L; Valpuesta, José María; Dziembowski, Andrzej

    2012-01-01

    The THO complex is a key factor in co-transcriptional formation of export-competent messenger ribonucleoprotein particles, yet its structure and mechanism of chromatin recruitment remain unknown. In yeast, this complex has been described as a heterotetramer (Tho2, Hpr1, Mft1, and Thp2) that interacts with Tex1 and mRNA export factors Sub2 and Yra1 to form the TRanscription EXport (TREX) complex. In this study, we purified yeast THO and found Tex1 to be part of its core. We determined the three-dimensional structures of five-subunit THO complex by electron microscopy and located the positions of Tex1, Hpr1, and Tho2 C-terminus using various labelling techniques. In the case of Tex1, a β-propeller protein, we have generated an atomic model which docks into the corresponding part of the THO complex envelope. Furthermore, we show that THO directly interacts with nucleic acids through the unfolded C-terminal region of Tho2, whose removal reduces THO recruitment to active chromatin leading to mRNA biogenesis defects. In summary, this study describes the THO architecture, the structural basis for its chromatin targeting, and highlights the importance of unfolded regions of eukaryotic proteins. PMID:22314234

  4. [Characteristics of marketing complex formation in rendering of sanatorium resort services].

    PubMed

    Kemalov, R F

    2006-01-01

    Basic positions in sanatorium resort marketing and its evolution with description of its main components are considered. Marketing research management in sanatorium resort institutions, marketing theory, analysis of services market, characteristics of marketing complex formation are presented.

  5. Distinct contributions of complement factors to platelet activation and fibrin formation in venous thrombus development

    PubMed Central

    Jäckel, Sven; Saffarzadeh, Mona; Langer, Florian

    2017-01-01

    Expanding evidence indicates multiple interactions between the hemostatic system and innate immunity, and the coagulation and complement cascades. Here we show in a tissue factor (TF)–dependent model of flow restriction-induced venous thrombosis that complement factors make distinct contributions to platelet activation and fibrin deposition. Complement factor 3 (C3) deficiency causes prolonged bleeding, reduced thrombus incidence, thrombus size, fibrin and platelet deposition in the ligated inferior vena cava, and diminished platelet activation in vitro. Initial fibrin deposition at the vessel wall over 6 hours in this model was dependent on protein disulfide isomerase (PDI) and TF expression by myeloid cells, but did not require neutrophil extracellular trap formation involving peptidyl arginine deiminase 4. In contrast to C3−/− mice, C5-deficient mice had no apparent defect in platelet activation in vitro, and vessel wall platelet deposition and initial hemostasis in vivo. However, fibrin formation, the exposure of negatively charged phosphatidylserine (PS) on adherent leukocytes, and clot burden after 48 hours were significantly reduced in C5−/− mice compared with wild-type controls. These results delineate that C3 plays specific roles in platelet activation independent of formation of the terminal complement complex and provide in vivo evidence for contributions of complement-dependent membrane perturbations to prothrombotic TF activation on myeloid cells. PMID:28223279

  6. Star-formation complexes in the `galaxy-sized' supergiant shell of the galaxy Holmberg I

    NASA Astrophysics Data System (ADS)

    Egorov, Oleg V.; Lozinskaya, Tatiana A.; Moiseev, Alexei V.; Smirnov-Pinchukov, Grigory V.

    2018-05-01

    We present the results of observations of the galaxy Holmberg I carried out at the Russian 6-m telescope in the narrow-band imaging, long-slit spectroscopy, and scanning Fabry-Perot interferometer modes. A detailed analysis of gas kinematics, ionization conditions, and metallicity of star-forming regions in the galaxy is presented. The aim of the paper is to analyse the propagation of star formation in the galaxy and to understand the role of the ongoing star formation in the evolution of the central `galaxy-sized' supergiant H I shell (SGS), where all regions of star formation are observed. We show that star formation in the galaxy occurs in large unified complexes rather than in individual giant H II regions. Evidence of the triggered star formation is observed both on scales of individual complexes and of the whole galaxy. We identified two supernova-remnant candidates and one late-type WN star and analysed their spectrum and surrounding-gas kinematics. We provide arguments indicating that the SGS in Holmberg I is destructing by the influence of star formation occurring on its rims.

  7. Activated Prothrombin Complex Concentrate Versus 4-Factor Prothrombin Complex Concentrate for Vitamin K-Antagonist Reversal.

    PubMed

    Rowe, A Shaun; Dietrich, Scott K; Phillips, John W; Foster, Kaci E; Canter, Joshua R

    2018-06-01

    To compare the international normalized ratio normalization efficacy of activated prothrombin complex concentrates and 4-factor prothrombin complex concentrates and to evaluate the thrombotic complications in patients treated with these products for warfarin-associated hemorrhage. Retrospective, Multicenter Cohort. Large, Community, Teaching Hospital. Patients greater than 18 years old and received either activated prothrombin complex concentrate or 4-factor prothrombin complex concentrate for the treatment of warfarin-associated hemorrhage. We excluded those patients who received either agent for an indication other than warfarin-associated hemorrhage, pregnant, had a baseline international normalized ratio of less than 2, received a massive transfusion as defined by hospital protocol, received plasma for treatment of warfarin-associated hemorrhage, or were treated for an acute warfarin ingestion. Patients in the activated prothrombin complex concentrate group (enrolled from one hospital) with an international normalized ratio of less than 5 received 500 IU and those with an international normalized ratio greater than 5 received 1,000 IU. Patients in the 4-factor prothrombin complex concentrate (enrolled from a separate hospital) group received the Food and Drug Administration approved dosing algorithm. A total of 158 patients were included in the final analysis (activated prothrombin complex concentrate = 118; 4-factor prothrombin complex concentrate = 40). Those in the 4-factor prothrombin complex concentrate group had a higher pretreatment international normalized ratio (2.7 ± 1.8 vs 3.5 ± 2.9; p = 0.0164). However, the posttreatment international normalized ratio was similar between the groups. In addition, even when controlling for differences in the pretreatment international normalized ratio, there was no difference in the ability to achieve a posttreatment international normalized ratio of less than 1.4 (odds ratio, 0.753 [95% CI, 0.637-0.890]; p

  8. Effect of environmental factors on the complexation of iron and humic acid.

    PubMed

    Fang, Kai; Yuan, Dongxing; Zhang, Lei; Feng, Lifeng; Chen, Yaojin; Wang, Yuzhou

    2015-01-01

    A method of size exclusion chromatography coupled with ultraviolet spectrophotometry and off-line graphite furnace atomic absorption spectrometry was developed to assess the complexation properties of iron (Fe) and humic acid (HA) in a water environment. The factors affecting the complexation of Fe and HA, such as ionic strength, pH, temperature and UV radiation, were investigated. The Fe-HA complex residence time was also studied. Experimental results showed that pH could influence the deprotonation of HA and hydrolysis of Fe, and thus affected the complexation of Fe and HA. The complexation was greatly disrupted by the presence of NaCl. Temperature had some influence on the complexation. The yield of Fe-HA complexes showed a small decrease at high levels of UV radiation, but the effect of UV radiation on Fe-HA complex formation at natural levels could be neglected. It took about 10 hr for the complexation to reach equilibrium, and the Fe-HA complex residence time was about 20 hr. Complexation of Fe and HA reached a maximum level under the conditions of pH 6, very low ionic strength, in the dark and at a water temperature of about 25°C, for 10 hr. It was suggested that the Fe-HA complex could form mainly in freshwater bodies and reach high levels in the warm season with mild sunlight radiation. With changing environmental parameters, such as at lower temperature in winter or higher pH and ionic strength in an estuary, the concentration of the Fe-HA complex would decrease. Copyright © 2014. Published by Elsevier B.V.

  9. Mechanisms Underlying the Formation of Complexes between Maize Starch and Lipids.

    PubMed

    Chao, Chen; Yu, Jinglin; Wang, Shuo; Copeland, Les; Wang, Shujun

    2018-01-10

    This study aimed to reveal the mechanism of formation of complexes between native maize starch (NMS) and different types of lipids, namely palmitic acid (PA), monopalmitate glycerol (MPG), dipalmitate glycerol (DPG), and tripalmitate glycerol (TPG). The complexing index followed the order of MPG (96.3%) > PA (41.8%) > TPG (8.3%) > DPG (1.1%), indicating that MPG formed more complexes with NMS than PA, and that few complexes were formed between NMS and DPG and TPG. The NMS-PA complex presented higher thermal transition temperatures and lower enthalpy change than the NMS-MPG complex, indicating that although MPG formed more starch complexes, they had less stable crystalline structures than the complex between NMS and PA. X-ray diffraction (XRD) and Raman spectroscopy showed that both MPG and PA formed V-type crystalline structures with NMS, and confirmed that no complexes were formed between NMS and DPG and TPG. We conclude that the monoglyceride formed more starch-lipid complex with maize starch than PA, but that the monoglyceride complex had a less stable structure than that formed with PA. The di- and triglycerides did not form complexes with maize starch.

  10. Formation of a repressive complex in the mammalian circadian clock is mediated by the secondary pocket of CRY1

    DOE PAGES

    Michael, Alicia K.; Fribourgh, Jennifer L.; Chelliah, Yogarany; ...

    2017-01-31

    The basic helix-loop-helix PAS domain (bHLH-PAS) transcription factor CLOCK:BMAL1 (brain and muscle Arnt-like protein 1) sits at the core of the mammalian circadian transcription/translation feedback loop. Precise control of CLOCK:BMAL1 activity by coactivators and repressors establishes the ~24-h periodicity of gene expression. Formation of a repressive complex, defined by the core clock proteins cryptochrome 1 (CRY1):CLOCK:BMAL1, plays an important role controlling the switch from repression to activation each day. Here in this paper, we show that CRY1 binds directly to the PAS domain core of CLOCK: BMAL1, driven primarily by interaction with the CLOCK PAS-B domain. Integrative modeling and solutionmore » X-ray scattering studies unambiguously position a key loop of the CLOCK PAS-B domain in the secondary pocket of CRY1, analogous to the antenna chromophore-binding pocket of photolyase. CRY1 docks onto the transcription factor alongside the PAS domains, extending above the DNA-binding bHLH domain. Single point mutations at the interface on either CRY1 or CLOCK disrupt formation of the ternary complex, highlighting the importance of this interface for direct regulation of CLOCK:BMAL1 activity by CRY1.« less

  11. Nucleation promoting factors regulate the expression and localization of Arp2/3 complex during meiosis of mouse oocytes.

    PubMed

    Liu, Jun; Wang, Qiao-Chu; Wang, Fei; Duan, Xing; Dai, Xiao-Xin; Wang, Teng; Liu, Hong-Lin; Cui, Xiang-Shun; Kim, Nam-Hyung; Sun, Shao-Chen

    2012-01-01

    The actin nucleation factor Arp2/3 complex is a main regulator of actin assembly and is involved in multiple processes like cell migration and adhesion, endocytosis, and the establishment of cell polarity in mitosis. Our previous work showed that the Arp2/3 complex was involved in the actin-mediated mammalian oocyte asymmetric division. However, the regulatory mechanisms and signaling pathway of Arp2/3 complex in meiosis is still unclear. In the present work, we identified that the nucleation promoting factors (NPFs) JMY and WAVE2 were necessary for the expression and localization of Arp2/3 complex in mouse oocytes. RNAi of both caused the degradation of actin cap intensity, indicating the roles of NPFs in the formation of actin cap. Moreover, JMY and WAVE2 RNAi decreased the expression of ARP2, a key component of Arp2/3 complex. However, knock down of Arp2/3 complex by Arpc2 and Arpc3 siRNA microinjection did not affect the expression and localization of JMY and WAVE2. Our results indicate that the NPFs, JMY and WAVE2, are upstream regulators of Arp2/3 complex in mammalian oocyte asymmetric division.

  12. Nucleation Promoting Factors Regulate the Expression and Localization of Arp2/3 Complex during Meiosis of Mouse Oocytes

    PubMed Central

    Liu, Jun; Wang, Qiao-Chu; Wang, Fei; Duan, Xing; Dai, Xiao-Xin; Wang, Teng; Liu, Hong-Lin; Cui, Xiang-Shun; Kim, Nam-Hyung; Sun, Shao-Chen

    2012-01-01

    The actin nucleation factor Arp2/3 complex is a main regulator of actin assembly and is involved in multiple processes like cell migration and adhesion, endocytosis, and the establishment of cell polarity in mitosis. Our previous work showed that the Arp2/3 complex was involved in the actin-mediated mammalian oocyte asymmetric division. However, the regulatory mechanisms and signaling pathway of Arp2/3 complex in meiosis is still unclear. In the present work, we identified that the nucleation promoting factors (NPFs) JMY and WAVE2 were necessary for the expression and localization of Arp2/3 complex in mouse oocytes. RNAi of both caused the degradation of actin cap intensity, indicating the roles of NPFs in the formation of actin cap. Moreover, JMY and WAVE2 RNAi decreased the expression of ARP2, a key component of Arp2/3 complex. However, knock down of Arp2/3 complex by Arpc2 and Arpc3 siRNA microinjection did not affect the expression and localization of JMY and WAVE2. Our results indicate that the NPFs, JMY and WAVE2, are upstream regulators of Arp2/3 complex in mammalian oocyte asymmetric division. PMID:23272233

  13. Elevated plasma factor VIII enhances venous thrombus formation in rabbits: contribution of factor XI, von Willebrand factor and tissue factor.

    PubMed

    Sugita, Chihiro; Yamashita, Atsushi; Matsuura, Yunosuke; Iwakiri, Takashi; Okuyama, Nozomi; Matsuda, Shuntaro; Matsumoto, Tomoko; Inoue, Osamu; Harada, Aya; Kitazawa, Takehisa; Hattori, Kunihiro; Shima, Midori; Asada, Yujiro

    2013-07-01

    Elevated plasma levels of factor VIII (FVIII) are associated with increased risk of deep venous thrombosis. The aim of this study is to elucidate how elevated FVIII levels affect venous thrombus formation and propagation in vivo. We examined rabbit plasma FVIII activity, plasma thrombin generation, whole blood coagulation, platelet aggregation and venous wall thrombogenicity before and one hour after an intravenous infusion of recombinant human FVIII (rFVIII). Venous thrombus induced by the endothelial denudation of rabbit jugular veins was histologically assessed. Thrombus propagation was evaluated as indocyanine green fluorescence intensity. Argatroban, a thrombin inhibitor, and neutralised antibodies for tissue factor (TF), factor XI (FXI), and von Willebrand factor (VWF) were infused before or after thrombus induction to investigate their effects on venous thrombus formation or propagation. Recombinant FVIII (100 IU/kg) increased rabbit plasma FVIII activity two-fold and significantly enhanced whole blood coagulation and total plasma thrombin generation, but did not affect initial thrombin generation time, platelet aggregation and venous wall thrombogenicity. The rFVIII infusion also increased the size of venous thrombus 1 hour after thrombus induction. Argatroban and the antibodies for TF, FXI or VWF inhibited such enhanced thrombus formation and all except TF suppressed thrombus propagation. In conclusion, elevated plasma FVIII levels enhance venous thrombus formation and propagation. Excess thrombin generation by FXI and VWF-mediated FVIII recruitment appear to contribute to the growth of FVIII-driven venous thrombus.

  14. Glycinin-gum arabic complex formation: Turbidity measurement and charge neutralization analysis.

    PubMed

    Dong, Die; Hua, Yufei

    2016-11-01

    The interaction between glycinin and anionic polysaccharides has gained considerable attention recently because of its scientific impact on the stability of acid soymilk systems. In this study, the formation of glycinin/gum arabic complexes driven by electrostatic interactions was investigated. Turbidity titrations at different glycinin/gum arabic ratios were conducted and critical pH values (pH φ1 ) where insoluble complexes began forming were determined firstly. The corresponding pH φ1 values at glycinin/gum arabic ratios of 1:4, 1:2, 1:1, 2:1, 4:1 and 8:1 were 2.85, 3.25, 3.70, 4.40, 4.85 and 5.35, respectively. Afterwards, electromobilities for glycinin and gum arabic at the pH values between 4.1 and 2.6 were measured, and charge densities (ZN) for glycinin and gum arabic were calculated based on the soft particle analysis theory. Further analysis indicated that the product of glycinin/gum arabic ratio (ρ) and ZN ratio of glycinin/gum arabic was approximate 1 at any pH φ1 values. It was revealed that charge neutralization was achieved when glycinin/gum arabic insoluble complexes began forming. NaCl displayed multiple effects on glycinin/gum arabic complex formation according to turbidity and compositional analysis. The present study could provide basic guidance in acid soymilk designing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Cl-doping of Te-rich CdTe: Complex formation, self-compensation and self-purification from first principles

    NASA Astrophysics Data System (ADS)

    Lindström, A.; Klintenberg, M.; Sanyal, B.; Mirbt, S.

    2015-08-01

    The coexistence in Te-rich CdTe of substitutional Cl-dopants, ClTe, which act as donors, and Cd vacancies, VC d - 1 , which act as electron traps, was studied from first principles utilising the HSE06 hybrid functional. We find ClTe to preferably bind to VC d - 1 and to form an acceptor complex, (ClTe-VCd)-1. The complex has a (0,-1) charge transfer level close to the valence band and shows no trap state (deep level) in the band gap. During the complex formation, the defect state of VCd-1 is annihilated and leaves the Cl-doped CdTe bandgap without any trap states (self-purification). We calculate Cl-doped CdTe to be semi-insulating with a Fermi energy close to midgap. We calculate the formation energy of the complex to be sufficiently low to allow for spontanous defect formation upon Cl-doping (self-compensation). In addition, we quantitatively analyse the geometries, DOS, binding energies and formation energies of the (ClTe-VCd) complexes.

  16. Gold nanoparticles as a factor of influence on doxorubicin-bovine serum albumin complex

    NASA Astrophysics Data System (ADS)

    Goncharenko, N. A.; Pavlenko, O. L.; Dmytrenko, O. P.; Kulish, M. P.; Lopatynskyi, A. M.; Chegel, V. I.

    2018-04-01

    The interaction between doxorubicin (Dox) and bovine serum albumin (BSA) complex with gold nanoparticles (AuNPs) was investigated by optical spectroscopy. The optical absorption of Dox and BSA solutions was studied. The formation of Dox-BSA complexes with a binding constant K = 7.56 × 106 M-2 and the number of binding sites n = 2 was found out. With pH 6.9, the concentration of complexes is an order of magnitude lower than the concentration of unbound antibiotic molecules. Optical absorption in solutions of Dox-BSA conjugates in the presence of AuNPs undergoes a significant rearrangement, which manifests the changes in the magnitude of the hydrophobic interaction of BSA with Dox, changes in the conformational state of antibiotic, and, as a consequence, a plasmon-induced change in the mechanism of complex formation. The aggregation of the Dox-AuNPs conjugate depends on the presence and concentration of BSA and in the case of formation of the Dox-BSA complex is minimal.

  17. Social complexity as a proximate and ultimate factor in communicative complexity

    PubMed Central

    Freeberg, Todd M.; Dunbar, Robin I. M.; Ord, Terry J.

    2012-01-01

    The ‘social complexity hypothesis’ for communication posits that groups with complex social systems require more complex communicative systems to regulate interactions and relations among group members. Complex social systems, compared with simple social systems, are those in which individuals frequently interact in many different contexts with many different individuals, and often repeatedly interact with many of the same individuals in networks over time. Complex communicative systems, compared with simple communicative systems, are those that contain a large number of structurally and functionally distinct elements or possess a high amount of bits of information. Here, we describe some of the historical arguments that led to the social complexity hypothesis, and review evidence in support of the hypothesis. We discuss social complexity as a driver of communication and possible causal factor in human language origins. Finally, we discuss some of the key current limitations to the social complexity hypothesis—the lack of tests against alternative hypotheses for communicative complexity and evidence corroborating the hypothesis from modalities other than the vocal signalling channel. PMID:22641818

  18. Formation mechanism of complex pattern on fishes' skin

    NASA Astrophysics Data System (ADS)

    Li, Xia; Liu, Shuhua

    2009-10-01

    In this paper, the formation mechanism of the complex patterns observed on the skin of fishes has been investigated by a two-coupled reaction diffusion model. The effects of coupling strength between two layers play an important role in the pattern-forming process. It is found that only the epidermis layer can produce complicated patterns that have structures on more than one length scale. These complicated patterns including super-stripe pattern, mixture of spots and stripe, and white-eye pattern are similar to the pigmentation patterns on fishes' skin.

  19. Globular cluster formation with multiple stellar populations from hierarchical star cluster complexes

    NASA Astrophysics Data System (ADS)

    Bekki, Kenji

    2017-05-01

    Most old globular clusters (GCs) in the Galaxy are observed to have internal chemical abundance spreads in light elements. We discuss a new GC formation scenario based on hierarchical star formation within fractal molecular clouds. In the new scenario, a cluster of bound and unbound star clusters ('star cluster complex', SCC) that have a power-law cluster mass function with a slope (β) of 2 is first formed from a massive gas clump developed in a dwarf galaxy. Such cluster complexes and β = 2 are observed and expected from hierarchical star formation. The most massive star cluster ('main cluster'), which is the progenitor of a GC, can accrete gas ejected from asymptotic giant branch (AGB) stars initially in the cluster and other low-mass clusters before the clusters are tidally stripped or destroyed to become field stars in the dwarf. The SCC is initially embedded in a giant gas hole created by numerous supernovae of the SCC so that cold gas outside the hole can be accreted on to the main cluster later. New stars formed from the accreted gas have chemical abundances that are different from those of the original SCC. Using hydrodynamical simulations of GC formation based on this scenario, we show that the main cluster with the initial mass as large as [2-5] × 105 M⊙ can accrete more than 105 M⊙ gas from AGB stars of the SCC. We suggest that merging of hierarchical SSCs can play key roles in stellar halo formation around GCs and self-enrichment processes in the early phase of GC formation.

  20. Deciphering Front-Side Complex Formation in SN2 Reactions via Dynamics Mapping.

    PubMed

    Szabó, István; Olasz, Balázs; Czakó, Gábor

    2017-07-06

    Due to their importance in organic chemistry, the atomistic understanding of bimolecular nucleophilic substitution (S N 2) reactions shows exponentially growing interest. In this publication, the effect of front-side complex (FSC) formation is uncovered via quasi-classical trajectory computations combined with a novel analysis method called trajectory orthogonal projection (TOP). For both F - + CH 3 Y [Y = Cl,I] reactions, the lifetime distributions of the F - ···YCH 3 front-side complex revealed weakly trapped nucleophiles (F - ). However, only the F - + CH 3 I reaction features strongly trapped nucleophiles in the front-side region of the prereaction well. Interestingly, both back-side and front-side attack show propensity to long-lived FSC formation. Spatial distributions of the nucleophile demonstrate more prominent FSC formation in case of the F - + CH 3 I reaction compared to F - + CH 3 Cl. The presence of front-side intermediates and the broad spatial distribution in the back-side region may explain the indirect nature of the F - + CH 3 I reaction.

  1. Pattern Formation in Complex Fluids

    NASA Astrophysics Data System (ADS)

    Shelley, Michael

    2000-03-01

    Classical fluid instabilities -- such as the Saffman-Taylor instability in a Hele-Shaw cell -- are dramatically modified by using complex fluids. For example, polymeric liquids driven in a Hele-Shaw cell yield "dendritic" patterns with an apparent directional anisotropy. The dynamics of complex liquids can also lead to new instabilities and patterns, such as space-filling patterns formed by successive bucklings of growing "elastica" seen in the phase transition of a liquid crystalline material. Understanding such problems requires an interplay between physical modeling, mathematical analysis, and sophisticated nonlinear simulation. For the first problem, I will discuss a non-Newtonian version of Darcy's law for Hele-Shaw flow. This yields a free-boundary problem for the pattern formation, and requires the solution of a nonlinear elliptic equation in a time-dependent domain. This is pushing the development of adaptive grid methods that represent the geometry accurately and efficiently. Our simulations yield insight into how shear-thinning, as is evinced by polymeric liquids, can produce patterns reminiscent of experiment, with "dendritic fingers", side-branching, and reduced tip-splitting. In the second problem, a long filament in a smectic-A phase grows within an isotropic fluid. The splay deformation of the material gives this filament an elastic response. The macroscopic model describes the dynamics of a growing, elastic filament immersed in a Stokesian fluid. The model marries filament elasticity and tensile forces with a numerically tractable nonlocal slender-body theory. Analysis shows that growth of the filament, despite fluid drag, produces a buckling instability. When coupled to a nonlocal hydrodynamic self-interaction, our fully nonlinear simulations show that such instabilities iterate along the filament, and give "space-filling" patterns.

  2. Conformation-Directed Formation of Self-Healing Diblock Copolypeptide Hydrogels via Polyion Complexation.

    PubMed

    Sun, Yintao; Wollenberg, Alexander L; O'Shea, Timothy Mark; Cui, Yanxiang; Zhou, Z Hong; Sofroniew, Michael V; Deming, Timothy J

    2017-10-25

    Synthetic diblock copolypeptides were designed to incorporate oppositely charged ionic segments that form β-sheet-structured hydrogel assemblies via polyion complexation when mixed in aqueous media. The observed chain conformation directed assembly was found to be required for efficient hydrogel formation and provided distinct and useful properties to these hydrogels, including self-healing after deformation, microporous architecture, and stability against dilution in aqueous media. While many promising self-assembled materials have been prepared using disordered or liquid coacervate polyion complex (PIC) assemblies, the use of ordered chain conformations in PIC assemblies to direct formation of new supramolecular morphologies is unprecedented. The promising attributes and unique features of the β-sheet-structured PIC hydrogels described here highlight the potential of harnessing conformational order derived from PIC assembly to create new supramolecular materials.

  3. Synergistic effect of ATP for RuvA-RuvB-Holliday junction DNA complex formation.

    PubMed

    Iwasa, Takuma; Han, Yong-Woon; Hiramatsu, Ryo; Yokota, Hiroaki; Nakao, Kimiko; Yokokawa, Ryuji; Ono, Teruo; Harada, Yoshie

    2015-12-14

    The Escherichia coli RuvB hexameric ring motor proteins, together with RuvAs, promote branch migration of Holliday junction DNA. Zero mode waveguides (ZMWs) constitute of nanosized holes and enable the visualization of a single fluorescent molecule under micromolar order of the molecules, which is applicable to characterize the formation of RuvA-RuvB-Holliday junction DNA complex. In this study, we used ZMWs and counted the number of RuvBs binding to RuvA-Holliday junction DNA complex. Our data demonstrated that different nucleotide analogs increased the amount of Cy5-RuvBs binding to RuvA-Holliday junction DNA complex in the following order: no nucleotide, ADP, ATPγS, and mixture of ADP and ATPγS. These results suggest that not only ATP binding to RuvB but also ATP hydrolysis by RuvB facilitates a stable RuvA-RuvB-Holliday junction DNA complex formation.

  4. Studying of kinetics of rear earth ion (REI) nanoscale complex formation by resonant energy transfer

    NASA Astrophysics Data System (ADS)

    Ignatova, Tetyana; Pristinski, Denis; Rotkin, Slava V.

    2011-03-01

    We observed formation of nanoscale complexes between multivalent REIs (Tb and Eu) and negatively charged DNA wrapped SWNTs, ionized in the water solution. Foerster Resonance Energy Transfer (FRET) was found to be an ideal method to confirm the complex formation. Because of its high sensitivity and non-destructive characterization approach FRET can be used to trace the kinetics of the complex formation. Strong dependence of SWNT photoluminescence (PL) on the REI concentration was detected and interpreted as a competition between the REI absorption on the SWNTs and subsequent FRET enhanced PL and the SWNT agglomeration followed by PL quenching. We measured the distance between REI and SWNT which appears to be much shorter than the one from their relative concentration in solution. We speculate that Manning condensation of the REIs on the SWNT/DNA surface happens thereby significantly reducing their spacing and making FRET possible.

  5. The Effect of Complex Formation upon the Redox Potentials of Metallic Ions. Cyclic Voltammetry Experiments.

    ERIC Educational Resources Information Center

    Ibanez, Jorge G.; And Others

    1988-01-01

    Describes experiments in which students prepare in situ soluble complexes of metal ions with different ligands and observe and estimate the change in formal potential that the ion undergoes upon complexation. Discusses student formation and analysis of soluble complexes of two different metal ions with the same ligand. (CW)

  6. Studies on chalcone derivatives: complex formation, thermal behavior, stability constant and antioxidant activity.

    PubMed

    El-Sayed, Yusif S; Gaber, M

    2015-02-25

    The chalcone 3-[4'-dimethylaminophenyl]-1-(2-pyridyl) prop-2-en-1-one (DMAPP) and 3-(4'-diethylaminophenyl)-1-(2-pyridinyl) prop-2-en-1-one abbreviated as DEAPP have been synthesized and characterized with IR, (1)H NMR, (13)C NMR spectroscopic techniques as described previously (El-Daly et al., 2008; Gaber et al., 2009; El-Sayed, 2013). By using UV visible spectroscopy method the mole fraction ratio for copper with DMAPP and DEAPP complexes were determined and it was found to be 1:1. The stability constants of this complex have been determined by Job's method. The stability constant (Kf) of copper with DMAPP and DEAPP complexes in universal buffer pH=3.2 was determined to be 9.9×10(4) and 5.2×10(4) respectively. The effect of Cu(II) ion on the emission spectrum of the free chalcone is also assigned. Adherence to Beer's law and Ringbom optimum concentration ranges are determined. The thermal decomposition of the metal complexes is studied by TGA technique. The kinetic parameters like activation energy, pre-exponential factor and entropy of activation are estimated. The structure of complexes was energetically optimized through molecular mechanics applying MM(+) force field coupled with molecular dynamics simulation. The bond lengths and bond angles have been calculated to confirm the geometry of the ligands and their Cu(II) complexes. The mode of interaction of the chalcone to copper nanoparticles was studied. The apparent association constants of the colloidal copper nanoparticles:chalcone complexes in solution were evaluated using the spectral method and compared with the formation constant of the Cu(II) chalcone complexes. Antioxidant activity of these chalcones was evaluated by using 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radicals scavenging method, which showed that the antioxidant activity of DMAPP has higher value than the DEAPP. Semi-empirical study results showed that DMAPP have higher dipole moment than DEAPP. Copyright © 2014 Elsevier B.V. All rights

  7. Studies on chalcone derivatives: Complex formation, thermal behavior, stability constant and antioxidant activity

    NASA Astrophysics Data System (ADS)

    El-Sayed, Yusif S.; Gaber, M.

    2015-02-01

    The chalcone 3-[4‧-dimethylaminophenyl]-1-(2-pyridyl) prop-2-en-1-one (DMAPP) and 3-(4‧-diethylaminophenyl)-1-(2-pyridinyl) prop-2-en-1-one abbreviated as DEAPP have been synthesized and characterized with IR, 1H NMR, 13C NMR spectroscopic techniques as described previously (El-Daly et al., 2008; Gaber et al., 2009; El-Sayed, 2013). By using UV visible spectroscopy method the mole fraction ratio for copper with DMAPP and DEAPP complexes were determined and it was found to be 1:1. The stability constants of this complex have been determined by Job's method. The stability constant (Kf) of copper with DMAPP and DEAPP complexes in universal buffer pH = 3.2 was determined to be 9.9 × 104 and 5.2 × 104 respectively. The effect of Cu(II) ion on the emission spectrum of the free chalcone is also assigned. Adherence to Beer's law and Ringbom optimum concentration ranges are determined. The thermal decomposition of the metal complexes is studied by TGA technique. The kinetic parameters like activation energy, pre-exponential factor and entropy of activation are estimated. The structure of complexes was energetically optimized through molecular mechanics applying MM+ force field coupled with molecular dynamics simulation. The bond lengths and bond angles have been calculated to confirm the geometry of the ligands and their Cu(II) complexes. The mode of interaction of the chalcone to copper nanoparticles was studied. The apparent association constants of the colloidal copper nanoparticles:chalcone complexes in solution were evaluated using the spectral method and compared with the formation constant of the Cu(II) chalcone complexes. Antioxidant activity of these chalcones was evaluated by using 1,1‧-diphenyl-2-picrylhydrazyl (DPPHrad) radicals scavenging method, which showed that the antioxidant activity of DMAPP has higher value than the DEAPP. Semi-empirical study results showed that DMAPP have higher dipole moment than DEAPP [1].

  8. Natural Product Screening Reveals Naphthoquinone Complex I Bypass Factors

    PubMed Central

    Mevers, Emily; Higgins, Kathleen W.; Fomina, Yevgenia; Zhang, Jianming; Mandinova, Anna; Newman, David; Shaw, Stanley Y.; Clardy, Jon; Mootha, Vamsi K.

    2016-01-01

    Deficiency of mitochondrial complex I is encountered in both rare and common diseases, but we have limited therapeutic options to treat this lesion to the oxidative phosphorylation system (OXPHOS). Idebenone and menadione are redox-active molecules capable of rescuing OXPHOS activity by engaging complex I-independent pathways of entry, often referred to as “complex I bypass.” In the present study, we created a cellular model of complex I deficiency by using CRISPR genome editing to knock out Ndufa9 in mouse myoblasts, and utilized this cell line to develop a high-throughput screening platform for novel complex I bypass factors. We screened a library of ~40,000 natural product extracts and performed bioassay-guided fractionation on a subset of the top scoring hits. We isolated four plant-derived 1,4-naphthoquinone complex I bypass factors with structural similarity to menadione: chimaphilin and 3-chloro-chimaphilin from Chimaphila umbellata and dehydro-α-lapachone and dehydroiso-α-lapachone from Stereospermum euphoroides. We also tested a small number of structurally related naphthoquinones from commercial sources and identified two additional compounds with complex I bypass activity: 2-methoxy-1,4-naphthoquinone and 2-methoxy-3-methyl-1,4,-naphthoquinone. The six novel complex I bypass factors reported here expand this class of molecules and will be useful as tool compounds for investigating complex I disease biology. PMID:27622560

  9. In situ formation of heterobimetallic salen complexes containing titanium and/or vanadium ions.

    PubMed

    Belokon, Yuri N; Harrington, Ross W; North, Michael; Young, Carl

    2008-05-05

    A combination of high-resolution electrospray mass spectrometry and (1)H NMR spectroscopy has been used to prove that when a mixture of [(salen)TiO]2 complexes containing two different salen ligands (salen and salen') is formed, an equilibrium is established between the homodimers and the heterodimer [(salen)TiO2Ti(salen')]. Depending upon the structure and stereochemistry of the two salen ligands, the equilibrium may favor either the homodimers or the heterodimer. Extension of this process to mixtures of titanium(salen) complexes [(salen)TiO]2 and vanadium (V)(salen') complexes [(salen')VO] (+)Cl (-) allowed the in situ formation of the heterobimetallic complex [(salen)TiO2V(salen')] (+)X (-) to be confirmed for all combinations of salen ligands studied except when the salen ligand attached to titanium contained highly electron-withdrawing nitro-groups. The rate of equilibration between heterobimetallic complexes is faster than that between two titanium complexes as determined by line broadening in the (1)H NMR spectra. These structural results explain the strong rate-inhibiting effect of vanadium (V)(salen) complexes in asymmetric cyanohydrin synthesis catalyzed by [(salen)TiO]2 complexes. It has also been demonstrated for the first time that the titanium and vanadium complexes can undergo exchange of salen ligands and that this is catalyzed by protic solvents. However, the ligand exchange is relatively slow (occurring on a time scale of days at room temperature) and so does not complicate studies aimed at using heterobimetallic titanium and vanadium salen complexes as asymmetric catalysts. Attempts to obtain a crystal structure of a heterobimetallic salen complex led instead to the isolation of a trinuclear titanium(salen) complex, the formation of which is also consistent with the catalytic results obtained previously.

  10. Identification of amino acids that promote specific and rigid TAR RNA-tat protein complex formation.

    PubMed

    Edwards, Thomas E; Robinson, Bruce H; Sigurdsson, Snorri Th

    2005-03-01

    The Tat protein and the transactivation responsive (TAR) RNA form an essential complex in the HIV lifecycle, and mutations in the basic region of the Tat protein alter this RNA-protein molecular recognition. Here, EPR spectroscopy was used to identify amino acids, flanking an essential arginine of the Tat protein, which contribute to specific and rigid TAR-Tat complex formation by monitoring changes in the mobility of nitroxide spin-labeled TAR RNA nucleotides upon binding. Arginine to lysine N-terminal mutations did not affect TAR RNA interfacial dynamics. In contrast, C-terminal point mutations, R56 in particular, affected the mobility of nucleotides U23 and U38, which are involved in a base-triple interaction in the complex. This report highlights the role of dynamics in specific molecular complex formation and demonstrates the ability of EPR spectroscopy to study interfacial dynamics of macromolecular complexes.

  11. Oxidative Formation and Removal of Complexed Mn(III) by Pseudomonas Species

    PubMed Central

    Wright, Mitchell H.; Geszvain, Kati; Oldham, Véronique E.; Luther, George W.; Tebo, Bradley M.

    2018-01-01

    The observation of significant concentrations of soluble Mn(III) complexes in oxic, suboxic, and some anoxic waters has triggered a re-evaluation of the previous Mn paradigm which focused on the cycling between soluble Mn(II) and insoluble Mn(III,IV) species as operationally defined by filtration. Though Mn(II) oxidation in aquatic environments is primarily bacterially-mediated, little is known about the effect of Mn(III)-binding ligands on Mn(II) oxidation nor on the formation and removal of Mn(III). Pseudomonas putida GB-1 is one of the most extensively investigated of all Mn(II) oxidizing bacteria, encoding genes for three Mn oxidases (McoA, MnxG, and MopA). P. putida GB-1 and associated Mn oxidase mutants were tested alongside environmental isolates Pseudomonas hunanensis GSL-007 and Pseudomonas sp. GSL-010 for their ability to both directly oxidize weakly and strongly bound Mn(III), and to form these complexes through the oxidation of Mn(II). Using Mn(III)-citrate (weak complex) and Mn(III)-DFOB (strong complex), it was observed that P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 and mutants expressing only MnxG and McoA were able to directly oxidize both species at varying levels; however, no oxidation was detected in cultures of a P. putida mutant expressing only MopA. During cultivation in the presence of Mn(II) and citrate or DFOB, P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 formed Mn(III) complexes transiently as an intermediate before forming Mn(III/IV) oxides with the overall rates and extents of Mn(III,IV) oxide formation being greater for Mn(III)-citrate than for Mn(III)-DFOB. These data highlight the role of bacteria in the oxidative portion of the Mn cycle and suggest that the oxidation of strong Mn(III) complexes can occur through enzymatic mechanisms involving multicopper oxidases. The results support the observations from field studies and further emphasize the complexity of the geochemical cycling of

  12. Oxidative Formation and Removal of Complexed Mn(III) by Pseudomonas Species.

    PubMed

    Wright, Mitchell H; Geszvain, Kati; Oldham, Véronique E; Luther, George W; Tebo, Bradley M

    2018-01-01

    The observation of significant concentrations of soluble Mn(III) complexes in oxic, suboxic, and some anoxic waters has triggered a re-evaluation of the previous Mn paradigm which focused on the cycling between soluble Mn(II) and insoluble Mn(III,IV) species as operationally defined by filtration. Though Mn(II) oxidation in aquatic environments is primarily bacterially-mediated, little is known about the effect of Mn(III)-binding ligands on Mn(II) oxidation nor on the formation and removal of Mn(III). Pseudomonas putida GB-1 is one of the most extensively investigated of all Mn(II) oxidizing bacteria, encoding genes for three Mn oxidases (McoA, MnxG, and MopA). P. putida GB-1 and associated Mn oxidase mutants were tested alongside environmental isolates Pseudomonas hunanensis GSL-007 and Pseudomonas sp. GSL-010 for their ability to both directly oxidize weakly and strongly bound Mn(III), and to form these complexes through the oxidation of Mn(II). Using Mn(III)-citrate (weak complex) and Mn(III)-DFOB (strong complex), it was observed that P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 and mutants expressing only MnxG and McoA were able to directly oxidize both species at varying levels; however, no oxidation was detected in cultures of a P. putida mutant expressing only MopA. During cultivation in the presence of Mn(II) and citrate or DFOB, P. putida GB-1, P. hunanensis GSL-007 and Pseudomonas sp. GSL-010 formed Mn(III) complexes transiently as an intermediate before forming Mn(III/IV) oxides with the overall rates and extents of Mn(III,IV) oxide formation being greater for Mn(III)-citrate than for Mn(III)-DFOB. These data highlight the role of bacteria in the oxidative portion of the Mn cycle and suggest that the oxidation of strong Mn(III) complexes can occur through enzymatic mechanisms involving multicopper oxidases. The results support the observations from field studies and further emphasize the complexity of the geochemical cycling of

  13. The ribosome-associated complex antagonizes prion formation in yeast.

    PubMed

    Amor, Alvaro J; Castanzo, Dominic T; Delany, Sean P; Selechnik, Daniel M; van Ooy, Alex; Cameron, Dale M

    2015-01-01

    The number of known fungal proteins capable of switching between alternative stable conformations is steadily increasing, suggesting that a prion-like mechanism may be broadly utilized as a means to propagate altered cellular states. To gain insight into the mechanisms by which cells regulate prion formation and toxicity we examined the role of the yeast ribosome-associated complex (RAC) in modulating both the formation of the [PSI(+)] prion - an alternative conformer of Sup35 protein - and the toxicity of aggregation-prone polypeptides. The Hsp40 RAC chaperone Zuo1 anchors the RAC to ribosomes and stimulates the ATPase activity of the Hsp70 chaperone Ssb. We found that cells lacking Zuo1 are sensitive to over-expression of some aggregation-prone proteins, including the Sup35 prion domain, suggesting that co-translational protein misfolding increases in Δzuo1 strains. Consistent with this finding, Δzuo1 cells exhibit higher frequencies of spontaneous and induced prion formation. Cells expressing mutant forms of Zuo1 lacking either a C-terminal charged region required for ribosome association, or the J-domain responsible for Ssb ATPase stimulation, exhibit similarly high frequencies of prion formation. Our findings are consistent with a role for the RAC in chaperoning nascent Sup35 to regulate folding of the N-terminal prion domain as it emerges from the ribosome.

  14. Crystal structure and solution species of Ce(III) and Ce(IV) formates: from mononuclear to hexanuclear complexes.

    PubMed

    Hennig, Christoph; Ikeda-Ohno, Atsushi; Kraus, Werner; Weiss, Stephan; Pattison, Philip; Emerich, Hermann; Abdala, Paula M; Scheinost, Andreas C

    2013-10-21

    Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solution and the solid-state structures are surprisingly different. The species in aqueous solutions were investigated with Ce K-edge EXAFS spectroscopy. Ce(III) formate shows only mononuclear complexes, which is in agreement with the predicted mononuclear species of Ce(HCOO)(2+) and Ce(HCOO)2(+). In contrast, Ce(IV) formate forms in aqueous solution a stable hexanuclear complex of [Ce6(μ3-O)4(μ3-OH)4(HCOO)x(NO3)y](12-x-y). The structural differences reflect the different influence of hydrolysis, which is weak for Ce(III) and strong for Ce(IV). Hydrolysis of Ce(IV) ions causes initial polymerization while complexation through HCOO(-) results in 12 chelate rings stabilizing the hexanuclear Ce(IV) complex. Crystals were grown from the above-mentioned solutions. Two crystal structures of Ce(IV) formate were determined. Both form a hexanuclear complex with a [Ce6(μ3-O)4(μ3-OH)4](12+) core in aqueous HNO3/HCOOH solution. The pH titration with NaOH resulted in a structure with the composition [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)2(H2O)3]·(H2O)9.5, while the pH adjustment with NH3 resulted in [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)4]·(NO3)3(NH4)5(H2O)5. Furthermore, the crystal structure of Ce(III) formate, Ce(HCOO)3, was determined. The coordination polyhedron is a tricapped trigonal prism which is formed exclusively by nine HCOO(-) ligands. The hexanuclear Ce(IV) formate species from aqueous solution is widely preserved in the crystal structure, whereas the mononuclear solution species of Ce(III) formate undergoes a polymerization during the crystallization process.

  15. Factors leading to the formation of arc cloud complexes

    NASA Technical Reports Server (NTRS)

    Welshinger, Mark John; Brundidge, Kenneth C.

    1987-01-01

    A total of 12 mesoscale convective systems (MCSs) were investigated. The duration of the gust front, produced by each MCS, was used to classify the MCSs. Category 1 MCSs were defined as ones that produced a gust front and the gust front lasted for more than 6 h. There were 7 category 1 MCSs in the sample. Category 2 MCSs were defined as ones that produced a gust front and the gust front lasted for 6 h or less. There were 4 category 2 MCSs. The MCS of Case 12 was not categorized because the precipitation characteristics were similar to a squall line, rather than an MCS. All of the category 1 MCSs produced arc cloud complexes (ACCs), while only one of the category 2 MCSs produced an ACC. To determine if there were any differences in the characteristics between the MCSs of the two categories, composite analyses were accomplished. The analyses showed that there were significant differences in the characteristics of category 1 and 2 MCSs. Category 1 MCSs, on average, had higher thunderstorm heights, greater precipitation intensities, colder cloud top temperatures and produced larger magnitudes of surface divergence than category 2 MCSs.

  16. DNA Polymerase α Subunit Residues and Interactions Required for Efficient Initiation Complex Formation Identified by a Genetic Selection.

    PubMed

    Lindow, Janet C; Dohrmann, Paul R; McHenry, Charles S

    2015-07-03

    Biophysical and structural studies have defined many of the interactions that occur between individual components or subassemblies of the bacterial replicase, DNA polymerase III holoenzyme (Pol III HE). Here, we extended our knowledge of residues and interactions that are important for the first step of the replicase reaction: the ATP-dependent formation of an initiation complex between the Pol III HE and primed DNA. We exploited a genetic selection using a dominant negative variant of the polymerase catalytic subunit that can effectively compete with wild-type Pol III α and form initiation complexes, but cannot elongate. Suppression of the dominant negative phenotype was achieved by secondary mutations that were ineffective in initiation complex formation. The corresponding proteins were purified and characterized. One class of mutant mapped to the PHP domain of Pol III α, ablating interaction with the ϵ proofreading subunit and distorting the polymerase active site in the adjacent polymerase domain. Another class of mutation, found near the C terminus, interfered with τ binding. A third class mapped within the known β-binding domain, decreasing interaction with the β2 processivity factor. Surprisingly, mutations within the β binding domain also ablated interaction with τ, suggesting a larger τ binding site than previously recognized. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. Planktonic growth and biofilm formation profiles in Candida haemulonii species complex.

    PubMed

    Ramos, Lívia S; Oliveira, Simone S C; Souto, Xênia M; Branquinha, Marta H; Santos, André L S

    2017-10-01

    Candida haemulonii species complex have emerged as multidrug-resistant yeasts able to cause fungemia worldwide. However, very little is known regarding their physiology and virulence factors. In this context, planktonic growth and biofilm formation of Brazilian clinical isolates of Candida haemulonii (n = 5), Candida duobushaemulonii (n = 4), and Candida haemulonii var. vulnera (n = 3) were reported. Overall, the fungal planktonic growth curves in Sabouraud dextrose broth reached the exponential phase in 48 h at 37°C. All the clinical isolates formed biofilm on polystyrene in a time-dependent event, as judged by the parameters evaluated: biomass (crystal violet staining), metabolic activity (XTT reduction), and extracellular matrix (safranin incorporation). No statistically significant differences were observed when the average measurements among the three Candida species were compared regarding both planktonic and biofilm lifestyles; however, typical isolate-specific differences were clearly noticed in fungal growth kinetics. © The Author 2017. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Ketoprofen-β-cyclodextrin inclusion complexes formation by supercritical process technology

    NASA Astrophysics Data System (ADS)

    Sumarno, Rahim, Rizki; Trisanti, Prida Novarita

    2017-05-01

    Ketoprofen was a poorly soluble which anti-inflammatory, analgesic and antipyretic drug, solubility of which can be enchanced by form complexation with β-cyclodextrin. Besides that, the inclusion complex reduces the incidence of gastrointestinal side effect of drug. The aims of this research are to study the effect of H2O concentration in the supercritical carbondioxide and operation condition in the formation of ketoprofen-β-Cyclodextrin inclusion complex. This research was began by dissolved H2O in supercritical CO2 at 40°C and various saturation pressures. Then, dissolved H2O contacted with (1:5 w/w) ketoprofen-β-Cyclodextrin mixture at 50°C and various operation pressures. It called saturation process. Saturation was done for ±2 hours with agitation process and continued by decompression process. The products were characterized by drug Release, Differential Scanning Calorimetry (DCS) dan Scanning Electron Microscopy (SEM) analyses. The percentage from this work were 76,82%-89,99% for inclusion complexes. The percentage drug release of ketoprofen were 82,83%-88,36% on various inclusion pressure and various inclusion period.

  19. The POU homeodomain transcription factor POUM2 and broad complex isoform 2 transcription factor induced by 20-hydroxyecdysone collaboratively regulate vitellogenin gene expression and egg formation in the silkworm Bombyx mori.

    PubMed

    Lin, Y; Liu, H; Yang, C; Gu, J; Shen, G; Zhang, H; Chen, E; Han, C; Zhang, Y; Xu, Y; Wu, J; Xia, Q

    2017-10-01

    Vitellogenin (Vg) is a source of nutrition for embryo development. Our previous study showed that the silkworm (Bombyx mori) transcription factor broad complex isoform 2 (BmBrC-Z2) regulates gene expression of the Vg gene (BmVg) by induction with 20-hydroxyecdysone (20E). However, the mechanism by which 20E regulates BmVg expression was not clarified. In this study, cell transfection experiments showed that the BmVg promoter containing the POU homeodomain transcription factor POUM2 (POUM2) and BrC-Z2 cis-response elements (CREs) showed a more significant response to 20E than that harbouring only the BrC-Z2 or POUM2 CRE. An electrophoretic mobility shift assay and chromatin immunoprecipitation assay showed that BmPOUM2 could bind to the POUM2 CRE of the BmVg promoter. Over-expression of BmPOUM2 and BmBrC-Z2 in B. mori embryo-derived cell line (BmE) could enhance the activity of the BmVg promoter carrying both the POUM2 and BrC-Z2 CREs following 20E induction. Quantitative PCR and immunofluorescence histochemistry showed that the expression pattern and tissue localization of BmPOUM2 correspond to those of BmVg. Glutathione S-transferase pull-down and co-immunoprecipitation assays confirmed that BmPOUM2 interacts only with BmBrC-Z2 to regulate BmVg expression. Down-regulation of BmPOUM2 in female silkworm by RNA interference significantly reduced BmVg expression, leading to abnormal egg formation. In summary, these results indicate that BmPOUM2 binds only to BmBrC-Z2 to collaboratively regulate BmVg expression by 20E induction to control vitellogenesis and egg formation in the silkworm. Moreover, these findings suggest that homeodomain protein POUM2 plays a novel role in regulating insect vitellogenesis. © 2017 The Royal Entomological Society.

  20. Star formation in a hierarchical model for Cloud Complexes

    NASA Astrophysics Data System (ADS)

    Sanchez, N.; Parravano, A.

    The effects of the external and initial conditions on the star formation processes in Molecular Cloud Complexes are examined in the context of a schematic model. The model considers a hierarchical system with five predefined phases: warm gas, neutral gas, low density molecular gas, high density molecular gas and protostars. The model follows the mass evolution of each substructure by computing its mass exchange with their parent and children. The parent-child mass exchange depends on the radiation density at the interphase, which is produced by the radiation coming from the stars that form at the end of the hierarchical structure, and by the external radiation field. The system is chaotic in the sense that its temporal evolution is very sensitive to small changes in the initial or external conditions. However, global features such as the star formation efficience and the Initial Mass Function are less affected by those variations.

  1. Levels of control exerted by the Isc iron-sulfur cluster system on biosynthesis of the formate hydrogenlyase complex.

    PubMed

    Pinske, Constanze; Jaroschinsky, Monique; Sawers, R Gary

    2013-06-01

    The membrane-associated formate hydrogenlyase (FHL) complex of bacteria like Escherichia coli is responsible for the disproportionation of formic acid into the gaseous products carbon dioxide and dihydrogen. It comprises minimally seven proteins including FdhF and HycE, the catalytic subunits of formate dehydrogenase H and hydrogenase 3, respectively. Four proteins of the FHL complex have iron-sulphur cluster ([Fe-S]) cofactors. Biosynthesis of [Fe-S] is principally catalysed by the Isc or Suf systems and each comprises proteins for assembly and for delivery of [Fe-S]. This study demonstrates that the Isc system is essential for biosynthesis of an active FHL complex. In the absence of the IscU assembly protein no hydrogen production or activity of FHL subcomponents was detected. A deletion of the iscU gene also resulted in reduced intracellular formate levels partially due to impaired synthesis of pyruvate formate-lyase, which is dependent on the [Fe-S]-containing regulator FNR. This caused reduced expression of the formate-inducible fdhF gene. The A-type carrier (ATC) proteins IscA and ErpA probably deliver [Fe-S] to specific apoprotein components of the FHL complex because mutants lacking either protein exhibited strongly reduced hydrogen production. Neither ATC protein could compensate for the lack of the other, suggesting that they had independent roles in [Fe-S] delivery to complex components. Together, the data indicate that the Isc system modulates FHL complex biosynthesis directly by provision of [Fe-S] as well as indirectly by influencing gene expression through the delivery of [Fe-S] to key regulators and enzymes that ultimately control the generation and oxidation of formate.

  2. Assembly and activation of neurotrophic factor receptor complexes.

    PubMed

    Simi, Anastasia; Ibáñez, Carlos F

    2010-04-01

    Neurotrophic factors play important roles in the development and function of both neuronal and glial elements of the central and peripheral nervous systems. Their functional diversity is in part based on their ability to interact with alternative complexes of receptor molecules. This review focuses on our current understanding of the mechanisms that govern the assembly and activation of neurotrophic factor receptor complexes. The realization that many, if not the majority, of these complexes exist in a preassembled form at the plasma membrane has forced the revision of classical ligand-mediated oligomerization models, and led to the discovery of novel mechanisms of receptor activation and generation of signaling diversity which are likely to be shared by many different classes of receptors.

  3. Inhibition of ribosome recruitment induces stress granule formation independently of eukaryotic initiation factor 2alpha phosphorylation.

    PubMed

    Mazroui, Rachid; Sukarieh, Rami; Bordeleau, Marie-Eve; Kaufman, Randal J; Northcote, Peter; Tanaka, Junichi; Gallouzi, Imed; Pelletier, Jerry

    2006-10-01

    Cytoplasmic aggregates known as stress granules (SGs) arise as a consequence of cellular stress and contain stalled translation preinitiation complexes. These foci are thought to serve as sites of mRNA storage or triage during the cell stress response. SG formation has been shown to require induction of eukaryotic initiation factor (eIF)2alpha phosphorylation. Herein, we investigate the potential role of other initiation factors in this process and demonstrate that interfering with eIF4A activity, an RNA helicase required for the ribosome recruitment phase of translation initiation, induces SG formation and that this event is not dependent on eIF2alpha phosphorylation. We also show that inhibition of eIF4A activity does not impair the ability of eIF2alpha to be phosphorylated under stress conditions. Furthermore, we observed SG assembly upon inhibition of cap-dependent translation after poliovirus infection. We propose that SG modeling can occur via both eIF2alpha phosphorylation-dependent and -independent pathways that target translation initiation.

  4. Inhibition of Ribosome Recruitment Induces Stress Granule Formation Independently of Eukaryotic Initiation Factor 2α Phosphorylation

    PubMed Central

    Mazroui, Rachid; Sukarieh, Rami; Bordeleau, Marie-Eve; Kaufman, Randal J.; Northcote, Peter; Tanaka, Junichi; Gallouzi, Imed

    2006-01-01

    Cytoplasmic aggregates known as stress granules (SGs) arise as a consequence of cellular stress and contain stalled translation preinitiation complexes. These foci are thought to serve as sites of mRNA storage or triage during the cell stress response. SG formation has been shown to require induction of eukaryotic initiation factor (eIF)2α phosphorylation. Herein, we investigate the potential role of other initiation factors in this process and demonstrate that interfering with eIF4A activity, an RNA helicase required for the ribosome recruitment phase of translation initiation, induces SG formation and that this event is not dependent on eIF2α phosphorylation. We also show that inhibition of eIF4A activity does not impair the ability of eIF2α to be phosphorylated under stress conditions. Furthermore, we observed SG assembly upon inhibition of cap-dependent translation after poliovirus infection. We propose that SG modeling can occur via both eIF2α phosphorylation-dependent and -independent pathways that target translation initiation. PMID:16870703

  5. Identification of regulatory targets for the bacterial Nus factor complex.

    PubMed

    Baniulyte, Gabriele; Singh, Navjot; Benoit, Courtney; Johnson, Richard; Ferguson, Robert; Paramo, Mauricio; Stringer, Anne M; Scott, Ashley; Lapierre, Pascal; Wade, Joseph T

    2017-12-11

    Nus factors are broadly conserved across bacterial species, and are often essential for viability. A complex of five Nus factors (NusB, NusE, NusA, NusG and SuhB) is considered to be a dedicated regulator of ribosomal RNA folding, and has been shown to prevent Rho-dependent transcription termination. Here, we identify an additional cellular function for the Nus factor complex in Escherichia coli: repression of the Nus factor-encoding gene, suhB. This repression occurs primarily by translation inhibition, followed by Rho-dependent transcription termination. Thus, the Nus factor complex can prevent or promote Rho activity depending on the gene context. Conservation of putative NusB/E binding sites upstream of Nus factor genes suggests that Nus factor autoregulation occurs in many bacterial species. Additionally, many putative NusB/E binding sites are also found upstream of other genes in diverse species, and we demonstrate Nus factor regulation of one such gene in Citrobacter koseri. We conclude that Nus factors have an evolutionarily widespread regulatory function beyond ribosomal RNA, and that they are often autoregulatory.

  6. Risk factors for granuloma formation in children induced by tracheobronchial foreign bodies.

    PubMed

    Huang, Zhenghua; Zhou, Ai; Zhang, Jianya; Xie, Lisheng; Li, Qi

    2015-12-01

    The aim of this study was to analyze the risk factors for granuloma formation caused by plant-based tracheobronchial foreign bodies in children, and investigate the underlying pathogenesis. In this retrospective analysis of 153 cases with tracheobronchial foreign bodies (peanuts and watermelon seeds), 35 cases of granuloma formation as granulation group (G), and 118 cases of no granuloma formation as non-granulation group (NG) were studied. Clinical data pertaining to sex (S), age (A), foreign body surface smoothness (SF), foreign body shape (SH), foreign body oil release state (O), the location of foreign bodies (L), and foreign body retention time (T) were collected for statistical analysis. Univariate analysis showed no significant difference between the two groups (G and NG) with respect to S, A, SH and L. Significant factors based on univariate analysis included SF, O and T. Multivariate logistic regression analysis revealed that SF and T were independent risk factors associated with development of granuloma. SF, O and T had relationship with the granuloma formation. Local trauma caused by an irregular and sharp foreign body, and extended period of time represent the main factors causing granuloma formation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  7. Electrocatalytic Oxidation of Formate by [Ni(P R 2N R' 2) 2(CH 3CN)] 2+ Complexes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Galan, Brandon R.; Schöffel, Julia; Linehan, John C.

    2011-08-17

    [Ni(P R 2N R' 2) 2(CH 3CN)] 2+ complexes with R = Ph, R' = 4-MeOPh or R = Cy, R' = Ph , and a mixed-ligand [Ni(P R 2N R' 2)(P R" 2N R' 2)(CH 3CN)] 2+ with R = Cy, R' = Ph, R" = Ph, have been synthesized and characterized by single-crystal X-ray crystallography. These and previously reported complexes are shown to be electrocatalysts for the oxidation of formate in solution to produce CO 2, protons, and electrons, with rates that are first-order in catalyst and formate at formate concentrations below ~0.04 M (34 equiv). At concentrationsmore » above ~0.06 M formate (52 equiv), catalytic rates become nearly independent of formate concentration. For the catalysts studied, maximum observed turnover frequencies vary from <1.1 to 15.8 s –1 at room temperature, which are the highest rates yet reported for formate oxidation by homogeneous catalysts. These catalysts are the only base-metal electrocatalysts as well as the only homogeneous electrocatalysts reported to date for the oxidation of formate. An acetate complex demonstrating an η 1-OC(O)CH 3 binding mode to nickel has also been synthesized and characterized by single-crystal X-ray crystallography. Based on this structure and the electrochemical and spectroscopic data, a mechanistic scheme for electrocatalytic formate oxidation is proposed which involves formate binding followed by a rate-limiting proton and two-electron transfer step accompanied by CO 2 liberation. Finally, the pendant amines have been demonstrated to be essential for electrocatalysis, as no activity toward formate oxidation was observed for the similar [Ni(depe) 2] 2+ (depe = 1,2-bis(diethylphosphino)ethane) complex.« less

  8. Electrocatalytic oxidation of formate by [Ni(P(R)2N(R')2)2(CH3CN)]2+ complexes.

    PubMed

    Galan, Brandon R; Schöffel, Julia; Linehan, John C; Seu, Candace; Appel, Aaron M; Roberts, John A S; Helm, Monte L; Kilgore, Uriah J; Yang, Jenny Y; DuBois, Daniel L; Kubiak, Clifford P

    2011-08-17

    [Ni(P(R)(2)N(R')(2))(2)(CH(3)CN)](2+) complexes with R = Ph, R' = 4-MeOPh or R = Cy, R' = Ph , and a mixed-ligand [Ni(P(R)(2)N(R')(2))(P(R''(2))N(R'(2)))(CH(3)CN)](2+) with R = Cy, R' = Ph, R'' = Ph, have been synthesized and characterized by single-crystal X-ray crystallography. These and previously reported complexes are shown to be electrocatalysts for the oxidation of formate in solution to produce CO(2), protons, and electrons, with rates that are first-order in catalyst and formate at formate concentrations below ∼0.04 M (34 equiv). At concentrations above ∼0.06 M formate (52 equiv), catalytic rates become nearly independent of formate concentration. For the catalysts studied, maximum observed turnover frequencies vary from <1.1 to 15.8 s(-1) at room temperature, which are the highest rates yet reported for formate oxidation by homogeneous catalysts. These catalysts are the only base-metal electrocatalysts as well as the only homogeneous electrocatalysts reported to date for the oxidation of formate. An acetate complex demonstrating an η(1)-OC(O)CH(3) binding mode to nickel has also been synthesized and characterized by single-crystal X-ray crystallography. Based on this structure and the electrochemical and spectroscopic data, a mechanistic scheme for electrocatalytic formate oxidation is proposed which involves formate binding followed by a rate-limiting proton and two-electron transfer step accompanied by CO(2) liberation. The pendant amines have been demonstrated to be essential for electrocatalysis, as no activity toward formate oxidation was observed for the similar [Ni(depe)(2)](2+) (depe = 1,2-bis(diethylphosphino)ethane) complex.

  9. Recrystallized Impact Glasses of the Onaping Formation and the Sudbury Igneous Complex, Sudbury Structure, Ontario, Canada

    NASA Technical Reports Server (NTRS)

    Dressler, B. O.; Weiser, T.; Brockmeyer, P.

    1996-01-01

    The origin of the Sudbury Structure and of the associated heterolithic breccias of the Onaping Formation and the Sudbury Igneous Complex have been controversial. While an impact origin of the structure has gained wide acceptance over the last 15 years, the origin of the recrystallized Onaping Formation glasses and of the igneous complex is still being debated. Recently the interpretation of the breccias of the Onaping Formation as suevitic fall-back impact breccias has been challenged. The igneous complex is interpreted either as a differentiated impact melt sheet or as a combination of an upper impact melt represented by the granophyre, and a lower, impact-triggered magmatic body consisting of the norite-sublayer formations. The Onaping Formation contains glasses as fluidal and nonfluidal fragments of various shapes and sizes. They are recrystallized, and our research indicates that they are petrographically heterogeneous and span a wide range of chemical compositions. These characteristics are not known from glasses of volcanic deposits. This suggests an origin by shock vitrification, an interpretation consistent with their association with numerous and varied country rock clasts that exhibit microscopic shock metamorphic features. The recrystallized glass fragments represent individual solid-state and liquid-state vitrified rocks or relatively small melt pods. The basal member lies beneath the Gray and Black members of the Onaping Formation and, where not metamorphic, has an igneous matrix. Igneous-textured melt bodies occur in the upper two members and above the Basal Member. A comparison of the chemical compositions of recrystallized glasses and of the matrices of the Basal Member and the melt bodies with the components and the bulk composition of the igneous complex is inconclusive as to the origin of the igneous complex. Basal Member matrix and Melt Bodies, on average, are chemically similar to the granophyre of the Sudbury Igneous Complex, suggesting that

  10. Drop formation, pinch-off dynamics and liquid transfer of simple and complex fluids

    NASA Astrophysics Data System (ADS)

    Dinic, Jelena; Sharma, Vivek

    Liquid transfer and drop formation processes underlying jetting, spraying, coating, and printing - inkjet, screen, roller-coating, gravure, nanoimprint hot embossing, 3D - often involve formation of unstable columnar necks. Capillary-driven thinning of such necks and their pinchoff dynamics are determined by a complex interplay of inertial, viscous and capillary stresses for simple, Newtonian fluids. Micro-structural changes in response to extensional flow field that arises within the thinning neck give rise to additional viscoelastic stresses in complex, non- Newtonian fluids. Using FLOW-3D, we simulate flows realized in prototypical geometries (dripping and liquid bridge stretched between two parallel plates) used for studying pinch-off dynamics and influence of microstructure and viscoelasticity. In contrast with often-used 1D or 2D models, FLOW-3D allows a robust evaluation of the magnitude of the underlying stresses and extensional flow field (both uniformity and magnitude). We find that the simulated radius evolution profiles match the pinch-off dynamics that are experimentally-observed and theoretically-predicted for model Newtonian fluids and complex fluids.

  11. Objective measurement of complex multimodal and multidimensional display formats: a common metric for predicting format effectiveness

    NASA Astrophysics Data System (ADS)

    Marshak, William P.; Darkow, David J.; Wesler, Mary M.; Fix, Edward L.

    2000-08-01

    Computer-based display designers have more sensory modes and more dimensions within sensory modality with which to encode information in a user interface than ever before. This elaboration of information presentation has made measurement of display/format effectiveness and predicting display/format performance extremely difficult. A multivariate method has been devised which isolates critical information, physically measures its signal strength, and compares it with other elements of the display, which act like background noise. This common Metric relates signal-to-noise ratios (SNRs) within each stimulus dimension, then combines SNRs among display modes, dimensions and cognitive factors can predict display format effectiveness. Examples with their Common Metric assessment and validation in performance will be presented along with the derivation of the metric. Implications of the Common Metric in display design and evaluation will be discussed.

  12. Computer analysis of potentiometric data of complexes formation in the solution

    NASA Astrophysics Data System (ADS)

    Jastrzab, Renata; Kaczmarek, Małgorzata T.; Tylkowski, Bartosz; Odani, Akira

    2018-02-01

    The determination of equilibrium constants is an important process for many branches of chemistry. In this review we provide the readers with a discussion on computer methods which have been applied for elaboration of potentiometric experimental data generated during complexes formation in solution. The review describes both: general basis of modeling tools and examples of the use of calculated stability constants.

  13. Tissue Factor-Factor VII Complex As a Key Regulator of Ovarian Cancer Phenotypes.

    PubMed

    Koizume, Shiro; Miyagi, Yohei

    2015-01-01

    Tissue factor (TF) is an integral membrane protein widely expressed in normal human cells. Blood coagulation factor VII (fVII) is a key enzyme in the extrinsic coagulation cascade that is predominantly secreted by hepatocytes and released into the bloodstream. The TF-fVII complex is aberrantly expressed on the surface of cancer cells, including ovarian cancer cells. This procoagulant complex can initiate intracellular signaling mechanisms, resulting in malignant phenotypes. Cancer tissues are chronically exposed to hypoxia. TF and fVII can be induced in response to hypoxia in ovarian cancer cells at the gene expression level, leading to the autonomous production of the TF-fVII complex. Here, we discuss the roles of the TF-fVII complex in the induction of malignant phenotypes in ovarian cancer cells. The hypoxic nature of ovarian cancer tissues and the roles of TF expression in endometriosis are discussed. Arguments will be extended to potential strategies to treat ovarian cancers based on our current knowledge of TF-fVII function.

  14. Triggers for β-sheet formation at the hydrophobic-hydrophilic interface: high concentration, in-plane orientational order, and metal ion complexation.

    PubMed

    Hoernke, Maria; Falenski, Jessica A; Schwieger, Christian; Koksch, Beate; Brezesinski, Gerald

    2011-12-06

    Amyloid formation plays a causative role in neurodegenerative diseases such as Alzheimer's disease or Parkinson's disease. Soluble peptides form β-sheets that subsequently rearrange into fibrils and deposit as amyloid plaques. Many parameters trigger and influence the onset of the β-sheet formation. Early stages are recently discussed to be cell-toxic. Aiming at understanding various triggers such as interactions with hydrophobic-hydrophilic interfaces and metal ion complexation and their interplay, we investigated a set of model peptides at the air-water interface. We are using a general approach to a variety of diseases such as Alzheimer's disease, Parkinson's disease, and type II diabetes that are connected to amyloid formation. Surface sensitive techniques combined with film balance measurements have been used to assess the conformation of the peptides and their orientation at the air-water interface (IR reflection-absorption spectroscopy). Additionally, the structures of the peptide layers were characterized by grazing incidence X-ray diffraction and X-ray reflectivity. The peptides adsorb to the air-water interface and immediately adopt an α-helical conformation. This helical intermediate transforms into β-sheets upon further triggering. The factors that result in β-sheet formation are dependent on the peptide sequence. In general, the interface has the strongest effect on peptide conformation compared to high concentrations or metal ions. Metal ions are able to prevent aggregation in bulk but not at the interface. At the interface, metal ion complexation has only minor effects on the peptide secondary structure, influencing the in-plane structure that is formed in two dimensions. At the air-water interface, increased concentrations or a parallel arrangement of the α-helical intermediates are the most effective triggers. This study reveals the role of various triggers for β-sheet formation and their complex interplay. Our main finding is that the

  15. Cross-talk between the Tissue Factor/coagulation factor VIIa complex and the tyrosine kinase receptor EphA2 in cancer.

    PubMed

    Eriksson, Oskar; Thulin, Åsa; Asplund, Anna; Hegde, Geeta; Navani, Sanjay; Siegbahn, Agneta

    2016-05-31

    Tissue Factor (TF) forms a proteolytically active complex together with coagulation factor VIIa (FVIIa) and functions as the trigger of blood coagulation or alternatively activates cell signaling. We recently described that EphA2 of the Eph tyrosine kinase receptor family is cleaved directly by the TF/FVIIa complex. The aim of the present study was to further characterize the cross-talk between TF/FVIIa and EphA2 using in vitro model systems and human cancer specimens. Cleavage and phosphorylation of EphA2 was studied by Western blot. Subcellular localization of TF and EphA2 was investigated by a proximity ligation assay and confocal microscopy. Phalloidin staining of the actin cytoskeleton was used to study cell rounding and retraction fiber formation. Expression of TF and EphA2 in human colorectal cancer specimens was examined by immunohistochemistry. TF and EphA2 co-localized constitutively in MDA-MB-231 cells, and addition of FVIIa resulted in cleavage of EphA2 by a PAR2-independent mechanism. Overexpression of TF in U251 glioblastoma cells lead to co-localization with EphA2 at the leading edge and FVIIa-dependent cleavage of EphA2. FVIIa potentiated ephrin-A1-induced cell rounding and retraction fiber formation in MDA-MB-231 cells through a RhoA/ROCK-dependent pathway that did not require PAR2-activation. TF and EphA2 were expressed in colorectal cancer specimens, and were significantly correlated. These results suggest that TF/FVIIa-EphA2 cross-talk might potentiate ligand-dependent EphA2 signaling in human cancers, and provide initial evidence that it is possible for this interaction to occur in vivo.

  16. Flo11p-Independent Control of “Mat” Formation by Hsp70 Molecular Chaperones and Nucleotide Exchange Factors in Yeast

    PubMed Central

    Martineau, Céline N.; Beckerich, Jean-Marie; Kabani, Mehdi

    2007-01-01

    The yeast Saccharomyces cerevisiae has been used as a model for fungal biofilm formation due to its ability to adhere to plastic surfaces and to form mats on low-density agar petri plates. Mats are complex multicellular structures composed of a network of cables that form a central hub from which emanate multiple radial spokes. This reproducible and elaborate pattern is indicative of a highly regulated developmental program that depends on specific transcriptional programming, environmental cues, and possibly cell–cell communication systems. While biofilm formation and sliding motility were shown to be strictly dependent on the cell-surface adhesin Flo11p, little is known about the cellular machinery that controls mat formation. Here we show that Hsp70 molecular chaperones play key roles in this process with the assistance of the nucleotide exchange factors Fes1p and Sse1p and the Hsp40 family member Ydj1p. The disruption of these cofactors completely abolished mat formation. Furthermore, complex interactions among SSA genes were observed: mat formation depended mostly on SSA1 while minor defects were observed upon loss of SSA2; additional mutations in SSA3 or SSA4 further enhanced these phenotypes. Importantly, these mutations did not compromise invasive growth or Flo11p expression, suggesting that Flo11p-independent pathways are necessary to form mats. PMID:17947402

  17. S100A13-C2A binary complex structure-a key component in the acidic fibroblast growth factor for the non-classical pathway

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mohan, Sepuru K.; Rani, Sandhya G.; Kumar, Sriramoju M.

    2009-03-13

    Fibroblast growth factors (FGFs) are key regulators of cell proliferation, differentiation, tumor-induced angiogenesis and migration. FGFs are essential for early embryonic development, organ formation and angiogenesis. They play important roles in tumor formation, inflammation, wound healing and restenosis. The biological effects of FGFs are mediated through the activation of the four transmembrane phosphotyrosine kinase receptors (FGFRs) in the presence of heparin sulfate proteoglycans (HSPGs) and therefore require the release of FGFs into the extracellular space. However, FGF-1 lacks the signal peptide required for the releasing of these proteins through the classical endoplasmic reticulum (ER)-Golgi secretary pathway. Maciag et al. demonstratedmore » that FGF-1 is exported through a non-classical release pathway involving the formation of a specific multiprotein complex [M. Landriscina, R. Soldi, C. Bagala, I. Micucci, S. Bellum, F. Tarantini, I. Prudovsky, T. Maciag, S100A13 participates in the release of fibroblast growth factor 1 in response to heat shock in vitro, J. Biol. Chem. 276 (2001) 22544-22552; C.M. Carreira, T.M. LaVallee, F. Tarantini, A. Jackson, J.T. Lathrop, B. Hampton, W.H. Burgess, T. Maciag, S100A13 is involved in the regulation of fibroblast growth factor-1 and p40 synaptotagmin-1 release in vitro, J. Biol. Chem. 273 (1998) 22224-22231; T.M. LaValle, F. Tarantini, S. Gamble, C.M. Carreira, A. Jackson, T. Maciag, Synaptotagmin-1 is required for fibroblast growth factor-1 release, J. Biol. Chem. 273 (1998) 22217-22223; C. Bagala, V. Kolev, A. Mandinova, R. Soldi, C. Mouta, I. Graziani, I, Prudovsky, T. Maciag, The alternative translation of synaptotagmin 1 mediates the non-classical release of FGF1, Biochem. Biophys. Res. Commun. 310 (2003) 1041-1047]. The protein constituents of this complex include FGF-1, S100A13 (a Ca{sup 2+}-binding protein), and the p40 form of synaptotagmin 1 (Syt1). To understand the molecular events in the FGF-1

  18. Transforming Growth Factor-β-Activated Kinase 1 Is Required for Human FcγRIIIb-Induced Neutrophil Extracellular Trap Formation.

    PubMed

    Alemán, Omar Rafael; Mora, Nancy; Cortes-Vieyra, Ricarda; Uribe-Querol, Eileen; Rosales, Carlos

    2016-01-01

    Neutrophils (PMNs) are the most abundant leukocytes in the blood. PMN migrates from the circulation to sites of infection where they are responsible for antimicrobial functions. PMN uses phagocytosis, degranulation, and formation of neutrophil extracellular traps (NETs) to kill microbes. Several stimuli, including bacteria, fungi, and parasites, and some pharmacological compounds, such as Phorbol 12-myristate 13-acetate (PMA), are efficient inducers of NETs. Antigen-antibody complexes are also capable of inducing NET formation. Recently, it was reported that FcγRIIIb cross-linking induced NET formation similarly to PMA stimulation. Direct cross-linking of FcγRIIA or integrins did not promote NET formation. FcγRIIIb-induced NET formation presented different kinetics from PMA-induced NET formation, suggesting differences in signaling. Because FcγRIIIb also induces a strong activation of extracellular signal-regulated kinase (ERK) and nuclear factor Elk-1, and the transforming growth factor-β-activated kinase 1 (TAK1) has recently been implicated in ERK signaling, in the present report, we explored the role of TAK1 in the signaling pathway activated by FcγRIIIb leading to NET formation. FcγRIIIb was stimulated by specific monoclonal antibodies, and NET formation was evaluated in the presence or absence of pharmacological inhibitors. The antibiotic LL Z1640-2, a selective inhibitor of TAK1 prevented FcγRIIIb-induced, but not PMA-induced NET formation. Both PMA and FcγRIIIb cross-linking induced phosphorylation of ERK. But, LL Z1640-2 only inhibited the FcγRIIIb-mediated activation of ERK. Also, only FcγRIIIb, similarly to transforming growth factor-β-induced TAK1 phosphorylation. A MEK (ERK kinase)-specific inhibitor was able to prevent ERK phosphorylation induced by both PMA and FcγRIIIb. These data show for the first time that FcγRIIIb cross-linking activates TAK1, and that this kinase is required for triggering the MEK/ERK signaling pathway to NETosis.

  19. Low-complexity and modulation-format-independent carrier phase estimation scheme using linear approximation for elastic optical networks

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Chen, Xue; Shi, Sheping; Sun, Erkun; Shi, Chen

    2018-03-01

    We propose a low-complexity and modulation-format-independent carrier phase estimation (CPE) scheme based on two-stage modified blind phase search (MBPS) with linear approximation to compensate the phase noise of arbitrary m-ary quadrature amplitude modulation (m-QAM) signals in elastic optical networks (EONs). Comprehensive numerical simulations are carried out in the case that the highest possible modulation format in EONs is 256-QAM. The simulation results not only verify its advantages of higher estimation accuracy and modulation-format independence, i.e., universality, but also demonstrate that the implementation complexity is significantly reduced by at least one-fourth in comparison with the traditional BPS scheme. In addition, the proposed scheme shows similar laser linewidth tolerance with the traditional BPS scheme. The slightly better OSNR performance of the scheme is also experimentally validated for PM-QPSK and PM-16QAM systems, respectively. The coexistent advantages of low-complexity and modulation-format-independence could make the proposed scheme an attractive candidate for flexible receiver-side DSP unit in EONs.

  20. Formation factor in Bentheimer and Fontainebleau sandstones: Theory compared with pore-scale numerical simulations

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Behzad; Berg, Carl F.

    2017-09-01

    Accurate quantification of formation resistivity factor F (also called formation factor) provides useful insight into connectivity and pore space topology in fully saturated porous media. In particular the formation factor has been extensively used to estimate permeability in reservoir rocks. One of the widely applied models to estimate F is Archie's law (F = ϕ- m in which ϕ is total porosity and m is cementation exponent) that is known to be valid in rocks with negligible clay content, such as clean sandstones. In this study we compare formation factors determined by percolation and effective-medium theories as well as Archie's law with numerical simulations of electrical resistivity on digital rock models. These digital models represent Bentheimer and Fontainebleau sandstones and are derived either by reconstruction or directly from micro-tomographic images. Results show that the universal quadratic power law from percolation theory accurately estimates the calculated formation factor values in network models over the entire range of porosity. However, it crosses over to the linear scaling from the effective-medium approximation at the porosity of 0.75 in grid models. We also show that the effect of critical porosity, disregarded in Archie's law, is nontrivial, and the Archie model inaccurately estimates the formation factor in low-porosity homogeneous sandstones.

  1. Mutations in the rpoS gene are the major limiting factor for biofilm formation in Escherichia coli serotype O157:H7 clinical isolates

    USDA-ARS?s Scientific Manuscript database

    Background: Biofilm formation is a complex process that is highly regulated through a battery of transcriptional regulators, small regulatory RNAs, and environmental conditions. RpoS sigma factor along with MlrA protein directly regulate the expression of the curli key regulator CsgD. In most serot...

  2. Engineering hydrogen gas production from formate in a hyperthermophile by heterologous production of an 18-subunit membrane-bound complex.

    PubMed

    Lipscomb, Gina L; Schut, Gerrit J; Thorgersen, Michael P; Nixon, William J; Kelly, Robert M; Adams, Michael W W

    2014-01-31

    Biohydrogen gas has enormous potential as a source of reductant for the microbial production of biofuels, but its low solubility and poor gas mass transfer rates are limiting factors. These limitations could be circumvented by engineering biofuel production in microorganisms that are also capable of generating H2 from highly soluble chemicals such as formate, which can function as an electron donor. Herein, the model hyperthermophile, Pyrococcus furiosus, which grows optimally near 100 °C by fermenting sugars to produce H2, has been engineered to also efficiently convert formate to H2. Using a bacterial artificial chromosome vector, the 16.9-kb 18-gene cluster encoding the membrane-bound, respiratory formate hydrogen lyase complex of Thermococcus onnurineus was inserted into the P. furiosus chromosome and expressed as a functional unit. This enabled P. furiosus to utilize formate as well as sugars as an H2 source and to do so at both 80° and 95 °C, near the optimum growth temperature of the donor (T. onnurineus) and engineered host (P. furiosus), respectively. This accomplishment also demonstrates the versatility of P. furiosus for metabolic engineering applications.

  3. Engineering Hydrogen Gas Production from Formate in a Hyperthermophile by Heterologous Production of an 18-Subunit Membrane-bound Complex*

    PubMed Central

    Lipscomb, Gina L.; Schut, Gerrit J.; Thorgersen, Michael P.; Nixon, William J.; Kelly, Robert M.; Adams, Michael W. W.

    2014-01-01

    Biohydrogen gas has enormous potential as a source of reductant for the microbial production of biofuels, but its low solubility and poor gas mass transfer rates are limiting factors. These limitations could be circumvented by engineering biofuel production in microorganisms that are also capable of generating H2 from highly soluble chemicals such as formate, which can function as an electron donor. Herein, the model hyperthermophile, Pyrococcus furiosus, which grows optimally near 100 °C by fermenting sugars to produce H2, has been engineered to also efficiently convert formate to H2. Using a bacterial artificial chromosome vector, the 16.9-kb 18-gene cluster encoding the membrane-bound, respiratory formate hydrogen lyase complex of Thermococcus onnurineus was inserted into the P. furiosus chromosome and expressed as a functional unit. This enabled P. furiosus to utilize formate as well as sugars as an H2 source and to do so at both 80° and 95 °C, near the optimum growth temperature of the donor (T. onnurineus) and engineered host (P. furiosus), respectively. This accomplishment also demonstrates the versatility of P. furiosus for metabolic engineering applications. PMID:24318960

  4. Structure of soybean serine acetyltransferase and formation of the cysteine regulatory complex as a molecular chaperone

    USDA-ARS?s Scientific Manuscript database

    Serine acetyltransferase (SAT) catalyzes the limiting reaction in plant and microbial biosynthesis of cysteine. In addition to its enzymatic function, SAT forms a macromolecular complex with O-acetylserine sulfhydrylase (OASS). Formation of the cysteine regulatory complex (CRC) is a critical biochem...

  5. Effect of the ordered interfacial water layer in protein complex formation: A nonlocal electrostatic approach

    NASA Astrophysics Data System (ADS)

    Rubinstein, A.; Sabirianov, R. F.; Mei, W. N.; Namavar, F.; Khoynezhad, A.

    2010-08-01

    Using a nonlocal electrostatic approach that incorporates the short-range structure of the contacting media, we evaluated the electrostatic contribution to the energy of the complex formation of two model proteins. In this study, we have demonstrated that the existence of an ordered interfacial water layer at the protein-solvent interface reduces the charging energy of the proteins in the aqueous solvent, and consequently increases the electrostatic contribution to the protein binding (change in free energy upon the complex formation of two proteins). This is in contrast with the finding of the continuum electrostatic model, which suggests that electrostatic interactions are not strong enough to compensate for the unfavorable desolvation effects.

  6. Effect of the ordered interfacial water layer in protein complex formation: A nonlocal electrostatic approach.

    PubMed

    Rubinstein, A; Sabirianov, R F; Mei, W N; Namavar, F; Khoynezhad, A

    2010-08-01

    Using a nonlocal electrostatic approach that incorporates the short-range structure of the contacting media, we evaluated the electrostatic contribution to the energy of the complex formation of two model proteins. In this study, we have demonstrated that the existence of an ordered interfacial water layer at the protein-solvent interface reduces the charging energy of the proteins in the aqueous solvent, and consequently increases the electrostatic contribution to the protein binding (change in free energy upon the complex formation of two proteins). This is in contrast with the finding of the continuum electrostatic model, which suggests that electrostatic interactions are not strong enough to compensate for the unfavorable desolvation effects.

  7. Differential growth factor control of bone formation through osteoprogenitor differentiation.

    PubMed

    Chaudhary, L R; Hofmeister, A M; Hruska, K A

    2004-03-01

    The osteogenic factors bone morphogenetic protein (BMP-7), platelet-derived growth factor (PDGF)-BB, and fibroblast growth factor (FGF-2) regulate the recruitment of osteoprogenitor cells and their proliferation and differentiation into mature osteoblasts. However, their mechanisms of action on osteoprogenitor cell growth, differentiation, and bone mineralization remain unclear. Here, we tested the hypothesis that these osteogenic agents were capable of regulating osteoblast differentiation and bone formation in vitro. Normal human bone marrow stromal (HBMS) cells were treated with BMP-7 (40 ng ml(-1)), PDGF-BB (20 ng ml(-1)), FGF-2 (20 ng ml(-1)), or FGF-2 plus BMP-7 for 28 days in a serum-containing medium with 10 mM beta-glycerophosphate and 50 microg ml(-1) ascorbic acid. BMP-7 stimulated a morphological change to cuboidal-shaped cells, increased alkaline phosphatase (ALKP) activity, bone sialoprotein (BSP) gene expression, and alizarin red S positive nodule formation. Hydroxyapatite (HA) crystal deposition in the nodules was demonstrated by Fourier transform infrared (FTIR) spectroscopy only in BMP-7- and dexamethasone (DEX)-treated cells. DEX-treated cells appeared elongated and fibroblast-like compared to BMP-7-treated cells. FGF-2 did not stimulate ALKP, and cell morphology was dystrophic. PDGF-BB had little or no effect on ALKP activity and biomineralization. Alizarin Red S staining of cells and calcium assay indicated that BMP-7, DEX, and FGF-2 enhanced calcium mineral deposition, but FTIR spectroscopic analysis demonstrated no formation of HA similar to human bone in control, PDGF-BB-, and FGF-2-treated samples. Thus, FGF-2 stimulated amorphous octacalcium phosphate mineral deposition that failed to mature into HA. Interestingly, FGF-2 abrogated BMP-7-induced ALKP activity and HA formation. Results demonstrate that BMP-7 was competent as a sole factor in the differentiation of human bone marrow stromal cells to bone-forming osteoblasts confirmed by FTIR

  8. Electrocatalytic Oxidation of Formate by [Ni(P R 2 N R' 2 ) 2 (CH 3 CN)] 2+ Complexes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Galan, Brandon R.; Schöffel, Julia; Linehan, John C.

    2011-08-17

    New [Ni(P R 2N R` 2) 2+(CH 3CN)] 2+ complexes with R = Ph, R` = 4-MeOPh; R = Cy, R` = Ph and a mixed ligand [Ni(P R 2N R` 2)(P R`` 2N R` 2)] 2+ with R = Cy, R` = Ph, R`` = Ph have been synthesized and characterized by single crystal X-ray crystallography. These complexes are shown to be electrocatalysts for the oxidation of formate in solution to produce CO 2, protons, and electrons with rates which are first order in catalyst and in formate at formate concentrations below approximately 0.05 M. For the catalysts studied,more » maximum observed turnover frequencies vary from <1.1 s -1 to 12.5 s -1 at room temperature, which are the highest rates yet reported for formate oxidation by homogeneous catalysts. A mechanistic scheme is proposed which involves an initial nickel complex bound <1-OC(O)H followed by a rate limiting hydride transfer step. An acetate complex demonstrating the η 1-OC(O)CH 3 binding mode to nickel has also been synthesized and characterized by single crystal X-ray crystallography. The pendant amines have been demonstrated to be essential for this electrocatalytic activity as no activity toward formate was found for the similar [Ni(depe) 2][BF 4] 2+ (depe = diethylphosphinoethane) complex. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.« less

  9. Formation Mechanism of Oxide-Sulfide Complex Inclusions in High-Sulfur-Containing Steel Melts

    NASA Astrophysics Data System (ADS)

    Shin, Jae Hong; Park, Joo Hyun

    2018-02-01

    The [S] content in resulfurized steel is controlled in the range of 200 to 800 ppm to ensure good machinability and workability. It is well known that "MgAl2O4(spinel)+CaS" complex inclusions are formed in molten steel during the ladle refining process, and these cause nozzle clogging during continuous casting. Thus, in the present study, the "Refractory-Slag-Metal-Inclusions (ReSMI)" multiphase reaction model was employed in conjunction with experiments to investigate the influence of slag composition and [S] content in the steel on the formation of oxide-sulfide complex inclusions. The critical [S] and [Al] contents necessary for the precipitation of CaS in the CaO-Al2O3-MgO-SiO2 (CAMS) oxide inclusions were predicted from the composition of the liquid inclusions, as observed by scanning electron microscopy-electron dispersive spectrometry (SEM-EDS) and calculated using the ReSMI multiphase reaction model. The critical [S] content increases with increasing content of SiO2 in the slag at a given [Al] content. Formation mechanisms for spinel+CaS and spinel+MnS complex inclusions were also proposed.

  10. Cdt1p, through its interaction with Mcm6p, is required for the formation, nuclear accumulation and chromatin loading of the MCM complex.

    PubMed

    Wu, Rentian; Wang, Jiafeng; Liang, Chun

    2012-01-01

    Regulation of DNA replication initiation is essential for the faithful inheritance of genetic information. Replication initiation is a multi-step process involving many factors including ORC, Cdt1p, Mcm2-7p and other proteins that bind to replication origins to form a pre-replicative complex (pre-RC). As a prerequisite for pre-RC assembly, Cdt1p and the Mcm2-7p heterohexameric complex accumulate in the nucleus in G1 phase in an interdependent manner in budding yeast. However, the nature of this interdependence is not clear, nor is it known whether Cdt1p is required for the assembly of the MCM complex. In this study, we provide the first evidence that Cdt1p, through its interaction with Mcm6p with the C-terminal regions of the two proteins, is crucial for the formation of the MCM complex in both the cytoplasm and nucleoplasm. We demonstrate that disruption of the interaction between Cdt1p and Mcm6p prevents the formation of the MCM complex, excludes Mcm2-7p from the nucleus, and inhibits pre-RC assembly and DNA replication. Our findings suggest a function for Cdt1p in promoting the assembly of the MCM complex and maintaining its integrity by interacting with Mcm6p.

  11. A peroxynitrite complex of copper: formation from a copper-nitrosyl complex, transformation to nitrite and exogenous phenol oxidative coupling or nitration.

    PubMed

    Park, Ga Young; Deepalatha, Subramanian; Puiu, Simona C; Lee, Dong-Heon; Mondal, Biplab; Narducci Sarjeant, Amy A; del Rio, Diego; Pau, Monita Y M; Solomon, Edward I; Karlin, Kenneth D

    2009-11-01

    Reaction of nitrogen monoxide with a copper(I) complex possessing a tridentate alkylamine ligand gives a Cu(I)-(*NO) adduct, which when exposed to dioxygen generates a peroxynitrite (O=NOO(-))-Cu(II) species. This undergoes thermal transformation to produce a copper(II) nitrito (NO(2) (-)) complex and 0.5 mol equiv O(2). In the presence of a substituted phenol, the peroxynitrite complex effects oxidative coupling, whereas addition of chloride ion to dissociate the peroxynitrite moiety instead leads to phenol ortho nitration. Discussions include the structures (including electronic description) of the copper-nitrosyl and copper-peroxynitrite complexes and the formation of the latter, based on density functional theory calculations and accompanying spectroscopic data.

  12. Effect of ultrasonic waves on the water turbidity during the oxidation of phenol. Formation of (hydro)peroxo complexes.

    PubMed

    Villota, Natalia; Lomas, Jose M; Camarero, Luis M

    2017-11-01

    Analysis of the kinetics of aqueous phenol oxidation by a sono-Fenton process reveals that the via involving ortho-substituted intermediates prevails: catechol (25.0%), hydroquinone (7.7%) and resorcinol (0.6%). During the oxidation, water rapidly acquires color that reaches its maximum intensity at the maximum concentration of p-benzoquinone. Turbidity formation occurs at a slower rate. Oxidant dosage determines the nature of the intermediates, being trihydroxylated benzenes (pyrogallol, hydroxyhydroquinone) and muconic acid the main precursors causing turbidity. It is found that the concentration of iron species and ultrasonic waves affects the intensity of the turbidity. The pathway of (hydro)peroxo-iron(II) complexes formation is proposed. Operating with 20.0-27.8mgFe 2+ /kW rates leads to formation of (hydro)peroxo-iron(II) complexes, which induce high turbidity levels. These species would dissociate into ZZ-muconic acid and ferrous ions. Applying relationships around 13.9mgFe 2+ /kW, the formation of (hydro)peroxo-iron(III) complexes would occur, which could react with carboxylic acids (2,5-dioxo-3-hexenedioic acid). That reaction induces turbidity slower. This is due to the organic substrate reacting with two molecules of the (hydro)peroxo complex. Therefore, it is necessary to accelerate the iron regeneration, intensifying the ultrasonic irradiation. Afterwards, this complex would dissociate into maleic acid and ferric ions. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Hepatocyte Growth Factor Modulates MET Receptor Tyrosine Kinase and β-Catenin Functional Interactions to Enhance Synapse Formation

    PubMed Central

    Xie, Zhihui; Eagleson, Kathie L.

    2016-01-01

    MET, a pleiotropic receptor tyrosine kinase implicated in autism risk, influences multiple neurodevelopmental processes. There is a knowledge gap, however, in the molecular mechanism through which MET mediates developmental events related to disorder risk. In the neocortex, MET is expressed transiently during periods of peak dendritic outgrowth and synaptogenesis, with expression enriched at developing synapses, consistent with demonstrated roles in dendritic morphogenesis, modulation of spine volume, and excitatory synapse development. In a recent coimmunoprecipitation/mass spectrometry screen, β-catenin was identified as part of the MET interactome in developing neocortical synaptosomes. Here, we investigated the influence of the MET/β-catenin complex in mouse neocortical synaptogenesis. Western blot analysis confirms that MET and β-catenin coimmunoprecipitate, but N-cadherin is not associated with the MET complex. Following stimulation with hepatocyte growth factor (HGF), β-catenin is phosphorylated at tyrosine142 (Y142) and dissociates from MET, accompanied by an increase in β-catenin/N-cadherin and MET/synapsin 1 protein complexes. In neocortical neurons in vitro, proximity ligation assays confirmed the close proximity of these proteins. Moreover, in neurons transfected with synaptophysin-GFP, HGF stimulation increases the density of synaptophysin/bassoon (a presynaptic marker) and synaptophysin/PSD-95 (a postsynaptic marker) clusters. Mutation of β-catenin at Y142 disrupts the dissociation of the MET/β-catenin complex and prevents the increase in clusters in response to HGF. The data demonstrate a new mechanism for the modulation of synapse formation, whereby MET activation induces an alignment of presynaptic and postsynaptic elements that are necessary for assembly and formation of functional synapses by subsets of neocortical neurons that express MET/β-catenin complex. PMID:27595133

  14. Control of trichome formation in Arabidopsis by poplar single-repeat R3 MYB transcription factors

    PubMed Central

    Zhou, Limei; Zheng, Kaijie; Wang, Xiaoyu; Tian, Hainan; Wang, Xianling; Wang, Shucai

    2014-01-01

    In Arabidopsis, trichome formation is regulated by the interplay of R3 MYBs and several others transcription factors including the WD40-repeat protein TRANSPARENT TESTA GLABRA1 (TTG1), the R2R3 MYB transcription factor GLABRA1 (GL1), the bHLH transcription factor GLABRA3 (GL3) or ENHANCER OF GLABRA3 (EGL3), and the homeodomain protein GLABRA2 (GL2). R3 MYBs including TRICHOMELESS1 (TCL1), TCL2, TRYPTICHON (TRY), CAPRICE (CPC), ENHANCER OF TRY AND CPC1 (ETC1), ETC2 and ETC3 negatively regulate trichome formation by competing with GL1 for binding GL3 or EGL3, thus blocking the formation of TTG1–GL3/EGL3–GL1, an activator complex required for the activation of the trichome positive regulator gene GL2. However, it is largely unknown if R3 MYBs in other plant species especially woody plants have similar functions. By BLASTing the Populus trichocarpa protein database using the entire amino acid sequence of TCL1, an Arabidopsis R3 MYB transcription factor, we identified a total of eight R3 MYB transcription factor genes in poplar, namely P. trichocarpa TRICHOMELESS1 through 8 (PtrTCL1–PtrTCL8). The amino acid signature required for interacting with bHLH transcription factors and the amino acids required for cell-to-cell movement of R3 MYBs are not fully conserved in all PtrTCLs. When tested in Arabidopsis protoplasts, however, all PtrTCLs interacted with GL3. Expressing each of the eight PtrTCL genes in Arabidopsis resulted in either glabrous phenotypes or plants with reduced trichome numbers, and expression levels of GL2 in all transgenic plants tested were greatly reduced. Expression of PtrTCL1 under the control of TCL1 native promoter almost completely complemented the mutant phenotype of tcl. In contrast, expression of PtrTCL1 under the control of TRY native promoter in the try mutant, or under the control of CPC native promoter in the cpc mutant resulted in glabrous phenotypes, suggesting that PtrTCL1 functions similarly to TCL1, but not TRY and CPC. PMID

  15. STUDY USING A THREE-DIMENSIONAL SMOG FORMATION MODEL UNDER CONDITIONS OF COMPLEX FLOW

    EPA Science Inventory

    To clarify the photochemical smog formation mechanisms under conditions of complex flow, the SAI Urban Airshed Model was evaluated using a 1981 field observed data base. In the Tokyo Metropolitan Area higher O3 concentrations are usually observed near the shore in the morning. As...

  16. NADP-Specific Electron-Bifurcating [FeFe]-Hydrogenase in a Functional Complex with Formate Dehydrogenase in Clostridium autoethanogenum Grown on CO

    PubMed Central

    Wang, Shuning; Huang, Haiyan; Kahnt, Jörg; Mueller, Alexander P.; Köpke, Michael

    2013-01-01

    Flavin-based electron bifurcation is a recently discovered mechanism of coupling endergonic to exergonic redox reactions in the cytoplasm of anaerobic bacteria and archaea. Among the five electron-bifurcating enzyme complexes characterized to date, one is a heteromeric ferredoxin- and NAD-dependent [FeFe]-hydrogenase. We report here a novel electron-bifurcating [FeFe]-hydrogenase that is NADP rather than NAD specific and forms a complex with a formate dehydrogenase. The complex was found in high concentrations (6% of the cytoplasmic proteins) in the acetogenic Clostridium autoethanogenum autotrophically grown on CO, which was fermented to acetate, ethanol, and 2,3-butanediol. The purified complex was composed of seven different subunits. As predicted from the sequence of the encoding clustered genes (fdhA/hytA-E) and from chemical analyses, the 78.8-kDa subunit (FdhA) is a selenocysteine- and tungsten-containing formate dehydrogenase, the 65.5-kDa subunit (HytB) is an iron-sulfur flavin mononucleotide protein harboring the NADP binding site, the 51.4-kDa subunit (HytA) is the [FeFe]-hydrogenase proper, and the 18.1-kDa (HytC), 28.6-kDa (HytD), 19.9-kDa (HytE1), and 20.1-kDa (HytE2) subunits are iron-sulfur proteins. The complex catalyzed both the reversible coupled reduction of ferredoxin and NADP+ with H2 or formate and the reversible formation of H2 and CO2 from formate. We propose the complex to have two functions in vivo, namely, to normally catalyze CO2 reduction to formate with NADPH and reduced ferredoxin in the Wood-Ljungdahl pathway and to catalyze H2 formation from NADPH and reduced ferredoxin when these redox mediators get too reduced during unbalanced growth of C. autoethanogenum on CO (E0′ = −520 mV). PMID:23893107

  17. NADP-specific electron-bifurcating [FeFe]-hydrogenase in a functional complex with formate dehydrogenase in Clostridium autoethanogenum grown on CO.

    PubMed

    Wang, Shuning; Huang, Haiyan; Kahnt, Jörg; Mueller, Alexander P; Köpke, Michael; Thauer, Rudolf K

    2013-10-01

    Flavin-based electron bifurcation is a recently discovered mechanism of coupling endergonic to exergonic redox reactions in the cytoplasm of anaerobic bacteria and archaea. Among the five electron-bifurcating enzyme complexes characterized to date, one is a heteromeric ferredoxin- and NAD-dependent [FeFe]-hydrogenase. We report here a novel electron-bifurcating [FeFe]-hydrogenase that is NADP rather than NAD specific and forms a complex with a formate dehydrogenase. The complex was found in high concentrations (6% of the cytoplasmic proteins) in the acetogenic Clostridium autoethanogenum autotrophically grown on CO, which was fermented to acetate, ethanol, and 2,3-butanediol. The purified complex was composed of seven different subunits. As predicted from the sequence of the encoding clustered genes (fdhA/hytA-E) and from chemical analyses, the 78.8-kDa subunit (FdhA) is a selenocysteine- and tungsten-containing formate dehydrogenase, the 65.5-kDa subunit (HytB) is an iron-sulfur flavin mononucleotide protein harboring the NADP binding site, the 51.4-kDa subunit (HytA) is the [FeFe]-hydrogenase proper, and the 18.1-kDa (HytC), 28.6-kDa (HytD), 19.9-kDa (HytE1), and 20.1-kDa (HytE2) subunits are iron-sulfur proteins. The complex catalyzed both the reversible coupled reduction of ferredoxin and NADP(+) with H2 or formate and the reversible formation of H2 and CO2 from formate. We propose the complex to have two functions in vivo, namely, to normally catalyze CO2 reduction to formate with NADPH and reduced ferredoxin in the Wood-Ljungdahl pathway and to catalyze H2 formation from NADPH and reduced ferredoxin when these redox mediators get too reduced during unbalanced growth of C. autoethanogenum on CO (E0' = -520 mV).

  18. [Energetics of complex formation of the DNA hairpin structure d(GCGAAGC) with aromatic ligands].

    PubMed

    Kostiukov, V V

    2011-01-01

    The energy contributions of various physical interactions to the total Gibbs energy of complex formation of the biologically important DNA hairpin d(GCGAAGC) with aromatic antitumor antibiotics daunomycin and novantron and the mutagens ethidium and proflavine have been calculated. It has been shown that the relatively small value of the total energy of binding of the ligands to the hairpin is the sum of components great in absolute value and different in sign. The contributions of van der Waals interactions and both intra- and intermolecular hydrogen bonds and bonds with aqueous environment have been studied. According to the calculations, the hydrophobic and van der Waals components are energetically favorable in complex formation of the ligands with the DNA pairpin d(GCGAAGC), whereas the electrostatic (with consideration of hydrogen bonds) and entropic components are unfavorable.

  19. Studying the dynamics of SLP-76, Nck, and Vav1 multimolecular complex formation in live human cells with triple-color FRET.

    PubMed

    Pauker, Maor H; Hassan, Nirit; Noy, Elad; Reicher, Barak; Barda-Saad, Mira

    2012-04-24

    Protein-protein interactions regulate and control many cellular functions. A multimolecular complex consisting of the adaptor proteins SLP-76 (Src homology 2 domain-containing leukocyte protein of 76 kD), Nck, and the guanine nucleotide exchange factor Vav1 is recruited to the T cell side of the interface with an antigen-presenting cell during initial T cell activation. This complex is crucial for regulation of the actin machinery, antigen recognition, and signaling in T cells. We studied the interactions between these proteins as well as the dynamics of their recruitment into a complex that governs cytoskeletal reorganization. We developed a triple-color Förster resonance energy transfer (3FRET) system to observe the dynamics of the formation of this trimolecular signaling complex in live human T cells and to follow the three molecular interactions in parallel. Using the 3FRET system, we demonstrated that dimers of Nck and Vav1 were constitutively formed independently of both T cell activation and the association between SLP-76 and Nck. After T cell receptor stimulation, SLP-76 was phosphorylated, which enabled the binding of Nck. A point mutation in the proline-rich site of Vav1, which abolishes its binding to Nck, impaired actin rearrangement, suggesting that Nck-Vav1 dimers play a critical role in regulation of the actin machinery. We suggest that these findings revise the accepted model of the formation of a complex of SLP-76, Nck, and Vav1 and demonstrate the use of 3FRET as a tool to study signal transduction in live cells.

  20. Absorption spectrometric study of charge transfer complex formation between 4-acetamidophenol (paracetamol) and a series of quinones including Vitamin K 3

    NASA Astrophysics Data System (ADS)

    Saha, Avijit; Mukherjee, Asok K.

    2004-07-01

    The formation of charge transfer (CT) complexes of 4-acetamidophenol (commonly called 'paracetamol') and a series of quinones (including Vitamin K 3) has been studied spectrophotometrically in ethanol medium. The vertical ionisation potential of paracetamol and the degrees of charge transfer of the complexes in their ground state has been estimated from the trends in the charge transfer bands. The oscillator and transition dipole strengths of the complexes have been determined from the CT absorption spectra at 298 K. The complexes have been found by Job's method of continuous variation to have the uncommon 2:1 (paracetamol:quinone) stoichiometry in each case. The enthalpies and entropies of formation of the complexes have been obtained by determining their formation constants at five different temperatures.

  1. Spectrophotometric Study of the Complex Formation of Anionic Chelates of Cobalt(II) with Monotetrazolium Cations

    NASA Astrophysics Data System (ADS)

    Divarova, V. V.; Stojnova, K. T.; Racheva, P. V.; Lekova, V. D.

    2017-05-01

    The complex formation and extraction of anionic chelates of Co(II)-4-(2-thiazolylazo)resorcinol (TAR) with cations of monotetrazolium salts (TS) — (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and 3-(2-naphthyl)-2,5-diphenyl-2H-tetrazolium chloride (TV) — in the liquid-liquid extraction system Co(II)-TAR-TS-H2O-CHCl3 were studied by spectrophotometric methods. The optimum conditions for the extraction of Co(II) were found. The molar ratio of the components and the form of the anionic chelates of Co(II) in the extracted compounds were determined by independent methods. The association process in the aqueous phase and the extraction process were investigated and quantitatively characterized. The following key constants were calculated: association constant, distribution constant, extraction constant, and recovery factor. The validity of the Beer's law was checked, and some analytical characteristics were calculated. Based on the obtained results and the lower price of the monotetrazolium salt MTT compared with that of TV, the ion-associated complex of Co(II)-TAR-MTT can be implemented for determination of cobalt(II) traces in alloys and biological, medical, and pharmaceutical samples.

  2. Membrane transport of WAVE2 and lamellipodia formation require Pak1 that mediates phosphorylation and recruitment of stathmin/Op18 to Pak1-WAVE2-kinesin complex.

    PubMed

    Takahashi, Kazuhide; Suzuki, Katsuo

    2009-05-01

    Membrane transport of WAVE2 that leads to lamellipodia formation requires a small GTPase Rac1, the motor protein kinesin, and microtubules. Here we explore the possibility of whether the Rac1-dependent and kinesin-mediated WAVE2 transport along microtubules is regulated by a p21-activated kinase Pak as a downstream effector of Rac1. We find that Pak1 constitutively binds to WAVE2 and is transported with WAVE2 to the leading edge by stimulation with hepatocyte growth factor (HGF). Concomitantly, phosphorylation of tubulin-bound stathmin/Op18 at serine 25 (Ser25) and Ser38, microtubule growth, and stathmin/Op18 binding to kinesin-WAVE2 complex were induced. The HGF-induced WAVE2 transport, lamellipodia formation, stathmin/Op18 phosphorylation at Ser38 and binding to kinesin-WAVE2 complex, but not stathmin/Op18 phosphorylation at Ser25 and microtubule growth, were abrogated by Pak1 inhibitor IPA-3 and Pak1 depletion with small interfering RNA (siRNA). Moreover, stathmin/Op18 depletion with siRNA caused significant inhibition of HGF-induced WAVE2 transport and lamellipodia formation, with HGF-independent promotion of microtubule growth. Collectively, it is suggested that Pak1 plays a critical role in HGF-induced WAVE2 transport and lamellipodia formation by directing Pak1-WAVE2-kinesin complex toward the ends of growing microtubules through phosphorylation and recruitment of tubulin-bound stathmin/Op18 to the complex.

  3. Influence of structural features of carrageenan on the formation of polyelectrolyte complexes with chitosan.

    PubMed

    Volod'ko, A V; Davydova, V N; Glazunov, V P; Likhatskaya, G N; Yermak, I M

    2016-03-01

    The polyelectrolyte complexes (PEC) of carrageenans (CG)-κ-, κ/β-, λ-and x-CG with chitosan were obtained. The formation of PEC was detected by Fourier-transform infrared (FTIR) spectroscopy and by centrifugation in a Percoll gradient. The influence of the structural peculiarities of CG on its interaction with chitosan was studied. The results of centrifugation showed that x-CG with a high degree of sulphation (SD) was completely bound to chitosan, unlike low SD κ-CG and κ/β-CG. Binding constant values showed there was a high affinity of CG for chitosan. CG with flexible macromolecule conformation and high SD exhibited the greatest binding affinity for chitosan. The full-atomic 3D-structures of the PEC κ-CG: chitosan in solution have been obtained by the experiments in silico for the first time. The amino groups of chitosan make the largest contribution to the energy of the complex formation by means of hydrogen and ionic bonds. The most probable complexes have stoichiometries of 1:1 and 1:1.5. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Formation of Mixed-Ligand Complexes of Metals(II) with Monoamine Complexones and Amino Acids in Solution

    NASA Astrophysics Data System (ADS)

    Pyreu, D. F.; Gridchin, S. N.

    2018-05-01

    The formation of mixed-ligand complexes in the M(II)-Nta, Ida-L (M = Cu(II), Ni, Zn, Co(II), L = Ser, Thr, Asp, Arg, Asn) systems, where Ida and Nta are the residues of iminodiacetic and nitrilotriacetic acids, respectively, is studied using pH measurements, calorimetry and spectrophotometry. The thermodynamic parameters (log K, Δr G 0, Δr H, Δr S) of their formation at 298.15 K and ionic strength I = 0.5 (KNO3) are determined. The most likely scenario of amino acid residue coordination in the composition of mixed complexes is discussed.

  5. HTLV-1 Tax Induces Formation of the Active Macromolecular IKK Complex by Generating Lys63- and Met1-Linked Hybrid Polyubiquitin Chains.

    PubMed

    Shibata, Yuri; Tokunaga, Fuminori; Goto, Eiji; Komatsu, Ginga; Gohda, Jin; Saeki, Yasushi; Tanaka, Keiji; Takahashi, Hirotaka; Sawasaki, Tatsuya; Inoue, Satoshi; Oshiumi, Hiroyuki; Seya, Tsukasa; Nakano, Hiroyasu; Tanaka, Yuetsu; Iwai, Kazuhiro; Inoue, Jun-Ichiro

    2017-01-01

    The Tax protein of human T-cell leukemia virus type 1 (HTLV-1) is crucial for the development of adult T-cell leukemia (ATL), a highly malignant CD4+ T cell neoplasm. Among the multiple aberrant Tax-induced effects on cellular processes, persistent activation of transcription factor NF-κB, which is activated only transiently upon physiological stimulation, is essential for leukemogenesis. We and others have shown that Tax induces activation of the IκB kinase (IKK) complex, which is a critical step in NF-κB activation, by generating Lys63-linked polyubiquitin chains. However, the molecular mechanism underlying Tax-induced IKK activation is controversial and not fully understood. Here, we demonstrate that Tax recruits linear (Met1-linked) ubiquitin chain assembly complex (LUBAC) to the IKK complex and that Tax fails to induce IKK activation in cells that lack LUBAC activity. Mass spectrometric analyses revealed that both Lys63-linked and Met1-linked polyubiquitin chains are associated with the IKK complex. Furthermore, treatment of the IKK-associated polyubiquitin chains with Met1-linked-chain-specific deubiquitinase (OTULIN) resulted in the reduction of high molecular weight polyubiquitin chains and the generation of short Lys63-linked ubiquitin chains, indicating that Tax can induce the generation of Lys63- and Met1-linked hybrid polyubiquitin chains. We also demonstrate that Tax induces formation of the active macromolecular IKK complex and that the blocking of Tax-induced polyubiquitin chain synthesis inhibited formation of the macromolecular complex. Taken together, these results lead us to propose a novel model in which the hybrid-chain-dependent oligomerization of the IKK complex triggered by Tax leads to trans-autophosphorylation-mediated IKK activation.

  6. Effect of Ramadan fasting on urinary risk factors for calculus formation.

    PubMed

    Miladipour, Amir Hossein; Shakhssalim, Nasser; Parvin, Mahmoud; Azadvari, Mohaddeseh

    2012-01-01

    Even though dehydration could aggravate formation of urinary calculi, the effects of fluid and food restriction on calculus formation is not thoroughly defined. The purpose of this study is to evaluate the effects of fluid and food restriction in Ramadan fasting on urinary factors in kidney and urinary calculus formation. Fifty-seven men aged 30 to 55 years old, including 37 recurrent calcium calculus formers and 20 with no history of kidney calculi were evaluated for blood tests, ultrasonography investigations, urinalysis, urine culture, and also 24-hour urine collection test. Metabolites including calcium, oxalate, citrate, uric acid, magnesium, phosphate, potassium, sodium, and creatinine were measured before and during Ramadan fasting. The values of calculus-precipitating solutes as well as inhibitory factors were documented thoroughly. Total excretion of calcium, phosphate, and magnesium in 24-hour urine and also urine volume during fasting were significantly lower than those in the nonfasting period. Urine concentration of calcium during fasting was significantly lower than nonfasting (P < .001). Urine concentrations of uric acid, citrate, phosphate, sodium, and potassium during fasting were significantly higher than nonfasting. Uric acid supersaturation was accentuated, and calcium phosphate supersaturation was decreased significantly during fasting. There was no significant increase in calcium oxalate supersaturation during the fasting period. Fasting during Ramadan has different effects on total excretion and concentrations of urinary precipitate and inhibitory factors contributing to calculus formation. We did not find enough evidence in favor of increased risks of calculus formation during Ramadan fasting.

  7. Investigation of Model Sunscreen Formulations Comparing the Sun Protection Factor, the Universal Sun Protection Factor and the Radical Formation Ratio.

    PubMed

    Syring, Felicia; Weigmann, Hans-Jürgen; Schanzer, Sabine; Meinke, Martina C; Knorr, Fanny; Lademann, Jürgen

    2016-01-01

    In view of globally rising skin cancer rates and harmful effects exerted by sunlight throughout the ultraviolet, visible and infrared ranges, an objective, safe and comprehensive method for determining sunscreen efficacy is required in order to warrant safe sun exposure. In this study, the influence of characteristic active ingredients (chemical filters, physical filters and antioxidants) on different sunscreen indicators, including the universal sun protection factor and the radical formation ratio, was determined and compared to their influence on sun protection factor values. Spectroscopic universal sun protection factor measurements were conducted ex vivo by analyzing tape strips taken from human skin, and radical formation ratio determination was performed via electron paramagnetic resonance spectroscopy using porcine ear skin ex vivo. The sun protection factor determination was conducted according to ISO standards (ISO 24444:2010). It was shown that chemical filters provide a protective effect which was measurable by all methods examined (spectroscopy, electron paramagnetic resonance spectroscopy and erythema formation). Physical filters, when used as single active ingredients, increased protective values in universal sun protection factor and sun protection factor measurements but exhibited no significant effect on universal sun protection factor measurements when used in combination with chemical filters or antioxidants. Antioxidants were shown to increase sun protection factor values. Radical formation ratio values were shown to be influenced merely by chemical filters, leading to the conclusion that the universal sun protection factor is the most suitable efficacy indicator for the ultraviolet range. © 2015 S. Karger AG, Basel.

  8. Factors affecting catalysis of copper corrosion products in NDMA formation from DMA in simulated premise plumbing.

    PubMed

    Zhang, Hong; Andrews, Susan A

    2013-11-01

    This study investigated the effects of corrosion products of copper, a metal commonly employed in household plumbing systems, on N-nitrosodimethylamine (NDMA) formation from a known NDMA precursor, dimethylamine (DMA). Copper-catalyzed NDMA formation increased with increasing copper concentrations, DMA concentrations, alkalinity and hardness, but decreased with increasing natural organic matter (NOM) concentration. pH influenced the speciation of chloramine and the interactions of copper with DMA. The transformation of monochloramine (NH2Cl) to dichloramine and complexation of copper with DMA were involved in elevating the formation of NDMA by copper at pH 7.0. The inhibiting effect of NOM on copper catalysis was attributed to the rapid consumption of NH2Cl by NOM and/or the competitive complexation of NOM with copper to limit the formation of DMA-copper complexes. Hardness ions, as represented by Ca(2+), also competed with copper for binding sites on NOM, thereby weakening the inhibitory effect of NOM on NDMA formation. Common copper corrosion products also participated in these reactions but in different ways. Aqueous copper released from malachite [Cu2CO3(OH)2] was shown to promote NDMA formation while NDMA formation decreased in the presence of CuO, most likely due to the adsorption of DMA. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Significance of the DNA-Histone Complex Level as a Predictor of Major Adverse Cardiovascular Events in Hemodialysis Patients: The Effect of Uremic Toxin on DNA-Histone Complex Formation.

    PubMed

    Jeong, Jong Cheol; Kim, Ji-Eun; Gu, Ja-Yoon; Yoo, Hyun Ju; Ryu, Ji Won; Kim, Dong Ki; Joo, Kwon Wook; Kim, Hyun Kyung

    2016-01-01

    Neutrophils can release the DNA-histone complex into circulation following exposure to inflammatory stimuli. This prospective study investigated whether the DNA-histone complex and other biomarkers could predict major cardiovascular adverse events (MACEs) in hemodialysis (HD) patients. The levels of circulating DNA-histone complexes, cell-free DNA, interleukin (IL)-6, and neutrophil elastase were measured in 60 HD patients and 28 healthy controls. MACE was assessed at 24 months. Uremic toxin-induced neutrophil released contents were measured in vitro. Compared with controls, HD patients showed higher levels of DNA-histone complexes and IL-6. The DNA-histone complex level was inversely associated with the Kt/V. In a multivariable Cox analysis, the high level of DNA-histone complexes was a significant independent predictor of MACE. The uremic toxins induced DNA-histone complex formation in normal neutrophils in vitro. The DNA-histone complex is a potentially useful marker to predict MACE in HD patients. Uremic toxins induced DNA-histone complex formation in vitro. © 2015 S. Karger AG, Basel.

  10. Formation of novel transition metal hydride complexes with ninefold hydrogen coordination

    PubMed Central

    Takagi, Shigeyuki; Iijima, Yuki; Sato, Toyoto; Saitoh, Hiroyuki; Ikeda, Kazutaka; Otomo, Toshiya; Miwa, Kazutoshi; Ikeshoji, Tamio; Orimo, Shin-ichi

    2017-01-01

    Ninefold coordination of hydrogen is very rare, and has been observed in two different hydride complexes comprising rhenium and technetium. Herein, based on a theoretical/experimental approach, we present evidence for the formation of ninefold H- coordination hydride complexes of molybdenum ([MoH9]3−), tungsten ([WH9]3−), niobium ([NbH9]4−) and tantalum ([TaH9]4−) in novel complex transition-metal hydrides, Li5MoH11, Li5WH11, Li6NbH11 and Li6TaH11, respectively. All of the synthesized materials are insulated with band gaps of approximately 4 eV, but contain a sufficient amount of hydrogen to cause the H 1s-derived states to reach the Fermi level. Such hydrogen-rich materials might be of interest for high-critical-temperature superconductivity if the gaps close under compression. Furthermore, the hydride complexes exhibit significant rotational motions associated with anharmonic librations at room temperature, which are often discussed in relation to the translational diffusion of cations in alkali-metal dodecahydro-closo-dodecaborates and strongly point to the emergence of a fast lithium conduction even at room temperature. PMID:28287143

  11. Complex conductivity response to microbial growth and biofilm formation on phenanthrene spiked medium

    NASA Astrophysics Data System (ADS)

    Albrecht, Remy; Gourry, Jean Christophe; Simonnot, Marie-Odile; Leyval, Corinne

    2011-11-01

    Several laboratory studies have recently demonstrated the utility of geophysical methods for the investigation of microbial-induced changes over contaminated sites. However, it remains difficult to distinguish the effects due to the new physical properties imparted by microbial processes, to bacterial growth, or to the development of bacterial biofilm. We chose to study the influence of biofilm formation on geophysical response using complex conductivity measurements (0.1-1000 Hz) in phenanthrene-contaminated media. Biotic assays were conducted with two phenanthrene (PHE) degrading bacterial strains: Burkholderia sp (NAH1), which produced biofilm and Stenophomonas maltophilia (MATE10), which did not, and an abiotic control. Results showed that bacterial densities for NAH1 and MATE10 strains continuously increased at the same rate during the experiment. However, the complex conductivity signature showed noticeable differences between the two bacteria, with a phase shift of 50 mrad at 4 Hz for NAH1, which produced biofilm. Biofilm volume was quantified by Scanning Confocal Laser Microscopy (SCLM). Significant correlations were established between phase shift decrease and biofilm volume for NAH1 assays. Results suggest that complex conductivity measurements, specifically phase shift, can be a useful indicator of biofilm formation inside the overall signal of microbial activity on contaminated sites.

  12. Nup155 regulates nuclear envelope and nuclear pore complex formation in nematodes and vertebrates

    PubMed Central

    Franz, Cerstin; Askjaer, Peter; Antonin, Wolfram; Iglesias, Carmen López; Haselmann, Uta; Schelder, Malgorzata; de Marco, Ario; Wilm, Matthias; Antony, Claude; Mattaj, Iain W

    2005-01-01

    Nuclear envelope (NE) formation during cell division in multicellular organisms is a central yet poorly understood biological process. We report that the conserved nucleoporin Nup155 has an essential function in NE formation in Caenorhabditis elegans embryos and in Xenopus laevis egg extracts. In vivo depletion of Nup155 led to failure of nuclear lamina formation and defects in chromosome segregation at anaphase. Nup155 depletion inhibited accumulation of nucleoporins at the nuclear periphery, including those recruited to chromatin early in NE formation. Electron microscopy analysis revealed that Nup155 is also required for the formation of a continuous nuclear membrane in vivo and in vitro. Time-course experiments indicated that Nup155 is recruited to chromatin at the time of NE sealing, suggesting that nuclear pore complex assembly has to progress to a relatively late stage before NE membrane assembly occurs. PMID:16193066

  13. TGF-{beta} signals the formation of a unique NF1/Smad4-dependent transcription repressor-complex in human diploid fibroblasts

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Luciakova, Katarina, E-mail: katarina.luciakova@savba.sk; Kollarovic, Gabriel; Kretova, Miroslava

    2011-08-05

    Highlights: {yields} TGF-{beta} induces the formation of unique nuclear NF1/Smad4 complexes that repress expression of the ANT-2 gene. {yields} Repression is mediated through an NF1-dependent repressor element in the promoter. {yields} The formation of NF1/Smad4 complexes and the repression of ANT2 are prevented by inhibitors of p38 kinase and TGF-{beta} RI. {yields} NF1/Smad complexes implicate novel role for NF1 and Smad proteins in the regulation of growth. -- Abstract: We earlier reported the formation of a unique nuclear NF1/Smad complex in serum-restricted fibroblasts that acts as an NF1-dependent repressor of the human adenine nucleotide translocase-2 gene (ANT2) [K. Luciakova, G.more » Kollarovic, P. Barath, B.D. Nelson, Growth-dependent repression of human adenine nucleotide translocator-2 (ANT2) transcription: evidence for the participation of Smad and Sp family proteins in the NF1-dependent repressor complex, Biochem. J. 412 (2008) 123-130]. In the present study, we show that TGF-{beta}, like serum-restriction: (a) induces the formation of NF1/Smad repressor complexes, (b) increases binding of the complexes to the repressor elements (Go elements) in the ANT2 promoter, and (c) inhibits ANT2 expression. Repression of ANT2 by TGF-{beta} is eliminated by mutating the NF1 binding sites in the Go repressor elements. All of the above responses to TGF-{beta} are prevented by inhibitors of TGF-{beta} RI and MAPK p38. These inhibitors also prevent NF1/Smad4 repressor complex formation and repression of ANT2 expression in serum-restricted cells, suggesting that similar signaling pathways are initiated by TGF-{beta} and serum-restriction. The present finding that NF1/Smad4 repressor complexes are formed through TGF-{beta} signaling pathways suggests a new, but much broader, role for these complexes in the initiation or maintenance of the growth-inhibited state.« less

  14. The prostaglandin receptor EP2 activates multiple signaling pathways and β-arrestin1 complex formation during mouse skin papilloma development

    PubMed Central

    Chun, Kyung-Soo; Lao, Huei-Chen; Trempus, Carol S.; Okada, Manabu; Langenbach, Robert

    2009-01-01

    Prostaglandin E2 (PGE2) is elevated in many tumor types, but PGE2's contributions to tumor growth are largely unknown. To investigate PGE2's roles, the contributions of one of its receptors, EP2, were studied using the mouse skin initiation/promotion model. Initial studies indicated that protein kinase A (PKA), epidermal growth factor receptor (EGFR) and several effectors—cyclic adenosine 3′,5′-monophosphate response element-binding protein (CREB), H-Ras, Src, protein kinase B (AKT) and extracellular signal-regulated kinase (ERK)1/2—were activated in 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted papillomas and that PKA and EGFR inhibition (H89 and AG1478, respectively) decreased papilloma formation. EP2's contributions to the activation of these pathways and papilloma development were determined by inhibiting endogenous TPA-induced PGE2 production with indomethacin (Indo) and concomitantly treating with the EP2 agonist, CAY10399 (CAY). CAY treatment restored papilloma formation in TPA/Indo-treated mice and increased cyclic adenosine 3′,5′-monophosphate and PKA activation as measured by p-CREB formation. CAY treatment also increased EGFR and Src activation and their inhibition by AG1478 and PP2 indicated that Src was upstream of EGFR. CAY also increased H-Ras, ERK1/2 and AKT activation, and AG1478 decreased their activation indicating EGFR being upstream. Supporting EP2's contribution, EP2−/− mice exhibited 65% fewer papillomas and reduced Src, EGFR, H-Ras, AKT and ERK1/2 activation. G protein-coupled receptor (GPCR) activation of EGFR has been reported to involve Src's activation via a GPCR–β-arrestin–Src complex. Indeed, immunoprecipitation of β-arrestin1 or p-Src indicated the presence of an EP2–β-arrestin1–p-Src complex in papillomas. The data indicated that EP2 contributed to tumor formation via activation of PKA and EGFR and that EP2 formed a complex with β-arrestin1 and Src that contributed to signaling and/or EP2

  15. Myeloid Leukemia Factor Acts in a Chaperone Complex to Regulate Transcription Factor Stability and Gene Expression.

    PubMed

    Dyer, Jamie O; Dutta, Arnob; Gogol, Madelaine; Weake, Vikki M; Dialynas, George; Wu, Xilan; Seidel, Christopher; Zhang, Ying; Florens, Laurence; Washburn, Michael P; Abmayr, Susan M; Workman, Jerry L

    2017-06-30

    Mutations that affect myelodysplasia/myeloid leukemia factor (MLF) proteins are associated with leukemia and several other cancers. However, with no strong homology to other proteins of known function, the role of MLF proteins in the cell has remained elusive. Here, we describe a proteomics approach that identifies MLF as a member of a nuclear chaperone complex containing a DnaJ protein, BCL2-associated anthanogene 2, and Hsc70. This complex associates with chromatin and regulates the expression of target genes. The MLF complex is bound to sites of nucleosome depletion and sites containing active chromatin marks (e.g., H3K4me3 and H3K4me1). Hence, MLF binding is enriched at promoters and enhancers. Additionally, the MLF-chaperone complex functions to regulate transcription factor stability, including the RUNX transcription factor involved in hematopoiesis. Although Hsc70 and other co-chaperones have been shown to play a role in nuclear translocation of a variety of proteins including transcription factors, our findings suggest that MLF and the associated co-chaperones play a direct role in modulating gene transcription. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. The Catabolite Repressor Protein-Cyclic AMP Complex Regulates csgD and Biofilm Formation in Uropathogenic Escherichia coli.

    PubMed

    Hufnagel, David A; Evans, Margery L; Greene, Sarah E; Pinkner, Jerome S; Hultgren, Scott J; Chapman, Matthew R

    2016-12-15

    The extracellular matrix protects Escherichia coli from immune cells, oxidative stress, predation, and other environmental stresses. Production of the E. coli extracellular matrix is regulated by transcription factors that are tuned to environmental conditions. The biofilm master regulator protein CsgD upregulates curli and cellulose, the two major polymers in the extracellular matrix of uropathogenic E. coli (UPEC) biofilms. We found that cyclic AMP (cAMP) regulates curli, cellulose, and UPEC biofilms through csgD The alarmone cAMP is produced by adenylate cyclase (CyaA), and deletion of cyaA resulted in reduced extracellular matrix production and biofilm formation. The catabolite repressor protein (CRP) positively regulated csgD transcription, leading to curli and cellulose production in the UPEC isolate, UTI89. Glucose, a known inhibitor of CyaA activity, blocked extracellular matrix formation when added to the growth medium. The mutant strains ΔcyaA and Δcrp did not produce rugose biofilms, pellicles, curli, cellulose, or CsgD. Three putative CRP binding sites were identified within the csgD-csgB intergenic region, and purified CRP could gel shift the csgD-csgB intergenic region. Additionally, we found that CRP binded upstream of kpsMT, which encodes machinery for K1 capsule production. Together our work shows that cAMP and CRP influence E. coli biofilms through transcriptional regulation of csgD IMPORTANCE The catabolite repressor protein (CRP)-cyclic AMP (cAMP) complex influences the transcription of ∼7% of genes on the Escherichia coli chromosome (D. Zheng, C. Constantinidou, J. L. Hobman, and S. D. Minchin, Nucleic Acids Res 32:5874-5893, 2004, https://dx.doi.org/10.1093/nar/gkh908). Glucose inhibits E. coli biofilm formation, and ΔcyaA and Δcrp mutants show impaired biofilm formation (D. W. Jackson, J.W. Simecka, and T. Romeo, J Bacteriol 184:3406-3410, 2002, https://dx.doi.org/10.1128/JB.184.12.3406-3410.2002). We determined that the c

  17. Unique behaviour of dinitrogen-bridged dimolybdenum complexes bearing pincer ligand towards catalytic formation of ammonia.

    PubMed

    Tanaka, Hiromasa; Arashiba, Kazuya; Kuriyama, Shogo; Sasada, Akira; Nakajima, Kazunari; Yoshizawa, Kazunari; Nishibayashi, Yoshiaki

    2014-04-28

    It is vital to design effective nitrogen fixation systems that operate under mild conditions, and to this end we recently reported an example of the catalytic formation of ammonia using a dinitrogen-bridged dimolybdenum complex bearing a pincer ligand, where up to twenty three equivalents of ammonia were produced based on the catalyst. Here we study the origin of the catalytic behaviour of the dinitrogen-bridged dimolybdenum complex bearing the pincer ligand with density functional theory calculations, based on stoichiometric and catalytic formation of ammonia from molecular dinitrogen under ambient conditions. Comparison of di- and mono-molybdenum systems shows that the dinitrogen-bridged dimolybdenum core structure plays a critical role in the protonation of the coordinated molecular dinitrogen in the catalytic cycle.

  18. Scope Complexity Options Risks Excursions (SCORE) Factor Mathematical Description.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gearhart, Jared Lee; Samberson, Jonell Nicole; Shettigar, Subhasini

    The purpose of the Scope, Complexity, Options, Risks, Excursions (SCORE) model is to estimate the relative complexity of design variants of future warhead options, resulting in scores. SCORE factors extend this capability by providing estimates of complexity relative to a base system (i.e., all design options are normalized to one weapon system). First, a clearly defined set of scope elements for a warhead option is established. The complexity of each scope element is estimated by Subject Matter Experts (SMEs), including a level of uncertainty, relative to a specific reference system. When determining factors, complexity estimates for a scope element canmore » be directly tied to the base system or chained together via comparable scope elements in a string of reference systems that ends with the base system. The SCORE analysis process is a growing multi-organizational Nuclear Security Enterprise (NSE) effort, under the management of the NA-12 led Enterprise Modeling and Analysis Consortium (EMAC). Historically, it has provided the data elicitation, integration, and computation needed to support the out-year Life Extension Program (LEP) cost estimates included in the Stockpile Stewardship Management Plan (SSMP).« less

  19. Functional properties of an isolated. cap alpha beta. heterodimeric human placenta insulin-like growth factor 1 receptor complex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feltz, S.M.; Swanson, M.L.; Wemmie, J.A.

    1988-05-03

    Treatment of human placenta membranes at pH 8.5 in the presence of 2.0 mM dithiothreitol (DTT) for 5 min, followed by the simultaneous removal of the DTT and pH adjustment of pH 7.6, resulted in the formation of a functional ..cap alpha beta.. heterodimeric insulin-like growth factor 1 (IGF-1) receptor complex from the native ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric disulfide-linked state. The membrane-bound ..cap alpha beta.. heterodimeric complex displayed similar curvilinear /sup 125/I-IGF-1 equilibrium binding compared to the ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric complex. /sup 125/I-IGF-1 binding to both the isolated ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric and ..cap alpha beta..more » heterodimeric complexes demonstrated a marked straightening of the Scatchard plots, compared to the placenta membrane-bound IGF-1 receptors, with a 2-fold increase in the high-affinity binding component. IGF-1 stimulation of IGF-1 receptor autophosphorylation indicated that the ligand-dependent activation of ..cap alpha beta.. heterodimeric protein kinase activity occurred concomitant with the reassociation into a covalent ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric state. These data demonstrate that (i) a combination of alkaline pH and DTT treatment of human placenta membranes results in the formation of an ..cap alpha beta.. heterodimeric IGF-1 receptor complex, (ii) unlike the insulin receptor, high-affinity homogeneous IGF-1 binding occurs in both the ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric and ..cap alpha beta.. heterodimeric complexes, and (iii) IGF-1-dependent autophosphorylation of the ..cap alpha beta.. heterodimeric IGF-1 receptor complex correlates wit an IGF-1 dependent covalent reassociation into an ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric disulfide-linked state.« less

  20. A Photoluminescence Study of the Changes Induced in the Zinc White Pigment by Formation of Zinc Complexes

    PubMed Central

    Artesani, Alessia; Gherardi, Francesca; Nevin, Austin; Valentini, Gianluca; Comelli, Daniela

    2017-01-01

    It is known that oil paintings containing zinc white are subject to rapid degradation. This is caused by the interaction between the active groups of binder and the metal ions of the pigment, which gives rise to the formation of new zinc complexes (metal soaps). Ongoing studies on zinc white paints have been limited to the chemical mechanisms that lead to the formation of zinc complexes. On the contrary, little is known of the photo-physical changes induced in the zinc oxide crystal structure following this interaction. Time-resolved photoluminescence spectroscopy has been applied to follow modifications in the luminescent zinc white pigment when mixed with binder. Significant changes in trap state photoluminescence emissions have been detected: the enhancement of a blue emission combined with a change of the decay kinetic of the well-known green emission. Complementary data from molecular analysis of paints using Fourier transform infrared spectroscopy confirms the formation of zinc carboxylates and corroborates the mechanism for zinc complexes formation. We support the hypothesis that zinc ions migrate into binder creating novel vacancies, affecting the photoluminescence intensity and lifetime properties of zinc oxide. Here, we further demonstrate the advantages of a time-resolved photoluminescence approach for studying defects in semiconductor pigments. PMID:28772700

  1. The FRIGIDA Complex Activates Transcription of FLC, a Strong Flowering Repressor in Arabidopsis, by Recruiting Chromatin Modification Factors[C][W

    PubMed Central

    Choi, Kyuha; Kim, Juhyun; Hwang, Hyun-Ju; Kim, Sanghee; Park, Chulmin; Kim, Sang Yeol; Lee, Ilha

    2011-01-01

    The flowering of Arabidopsis thaliana winter annuals is delayed until the subsequent spring by the strong floral repressor FLOWERING LOCUS C (FLC). FRIGIDA (FRI) activates the transcription of FLC, but the molecular mechanism remains elusive. The fri mutation causes early flowering with reduced FLC expression similar to frl1, fes1, suf4, and flx, which are mutants of FLC-specific regulators. Here, we report that FRI acts as a scaffold protein interacting with FRL1, FES1, SUF4, and FLX to form a transcription activator complex (FRI-C). Each component of FRI-C has a specialized function. SUF4 binds to a cis-element of the FLC promoter, FLX and FES1 have transcriptional activation potential, and FRL1 and FES1 stabilize the complex. FRI-C recruits a general transcription factor, a TAF14 homolog, and chromatin modification factors, the SWR1 complex and SET2 homolog. Complex formation was confirmed by the immunoprecipitation of FRI-associated proteins followed by mass spectrometric analysis. Our results provide insight into how a specific transcription activator recruits chromatin modifiers to regulate a key flowering gene. PMID:21282526

  2. Young stellar population and ongoing star formation in the H II complex Sh2-252

    NASA Astrophysics Data System (ADS)

    Jose, Jessy; Pandey, A. K.; Samal, M. R.; Ojha, D. K.; Ogura, K.; Kim, J. S.; Kobayashi, N.; Goyal, A.; Chauhan, N.; Eswaraiah, C.

    2013-07-01

    In this paper, an extensive survey of the star-forming complex Sh2-252 has been undertaken with an aim to explore its hidden young stellar population as well as to understand the structure and star formation history for the first time. This complex is composed of five prominent embedded clusters associated with the subregions A, C, E, NGC 2175s and Teu 136. We used Two Micron All Sky Survey-near-infrared and Spitzer-Infrared Array Camera, Multiband Imaging Photometer for Spitzer photometry to identify and classify the young stellar objects (YSOs) by their infrared (IR) excess emission. Using the IR colour-colour criteria, we identified 577 YSOs, of which, 163 are Class I, 400 are Class II and 14 are transition disc YSOs, suggesting a moderately rich number of YSOs in this complex. Spatial distribution of the candidate YSOs shows that they are mostly clustered around the subregions in the western half of the complex, suggesting enhanced star formation activity towards its west. Using the spectral energy distribution and optical colour-magnitude diagram-based age analyses, we derived probable evolutionary status of the subregions of Sh2-252. Our analysis shows that the region A is the youngest (˜0.5 Myr), the regions B, C and E are of similar evolutionary stage (˜1-2 Myr) and the clusters NGC 2175s and Teu 136 are slightly evolved (˜2-3 Myr). Morphology of the region in the 1.1 mm map shows a semicircular shaped molecular shell composed of several clumps and YSOs bordering the western ionization front of Sh2-252. Our analyses suggest that next generation star formation is currently under way along this border and that possibly fragmentation of the matter collected during the expansion of the H II region as one of the major processes is responsible for such stars. We observed the densest concentration of YSOs (mostly Class I, ˜0.5 Myr) at the western outskirts of the complex, within a molecular clump associated with water and methanol masers and we suggest that it

  3. Enhancer Activation Requires Trans-Recruitment of a Mega Transcription Factor Complex

    PubMed Central

    Liu, Zhijie; Merkurjev, Daria; Yang, Feng; Li, Wenbo; Oh, Soohwan; Friedman, Meyer J.; Song, Xiaoyuan; Zhang, Feng; Ma, Qi; Ohgi, Kenneth; Krones, Anna; Rosenfeld, Michael G.

    2014-01-01

    Summary Enhancers provide critical information directing cell-type specific transcriptional programs, regulated by binding of signal-dependent transcription factors and their associated cofactors. Here we report that the most strongly activated estrogen (E2)-responsive enhancers are characterized by trans-recruitment and in situ assembly of a large 1-2 MDa complex of diverse DNA-binding transcription factors by ERα at ERE-containing enhancers. We refer to enhancers recruiting these factors as mega transcription factor-bound in trans (MegaTrans) enhancers. The MegaTrans complex is a signature of the most potent functional enhancers and is required for activation of enhancer RNA transcription and recruitment of coactivators, including p300 and Med1. The MegaTrans complex functions, in part, by recruiting specific enzymatic machinery, exemplified by DNA-dependent protein kinase. Thus, MegaTrans-containing enhancers represent a cohort of functional enhancers that mediate a broad and important transcriptional program and provide a molecular explanation for transcription factor clustering and hotspots noted in the genome. PMID:25303530

  4. Volumetric analysis of formation of the complex of G-quadruplex DNA with hemin using high pressure.

    PubMed

    Takahashi, Shuntaro; Bhowmik, Sudipta; Sugimoto, Naoki

    2017-01-01

    DNA guanine-quadruplexes (G-quadruplexes) complexed with the Fe-containing porphyrin, hemin (iron(III)-protoporphyrin IX), can catalyze oxidation reactions. This so-called DNAzyme has been widely used in the field of DNA nanotechnology. To improve DNAzyme properties, we sought to elucidate the interaction mechanism between G-quadruplex DNA and hemin. Here, we performed volumetric analyses of formation of the complex between an oligonucleotide with the sequence of human telomeric DNA (h-telo) and hemin. The G-quadruplex DNA alone and the G-quadruplex DNA-hemin complex were destabilized with increasing pressure in Na + buffer. The pressure required to destabilize the h-telo-hemin complex was less in K + -containing buffer than in buffer with Na + , which indicates that there was a smaller volumetric change upon h-telo formation in K + buffer than in Na + buffer. The calculated change in h-telo-hemin binding volume (∆V b ) in the Na + buffer was 2.5mLmol -1 , whereas it was -41.7 in mLmol -1 the K + buffer. The DNAzyme activity in the K + buffer was higher than that in the Na + buffer at atmospheric pressure. Interestingly, the pressure effect on the destabilization of the h-telo-hemin complex in the presence of poly(ethylene glycol)200 (PEG200) was repressed compared to that in the absence of PEG200. These results suggest that differences in volumetric parameters reflect different mechanisms of interaction between hemin and h-telo due to differences in both the fit of hemin into the h-telo structure and hydration. Thus, the pressure-based thermodynamic analysis provided important information about complex formation and could be a useful index to improve function of DNAzymes. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Isolation and Characterization of FORMATE/NI(CYCLAM)^{2+} Complexes with Cryogenic Ion Vibrational Predissociation

    NASA Astrophysics Data System (ADS)

    Wolk, Arron B.; Fournier, Joseph A.; Wolke, Conrad T.; Johnson, Mark A.

    2013-06-01

    Transition metal-based organometallic catalysts are a promising means of converting CO_{2} to transportable fuels. Ni(cyclam)^{2+}(cyclam = 1,4,8,11-tetraazacyclotetradecane), a Ni^{II} complex ligated by four nitrogen centers, has shown promise as a catalyst selective for CO_{2} reduction in aqueous solutions. The cyclam ligand has four NH hydrogen bond donors that can adopt five conformations, each offering distinct binding motifs for coordination of CO_{2} close to the metal center. To probe the ligand conformation and the role of hydrogen bonding in adduct binding, we extract Ni(cyclam)^{2+} complexes with the formate anion and some of its analogs from solution using electrospray ionization, and characterize their structures using cryogenic ion vibrational predissociation spectroscopy. Using the signature vibrational features of the embedded carboxylate anion and the NH groups as reporters, we compare the binding motifs of oxalate, benzoate, and formate anions to the Ni(cyclam)^{2+} framework. Finally, we comment on possible routes to generate the singly charged Ni(cyclam)^{+} complex, a key intermediate that has been invoked in the catalytic CO_{2} reduction cycle, but has never been isolated through ion processing techniques.

  6. Formation and Fragmentation Chemistry of Tripositive Ln(TMGA)33+ Complexes in the Gas Phase.

    PubMed

    Chen, Xiuting; Li, Qingnuan; Gong, Yu

    2017-08-01

    Electrospray ionization (ESI) of LnCl 3 (Ln = La-Lu except Pm) and TMGA (tetramethyl glutaramide) mixtures resulted in the formation of gas-phase Ln(TMGA) 3 3+ complexes, where tripositive lanthanide cation was coordinated by three neutral TMGA ligands. Collision induced dissociation (CID) was employed to investigate the fragmentation chemistry of these tripositive complexes. Ln(TMGA) 2 (TMGA- 45) 3+ resulting from C carbonyl -N bond cleavage of TMGA and hydrogen transfer is the major CID product for all Ln(TMGA) 3 3+ except Eu(TMGA) 3 3+ which predominantly forms divalent Eu II (TMGA) 2 2+ complex via loss of TMGA + . Analogous Yb II (TMGA) 2 2+ and Sm II (TMGA) 2 2+ complexes arising from charge reduction were also observed, in competition with the formation of charge conserving Yb III (TMGA)(TMGA-H) 2+ and Sm III (TMGA)(TMGA-H) 2+ products. The yield of these charge reducing products follows their reduction potentials in condensed phase. In addition to Ln(TMGA) 3 3+ , tripositive ions such as Ln(TMGA) 4 3+ and Ln(TMGA) 2 3+ were experimentally identified as well. While the former was observed along with Ln(TMGA) 3 3+ during ESI, the latter was observed upon CID of Ln(TMGA) 3 3+ , suggesting two TMGA molecules can stabilize Ln 3+ in the gas phase. Graphical Abstract ᅟ.

  7. Say again? How complexity and format of air traffic control instructions affect pilot recall

    DOT National Transportation Integrated Search

    1999-01-01

    This study compared the recall of ATC information presented in cither grouped or sequential format : in a part-task simulation. It also tested the effect of complexity of ATC clearances on recall, that is, : how many pieces of information a single tr...

  8. HTLV-1 Tax Induces Formation of the Active Macromolecular IKK Complex by Generating Lys63- and Met1-Linked Hybrid Polyubiquitin Chains

    PubMed Central

    Tokunaga, Fuminori; Goto, Eiji; Komatsu, Ginga; Saeki, Yasushi; Tanaka, Keiji; Takahashi, Hirotaka; Sawasaki, Tatsuya; Inoue, Satoshi; Oshiumi, Hiroyuki; Seya, Tsukasa; Nakano, Hiroyasu; Tanaka, Yuetsu; Iwai, Kazuhiro

    2017-01-01

    The Tax protein of human T-cell leukemia virus type 1 (HTLV-1) is crucial for the development of adult T-cell leukemia (ATL), a highly malignant CD4+ T cell neoplasm. Among the multiple aberrant Tax-induced effects on cellular processes, persistent activation of transcription factor NF-κB, which is activated only transiently upon physiological stimulation, is essential for leukemogenesis. We and others have shown that Tax induces activation of the IκB kinase (IKK) complex, which is a critical step in NF-κB activation, by generating Lys63-linked polyubiquitin chains. However, the molecular mechanism underlying Tax-induced IKK activation is controversial and not fully understood. Here, we demonstrate that Tax recruits linear (Met1-linked) ubiquitin chain assembly complex (LUBAC) to the IKK complex and that Tax fails to induce IKK activation in cells that lack LUBAC activity. Mass spectrometric analyses revealed that both Lys63-linked and Met1-linked polyubiquitin chains are associated with the IKK complex. Furthermore, treatment of the IKK-associated polyubiquitin chains with Met1-linked-chain-specific deubiquitinase (OTULIN) resulted in the reduction of high molecular weight polyubiquitin chains and the generation of short Lys63-linked ubiquitin chains, indicating that Tax can induce the generation of Lys63- and Met1-linked hybrid polyubiquitin chains. We also demonstrate that Tax induces formation of the active macromolecular IKK complex and that the blocking of Tax-induced polyubiquitin chain synthesis inhibited formation of the macromolecular complex. Taken together, these results lead us to propose a novel model in which the hybrid-chain-dependent oligomerization of the IKK complex triggered by Tax leads to trans-autophosphorylation-mediated IKK activation. PMID:28103322

  9. Inhibition of buckwheat starch digestion by the formation of starch/bile salt complexes: possibility of its occurrence in the intestine.

    PubMed

    Takahama, Umeo; Hirota, Sachiko

    2011-06-08

    During the digestion of starch in foods, starch is mixed with bile in the duodenum. Because fatty acids and some kinds of polyphenols could bind to starch, it was postulated that bile salts might also bind to starch. The purpose of this paper is to study the effects of bile and bile salts on starch/iodine complex formation and pancreatin-induced starch digestion. Bile suppressed starch/iodine complex formation and inhibited pancreatin-induced starch digestion slightly in control buckwheat starch, but did so significantly in buckwheat starch from which fatty acids and polyphenols had been extracted. Such significant suppression and inhibition by bile were also observed in a reagent soluble starch. The effects of cholate and taurocholate on the starch/iodine complex formation and the pancreatin-induced starch digestion were essentially the same as those of bile. Bile, cholate, and taurocholate suppressed amylose/iodine complex formation more significantly than amylopectin/iodine complex formation and inhibited pancreatin-induced amylose digestion more effectively than the digestion of amylopectin. It is concluded from the results that bile salts could bind to starch, especially amylose, the helical structures of which were not occupied by other molecules such as fatty acids and polyphenols, and that the binding resulted in the inhibition of starch digestion by pancreatin. The conclusion suggests that the function of bile salts can be discussed from the point of not only lipid digestion but also starch digestion.

  10. Green synthesis of ZnO nanoparticles via complex formation by using Curcuma longa extract

    NASA Astrophysics Data System (ADS)

    Fatimah, Is; Yudha, Septian P.; Mutiara, Nur Afisa Lintang

    2016-02-01

    Synthesis of ZnO nanoparticles(NPs) were conducted via Zn(II) complex formation by using Curcuma longa extract as template. Curcuma longa extract has the ability to form zinc ions complex with curcumin as ligating agent. Study on synthesis was conducted by monitoring thermal degradation of the material. Successful formation of zinc oxide nanoparticles was confirmed by employing x-ray diffraction, surface area analysis and transmission electron microscopy(TEM) studies. From the XRD analysis it is denoted that ZnO in hexagonal wurtzite phase was formed and particle size was varied as varied temperature. The data are also confirmed by TEM analysis which shows the particle sie at the range 20-80nm. The NPs exhibited excelent photocatalytic activity for methylene blue degradation and also significant antibacterial activity for Eschericia coli. The activity in methylene blue degradation was also confirmed from fast chemical oxygen demand (COD) reduction.

  11. Effect of Tween 80 on formation of the superficial L1 layer of the Mycobacterium avium-Mycobacterium intracellulare complex.

    PubMed Central

    Masaki, S; Sugimori, G; Okamoto, A; Imose, J; Hayashi, Y

    1991-01-01

    The effects of Tween 80 supplementation of liquid culture medium on the formation of the superficial L1 layer of the Mycobacterium avium-Mycobacterium intracellulare complex (MAC) were examined by serological and scanning electron microscopic experiments. Specific antiserum to the glycopeptidolipids on the L1 layer of M. avium S-139, made in a rabbit, was used for seroagglutination reactions with antigens prepared from strain S-139 grown in medium supplemented with various levels of Tween 80 (0, 0.05, 0.5, 5, and 50 mg/ml). The agglutination titers gradually decreased as the concentration of Tween 80 rose. Scanning electron microscopy showed that the fibrillar materials consisting mainly of glycopeptidolipids on the L1 layer of strain S-139 also disappeared with increases in the concentration of Tween 80. In addition, there was no obvious correlation between (i) the plasmid DNAs and serotypes of MAC and (ii) formation of the L1 layer of MAC. It is therefore concluded that Tween 80 used to supplement liquid culture medium affects formation of the L1 layer, which has been considered to be one of the pathogenic factors of MAC. Images PMID:1885740

  12. Hrs regulates early endosome fusion by inhibiting formation of an endosomal SNARE complex

    PubMed Central

    Sun, Wei; Yan, Qing; Vida, Thomas A.; Bean, Andrew J.

    2003-01-01

    Movement through the endocytic pathway occurs principally via a series of membrane fusion and fission reactions that allow sorting of molecules to be recycled from those to be degraded. Endosome fusion is dependent on SNARE proteins, although the nature of the proteins involved and their regulation has not been fully elucidated. We found that the endosome-associated hepatocyte responsive serum phosphoprotein (Hrs) inhibited the homotypic fusion of early endosomes. A region of Hrs predicted to form a coiled coil required for binding the Q-SNARE, SNAP-25, mimicked the inhibition of endosome fusion produced by full-length Hrs, and was sufficient for endosome binding. SNAP-25, syntaxin 13, and VAMP2 were bound from rat brain membranes to the Hrs coiled-coil domain. Syntaxin 13 inhibited early endosomal fusion and botulinum toxin/E inhibition of early endosomal fusion was reversed by addition of SNAP-25(150–206), confirming a role for syntaxin 13, and establishing a role for SNAP-25 in endosomal fusion. Hrs inhibited formation of the syntaxin 13–SNAP-25–VAMP2 complex by displacing VAMP2 from the complex. These data suggest that SNAP-25 is a receptor for Hrs on early endosomal membranes and that the binding of Hrs to SNAP-25 on endosomal membranes inhibits formation of a SNARE complex required for homotypic endosome fusion. PMID:12847087

  13. Effect of the ordered interfacial water layer in protein complex formation: a non-local electrostatic approach

    NASA Astrophysics Data System (ADS)

    Rubinstein, Alexander; Sabirianov, Renat

    2011-03-01

    Using a non-local electrostatic approach that incorporates the short-range structure of the contacting media, we evaluated the electrostatic contribution to the energy of the complex formation of two model proteins. In this study, we have demonstrated that the existence of an low-dielectric interfacial water layer at the protein-solvent interface reduces the charging energy of the proteins in the aqueous solvent, and consequently increases the electrostatic contribution to the protein binding (change in free energy upon the complex formation of two proteins). This is in contrast with the finding of the continuum electrostatic model, which suggests that electrostatic interactions are not strong enough to compensate for the unfavorable desolvation effects.

  14. Formate and its role in hydrogen production in Escherichia coli.

    PubMed

    Sawers, R G

    2005-02-01

    The production of dihydrogen by Escherichia coli and other members of the Enterobacteriaceae is one of the classic features of mixed-acid fermentation. Synthesis of the multicomponent, membrane-associated FHL (formate hydrogenlyase) enzyme complex, which disproportionates formate into CO(2) and H(2), has an absolute requirement for formate. Formate, therefore, represents a signature molecule in the fermenting E. coli cell and factors that determine formate metabolism control FHL synthesis and consequently dihydrogen evolution.

  15. Protein complexing in a methanogen suggests electron bifurcation and electron delivery from formate to heterodisulfide reductase.

    PubMed

    Costa, Kyle C; Wong, Phoebe M; Wang, Tiansong; Lie, Thomas J; Dodsworth, Jeremy A; Swanson, Ingrid; Burn, June A; Hackett, Murray; Leigh, John A

    2010-06-15

    In methanogenic Archaea, the final step of methanogenesis generates methane and a heterodisulfide of coenzyme M and coenzyme B (CoM-S-S-CoB). Reduction of this heterodisulfide by heterodisulfide reductase to regenerate HS-CoM and HS-CoB is an exergonic process. Thauer et al. [Thauer, et al. 2008 Nat Rev Microbiol 6:579-591] recently suggested that in hydrogenotrophic methanogens the energy of heterodisulfide reduction powers the most endergonic reaction in the pathway, catalyzed by the formylmethanofuran dehydrogenase, via flavin-based electron bifurcation. Here we present evidence that these two steps in methanogenesis are physically linked. We identify a protein complex from the hydrogenotrophic methanogen, Methanococcus maripaludis, that contains heterodisulfide reductase, formylmethanofuran dehydrogenase, F(420)-nonreducing hydrogenase, and formate dehydrogenase. In addition to establishing a physical basis for the electron-bifurcation model of energy conservation, the composition of the complex also suggests that either H(2) or formate (two alternative electron donors for methanogenesis) can donate electrons to the heterodisulfide-H(2) via F(420)-nonreducing hydrogenase or formate via formate dehydrogenase. Electron flow from formate to the heterodisulfide rather than the use of H(2) as an intermediate represents a previously unknown path of electron flow in methanogenesis. We further tested whether this path occurs by constructing a mutant lacking F(420)-nonreducing hydrogenase. The mutant displayed growth equal to wild-type with formate but markedly slower growth with hydrogen. The results support the model of electron bifurcation and suggest that formate, like H(2), is closely integrated into the methanogenic pathway.

  16. Three-color single molecule imaging shows WASP detachment from Arp2/3 complex triggers actin filament branch formation

    PubMed Central

    Smith, Benjamin A; Padrick, Shae B; Doolittle, Lynda K; Daugherty-Clarke, Karen; Corrêa, Ivan R; Xu, Ming-Qun; Goode, Bruce L; Rosen, Michael K; Gelles, Jeff

    2013-01-01

    During cell locomotion and endocytosis, membrane-tethered WASP proteins stimulate actin filament nucleation by the Arp2/3 complex. This process generates highly branched arrays of filaments that grow toward the membrane to which they are tethered, a conflict that seemingly would restrict filament growth. Using three-color single-molecule imaging in vitro we revealed how the dynamic associations of Arp2/3 complex with mother filament and WASP are temporally coordinated with initiation of daughter filament growth. We found that WASP proteins dissociated from filament-bound Arp2/3 complex prior to new filament growth. Further, mutations that accelerated release of WASP from filament-bound Arp2/3 complex proportionally accelerated branch formation. These data suggest that while WASP promotes formation of pre-nucleation complexes, filament growth cannot occur until it is triggered by WASP release. This provides a mechanism by which membrane-bound WASP proteins can stimulate network growth without restraining it. DOI: http://dx.doi.org/10.7554/eLife.01008.001 PMID:24015360

  17. Three-color single molecule imaging shows WASP detachment from Arp2/3 complex triggers actin filament branch formation.

    PubMed

    Smith, Benjamin A; Padrick, Shae B; Doolittle, Lynda K; Daugherty-Clarke, Karen; Corrêa, Ivan R; Xu, Ming-Qun; Goode, Bruce L; Rosen, Michael K; Gelles, Jeff

    2013-09-03

    During cell locomotion and endocytosis, membrane-tethered WASP proteins stimulate actin filament nucleation by the Arp2/3 complex. This process generates highly branched arrays of filaments that grow toward the membrane to which they are tethered, a conflict that seemingly would restrict filament growth. Using three-color single-molecule imaging in vitro we revealed how the dynamic associations of Arp2/3 complex with mother filament and WASP are temporally coordinated with initiation of daughter filament growth. We found that WASP proteins dissociated from filament-bound Arp2/3 complex prior to new filament growth. Further, mutations that accelerated release of WASP from filament-bound Arp2/3 complex proportionally accelerated branch formation. These data suggest that while WASP promotes formation of pre-nucleation complexes, filament growth cannot occur until it is triggered by WASP release. This provides a mechanism by which membrane-bound WASP proteins can stimulate network growth without restraining it. DOI:http://dx.doi.org/10.7554/eLife.01008.001.

  18. Formation, Detection and the Distribution of Complex Organic Molecules with the Atacama Large Millimeter/submillimeter Array (ALMA)

    NASA Astrophysics Data System (ADS)

    Remijan, Anthony John

    2015-08-01

    The formation and distribution of complex organic material in astronomical environments continues to be a focused research area in astrochemistry. For several decades now, emphasis has been placed on the millimeter/submillimeter regime of the radio spectrum for trying to detect new molecular species and to constrain the chemical formation route of complex molecules by comparing and contrasting their relative distributions towards varying astronomical environments. This effort has been extremely laborious as millimeter/submillimeter facilities have been only able to detect and map the distribution of the strongest transition(s) of the simplest organic molecules. Even then, these single transition "chemical maps" have been very low spatial resolution because early millimeter/submillimeter facilities did not have access to broadband spectral coverage or the imaging capabilities to truly ascertain the morphology of the molecular emission. In the era of ALMA, these limitations have been greatly lifted. Broadband spectral line surveys now hold the key to uncovering the full molecular complexity in astronomical environments. In addition, searches for complex organic material is no longer limited to investigating the strongest lines of the simplest molecules toward the strongest sources of emission in the Galaxy. ALMA is issuing a new era of exploration as the search for complex molecules will now be available to an increased suite of sources in the Galaxy and our understanding of the formation of this complex material will be greatly increased as a result. This presentation will highlight the current and future ALMA capabilities in the search for complex molecules towards astronomical environments, highlight the recent searches that ALMA scientists have conducted from the start of ALMA Early Science and provide the motivation for the next suite of astronomical searches to investigate our pre-biotic origins in the universe.

  19. Structural impact of complete CpG methylation within target DNA on specific complex formation of the inducible transcription factor Egr-1.

    PubMed

    Zandarashvili, Levani; White, Mark A; Esadze, Alexandre; Iwahara, Junji

    2015-07-08

    The inducible transcription factor Egr-1 binds specifically to 9-bp target sequences containing two CpG sites that can potentially be methylated at four cytosine bases. Although it appears that complete CpG methylation would make an unfavorable steric clash in the previous crystal structures of the complexes with unmethylated or partially methylated DNA, our affinity data suggest that DNA recognition by Egr-1 is insensitive to CpG methylation. We have determined, at a 1.4-Å resolution, the crystal structure of the Egr-1 zinc-finger complex with completely methylated target DNA. Structural comparison of the three different methylation states reveals why Egr-1 can recognize the target sequences regardless of CpG methylation. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  20. Metal-assisted in situ formation of a tridentate acetylacetone ligand for complexation of fac-Re(CO)3+ for radiopharmaceutical applications.

    PubMed

    Benny, Paul D; Fugate, Glenn A; Barden, Adam O; Morley, Jennifer E; Silva-Lopez, Elsa; Twamley, Brendan

    2008-04-07

    Reaction of [NEt4]2[ReBr3(CO)3] with 2,4-pentanedione (acac) yields a complex of the type fac-Re(acac)(OH2)(CO)3 (1) under aqueous conditions. 1 was further reacted with a monodentate ligand (pyridine) to yield a fac-Re(acac)(pyridine)(CO)3 complex (2). Complex 1 was found to react with primary amines to generate a Schiff base (imine) in aqueous solutions. When a mixed-nitrogen donor bidentate ligand, 2-(2-aminoethyl)pyridine, that has different coordination affinities for fac-Re(acac)(OH2)(CO)3 was utilized, a unique tridentate ligand was formed in situ utilizing a metal-assisted Schiff base formation to yield a complex fac-Re(CO)3(3[(2-phenylethyl)imino]-2-pentanone) (3). Tridentate ligand formation was found to occur only with the Re-coordinated acac ligand. Reactions of acac with fac-Re(CO)3Br(2-(2-aminoethyl)pyridine) (4) or a mixture of [NEt4]2[ReBr3(CO)3], acac, and 2-(2-aminoethyl)pyridine did not yield the formation of complex 3 in water.

  1. Factors influencing visual search in complex driving environments.

    DOT National Transportation Integrated Search

    2016-10-01

    The objective of this study was to describe and model the effects of varied roadway environment factors on drivers perceived complexity, with the goal of further understanding conditions for optimal driver behavior and performance. This was invest...

  2. Implementing complex innovations: factors influencing middle manager support.

    PubMed

    Chuang, Emmeline; Jason, Kendra; Morgan, Jennifer Craft

    2011-01-01

    Middle manager resistance is often described as a major challenge for upper-level administrators seeking to implement complex innovations such as evidence-based protocols or new skills training. However, factors influencing middle manager support for innovation implementation are currently understudied in the U.S. health care literature. This article examined the factors that influence middle managers' support for and participation in the implementation of work-based learning, a complex innovation adopted by health care organizations to improve the jobs, educational pathways, skills, and/or credentials of their frontline workers. We conducted semistructured interviews and focus groups with 92 middle managers in 17 health care organizations. Questions focused on understanding middle managers' support for work-based learning as a complex innovation, facilitators and barriers to the implementation process, and the systems changes needed to support the implementation of this innovation. Factors that emerged as influential to middle manager support were similar to those found in broader models of innovation implementation within the health care literature. However, our findings extend previous research by developing an understanding about how middle managers perceived these constructs and by identifying specific strategies for how to influence middle manager support for the innovation implementation process. These findings were generally consistent across different types of health care organizations. Study findings suggest that middle manager support was highest when managers felt the innovation fit their workplace needs and priorities and when they had more discretion and control over how it was implemented. Leaders seeking to implement innovations should consider the interplay between middle managers' control and discretion, their narrow focus on the performance of their own departments or units, and the dedication of staff and other resources for empowering their

  3. Kinetic and mechanism formation reaction of complex compound Cu with di-n-buthildithiocarbamate (dbdtc) ligand

    NASA Astrophysics Data System (ADS)

    Haryani, S.; Kurniawan, C.; Kasmui

    2018-04-01

    Synthesis of complex compound is one field of research which intensively studied. Metal-dithiocarbamate complexes find wide-ranging applications in nanomaterial and metal separation science, and have potential use as chemotherapeutic, pesticides, and as additives to lubricants. However, the information about is reaction kinetic and mechanism are very much lacking. The research and analyzes results show that reaction synthesis ligand DBDTC and complex compounds Cu-DBDTC. Optimum reaction condition of formation of complex compounds Cu with DBDTC at pH=3, [DBDTC] = 4.10-3 M, and the time of reaction 5 minutes. Based the analysis varian reaction of complex compounds at pH 3 and 4, diffrence significance at the other pH: 5; 5,5; 6; 6,5 ; 7; and 8. The various of mole with reactants comosition difference sigbificance, those the time reaction for 5 and 6 minutes diffrence by significance with the other time, it is 3,4,8, and 10 minutes. The great product to at condition pH 6, the time optimum at 5 minutes and molar ratio of logam: ligand = 1:2. The reaction kinetic equation of complex compound Cu with chelathing ligand DBDTC is V=0.917106 [Cu2+]0.87921 [DBDTC]2.03021. Based on the kinetic data, and formed complex compounds estimation, the mechanism explaining by 2 stages. In the first stage formation of [Cu(DBDTC)], and then [Cu(DBDTC)2] with the last structure geomethry planar rectangle. The result of this research will be more useful if an effort is being done in reaction mechanism by chemical computation method for obtain intermediate, and for constant “k” in same stage, k1.k2. and compound complex constanta (β).

  4. Identification of Factors That Affect Software Complexity.

    ERIC Educational Resources Information Center

    Kaiser, Javaid

    A survey of computer scientists was conducted to identify factors that affect software complexity. A total of 160 items were selected from the literature to include in a questionnaire sent to 425 individuals who were employees of computer-related businesses in Lawrence and Kansas City. The items were grouped into nine categories called system…

  5. Green synthesis of ZnO nanoparticles via complex formation by using Curcuma longa extract

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fatimah, Is, E-mail: isfatimah@uii.ac.id; Yudha, Septian P.; Mutiara, Nur Afisa Lintang

    Synthesis of ZnO nanoparticles(NPs) were conducted via Zn(II) complex formation by using Curcuma longa extract as template. Curcuma longa extract has the ability to form zinc ions complex with curcumin as ligating agent. Study on synthesis was conducted by monitoring thermal degradation of the material. Successful formation of zinc oxide nanoparticles was confirmed by employing x-ray diffraction, surface area analysis and transmission electron microscopy(TEM) studies. From the XRD analysis it is denoted that ZnO in hexagonal wurtzite phase was formed and particle size was varied as varied temperature. The data are also confirmed by TEM analysis which shows the particlemore » sie at the range 20-80nm. The NPs exhibited excelent photocatalytic activity for methylene blue degradation and also significant antibacterial activity for Eschericia coli. The activity in methylene blue degradation was also confirmed from fast chemical oxygen demand (COD) reduction.« less

  6. Hemolymph Melanization in the Silkmoth Bombyx mori Involves Formation of a High Molecular Mass Complex That Metabolizes Tyrosine*

    PubMed Central

    Clark, Kevin D.; Strand, Michael R.

    2013-01-01

    The phenoloxidase (PO) cascade regulates the melanization of blood (hemolymph) in insects and other arthropods. Most studies indicate that microbial elicitors activate the PO cascade, which results in processing of the zymogen PPO to PO. PO is then thought to oxidize tyrosine and o-diphenols to quinones, which leads to melanin. However, different lines of investigation raise questions as to whether these views are fully correct. Here we report that hemolymph from the silkmoth, Bombyx mori, rapidly melanizes after collection from a wound site. Prior studies indicated that in vitro activated PPO hydroxylates Tyr inefficiently. Measurement of in vivo substrate titers, however, suggested that Tyr was the only PO substrate initially present in B. mori plasma and that it is rapidly metabolized by PO. Fractionation of plasma by gel filtration chromatography followed by bioassays indicated that melanization activity was primarily associated with a high mass complex (∼670 kDa) that contained PO. The prophenoloxidase-activating protease inhibitor Egf1.0 blocked formation of this complex and Tyr metabolism, but the addition of phenylthiourea to plasma before fractionation enhanced complex formation and Tyr metabolism. Mass spectrometry analysis indicated that the complex contained PO plus other proteins. Taken together, our results indicate that wounding alone activates the PO cascade in B. mori. They also suggest that complex formation is required for efficient use of Tyr as a substrate. PMID:23553628

  7. The influence of water-ethanol mixture on the thermodynamics of complex formation between 18-crown-6 ether and L-phenylalanine

    NASA Astrophysics Data System (ADS)

    Usacheva, T. R.; Sharnin, V. A.; Chernov, I. V.; Matteoli, E.; Terekhova, I. V.; Kumeev, R. S.

    2012-08-01

    The influence of water-ethanol mixture composition on the complex formation between 18-crown-6 ether and L-phenylalanine was studied by titration calorimetry at Т = 298.15 K. The standard thermodynamic parameters (ΔrGо, ΔrHо, ТΔrSо) of formation of [Phe18C6] molecular complex were calculated from data obtained by means of the microcalorimetric system TAM III (TA Instruments, USA) at X(EtOH) = 0.0/0.6 mol fraction. The stability of [Phe18C6] and the mechanism of complexation in water were investigated using the 1Н and 13С NMR spectroscopy. The increase of EtOH concentration results in an increase of the complex stability and of the exothermicity of complexation.

  8. Complex Organic Molecules Formation in Space Through Gas Phase Reactions: A Theoretical Approach

    NASA Astrophysics Data System (ADS)

    Redondo, Pilar; Barrientos, Carmen; Largo, Antonio

    2017-02-01

    Chemistry in the interstellar medium (ISM) is capable of producing complex organic molecules (COMs) of great importance to astrobiology. Gas phase and grain surface chemistry almost certainly both contribute to COM formation. Amino acids as building blocks of proteins are some of the most interesting COMs. The simplest one, glycine, has been characterized in meteorites and comets and, its conclusive detection in the ISM seems to be highly plausible. In this work, we analyze the gas phase reaction of glycine and {{{CH}}5}+ to establish the role of this process in the formation of alanine or other COMs in the ISM. Formation of protonated α- and β-alanine in spite of being exothermic processes is not viable under interstellar conditions because the different paths leading to these isomers present net activation energies. Nevertheless, glycine can evolve to protonated 1-imide-2, 2-propanediol, protonated amino acetone, protonated hydroxyacetone, and protonated propionic acid. However, formation of acetic acid and protonated methylamine is also a favorable process and therefore will be a competitive channel with the evolution of glycine to COMs.

  9. DEAD-box helicase DDX27 regulates 3′ end formation of ribosomal 47S RNA and stably associates with the PeBoW-complex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kellner, Markus; Rohrmoser, Michaela; Forné, Ignasi

    PeBoW, a trimeric complex consisting of pescadillo (Pes1), block of proliferation (Bop1), and the WD repeat protein 12 (WDR12), is essential for processing and maturation of mammalian 5.8S and 28S ribosomal RNAs. Applying a mass spectrometric analysis, we identified the DEAD-box helicase DDX27 as stably associated factor of the PeBoW-complex. DDX27 interacts with the PeBoW-complex via an evolutionary conserved F×F motif in the N-terminal domain and is recruited to the nucleolus via its basic C-terminal domain. This recruitment is RNA-dependent and occurs independently of the PeBoW-complex. Interestingly, knockdown of DDX27, but not of Pes1, induces the accumulation of an extendedmore » form of the primary 47S rRNA. We conclude that DDX27 can interact specifically with the Pes1 and Bop1 but fulfils critical function(s) for proper 3′ end formation of 47S rRNA independently of the PeBoW-complex. - Highlights: • DEAD-box helicase DDX27 is a new constituent of the PeBoW-complex. • The N-terminal F×F motif of DDX27 interacts with the PeBoW components Pes1 and Bop1. • Nucleolar anchoring of DDX27 via its basic C-terminal domain is RNA dependent. • Knockdown of DDX27 induces a specific defect in 3′ end formation of 47S rRNA.« less

  10. The Nuclear Transport Factor Kap121 Is Required for Stability of the Dam1 Complex and Mitotic Kinetochore Bi-orientation.

    PubMed

    Cairo, Lucas V; Wozniak, Richard W

    2016-03-15

    The karyopherin (Kap) family of nuclear transport factors facilitates macromolecular transport through nuclear pore complexes (NPCs). The binding of Kaps to their cargos can also regulate, both temporally and spatially, the interactions of the cargo protein with interacting partners. Here, we show that the essential yeast Kap, Kap121, binds Dam1 and Duo1, components of the microtubule (MT)-associated Dam1 complex required for linking dynamic MT ends with kinetochores (KTs). Like mutations in the Dam1 complex, loss of Kap121 function compromises the formation of normal KT-MT attachments during mitosis. We show that the stability of the Dam1 complex in vivo is dependent on its association with Kap121. Furthermore, we show that the Kap121/Duo1 complex is maintained in the presence of RanGTP but Kap121 is released by the cooperative actions of RanGTP and tubulin. We propose that Kap121 stabilizes the Dam1 complex and participates in escorting it to spindle MTs. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Actomyosin-dependent formation of the mechanosensitive talin–vinculin complex reinforces actin anchoring

    PubMed Central

    Ciobanasu, Corina; Faivre, Bruno; Le Clainche, Christophe

    2014-01-01

    The force generated by the actomyosin cytoskeleton controls focal adhesion dynamics during cell migration. This process is thought to involve the mechanical unfolding of talin to expose cryptic vinculin-binding sites. However, the ability of the actomyosin cytoskeleton to directly control the formation of a talin–vinculin complex and the resulting activity of the complex are not known. Here we develop a microscopy assay with pure proteins in which the self-assembly of actomyosin cables controls the association of vinculin to a talin-micropatterned surface in a reversible manner. Quantifications indicate that talin refolding is limited by vinculin dissociation and modulated by the actomyosin network stability. Finally, we show that the activation of vinculin by stretched talin induces a positive feedback that reinforces the actin–talin–vinculin association. This in vitro reconstitution reveals the mechanism by which a key molecular switch senses and controls the connection between adhesion complexes and the actomyosin cytoskeleton. PMID:24452080

  12. Formation of HDL-like complexes from apolipoprotein A-I(M) and DMPC.

    PubMed

    Suurkuusk, M; Singh, S K

    2000-01-20

    Conditions for the preparation of reconstituted high density lipoproteins (HDLs) by incubation of the synthetic lipid dimyristoylphosphatidylcholine (DMPC) and recombinant apolipoprotein A-I(M) have been investigated as a function of ratio of incubation lipid to protein, incubation temperature and the lipid form (multilamellar (MLV) or small unilamellar (SUV) vesicles). The size distributions of the resultant lipid-protein complex particles from various incubations have been evaluated by native gel electrophoresis. Structural changes of the protein after incorporation into these complex particles have been estimated by CD. Thermal characteristics of the particles has been examined by DSC and correlated with CD results. Titration calorimetry has been used to obtain interaction parameters based on a simplified binding model. It is hypothesized that the major enthalpic step in the production of rHDLs is the primary association step between protein and lipid vesicles. It has been shown that by raising the temperature and incubation ratio, the formation of rHDL particles can be directed towards smaller size and a narrower size distribution. The results have been described on the basis of a model where formation of discoidal particles requires prior saturation of vesicle surface area by adsorbed protein, thus explaining differences between particles formed from MLVs and SUVs.

  13. NDMA formation during drinking water treatment: A multivariate analysis of factors influencing formation.

    PubMed

    Leavey-Roback, Shannon L; Sugar, Catherine A; Krasner, Stuart W; Suffet, Irwin H Mel

    2016-05-15

    The formation of the carcinogen N-nitrosodimethylamine (NDMA) during drinking water treatment has raised concerns in the drinking water industry. Many bench-scale laboratory tests and pilot plant studies have been completed to try to determine which factors during water treatment increase or decrease the amount of NDMA formed in drinking water. This study used data from over 20 drinking water treatment plants in the United States and Canada to determine which factors are most highly correlated with the NDMA concentration in delivered water using a mixed effects model with a random intercept. This type of analysis has not been used previously with trihalomethane (THM) models due to the fact that those studies did not sample such a large number and range of plants as was done in this NDMA study. Ultraviolet absorbance at 254 nm (UV254) in the plant influent and pre-chlorination time used at the plant were highly correlated in all models with NDMA concentration in finished water as well as the percentage change between NDMA formation potential in the plant influent and actual formation in the finished water. Specifically, an increase in UV254 absorbance in a model was associated with an increase in NDMA and an increase in pre-chlorination time in a model was associated with a decrease in NDMA. Other water quality parameters including sucralose concentration in the plant influent, polyDADMAC polymer dose, pH, and chlorine-to-ammonia weight ratio used in the plant were also correlated with NDMA concentration in the distribution system. Lastly, NDMA precursor loading was correlated with the use of polyDADMAC (where precursors were added) and the use of ozone and granular activated carbon (GAC) treatment (where precursors were removed). Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Epithelial junction formation requires confinement of Cdc42 activity by a novel SH3BP1 complex

    PubMed Central

    Elbediwy, Ahmed; Zihni, Ceniz; Terry, Stephen J.; Clark, Peter

    2012-01-01

    Epithelial cell–cell adhesion and morphogenesis require dynamic control of actin-driven membrane remodeling. The Rho guanosine triphosphatase (GTPase) Cdc42 regulates sequential molecular processes during cell–cell junction formation; hence, mechanisms must exist that inactivate Cdc42 in a temporally and spatially controlled manner. In this paper, we identify SH3BP1, a GTPase-activating protein for Cdc42 and Rac, as a regulator of junction assembly and epithelial morphogenesis using a functional small interfering ribonucleic acid screen. Depletion of SH3BP1 resulted in loss of spatial control of Cdc42 activity, stalled membrane remodeling, and enhanced growth of filopodia. SH3BP1 formed a complex with JACOP/paracingulin, a junctional adaptor, and CD2AP, a scaffolding protein; both were required for normal Cdc42 signaling and junction formation. The filamentous actin–capping protein CapZ also associated with the SH3BP1 complex and was required for control of actin remodeling. Epithelial junction formation and morphogenesis thus require a dual activity complex, containing SH3BP1 and CapZ, that is recruited to sites of active membrane remodeling to guide Cdc42 signaling and cytoskeletal dynamics. PMID:22891260

  15. The equilibrium constant of complex formation in solution: A study utilizing a dielectric constant method

    NASA Astrophysics Data System (ADS)

    Loh, C. W.

    1980-03-01

    A method was developed for determining equilibrium constants, heat of reaction, and change in free energy and entropy during a 1:1 complex formation in solutions. The measurements were carried out on ternary systems containing two interacting solutes in an inert solvent. The procedures was applied to the investigation of hydrogen bond complex formations in two mixtures systems, phenol and pyridine in carbon tetrachloride, and 4, 5, 6, 7-tetrachloro-2-trifluoromethylbenzimidazole (TTFB) and alkyl acetate in styrene. The first mixture system was studied in order to compare the results with those obtained by other methods. Results for the second mixture system indicated strong association between molecules of TTFB and alkyl acetate and suggested that the blocking of valinomycin-mediated bilayer membrane conductance by substituted benzimidazoles was due to competition for a limited number of adsorption sites on the membrane surface.

  16. Regulation of Memory Formation by the Transcription Factor XBP1.

    PubMed

    Martínez, Gabriela; Vidal, René L; Mardones, Pablo; Serrano, Felipe G; Ardiles, Alvaro O; Wirth, Craig; Valdés, Pamela; Thielen, Peter; Schneider, Bernard L; Kerr, Bredford; Valdés, Jose L; Palacios, Adrian G; Inestrosa, Nibaldo C; Glimcher, Laurie H; Hetz, Claudio

    2016-02-16

    Contextual memory formation relies on the induction of new genes in the hippocampus. A polymorphism in the promoter of the transcription factor XBP1 was identified as a risk factor for Alzheimer's disease and bipolar disorders. XBP1 is a major regulator of the unfolded protein response (UPR), mediating adaptation to endoplasmic reticulum (ER) stress. Using a phenotypic screen, we uncovered an unexpected function of XBP1 in cognition and behavior. Mice lacking XBP1 in the nervous system showed specific impairment of contextual memory formation and long-term potentiation (LTP), whereas neuronal XBP1s overexpression improved performance in memory tasks. Gene expression analysis revealed that XBP1 regulates a group of memory-related genes, highlighting brain-derived neurotrophic factor (BDNF), a key component in memory consolidation. Overexpression of BDNF in the hippocampus reversed the XBP1-deficient phenotype. Our study revealed an unanticipated function of XBP1 in cognitive processes that is apparently unrelated to its role in ER stress. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  17. The cellular transcription factor CREB corresponds to activating transcription factor 47 (ATF-47) and forms complexes with a group of polypeptides related to ATF-43.

    PubMed

    Hurst, H C; Masson, N; Jones, N C; Lee, K A

    1990-12-01

    Promoter elements containing the sequence motif CGTCA are important for a variety of inducible responses at the transcriptional level. Multiple cellular factors specifically bind to these elements and are encoded by a multigene family. Among these factors, polypeptides termed activating transcription factor 43 (ATF-43) and ATF-47 have been purified from HeLa cells and a factor referred to as cyclic AMP response element-binding protein (CREB) has been isolated from PC12 cells and rat brain. We demonstrated that CREB and ATF-47 are identical and that CREB and ATF-43 form protein-protein complexes. We also found that the cis requirements for stable DNA binding by ATF-43 and CREB are different. Using antibodies to ATF-43 we have identified a group of polypeptides (ATF-43) in the size range from 40 to 43 kDa. ATF-43 polypeptides are related by their reactivity with anti-ATF-43, DNA-binding specificity, complex formation with CREB, heat stability, and phosphorylation by protein kinase A. Certain cell types vary in their ATF-43 complement, suggesting that CREB activity is modulated in a cell-type-specific manner through interaction with ATF-43. ATF-43 polypeptides do not appear simply to correspond to the gene products of the ATF multigene family, suggesting that the size of the ATF family at the protein level is even larger than predicted from cDNA-cloning studies.

  18. Exhaustive oxidation of a nickel dithiolate complex: some mechanistic insights en route to sulfate formation.

    PubMed

    Hosler, Erik R; Herbst, Robert W; Maroney, Michael J; Chohan, Balwant S

    2012-01-21

    A study of the step-wise oxidation of a Ni(II) diaminodithiolate complex through the formation of sulfate, the ultimate sulfur oxygenate, is reported. Controlled oxygenations or peroxidations of a neutral, planar, tetracoordinate, low-spin Ni(II) complex of a N(2)S(2)-donor ligand, (N,N'-dimethyl-N-N'-bis(2-mecaptoethyl)-1,3-propanediaminato) nickel(ii) (1), led to a series of sulfur oxygenates that have been isolated and characterized by ESI-MS and single-crystal X-ray diffraction. A monosulfenate complex (2) was detected by ESI-MS as a product of oxidation with one equivalent of H(2)O(2). However, this complex proved too unstable to isolate. Reaction of the dithiolate (1) with two equivalents of H(2)O(2) or one O(2) molecule leads to the formation of a monosulfinate complex (3), which was isolated and fully characterized by crystallography. The oxidation product of the monosulfinate (3) produced with either O(2) or H(2)O(2) is an interesting dimeric complex containing both sulfonate and thiolate ligands (4), this complex was fully characterized by crystallography, details of which were reported earlier by us. A disulfonate complex (7) is produced by reaction of 1 in the presence of O(2) or by reaction with exactly six equivalents of H(2)O(2). This complex was isolated and also fully characterized by crystallography. Possible intermediates in the conversion of the monosulfinate complex (3) to the disulfonate complex (7) include complexes with mixed sulfonate/sulfenate (5) or sulfonate/sulfinate (6) ligands. Complex 5, a four-oxygen adduct of 1, was not detected, but the sulfonate/sulfinate complex (6) was isolated and characterized. The oxidation chemistry of 1 is very different from that reported for other planar cis-N(2)S(2) Ni(ii) complexes including N,N'-dimethyl-N-N'-bis(2-mecaptoethyl)-1,3-ethylenediaminato) nickel(II), (8), and N,N'-bis(mercaptoethyl)-1,5-diazacyclooctane nickel(II). To address the structural aspects of the reactivity differences, the

  19. Formate-induced inhibition of the water-oxidizing complex of photosystem II studied by EPR.

    PubMed

    Feyziev, Y M; Yoneda, D; Yoshii, T; Katsuta, N; Kawamori, A; Watanabe, Y

    2000-04-04

    The effects of various formate concentrations on both the donor and the acceptor sides in oxygen-evolving PS II membranes (BBY particles) were examined. EPR, oxygen evolution and variable chlorophyll fluorescence have been observed. It was found that formate inhibits the formation of the S(2) state multiline signal concomitant with stimulation of the Q(A)(-)Fe(2+) signal at g = 1.82. The decrease and the increase in intensities of the multiline and Q(A)(-)Fe(2+) signals, respectively, had a linear relation for formate concentrations between 5 and 500 mM. The g = 4.1 signal formation measured in the absence of methanol was not inhibited by formate up to 250 mM in the buffer. In the presence of 3% methanol the g = 4.1 signal evolved as formate concentration increased. The evolved signal could be ascribed to the inhibited centers. Oxygen evolution measured in the presence of an electron acceptor, phenyl-p-benzoquinone, was also inhibited by formate proportionally to the decrease in the multiline signal intensity. The inhibition seemed to be due to a retarded electron transfer from the water-oxidizing complex to Y(Z)(+), which was observed in the decay kinetics of the Y(Z)(+) signal induced by illumination above 250 K. These results show that formate induces inhibition of water oxidation reactions as well as electron transfer on the PS II acceptor side. The inhibition effects of formate in PS II were found to be reversible, indicating no destructive effect on the reaction center induced by formate.

  20. Requirement of kinesin-mediated membrane transport of WAVE2 along microtubules for lamellipodia formation promoted by hepatocyte growth factor.

    PubMed

    Takahashi, Kazuhide; Suzuki, Katsuo

    2008-07-01

    Lamellipodia formation necessary for epithelial cell migration and invasion is accomplished by rearrangement of the actin cytoskeleton at the leading edge through membrane transport of WAVE2. However, how WAVE2 is transported to the cell periphery where lamellipodia are formed remains to be established. We report here that hepatocyte growth factor (HGF) promoted lamellipodia formation and intracellular transport of WAVE2 to the cell periphery, depending on Rac1 activity, in MDA-MB-231 human breast cancer cells. Immunoblot analyses indicating the coimmunoprecipitation of WAVE2 with kinesin heavy chain KIF5B, one of the motor proteins, and IQGAP1 suggest that KIF5B and IQGAP1 formed a complex with WAVE2 in serum-starved cells and increased in their amount after HGF stimulation. Both downregulation of KIF5B by the small interfering RNA and depolymerization of microtubules with nocodazole abrogated the HGF-induced lamellipodia formation and WAVE2 transport. Therefore, we propose here that the promotion of lamellipodia formation by HGF in MDA-MB-231 cells is Rac1-dependent and requires KIF5B-mediated transport of WAVE2 and IQGAP1 to the cell periphery along microtubules.

  1. Paleobiology of a Neoproterozoic tidal flat/lagoonal complex: the Draken Conglomerate Formation, Spitsbergen.

    PubMed

    Knoll, A H; Swett, K; Mark, J

    1991-01-01

    Carbonates and rare shales of the ca 700-800 Ma old Draken Conglomerate Formation, northeastern Spitsbergen, preserve a record of environmental variation within a Neoproterozoic tidal flat/lagoon complex. Forty-two microfossil taxa have been recognized in Draken rocks, and of these, 39 can be characterized in terms of their paleoenvironmental distributions along a gradient from the supratidal zone to permanently submerged lagoons. Supratidal to subtidal trends include: increasing microbenthic diversity, increasing abundance and diversity of included allochthonous (presumably planktonic) elements, decreasing sheath thickness of mat-building organisms (with significant taphonomic consequences), and an increasing sediment/fossil ratio in fossiliferous rocks. Five principal and several minor biofacies can be distinguished. The paleoecological resolution obtainable in the Draken Conglomerate Formation rivals that achieved for most Phanerozoic fossil deposits. It documents the complexity and diversity of Proterozoic coastal ecosystems and indicates that both environment and taphonomy need to be taken into explicit consideration in attempts to understand evolutionary trends in early fossil record. Three species, Coniunctiophycus majorinum, Myxococcoides distola, and M. chlorelloidea, are described as new; Siphonophycus robustum, Siphonophycus septatum, and Gorgonisphaeridium maximum are proposed as new combinations.

  2. Paleobiology of a Neoproterozoic tidal flat/lagoonal complex: the Draken Conglomerate Formation, Spitsbergen

    NASA Technical Reports Server (NTRS)

    Knoll, A. H.; Swett, K.; Mark, J.

    1991-01-01

    Carbonates and rare shales of the ca 700-800 Ma old Draken Conglomerate Formation, northeastern Spitsbergen, preserve a record of environmental variation within a Neoproterozoic tidal flat/lagoon complex. Forty-two microfossil taxa have been recognized in Draken rocks, and of these, 39 can be characterized in terms of their paleoenvironmental distributions along a gradient from the supratidal zone to permanently submerged lagoons. Supratidal to subtidal trends include: increasing microbenthic diversity, increasing abundance and diversity of included allochthonous (presumably planktonic) elements, decreasing sheath thickness of mat-building organisms (with significant taphonomic consequences), and an increasing sediment/fossil ratio in fossiliferous rocks. Five principal and several minor biofacies can be distinguished. The paleoecological resolution obtainable in the Draken Conglomerate Formation rivals that achieved for most Phanerozoic fossil deposits. It documents the complexity and diversity of Proterozoic coastal ecosystems and indicates that both environment and taphonomy need to be taken into explicit consideration in attempts to understand evolutionary trends in early fossil record. Three species, Coniunctiophycus majorinum, Myxococcoides distola, and M. chlorelloidea, are described as new; Siphonophycus robustum, Siphonophycus septatum, and Gorgonisphaeridium maximum are proposed as new combinations.

  3. A hypothesis: factor VII governs clot formation, tissue repair and apoptosis.

    PubMed

    Coleman, Lewis S

    2007-01-01

    A hypothesis: thrombin is a "Universal Enzyme of Energy Transduction" that employs ATP energy in flowing blood to activate biochemical reactions and cell effects in both hemostasis and tissue repair. All cells possess PAR-1 (thrombin) receptors and are affected by thrombin elevations, and thrombin effects on individual cell types are determined by their unique complement of PAR-1 receptors. Disruption of the vascular endothelium (VE) activates a tissue repair mechanism (TRM) consisting of the VE, tissue factor (TF), and circulating Factors VII, IX and X that governs localized thrombin elevations to activate clot formation and cellular effects that repair tissue damage. The culmination of the repair process occurs with the restoration of the VE followed by declines in thrombin production that causes Apoptosis ("programmed cell death") in wound-healing fibroblasts, which functions as a mechanism to draw wound edges together. The location and magnitude of TRM activity governs the location and magnitude of Factor VIII activity and clot formation, but the large size of Factor VIII prevents it from penetrating the clot formed by its activity, so that its effects are self-limiting. Factors VII, IX and X function primarily as tissue repair enzymes, while Factor VIII and Factor XIII are the only serine protease enzymes in the "Coagulation Cascade" that are exclusively associated with hemostasis.

  4. RIPK3 regulates p62-LC3 complex formation via the caspase-8-dependent cleavage of p62.

    PubMed

    Matsuzawa, Yu; Oshima, Shigeru; Nibe, Yoichi; Kobayashi, Masanori; Maeyashiki, Chiaki; Nemoto, Yasuhiro; Nagaishi, Takashi; Okamoto, Ryuichi; Tsuchiya, Kiichiro; Nakamura, Tetsuya; Watanabe, Mamoru

    2015-01-02

    RIPK3 is a key molecule for necroptosis, initially characterized by necrotic cell death morphology and the activation of autophagy. Cell death and autophagic signaling are believed to tightly regulate each other. However, the associated recruitment of signaling proteins remains poorly understood. p62/sequestosome-1 is a selective autophagy substrate and a selective receptor for ubiquitinated proteins. In this study, we illustrated that both mouse and human RIPK3 mediate p62 cleavage and that RIPK3 interacts with p62, resulting in complex formation. In addition, RIPK3-dependent p62 cleavage is restricted by the inhibition of caspases, especially caspase-8. Moreover, overexpression of A20, a ubiquitin-editing enzyme and an inhibitor of caspase-8 activity, inhibits RIPK3-dependent p62 cleavage. To further investigate the potential role of RIPK3 in selective autophagy, we analyzed p62-LC3 complex formation, revealing that RIPK3 prevents the localization of LC3 and ubiquitinated proteins to the p62 complex. In addition, RIPK3-dependent p62-LC3 complex disruption is regulated by caspase inhibition. Taken together, these results demonstrated that RIPK3 interacts with p62 and regulates p62-LC3 complex formation. These findings suggested that RIPK3 serves as a negative regulator of selective autophagy and provides new insights into the mechanism by which RIPK3 regulates autophagic signaling. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Indices of Complexity and Interpretation: Their Computation and Uses in Factor Analysis.

    ERIC Educational Resources Information Center

    Hofmann, Richard J.

    In this methodological paper two indices are developed: a complexity index and an interpretation index. The complexity index is a positive number indicating on the average how many factors are used to explain each variable in a factor solution. The interpretation index will be positive ranging from zero to unity; unity representing a perfect…

  6. Factor complexity of crash occurrence: An empirical demonstration using boosted regression trees.

    PubMed

    Chung, Yi-Shih

    2013-12-01

    Factor complexity is a characteristic of traffic crashes. This paper proposes a novel method, namely boosted regression trees (BRT), to investigate the complex and nonlinear relationships in high-variance traffic crash data. The Taiwanese 2004-2005 single-vehicle motorcycle crash data are used to demonstrate the utility of BRT. Traditional logistic regression and classification and regression tree (CART) models are also used to compare their estimation results and external validities. Both the in-sample cross-validation and out-of-sample validation results show that an increase in tree complexity provides improved, although declining, classification performance, indicating a limited factor complexity of single-vehicle motorcycle crashes. The effects of crucial variables including geographical, time, and sociodemographic factors explain some fatal crashes. Relatively unique fatal crashes are better approximated by interactive terms, especially combinations of behavioral factors. BRT models generally provide improved transferability than conventional logistic regression and CART models. This study also discusses the implications of the results for devising safety policies. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Factors influencing efficient structure of fuel and energy complex

    NASA Astrophysics Data System (ADS)

    Sidorova, N. G.; Novikova, S. A.

    2017-10-01

    The development of the Russian fuel-energy complex is a priority for the national economic policy, and the Far East is a link between Russia and the Asia-Pacific region. Large-scale engineering of numerous resources of the Far East will force industrial development, increase living standard and strengthen Russia’s position in the global energy market. So, revealing the factors which influence rational structure of the fuel-energy complex is very urgent nowadays. With the use of depth analysis of development tendencies of the complex and its problems the authors show ways of its efficiency improvement.

  8. Interaction and formation mechanism of binary complex between zein and propylene glycol alginate.

    PubMed

    Sun, Cuixia; Dai, Lei; Gao, Yanxiang

    2017-02-10

    The anti-solvent co-precipitation method was used to fabricate the zein-propylene glycol alginate (PGA) binary complex with different mass ratios of zein to PGA (20:1, 10:1, 5:1, 2:1 and 1:1) at pH 4.0. Results showed that attractive electrostatic interaction between zein and PGA occurred and negatively charged binary complex with large size and high turbidity was formed due to the charge neutralization. Hydrogen bonding and hydrophobic effects were involved in the interactions between zein and PGA, leading to the changed secondary structure and improved thermal stability of zein. Aggregates in the irregular shape with large size were obviously observed in the AFM images. PGA alone exhibited a fine filamentous network structure, while zein-PGA binary complex showed a rough branch-like pattern and the surface of "branch" was closely adsorbed by lots of spherical zein particles. Q in zein-PGA binary complex dispersions presented the improved photochemical and thermal stability. The potential mechanism of a two-step process was proposed to explain the formation of zein-PGA binary complexes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Young stellar population and star formation history ofW4 HII region/Cluster Complex

    NASA Astrophysics Data System (ADS)

    Panwar, Neelam

    2018-04-01

    The HII region/cluster complex has been a subject of numerous investigations to study the feedback effect of massive stars on their surroundings. Massive stars not only alter the morphology of the parental molecular clouds, but also influence star formation, circumstellar disks and the mass function of low-mass stars in their vicinity. However, most of the studies of low-mass stellar content of the HII regions are limited only to the nearby regions. We study the star formation in the W4 HII region using deep optical observations obtained with the archival data from Canada - France - Hawaii Telescope, Two-Micron All Sky Survey, Spitzer, Herschel and Chandra. We investigate the spatial distribution of young stellar objects in the region, their association with the remnant molecular clouds, and search for the clustering to establish the sites of recent star formation. Our analysis suggests that the influence of massive stars on circumstellar disks is significant only to thei! r immediate neighborhood. The spatial correlation of the young stars with the distribution of gas and dust of the complex indicate that the clusters would have formed in a large filamentary cloud. The observing facilities at the 3.6-m Devasthal Optical Telescope (DOT), providing high-resolution spectral and imaging capabilities, will fulfill the major objectives in the study of HII regions.

  10. Higher platelet reactivity and platelet-monocyte complex formation in Gram-positive sepsis compared to Gram-negative sepsis.

    PubMed

    Tunjungputri, Rahajeng N; van de Heijden, Wouter; Urbanus, Rolf T; de Groot, Philip G; van der Ven, Andre; de Mast, Quirijn

    2017-09-01

    Platelets may play a role in the high risk for vascular complications in Gram-positive sepsis. We compared the platelet reactivity of 15 patients with Gram-positive sepsis, 17 with Gram-negative sepsis and 20 healthy controls using a whole blood flow cytometry-based assay. Patients with Gram-positive sepsis had the highest median fluorescence intensity (MFI) of the platelet membrane expression of P-selectin upon stimulation with high dose adenosine diphosphate (ADP; P = 0.002 vs. Gram-negative and P = 0.005 vs. control groups) and cross-linked collagen-related peptide (CRP-XL; P = 0.02 vs. Gram-negative and P = 0.0001 vs. control groups). The Gram-positive group also demonstrated significantly higher ADP-induced fibrinogen binding (P = 0.001), as wll as platelet-monocyte complex formation (P = 0.02), compared to the Gram-negative group and had the highest plasma levels of platelet factor 4, β-thromboglobulin and soluble P-selectin. In contrast, thrombin-antithrombin complex and C-reactive protein levels were comparable in both patient groups. In conclusion, common Gram-positive pathogens induce platelet hyperreactivity, which may contribute to a higher risk for vascular complications.

  11. [Indices of pigment formation in complex cytomorphological research on human pigmented skin neoplasms].

    PubMed

    Naleskina, L A

    1985-01-01

    Analysis of the topography peculiarities and distribution of oxidized melanine and its precursors (DOPA-oxide activity and catecholamine) in pigment nevuses and malignant melanomas of skin shows that the studied peculiarities are a complex of intersupplementary markers of melanine formation, correlate with the quality and the degree of proliferative process expression in tumours of this genesis and may be used for their malignancy rating.

  12. Dynamic studies of H-Ras•GTPγS interactions with nucleotide exchange factor Sos reveal a transient ternary complex formation in solution

    PubMed Central

    Vo, Uybach; Vajpai, Navratna; Embrey, Kevin J.; Golovanov, Alexander P.

    2016-01-01

    The cycling between GDP- and GTP- bound forms of the Ras protein is partly regulated by the binding of Sos. The structural/dynamic behavior of the complex formed between activated Sos and Ras at the point of the functional cycle where the nucleotide exchange is completed has not been described to date. Here we show that solution NMR spectra of H-Ras∙GTPγS mixed with a functional fragment of Sos (SosCat) at a 2:1 ratio are consistent with the formation of a rather dynamic assembly. H-Ras∙GTPγS binding was in fast exchange on the NMR timescale and retained a significant degree of molecular tumbling independent of SosCat, while SosCat also tumbled largely independently of H-Ras. Estimates of apparent molecular weight from both NMR data and SEC-MALS revealed that, at most, only one H-Ras∙GTPγS molecule appears stably bound to Sos. The weak transient interaction between Sos and the second H-Ras∙GTPγS may provide a necessary mechanism for complex dissociation upon the completion of the native GDP → GTP exchange reaction, but also explains measurable GTP → GTP exchange activity of Sos routinely observed in in vitro assays that use fluorescently-labelled analogs of GTP. Overall, the data presents the first dynamic snapshot of Ras functional cycle as controlled by Sos. PMID:27412770

  13. Dynamic studies of H-Ras•GTPγS interactions with nucleotide exchange factor Sos reveal a transient ternary complex formation in solution.

    PubMed

    Vo, Uybach; Vajpai, Navratna; Embrey, Kevin J; Golovanov, Alexander P

    2016-07-14

    The cycling between GDP- and GTP- bound forms of the Ras protein is partly regulated by the binding of Sos. The structural/dynamic behavior of the complex formed between activated Sos and Ras at the point of the functional cycle where the nucleotide exchange is completed has not been described to date. Here we show that solution NMR spectra of H-Ras∙GTPγS mixed with a functional fragment of Sos (Sos(Cat)) at a 2:1 ratio are consistent with the formation of a rather dynamic assembly. H-Ras∙GTPγS binding was in fast exchange on the NMR timescale and retained a significant degree of molecular tumbling independent of Sos(Cat), while Sos(Cat) also tumbled largely independently of H-Ras. Estimates of apparent molecular weight from both NMR data and SEC-MALS revealed that, at most, only one H-Ras∙GTPγS molecule appears stably bound to Sos. The weak transient interaction between Sos and the second H-Ras∙GTPγS may provide a necessary mechanism for complex dissociation upon the completion of the native GDP → GTP exchange reaction, but also explains measurable GTP → GTP exchange activity of Sos routinely observed in in vitro assays that use fluorescently-labelled analogs of GTP. Overall, the data presents the first dynamic snapshot of Ras functional cycle as controlled by Sos.

  14. Formation of stable nanoparticles via electrostatic complexation between sodium caseinate and gum arabic.

    PubMed

    Ye, Aiqian; Flanagan, John; Singh, Harjinder

    2006-06-05

    The formation of electrostatic complexes between sodium caseinate and gum arabic (GA) was studied as a function of pH (2.0-7.0), using slow acidification in situ with glucono-delta-lactone (GDL) or titration with HCl. The colloidal behavior of the complexes under specific conditions was investigated using absorbance measurements (at 515 or 810 nm) and dynamic light scattering (DLS). In contrast to the sudden increase in absorbance and subsequent precipitation of sodium caseinate solutions at pH < 5.4, the absorbance values of mixtures of sodium caseinate and GA increased to a level that was dependent on GA concentration at pH 5.4 (pH(c)). The absorbance values remained constant with further decreases in pH until a sudden increase in absorbance was observed (at pH(phi)). The pH(phi) was also dependent upon the GA concentration. Dynamic light scattering (DLS) data showed that the sizes of the particles formed by the complexation of sodium caseinate and GA between pH(c) and pH(phi) were between 100 and 150 nm and these nanoparticles were visualized using negative staining transmission electron microscopy (TEM). Below pH(phi), the nanoparticles associated to form larger particles, causing phase separation. zeta-Potential measurements of the nanoparticles and chemical analysis after phase separation showed that phase separation was a consequence of charge neutralization. The formation of complexes between sodium caseinate and GA was inhibited at high ionic strength (>50 mM NaCl). It is postulated that the structure of the nanoparticles comprises an aggregated caseinate core, protected from further aggregation by steric repulsion of one, or more, electrostatically attached GA molecules. Copyright 2005 Wiley Periodicals, Inc.

  15. Mechanisms of Host-Pathogen Protein Complex Formation and Bacterial Immune Evasion of Streptococcus suis Protein Fhb.

    PubMed

    Li, Xueqin; Liu, Peng; Gan, Shuzhen; Zhang, Chunmao; Zheng, Yuling; Jiang, Yongqiang; Yuan, Yuan

    2016-08-12

    Streptococcus suis serotype 2 (S. suis 2)-induced sepsis and meningitis are often accompanied by bacteremia. The evasion of polymorphonuclear leukocyte-mediated phagocytic clearance is central to the establishment of bacteremia caused by S. suis 2 and is facilitated by the ability of factor H (FH)-binding protein (Fhb) to bind FH on the bacterial surface, thereby impeding alternative pathway complement activation and phagocytic clearance. Here, C3b/C3d was found to bind to Fhb, along with FH, forming a large immune complex. The formation of this immune complex was mediated by domain II of Fhb via electrostatic and hydrophobic interactions, which, to our knowledge, is a new type of interaction. Interestingly, Fhb was found to be associated with the cell envelope and also present in the culture supernatant, where secreted Fhb inhibited complement activation via interactions with domain II, thereby enhancing antiphagocytic clearance by polymorphonuclear leukocytes. Thus, Fhb is a multifunctional bacterial protein, which binds host complement component C3 as well as FH and interferes with innate immune recognition in a secret protein manner. S. suis 2 therefore appears to have developed a new strategy to combat host innate immunity and enhance survival in host blood. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Mechanisms of Host-Pathogen Protein Complex Formation and Bacterial Immune Evasion of Streptococcus suis Protein Fhb*

    PubMed Central

    Li, Xueqin; Liu, Peng; Gan, Shuzhen; Zhang, Chunmao; Zheng, Yuling; Jiang, Yongqiang; Yuan, Yuan

    2016-01-01

    Streptococcus suis serotype 2 (S. suis 2)-induced sepsis and meningitis are often accompanied by bacteremia. The evasion of polymorphonuclear leukocyte-mediated phagocytic clearance is central to the establishment of bacteremia caused by S. suis 2 and is facilitated by the ability of factor H (FH)-binding protein (Fhb) to bind FH on the bacterial surface, thereby impeding alternative pathway complement activation and phagocytic clearance. Here, C3b/C3d was found to bind to Fhb, along with FH, forming a large immune complex. The formation of this immune complex was mediated by domain II of Fhb via electrostatic and hydrophobic interactions, which, to our knowledge, is a new type of interaction. Interestingly, Fhb was found to be associated with the cell envelope and also present in the culture supernatant, where secreted Fhb inhibited complement activation via interactions with domain II, thereby enhancing antiphagocytic clearance by polymorphonuclear leukocytes. Thus, Fhb is a multifunctional bacterial protein, which binds host complement component C3 as well as FH and interferes with innate immune recognition in a secret protein manner. S. suis 2 therefore appears to have developed a new strategy to combat host innate immunity and enhance survival in host blood. PMID:27342778

  17. Interdependency of formation and localisation of the Min complex controls symmetric plastid division.

    PubMed

    Maple, Jodi; Møller, Simon G

    2007-10-01

    Plastid division represents a fundamental biological process essential for plant development; however, the molecular basis of symmetric plastid division is unclear. AtMinE1 plays a pivotal role in selection of the plastid division site in concert with AtMinD1. AtMinE1 localises to discrete foci in chloroplasts and interacts with AtMinD1, which shows a similar localisation pattern. Here, we investigate the importance of Min protein complex formation during the chloroplast division process. Dissection of the assembly of the Min protein complex and determination of the interdependency of complex assembly and localisation in planta allow us to present a model of the molecular basis of selection of the division site in plastids. Moreover, functional analysis of AtMinE1 in bacteria demonstrates the level of functional conservation and divergence of the plastidic MinE proteins.

  18. Reductive Elimination Leading to C-C Bond Formation in Gold(III) Complexes: A Mechanistic and Computational Study.

    PubMed

    Rocchigiani, Luca; Fernandez-Cestau, Julio; Budzelaar, Peter H M; Bochmann, Manfred

    2018-06-21

    The factors affecting the rates of reductive C-C cross-coupling reactions in gold(III) aryls were studied by using complexes that allow easy access to a series of electronically modified aryl ligands, as well as to gold methyl and vinyl complexes, by using the pincer compounds [(C^N^C)AuR] (R=C 6 F 5 , CH=CMe 2 , Me and p-C 6 H 4 X, where X=OMe, F, H, tBu, Cl, CF 3 , or NO 2 ) as starting materials (C^N^C=2,6-(4'-tBuC 6 H 3 ) 2 pyridine dianion). Protodeauration followed by addition of one equivalent SMe 2 leads to the quantitative generation of the thioether complexes [(C^N-CH)AuR(SMe 2 )] + . Upon addition of a second SMe 2 pyridine is displaced, which triggers the reductive aryl-R elimination. The rates for these cross-couplings increase in the sequence k(vinyl)>k(aryl)≫k(C 6 F 5 )>k(Me). Vinyl-aryl coupling is particularly fast, 1.15×10 -3  L mol -1  s -1 at 221 K, whereas both C 6 F 5 and Me couplings encountered higher barriers for the C-C bond forming step. The use of P(p-tol) 3 in place of SMe 2 greatly accelerates the C-C couplings. Computational modelling shows that in the C^N-bonded compounds displacement of N by a donor L is required before the aryl ligands can adopt a conformation suitable for C-C bond formation, so that elimination takes place from a four-coordinate intermediate. The C-C bond formation is the rate-limiting step. In the non-chelating case, reductive C(sp 2 )-C(sp 2 ) elimination from three-coordinate ions [(Ar 1 )(Ar 2 )AuL] + is almost barrier-free, particularly if L=phosphine. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A Biomimetic Nickel Complex with a Reduced CO2 Ligand Generated by Formate Deprotonation and Its Behaviour towards CO2.

    PubMed

    Zimmermann, Philipp; Hoof, Santina; Braun-Cula, Beatrice; Herwig, Christian; Limberg, Christian

    2018-04-10

    Reduced CO 2 species are key intermediates in a variety of natural and synthetic processes. In the majority of systems, however, they elude isolation or characterisation owing to high reactivity or limited accessibility (heterogeneous systems), and their formulations thus often remain uncertain or are based on calculations only. We herein report on a Ni-CO 2 2- complex that is unique in many ways. While its structural and electronic features help understand the CO 2 -bound state in Ni,Fe carbon monoxide dehydrogenases, its reactivity sheds light on how CO 2 can be converted into CO/CO 3 2- by nickel complexes. In addition, the complex was generated by a rare example of formate β-deprotonation, a mechanistic step relevant to the nickel-catalysed conversion of H x CO y z- at electrodes and formate oxidation in formate dehydrogenases. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Regulation of Botulinum Neurotoxin Synthesis and Toxin Complex Formation by Arginine and Glucose in Clostridium botulinum ATCC 3502.

    PubMed

    Fredrick, Chase M; Lin, Guangyun; Johnson, Eric A

    2017-07-01

    Botulinum neurotoxin (BoNT), produced by neurotoxigenic clostridia, is the most potent biological toxin known and the causative agent of the paralytic disease botulism. The nutritional, environmental, and genetic regulation of BoNT synthesis, activation, stability, and toxin complex (TC) formation is not well studied. Previous studies indicated that growth and BoNT formation were affected by arginine and glucose in Clostridium botulinum types A and B. In the present study, C. botulinum ATCC 3502 was grown in toxin production medium (TPM) with different levels of arginine and glucose and of three products of arginine metabolism, citrulline, proline, and ornithine. Cultures were analyzed for growth (optical density at 600 nm [OD 600 ]), spore formation, and BoNT and TC formation by Western blotting and immunoprecipitation and for BoNT activity by mouse bioassay. A high level of arginine (20 g/liter) repressed BoNT production approximately 1,000-fold, enhanced growth, slowed lysis, and reduced endospore production by greater than 1,000-fold. Similar effects on toxin production were seen with equivalent levels of citrulline but not ornithine or proline. In TPM lacking glucose, levels of formation of BoNT/A1 and TC were significantly decreased, and extracellular BoNT and TC proteins were partially inactivated after the first day of culture. An understanding of the regulation of C. botulinum growth and BoNT and TC formation should be valuable in defining requirements for BoNT formation in foods and clinical samples, improving the quality of BoNT for pharmaceutical preparations, and elucidating the biological functions of BoNTs for the bacterium. IMPORTANCE Botulinum neurotoxin (BoNT) is a major food safety and bioterrorism concern and is also an important pharmaceutical, and yet the regulation of its synthesis, activation, and stability in culture media, foods, and clinical samples is not well understood. This paper provides insights into the effects of critical

  1. Spectral Studies of Iron Coordination in Hemeprotein Complexes

    PubMed Central

    Brill, Arthur S.; Sandberg, Howard E.

    1968-01-01

    In order to evaluate the feasibility of observing the spectral behavior of protein groups in the coordination sphere of the iron in hemeproteins, criteria are developed to determine whether or not the application of difference absorption spectroscopy to the study of complex formation will be successful. Absolute absorption spectra, 300-1100 mμ, from bacterial catalase complexes are displayed, and the infrared bands correlated with magnetic susceptibility values of similar complexes of other hemeproteins. Dissociation constants for the formation of cyanide and azide complexes of metmyoglobin, methemoglobin, bacterial catalase, and horseradish peroxidase are given. Difference spectra, 210-280 mμ, are displayed for cyanide and azide complexes of these hemeproteins. A band at 235-241 mμ is found in the difference spectra of all low-spin vs. high-spin complexes. The factors which favor the assignment of this band to a transition involving a histidine residue are presented. PMID:5699802

  2. Constructing the tree-level Yang-Mills S-matrix using complex factorization

    NASA Astrophysics Data System (ADS)

    Schuster, Philip C.; Toro, Natalia

    2009-06-01

    A remarkable connection between BCFW recursion relations and constraints on the S-matrix was made by Benincasa and Cachazo in 0705.4305, who noted that mutual consistency of different BCFW constructions of four-particle amplitudes generates non-trivial (but familiar) constraints on three-particle coupling constants — these include gauge invariance, the equivalence principle, and the lack of non-trivial couplings for spins > 2. These constraints can also be derived with weaker assumptions, by demanding the existence of four-point amplitudes that factorize properly in all unitarity limits with complex momenta. From this starting point, we show that the BCFW prescription can be interpreted as an algorithm for fully constructing a tree-level S-matrix, and that complex factorization of general BCFW amplitudes follows from the factorization of four-particle amplitudes. The allowed set of BCFW deformations is identified, formulated entirely as a statement on the three-particle sector, and using only complex factorization as a guide. Consequently, our analysis based on the physical consistency of the S-matrix is entirely independent of field theory. We analyze the case of pure Yang-Mills, and outline a proof for gravity. For Yang-Mills, we also show that the well-known scaling behavior of BCFW-deformed amplitudes at large z is a simple consequence of factorization. For gravity, factorization in certain channels requires asymptotic behavior ~ 1/z2.

  3. Formation of Polyelectrolyte Complex Colloid Particles between Chitosan and Pectin with Different Degree of Esterification

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Sun, Hongyuan; He, Jieyu

    2017-12-01

    The effects of degree of esterification, pectin/chitosan ratio and pH on the formation of polyelectrolyte complex colloid particles between chitosan (CS) and pectin (PE) were investigated. Low methoxyl pectin (LPE) was achieved by de-esterifying high methoxyl pectin (HPE) with pectin methyl esterase. Turbidity titration and colorimetric method was used to determine the stability of complex colloid particles. The structure and morphology of complex particles were characterized by FTIR and TEM. When pectin solution was dropped into chitosan solution, complex colloidal dispersion was stable as PE/CS mass ratio was no more than 3:2. Colloidal particles of HPE-CS complex coagulated at larger ratio of PE/CS than LPE-CS. The maximum complex occurred at pH 6.1 for HPE-CS and pH 5.7 for LPE-CS, and decreasing pH leaded to the dissociation of complex particles. Electrostatic interactions between carboxyl groups on pectin and amino groups on chitosan were confirmed by FTIR. Colloidal particle sizes ranged from about 100 nm to 400 nm with spherical shape.

  4. Hair dye-incorporated poly-γ-glutamic acid/glycol chitosan nanoparticles based on ion-complex formation.

    PubMed

    Lee, Hye-Young; Jeong, Young-Il; Choi, Ki-Choon

    2011-01-01

    p-Phenylenediamine (PDA) or its related chemicals are used more extensively than oxidative hair dyes. However, permanent hair dyes such as PDA are known to have potent contact allergy reactions in humans, and severe allergic reactions are problematic. PDA-incorporated nanoparticles were prepared based on ion-complex formation between the cationic groups of PDA and the anionic groups of poly(γ-glutamic acid) (PGA). To reinforce PDA/PGA ion complexes, glycol chitosan (GC) was added. PDA-incorporated nanoparticles were characterized using field-emission scanning electron microscopy, Fourier- transform infrared (FT-IR) spectroscopy, dynamic light scattering, and powder X-ray diffractometry (XRD). Nanoparticles were formed by ion-complex formation between the amine groups of PDA and the carboxyl groups of PGA. PDA-incorporated nanoparticles are small in size (<100 nm), and morphological observations showed spherical shapes. FT-IR spectra results showed that the carboxylic acid peak of PGA decreased with increasing PDA content, indicating that the ion complexes were formed between the carboxyl groups of PGA and the amine groups of PDA. Furthermore, the intrinsic peak of the carboxyl groups of PGA was also decreased by the addition of GC. Intrinsic crystalline peaks of PDA were observed by XRD. This crystalline peak of PDA was completely nonexistent when nanoparticles were formed by ion complex between PDA, PGA, and GC, indicating that PDA was complexed with PGA and no free drug existed in the formulation. During the drug-release experiment, an initial burst release of PDA was observed, and then PDA was continuously released over 1 week. Cytotoxicity testing against HaCaT human skin keratinocyte cells showed PDA-incorporated nanoparticles had lower toxicity than PDA itself. Furthermore, PDA-incorporated nanoparticles showed reduced apoptosis and necrosis reaction at HaCaT cells. The authors suggest that these microparticles are ideal candidates for a vehicle for

  5. K6 linked polyubiquitylation of FADD by CHIP prevents death inducing signaling complex formation suppressing cell death.

    PubMed

    Seo, Jinho; Lee, Eun-Woo; Shin, Jihye; Seong, Daehyeon; Nam, Young Woo; Jeong, Manhyung; Lee, Seon-Hyeong; Lee, Cheolju; Song, Jaewhan

    2018-05-23

    Fas-associated death domain (FADD) is an adaptor protein recruiting complexes of caspase 8 to death ligand receptors to induce extrinsic apoptotic cell death in response to a TNF superfamily member. Although, formation of the complex of FADD and caspase 8 upon death stimuli has been studied in detail, posttranslational modifications fine-tuning these processes have yet to be identified. Here we revealed that K6-linked polyubiquitylation of FADD on lysines 149 and 153 mediated by C terminus HSC70-interacting protein (CHIP) plays an important role in preventing formation of the death inducing signaling complex (DISC), thus leading to the suppression of cell death. Cells depleted of CHIP showed higher sensitivity toward death ligands such as FasL and TRAIL, leading to upregulation of DISC formation composed of a death receptor, FADD, and caspase 8. CHIP was able to bind to FADD, induce K6-linked polyubiquitylation of FADD, and suppress DISC formation. By mass spectrometry, lysines 149 and 153 of FADD were found to be responsible for CHIP-mediated FADD ubiquitylation. FADD mutated at these sites was capable of more potent cell death induction as compared with the wild type and was no longer suppressed by CHIP. On the other hand, CHIP deficient in E3 ligase activity was not capable of suppressing FADD function and of FADD ubiquitylation. CHIP depletion in ME-180 cells induced significant sensitization of these cells toward TRAIL in xenograft analyses. These results imply that K6-linked ubiquitylation of FADD by CHIP is a crucial checkpoint in cytokine-dependent extrinsic apoptosis.

  6. Recent progress in biopolymer nanoparticle and microparticle formation by heat-treating electrostatic protein-polysaccharide complexes.

    PubMed

    Jones, Owen G; McClements, David Julian

    2011-09-14

    Functional biopolymer nanoparticles or microparticles can be formed by heat treatment of globular protein-ionic polysaccharide electrostatic complexes under appropriate solution conditions. These biopolymer particles can be used as encapsulation and delivery systems, fat mimetics, lightening agents, or texture modifiers. This review highlights recent progress in the design and fabrication of biopolymer particles based on heating globular protein-ionic polysaccharide complexes above the thermal denaturation temperature of the proteins. The influence of biopolymer type, protein-polysaccharide ratio, pH, ionic strength, and thermal history on the characteristics of the biopolymer particles formed is reviewed. Our current understanding of the underlying physicochemical mechanisms of particle formation and properties is given. The information provided in this review should facilitate the rational design of biopolymer particles with specific physicochemical and functional attributes, as well as stimulate further research in identifying the physicochemical origin of particle formation. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Determination of complex formation constants by phase sensitive alternating current polarography: Cadmium-polymethacrylic acid and cadmium-polygalacturonic acid.

    PubMed

    Garrigosa, Anna Maria; Gusmão, Rui; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

    2007-10-15

    The use of phase sensitive alternating current polarography (ACP) for the evaluation of complex formation constants of systems where electrodic adsorption is present has been proposed. The applicability of the technique implies the previous selection of the phase angle where contribution of capacitive current is minimized. This is made using Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) in the analysis of ACP measurements at different phase angles. The method is checked by the study of the complexation of Cd by polymethacrylic (PMA) and polygalacturonic (PGA) acids, and the optimal phase angles have been ca. -10 degrees for Cd-PMA and ca. -15 degrees for Cd-PGA systems. The goodness of phase sensitive ACP has been demonstrated comparing the determined complex formation constants with those obtained by reverse pulse polarography, a technique that minimizes the electrode adsorption effects on the measured currents.

  8. BAG3 regulates formation of the SNARE complex and insulin secretion

    PubMed Central

    Iorio, V; Festa, M; Rosati, A; Hahne, M; Tiberti, C; Capunzo, M; De Laurenzi, V; Turco, M C

    2015-01-01

    Insulin release in response to glucose stimulation requires exocytosis of insulin-containing granules. Glucose stimulation of beta cells leads to focal adhesion kinase (FAK) phosphorylation, which acts on the Rho family proteins (Rho, Rac and Cdc42) that direct F-actin remodeling. This process requires docking and fusion of secretory vesicles to the release sites at the plasma membrane and is a complex mechanism that is mediated by SNAREs. This transiently disrupts the F-actin barrier and allows the redistribution of the insulin-containing granules to more peripheral regions of the β cell, hence facilitating insulin secretion. In this manuscript, we show for the first time that BAG3 plays an important role in this process. We show that BAG3 downregulation results in increased insulin secretion in response to glucose stimulation and in disruption of the F-actin network. Moreover, we show that BAG3 binds to SNAP-25 and syntaxin-1, two components of the t-SNARE complex preventing the interaction between SNAP-25 and syntaxin-1. Upon glucose stimulation BAG3 is phosphorylated by FAK and dissociates from SNAP-25 allowing the formation of the SNARE complex, destabilization of the F-actin network and insulin release. PMID:25766323

  9. Protein Kinase Cδ and Calmodulin Regulate Epidermal Growth Factor Receptor Recycling from Early Endosomes through Arp2/3 Complex and Cortactin

    PubMed Central

    Lladó, Anna; Timpson, Paul; Vilà de Muga, Sandra; Moretó, Jemina; Pol, Albert; Grewal, Thomas; Daly, Roger J.

    2008-01-01

    The intracellular trafficking of the epidermal growth factor receptor (EGFR) is regulated by a cross-talk between calmodulin (CaM) and protein kinase Cδ (PKCδ). On inhibition of CaM, PKCδ promotes the formation of enlarged early endosomes and blocks EGFR recycling and degradation. Here, we show that PKCδ impairs EGFR trafficking due to the formation of an F-actin coat surrounding early endosomes. The PKCδ-induced polymerization of actin is orchestrated by the Arp2/3 complex and requires the interaction of cortactin with PKCδ. Accordingly, inhibition of actin polymerization by using cytochalasin D or by overexpression of active cofilin, restored the normal morphology of the organelle and the recycling of EGFR. Similar results were obtained after down-regulation of cortactin and the sequestration of the Arp2/3 complex. Furthermore we demonstrate an interaction of cortactin with CaM and PKCδ, the latter being dependent on CaM inhibition. In summary, this study provides the first evidence that CaM and PKCδ organize actin dynamics in the early endosomal compartment, thereby regulating the intracellular trafficking of EGFR. PMID:17959830

  10. Complex formation of sericoside with hydrophilic cyclodextrins: improvement of solubility and skin penetration in topical emulsion based formulations.

    PubMed

    Rode, T; Frauen, M; Müller, B W; Düsing, H J; Schönrock, U; Mundt, C; Wenck, H

    2003-03-01

    The main objective of this study was to devise novel methods for improving the solubility of the anti-inflammatory triterpenoid sericoside, the main component of Terminalia sericea extract, thus enabling its incorporation into topical formulations. Sericoside was stabilized by complex formation with hydrophilic derivatives of beta- and gamma-cyclodextrins in a molar ratio of 1.0:1.1. The complex of extract and cyclodextrin was equilibrated in water at 25 degrees C for approximately 24 h. The dehydrated complexes of T. sericea extract and cyclodextrin were characterized by differential scanning calorimetry, thermogravimetry analysis and X-ray diffraction. Complex formation with beta-cyclodextrin as well as gamma-cyclodextrin derivatives was detectable using these three analytical tools; however, only complexes with gamma-cyclodextrin derivatives showed stability upon storage after incorporation into topical o/w or w/o formulations. Furthermore, a T. sericea extract/gamma-cyclodextrin complex incorporated in an o/w formulation resulted in a 2.6-fold higher percutaneous penetration of sericoside in in vitro excised pig skin as compared to pure T. sericea extract. For the first time, the virtually insoluble anti-inflammatory active sericoside was incorporated into a topical emulsion based formulation in a stable manner, resulting in efficient skin penetration. Copyright 2003 Elsevier Science B.V.

  11. Thermodynamics of formation for the 18-crown-6-triglycine molecular complex in water-dimethylsulfoxide solvents

    NASA Astrophysics Data System (ADS)

    Usacheva, T. R.; Lan, Pham Thi; Sharnin, V. A.

    2014-06-01

    The effect of a water-dimethylsulfoxide (DMSO) solvent on the formation of a molecular complex of 18-crown-6 (18C6) with triglycine (diglycylglycine, 3Gly) is studied via calorimetric titration. It is found that switching from water to an H2O-DMSO mixture with DMSO mole fraction of 0.30 is accompanied by a monotonic increase in the stability of [3Gly18C6] complex, from log K ∘ = 1.10 to log K ∘ = 2.44, and an increase in the exothermicity of the reaction of its formation, from -5.9 to -16.9 kJ/mol. It is shown that the [3Gly18C6] complex exhibits enthalpy stabilization with negative values of enthalpy and entropy over the investigated range of H2O-DMSO solvents. Analysis of the reagents' solvation characteristics reveals that the increase in the reaction's exothermicity of transfer is due to differences in the solvation of [3Gly18C6] and 18C6 with a small solvation contribution from 3Gly. It is concluded that the change in the Gibbs energy of the reaction 3Glysolv + 18C6solv ↔ [3Gly18C6]solv is due to differences in the change in the solvation state of the complex and the peptide (Δtr G ∘([3Gly18C6])-Δtr G ∘(3Gly)).

  12. Internal and External Factors Affecting Teachers' Adoption of Formative Assessment to Support Learning

    ERIC Educational Resources Information Center

    Izci, Kemal

    2016-01-01

    Assessment forms an important part of instruction. Assessment that aims to support learning is known as formative assessment and it contributes student's learning gain and motivation. However, teachers rarely use assessment formatively to aid their students' learning. Thus reviewing the factors that limit or support teachers' practices of…

  13. Internal and External Factors Affecting Teachers' Adoption of Formative Assessment to Support Learning

    ERIC Educational Resources Information Center

    Izci, Kemal

    2016-01-01

    Assessment forms an important part of instruction. Assessment that aims to support learning is known as formative assessment and it contributes student's learning gain and motivation. However, teachers rarely use assessment formatively to aid their students' learning. Thus, reviewing the factors that limit or support teachers' practices of…

  14. Selective Reduction of CO2 to a Formate Equivalent with Heterobimetallic Gold- - -Copper Hydride Complexes.

    PubMed

    Hicken, Alexandra; White, Andrew J P; Crimmin, Mark R

    2017-11-20

    A series of heterobimetallic complexes containing three-center, two-electron Au-H-Cu bonds have been prepared from addition of a parent gold hydride to a bent d 10 copper(I) fragment. These highly unusual heterobimetallic complexes represent a missing link in the widely investigated series of neutral and cationic coinage metal hydride complexes containing Cu-H-Cu and M-H-M + moieties (M=Cu, Ag). The well-defined heterobimetallic hydride complexes act as precatalysts for the conversion of CO 2 into HCO 2 Bpin with HBpin as the reductant. The selectivity of the heterobimetallic complexes for the catalytic production of a formate equivalent surpasses that of the parent monomeric Group 11 complexes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Tectonic control of complex slope failures in the Ameka River Valley (Lower Gibe Area, central Ethiopia): Implications for landslide formation

    NASA Astrophysics Data System (ADS)

    Kycl, Petr; Rapprich, Vladislav; Verner, Kryštof; Novotný, Jan; Hroch, Tomáš; Mišurec, Jan; Eshetu, Habtamu; Tadesse Haile, Ezra; Alemayehu, Leta; Goslar, Tomasz

    2017-07-01

    Even though major faults represent important landslide controlling factors, the role the tectonic setting in actively spreading rifts plays in the development of large complex landslides is seldom discussed. The Ameka complex landslide area is located on the eastern scarp of the Gibe Gorge, approximately 45 km to the west of the Main Ethiopian Rift and 175 km to the southwest of Addis Ababa. Investigation of the complex landslide failures required a combination of satellite and airborne data-based geomorphology, geological field survey complemented with structural analysis, radiocarbon geochronology and vertical electric sounding. The obtained observations confirmed the multiphase evolution of the landslide area. We have documented that, apart from climatic and lithological conditions, the main triggering factor of the Ameka complex landslide is the tectonic development of this area. The E-W extension along the NNE-SSW trending Main Ethiopian Rift is associated with the formation of numerous parallel normal faults, such as the Gibe Gorge fault and the almost perpendicular scissor faults. The geometry of the slid blocks of coherent lithology have inherited the original tectonic framework, which suggests the crucial role tectonics play in the fragmentation of the compact rock-masses, and the origin and development of the Ameka complex landslide area. Similarly, the main scarps were also parallel to the principal tectonic features. The local tectonic framework is dominated by faults of the same orientation as the regional structures of the Main Ethiopian Rift. Such parallel tectonic frameworks display clear links between the extension of the Main Ethiopian Rift and the tectonic development of the landslide area. The Ameka complex landslide developed in several episodes over thousands of years. According to the radiocarbon data, the last of the larger displaced blocks (representing only 2% of the total area) most likely slid down in the seventh century AD. The main

  16. Deferasirox-Iron Complex Formation Ratio as an Indicator of Long-term Chelation Efficacy in β-Thalassemia Major.

    PubMed

    Lu, Meng-Yao; Lin, Ting-Hao; Chiang, Po-Hung; Kuo, Pei-Hsin; Wang, Ning; Wu, Wen-Hsin; Lin, Kai-Hsin; Wu, Tzu-Hua

    2017-04-01

    β-Thalassemia major patients with higher total drug levels [deferasirox (DEFR) plus its iron complex] do not yield better serum ferritin (SF) control. This study aimed to determine the concentrations of DEFR and its iron complex (Fe-[DEFR]2) in thalassemia patients to predict the chelation efficacy in terms of SF and cardiac T2* values. Patients' steady-state drug levels at trough (Ctrough) and 2 hours postdose (C2h) were determined. Because iron deposition may cause changes in the hepatic metabolism of amino acids, the concentrations of 40 amino acids in plasma were also assayed at 2 hours postdose. A total of 28 patients either dosing daily or twice daily were recruited. After a 1-month DEFR maintenance therapy, 38.8% and 30% of patients from groups of once-daily and twice-daily, respectively, had a plasma DEFR-iron complex formation ratio higher than 0.05 [High Chelation Ratio, (HCR)]. After a 6-month follow-up, those patients who had a HCR (n = 10) at C2h showed more favorable median changes in SF and cardiac T2* values (-388.0, +10.1) than those with a low DEFR-iron complex formation ratio (Low Chelation Ratio; n = 18; +10.5; +4.5) compared with the baseline. The levels of plasma L-arginine, L-alanine, L-glycine, L-norleucine, and L-serine were significantly lower in patients with the low Chelation Ratio condition than the levels in HCR patients. This therapeutic drug monitoring study revealed that a DEFR-iron complex formation ratio at C2h might be an applicable indicator of the efficacy of long-term DEFR iron chelation therapy. A better iron-control response to DEFR was observed in the patients with HCRs. The trends for the ratio might have value in dose-setting and need to be validated in a larger cohort.

  17. Radiation increases the cellular uptake of exosomes through CD29/CD81 complex formation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hazawa, Masaharu; Tomiyama, Kenichi; Saotome-Nakamura, Ai

    Highlights: • Radiation increases cellular uptake of exosomes. • Radiation induces colocalization of CD29 and CD81. • Exosomes selectively bind the CD29/CD81 complex. • Radiation increases the cellular uptake of exosomes through CD29/CD81 complex formation. - Abstract: Exosomes mediate intercellular communication, and mesenchymal stem cells (MSC) or their secreted exosomes affect a number of pathophysiologic states. Clinical applications of MSC and exosomes are increasingly anticipated. Radiation therapy is the main therapeutic tool for a number of various conditions. The cellular uptake mechanisms of exosomes and the effects of radiation on exosome–cell interactions are crucial, but they are not well understood.more » Here we examined the basic mechanisms and effects of radiation on exosome uptake processes in MSC. Radiation increased the cellular uptake of exosomes. Radiation markedly enhanced the initial cellular attachment to exosomes and induced the colocalization of integrin CD29 and tetraspanin CD81 on the cell surface without affecting their expression levels. Exosomes dominantly bound to the CD29/CD81 complex. Knockdown of CD29 completely inhibited the radiation-induced uptake, and additional or single knockdown of CD81 inhibited basal uptake as well as the increase in radiation-induced uptake. We also examined possible exosome uptake processes affected by radiation. Radiation-induced changes did not involve dynamin2, reactive oxygen species, or their evoked p38 mitogen-activated protein kinase-dependent endocytic or pinocytic pathways. Radiation increased the cellular uptake of exosomes through CD29/CD81 complex formation. These findings provide essential basic insights for potential therapeutic applications of exosomes or MSC in combination with radiation.« less

  18. Formation mechanism and biological activity of novel thiolated human-like collagen iron complex.

    PubMed

    Zhu, Chenhui; Liu, Lingyun; Deng, Jianjun; Ma, Xiaoxuan; Hui, Junfeng; Fan, Daidi

    2016-03-01

    To develop an iron supplement that is effectively absorbed and utilized, thiolated human-like collagen was created to improve the iron binding capacity of human-like collagen. A thiolated human-like collagen-iron complex was prepared in a phosphate buffer, and one mole of thiolated human-like collagen-iron possessed approximately 28.83 moles of iron. The characteristics of thiolated human-like collagen-iron were investigated by ultraviolet-visible absorption spectroscopy, Fourier transform infrared spectroscopy, circular dichroism, and differential scanning calorimetry. The results showed that the thiolated human-like collagen-iron complex retained the secondary structure of human-like collagen and had greater thermodynamic stability than human-like collagen, although interactions between iron ions and human-like collagen occurred during the formation of the complex. In addition, to evaluate the bioavailability of thiolated human-like collagen-iron, an in vitro Caco-2 cell model and an in vivo iron deficiency anemia mouse model were employed. The data demonstrated that the thiolated human-like collagen-iron complex exhibited greater bioavailability and was more easily utilized than FeSO4, ferric ammonium citrate, or ferrous glycinate. These results indicated that the thiolated human-like collagen-iron complex is a potential iron supplement in the biomedical field. © The Author(s) 2016.

  19. Genetic evidence suggests that GIS functions downstream of TCL1 to regulate trichome formation in Arabidopsis.

    PubMed

    Zhang, Na; Yang, Li; Luo, Sha; Wang, Xutong; Wang, Wei; Cheng, Yuxin; Tian, Hainan; Zheng, Kaijie; Cai, Ling; Wang, Shucai

    2018-04-13

    Trichome formation in Arabidopsis is regulated by a MBW complex formed by MYB, bHLH and WD40 transcriptional factors, which can activate GLABRA2 (GL2) and the R3 MYB transcription factor genes. GL2 promotes trichome formation, whereas R3 MYBs are able to block the formation of the MBW complex. It has been reported that the C2H2 transcription factor GIS (GLABROUS INFLORESCENCE STEMS) functions upstream of the MBW activator complex to regulate trichome formation, and that the expression of TCL1 is not regulated by the MBW complex. However, gis and the R3 MYB gene mutant tcl1 (trichomeless 1) have opposite inflorescence trichome phenotypes, but their relationship in regulating trichome formation remained unknown. By generating and characterization of the gis tcl1 double mutant, we found that trichome formation in the gis tcl1double and the tcl1 single mutants were largely indistinguishable, but the trichome formation in the 35S:TCL1/gis transgenic plant was similar to that in the gis mutant. By using quantitative RT-PCR analysis, we showed that expression level of GIS was increased in the triple mutant tcl1 try cpc, but the expression level of TCL1 was not affected in the gis mutant. On the other hand, trichome morphology in both gis tcl1 and 35S:TCL1/gis plants was similar to that in the gis mutant. In summary, our results indicate that GIS may work downstream of TCL1 to regulate trichome formation, and GIS has a dominant role in controlling trichome morphology.

  20. Network analysis reveals the recognition mechanism for complex formation of mannose-binding lectins

    NASA Astrophysics Data System (ADS)

    Jian, Yiren; Zhao, Yunjie; Zeng, Chen

    The specific carbohydrate binding of lectin makes the protein a powerful molecular tool for various applications including cancer cell detection due to its glycoprotein profile on the cell surface. Most biologically active lectins are dimeric. To understand the structure-function relation of lectin complex, it is essential to elucidate the short- and long-range driving forces behind the dimer formation. Here we report our molecular dynamics simulations and associated dynamical network analysis on a particular lectin, i.e., the mannose-binding lectin from garlic. Our results, further supported by sequence coevolution analysis, shed light on how different parts of the complex communicate with each other. We propose a general framework for deciphering the recognition mechanism underlying protein-protein interactions that may have potential applications in signaling pathways.

  1. Risk factors for pancreatic stone formation in autoimmune pancreatitis over a long-term course.

    PubMed

    Maruyama, Masahiro; Arakura, Norikazu; Ozaki, Yayoi; Watanabe, Takayuki; Ito, Tetsuya; Yoneda, Suguru; Maruyama, Masafumi; Muraki, Takashi; Hamano, Hideaki; Matsumoto, Akihiro; Kawa, Shigeyuki

    2012-05-01

    Autoimmune pancreatitis (AIP) has the potential to progress to a chronic state that forms pancreatic stones. The aim of this study was to clarify the risk factors underlying pancreatic stone formation in AIP. Sixty-nine patients with AIP who had been followed for at least 3 years were enrolled for evaluation of clinical and laboratory factors as well as computed tomography and endoscopic retrograde cholangiopancreatography findings. During the course of this study, increased or de novo stone formation was seen in 28 patients, who were defined as the stone-forming group. No stones were observed in 32 patients, who were defined as the non-stone-forming group. Nine patients who had stones at diagnosis but showed no change during the course of this study were excluded from our cohort. Univariate analysis revealed no significant differences in clinical or laboratory factors associated with AIP-specific inflammation between the two groups. However, pancreatic head swelling (P = 0.006) and narrowing of both Wirsung's and Santorini's ducts in the pancreatic head region (P = 0.010) were significantly more frequent in the stone-forming group. Furthermore, multivariate analysis identified Wirsung and Santorini duct narrowing at diagnosis as a significant independent risk factor for pancreatic stone formation (OR 4.4, P = 0.019). A primary risk factor for pancreatic stone formation in AIP was narrowing of both Wirsung's and Santorini's ducts, which most presumably led to pancreatic juice stasis and stone development.

  2. Formation and antimicrobial activity of complexes of beta-cyclodextrin and some antimycotic imidazole derivatives.

    PubMed

    Van Doorne, H; Bosch, E H; Lerk, C F

    1988-04-22

    Complex formation between beta-cyclodextrin and six antimycotic imidazole derivatives has been studied. The solubility of all drugs was increased in the presence of beta-cyclodextrin. The smallest increase (approx. 5-fold) was observed for miconazol, and the largest increase (approx. 160-fold) was observed for bifonazol. Apparent 1:1-complex constants were measured and found to decrease in the order: bifonazol greater than ketoconazol greater than tioconazol greater than miconazol greater than itraconazol greater than clotrimazol. The complexes appeared to possess a low, if any, antimicrobial activity. Measurement of inhibition zone sizes, with four test organisms was used to study the release of the antimycotic drugs from topical preparations. The antimycotic drugs were more readily released from topical preparations containing beta-cyclodextrin than from the same vehicles without beta-cyclodextrin. The rationale of beta-cyclodextrin addition to antimycotic topical preparations is discussed.

  3. Reactions of a Chromium(III)-Superoxo Complex and Nitric Oxide That Lead to the Formation of Chromium(IV)-Oxo and Chromium(III)-Nitrito Complexes

    PubMed Central

    Yokoyama, Atsutoshi; Cho, Kyung-Bin

    2013-01-01

    The reaction of an end-on Cr(III)-superoxo complex bearing a 14-membered tetraazamacrocyclic TMC ligand, [CrIII(14-TMC)(O2)(Cl)]+, with nitric oxide (NO) resulted in the generation of a stable Cr(IV)-oxo species, [CrIV(14-TMC)(O)(Cl)]+, via the formation of a Cr(III)-peroxynitrite intermediate and homolytic O-O bond cleavage of the peroxynitrite ligand. Evidence for the latter comes from EPR spectroscopy, computational chemistry, and the observation of phenol nitration chemistry. The Cr(IV)-oxo complex does not react with nitrogen dioxide (NO2), but reacts with NO to afford a Cr(III)-nitrito complex, [CrIII(14-TMC)(NO2)(Cl)]+. The Cr(IV)-oxo and Cr(III)-nitrito complexes were also characterized spectroscopically and/or structurally. PMID:24066924

  4. N-type molecular electrical doping in organic semiconductors: formation and dissociation efficiencies of charge transfer complex

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Min; Yoo, Seung-Jun; Moon, Chang-Ki; Sim, Bomi; Lee, Jae-Hyun; Lim, Heeseon; Kim, Jeong Won; Kim, Jang-Joo

    2016-09-01

    Electrical doping is an important method in organic electronics to enhance device efficiency by controlling Fermi level, increasing conductivity, and reducing injection barrier from electrode. To understand the charge generation process of dopant in doped organic semiconductors, it is important to analyze the charge transfer complex (CTC) formation and dissociation into free charge carrier. In this paper, we correlate charge generation efficiency with the CTC formation and dissociation efficiency of n-dopant in organic semiconductors (OSs). The CTC formation efficiency of Rb2CO3 linearly decreases from 82.8% to 47.0% as the doping concentration increases from 2.5 mol% to 20 mol%. The CTC formation efficiency and its linear decrease with doping concentration are analytically correlated with the concentration-dependent size and number of dopant agglomerates by introducing the degree of reduced CTC formation. Lastly, the behavior of dissociation efficiency is discussed based on the picture of the statistical semiconductor theory and the frontier orbital hybridization model.

  5. Integration host factor is important for biofilm formation by Salmonella enterica Enteritidis.

    PubMed

    Leite, Bruna; Werle, Catierine Hirsch; Carmo, Camila Pinheiro do; Nóbrega, Diego Borin; Milanez, Guilherme Paier; Culler, Hebert Fabricio; Sircili, Marcelo Palma; Alvarez-Martinez, Cristina E; Brocchi, Marcelo

    2017-08-31

    Salmonella enterica Enteritidis forms biofilms and survives in agricultural environments, infecting poultry and eggs. Bacteria in biofilms are difficult to eradicate compared to planktonic cells, causing serious problems in industry and public health. In this study, we evaluated the role of ihfA and ihfB in biofilm formation by S. enterica Enteritidis by employing different microbiology techniques. Our data indicate that ihf mutant strains are impaired in biofilm formation, showing a reduction in matrix formation and a decrease in viability and metabolic activity. Phenotypic analysis also showed that deletion of ihf causes a deficiency in curli fimbriae expression, cellulose production and pellicle formation. These results show that integration host factor has an important regulatory role in biofilm formation by S. enterica Enteritidis. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Formation mechanism of a silane-PVA/PVAc complex film on a glass fiber surface.

    PubMed

    Repovsky, Daniel; Jane, Eduard; Palszegi, Tibor; Slobodnik, Marek; Velic, Dusan

    2013-10-21

    from -64 to -12 mV at pH's of 10.5 and 3, respectively. The zeta potentials for the PVA/PVAc microspheres on the glass fiber surface and within the silane film significantly decrease and range from -25 to -5 mV. The shapes of the pH-dependent zeta potentials are different in the cases of silane groups over a pH range from 7 to 4. A triple-layer model is used to fit the non-silanized glass surface and the silane film. The value of the surface-site density for Γ(Xglass) and Γ(Xsilane), in which X denotes the Al-O-Si group, differs by a factor of 10(-4), which suggests an effective coupling of the silane film. A soft-layer model is used to fit the silane-PVA/PVAc complex film, which is approximated as four layers. Such a simplification and compensation of the microsphere shape gives an approximation of the relevant widths of the layers as the follows: 1) the layer of the silane groups makes up 10% of the total length (27 nm), 2) the layer of the first PVA shell contributes 30% to the total length (81 nm), 3) the layer of the PVAc core contributes 30% to the total length (81 nm), and finally 4) the layer of the second PVA shell provides 30% of the total length (81 nm). The coverage simulation resulted in a value of 0.4, which corresponds with the assumption of low-order coverage, and is supported by the AFM scans. Correlating the results of the AFM scans, and the zeta potentials sheds some light on the formation mechanism of the silane-PVA/PVAc complex film. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Factors Mediating Environmental Biofilm Formation by Legionella pneumophila.

    PubMed

    Abu Khweek, Arwa; Amer, Amal O

    2018-01-01

    Legionella pneumophila ( L. pneumophila ) is an opportunistic waterborne pathogen and the causative agent for Legionnaires' disease, which is transmitted to humans via inhalation of contaminated water droplets. The bacterium is able to colonize a variety of man-made water systems such as cooling towers, spas, and dental lines and is widely distributed in multiple niches, including several species of protozoa In addition to survival in planktonic phase, L. pneumophila is able to survive and persist within multi-species biofilms that cover surfaces within water systems. Biofilm formation by L. pneumophila is advantageous for the pathogen as it leads to persistence, spread, resistance to treatments and an increase in virulence of this bacterium. Furthermore, Legionellosis outbreaks have been associated with the presence of L. pneumophila in biofilms, even after the extensive chemical and physical treatments. In the microbial consortium-containing L. pneumophila among other organisms, several factors either positively or negatively regulate the presence and persistence of L. pneumophila in this bacterial community. Biofilm-forming L. pneumophila is of a major importance to public health and have impact on the medical and industrial sectors. Indeed, prevention and removal protocols of L. pneumophila as well as diagnosis and hospitalization of patients infected with this bacteria cost governments billions of dollars. Therefore, understanding the biological and environmental factors that contribute to persistence and physiological adaptation in biofilms can be detrimental to eradicate and prevent the transmission of L. pneumophila . In this review, we focus on various factors that contribute to persistence of L. pneumophila within the biofilm consortium, the advantages that the bacteria gain from surviving in biofilms, genes and gene regulation during biofilm formation and finally challenges related to biofilm resistance to biocides and anti-Legionella treatments.

  8. Salmonella exploits the host endolysosomal tethering factor HOPS complex to promote its intravacuolar replication

    PubMed Central

    Sindhwani, Aastha; Kaur, Harmeet; Tuli, Amit

    2017-01-01

    Salmonella enterica serovar typhimurium extensively remodels the host late endocytic compartments to establish its vacuolar niche within the host cells conducive for its replication, also known as the Salmonella-containing vacuole (SCV). By maintaining a prolonged interaction with late endosomes and lysosomes of the host cells in the form of interconnected network of tubules (Salmonella-induced filaments or SIFs), Salmonella gains access to both membrane and fluid-phase cargo from these compartments. This is essential for maintaining SCV membrane integrity and for bacterial intravacuolar nutrition. Here, we have identified the multisubunit lysosomal tethering factor—HOPS (HOmotypic fusion and Protein Sorting) complex as a crucial host factor facilitating delivery of late endosomal and lysosomal content to SCVs, providing membrane for SIF formation, and nutrients for intravacuolar bacterial replication. Accordingly, depletion of HOPS subunits significantly reduced the bacterial load in non-phagocytic and phagocytic cells as well as in a mouse model of Salmonella infection. We found that Salmonella effector SifA in complex with its binding partner; SKIP, interacts with HOPS subunit Vps39 and mediates recruitment of this tethering factor to SCV compartments. The lysosomal small GTPase Arl8b that binds to, and promotes membrane localization of Vps41 (and other HOPS subunits) was also required for HOPS recruitment to SCVs and SIFs. Our findings suggest that Salmonella recruits the host late endosomal and lysosomal membrane fusion machinery to its vacuolar niche for access to host membrane and nutrients, ensuring its intracellular survival and replication. PMID:29084291

  9. Bi-Factor MIRT Observed-Score Equating for Mixed-Format Tests

    ERIC Educational Resources Information Center

    Lee, Guemin; Lee, Won-Chan

    2016-01-01

    The main purposes of this study were to develop bi-factor multidimensional item response theory (BF-MIRT) observed-score equating procedures for mixed-format tests and to investigate relative appropriateness of the proposed procedures. Using data from a large-scale testing program, three types of pseudo data sets were formulated: matched samples,…

  10. A Multi-wavelength Study of Star Formation Activity in the S235 Complex

    NASA Astrophysics Data System (ADS)

    Dewangan, L. K.; Ojha, D. K.; Luna, A.; Anandarao, B. G.; Ninan, J. P.; Mallick, K. K.; Mayya, Y. D.

    2016-03-01

    We have carried out an extensive multi-wavelength study to investigate the star formation process in the S235 complex. The S235 complex has a spherelike shell appearance at wavelengths longer than 2 μm and harbors an O9.5V type star approximately at its center. A near-infrared extinction map of the complex traces eight subregions (having AV > 8 mag), and five of them appear to be distributed in an almost regularly spaced manner along the spherelike shell surrounding the ionized emission. This picture is also supported by the integrated 12CO and 13CO intensity maps and by Bolocam 1.1 mm continuum emission. The position-velocity analysis of CO reveals an almost semi-ringlike structure, suggesting an expanding H II region. We find that the Bolocam clump masses increase as we move away from the location of the ionizing star. This correlation is seen only for those clumps that are distributed near the edges of the shell. Photometric analysis reveals 435 young stellar objects (YSOs), 59% of which are found in clusters. Six subregions (including five located near the edges of the shell) are very well correlated with the dust clumps, CO gas, and YSOs. The average values of Mach numbers derived using NH3 data for three (East 1, East 2, and Central E) out of these six subregions are 2.9, 2.3, and 2.9, indicating these subregions are supersonic. The molecular outflows are detected in these three subregions, further confirming the ongoing star formation activity. Together, all these results are interpreted as observational evidence of positive feedback of a massive star.

  11. Complement C1q formation of immune complexes with milk caseins and wheat glutens in schizophrenia

    PubMed Central

    Severance, Emily G.; Gressitt, Kristin; Halling, Meredith; Stallings, Cassie R.; Origoni, Andrea E.; Vaughan, Crystal; Khushalani, Sunil; Alaedini, Armin; Dupont, Didier; Dickerson, Faith B.; Yolken, Robert H.

    2012-01-01

    Immune system factors including complement pathway activation are increasingly linked to the etiology and pathophysiology of schizophrenia. Complement protein, C1q, binds to and helps to clear immune complexes composed of immunoglobulins coupled to antigens. The antigenic stimuli for C1q activation in schizophrenia are not known. Food sensitivities characterized by elevated IgG antibodies to bovine milk caseins and wheat glutens have been reported in individuals with schizophrenia. Here, we examined the extent to which these food products might comprise the antigen component of complement C1q immune complexes in individuals with recent onset schizophrenia (n=38), non-recent onset schizophrenia (n=61) and non-psychiatric controls (n=63). C1q seropositivity was significantly associated with both schizophrenia groups (recent onset, odds ratio (OR)=8.02, p≤0.008; non-recent onset, OR=3.15, p≤0.03) compared to controls (logistic regression models corrected for age, sex, race and smoking status). Casein- and/or gluten-IgG binding to C1q was significantly elevated in the non-recent onset group compared to controls (OR=4.36, p≤0.01). Significant amounts of C1q-casein/gluten-related immune complexes and C1q correlations with a marker for gastrointestinal inflammation in non-recent onset schizophrenia suggests a heightened rate of food antigens in the systemic circulation, perhaps via a disease-associated altered intestinal permeability. In individuals who are in the early stages of disease onset, C1q activation may reflect the formation of immune complexes with non-casein- or non-gluten-related antigens, the presence of C1q autoantibodies, and/or a dissociated state of immune complex components. In conclusion, complement activation may be a useful biomarker to diagnose schizophrenia early during the course of the disease. Future prospective studies should evaluate the impacts of casein- and gluten-free diets on C1q activation in schizophrenia. PMID:22801085

  12. Microscopic Mechanism and Kinetics of Ice Formation at Complex Interfaces: Zooming in on Kaolinite

    PubMed Central

    2016-01-01

    Most ice in nature forms because of impurities which boost the exceedingly low nucleation rate of pure supercooled water. However, the microscopic details of ice nucleation on these substances remain largely unknown. Here, we have unraveled the molecular mechanism and the kinetics of ice formation on kaolinite, a clay mineral playing a key role in climate science. We find that the formation of ice at strong supercooling in the presence of this clay is about 20 orders of magnitude faster than homogeneous freezing. The critical nucleus is substantially smaller than that found for homogeneous nucleation and, in contrast to the predictions of classical nucleation theory (CNT), it has a strong two-dimensional character. Nonetheless, we show that CNT describes correctly the formation of ice at this complex interface. Kaolinite also promotes the exclusive nucleation of hexagonal ice, as opposed to homogeneous freezing where a mixture of cubic and hexagonal polytypes is observed. PMID:27269363

  13. Spectroscopic and thermodynamic study of charge transfer complex formation between cloxacillin sodium and riboflavin in aqueous ethanol media of varying composition

    NASA Astrophysics Data System (ADS)

    Roy, Dalim Kumar; Saha, Avijit; Mukherjee, Asok K.

    2006-03-01

    Cloxacillin sodium has been shown to form a charge transfer complex of 2:1 stoichiometry with riboflavin (Vitamin B 2) in aqueous ethanol medium. The enthalpy and entropy of formation of this complex have been determined by estimating the formation constant spectrophotometrically at five different temperatures in pure water medium. Pronounced effect of dielectric constant of the medium on the magnitude of K has been observed by determining K in aqueous ethanol mixtures of varying composition. This has been rationalized in terms of ionic dissociation of the cloxacillin sodium (D -Na +), hydrolysis of the anion D - and complexation of the free acid, DH with riboflavin.

  14. Reactions of guanine with methyl chloride and methyl bromide: O6-methylation versus charge transfer complex formation

    NASA Astrophysics Data System (ADS)

    Shukla, P. K.; Mishra, P. C.; Suhai, S.

    Density functional theory (DFT) at the B3LYP/6-31+G* and B3LYP/AUG-cc-pVDZ levels was employed to study O6-methylation of guanine due to its reactions with methyl chloride and methyl bromide and to obtain explanation as to why the methyl halides cause genotoxicity and possess mutagenic and carcinogenic properties. Geometries of the various isolated species involved in the reactions, reactant complexes (RCs), and product complexes (PCs) were optimized in gas phase. Transition states connecting the reactant complexes with the product complexes were also optimized in gas phase at the same levels of theory. The reactant complexes, product complexes, and transition states were solvated in aqueous media using the polarizable continuum model (PCM) of the self-consistent reaction field theory. Zero-point energy (ZPE) correction to total energy and the corresponding thermal energy correction to enthalpy were made in each case. The reactant complexes of the keto form of guanine with methyl chloride and methyl bromide in water are appreciably more stable than the corresponding complexes involving the enol form of guanine. The nature of binding in the product complexes was found to be of the charge transfer type (O6mG+ · X-, X dbond Cl, Br). Binding of HCl, HBr, and H2O molecules to the PCs obtained with the keto form of guanine did not alter the positions of the halide anions in the PCs, and the charge transfer character of the PCs was also not modified due to this binding. Further, the complexes obtained due to the binding of HCl, HBr, and H2O molecules to the PCs had greater stability than the isolated PCs. The reaction barriers involved in the formation of PCs were found to be quite high (?50 kcal/mol). Mechanisms of genotoxicity, mutagenesis and carcinogenesis caused by the methyl halides appear to involve charge transfer-type complex formation. Thus the mechanisms of these processes involving the methyl halides appear to be quite different from those that involve the

  15. Nephrin Regulates Lamellipodia Formation by Assembling a Protein Complex That Includes Ship2, Filamin and Lamellipodin

    PubMed Central

    Venkatareddy, Madhusudan; Cook, Leslie; Abuarquob, Kamal; Verma, Rakesh; Garg, Puneet

    2011-01-01

    Actin dynamics has emerged at the forefront of podocyte biology. Slit diaphragm junctional adhesion protein Nephrin is necessary for development of the podocyte morphology and transduces phosphorylation-dependent signals that regulate cytoskeletal dynamics. The present study extends our understanding of Nephrin function by showing in cultured podocytes that Nephrin activation induced actin dynamics is necessary for lamellipodia formation. Upon activation Nephrin recruits and regulates a protein complex that includes Ship2 (SH2 domain containing 5′ inositol phosphatase), Filamin and Lamellipodin, proteins important in regulation of actin and focal adhesion dynamics, as well as lamellipodia formation. Using the previously described CD16-Nephrin clustering system, Nephrin ligation or activation resulted in phosphorylation of the actin crosslinking protein Filamin in a p21 activated kinase dependent manner. Nephrin activation in cell culture results in formation of lamellipodia, a process that requires specialized actin dynamics at the leading edge of the cell along with focal adhesion turnover. In the CD16-Nephrin clustering model, Nephrin ligation resulted in abnormal morphology of actin tails in human podocytes when Ship2, Filamin or Lamellipodin were individually knocked down. We also observed decreased lamellipodia formation and cell migration in these knock down cells. These data provide evidence that Nephrin not only initiates actin polymerization but also assembles a protein complex that is necessary to regulate the architecture of the generated actin filament network and focal adhesion dynamics. PMID:22194892

  16. Antimicrobial resistance, biofilm formation and virulence reveal Actinobacillus pleuropneumoniae strains' pathogenicity complexity.

    PubMed

    Pereira, Monalessa Fábia; Rossi, Ciro César; Seide, Larissa Eler; Martins Filho, Sebastião; Dolinski, Cláudia de Melo; Bazzolli, Denise Mara Soares

    2018-05-07

    Porcine pleuropneumonia is an important cause of lowered productivity and economic loss in the pig industry worldwide, associated primarily with Actinobacillus pleuropneumoniae infection. Its colonization and persistence within the upper respiratory tract of affected pigs depends upon interactions between a number of genetically controlled virulence factors, such as pore-forming repeats-in-toxin exoproteins, biofilm formation, and antimicrobial resistance. This study investigated correlations between biofilm-forming capacity, antimicrobial resistance, and virulence of A. pleuropneumoniae obtained from clinical outbreaks of disease, using a Galleria mellonella alternative infection model. Results suggest that virulence is diverse amongst the 21 strains of A. pleuropneumoniae examined and biofilm formation correlated with genetic control of antimicrobial resistance. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Fluorescent Filter-Trap Assay for Amyloid Fibril Formation Kinetics in Complex Solutions

    PubMed Central

    2015-01-01

    Amyloid fibrils are the most distinct components of the plaques associated with various neurodegenerative diseases. Kinetic studies of amyloid fibril formation shed light on the microscopic mechanisms that underlie this process as well as the contributions of internal and external factors to the interplay between different mechanistic steps. Thioflavin T is a widely used noncovalent fluorescent probe for monitoring amyloid fibril formation; however, it may suffer from limitations due to the unspecific interactions between the dye and the additives. Here, we present the results of a filter-trap assay combined with the detection of fluorescently labeled amyloid β (Aβ) peptide. The filter-trap assay separates formed aggregates based on size, and the fluorescent label attached to Aβ allows for their detection. The times of half completion of the process (t1/2) obtained by the filter-trap assay are comparable to values from the ThT assay. High concentrations of human serum albumin (HSA) and carboxyl-modified polystyrene nanoparticles lead to an elevated ThT signal, masking a possible fibril formation event. The filter-trap assay allows fibril formation to be studied in the presence of those substances and shows that Aβ fibril formation is kinetically inhibited by HSA and that the amount of fibrils formed are reduced. In contrast, nanoparticles exhibit a dual-behavior governed by their concentration. PMID:25946560

  18. Binding regularities in complexes of transcription factors with operator DNA: homeodomain family.

    PubMed

    Chirgadze, Yu N; Zheltukhin, E I; Polozov, R V; Sivozhelezov, V S; Ivanov, V V

    2009-06-01

    In order to disclose general regularities of binding in homeodomain-DNA complexes we considered five of them and extended the observed regularities over the entire homeodomain family. The five complexes have been selected by similarity of protein structures and patterns of contacting residues. Their long range interactions and interfaces were compared. The long-range stage of the recognition process was characterized by electrostatic potentials about 5 Angstrom away from molecular surfaces of protein or DNA. For proteins, clear positive potential is displayed only at the side contacting the DNA. The double-chained DNA molecule displays a rather strong negative potential, especially in their grooves. Thus, a functional role of electrostatics is a guiding of the protein into the DNA major groove, so the protein and DNA could form a loose non-specific complex. At the close-range stage, neutralization of the phosphate charges by positively charged residues is necessary for decreasing the strong electrostatic potential of DNA, allowing nucleotide bases to participate in the formation of protein-DNA atomic contacts in the interface. The recognizing alpha-helix of protein was shown to form both invariant and variable groups of contacts with DNA by means of certain specific side groups. The invariant contacts included highly specific protein-DNA hydrogen bonds between asparagine and adenine, nonpolar contacts of hydrophobic amino acids serving as a stereochemical barrier for fixing the protein factor on DNA, and an interface cluster of water molecules providing local conformational mobility necessary for the dissociation process. There is a unique water molecule within the interface that is conservative and located at the interface center. Invariant contacts of the proteins are mostly formed with the TAAT motif of the promoter DNA forward strand. While the invariant contacts specify the family of homeodomains, the variable contacts that are formed with the reverse strand

  19. Dependence of the enthalpies of formation of glycylglycinate complexes of nickel(II) on the composition of a mixed water-dimethylsulfoxide solvent

    NASA Astrophysics Data System (ADS)

    Naumov, V. V.; Kovaleva, Yu. A.; Isaeva, V. A.; Usacheva, T. R.; Sharnin, V. A.

    2014-06-01

    The heat effects of the complexation reactions of nickel(II) with a glycylglycinate ion in a water-dimethylsulfoxide solvent in a range of compositions of 0.00-0.60 molar parts of dimethylsulfoxide (DMSO) (an ionic strength of 0.1 was maintained using sodium perchlorate) were determined by means of calorimetry at 298.15 K. It is established that the exothermicity of complexation reactions rises by the first two steps and falls upon the addition of a third glycylglycinate anion with an increase in the concentration of DMSO. It is shown that the formation of mono- and bis-glycylglycinate complexes of nickel(II) in a water-DMSO solvent is determined mostly by the enthalpic contribution. It is concluded that the formation of tris-ligand complexes is more associated with the entropic contribution.

  20. Thermodynamic Investigation and Mixed Ligand Complex Formation of 1,4-Bis-(3-aminopropyl)-piperazine and Biorelevant Ligands.

    PubMed

    El-Sherif, Ahmed A; Shehata, Mohamed R; Shoukry, Mohamed M; Barakat, Mohammad H

    2012-01-01

    Thermodynamic parameters for protonation of 1,4-bis(3-aminopropyl)-piperazine (BAPP) and its metal complexation with some divalent metal ions were determined in aqueous solution at constant ionic strength (0.1 M NaNO(3)) using a potentiometric technique. The order of -ΔG(0) and -ΔH(0) was found to obey Co(2+) < Ni(2+) < Cu(2+) > Zn(2+), in accordance with the Irving-Williams order. The formation equilibria of zinc (II) complexes and the ternary complexes Zn(BAPP)L, where L = amino acid, amides, or DNA constituents), have been investigated. Ternary complexes are formed by a simultaneous mechanism. The concentration distribution of the complexes in solution was evaluated as a function of pH. Stoichiometry and stability constants for the complexes formed are reported and discussed. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameter Δlog K.

  1. Thermodynamic Investigation and Mixed Ligand Complex Formation of 1,4-Bis-(3-aminopropyl)-piperazine and Biorelevant Ligands

    PubMed Central

    El-Sherif, Ahmed A.; Shehata, Mohamed R.; Shoukry, Mohamed M.; Barakat, Mohammad H.

    2012-01-01

    Thermodynamic parameters for protonation of 1,4-bis(3-aminopropyl)-piperazine (BAPP) and its metal complexation with some divalent metal ions were determined in aqueous solution at constant ionic strength (0.1 M NaNO3) using a potentiometric technique. The order of –ΔG0 and –ΔH0 was found to obey Co2+ < Ni2+ < Cu2+ > Zn2+, in accordance with the Irving-Williams order. The formation equilibria of zinc (II) complexes and the ternary complexes Zn(BAPP)L, where L = amino acid, amides, or DNA constituents), have been investigated. Ternary complexes are formed by a simultaneous mechanism. The concentration distribution of the complexes in solution was evaluated as a function of pH. Stoichiometry and stability constants for the complexes formed are reported and discussed. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameter Δlog K. PMID:23226992

  2. A Review and Conceptual Model of Factors Correlated with Postmortem Root Band Formation.

    PubMed

    Donfack, Joseph; Castillo, Hilda S

    2018-03-12

    It is generally accepted within the forensic trace evidence community that a postmortem root band (PMRB) can appear in the root of hairs attached to remains during decomposition. Presently, the specific sequences of events and/or exact molecular signals that lead to the formation of a PMRB are not well understood. The published literature addressing the abiotic and biotic factors that correlate with the formation of PMRBs is reviewed and a conceptual model for the formation of PMRBs is proposed. © 2018 American Academy of Forensic Sciences.

  3. Preliminary Study for a Tetrahedron Formation: Quality Factors and Visualization

    NASA Technical Reports Server (NTRS)

    Guzman, Jose J.; Schiff, Conrad; Bauer, Frank (Technical Monitor)

    2002-01-01

    Spacecraft flying in tetrahedron formations are excellent for electromagnetic and plasma studies. The quality of the science recorded is strongly affected by the tetrahedron evolution. This paper is a preliminary study on the computation of quality factors and visualization for a formation of four or five satellites. Four of the satellites are arranged geometrically in a tetrahedron shape. If a fifth satellite is present, it is arbitrarily initialized at the geometric center of the tetrahedron. The fifth satellite could act as a collector or as a spare spacecraft. Tetrahedron natural coordinates are employed for the initialization. The natural orbit evolution is visualized in geocentric equatorial inertial and in geocentric solar magnetospheric coordinates.

  4. Formation of lactoferrin/sodium caseinate complexes and their adsorption behaviour at the air/water interface.

    PubMed

    Li, Quanyang; Zhao, Zhengtao

    2017-10-01

    This research investigated the complexation behaviour between lactoferrin (Lf) and sodium caseinate (NaCas) before and after heat treatment. The results showed that heating facilitated their interaction and different complexes were formed at different Lf/NaCas ratios. The presence of low concentrations of NaCas resulted in the rapid precipitation of Lf, while no precipitation was observed at the NaCas concentrations higher than Lf/NaCas ratio of 2:1. The formed complexes at the ratio of 2:1 have an average diameter of 194±9.0nm and they exhibited a great capacity in lowering the air/water interfacial tension. Further increase of NaCas concentration to ratios of 1:1 and 1:2 resulted in the formation of smaller complexes with average diameters of 60±2.5nm. The complexes formed at these two ratios showed similar adsorption behaviour at the air/water interface and they exhibited lower capacity in decreasing the interfacial tension than the ratio of 2:1. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. New 3D coordination polymers constructed from pillared metal-formate Kagomé layers exhibiting spin canting only in the nickel(II) complex.

    PubMed

    Li, Zuo-Xi; Zhao, Jiong-Peng; Sañudo, E C; Ma, Hong; Pan, Zhong-Da; Zeng, Yong-Fei; Bu, Xian-He

    2009-12-21

    Sparked by the strategy of pillared-layer MOFs, three formate coordination polymers, {[Ni(2)(HCO(2))(3)(L)(2)](NO(3)).2H(2)O}(infinity) (1), {[Co(2)(HCO(2))(3)(L)(2)](HCO(2)).2H(2)O}(infinity) (2), and {[Cu(2)(HCO(2))(3)(L)(2)](HCO(2)).2H(2)O}(infinity) (3), have been synthesized by employing the rodlike ligand 4,4'-bis(imidazol-1-yl)biphenyl (L) as the pillar. Structural analysis indicates that the title complexes 1-3 are isostructural compounds, which possess metal-formate 2D layers perpendicularly pillared by the ligand L to afford a 3D open framework. This is an interesting example of a Kagome lattice based on the formate mediator. Moreover, the formate anion of this 2D Kagome layer exhibits various bridging modes: anti-anti, syn-anti, and 3.21 modes. Their magnetic measurements reveals that only complex 1 presents the spin canting phenomenon, while its isostructural Co(II) and Cu(II) complexes are simply paramagnets with antiferromagnetic coupling.

  6. Plant polyadenylation factors: conservation and variety in the polyadenylation complex in plants.

    PubMed

    Hunt, Arthur G; Xing, Denghui; Li, Qingshun Q

    2012-11-20

    Polyadenylation, an essential step in eukaryotic gene expression, requires both cis-elements and a plethora of trans-acting polyadenylation factors. The polyadenylation factors are largely conserved across mammals and fungi. The conservation seems also extended to plants based on the analyses of Arabidopsis polyadenylation factors. To extend this observation, we systemically identified the orthologs of yeast and human polyadenylation factors from 10 plant species chosen based on both the availability of their genome sequences and their positions in the evolutionary tree, which render them representatives of different plant lineages. The evolutionary trajectories revealed several interesting features of plant polyadenylation factors. First, the number of genes encoding plant polyadenylation factors was clearly increased from "lower" to "higher" plants. Second, the gene expansion in higher plants was biased to some polyadenylation factors, particularly those involved in RNA binding. Finally, while there are clear commonalities, the differences in the polyadenylation apparatus were obvious across different species, suggesting an ongoing process of evolutionary change. These features lead to a model in which the plant polyadenylation complex consists of a conserved core, which is rather rigid in terms of evolutionary conservation, and a panoply of peripheral subunits, which are less conserved and associated with the core in various combinations, forming a collection of somewhat distinct complex assemblies. The multiple forms of plant polyadenylation complex, together with the diversified polyA signals may explain the intensive alternative polyadenylation (APA) and its regulatory role in biological functions of higher plants.

  7. XAFS Debye-Waller Factors Temperature-Dependent Expressions for Fe+2-Porphyrin Complexes

    NASA Astrophysics Data System (ADS)

    Dimakis, Nicholas; Bunker, Grant

    2007-02-01

    We present an efficient and accurate method for directly calculating single and multiple scattering X-ray absorption fine structure (XAFS) thermal Debye-Waller factors for Fe+2 -porphiryn complexes. The number of multiple scattering Debye-Waller factors on metal porphyrin centers exceeds the number of available parameters that XAFS experimental data can support during fitting with simulated spectra. Using the Density Functional Theory (DFT) under the hybrid functional of X3LYP, phonon normal mode spectrum properties are used to express the mean square variation of the half-scattering path length for a Fe+2 -porphiryn complex as a function of temperature for the most important single and multiple scattering paths of the complex thus virtually eliminating them from the fitting procedure. Modeled calculations are compared with corresponding values obtained from DFT-built and optimized Fe+2 -porphyrin bis-histidine structure as well as from experimental XAFS spectra previously reported. An excellent agreement between calculated and reference Debye-Waller factors for Fe+2-porphyrins is obtained.

  8. The Cobalt cyclo‐P4 Sandwich Complex and Its Role in the Formation of Polyphosphorus Compounds

    PubMed Central

    Dielmann, Fabian; Timoshkin, Alexey; Piesch, Martin; Balázs, Gábor

    2017-01-01

    Abstract A synthetic approach to the sandwich complex [Cp′′′Co(η4‐P4)] (2) containing a cyclo‐P4 ligand as an end‐deck was developed. Complex 2 is the missing homologue in the series of first‐row cyclo‐Pn sandwich complexes, and shows a unique tendency to dimerize in solution to form two isomeric P8 complexes [(Cp′′′Co)2(μ,η4:η2:η1‐P8)] (3 and 4). Reactivity studies indicate that 2 and 3 react with further [Cp′′′Co] fragments to give [(Cp′′′Co)2(μ,η2:η2‐P2)2] (5) and [(Cp′′′Co)3P8] (6), respectively. Furthermore, complexes 2, 3, and 4 thermally decompose forming 5, 6, and the P12 complex [(Cp′′′Co)3P12] (7). DFT calculations on the P4 activation process suggest a η3‐P4 Co complex as the key intermediate in the synthesis of 2 as well as in the formation of larger polyphosphorus complexes via a unique oligomerization pathway. PMID:28078794

  9. Coordination properties of tridentate (N,O,O) heterocyclic alcohol (PDC) with Cu(II). Mixed ligand complex formation reactions of Cu(II) with PDC and some bio-relevant ligands.

    PubMed

    El-Sherif, Ahmed A; Shoukry, Mohamed M

    2007-03-01

    The formation equilibria of copper(II) complexes and the ternary complexes Cu(PDC)L (PDC=2,6-bis-(hydroxymethyl)-pyridine, HL=amino acid, amides or DNA constituents) have been investigated. Ternary complexes are formed by a simultaneous mechanism. The results showed the formation of Cu(PDC)L, Cu(PDC, H(-1))(L) and Cu(PDC, H(-2))(L) complexes. The concentration distribution of the complexes in solution is evaluated as a function of pH. The effect of dioxane as a solvent on the protonation constant of PDC and the formation constants of Cu(II) complexes are discussed. The thermodynamic parameters DeltaH degrees and DeltaS degrees calculated from the temperature dependence of the equilibrium constants are investigated.

  10. Formative Constructs Implemented via Common Factors

    ERIC Educational Resources Information Center

    Treiblmaier, Horst; Bentler, Peter M.; Mair, Patrick

    2011-01-01

    Recently there has been a renewed interest in formative measurement and its role in properly specified models. Formative measurement models are difficult to identify, and hence to estimate and test. Existing solutions to the identification problem are shown to not adequately represent the formative constructs of interest. We propose a new two-step…

  11. Percutaneous radiofrequency ablation of hepatic tumours: factors affecting technical failure of artificial ascites formation using an angiosheath.

    PubMed

    Kang, T W; Lee, M W; Hye, M J; Song, K D; Lim, S; Rhim, H; Lim, H K; Cha, D I

    2014-12-01

    To evaluate the technical feasibility of artificial ascites formation using an angiosheath before percutaneous radiofrequency ablation (RFA) for hepatic tumours and to determine predictive factors affecting the technical failure of artificial ascites formation. This retrospective study was approved by the institutional review board. One hundred and thirteen patients underwent percutaneous RFA of hepatic tumours after trying to make artificial ascites using an angiosheath to avoid collateral thermal damage. The technical success rate of making artificial ascites using an angiosheath and conversion rate to other techniques after initial failure of making artificial ascites were evaluated. The technical success rate for RFA was assessed. In addition, potential factors associated with technical failure including previous history of transcatheter arterial chemoembolization (TACE) or RFA, type of abdominal surgery, and adjacent perihepatic structures were reviewed. Predictive factors for the technical failure of artificial ascites formation were analysed using multivariate analysis. The technical success rates of artificial ascites formation by angiosheath and that of RFA were 84.1% (95/113) and 97.3% (110/113), respectively. The conversion rate to other techniques after the failure of artificial ascites formation using an angiosheath was 15.9% (18/113). Previous hepatic resection was the sole independent predictive factor affecting the technical failure of artificial ascites formation (p<0.001, odds ratio = 29.03, 95% confidence interval: 4.56-184.69). Making artificial ascites for RFA of hepatic tumours using an angiosheath was technically feasible in most cases. However, history of hepatic resection was a significant predictive factor affecting the technical failure of artificial ascites formation. Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  12. Thermodynamic Characteristics of Reactions of the Formation of Complexes between Triglycine and Ni2+ Ions in Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Gorboletova, G. G.; Metlin, A. A.; Bychkova, S. A.

    2018-05-01

    Thermal effects of reactions of the formation of complexes between Ni(II) and triglycine are determined via direct calorimetry in aqueous solutions at 298.15 K and ionic strengths of 0.2, 0.5, and 1.0 (KNO3). Standard thermodynamic characteristics (Δr H°, Δr G°, Δr S°) of complexing processes in the investigated systems are calculated. The structures of triglycinate complexes NiL+, NiH-1L, NiL2, NiH-2L2- 2, NiL- 3, and NiH-3L4- 3 are introduced to compare the obtained values and data on the thermodynamics of triglycinate complexes of Ni(II).

  13. Entropy-driven complex formation of malvidin-3- O-glucoside with common polyphenols in ethanol-water binary solutions

    NASA Astrophysics Data System (ADS)

    Kunsági-Máté, Sándor; Ortmann, Erika; Kollár, László; Nikfardjam, Martin Pour

    2008-09-01

    The complex formation of malvidin-3- O-glucoside with several polyphenols, the so-called "copigmentation" phenomenon, was studied in aqueous solutions. To simulate the copigmentation process during fermentation, the stability of the formed complexes was examined in dependence of the ethanol content of the aqueous solution. Results indicate that stronger and larger complexes are formed, when the ethanol content exceeds a critical margin of 8 vol.% However, the size of complexes of malvidin/procyanidin and malvidin/epicatechin is drastically reduced above this critical concentration. Fluorescence lifetime and solvent relaxation measurements give insight into the particular processes at molecular level and will help us comprehend the first important steps during winemaking in order to recommend an optimized winemaking technology to ensure extraordinary colour stability in red wines.

  14. Effect of fat type in baked bread on amylose-lipid complex formation and glycaemic response.

    PubMed

    Lau, Evelyn; Zhou, Weibiao; Henry, Christiani Jeyakumar

    2016-06-01

    The formation of amylose-lipid complexes (ALC) had been associated with reduced starch digestibility. A few studies have directly characterised the extent of ALC formation with glycaemic response. The objectives of this study were to investigate the effect of using fats with varying degree of saturation and chain length on ALC formation as well as glycaemic and insulinaemic responses after consumption of bread. Healthy men consumed five test breads in a random order: control bread without any added fats (CTR) and breads baked with butter (BTR), coconut oil (COC), grapeseed oil (GRP) or olive oil (OLV). There was a significant difference in glycaemic response between the different test breads (P=0·002), primarily due to COC having a lower response than CTR (P=0·016), but no significant differences between fat types were observed. Insulinaemic response was not altered by the addition of fats/oils. Although BTR was more insulinotropic than GRP (P<0·05), postprandial β-cell function did not differ significantly. The complexing index (CI), a measure of ALC formation, was significantly higher for COC and OLV compared with BTR and GRP (P<0·05). CI was significantly negatively correlated with incremental AUC (IAUC) of change in blood glucose concentrations over time (IAUCglucose) (r -0·365, P=0·001). Linear regression analysis showed that CI explained 13·3 % of the variance and was a significant predictor of IAUCglucose (β=-1·265, P=0·001), but IAUCinsulin did not predict IAUCglucose. Our study indicated that a simple way to modulate glycaemic response in bread could lie in the choice of fats/oils, with coconut oil showing the greatest attenuation of glycaemic response.

  15. In vitro formation of the Merkel cell-neurite complex in embryonic mouse whiskers using organotypic co-cultures.

    PubMed

    Ishida, Kentaro; Saito, Tetsuichiro; Mitsui, Toshiyuki

    2018-06-01

    A Merkel cell-neurite complex is a touch receptor composed of specialized epithelial cells named Merkel cells and peripheral sensory nerves in the skin. Merkel cells are found in touch-sensitive skin components including whisker follicles. The nerve fibers that innervate Merkel cells of a whisker follicle extend from the maxillary branch of the trigeminal ganglion. Whiskers as a sensory organ attribute to the complicated architecture of the Merkel cell-neurite complex, and therefore it is intriguing how the structure is formed. However, observing the dynamic process of the formation of a Merkel cell-neurite complex in whiskers during embryonic development is still difficult. In this study, we tried to develop an organotypic co-culture method of a whisker pad and a trigeminal ganglion explant to form the Merkel cell-neurite complex in vitro. We initially developed two distinct culture methods of a single whisker row and a trigeminal ganglion explant, and then combined them. By dissecting and cultivating a single row from a whisker pad, the morphogenesis of whisker follicles could be observed under a microscope. After the co-cultivation of the whisker row with a trigeminal ganglion explant, a Merkel cell-neurite complex composed of Merkel cells, which were positive for both cytokeratin 8 and SOX2, Neurofilament-H-positive trigeminal nerve fibers and Schwann cells expressing Nestin, SOX2 and SOX10 was observed via immunohistochemical analyses. These results suggest that the process for the formation of a Merkel cell-neurite complex can be observed under a microscope using our organotypic co-culture method. © 2018 Japanese Society of Developmental Biologists.

  16. Nitrosothiol Formation and Protection against Fenton Chemistry by Nitric Oxide-induced Dinitrosyliron Complex Formation from Anoxia-initiated Cellular Chelatable Iron Increase*

    PubMed Central

    Li, Qian; Li, Chuanyu; Mahtani, Harry K.; Du, Jian; Patel, Aashka R.; Lancaster, Jack R.

    2014-01-01

    Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings associated with •NO. However, the iron source of cellular DNIC is unknown. Previous studies on this question using prolonged •NO exposure could be misleading due to the movement of intracellular iron among different sources. We here report that brief •NO exposure results in only barely detectable DNIC, but levels increase dramatically after 1–2 h of anoxia. This increase is similar quantitatively and temporally with increases in the chelatable iron, and brief •NO treatment prevents detection of this anoxia-induced increased chelatable iron by deferoxamine. DNIC formation is so rapid that it is limited by the availability of •NO and chelatable iron. We utilize this ability to selectively manipulate cellular chelatable iron levels and provide evidence for two cellular functions of endogenous DNIC formation, protection against anoxia-induced reactive oxygen chemistry from the Fenton reaction and formation by transnitrosation of protein nitrosothiols (RSNO). The levels of RSNO under these high chelatable iron levels are comparable with DNIC levels and suggest that under these conditions, both DNIC and RSNO are the most abundant cellular adducts of •NO. PMID:24891512

  17. Preparation and evaluation of periodontal films based on polyelectrolyte complex formation.

    PubMed

    Kassem, Abeer Ahmed; Ismail, Fatma Ahmed; Naggar, Viviane Fahim; Aboulmagd, Elsayed

    2015-05-01

    Local intra-pocket drug delivery devices can provide an effective concentration of the antimicrobial agent at the site of action with avoidance of undesirable side effects. This study explored the application of chitosan-alginate and chitosan-pectin polyelectrolyte complex (PEC) films as drug release regulators for tetracycline HCl (Tc) to treat periodontal pockets. Periodontal films with 1:1 Tc:PEC ratio were prepared using 1:1 chitosan (Ch) to sodium alginate (A) or 1:3 Ch to pectin (P). The scanning electron microscope showed acceptable film appearance and differential scanning calorimetry analysis confirmed complex formation. The in vitro release studies for both films showed a burst drug release, followed by prolonged release for 70 h. A prolonged antibacterial activity of both films against Staphylococcus aureus ATCC 6538 was observed over a period of 21 days. Aging studies indicated that the five months storage period in freezer did not significantly influence the drug release profile or the antibacterial activity of both films. Clinical evaluation showed a significant reduction in pocket depth (p < 0.0001) to their normal values (≤3 mm). PEC films could be exploited as a prolonged drug release devices for treatment of periodontal pockets.

  18. Formative Evaluation of Care Nexus: a Tool for the Visualization and Management of Care Teams of Complex Pediatric Patients

    PubMed Central

    Ranade-Kharkar, Pallavi; Norlin, Chuck; Del Fiol, Guilherme

    2017-01-01

    Complex and chronic conditions in pediatric patients with special needs often result in large and diverse patient care teams. Having a comprehensive view of the care teams is crucial to achieving effective and efficient care coordination for these vulnerable patients. In this study, we iteratively design and develop two alternative user interfaces (graphical and tabular) of a prototype of a tool for visualizing and managing care teams and conduct a formative assessment of the usability, usefulness, and efficiency of the tool. The median time to task completion for the 21 study participants was less than 7 seconds for 19 out of the 22 usability tasks. While both the prototype formats were well-liked in terms of usability and usefulness, the tabular format was rated higher for usefulness (p=0.02). Inclusion of CareNexus-like tools in electronic and personal health records has the potential to facilitate care coordination in complex pediatric patients. PMID:29854215

  19. Revised nomenclature and stratigraphic relationships of the Fredericksburg Complex and Quantico Formation of the Virginia Piedmont

    USGS Publications Warehouse

    Pavlides, Louis

    1980-01-01

    The Fredericksburg Complex, in part a migmatitic terrane in northeast Virginia, is subdivided on the basis of lithology, as well as aeromagnetic and aeroradiometric data, into two metamorphic suites. These suites are separated by the northeast-trending Spotsylvania lineament, a rectilinear geophysical feature that is probably the trace of an old fault zone. East of the lineament, the Po River Metamorphic Suite, of Proterozoic Z and (or) early Paleozoic age, consists dominantly of biotite gneiss, generally augen gneiss, and lesser amounts of hornblende gneiss and mica schist. West of the Spotsylvania lineament is the Ta River Metamorphic Suite, composed mostly of amphibolite and amphibole gneiss. However, to the southwest, along its strike belt, the Ta River contains abundant biotite gneiss and mica schist. Both the Ta River and Po River contain abundant foliated granitoid and pegmatoid bodies as concordant tabular masses and as crosscutting dikes; these rocks are considered part of the Ta River and Po River Metamorphic Suites. The amphibolitic Holly Corner Gneiss is interpreted to be a western allochthonous equivalent of the Ta River. Both the Ta River and Holly Corner are considered to be coeval, eastern, distal facies of the Lower Cambrian(?) Chopawamsic Formation. The Paleozoic Falls Run Granite Gneiss intrudes the Ta River Metamorphic Suite and the Holly Corner Gneiss; locally the Falls Run is interpreted to have been transported westward with the Holly Corner after intrusion. The Quantico Formation, in the core of the Quantico-Columbia synclinorium, rests with angular unconformity along its northwest and southeast limbs, respectively, on the Chopawamsic Formation and the Ta River Metamorphic Suite. The Quantico Formation is assigned the same Late Ordovician age and similar stratigraphic position as the Arvonia Slate of the Arvonia syncline. The youngest rocks of the area are the granitoid and pegmatoid bodies of the Falmouth Intrusive Suite. They consist of

  20. The Ethylene Responsive Factor Required for Nodulation 1 (ERN1) Transcription Factor Is Required for Infection-Thread Formation in Lotus japonicus.

    PubMed

    Kawaharada, Yasuyuki; James, Euan K; Kelly, Simon; Sandal, Niels; Stougaard, Jens

    2017-03-01

    Several hundred genes are transcriptionally regulated during infection-thread formation and development of nitrogen-fixing root nodules. We have characterized a set of Lotus japonicus mutants impaired in root-nodule formation and found that the causative gene, Ern1, encodes a protein with a characteristic APETALA2/Ethylene Responsive Factor (AP2/ERF) transcription-factor domain. Phenotypic characterization of four ern1 alleles shows that infection pockets are formed but root-hair infection threads are absent. Formation of root-nodule primordia is delayed and no normal transcellular infection threads are found in the infected nodules. Corroborating the role of ERN1 (ERF Required for Nodulation1) in nodule organogenesis, spontaneous nodulation induced by an autoactive CCaMK and cytokinin-induced nodule primordia were not observed in ern1 mutants. Expression of Ern1 is induced in the susceptible zone by Nod factor treatment or rhizobial inoculation. At the cellular level, the pErn1:GUS reporter is highly expressed in root epidermal cells of the susceptible zone and in the cortical cells that form nodule primordia. The genetic regulation of this cellular expression pattern was further investigated in symbiotic mutants. Nod factor induction of Ern1 in epidermal cells was found to depend on Nfr1, Cyclops, and Nsp2 but was independent of Nin and Nf-ya1. These results suggest that ERN1 functions as a transcriptional regulator involved in the formation of infection threads and development of nodule primordia and may coordinate these two processes.

  1. Dye Aggregation and Complex Formation Effects in 7-(Diethylamino)-coumarin-3-carboxylic Acid

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Xiaogang; Cole, Jacqueline M.; Chow, Philip C. Y.

    2014-06-19

    7-(Diethylamino)-coumarin-3-carboxylic acid (1) has been used as a laser dye, fluorescent label, and biomedical inhibitor in many different applications. Although this dye is typically used in the solution phase, it is prone to molecular aggregation, resulting in many inconsistent optoelectronic properties being reported in the literature. In this paper, the UV—vis absorption and fluorescence spectra of 1 are investigated in three representative solvents: cyclohexane [nonpolar and non-hydrogen bonding (NHB)], ethanol (moderately polar and hydrogen-bond accepting/donating), and DMSO (strongly polar and hydrogen-bond accepting). These experimental results, in conjunction with (time-dependent) density functional theory (DFT/TDDFT) based quantum calculations, have led to themore » identification of the J-aggregates of 1, and rationalized its different aggregation characteristic in cyclohexane in contrast to that of another similar compound, coumarin 343. We show here that these aggregates are largely responsible for the anomalous optoelectronic properties of this compound. In addition, DFT calculations and 1H NMR spectroscopy measurements suggest that the intramolecular hydrogen bond in 1 could be "opened up" in hydrogen-bond accepting solvents, affording significant molecular conformational changes and complex formation effects. The comprehensive understanding of the molecular aggregation and complex formation mechanisms of 1 acquired through this work forms a foundation for the knowledge-based molecular design of organic dyes with tailored aggregation tendencies or anti-aggregation characteristics to cater for different opapplications.« less

  2. Impact of skeletal unloading on bone formation: Role of systemic and local factors

    NASA Astrophysics Data System (ADS)

    Bikle, Daniel D.; Halloran, Bernard P.; Morey-Holton, Emily

    We have developed a model of skeletal unloading using growing rats whose hindlimbs are unweighted by tail suspension. The bones in the hindlimbs undergo a transient cessation of bone growth; when reloaded bone formation is accelerated until bone mass is restored. These changes do not occur in the normally loaded bones of the forelimbs. Associated with the fall in bone formation is a fall in 1,25(OH) 2D 3 production and osteocalcin levels. In contrast, no changes in parathyroid hormone, calcium, or corticosterone levels are seen. To examine the role of locally produced growth factors, we have measured the mRNA and protein levels of insulin like growth factor-1 (IGF-1) in bone during tail suspension. Surprisingly, both the mRNA and protein levels of IGF-1 increase during tail suspension as bone formation is reduced. Furthermore, the bones in the hindlimbs of the suspended animals develop a resistance to the growth promoting effects of both growth hormone and IGF-1 when given parenterally. Thus, the cessation of bone growth with skeletal unloading is apparently associated with a resistance to rather than failure to produce local growth factors. The cause of this resistance remains under active investigation.

  3. Importance of Highly Conserved Peptide Sites of Human Cytomegalovirus gO for Formation of the gH/gL/gO Complex

    PubMed Central

    Stegmann, Cora; Abdellatif, Mohamed E. A.; Laib Sampaio, Kerstin; Walther, Paul

    2016-01-01

    ABSTRACT The glycoprotein O (gO) is betaherpesvirus specific. Together with the viral glycoproteins H and L, gO forms a covalent trimeric complex that is part of the viral envelope. This trimer is crucial for cell-free infectivity of human cytomegalovirus (HCMV) but dispensable for cell-associated spread. We hypothesized that the amino acids that are conserved among gOs of different cytomegaloviruses are important for the formation of the trimeric complex and hence for efficient virus spread. In a mutational approach, nine peptide sites, containing all 13 highly conserved amino acids, were analyzed in the context of HCMV strain TB40-BAC4 with regard to infection efficiency and formation of the gH/gL/gO complex. Mutation of amino acids (aa) 181 to 186 or aa 193 to 198 resulted in the loss of the trimer and a complete small-plaque phenotype, whereas mutation of aa 108 or aa 249 to 254 caused an intermediate phenotype. While individual mutations of the five conserved cysteines had little impact, their relevance was revealed in a combined mutation, which abrogated both complex formation and cell-free infectivity. C343 was unique, as it was sufficient and necessary for covalent binding of gO to gH/gL. Remarkably, however, C218 together with C167 rescued infectivity in the absence of detectable covalent complex formation. We conclude that all highly conserved amino acids contribute to the function of gO to some extent but that aa 181 to 198 and cysteines 343, 218, and 167 are particularly relevant. Surprisingly, covalent binding of gO to gH/gL is required neither for its incorporation into virions nor for proper function in cell-free infection. IMPORTANCE Like all herpesviruses, the widespread human pathogen HCMV depends on glycoproteins gB, gH, and gL for entry into target cells. Additionally, gH and gL have to bind gO in a trimeric complex for efficient cell-free infection. Homologs of gO are shared by all cytomegaloviruses, with 13 amino acids being highly conserved

  4. Formation of W(3)A(1) electron-transferring flavoprotein (ETF) hydroquinone in the trimethylamine dehydrogenase x ETF protein complex.

    PubMed

    Jang, M H; Scrutton, N S; Hille, R

    2000-04-28

    The electron-transferring flavoprotein (ETF) from Methylophilus methylotrophus (sp. W(3)A(1)) exhibits unusual oxidation-reduction properties and can only be reduced to the level of the semiquinone under most circumstances (including turnover with its physiological reductant, trimethylamine dehydrogenase (TMADH), or reaction with strong reducing reagents such as sodium dithionite). In the present study, we demonstrate that ETF can be reduced fully to its hydroquinone form both enzymatically and chemically when it is in complex with TMADH. Quantitative titration of the TMADH x ETF protein complex with sodium dithionite shows that a total of five electrons are taken up by the system, indicating that full reduction of ETF occurs within the complex. The results indicate that the oxidation-reduction properties of ETF are perturbed upon binding to TMADH, a conclusion further supported by the observation of a spectral change upon formation of the TMADH x ETF complex that is due to a change in the environment of the FAD of ETF. The results are discussed in the context of ETF undergoing a conformational change during formation of the TMADH x ETF electron transfer complex, which modulates the spectral and oxidation-reduction properties of ETF such that full reduction of the protein can take place.

  5. Mercury(II) Complex Formation With Glutathione in Alkaline Aqueous Solution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mah, V.; Jalilehvand, F.

    2009-05-19

    The structure and speciation of the complexes formed between mercury(II) ions and glutathione (GSH = L-glutamyl-L-cysteinyl-glycine) have been studied for a series of alkaline aqueous solutions (C{sub Hg{sup 2+}} {approx} 18 mmol dm{sup -3} and C{sub GSH} = 40-200 mmol dm{sup -3} at pH {approx} 10.5) by means of extended X-ray absorption fine structure (EXAFS) and {sup 199}Hg NMR spectroscopy at ambient temperature. The dominant complexes are [Hg(GS){sub 2}]{sup 4-} and [Hg(GS){sub 3}]{sup 7-}, with mean Hg-S bond distances of 2.32(1) and 2.42(2) {angstrom} observed in digonal and trigonal Hg-S coordination, respectively. The proportions of the Hg{sup 2+}-glutathione complexes weremore » evaluated by fitting linear combinations of model EXAFS oscillations representing each species to the experimental EXAFS spectra. The [Hg(GS){sub 4}]{sup 10-} complex, with four sulfur atoms coordinated at a mean Hg-S bond distance of 2.52(2) {angstrom}, is present in minor amounts (<30%) in solutions containing a large excess of glutathione (C{sub GSH} {ge} 160 mmol dm{sup -3}). Comparable alkaline mercury(II) cysteine (H{sub 2}Cys) solutions were also investigated and a reduced tendency to form higher complexes was observed, because the deprotonated amino group of Cys{sup 2-} allows the stable [Hg(S,N-Cys){sub 2}]{sup 2-} chelate to form. The effect of temperature on the distribution of the Hg{sup 2+}-glutathione complexes was studied by comparing the EXAFS spectra at ambient temperature and at 25 K of a series of glycerol/water (33/67, v/v) frozen glasses with and C{sub Hg{sup 2+}} {approx} 7 mmol dm{sup -3} and C{sub GSH} = 16-81 mmol dm{sup -3}. Complexes with high Hg-S coordination numbers, [Hg(GS){sub 3}]{sup 7-} and [Hg(GS){sub 4}]{sup 10-}, became strongly favored when just a moderate excess of glutathione (C{sub GSH} {ge} 28 mmol dm{sup -3}) was used in the glassy samples, as expected for a stepwise exothermic bond formation. Addition of glycerol had no effect on the Hg

  6. Hydration of the sulfuric acid-methylamine complex and implications for aerosol formation.

    PubMed

    Bustos, Danielle J; Temelso, Berhane; Shields, George C

    2014-09-04

    The binary H2SO4-H2O nucleation is one of the most important pathways by which aerosols form in the atmosphere, and the presence of ternary species like amines increases aerosol formation rates. In this study, we focus on the hydration of a ternary system of sulfuric acid (H2SO4), methylamine (NH2CH3), and up to six waters to evaluate its implications for aerosol formation. By combining molecular dynamics (MD) sampling with high-level ab initio calculations, we determine the thermodynamics of forming H2SO4(NH2CH3)(H2O)n, where n = 0-6. Because it is a strong acid-base system, H2SO4-NH2CH3 quickly forms a tightly bound HSO4(-)-NH3CH3(+) complex that condenses water more readily than H2SO4 alone. The electronic binding energy of H2SO4-NH2CH3 is -21.8 kcal mol(-1) compared with -16.8 kcal mol(-1) for H2SO4-NH3 and -12.8 kcal mol(-1) for H2SO4-H2O. Adding one to two water molecules to the H2SO4-NH2CH3 complex is more favorable than adding to H2SO4 alone, yet there is no systematic difference for n ≥ 3. However, the average number of water molecules around H2SO4-NH2CH3 is consistently higher than that of H2SO4, and it is fairly independent of temperature and relative humidity.

  7. The Role of the Stem Cell Factor/c-kit Complex in Neurofibrormatosis.

    DTIC Science & Technology

    1997-10-01

    investigations of the Kit/ stem cell factor complex in hyperplasias of these cells. In the request for no-cost extension, several experiments were listed to be...soluble stem cell factor from the NF1 knockout Schwann cells. We also found that most neural tumors express mRNA for Kit, and also for stem cell factor.

  8. Complex formation between the protein components of methane monooxygenase from Methylosinus trichosporium OB3b. Identification of sites of component interaction.

    PubMed

    Fox, B G; Liu, Y; Dege, J E; Lipscomb, J D

    1991-01-05

    Kinetic, spectroscopic, and chemical evidence for the formation of specific catalytically essential complexes between the three protein components of the soluble form of methane monooxygenase from Methylosinus trichosporium OB3b is reported. The effects of the concentrations of the reductase and component B on the hydroxylation activity of the reconstituted enzyme system has been numerically simulated based on a kinetic model which assumes formation of multiple high affinity complexes with the hydroxylase component during catalysis. The formation of several of these complexes has been directly demonstrated. By using EPR spectroscopy, the binding of approximately 2 mol of component B/mol of hydroxylase (subunit structure (alpha beta gamma)2) is shown to significantly change the electronic environment of the mu-(H/R)-oxo-bridged binuclear iron cluster of the hydroxylase in both the mixed valent (Fe(II).Fe(III)) and fully reduced (Fe(II).Fe(II)) states. Protein-protein complexes between the reductase and component B as well as between the reductase and hydroxylase have been shown to form by monitoring quenching of the tryptophan fluorescence spectrum of either the component B (KD approximately 0.4 microM) or hydroxylase (two binding sites, KDa approximately 10 nM, KDb approximately 8 microM). The observed KD values are in agreement with the best fit values from the kinetic simulation. Through the use of the covalent zero length cross-linking reagent 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC), the binding sites of the component B and reductase were shown to be on the hydroxylase alpha and beta subunits, respectively. The alpha and beta subunits of the hydroxylase are cross-linked by EDC suggesting that they are juxtaposed. EDC also caused the rapid loss of the ability of the monomeric component B to stimulate the hydroxylation reaction suggesting that cross-linking of reactive groups on the protein surface had occurred. This effect was inhibited by the

  9. Plasmodium falciparum-infected erythrocytes induce Tissue Factor expression in endothelial cells and support the assembly of multimolecular coagulation complexes

    PubMed Central

    Francischetti, Ivo MB; Seydel, Karl B; Monteiro, Robson Q; Whitten, Richard O; Erexson, Cindy R; Noronha, Almério LL; Ostera, Graciela R.; Kamiza, Steve B; Molyneux, Malcolm E; Ward, Jerrold M; Taylor, Terrie E

    2010-01-01

    Summary Background Plasmodium falciparum malaria infects 300–500 million people every year causing 1–2 million deaths annually. Evidence of a coagulation disorder, activation of endothelial cells (EC) and increase in inflammatory cytokines are often present in malaria. Objectives We have asked whether parasitized red blood cells (pRBC) interaction with EC induces Tissue Factor expression in vitro and in vivo. The potential of phosphatidylserine-containing pRBC to support the assembly of blood coagulation complexes was also investigated. Results We demonstrate that mature forms of pRBC induce functional expression of tissue factor (TF) by endothelial cells (EC) in vitro with productive assembly of the extrinsic Xnase complex and initiation of the coagulation cascade. Late stage pRBC also support the prothrombinase and intrinsic Xnase complex formation in vitro, and may function as activated platelets in the amplification phase of the blood coagulation. Notably, postmortem brain sections obtained from P. falciparum-infected children who died from Cerebral Malaria and other causes display a consistent staining for TF in the EC. Conclusions These findings place TF expression by endothelium and the amplification of the coagulation cascade by pRBC and/or activated platelets as potentially critical steps in the pathogenesis of malaria. Furthermore, it may allow investigators to test other therapeutic alternatives targeting TF or modulators of EC function in the treatment of malaria and/or its complications. PMID:17002660

  10. The structure of a ring-opened proliferating cell nuclear antigen-replication factor C complex revealed by fluorescence energy transfer.

    PubMed

    Zhuang, Zhihao; Yoder, Bonita L; Burgers, Peter M J; Benkovic, Stephen J

    2006-02-21

    Numerous proteins that function in DNA metabolic pathways are known to interact with the proliferating cell nuclear antigen (PCNA). The important function of PCNA in stimulating various cellular activities requires its topological linkage with DNA. Loading of the circular PCNA onto duplex DNA requires the activity of a clamp-loader [replication factor C (RFC)] complex and the energy derived from ATP hydrolysis. The mechanistic and structural details regarding PCNA loading by the RFC complex are still developing. In particular, the positive identification of a long-hypothesized structure of an open clamp-RFC complex as an intermediate in loading has remained elusive. In this study, we capture an open yeast PCNA clamp in a complex with RFC through fluorescence energy transfer experiments. We also follow the topological transitions of PCNA in the various steps of the clamp-loading pathway through both steady-state and stopped-flow fluorescence studies. We find that ATP effectively drives the clamp-loading process to completion with the formation of the closed PCNA bound to DNA, whereas ATPgammaS cannot. The information derived from this work complements that obtained from previous structural and mechanistic studies and provides a more complete picture of a eukaryotic clamp-loading pathway using yeast as a paradigm.

  11. High-throughput metagenomic technologies for complex microbial community analysis: open and closed formats.

    PubMed

    Zhou, Jizhong; He, Zhili; Yang, Yunfeng; Deng, Ye; Tringe, Susannah G; Alvarez-Cohen, Lisa

    2015-01-27

    Understanding the structure, functions, activities and dynamics of microbial communities in natural environments is one of the grand challenges of 21st century science. To address this challenge, over the past decade, numerous technologies have been developed for interrogating microbial communities, of which some are amenable to exploratory work (e.g., high-throughput sequencing and phenotypic screening) and others depend on reference genes or genomes (e.g., phylogenetic and functional gene arrays). Here, we provide a critical review and synthesis of the most commonly applied "open-format" and "closed-format" detection technologies. We discuss their characteristics, advantages, and disadvantages within the context of environmental applications and focus on analysis of complex microbial systems, such as those in soils, in which diversity is high and reference genomes are few. In addition, we discuss crucial issues and considerations associated with applying complementary high-throughput molecular technologies to address important ecological questions. Copyright © 2015 Zhou et al.

  12. Formation of polyelectrolyte complexes with diethylaminoethyl dextran: charge ratio and molar mass effect.

    PubMed

    Le Cerf, Didier; Pepin, Anne Sophie; Niang, Pape Momar; Cristea, Mariana; Karakasyan-Dia, Carole; Picton, Luc

    2014-11-26

    The formation of polyelectrolyte complexes (PECs) between carboxymethyl pullulan and DEAE Dextran, was investigated, in dilute solution, with emphasis on the effect of charge density (molar ratio or pH) and molar masses. Electrophoretic mobility measurements have evidenced that insoluble PECs (neutral electrophoretic mobility) occurs for charge ratio between 0.6 (excess of polycation) and 1 (stoichiometry usual value) according to the pH. This atypical result is explained by the inaccessibility of some permanent cationic charge when screened by pH dependant cationic ones (due to the Hoffman alkylation). Isothermal titration calorimetry (ITC) indicates an endothermic formation of PEC with a binding constant around 10(5) L mol(-1). Finally asymmetrical flow field flow fractionation coupled on line with static multi angle light scattering (AF4/MALS) evidences soluble PECs with very large average molar masses and size around 100 nm, in agreement with scrambled eggs multi-association between various polyelectrolyte chains. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Heat-induced formation of myosin oligomer-soluble filament complex in high-salt solution.

    PubMed

    Shimada, Masato; Takai, Eisuke; Ejima, Daisuke; Arakawa, Tsutomu; Shiraki, Kentaro

    2015-02-01

    Heat-induced aggregation of myosin into an elastic gel plays an important role in the water-holding capacity and texture of meat products. Here, we investigated thermal aggregation of porcine myosin in high-salt solution over a wide temperature range by dynamic light scattering experiments. The myosin samples were readily dissolved in 1.0 M NaCl at 25 °C followed by dilution into various salt concentrations. The diluted solutions consistently contained both myosin monomers and soluble filaments. The filament size decreased with increasing salt concentration and temperature. High temperatures above Tm led to at least partial dissociation of soluble filaments and thermal unfolding, resulting in the formation of soluble oligomers and binding to the persistently present soluble filaments. Such a complex formation between the oligomers and filaments has never been observed. Our results provide new insight into the heat-induced myosin gelation in high-salt solution. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Formation of a PKCζ/β-catenin complex in endothelial cells promotes angiopoietin-1–induced collective directional migration and angiogenic sprouting

    PubMed Central

    Oubaha, Malika; Lin, Michelle I.; Margaron, Yoran; Filion, Dominic; Price, Emily N.; Zon, Leonard I.; Côté, Jean-François

    2012-01-01

    Angiogenic sprouting requires that cell-cell contacts be maintained during migration of endothelial cells. Angiopoietin-1 (Ang-1) and vascular endothelial growth factor act oppositely on endothelial cell junctions. We found that Ang-1 promotes collective and directional migration and, in contrast to VEGF, induces the formation of a complex formed of atypical protein kinase C (PKC)-ζ and β-catenin at cell-cell junctions and at the leading edge of migrating endothelial cells. This complex brings Par3, Par6, and adherens junction proteins at the front of migrating cells to locally activate Rac1 in response to Ang-1. The colocalization of PKCζ and β-catenin at leading edge along with PKCζ-dependent stabilization of cell-cell contacts promotes directed and collective endothelial cell migration. Consistent with these results, down-regulation of PKCζ in endothelial cells alters Ang-1–induced sprouting in vitro and knockdown in developing zebrafish results in intersegmental vessel defects caused by a perturbed directionality of tip cells and by loss of cell contacts between tip and stalk cells. These results reveal that PKCζ and β-catenin function in a complex at adherens junctions and at the leading edge of migrating endothelial cells to modulate collective and directional migration during angiogenesis. PMID:22936663

  15. Microbial Adhesion and Biofilm Formation on Microfiltration Membranes: A Detailed Characterization Using Model Organisms with Increasing Complexity

    PubMed Central

    Vanysacker, L.; Denis, C.; Declerck, P.; Piasecka, A.; Vankelecom, I. F. J.

    2013-01-01

    Since many years, membrane biofouling has been described as the Achilles heel of membrane fouling. In the present study, an ecological assay was performed using model systems with increasing complexity: a monospecies assay using Pseudomonas aeruginosa or Escherichia coli separately, a duospecies assay using both microorganisms, and a multispecies assay using activated sludge with or without spiked P. aeruginosa. The microbial adhesion and biofilm formation were evaluated in terms of bacterial cell densities, species richness, and bacterial community composition on polyvinyldifluoride, polyethylene, and polysulfone membranes. The data show that biofouling formation was strongly influenced by the kind of microorganism, the interactions between the organisms, and the changes in environmental conditions whereas the membrane effect was less important. The findings obtained in this study suggest that more knowledge in species composition and microbial interactions is needed in order to understand the complex biofouling process. This is the first report describing the microbial interactions with a membrane during the biofouling development. PMID:23986906

  16. Inhibition of the NEMO/IKKβ association complex formation, a novel mechanism associated with the NF-κB activation suppression by Withania somnifera's key metabolite withaferin A.

    PubMed

    Grover, Abhinav; Shandilya, Ashutosh; Punetha, Ankita; Bisaria, Virendra S; Sundar, Durai

    2010-12-02

    Nuclear Factor kappa B (NF-κB) is a transcription factor involved in the regulation of cell signaling responses and is a key regulator of cellular processes involved in the immune response, differentiation, cell proliferation, and apoptosis. The constitutive activation of NF-κB contributes to multiple cellular outcomes and pathophysiological conditions such as rheumatoid arthritis, asthma, inflammatory bowel disease, AIDS and cancer. Thus there lies a huge therapeutic potential beneath inhibition of NF-κB signalling pathway for reducing these chronic ailments. Withania somnifera, a reputed herb in ayurvedic medicine, comprises a large number of steroidal lactones known as withanolides which show plethora of pharmacological activities like anti- inflammatory, antitumor, antibacterial, antioxidant, anticonvulsive, and immunosuppressive. Though a few studies have been reported depicting the effect of WA (withaferin A) on suppression of NF-κB activation, the mechanism behind this is still eluding the researchers. The study conducted here is an attempt to explore NF-κB signalling pathway modulating capability of Withania somnifera's major constituent WA and to elucidate its possible mode of action using molecular docking and molecular dynamics simulations studies. Formation of active IKK (IκB kinase) complex comprising NEMO (NF-κB Essential Modulator) and IKKβ subunits is one of the essential steps for NF-κB signalling pathway, non-assembly of which can lead to prevention of the above mentioned vulnerable disorders. As observed from our semi-flexible docking analysis, WA forms strong intermolecular interactions with the NEMO chains thus building steric as well as thermodynamic barriers to the incoming IKKβ subunits, which in turn pave way to naive complex formation capability of NEMO with IKKβ. Docking of WA into active NEMO/IKKβ complex using flexible docking in which key residues of the complex were kept flexible also suggest the disruption of the active

  17. Factors affecting the formation of eutectic solid dispersions and their dissolution behavior.

    PubMed

    Vippagunta, Sudha R; Wang, Zeren; Hornung, Stefanie; Krill, Steven L

    2007-02-01

    The objective of this work was to obtain a fundamental understanding of the factors, specifically the properties of poorly water-soluble drugs and water-soluble carriers, which influence predominantly, the formation of eutectic or monotectic crystalline solid dispersion and their dissolution behavior. A theoretical model was applied on five poorly water-soluble drugs (fenofibrate, flurbiprofen, griseofulvin, naproxen, and ibuprofen) having diverse physicochemical properties and water-soluble carrier (polyethylene glycol (PEG) 8000) for the evaluation of these factors. Of these, two drugs, fenofibrate and flurbiprofen, and PEG of different molecular weights (3350, 8000, and 20000), were chosen as model drugs and carriers for further investigation. Experimental phase diagrams were constructed and dissolution testing was performed to assess the performance of the systems. The theoretical model predicted the formation of eutectic or monotectic solid dispersions of fenofibrate, griseofulvin, ibuprofen, and naproxen with PEG, holding the contribution of specific intermolecular interactions between compound and carrier to zero. In the case of the flurbiprofen-PEG eutectic system, intermolecular interactions between drug and polymer needed to be taken into consideration to predict the experimental phase diagram. The results of the current work suggest that the thermodynamic function of melting point and heat of fusion (as a measure of crystal energy of drug) plays a significant role in the formation of a eutectic system. Lipophilicity of the compound (as represented by cLog P) was also demonstrated to have an effect. Specific interactions between drug and carrier play a significant role in influencing the eutectic composition. Molar volume of the drug did not seem to have an impact on eutectic formation. The polymer molecular weight appeared to have an impact on the eutectic composition for flurbiprofen, which exhibits specific interactions with PEG, whereas no such impact

  18. C-Cl bond activation and catalytic hydrodechlorination of hexachlorobenzene by cobalt and nickel complexes with sodium formate as a reducing agent.

    PubMed

    Li, Junye; Li, Xiaoyan; Wang, Lin; Hu, Qingping; Sun, Hongjian

    2014-05-14

    A benzyne cobalt complex, Co(η(2)-C6Cl4)(PMe3)3 (2), was generated from the reaction of hexachlorobenzene with 2 equiv. of Co(PMe3)4 through selective activation of two C-Cl bonds of hexachlorobenzene. Meanwhile, the byproduct CoCl2(PMe3)3 was also confirmed by IR spectra. The cobalt(II) complex, CoCl(C6Cl5)(PMe3)3 (1), as an intermediate in the formation of aryne complex 2, was also isolated by the reaction of hexachlorobenzene with the stoichiometric amount of Co(PMe3)4. Complex 2 could be obtained by the reaction of 1 with Co(PMe3)4. Under similar reaction conditions, the reaction of Ni(PMe3)4 with hexachlorobenzene afforded only a mono-(C-Cl) bond activation nickel(II) complex, NiCl(C6H5)(PMe3)2 (5). The expected benzyne nickel complex was not formed. The structures of complexes 2 and 5 were determined by X-ray single crystal diffraction. Successful selective hydrodechlorinations of hexachlorobenzene were studied and in the presence of Co(PMe3)4 or Ni(PMe3)4 as catalysts and sodium formate as a reducing agent pentachlorobenzene and 1,2,4,5-tetrachlorobenzene were obtained. The catalytic hydrodechlorination mechanism is proposed and discussed.

  19. A cytokine axis regulates elastin formation and degradation

    PubMed Central

    Sproul, Erin P.; Argraves, W. Scott

    2013-01-01

    Underlying the dynamic regulation of tropoelastin expression and elastin formation in development and disease are transcriptional and post-transcriptional mechanisms that have been the focus of much research. Of particular importance is the cytokine–governed elastin regulatory axis in which the pro-elastogenic activities of transforming growth factor β-1 (TGFβ1) and insulin-like growth factor-I (IGF-I) are opposed by anti-elastogenic activities of basic fibroblast growth factor (bFGF/FGF-2), heparin-binding epidermal growth factor-like growth factor (HB-EGF), EGF, PDGF-BB, TGFα, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β and noncanonical TGFβ1 signaling. A key mechanistic feature of the regulatory axis is that cytokines influence elastin formation through effects on the cell cycle involving control of cyclin–cyclin dependent kinase complexes and activation of the Ras/MEK/ERK signaling pathway. In this article we provide an overview of the major cytokines/growth factors that modulate elastogenesis and describe the underlying molecular mechanisms for their action on elastin production. PMID:23160093

  20. The mechanism of nickel ferrite formation by glow discharge effect

    NASA Astrophysics Data System (ADS)

    Frolova, L. A.

    2018-04-01

    The influence of various factors on the formation of nickel ferrite by the glow discharge effect has been studied. The ferritization process in the system FeSO4-NiSO4-NaOH-H2O has been studied by the methods of potentiometric titration, measurement of electrical conductivity, residual concentrations and apparent sediment volume. It has been established that the process proceeds in a multistage fashion at pH 11-12 with the formation of polyhydroxo complexes, an intermediate compound and the ferrite formation by its oxidation with active radicals.

  1. Structure of nerve growth factor complexed with the shared neurotrophin receptor p75.

    PubMed

    He, Xiao-Lin; Garcia, K Christopher

    2004-05-07

    Neurotrophins are secreted growth factors critical for the development and maintenance of the vertebrate nervous system. Neurotrophins activate two types of cell surface receptors, the Trk receptor tyrosine kinases and the shared p75 neurotrophin receptor. We have determined the 2.4 A crystal structure of the prototypic neurotrophin, nerve growth factor (NGF), complexed with the extracellular domain of p75. Surprisingly, the complex is composed of an NGF homodimer asymmetrically bound to a single p75. p75 binds along the homodimeric interface of NGF, which disables NGF's symmetry-related second p75 binding site through an allosteric conformational change. Thus, neurotrophin signaling through p75 may occur by disassembly of p75 dimers and assembly of asymmetric 2:1 neurotrophin/p75 complexes, which could potentially engage a Trk receptor to form a trimolecular signaling complex.

  2. Hydride-Meisenheimer Complex Formation and Protonation as Key Reactions of 2,4,6-Trinitrophenol Biodegradation by Rhodococcus erythropolis

    PubMed Central

    Rieger, Paul-Gerhard; Sinnwell, Volker; Preuß, Andrea; Francke, Wittko; Knackmuss, Hans-Joachim

    1999-01-01

    Biodegradation of 2,4,6-trinitrophenol (picric acid) by Rhodococcus erythropolis HLPM-1 proceeds via initial hydrogenation of the aromatic ring system. Here we present evidence for the formation of a hydride-Meisenheimer complex (anionic ς-complex) of picric acid and its protonated form under physiological conditions. These complexes are key intermediates of denitration and productive microbial degradation of picric acid. For comparative spectroscopic identification of the hydride complex, it was necessary to synthesize this complex for the first time. Spectroscopic data revealed the initial addition of a hydride ion at position 3 of picric acid. This hydride complex readily picks up a proton at position 2, thus forming a reactive species for the elimination of nitrite. Cell extracts of R. erythropolis HLPM-1 transform the chemically synthesized hydride complex into 2,4-dinitrophenol. Picric acid is used as the sole carbon, nitrogen, and energy source by R. erythropolis HLPM-1. PMID:9973345

  3. Nitrosothiol formation and protection against Fenton chemistry by nitric oxide-induced dinitrosyliron complex formation from anoxia-initiated cellular chelatable iron increase.

    PubMed

    Li, Qian; Li, Chuanyu; Mahtani, Harry K; Du, Jian; Patel, Aashka R; Lancaster, Jack R

    2014-07-18

    Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings associated with (•)NO. However, the iron source of cellular DNIC is unknown. Previous studies on this question using prolonged (•)NO exposure could be misleading due to the movement of intracellular iron among different sources. We here report that brief (•)NO exposure results in only barely detectable DNIC, but levels increase dramatically after 1-2 h of anoxia. This increase is similar quantitatively and temporally with increases in the chelatable iron, and brief (•)NO treatment prevents detection of this anoxia-induced increased chelatable iron by deferoxamine. DNIC formation is so rapid that it is limited by the availability of (•)NO and chelatable iron. We utilize this ability to selectively manipulate cellular chelatable iron levels and provide evidence for two cellular functions of endogenous DNIC formation, protection against anoxia-induced reactive oxygen chemistry from the Fenton reaction and formation by transnitrosation of protein nitrosothiols (RSNO). The levels of RSNO under these high chelatable iron levels are comparable with DNIC levels and suggest that under these conditions, both DNIC and RSNO are the most abundant cellular adducts of (•)NO. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Soil formation: Chapter 6

    USGS Publications Warehouse

    Goldhaber, Martin B.; Banwart, Steven A.

    2015-01-01

    Soil formation reflects the complex interaction of many factors, among the most important of which are (i) the nature of the soil parent material, (ii) regional climate, (iii) organisms, including humans, (iv) topography and (v) time. These processes operate in Earth's critical zone; the thin veneer of our planet where rock meets life. Understanding the operation of these soil-forming factors requires an interdisciplinary approach and is a necessary predicate to charactering soil processes and functions, mitigating soil degradation and adapting soil management to environmental change. In this chapter, we discuss how these soil-forming factors operate both singly and in concert in natural and human modified environments. We emphasize the role that soil organic matter plays in these processes to provide context for understanding the benefits that it bestows on humanity.

  5. Neonatal NET-inhibitory factor and related peptides inhibit neutrophil extracellular trap formation

    PubMed Central

    Yost, Christian C.; Schwertz, Hansjörg; Cody, Mark J.; Wallace, Jared A.; Campbell, Robert A.; Vieira-de-Abreu, Adriana; Araujo, Claudia V.; Schubert, Sebastian; Harris, Estelle S.; Rowley, Jesse W.; Rondina, Matthew T.; Koening, Curry L.; Weyrich, Andrew S.; Zimmerman, Guy A.

    2016-01-01

    Neutrophil granulocytes, also called polymorphonuclear leukocytes (PMNs), extrude molecular lattices of decondensed chromatin studded with histones, granule enzymes, and antimicrobial peptides that are referred to as neutrophil extracellular traps (NETs). NETs capture and contain bacteria, viruses, and other pathogens. Nevertheless, experimental evidence indicates that NETs also cause inflammatory vascular and tissue damage, suggesting that identifying pathways that inhibit NET formation may have therapeutic implications. Here, we determined that neonatal NET-inhibitory factor (nNIF) is an inhibitor of NET formation in umbilical cord blood. In human neonatal and adult neutrophils, nNIF inhibits key terminal events in NET formation, including peptidyl arginine deiminase 4 (PAD4) activity, neutrophil nuclear histone citrullination, and nuclear decondensation. We also identified additional nNIF-related peptides (NRPs) that inhibit NET formation. nNIFs and NRPs blocked NET formation induced by pathogens, microbial toxins, and pharmacologic agonists in vitro and in mouse models of infection and systemic inflammation, and they improved mortality in murine models of systemic inflammation, which are associated with NET-induced collateral tissue injury. The identification of NRPs as neutrophil modulators that selectively interrupt NET generation at critical steps suggests their potential as therapeutic agents. Furthermore, our results indicate that nNIF may be an important regulator of NET formation in fetal and neonatal inflammation. PMID:27599294

  6. Risk Factors for Inhibitor Formation in Hemophilia: A Prevalent Case-Control Study

    PubMed Central

    Ragni, Margaret V.; Ojeifo, Oluseyi; Feng, Jinong; Yan, Jin; Hill, Kathleen A.; Sommer, Steve S.; Trucco, Massimo N.; Brambilla, Donald J.

    2009-01-01

    Background Inhibitor formation is a major complication of hemophilia treatment. Aim In a prevalent case-control study, we evaluated blood product exposure, genotype, and HLA type on hemophilia A inhibitor formation. Methods Product exposure was extracted from medical records. Genotype was determined on stored DNA samples by detection of virtually all mutations-SSCP (DOVAM-S) and subcycling PCR. HLA typing was performed by PCR amplification and exonuclease-released fluorescence. Results Cases experienced higher intensity factor, 455 vs. 200 U per exposure, p<0.005, more frequent central nervous system (CNS) bleeding, 7 of 20 (35.0%) vs. 1 of 57 (1.7%), p=0.001, and more commonly from inhibitor families, 7 of 20 (35.0%) vs. 0 of 57 (0%), p<0.001, and African-American, 12 of 63 (19.0%) vs. 6 of 117 (5.1%), p=0.015. Among the latter, CNS bleeding was more commonly the initial bleed, 60% vs. 0%, p<0.001, and survival was shorter, 14 vs. 38 yr, p=0.025. Inhibitor formation was uncommon in those with missense mutations, 2 of 65 (3.1%) vs. 31 of 119 (26.0%), p=0.008, and unrelated to factor VIII immunogenic epitope, p=0.388, or HLA type, p>0.100. Genotype was not associated with race. Time to immune tolerance was shorter for titers < 120 vs. ≥ 120 BU/ml, 6 vs. 16 months, p<0.01, but unaffected by tolerizing dose regimen, p>0.50. Conclusions Inhibitor formation is associated with high intensity product exposure, CNS bleeding, African-American race, and low frequency of missense mutations. The ideal time to initiate prophylaxis to reduce CNS bleeding and inhibitor formation will require prospective studies. PMID:19563499

  7. Virulence factors of the Mycobacterium tuberculosis complex

    PubMed Central

    Forrellad, Marina A.; Klepp, Laura I.; Gioffré, Andrea; Sabio y García, Julia; Morbidoni, Hector R.; Santangelo, María de la Paz; Cataldi, Angel A.; Bigi, Fabiana

    2013-01-01

    The Mycobacterium tuberculosis complex (MTBC) consists of closely related species that cause tuberculosis in both humans and animals. This illness, still today, remains to be one of the leading causes of morbidity and mortality throughout the world. The mycobacteria enter the host by air, and, once in the lungs, are phagocytated by macrophages. This may lead to the rapid elimination of the bacillus or to the triggering of an active tuberculosis infection. A large number of different virulence factors have evolved in MTBC members as a response to the host immune reaction. The aim of this review is to describe the bacterial genes/proteins that are essential for the virulence of MTBC species, and that have been demonstrated in an in vivo model of infection. Knowledge of MTBC virulence factors is essential for the development of new vaccines and drugs to help manage the disease toward an increasingly more tuberculosis-free world. PMID:23076359

  8. Effects of formate binding on the quinone-iron electron acceptor complex of photosystem II.

    PubMed

    Sedoud, Arezki; Kastner, Lisa; Cox, Nicholas; El-Alaoui, Sabah; Kirilovsky, Diana; Rutherford, A William

    2011-02-01

    EPR was used to study the influence of formate on the electron acceptor side of photosystem II (PSII) from Thermosynechococcus elongatus. Two new EPR signals were found and characterized. The first is assigned to the semiquinone form of Q(B) interacting magnetically with a high spin, non-heme-iron (Fe²(+), S=2) when the native bicarbonate/carbonate ligand is replaced by formate. This assignment is based on several experimental observations, the most important of which were: (i) its presence in the dark in a significant fraction of centers, and (ii) the period-of-two variations in the concentration expected for Q(B)(•-) when PSII underwent a series of single-electron turnovers. This signal is similar but not identical to the well-know formate-modified EPR signal observed for the Q(A)(•-)Fe²(+) complex (W.F.J. Vermaas and A.W. Rutherford, FEBS Lett. 175 (1984) 243-248). The formate-modified signals from Q(A)(•-)Fe²(+) and Q(B)(•-)Fe²(+) are also similar to native semiquinone-iron signals (Q(A)(•-)Fe²(+)/Q(B)(•-)Fe²(+)) seen in purple bacterial reaction centers where a glutamate provides the carboxylate ligand to the iron. The second new signal was formed when Q(A)(•-) was generated in formate-inhibited PSII when the secondary acceptor was reduced by two electrons. While the signal is reminiscent of the formate-modified semiquinone-iron signals, it is broader and its main turning point has a major sub-peak at higher field. This new signal is attributed to the Q(A)(•-)Fe²(+) with formate bound but which is perturbed when Q(B) is fully reduced, most likely as Q(B)H₂ (or possibly Q(B)H(•-) or Q(B)(²•-)). Flash experiments on formate-inhibited PSII monitoring these new EPR signals indicate that the outcome of charge separation on the first two flashes is not greatly modified by formate. However on the third flash and subsequent flashes, the modified Q(A)(•-)Fe²(+)Q(B)H₂ signal is trapped in the EPR experiment and there is a marked

  9. The dual-function chaperone HycH improves assembly of the formate hydrogenlyase complex.

    PubMed

    Lindenstrauß, Ute; Skorupa, Philipp; McDowall, Jennifer S; Sargent, Frank; Pinske, Constanze

    2017-08-11

    The assembly of multi-protein complexes requires the concerted synthesis and maturation of its components and subsequently their co-ordinated interaction. The membrane-bound formate hydrogenlyase (FHL) complex is the primary hydrogen-producing enzyme in Escherichia coli and is composed of seven subunits mostly encoded within the hycA-I operon for [NiFe]-hydrogenase-3 (Hyd-3). The HycH protein is predicted to have an accessory function and is not part of the final structural FHL complex. In this work, a mutant strain devoid of HycH was characterised and found to have significantly reduced FHL activity due to the instability of the electron transfer subunits. HycH was shown to interact specifically with the unprocessed species of HycE, the catalytic hydrogenase subunit of the FHL complex, at different stages during the maturation and assembly of the complex. Variants of HycH were generated with the aim of identifying interacting residues and those that influence activity. The R70/71/K72, the Y79, the E81 and the Y128 variant exchanges interrupt the interaction with HycE without influencing the FHL activity. In contrast, FHL activity, but not the interaction with HycE, was negatively influenced by H37 exchanges with polar residues. Finally, a HycH Y30 variant was unstable. Surprisingly, an overlapping function between HycH with its homologous counterpart HyfJ from the operon encoding [NiFe]-hydrogenase-4 (Hyd-4) was identified and this is the first example of sharing maturation machinery components between Hyd-3 and Hyd-4 complexes. The data presented here show that HycH has a novel dual role as an assembly chaperone for a cytoplasmic [NiFe]-hydrogenase. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  10. The effect of ligand efficacy on the formation and stability of a GPCR-G protein complex

    PubMed Central

    Yao, Xiao Jie; Vélez Ruiz, Gisselle; Whorton, Matthew R.; Rasmussen, Søren G. F.; DeVree, Brian T.; Deupi, Xavier; Sunahara, Roger K.; Kobilka, Brian

    2009-01-01

    G protein-coupled receptors (GPCRs) mediate the majority of physiologic responses to hormones and neurotransmitters. However, many GPCRs exhibit varying degrees of agonist-independent G protein activation. This phenomenon is referred to as basal or constitutive activity. For many of these GPCRs, drugs classified as inverse agonists can suppress basal activity. There is a growing body of evidence that basal activity is physiologically relevant, and the ability of a drug to inhibit basal activity may influence its therapeutic properties. However, the molecular mechanism for basal activation and inhibition of basal activity by inverse agonists is poorly understood and difficult to study, because the basally active state is short-lived and represents a minor fraction of receptor conformations. Here, we investigate basal activation of the G protein Gs by the β2 adrenergic receptor (β2AR) by using purified receptor reconstituted into recombinant HDL particles with a stoichiometric excess of Gs. The β2AR is site-specifically labeled with a small, environmentally sensitive fluorophore enabling direct monitoring of agonist- and Gs-induced conformational changes. In the absence of an agonist, the β2AR and Gs can be trapped in a complex by enzymatic depletion of guanine nucleotides. Formation of the complex is enhanced by the agonist isoproterenol, and it rapidly dissociates on exposure to concentrations of GTP and GDP found in the cytoplasm. The inverse agonist ICI prevents formation of the β2AR-Gs complex, but has little effect on preformed complexes. These results provide insights into G protein-induced conformational changes in the β2AR and the structural basis for ligand efficacy. PMID:19470481

  11. [Complex formation between alpha-chymotrypsin and block copolymers based on ethylene and propylene oxide, induced by high pressure].

    PubMed

    Topchieva, I N; Sorokina, E M; Kurganov, B I; Zhulin, V M; Makarova, Z G

    1996-06-01

    A new method of formation of non-covalent adducts based on an amphiphilic diblock copolymer of ethylene and propylene oxides with molecular mass of 2 kDa and alpha-chymotrypsin (ChT) under high pressure, has been developed. The composition of the complexes corresponds to seven polymer molecules per one ChT molecule in the pressure range of 1.1 to 400 MPa. The complexes fully retain the catalytic activity. Kinetic constants (Km and kcat) for enzymatic hydrolysis of N-benzoyl-L-tyrosine ethyl ester catalyzed by the complexes are identical with the corresponding values for native ChT. Analysis of kinetics of thermal inactivation of the complexes revealed that the constant of the rate of the slow inactivation step is markedly lower than for ChT.

  12. Investigating the Effect of Complexity Factors in Stoichiometry Problems Using Logistic Regression and Eye Tracking

    ERIC Educational Resources Information Center

    Tang, Hui; Kirk, John; Pienta, Norbert J.

    2014-01-01

    This paper includes two experiments, one investigating complexity factors in stoichiometry word problems, and the other identifying students' problem-solving protocols by using eye-tracking technology. The word problems used in this study had five different complexity factors, which were randomly assigned by a Web-based tool that we developed. The…

  13. Mechanistic study of intertypic nucleoprotein complex formation and its inhibitory effect toward influenza A virus.

    PubMed

    Narkpuk, Jaraspim; Jaru-Ampornpan, Peera; Subali, Theressa; Bertulfo, Fatima Carla T; Wongthida, Phonphimon; Jongkaewwattana, Anan

    2015-11-01

    Co-infection of influenza A and B viruses (IAV and IBV) results in marked decreases in IAV replication. Multiple mechanisms have been proposed for this phenomenon. Recently, we reported that IBV nucleoprotein (BNP) alone can suppress IAV replication and proposed an inhibition model in which BNP binds IAV nucleoprotein (ANP) and disrupts IAV polymerase complexes. Here, using mutagenesis and co-immunoprecipitation, we determined the protein motifs mediating the intertypic ANP-BNP complex and showed that it specifically interferes with ANP׳s interaction with the PB2 subunit of the IAV polymerase but not with the other subunit PB1. We further demonstrated that BNP only suppresses growth of IAVs but not other RNA viruses. However, different IAV strains display varied sensitivity toward the BNP׳s inhibitory effect. Together, our data provide mechanistic insights into intertypic nucleoprotein complex formation and highlight the role of BNP as a potential broad-spectrum anti-IAV agent. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Formation of multiple focal spots using a high NA lens with a complex spiral phase mask

    NASA Astrophysics Data System (ADS)

    Lalithambigai, K.; Anbarasan, P. M.; Rajesh, K. B.

    2014-07-01

    The formation of a transversally polarized beam by transmitting a tightly focused double-ring-shaped azimuthally polarized beam through a complex spiral phase mask and high numerical aperture lens is presented based on vector diffraction theory. The generation of transversally polarized focal spot segment splitting and multiple focal spots is illustrated numerically. Moreover, we found that a properly designed complex spiral phase mask can move the focal spots along the optical axis in the z direction. Therefore, one can achieve a focal segment of two, three or multiple completely transversely polarized focal spots, which finds applications in optical trapping and in material processing technologies.

  15. The 70 S monosome accumulation and in vitro initiation complex formation by Escherichia coli ribosomes at 5 C. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Broeze, R. J.; Pope, D. H.

    1978-01-01

    The inhibition of translation which is observed after shifting Escherichia coli to low temperature was investigated. 70 S ribosomes were isolated from E. coli 8 hours after a shift to 5 C synthesized protein in the absence of added mRNA (i.e., endogenous protein synthesis by 70 S monosomes) at a rate which was three times greater than the rate of endogenous protein synthesis by 70 S ribosomes which were isolated at the time of the shift to 5 C. Calculations based on the rates of endogenous protein synthesis and polyphenylalanine synthesis indicate that 70 S monosomes comprise only 0.1% of the total E. coli 70 S ribosome population after 8 hours at 5 c. Experiments designed to test initiation complex formation on ApUpG or formaldehyde treated MS-2 viral RNA demonstrated that, although the rate of formation of 30 S initiation complexes was not inhibited, the rate of formation of active 70 S initiation complexes, able to react with puromycin, was inhibited to a great extent at 5 C. A model depicting the effects of low temperature on the E. coli translation system is proposed.

  16. Complex organic molecules during low-mass star formation: Pilot survey results

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Öberg, Karin I.; Graninger, Dawn; Lauck, Trish, E-mail: koberg@cfa.harvard.edu

    Complex organic molecules (COMs) are known to be abundant toward some low-mass young stellar objects (YSOs), but how these detections relate to typical COM abundance are not yet understood. We aim to constrain the frequency distribution of COMs during low-mass star formation, beginning with this pilot survey of COM lines toward six embedded YSOs using the IRAM 30 m Telescope. The sample was selected from the Spitzer c2d ice sample and covers a range of ice abundances. We detect multiple COMs, including CH{sub 3}CN, toward two of the YSOs, and tentatively toward a third. Abundances with respect to CH{sub 3}OHmore » vary between 0.7% and 10%. This sample is combined with previous COM observations and upper limits to obtain a frequency distributions of CH{sub 3}CN, HCOOCH{sub 3}, CH{sub 3}OCH{sub 3}, and CH{sub 3}CHO. We find that for all molecules more than 50% of the sample have detections or upper limits of 1%-10% with respect to CH{sub 3}OH. Moderate abundances of COMs thus appear common during the early stages of low-mass star formation. A larger sample is required, however, to quantify the COM distributions, as well as to constrain the origins of observed variations across the sample.« less

  17. A Low-Complexity Subgroup Formation with QoS-Aware for Enhancing Multicast Services in LTE Networks

    NASA Astrophysics Data System (ADS)

    Algharem, M.; Omar, M. H.; Rahmat, R. F.; Budiarto, R.

    2018-03-01

    The high demand of Multimedia services on in Long Term Evolution (LTE) and beyond networks forces the networks operators to find a solution that can handle the huge traffic. Along with this, subgroup formation techniques are introduced to overcome the limitations of the Conventional Multicast Scheme (CMS) by splitting the multicast users into several subgroups based on the users’ channels quality signal. However, finding the best subgroup configuration with low complexity is need more investigations. In this paper, an efficient and simple subgroup formation mechanisms are proposed. The proposed mechanisms take the transmitter MAC queue in account. The effectiveness of the proposed mechanisms is evaluated and compared with CMS in terms of throughput, fairness, delay, Block Error Rate (BLER).

  18. RIT1 controls actin dynamics via complex formation with RAC1/CDC42 and PAK1.

    PubMed

    Meyer Zum Büschenfelde, Uta; Brandenstein, Laura Isabel; von Elsner, Leonie; Flato, Kristina; Holling, Tess; Zenker, Martin; Rosenberger, Georg; Kutsche, Kerstin

    2018-05-01

    RIT1 belongs to the RAS family of small GTPases. Germline and somatic RIT1 mutations have been identified in Noonan syndrome (NS) and cancer, respectively. By using heterologous expression systems and purified recombinant proteins, we identified the p21-activated kinase 1 (PAK1) as novel direct effector of RIT1. We found RIT1 also to directly interact with the RHO GTPases CDC42 and RAC1, both of which are crucial regulators of actin dynamics upstream of PAK1. These interactions are independent of the guanine nucleotide bound to RIT1. Disease-causing RIT1 mutations enhance protein-protein interaction between RIT1 and PAK1, CDC42 or RAC1 and uncouple complex formation from serum and growth factors. We show that the RIT1-PAK1 complex regulates cytoskeletal rearrangements as expression of wild-type RIT1 and its mutant forms resulted in dissolution of stress fibers and reduction of mature paxillin-containing focal adhesions in COS7 cells. This effect was prevented by co-expression of RIT1 with dominant-negative CDC42 or RAC1 and kinase-dead PAK1. By using a transwell migration assay, we show that RIT1 wildtype and the disease-associated variants enhance cell motility. Our work demonstrates a new function for RIT1 in controlling actin dynamics via acting in a signaling module containing PAK1 and RAC1/CDC42, and highlights defects in cell adhesion and migration as possible disease mechanism underlying NS.

  19. RIT1 controls actin dynamics via complex formation with RAC1/CDC42 and PAK1

    PubMed Central

    von Elsner, Leonie; Flato, Kristina; Holling, Tess; Zenker, Martin; Rosenberger, Georg

    2018-01-01

    RIT1 belongs to the RAS family of small GTPases. Germline and somatic RIT1 mutations have been identified in Noonan syndrome (NS) and cancer, respectively. By using heterologous expression systems and purified recombinant proteins, we identified the p21-activated kinase 1 (PAK1) as novel direct effector of RIT1. We found RIT1 also to directly interact with the RHO GTPases CDC42 and RAC1, both of which are crucial regulators of actin dynamics upstream of PAK1. These interactions are independent of the guanine nucleotide bound to RIT1. Disease-causing RIT1 mutations enhance protein-protein interaction between RIT1 and PAK1, CDC42 or RAC1 and uncouple complex formation from serum and growth factors. We show that the RIT1-PAK1 complex regulates cytoskeletal rearrangements as expression of wild-type RIT1 and its mutant forms resulted in dissolution of stress fibers and reduction of mature paxillin-containing focal adhesions in COS7 cells. This effect was prevented by co-expression of RIT1 with dominant-negative CDC42 or RAC1 and kinase-dead PAK1. By using a transwell migration assay, we show that RIT1 wildtype and the disease-associated variants enhance cell motility. Our work demonstrates a new function for RIT1 in controlling actin dynamics via acting in a signaling module containing PAK1 and RAC1/CDC42, and highlights defects in cell adhesion and migration as possible disease mechanism underlying NS. PMID:29734338

  20. PriC-mediated DNA replication restart requires PriC complex formation with the single-stranded DNA-binding protein.

    PubMed

    Wessel, Sarah R; Marceau, Aimee H; Massoni, Shawn C; Zhou, Ruobo; Ha, Taekjip; Sandler, Steven J; Keck, James L

    2013-06-14

    Frequent collisions between cellular DNA replication complexes (replisomes) and obstacles such as damaged DNA or frozen protein complexes make DNA replication fork progression surprisingly sporadic. These collisions can lead to the ejection of replisomes prior to completion of replication, which, if left unrepaired, results in bacterial cell death. As such, bacteria have evolved DNA replication restart mechanisms that function to reload replisomes onto abandoned DNA replication forks. Here, we define a direct interaction between PriC, a key Escherichia coli DNA replication restart protein, and the single-stranded DNA-binding protein (SSB), a protein that is ubiquitously associated with DNA replication forks. PriC/SSB complex formation requires evolutionarily conserved residues from both proteins, including a pair of Arg residues from PriC and the C terminus of SSB. In vitro, disruption of the PriC/SSB interface by sequence changes in either protein blocks the first step of DNA replication restart, reloading of the replicative DnaB helicase onto an abandoned replication fork. Consistent with the critical role of PriC/SSB complex formation in DNA replication restart, PriC variants that cannot bind SSB are non-functional in vivo. Single-molecule experiments demonstrate that PriC binding to SSB alters SSB/DNA complexes, exposing single-stranded DNA and creating a platform for other proteins to bind. These data lead to a model in which PriC interaction with SSB remodels SSB/DNA structures at abandoned DNA replication forks to create a DNA structure that is competent for DnaB loading.

  1. Formation and stability of water-soluble, molecular polyelectrolyte complexes: effects of charge density, mixing ratio, and polyelectrolyte concentration.

    PubMed

    Shovsky, Alexander; Varga, Imre; Makuska, Ricardas; Claesson, Per M

    2009-06-02

    The formation of complexes with stoichiometric (1:1) as well as nonstoichiometric (2:1) and (1:2) compositions between oppositely charged synthetic polyelectrolytes carrying strong ionic groups and significantly different molecular weights is reported in this contribution. Poly(sodium styrenesulfonate) (NaPSS) was used as polyanion, and a range of copolymers with various molar ratios of the poly(methacryloxyethyltrimethylammonium) chloride, poly(METAC), and the nonionic poly(ethylene oxide) ether methacrylate, poly(PEO45MEMA), were used as polycations. Formation and stability of PECs have been investigated by dynamic and static light scattering (LS), turbidity, and electrophoretic mobility measurements as a function of polyelectrolyte solution concentration, charge density of the cationic polyelectrolyte, and mixing ratio. The data obtained demonstrate that in the absence of PEO45 side chains the 100% charged polymer (polyMETAC) formed insoluble PECs with PSS that precipitate from solution when exact stoichiometry is achieved. In nonstoichiometric complexes (1:2) and (2:1) large colloidally stable aggregates were formed. The presence of even a relatively small amount of PEO45 side chains (25%) in the cationic copolymer was sufficient for preventing precipitation of the formed stoichiometric and nonstoichiometric complexes. These PEC's are sterically stabilized by the PEO45 chains. By further increasing the PEO45 side-chain content (50 and 75%) of the cationic copolymer, small, water-soluble molecular complexes could be formed. The data suggest that PSS molecules and the charged backbone of the cationic brush form a compact core, and with sufficiently high PEO45 chain density (above 25%) molecular complexes are formed that are stable over prolonged times.

  2. NUCLEAR FACTOR-Y: still complex after all these years?

    PubMed

    Myers, Zachary A; Holt, Ben F

    2018-06-11

    The NUCLEAR FACTOR-Y (NF-Y) families of transcription factors are important regulators of plant development and physiology. Though NF-Y regulatory roles have recently been suggested for numerous aspects of plant biology, their roles in flowering time, early seedling development, stress responses, hormone signaling, and nodulation are the best characterized. The past few years have also seen significant advances in our understanding of the mechanistic function of the NF-Y, and as such, increasingly complex and interesting questions are now more approachable. This review will primarily focus on these developmental, physiological, and mechanistic roles of the NF-Y in recent research. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Bimetallic cooperative effect on O-O bond formation: copper polypyridyl complexes as water oxidation catalyst.

    PubMed

    Su, Xiao-Jun; Zheng, Chu; Hu, Qin-Qin; Du, Hao-Yi; Liao, Rong-Zhen; Zhang, Ming-Tian

    2018-06-13

    The performance of water oxidation catalysis by a Cu-based polypyridyl complex, [CuII(TPA)(OH2)]2+ (1H; TPA = tris-(pyridylmethyl)amine), has been investigated in neutral aqueous solution by electrochemical methods. Compared with our previously reported binuclear catalyst, [(BPMAN)(CuII)2(μ-OH)]3+ (2; BPMAN = 2,7-[bis(2-pyridylmethyl)aminomethyl]-1,8-naphthyridine), mononuclear catalyst 1 has a higher overpotential and lower catalytic activity toward water oxidation under the same conditions. Experimental results revealed that the O-O bond formation occurred via a water nucleophilic attack mechanism in which formal CuIV(O) is proposed as a key intermediate for the mononuclear catalyst 1H. In contrast, for the binuclear catalyst, O-O bond formation was facilitated by bimetallic cooperation between the two CuIII centers.

  4. Study on Flake Formation Behavior and Its Influence Factors in Cr5 Steel

    PubMed Central

    Chen, Huitao; Zhao, Wu; Yan, Liang

    2018-01-01

    A flake is a crack that is induced by trapped hydrogen within steel. To study its formation mechanism, previous studies mostly focused on the formation process and magnitude of hydrogen pressure in hydrogen traps such as cavities and cracks. However, according to recent studies, the hydrogen leads to the decline of the mechanical properties of steel, which is known as hydrogen embrittlement, is another reason for flake formation. In addition, the phenomenon of stress induced hydrogen uphill diffusion should not be neglected. All of the three behaviors are at work simultaneously. In order to further explore the formation mechanism of flakes in steel, the process of flake initiation and growth were studied with the following three coupling factors: trap hydrogen pressure, hydrogen embrittlement, and stress induced hydrogen re-distribution. The analysis model was established using the finite element method, and a crack whose radius is 0.5 mm was set in its center. The cohesive method and Bilinear Traction Separate Law (BTSL) were used to address the coupling effect. The results show that trap hydrogen pressure is the main driving force for flake formation. After the high hydrogen pressure was generated around the trap, a stress field formed. In addition, the trap is the center of stress concentration. Then, hydrogen is concentrated in a distribution around this trap, and most of the steel mechanical properties are reduced. The trap size is a key factor for defining the critical hydrogen content for flake formation and propagation. However, when the trap size exceeds the specified value, the critical hydrogen content does not change any more. As for the crack whose radius is 0.5 mm, the critical hydrogen content of Cr5VMo steel is 2.2 ppm, which is much closer to the maximum safe hydrogen concentration of 2.0 ppm used in China. The work presented in this article increases our understanding of flake formation and propagation mechanisms in steel. PMID:29702610

  5. Prevalence of difficult venous access and associated risk factors in highly complex hospitalised patients.

    PubMed

    Armenteros-Yeguas, Victoria; Gárate-Echenique, Lucía; Tomás-López, Maria Aranzazu; Cristóbal-Domínguez, Estíbaliz; Moreno-de Gusmão, Breno; Miranda-Serrano, Erika; Moraza-Dulanto, Maria Inmaculada

    2017-12-01

    To estimate the prevalence of difficult venous access in complex patients with multimorbidity and to identify associated risk factors. In highly complex patients, factors like ageing, the need for frequent use of irritant medication and multiple venous catheterisations to complete treatment could contribute to exhaustion of venous access. A cross-sectional study was conducted. 'Highly complex' patients (n = 135) were recruited from March 2013-November 2013. The main study variable was the prevalence of difficult venous access, assessed using one of the following criteria: (1) a history of difficulties obtaining venous access based on more than two attempts to insert an intravenous line and (2) no visible or palpable veins. Other factors potentially associated with the risk of difficult access were also measured (age, gender and chronic illnesses). Univariate analysis was performed for each potential risk factor. Factors with p < 0·2 were then included in multivariable logistic regression analysis. Odds ratios were also calculated. The prevalence of difficult venous access was 59·3%. The univariate logistic regression analysis indicated that gender, a history of vascular access complications and osteoarticular disease were significantly associated with difficult venous access. The multivariable logistic regression showed that only gender was an independent risk factor and the odds ratios was 2·85. The prevalence of difficult venous access is high in this population. Gender (female) is the only independent risk factor associated with this. Previous history of several attempts at catheter insertion is an important criterion in the assessment of difficult venous access. The prevalence of difficult venous access in complex patients is 59·3%. Significant risk factors include being female and a history of complications related to vascular access. © 2017 John Wiley & Sons Ltd.

  6. Protein complex formation and intranuclear dynamics of NAC1 in cancer cells.

    PubMed

    Nakayama, Naomi; Kato, Hiroaki; Sakashita, Gyosuke; Nariai, Yuko; Nakayama, Kentaro; Kyo, Satoru; Urano, Takeshi

    2016-09-15

    Nucleus accumbens-associated protein 1 (NAC1) is a cancer-related transcription regulator protein that is also involved in the pluripotency and differentiation of embryonic stem cells. NAC1 is overexpressed in various carcinomas including ovarian, cervical, breast, and pancreatic carcinomas. NAC1 knock-down was previously shown to result in the apoptosis of ovarian cancer cell lines and to rescue their sensitivity to chemotherapy, suggesting that NAC1 may be a potential therapeutic target, but protein complex formation and the dynamics of intranuclear NAC1 in cancer cells remain poorly understood. In this study, analysis of HeLa cell lysates by fast protein liquid chromatography (FPLC) on a sizing column showed that the NAC1 peak corresponded to an apparent molecular mass of 300-500 kDa, which is larger than the estimated molecular mass (58 kDa) of the protein. Furthermore, live cell photobleaching analyses with green fluorescent protein (GFP)-fused NAC1 proteins revealed the intranuclear dynamics of NAC1. Collectively our results demonstrate that NAC1 forms a protein complex to function as a transcriptional regulator in cancer cells. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Formation and Atmosphere of Complex Organic Molecules of the HH 212 Protostellar Disk

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Chin-Fei; Ho, Paul T. P.; Hirano, Naomi

    HH 212 is a nearby (400 pc) Class 0 protostellar system recently found to host a “hamburger”-shaped dusty disk with a radius of ∼60 au, deeply embedded in an infalling-rotating flattened envelope. We have spatially resolved this envelope-disk system with the Atacama Large Millimeter/submillimeter Array at up to ∼16 au (0.″04) resolution. The envelope is detected in HCO{sup +} J = 4–3 down to the dusty disk. Complex organic molecules (COMs) and doubly deuterated formaldehyde (D{sub 2}CO) are detected above and below the dusty disk within ∼40 au of the central protostar. The COMs are methanol (CH{sub 3}OH), deuterated methanolmore » (CH{sub 2}DOH), methyl mercaptan (CH{sub 3}SH), and formamide (NH{sub 2}CHO, a prebiotic precursor). We have modeled the gas kinematics in HCO{sup +} and COMs and found a centrifugal barrier (CB) at a radius of ∼44 au, within which a Keplerian rotating disk is formed. This indicates that HCO{sup +} traces the infalling-rotating envelope down to the CB and COMs trace the atmosphere of a Keplerian rotating disk within the CB. The COMs are spatially resolved for the first time, both radially and vertically, in the atmosphere of a disk in the earliest, Class 0 phase of star formation. Our spatially resolved observations of COMs favor their formation in the disk rather than a rapidly infalling (warm) inner envelope. The abundances and spatial distributions of the COMs provide strong constraints on models of their formation and transport in low-mass star formation.« less

  8. STAR FORMATION ACTIVITY IN THE GALACTIC H II COMPLEX S255-S257

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ojha, D. K.; Ghosh, S. K.; Samal, M. R.

    We present results on the star formation activity of an optically obscured region containing an embedded cluster (S255-IR) and molecular gas between two evolved H II regions, S255 and S257. We have studied the complex using optical and near-infrared (NIR) imaging, optical spectroscopy, and radio continuum mapping at 15 GHz, along with Spitzer-IRAC results. We found that the main exciting sources of the evolved H II regions S255 and S257 and the compact H II regions associated with S255-IR are of O9.5-B3 V nature, consistent with previous observations. Our NIR observations reveal 109 likely young stellar object (YSO) candidates inmore » an area of {approx}4.'9 x 4.'9 centered on S255-IR, which include 69 new YSO candidates. To see the global star formation, we constructed the V - I/V diagram for 51 optically identified IRAC YSOs in an area of {approx}13' x 13' centered on S255-IR. We suggest that these YSOs have an approximate age between 0.1 and 4 Myr, indicating a non-coeval star formation. Using spectral energy distribution models, we constrained physical properties and evolutionary status of 31 and 16 YSO candidates outside and inside the gas ridge, respectively. The models suggest that the sources associated with the gas ridge are younger (mean age {approx}1.2 Myr) than the sources outside the gas ridge (mean age {approx}2.5 Myr). The positions of the young sources inside the gas ridge at the interface of the H II regions S255 and S257 favor a site of induced star formation.« less

  9. IN VITRO AND IN VIVO ACTIVITY OF A LYMPHOCYTE AND IMMUNE COMPLEX-DEPENDENT CHEMOTACTIC FACTOR FOR EOSINOPHILS

    PubMed Central

    Cohen, Stanley; Ward, Peter A.

    1971-01-01

    When cultured in the presence of specific antigen, lymphocytes from delayed-hypersensitive guinea pigs release a number of biologically active substances into the culture medium. Such active supernatants can react with immune complexes in vitro to generate a factor which is chemotactic for eosinophils. The factor involved is unique, since previously described chemotactic factors for other cell types require for their generation either immune complexes or substances released into lymphocyte culture, but not both. In the case of the eosinophil chemotactic factor, the interaction between the substance elaborated by the lymphocytes and the immune complexes appears to be specific in that the immune complexes must contain the same antigen as that used to activate the lymphocyte cultures. Although this factor was generated in an in vitro system, it has been shown to possess in vivo as well as in vitro activity. It is therefore possible that this factor may be of biological significance in situations where eosinophils are participants in inflammatory or immunologic reactions. PMID:5099667

  10. Regulation of synaptic vesicle recycling by complex formation between intersectin 1 and the clathrin adaptor complex AP2

    PubMed Central

    Pechstein, Arndt; Bacetic, Jelena; Vahedi-Faridi, Ardeschir; Gromova, Kira; Sundborger, Anna; Tomlin, Nikolay; Krainer, Georg; Vorontsova, Olga; Schäfer, Johannes G.; Owe, Simen G.; Cousin, Michael A.; Saenger, Wolfram; Shupliakov, Oleg; Haucke, Volker

    2010-01-01

    Clathrin-mediated synaptic vesicle (SV) recycling involves the spatiotemporally controlled assembly of clathrin coat components at phosphatidylinositiol (4, 5)-bisphosphate [PI(4,5)P2]-enriched membrane sites within the periactive zone. Such spatiotemporal control is needed to coordinate SV cargo sorting with clathrin/AP2 recruitment and to restrain membrane fission and synaptojanin-mediated uncoating until membrane deformation and clathrin coat assembly are completed. The molecular events underlying these control mechanisms are unknown. Here we show that the endocytic SH3 domain-containing accessory protein intersectin 1 scaffolds the endocytic process by directly associating with the clathrin adaptor AP2. Acute perturbation of the intersectin 1-AP2 interaction in lamprey synapses in situ inhibits the onset of SV recycling. Structurally, complex formation can be attributed to the direct association of hydrophobic peptides within the intersectin 1 SH3A-B linker region with the “side sites” of the AP2 α- and β-appendage domains. AP2 appendage association of the SH3A-B linker region inhibits binding of the inositol phosphatase synaptojanin 1 to intersectin 1. These data identify the intersectin-AP2 complex as an important regulator of clathrin-mediated SV recycling in synapses. PMID:20160082

  11. Method for determining formation quality factor from well log data and its application to seismic reservoir characterization

    DOEpatents

    Walls, Joel; Taner, M. Turhan; Dvorkin, Jack

    2006-08-08

    A method for seismic characterization of subsurface Earth formations includes determining at least one of compressional velocity and shear velocity, and determining reservoir parameters of subsurface Earth formations, at least including density, from data obtained from a wellbore penetrating the formations. A quality factor for the subsurface formations is calculated from the velocity, the density and the water saturation. A synthetic seismogram is calculated from the calculated quality factor and from the velocity and density. The synthetic seismogram is compared to a seismic survey made in the vicinity of the wellbore. At least one parameter is adjusted. The synthetic seismogram is recalculated using the adjusted parameter, and the adjusting, recalculating and comparing are repeated until a difference between the synthetic seismogram and the seismic survey falls below a selected threshold.

  12. Complement activating properties of complexes containing rheumatoid factor in synovial fluids and sera from patients with rheumatoid arthritis.

    PubMed Central

    Elson, C J; Carter, S D; Cottrell, B J; Scott, D G; Bacon, P A; Wallington, T B

    1985-01-01

    The relationship between complexes containing rheumatoid factor and complexes activating complement was examined in synovial fluids and sera from patients with rheumatoid arthritis (RA). In each case this was performed by quantifying the amount of rheumatoid factor bound by solid phase Fab'2 anti-C3 and/or solid phase conglutinin. Both anti-C3 coated and conglutinin coated microtitre plates bound high levels of complexes containing rheumatoid factor from sera of RA patients with vasculitis. Unexpectedly, these complexes were detected in synovial fluids from only a minority of RA patients with synovitis. However, RA synovial fluids did contain other complexes as shown by the presence of complement consuming activity, C1q binding material and immunoglobulin attaching to conglutinin. It is considered that in RA synovial fluids the complexes containing RF and those activating complement are not necessarily the same whilst in vasculitic sera the complexes containing rheumatoid factor also activate complement. PMID:3978872

  13. Photo-induced living radical polymerization of acrylates utilizing a discrete copper(II)-formate complex.

    PubMed

    Anastasaki, Athina; Nikolaou, Vasiliki; Brandford-Adams, Francesca; Nurumbetov, Gabit; Zhang, Qiang; Clarkson, Guy J; Fox, David J; Wilson, Paul; Kempe, Kristian; Haddleton, David M

    2015-04-04

    A photo-polymerization protocol, utilizing a pre-formed and well-characterized Cu(II) formate complex, [Cu(Me6-Tren)(O2CH)](ClO4), mediated by UV light is described. In the absence of additional reducing agents and/or photosensitizers, ppm concentrations of the oxidatively stable [Cu(Me6-Tren)(O2CH)](ClO4), furnish near-quantitative conversions within 2 h, yielding poly(acrylates) with low dispersities (∼1.10) and exceptional end-group fidelity, capable of undergoing in situ chain extension and block copolymerization.

  14. Appropriate suppression of Notch signaling by Mesp factors is essential for stripe pattern formation leading to segment boundary formation.

    PubMed

    Takahashi, Yu; Yasuhiko, Yukuto; Kitajima, Satoshi; Kanno, Jun; Saga, Yumiko

    2007-04-15

    Mesp1 and Mesp2 are homologous transcription factors that are co-expressed in the anterior presomitic mesoderm (PSM) during mouse somitogenesis. The loss of Mesp2 alone in our conventional Mesp2-null mice results in the complete disruption of somitogenesis, including segment border formation, rostro-caudal patterning and epithelialization of somitic mesoderm. This has led us to interpret that Mesp2 is solely responsible for somitogenesis. Our novel Mesp2 knock-in alleles, however, exhibit a remarkable upregulation of Mesp1. Removal of the pgk-neo cassette from the new allele leads to localization of Mesp1 and several gene expression, and somite formation in the tail region. Moreover, a reduction in the gene dosage of Mesp1 by one copy disrupts somite formation, confirming the involvement of Mesp1 in the rescue events. Furthermore, we find that activated Notch1 knock-in significantly upregulates Mesp1 expression, even in the absence of a Notch signal mediator, Psen1. This indicates that the Psen1-independent effects of activated Notch1 are mostly attributable to the induction of Mesp1. However, we have also confirmed that Mesp2 enhances the expression of the Notch1 receptor in the anterior PSM. The activation and subsequent suppression of Notch signaling might thus be a crucial event for both stripe pattern formation and boundary formation.

  15. Time Factor in the Theory of Anthropogenic Risk Prediction in Complex Dynamic Systems

    NASA Astrophysics Data System (ADS)

    Ostreikovsky, V. A.; Shevchenko, Ye N.; Yurkov, N. K.; Kochegarov, I. I.; Grishko, A. K.

    2018-01-01

    The article overviews the anthropogenic risk models that take into consideration the development of different factors in time that influence the complex system. Three classes of mathematical models have been analyzed for the use in assessing the anthropogenic risk of complex dynamic systems. These models take into consideration time factor in determining the prospect of safety change of critical systems. The originality of the study is in the analysis of five time postulates in the theory of anthropogenic risk and the safety of highly important objects. It has to be stressed that the given postulates are still rarely used in practical assessment of equipment service life of critically important systems. That is why, the results of study presented in the article can be used in safety engineering and analysis of critically important complex technical systems.

  16. Transition Organometallic Heterobimettalic Microns-Carbon Dioxide and Microns-Format Complexes in Homogeneous Carbon Dioxide Fixation

    DTIC Science & Technology

    1992-08-12

    AD-A254 538 OFFICE OF NAVAL RESEARCH FINAL REPORT FCR Contract N00014-87-K-0465 R&T Code 413j006 "Transition Organometallic Heterobimetallic ix...ransition Organometallic Heterobimetallic P-Carbon Dioxide and p-FormateComplexes in Homogeneous Carbon Dioxide Fixation 12. PERSONAL AUTHOR(S) Alan R...J. L. Shibley, and A. R. Cutler, J. Organomet. Chem. 1989,378, 421.* "Characterization of the Heterobimetallic ±(r011-C: T12 -O,O’) Carbon Dioxide

  17. The Human SepSecS-tRNASec Complex Reveals the Mechanism of Selenocysteine Formation

    PubMed Central

    Palioura, Sotiria; Sherrer, R. Lynn; Steitz, Thomas A.; Söll, Dieter; Simonović, Miljan

    2010-01-01

    Selenocysteine is the only genetically encoded amino acid in humans whose biosynthesis occurs on its cognate transfer RNA (tRNA). O-Phosphoseryl-tRNA:selenocysteinyl-tRNA synthase (SepSecS) catalyzes the final step of selenocysteine formation by a poorly understood tRNA-dependent mechanism. The crystal structure of human tRNASec in complex with SepSecS, phosphoserine, and thiophosphate, together with in vivo and in vitro enzyme assays, supports a pyridoxal phosphate–dependent mechanism of Sec-tRNASec formation. Two tRNASec molecules, with a fold distinct from other canonical tRNAs, bind to each SepSecS tetramer through their 13–base pair acceptor-TΨC arm (where Ψ indicates pseudouridine). The tRNA binding is likely to induce a conformational change in the enzyme’s active site that allows a phosphoserine covalently attached to tRNASec, but not free phosphoserine, to be oriented properly for the reaction to occur. PMID:19608919

  18. Papillae formation on trichome cell walls requires the function of the mediator complex subunit Med25.

    PubMed

    Fornero, Christy; Suo, Bangxia; Zahde, Mais; Juveland, Katelyn; Kirik, Viktor

    2017-11-01

    Glassy Hair 1 (GLH1) gene that promotes papillae formation on trichome cell walls was identified as a subunit of the transcriptional mediator complex MED25. The MED25 gene is shown to be expressed in trichomes. The expression of the trichome development marker genes GLABRA2 (GL2) and Ethylene Receptor2 (ETR2) is not affected in the glh1 mutant. Presented data suggest that Arabidopsis MED25 mediator component is likely involved in the transcription of genes promoting papillae deposition in trichomes. The plant cell wall plays an important role in communication, defense, organization and support. The importance of each of these functions varies by cell type. Specialized cells, such as Arabidopsis trichomes, exhibit distinct cell wall characteristics including papillae. To better understand the molecular processes important for papillae deposition on the cell wall surface, we identified the GLASSY HAIR 1 (GLH1) gene, which is necessary for papillae formation. We found that a splice-site mutation in the component of the transcriptional mediator complex MED25 gene is responsible for the near papillae-less phenotype of the glh1 mutant. The MED25 gene is expressed in trichomes. Reporters for trichome developmental marker genes GLABRA2 (GL2) and Ethylene Receptor2 (ETR2) were not affected in the glh1 mutant. Collectively, the presented results show that MED25 is necessary for papillae formation on the cell wall surface of leaf trichomes and suggest that the Arabidopsis MED25 mediator component is likely involved in the transcription of a subset of genes that promote papillae deposition in trichomes.

  19. Endosomal receptor kinetics determine the stability of intracellular growth factor signalling complexes

    PubMed Central

    Tzafriri, A. Rami; Edelman, Elazer R.

    2006-01-01

    There is an emerging paradigm that growth factor signalling continues in the endosome and that cell response to a growth factor is defined by the integration of cell surface and endosomal events. As activated receptors in the endosome are exposed to a different set of binding partners, they probably elicit differential signals compared with when they are at the cell surface. As such, complete appreciation of growth factor signalling requires understanding of growth factor–receptor binding and trafficking kinetics both at the cell surface and in endosomes. Growth factor binding to surface receptors is well characterized, and endosomal binding is assumed to follow surface kinetics if one accounts for changes in pH. Yet, specific binding kinetics within the endosome has not been examined in detail. To parse the factors governing the binding state of endosomal receptors we analysed a whole-cell mathematical model of epidermal growth factor receptor trafficking and binding. We discovered that the stability of growth factor–receptor complexes within endosomes is governed by three primary independent factors: the endosomal dissociation constant, total endosomal volume and the number of endosomal receptors. These factors were combined into a single dimensionless parameter that determines the endosomal binding state of the growth factor–receptor complex and can distinguish different growth factors from each other and different cell states. Our findings indicate that growth factor binding within endosomal compartments cannot be appreciated solely on the basis of the pH-dependence of the dissociation constant and that the concentration of receptors in the endosomal compartment must also be considered. PMID:17117924

  20. Synergistic Effects of Vascular Endothelial Growth Factor on Bone Morphogenetic Proteins Induced Bone Formation In Vivo: Influencing Factors and Future Research Directions

    PubMed Central

    Li, Bo; Wang, Hai; Qiu, Guixing; Su, Xinlin

    2016-01-01

    Vascular endothelial growth factor (VEGF) and bone morphogenetic proteins (BMPs), as key mediators in angiogenesis and osteogenesis, are used in a combined delivery manner as a novel strategy in bone tissue engineering. VEGF has the potential to enhance BMPs induced bone formation. Both gene delivery and material-based delivery systems were incorporated in previous studies to investigate the synergistic effects of VEGF and BMPs. However, their results were controversial due to variation of methods incorporated in different studies. Factors influencing the synergistic effects of VEGF on BMPs induced bone formation were identified and analyzed in this review to reduce confusion on this issue. The potential mechanisms and directions of future studies were also proposed here. Further investigating mechanisms of the synergistic effects and optimizing these influencing factors will help to generate more effective bone regeneration. PMID:28070506

  1. Molybdenum Hydride and Dihydride Complexes Bearing Diphosphine Ligands with a Pendant Amine: Formation of Complexes With Bound Amines

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Shaoguang; Bullock, R. Morris

    2015-07-06

    CpMo(CO)(PNP)H complexes (PNP = (R2PCH2)2NMe, R = Et or Ph) were synthesized by displacement of two CO ligands of CpMo(CO)3H by the PNP ligand; these complexes were characterized by IR and variable temperature 1H and 31P NMR spectroscopy. CpMo(CO)(PNP)H complexes are formed as mixture of cis and trans-isomers. Both cis-CpMo(CO)(PEtNMePEt)H and trans-CpMo(CO)(PPhNMePPh)H were analyzed by single crystal X-ray diffraction. Electrochemical oxidation of CpMo(CO)(PEtNMePEt)H and CpMo(CO)(PPhNMePPh)H in CH3CN are both irreversible at slow scan rates and quasi-reversible at higher scan rates, with E1/2 = -0.36 V (vs. Cp2Fe+/0) for CpMo(CO)(PEtNMePEt)H and E1/2 = -0.18 V for CpMo(CO)(PPhNMePPh)H. Hydride abstraction from CpMo(CO)(PNP)Hmore » with [Ph3C]+[A]- (A = B(C6F5)4 or BArF4; [ArF = 3,5-bis(trifluoromethyl)phenyl]) afforded “tuck-in” [CpMo(CO)(κ3-PNP)]+ complexes that feature the amine bound to the metal. Displacement of the κ3 Mo-N bond by CD3CN gives [CpMo(CO)(PNP)(CD3CN)]+. The kinetics of this reaction were studied by NMR spectroscopy, providing the activation parameters ΔH‡ = 22.1 kcal/mol, ΔS‡ = 1.89 cal/(mol·K), Ea = 22.7 kcal/mol. Protonation of CpMo(CO)(PEtNMePEt)H affords [CpMo(CO)(κ2-PEtNMePEt)(H)2]+ as a Mo dihydride complex, which loses H2 to generate [CpMo(CO)(κ3-PEtNMePEt)]+ at room temperature. CpMo(CO)(dppp)H (dppp = 1,2-bis(diphenylphosphino)propane) was studied as a Mo diphosphine analogue without a pendant amine, and the product of protonation of this complex gives [CpMo(CO)(dppp)(H)2]+. Our results show that the pendant amine has a strong driving force to form stable “tuck-in” [CpMo(CO)(κ3-PNP)]+ complexes, and also promotes hydrogen elimination from [CpMo(CO)(PNP)(H)2]+ complexes by formation of Mo-N dative bond. We thank the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences for support. Pacific Northwest National Laboratory is operated

  2. Chansporter complexes in cell signaling.

    PubMed

    Abbott, Geoffrey W

    2017-09-01

    Ion channels facilitate diffusion of ions across cell membranes for such diverse purposes as neuronal signaling, muscular contraction, and fluid homeostasis. Solute transporters often utilize ionic gradients to move aqueous solutes up their concentration gradient, also fulfilling a wide variety of tasks. Recently, an increasing number of ion channel-transporter ('chansporter') complexes have been discovered. Chansporter complex formation may overcome what could otherwise be considerable spatial barriers to rapid signal integration and feedback between channels and transporters, the ions and other substrates they transport, and environmental factors to which they must respond. Here, current knowledge in this field is summarized, covering both heterologous expression structure/function findings and potential mechanisms by which chansporter complexes fulfill contrasting roles in cell signaling in vivo. © 2017 Federation of European Biochemical Societies.

  3. Cyclin A and the retinoblastoma gene product complex with a common transcription factor.

    PubMed

    Bandara, L R; Adamczewski, J P; Hunt, T; La Thangue, N B

    1991-07-18

    The retinoblastoma gene (Rb) product is a negative regulator of cellular proliferation, an effect that could be mediated in part at the transcriptional level through its ability to complex with the sequence-specific transcription factor DRTF1. This interaction is modulated by adenovirus E1a, which sequesters the Rb protein and several other cellular proteins, including cyclin A, a molecule that undergoes cyclical accumulation and destruction during each cell cycle and which is required for cell cycle progression. Cyclin A, which also complexes with DRTF1, facilitates the efficient assembly of the Rb protein into the complex. This suggests a role for cyclin A in regulating transcription and defines a transcription factor through which molecules that regulate the cell cycle in a negative fashion, such as Rb, and in a positive fashion, such as cyclin A, interact. Mutant loss-of-function Rb alleles, which occur in a variety of tumour cells, also fail to complex with E1a and large T antigen. Here we report on a naturally occurring loss-of-function Rb allele encoding a protein that fails to complex with DRTF1. This might explain how mutation in the Rb gene prevents negative growth control.

  4. Glutathione Complex Formation With Mercury(Ii) in Aqueous Solution at Physiological Ph

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mah, V.; Jalilehvand, F.; /SLAC

    2012-08-23

    not consistent with the formation of dimeric Hg(II)-GSH complexes proposed in a recent EXAFS study.« less

  5. Thermodynamic study of complex formation between Ce3+ and cryptand 222 in some binary mixed nonaqueous solvents

    NASA Astrophysics Data System (ADS)

    Rounaghi, G. H.; Dolatshahi, S.; Tarahomi, S.

    2014-12-01

    The stoichiometry, stability and the thermodynamic parameters of complex formation between cerium(III) cation and cryptand 222 (4,7,13,16,21,24-hexaoxa-1,10-diazabycyclo[8.8.8]-hexacosane) were studied by conductometric titration method in some binary solvent mixtures of dimethylformamide (DMF), 1,2-dichloroethane (DCE), ethyl acetate (EtOAc) and methyl acetate (MeOAc) with methanol (MeOH), at 288, 298, 308, and 318 K. A model based on 1: 1 stoichiometry has been used to analyze the conductivity data. The data have been fitted according to a non-linear least-squares analysis that provide the stability constant, K f, for the cation-ligand inclusion complex. The results revealed that the stability order of [Ce(cryptand 222)]3+ complex changes with the nature and composition of the solvent system. A non-linear relationship was observed between the stability constant (log K f) of [Ce(cryptand 222)]3+ complex versus the composition of the binary mixed solvent. Standard thermodynamic values were obtained from temperature dependence of the stability constant of the complex, show that the studied complexation process is mainly entropy governed and are influenced by the nature and composition of the binary mixed solvent solutions.

  6. TIMMDC1/C3orf1 functions as a membrane-embedded mitochondrial complex I assembly factor through association with the MCIA complex.

    PubMed

    Guarani, Virginia; Paulo, Joao; Zhai, Bo; Huttlin, Edward L; Gygi, Steven P; Harper, J Wade

    2014-03-01

    Complex I (CI) of the electron transport chain, a large membrane-embedded NADH dehydrogenase, couples electron transfer to the release of protons into the mitochondrial inner membrane space to promote ATP production through ATP synthase. In addition to being a central conduit for ATP production, CI activity has been linked to neurodegenerative disorders, including Parkinson's disease. CI is built in a stepwise fashion through the actions of several assembly factors. We employed interaction proteomics to interrogate the molecular associations of 15 core subunits and assembly factors previously linked to human CI deficiency, resulting in a network of 101 proteins and 335 interactions (edges). TIMMDC1, a predicted 4-pass membrane protein, reciprocally associated with multiple members of the MCIA CI assembly factor complex and core CI subunits and was localized in the mitochondrial inner membrane, and its depletion resulted in reduced CI activity and cellular respiration. Quantitative proteomics demonstrated a role for TIMMDC1 in assembly of membrane-embedded and soluble arms of the complex. This study defines a new membrane-embedded CI assembly factor and provides a resource for further analysis of CI biology.

  7. Molecular stress-inducing compounds increase osteoclast formation in a heat shock factor 1 protein-dependent manner.

    PubMed

    Chai, Ryan C; Kouspou, Michelle M; Lang, Benjamin J; Nguyen, Chau H; van der Kraan, A Gabrielle J; Vieusseux, Jessica L; Lim, Reece C; Gillespie, Matthew T; Benjamin, Ivor J; Quinn, Julian M W; Price, John T

    2014-05-09

    Many anticancer therapeutic agents cause bone loss, which increases the risk of fractures that severely reduce quality of life. Thus, in drug development, it is critical to identify and understand such effects. Anticancer therapeutic and HSP90 inhibitor 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) causes bone loss by increasing osteoclast formation, but the mechanism underlying this is not understood. 17-AAG activates heat shock factor 1 (Hsf1), the master transcriptional regulator of heat shock/cell stress responses, which may be involved in this negative action of 17-AAG upon bone. Using mouse bone marrow and RAW264.7 osteoclast differentiation models we found that HSP90 inhibitors that induced a heat shock response also enhanced osteoclast formation, whereas HSP90 inhibitors that did not (including coumermycin A1 and novobiocin) did not affect osteoclast formation. Pharmacological inhibition or shRNAmir knockdown of Hsf1 in RAW264.7 cells as well as the use of Hsf1 null mouse bone marrow cells demonstrated that 17-AAG-enhanced osteoclast formation was Hsf1-dependent. Moreover, ectopic overexpression of Hsf1 enhanced 17-AAG effects upon osteoclast formation. Consistent with these findings, protein levels of the essential osteoclast transcription factor microphthalmia-associated transcription factor were increased by 17-AAG in an Hsf1-dependent manner. In addition to HSP90 inhibitors, we also identified that other agents that induced cellular stress, such as ethanol, doxorubicin, and methotrexate, also directly increased osteoclast formation, potentially in an Hsf1-dependent manner. These results, therefore, indicate that cellular stress can enhance osteoclast differentiation via Hsf1-dependent mechanisms and may significantly contribute to pathological and therapeutic related bone loss.

  8. Starch-lipid inclusion complexes for aerogel formation

    USDA-ARS?s Scientific Manuscript database

    Recently we reported that aqueous slurries of starch can be excess steam jet-cooked and blended with aqueous solutions of fatty acid salts to produce inclusion complexes between amylose and the fatty acid salt. These complexes can be simply prepared on large scale using commercially available steam ...

  9. Complex Interdependence Regulates Heterotypic Transcription Factor Distribution and Coordinates Cardiogenesis.

    PubMed

    Luna-Zurita, Luis; Stirnimann, Christian U; Glatt, Sebastian; Kaynak, Bogac L; Thomas, Sean; Baudin, Florence; Samee, Md Abul Hassan; He, Daniel; Small, Eric M; Mileikovsky, Maria; Nagy, Andras; Holloway, Alisha K; Pollard, Katherine S; Müller, Christoph W; Bruneau, Benoit G

    2016-02-25

    Transcription factors (TFs) are thought to function with partners to achieve specificity and precise quantitative outputs. In the developing heart, heterotypic TF interactions, such as between the T-box TF TBX5 and the homeodomain TF NKX2-5, have been proposed as a mechanism for human congenital heart defects. We report extensive and complex interdependent genomic occupancy of TBX5, NKX2-5, and the zinc finger TF GATA4 coordinately controlling cardiac gene expression, differentiation, and morphogenesis. Interdependent binding serves not only to co-regulate gene expression but also to prevent TFs from distributing to ectopic loci and activate lineage-inappropriate genes. We define preferential motif arrangements for TBX5 and NKX2-5 cooperative binding sites, supported at the atomic level by their co-crystal structure bound to DNA, revealing a direct interaction between the two factors and induced DNA bending. Complex interdependent binding mechanisms reveal tightly regulated TF genomic distribution and define a combinatorial logic for heterotypic TF regulation of differentiation. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Solo, a RhoA-targeting guanine nucleotide exchange factor, is critical for hemidesmosome formation and acinar development in epithelial cells.

    PubMed

    Fujiwara, Sachiko; Matsui, Tsubasa S; Ohashi, Kazumasa; Deguchi, Shinji; Mizuno, Kensaku

    2018-01-01

    Cell-substrate adhesions are essential for various physiological processes, including embryonic development and maintenance of organ functions. Hemidesmosomes (HDs) are multiprotein complexes that attach epithelial cells to the basement membrane. Formation and remodeling of HDs are dependent on the surrounding mechanical environment; however, the upstream signaling mechanisms are not well understood. We recently reported that Solo (also known as ARHGEF40), a guanine nucleotide exchange factor targeting RhoA, binds to keratin8/18 (K8/K18) intermediate filaments, and that their interaction is important for force-induced actin and keratin cytoskeletal reorganization. In this study, we show that Solo co-precipitates with an HD protein, β4-integrin. Co-precipitation assays revealed that the central region (amino acids 330-1057) of Solo binds to the C-terminal region (1451-1752) of β4-integrin. Knockdown of Solo significantly suppressed HD formation in MCF10A mammary epithelial cells. Similarly, knockdown of K18 or treatment with Y-27632, a specific inhibitor of Rho-associated kinase (ROCK), suppressed HD formation. As Solo knockdown or Y-27632 treatment is known to disorganize K8/K18 filaments, these results suggest that Solo is involved in HD formation by regulating K8/K18 filament organization via the RhoA-ROCK signaling pathway. We also showed that knockdown of Solo impairs acinar formation in MCF10A cells cultured in 3D Matrigel. In addition, Solo accumulated at the site of traction force generation in 2D-cultured MCF10A cells. Taken together, these results suggest that Solo plays a crucial role in HD formation and acinar development in epithelial cells by regulating mechanical force-induced RhoA activation and keratin filament organization.

  11. Solo, a RhoA-targeting guanine nucleotide exchange factor, is critical for hemidesmosome formation and acinar development in epithelial cells

    PubMed Central

    Matsui, Tsubasa S.; Ohashi, Kazumasa; Deguchi, Shinji; Mizuno, Kensaku

    2018-01-01

    Cell-substrate adhesions are essential for various physiological processes, including embryonic development and maintenance of organ functions. Hemidesmosomes (HDs) are multiprotein complexes that attach epithelial cells to the basement membrane. Formation and remodeling of HDs are dependent on the surrounding mechanical environment; however, the upstream signaling mechanisms are not well understood. We recently reported that Solo (also known as ARHGEF40), a guanine nucleotide exchange factor targeting RhoA, binds to keratin8/18 (K8/K18) intermediate filaments, and that their interaction is important for force-induced actin and keratin cytoskeletal reorganization. In this study, we show that Solo co-precipitates with an HD protein, β4-integrin. Co-precipitation assays revealed that the central region (amino acids 330–1057) of Solo binds to the C-terminal region (1451–1752) of β4-integrin. Knockdown of Solo significantly suppressed HD formation in MCF10A mammary epithelial cells. Similarly, knockdown of K18 or treatment with Y-27632, a specific inhibitor of Rho-associated kinase (ROCK), suppressed HD formation. As Solo knockdown or Y-27632 treatment is known to disorganize K8/K18 filaments, these results suggest that Solo is involved in HD formation by regulating K8/K18 filament organization via the RhoA-ROCK signaling pathway. We also showed that knockdown of Solo impairs acinar formation in MCF10A cells cultured in 3D Matrigel. In addition, Solo accumulated at the site of traction force generation in 2D-cultured MCF10A cells. Taken together, these results suggest that Solo plays a crucial role in HD formation and acinar development in epithelial cells by regulating mechanical force-induced RhoA activation and keratin filament organization. PMID:29672603

  12. DOTA analogues with a phosphinate-iminodiacetate pendant arm: modification of the complex formation rate with a strongly chelating pendant.

    PubMed

    Procházková, Soňa; Kubíček, Vojtěch; Böhmová, Zuzana; Holá, Kateřina; Kotek, Jan; Hermann, Petr

    2017-08-08

    The new ligand H 6 do3aP ida combines the macrocyclic DOTA-like cavity and the open-chain iminodiacetate group connected through a coordinating phosphinate spacer. Its acid-base and coordination properties in solution were studied by potentiometry. Thermodynamic coordination characteristics of both chelating units are similar to those reported for H 4 dota and iminodiacetic acid themselves, respectively, so, macrocyclic and iminodiacetate units behave independently. The formation kinetics of the Ce(iii)-H 6 do3aP ida complex was studied by UV-Vis spectrophotometry. Various out-of-cage intermediates were identified with 1 : 1, 1 : 2 and 2 : 1 ligand-to-metal ratios. The presence of the strongly coordinating iminodiacetate group significantly slows down the metal ion transfer into the macrocyclic cavity and, so, the formation of the in-cage complex is two orders of magnitude slower than that reported for the Ce(iii)-H 4 dota system. The kinetic inertness of the [Ce(do3aP ida )] 3- complex towards acid-assisted dissociation is comparable to that of the [Ce(dota)] - complex. The coordination modes of the ligand are demonstrated in the solid-state structure of [Cu 4 (do3aP ida )(OH)(H 2 O) 4 ]Cl·7.5H 2 O.

  13. Considerable fluorescence enhancement upon supramolecular complex formation between berberine and p-sulfonated calixarenes

    NASA Astrophysics Data System (ADS)

    Megyesi, Mónika; Biczók, László

    2006-06-01

    Remarkably strong binding of berberine to 4-sulfonatocalix[8]arene was found in aqueous solution, which led to fluorescence quantum yield increase of a factor about 40 at pH 2. The hypsochromic shift of the fluorescence maximum implied that berberine sensed less polar microenvironment when confined to SCX8. The stability of the supramolecular complex significantly diminished when sulfocalixarenes of smaller ring size served as host compounds but the pH affected the association strength to a much lesser extent. All berberine complexes proved to be barely fluorescent at pH 12.2 because of excited state quenching by the hosts via electron transfer.

  14. Photosynthesis. Electronic structure of the oxygen-evolving complex in photosystem II prior to O-O bond formation.

    PubMed

    Cox, Nicholas; Retegan, Marius; Neese, Frank; Pantazis, Dimitrios A; Boussac, Alain; Lubitz, Wolfgang

    2014-08-15

    The photosynthetic protein complex photosystem II oxidizes water to molecular oxygen at an embedded tetramanganese-calcium cluster. Resolving the geometric and electronic structure of this cluster in its highest metastable catalytic state (designated S3) is a prerequisite for understanding the mechanism of O-O bond formation. Here, multifrequency, multidimensional magnetic resonance spectroscopy reveals that all four manganese ions of the catalyst are structurally and electronically similar immediately before the final oxygen evolution step; they all exhibit a 4+ formal oxidation state and octahedral local geometry. Only one structural model derived from quantum chemical modeling is consistent with all magnetic resonance data; its formation requires the binding of an additional water molecule. O-O bond formation would then proceed by the coupling of two proximal manganese-bound oxygens in the transition state of the cofactor. Copyright © 2014, American Association for the Advancement of Science.

  15. Kinetic factors determining conducting filament formation in solid polymer electrolyte based planar devices

    NASA Astrophysics Data System (ADS)

    Krishnan, Karthik; Aono, Masakazu; Tsuruoka, Tohru

    2016-07-01

    Resistive switching characteristics and conducting filament formation dynamics in solid polymer electrolyte (SPE) based planar-type atomic switches, with opposing active Ag and inert Pt electrodes, have been investigated by optimizing the device configuration and experimental parameters such as the gap distance between the electrodes, the salt inclusion in the polymer matrix, and the compliance current applied in current-voltage measurements. The high ionic conductivities of SPE enabled us to make scanning electron microscopy observations of the filament formation processes in the sub-micrometer to micrometer ranges. It was found that switching behaviour and filament growth morphology depend strongly on several kinetic factors, such as the redox reaction rate at the electrode-polymer interfaces, ion mobility in the polymer matrix, electric field strength, and the reduction sites for precipitation. Different filament formations, resulting from unidirectional and dendritic growth behaviours, can be controlled by tuning specified parameters, which in turn improves the stability and performance of SPE-based devices.Resistive switching characteristics and conducting filament formation dynamics in solid polymer electrolyte (SPE) based planar-type atomic switches, with opposing active Ag and inert Pt electrodes, have been investigated by optimizing the device configuration and experimental parameters such as the gap distance between the electrodes, the salt inclusion in the polymer matrix, and the compliance current applied in current-voltage measurements. The high ionic conductivities of SPE enabled us to make scanning electron microscopy observations of the filament formation processes in the sub-micrometer to micrometer ranges. It was found that switching behaviour and filament growth morphology depend strongly on several kinetic factors, such as the redox reaction rate at the electrode-polymer interfaces, ion mobility in the polymer matrix, electric field strength

  16. Ab initio study on the formation of triiodide CT complex from the reaction of iodine with 2,3-diaminopyridine.

    PubMed

    Al-Hashimi, Nessreen A; Hussein, Yasser H A

    2010-01-01

    The charge transfer (CT) interaction between iodine and 2,3-diaminopyridine (DAPY) has been thoroughly investigated via theoretical calculations. A Hartree-Fock, 3-21G level of theory was used to optimize and calculate the Mullican charge distribution scheme as well as the vibrational frequencies of DAPY alone and both its CT complexes with one and two iodine molecules. A very good agreement was found between experiment and theory. New illustrations were concluded with a deep analysis and description for the vibrational frequencies of the formed CT complexes. The two-step CT complex formation mechanism published earlier was supported. Copyright 2009 Elsevier B.V. All rights reserved.

  17. Transcription factors define the neuroanatomical organization of the medullary reticular formation

    PubMed Central

    Gray, Paul A.

    2013-01-01

    The medullary reticular formation contains large populations of inadequately described, excitatory interneurons that have been implicated in multiple homeostatic behaviors including breathing, viserosensory processing, vascular tone, and pain. Many hindbrain nuclei show a highly stereotyped pattern of localization across vertebrates suggesting a strong underlying genetic organization. Whether this is true for neurons within the reticular regions of hindbrain is unknown. Hindbrain neurons are derived from distinct developmental progenitor domains each of which expresses distinct patterns of transcription factors (TFs). These neuronal populations have distinct characteristics such as transmitter identity, migration, and connectivity suggesting developmentally expressed TFs might identify unique subpopulations of neurons within the reticular formation. A fate-mapping strategy using perinatal expression of reporter genes within Atoh1, Dbx1, Lmx1b, and Ptf1a transgenic mice coupled with immunohistochemistry (IHC) and in situ hybridization (ISH) were used to address the developmental organization of a large subset of reticular formation glutamatergic neurons. All hindbrain lineages have relatively large populations that extend the entire length of the hindbrain. Importantly, the location of neurons within each lineage was highly constrained. Lmx1b- and Dbx1- derived populations were both present in partially overlapping stripes within the reticular formation extending from dorsal to ventral brain. Within each lineage, distinct patterns of gene expression and organization were localized to specific hindbrain regions. Rostro-caudally sub-populations differ sequentially corresponding to proposed pseudo-rhombomereic boundaries. Dorsal-ventrally, sub-populations correspond to specific migratory positions. Together these data suggests the reticular formation is organized by a highly stereotyped developmental logic. PMID:23717265

  18. Transcription factors define the neuroanatomical organization of the medullary reticular formation.

    PubMed

    Gray, Paul A

    2013-01-01

    The medullary reticular formation contains large populations of inadequately described, excitatory interneurons that have been implicated in multiple homeostatic behaviors including breathing, viserosensory processing, vascular tone, and pain. Many hindbrain nuclei show a highly stereotyped pattern of localization across vertebrates suggesting a strong underlying genetic organization. Whether this is true for neurons within the reticular regions of hindbrain is unknown. Hindbrain neurons are derived from distinct developmental progenitor domains each of which expresses distinct patterns of transcription factors (TFs). These neuronal populations have distinct characteristics such as transmitter identity, migration, and connectivity suggesting developmentally expressed TFs might identify unique subpopulations of neurons within the reticular formation. A fate-mapping strategy using perinatal expression of reporter genes within Atoh1, Dbx1, Lmx1b, and Ptf1a transgenic mice coupled with immunohistochemistry (IHC) and in situ hybridization (ISH) were used to address the developmental organization of a large subset of reticular formation glutamatergic neurons. All hindbrain lineages have relatively large populations that extend the entire length of the hindbrain. Importantly, the location of neurons within each lineage was highly constrained. Lmx1b- and Dbx1- derived populations were both present in partially overlapping stripes within the reticular formation extending from dorsal to ventral brain. Within each lineage, distinct patterns of gene expression and organization were localized to specific hindbrain regions. Rostro-caudally sub-populations differ sequentially corresponding to proposed pseudo-rhombomereic boundaries. Dorsal-ventrally, sub-populations correspond to specific migratory positions. Together these data suggests the reticular formation is organized by a highly stereotyped developmental logic.

  19. Cluster formation by allelomimesis in real-world complex adaptive systems

    NASA Astrophysics Data System (ADS)

    Juanico, Dranreb Earl; Monterola, Christopher; Saloma, Caesar

    2005-04-01

    Animal and human clusters are complex adaptive systems and many organize in cluster sizes s that obey the frequency distribution D(s)∝s-τ . The exponent τ describes the relative abundance of the cluster sizes in a given system. Data analyses reveal that real-world clusters exhibit a broad spectrum of τ values, 0.7 (tuna fish schools) ⩽τ⩽4.61 (T4 bacteriophage gene family sizes). Allelomimesis is proposed as an underlying mechanism for adaptation that explains the observed broad τ spectrum. Allelomimesis is the tendency of an individual to imitate the actions of others and two cluster systems have different τ values when their component agents display unequal degrees of allelomimetic tendencies. Cluster formation by allelomimesis is shown to be of three general types: namely, blind copying, information-use copying, and noncopying. Allelomimetic adaptation also reveals that the most stable cluster size is formed by three strongly allelomimetic individuals. Our finding is consistent with available field data taken from killer whales and marmots.

  20. Adhesion and formation of microbial biofilms in complex microfluidic devices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, Aloke; Karig, David K; Neethirajan, Suresh

    2012-01-01

    Shewanella oneidensis is a metal reducing bacterium, which is of interest for bioremediation and clean energy applications. S. oneidensis biofilms play a critical role in several situations such as in microbial energy harvesting devices. Here, we use a microfluidic device to quantify the effects of hydrodynamics on the biofilm morphology of S. oneidensis. For different rates of fluid flow through a complex microfluidic device, we studied the spatiotemporal dynamics of biofilms, and we quantified several morphological features such as spatial distribution, cluster formation and surface coverage. We found that hydrodynamics resulted in significant differences in biofilm dynamics. The baffles inmore » the device created regions of low and high flow in the same device. At higher flow rates, a nonuniform biofilm develops, due to unequal advection in different regions of the microchannel. However, at lower flow rates, a more uniform biofilm evolved. This depicts competition between adhesion events, growth and fluid advection. Atomic force microscopy (AFM) revealed that higher production of extra-cellular polymeric substances (EPS) occurred at higher flow velocities.« less

  1. Quantitative imaging reveals real-time Pou5f3–Nanog complexes driving dorsoventral mesendoderm patterning in zebrafish

    PubMed Central

    Perez-Camps, Mireia; Tian, Jing; Chng, Serene C; Sem, Kai Pin; Sudhaharan, Thankiah; Teh, Cathleen; Wachsmuth, Malte; Korzh, Vladimir; Ahmed, Sohail; Reversade, Bruno

    2016-01-01

    Formation of the three embryonic germ layers is a fundamental developmental process that initiates differentiation. How the zebrafish pluripotency factor Pou5f3 (homologous to mammalian Oct4) drives lineage commitment is unclear. Here, we introduce fluorescence lifetime imaging microscopy and fluorescence correlation spectroscopy to assess the formation of Pou5f3 complexes with other transcription factors in real-time in gastrulating zebrafish embryos. We show, at single-cell resolution in vivo, that Pou5f3 complexes with Nanog to pattern mesendoderm differentiation at the blastula stage. Later, during gastrulation, Sox32 restricts Pou5f3–Nanog complexes to the ventrolateral mesendoderm by binding Pou5f3 or Nanog in prospective dorsal endoderm. In the ventrolateral endoderm, the Elabela / Aplnr pathway limits Sox32 levels, allowing the formation of Pou5f3–Nanog complexes and the activation of downstream BMP signaling. This quantitative model shows that a balance in the spatiotemporal distribution of Pou5f3–Nanog complexes, modulated by Sox32, regulates mesendoderm specification along the dorsoventral axis. DOI: http://dx.doi.org/10.7554/eLife.11475.001 PMID:27684073

  2. Investigating the Effect of Complexity Factors in Gas Law Problems

    ERIC Educational Resources Information Center

    Schuttlefield, Jennifer D.; Kirk, John; Pienta, Norbert J.; Tang, Hui

    2012-01-01

    Undergraduate students were asked to complete gas law questions using a Web-based tool as a first step in our understanding of the role of cognitive load in chemistry word questions and in helping us assess student problem-solving. Each question contained five different complexity factors, which were randomly assigned by the tool so that a…

  3. Selective CO2 conversion to formate conjugated with H2O oxidation utilizing semiconductor/complex hybrid photocatalysts.

    PubMed

    Sato, Shunsuke; Arai, Takeo; Morikawa, Takeshi; Uemura, Keiko; Suzuki, Tomiko M; Tanaka, Hiromitsu; Kajino, Tsutomu

    2011-10-05

    Photoelectrochemical reduction of CO(2) to HCOO(-) (formate) over p-type InP/Ru complex polymer hybrid photocatalyst was highly enhanced by introducing an anchoring complex into the polymer. By functionally combining the hybrid photocatalyst with TiO(2) for water oxidation, selective photoreduction of CO(2) to HCOO(-) was achieved in aqueous media, in which H(2)O was used as both an electron donor and a proton source. The so-called Z-scheme (or two-step photoexcitation) system operated with no external electrical bias. The selectivity for HCOO(-) production was >70%, and the conversion efficiency of solar energy to chemical energy was 0.03-0.04%.

  4. Characterization of the effect of serum and chelating agents on Staphylococcus aureus biofilm formation; chelating agents augment biofilm formation through clumping factor B

    NASA Astrophysics Data System (ADS)

    Abraham, Nabil Mathew

    Staphylococcus aureus is the causative agent of a diverse array of acute and chronic infections, and some these infections, including infective endocarditis, joint infections, and medical device-associated bloodstream infections, depend upon its capacity to form tenacious biofilms on surfaces. Inserted medical devices such as intravenous catheters, pacemakers, and artificial heart valves save lives, but unfortunately, they can also serve as a substrate on which S. aureus can form a biofilm, attributing S. aureus as a leading cause of medical device-related infections. The major aim of this work was take compounds to which S. aureus would be exposed during infection and to investigate their effects on its capacity to form a biofilm. More specifically, the project investigated the effects of serum, and thereafter of catheter lock solutions on biofilm formation by S. aureus. Pre-coating polystyrene with serum is frequently used as a method to augment biofilm formation. The effect of pre-coating with serum is due to the deposition of extracellular matrix components onto the polystyrene, which are then recognized by MSCRAMMs. We therefore hypothesized that the major component of blood, serum, would induce biofilm formation. Surprisingly, serum actually inhibited biofilm formation. The inhibitory activity was due to a small molecular weight, heat-stable, non-proteinaceous component/s of serum. Serum-mediated inhibition of biofilm formation may represent a previously uncharacterized aspect of host innate immunity that targets the expression of a key bacterial virulence factor: the ability to establish a resistant biofilm. Metal ion chelators like sodium citrate are frequently chosen to lock intravenous catheters because they are regarded as potent inhibitors of bacterial biofilm formation and viability. We found that, while chelating compounds abolished biofilm formation in most strains of S. aureus, they actually augmented the phenotype in a subset of strains. We

  5. Complex Pattern Formation from Current-Driven Dynamics of Single-Layer Epitaxial Islands on Crystalline Conducting Substrates

    NASA Astrophysics Data System (ADS)

    Kumar, Ashish; Dasgupta, Dwaipayan; Maroudas, Dimitrios

    We report a systematic study of complex pattern formation resulting from the driven dynamics of single-layer homoepitaxial islands on face-centered cubic (FCC) crystalline conducting substrate surfaces under the action of an externally applied electric field. The analysis is based on an experimentally validated nonlinear model of mass transport via island edge atomic diffusion, which also accounts for edge diffusional anisotropy. We analyze the morphological stability and simulate the field-driven evolution of rounded islands for an electric field oriented along the fast diffusion direction. For larger than critical island sizes on {110} and {100} FCC substrates, we show that multiple necking instabilities generate complex island patterns, including void-containing islands, mediated by sequences of breakup and coalescence events and distributed symmetrically with respect to the electric field direction. We analyze the dependence of the formed patterns on the original island size and on the duration of application of the external field. Starting from a single large rounded island, we characterize the evolution of the number of daughter islands and their average size and uniformity. The analysis reveals that the pattern formation kinetics follows a universal scaling relation. Division of Materials Sciences & Engineering, Office of Basic Energy Sciences, U.S. Department of Energy (Award No.: DE-FG02-07ER46407).

  6. Mutations in mitochondrial complex I assembly factor NDUFAF3 cause Leigh syndrome.

    PubMed

    Baertling, Fabian; Sánchez-Caballero, Laura; Timal, Sharita; van den Brand, Mariël Am; Ngu, Lock Hock; Distelmaier, Felix; Rodenburg, Richard Jt; Nijtmans, Leo Gj

    2017-03-01

    NDUFAF3 is an assembly factor of mitochondrial respiratory chain complex I. Variants in NDUFAF3 have been identified as a cause of severe multisystem mitochondrial disease. In a patient presenting with Leigh syndrome, which has hitherto not been described as a clinical feature of NDUFAF3 deficiency, we identified a novel homozygous variant and confirmed its pathogenicity in patient fibroblasts studies. Furthermore, we present an analysis of complex I assembly routes representative of each functional module and, thereby, link NDUFAF3 to a specific step in complex I assembly. Therefore, our report expands the phenotype of NDUFAF3 deficiency and further characterizes the role of NDUFAF3 in complex I biogenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

    PubMed Central

    Yang, Ruiyue; Huang, Zhongwei; Yu, Wei; Li, Gensheng; Ren, Wenxi; Zuo, Lihua; Tan, Xiaosi; Sepehrnoori, Kamy; Tian, Shouceng; Sheng, Mao

    2016-01-01

    A complex fracture network is generally generated during the hydraulic fracturing treatment in shale gas reservoirs. Numerous efforts have been made to model the flow behavior of such fracture networks. However, it is still challenging to predict the impacts of various gas transport mechanisms on well performance with arbitrary fracture geometry in a computationally efficient manner. We develop a robust and comprehensive model for real gas transport in shales with complex non-planar fracture network. Contributions of gas transport mechanisms and fracture complexity to well productivity and rate transient behavior are systematically analyzed. The major findings are: simple planar fracture can overestimate gas production than non-planar fracture due to less fracture interference. A “hump” that occurs in the transition period and formation linear flow with a slope less than 1/2 can infer the appearance of natural fractures. The sharpness of the “hump” can indicate the complexity and irregularity of the fracture networks. Gas flow mechanisms can extend the transition flow period. The gas desorption could make the “hump” more profound. The Knudsen diffusion and slippage effect play a dominant role in the later production time. Maximizing the fracture complexity through generating large connected networks is an effective way to increase shale gas production. PMID:27819349

  8. A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks.

    PubMed

    Yang, Ruiyue; Huang, Zhongwei; Yu, Wei; Li, Gensheng; Ren, Wenxi; Zuo, Lihua; Tan, Xiaosi; Sepehrnoori, Kamy; Tian, Shouceng; Sheng, Mao

    2016-11-07

    A complex fracture network is generally generated during the hydraulic fracturing treatment in shale gas reservoirs. Numerous efforts have been made to model the flow behavior of such fracture networks. However, it is still challenging to predict the impacts of various gas transport mechanisms on well performance with arbitrary fracture geometry in a computationally efficient manner. We develop a robust and comprehensive model for real gas transport in shales with complex non-planar fracture network. Contributions of gas transport mechanisms and fracture complexity to well productivity and rate transient behavior are systematically analyzed. The major findings are: simple planar fracture can overestimate gas production than non-planar fracture due to less fracture interference. A "hump" that occurs in the transition period and formation linear flow with a slope less than 1/2 can infer the appearance of natural fractures. The sharpness of the "hump" can indicate the complexity and irregularity of the fracture networks. Gas flow mechanisms can extend the transition flow period. The gas desorption could make the "hump" more profound. The Knudsen diffusion and slippage effect play a dominant role in the later production time. Maximizing the fracture complexity through generating large connected networks is an effective way to increase shale gas production.

  9. Structure Formation in Complex Plasma - Quantum Effects in Cryogenic Complex Plasmas

    DTIC Science & Technology

    2014-09-26

    pipe at the flange attached to the inner Dewar bottle. The temperature of the gas in the glass tube is controlled by the cryogenic liquid , liquid ...dust particles. The supersonic flow was possible to make in a complex plasma since dust acoustic wave is characterized by a sound speed of a few cm...through the illumination of laser light on dust particles. The supersonic flow was possible to make in a complex plasma since dust acoustic wave is

  10. Reactive Desorption and Radiative Association as Possible Drivers of Complex Molecule Formation in the Cold Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Vasyunin, A. I.; Herbst, Eric

    2013-05-01

    The recent discovery of terrestrial-type organic species such as methyl formate and dimethyl ether in the cold interstellar gas has proved that the formation of organic matter in the Galaxy begins at a much earlier stage of star formation than was previously thought. This discovery represents a challenge for astrochemical modelers. The abundances of these molecules cannot be explained by the previously developed "warm-up" scenario, in which organic molecules are formed via diffusive chemistry on surfaces of interstellar grains starting at 30 K, and then released to the gas at higher temperatures during later stages of star formation. In this article, we investigate an alternative scenario in which complex organic species are formed via a sequence of gas-phase reactions between precursor species formed on grain surfaces and then ejected into the gas via efficient reactive desorption, a process in which non-thermal desorption occurs as a result of conversion of the exothermicity of chemical reactions into the ejection of products from the surface. The proposed scenario leads to reasonable if somewhat mixed results at temperatures as low as 10 K and may be considered as a step toward the explanation of abundances of terrestrial-like organic species observed during the earliest stages of star formation.

  11. A stable transcription factor complex nucleated by oligomeric AML1–ETO controls leukaemogenesis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sun, Xiao-Jian; Wang, Zhanxin; Wang, Lan

    2013-06-30

    Transcription factors are frequently altered in leukaemia through chromosomal translocation, mutation or aberrant expression. AML1–ETO, a fusion protein generated by the t(8;21) translocation in acute myeloid leukaemia, is a transcription factor implicated in both gene repression and activation. AML1–ETO oligomerization, mediated by the NHR2 domain, is critical for leukaemogenesis, making it important to identify co-regulatory factors that ‘read’ the NHR2 oligomerization and contribute to leukaemogenesis. Here we show that, in human leukaemic cells, AML1–ETO resides in and functions through a stable AML1–ETO-containing transcription factor complex (AETFC) that contains several haematopoietic transcription (co)factors. These AETFC components stabilize the complex through multivalentmore » interactions, provide multiple DNA-binding domains for diverse target genes, co-localize genome wide, cooperatively regulate gene expression, and contribute to leukaemogenesis. Within the AETFC complex, AML1–ETO oligomerization is required for a specific interaction between the oligomerized NHR2 domain and a novel NHR2-binding (N2B) motif in E proteins. Crystallographic analysis of the NHR2–N2B complex reveals a unique interaction pattern in which an N2B peptide makes direct contact with side chains of two NHR2 domains as a dimer, providing a novel model of how dimeric/oligomeric transcription factors create a new protein-binding interface through dimerization/oligomerization. Intriguingly, disruption of this interaction by point mutations abrogates AML1–ETO-induced haematopoietic stem/progenitor cell self-renewal and leukaemogenesis. These results reveal new mechanisms of action of AML1–ETO, and provide a potential therapeutic target in t(8;21)-positive acute myeloid leukaemia.« less

  12. The statistical mechanics of complex signaling networks: nerve growth factor signaling

    NASA Astrophysics Data System (ADS)

    Brown, K. S.; Hill, C. C.; Calero, G. A.; Myers, C. R.; Lee, K. H.; Sethna, J. P.; Cerione, R. A.

    2004-10-01

    The inherent complexity of cellular signaling networks and their importance to a wide range of cellular functions necessitates the development of modeling methods that can be applied toward making predictions and highlighting the appropriate experiments to test our understanding of how these systems are designed and function. We use methods of statistical mechanics to extract useful predictions for complex cellular signaling networks. A key difficulty with signaling models is that, while significant effort is being made to experimentally measure the rate constants for individual steps in these networks, many of the parameters required to describe their behavior remain unknown or at best represent estimates. To establish the usefulness of our approach, we have applied our methods toward modeling the nerve growth factor (NGF)-induced differentiation of neuronal cells. In particular, we study the actions of NGF and mitogenic epidermal growth factor (EGF) in rat pheochromocytoma (PC12) cells. Through a network of intermediate signaling proteins, each of these growth factors stimulates extracellular regulated kinase (Erk) phosphorylation with distinct dynamical profiles. Using our modeling approach, we are able to predict the influence of specific signaling modules in determining the integrated cellular response to the two growth factors. Our methods also raise some interesting insights into the design and possible evolution of cellular systems, highlighting an inherent property of these systems that we call 'sloppiness.'

  13. Influence of RNA Strand Rigidity on Polyion Complex Formation with Block Catiomers.

    PubMed

    Hayashi, Kotaro; Chaya, Hiroyuki; Fukushima, Shigeto; Watanabe, Sumiyo; Takemoto, Hiroyasu; Osada, Kensuke; Nishiyama, Nobuhiro; Miyata, Kanjiro; Kataoka, Kazunori

    2016-03-01

    Polyion complexes (b-PICs) are prepared by mixing single- or double-stranded oligo RNA (aniomer) with poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL) (block catiomer) to clarify the effect of aniomer chain rigidity on association behaviors at varying concentrations. Here, a 21-mer single-stranded RNA (ssRNA) (persistence length: 1.0 nm) and a 21-mer double-stranded RNA (small interfering RNA, siRNA) (persistence length: 62 nm) are compared. Both oligo RNAs form a minimal charge-neutralized ionomer pair with a single PEG-PLL chain, termed unit b-PIC (uPIC), at low concentrations (<≈ 0.01 mg mL(-1)). Above the critical association concentration (≈ 0.01 mg mL(-1)), ssRNA b-PICs form secondary associates, PIC micelles, with sizes up to 30-70 nm, while no such multimolecular assembly is observed for siRNA b-PICs. The entropy gain associated with the formation of a segregated PIC phase in the multimolecular PIC micelles may not be large enough for rigid siRNA strands to compensate with appreciably high steric repulsion derived from PEG chains. Chain rigidity appears to be a critical parameter in polyion complex association. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. The influence of dissolved H2O content in supercritical carbon dioxide to the inclusion complexes formation of ketoprofen/β-cyclodextrin

    NASA Astrophysics Data System (ADS)

    Goenawan, Joshua; Trisanti, P. N.; Sumarno

    2015-12-01

    This work studies the relation between dissolved H2O content in supercritical carbon dioxide (SC-CO2) with the formation of ketoprofen (KP)/β-cyclodextrin(CD) inclusion complexes. The process involves a physical mixture of these two compounds into contact with the supercritical carbon dioxide which had been previously saturated with H2O over a certain duration. The pressure used for saturation process is 130 bar and saturation temperature was ranged between 30 °C to 50 °C. The inclusion process was achieved by keeping it for 2 hours at 160 bar and 200 bar with inclusion temperature of 50 °C. The results enable us to suggest explanations for the inclusion formation. The inclusion complexes can be formed by contacting the dissolved H2O in SC-CO2 to the physical mixture of KP and CD. An increase in the temperature of saturation process resulted in an increase of dissolved H2O content in the supercritical carbon dioxide. The increasing levels of this water soluble resulted an increase in the inclusion complexes that has been formed. The formation of inclusion complexes includes the water molecules enhancing the emptying of the CD cavities and being replaced by KP, towards a more stable energy state. The drug release used for analyzing the dissolution rate of the KP/CD complexes. The results vary from 79,85% to 99,98% after 45 minutes which is above the rate that has been assigned by Farmakope Indonesia at 70% dissolution rate for KP. The use of SC-CO2 offers a new methods for increasing the rate of dissolution of drugs that are hydrophobic such as KP. CO2 used as a supercritical fluid because of its relatively low cost, easily obtainable supercritical conditions, and lack of toxicity. The material samples were characterized by DSC and Spectrophotometer UV-vis technique.

  15. [Schizotypal Personality Questionnaire-Brief - Likert format: Factor structure analysis in general population in France].

    PubMed

    Ferchiou, A; Todorov, L; Lajnef, M; Baudin, G; Pignon, B; Richard, J-R; Leboyer, M; Szöke, A; Schürhoff, F

    2017-12-01

    The main objective of the study was to explore the factorial structure of the French version of the Schizotypal Personality Questionnaire-Brief (SPQ-B) in a Likert format, in a representative sample of the general population. In addition, differences in the dimensional scores of schizotypy according to gender and age were analyzed. As the study in the general population of schizotypal traits and its determinants has been recently proposed as a way toward the understanding of aetiology and pathophysiology of schizophrenia, consistent self-report tools are crucial to measure psychometric schizotypy. A shorter version of the widely used Schizotypal Personality Questionnaire (SPQ-Brief) has been extensively investigated in different countries, particularly in samples of students or clinical adolescents, and more recently, a few studies used a Likert-type scale format which allows partial endorsement of items and reduces the risk of defensive answers. A sample of 233 subjects representative of the adult population from an urban area near Paris (Créteil) was recruited using the "itinerary method". They completed the French version of the SPQ-B with a 5-point Likert-type response format (1=completely disagree; 5=completely agree). We examined the dimensional structure of the French version of the SPQ-B with a Principal Components Analysis (PCA) followed by a promax rotation. Factor selection was based on Eigenvalues over 1.0 (Kaiser's criterion), Cattell's Scree-plot test, and interpretability of the factors. Items with loadings greater than 0.4 were retained for each dimension. The internal consistency estimate of the dimensions was calculated with Cronbach's α. In order to study the influence of age and gender, we carried out a simple linear regression with the subscales as dependent variables. Our sample was composed of 131 women (mean age=52.5±18.2 years) and 102 men (mean age=53±18.1 years). SPQ-B Likert total scores ranged from 22 to 84 points (mean=43.6

  16. The MC160 Protein Expressed by the Dermatotropic Poxvirus Molluscum Contagiosum Virus Prevents Tumor Necrosis Factor Alpha-Induced NF-κB Activation via Inhibition of I Kappa Kinase Complex Formation

    PubMed Central

    Nichols, Daniel Brian; Shisler, Joanna L.

    2006-01-01

    The pluripotent cytokine tumor necrosis factor alpha (TNF-α) binds to its cognate TNF receptor I (TNF-RI) to stimulate inflammation via activation of the NF-κB transcription factor. To prevent the detrimental effects of TNF-α in keratinocytes infected with the molluscum contagiosum virus (MCV), this poxvirus is expected to produce proteins that block at least one step of the TNF-RI signal transduction pathway. One such product, the MC160 protein, is predicted to interfere with this cellular response because of its homology to other proteins that regulate TNF-RI-mediated signaling. We report here that expression of MC160 molecules did significantly reduce TNF-α-mediated NF-κB activation in 293T cells, as measured by gene reporter and gel mobility shift assays. Since we observed that MC160 decreased other NF-κB activation pathways, namely those activated by receptor-interacting protein, TNF receptor-associated factor 2, NF-κB-inducing kinase, or MyD88, we hypothesized that the MC160 product interfered with I kappa kinase (IKK) activation, an event common to multiple signal transduction pathways. Indeed, MC160 protein expression was associated with a reduction in in vitro IKK kinase activity and IKK subunit phosphorylation. Further, IKK1-IKK2 interactions were not detected in MC160-expressing cells, under conditions demonstrated to induce IKK complex formation, but interactions between the MC160 protein and the major IKK subunits were undetectable. Surprisingly, MC160 expression correlated with a decrease in IKK1, but not IKK2 levels, suggesting a mechanism for MC160 disruption of IKK1-IKK2 interactions. MCV has probably retained its MC160 gene to inhibit NF-κB activation by interfering with signaling via multiple biological mediators. In the context of an MCV infection in vivo, MC160 protein expression may dampen the cellular production of proinflammatory molecules and enhance persistent infections in host keratinocytes. PMID:16378960

  17. Formation and biochemical characterization of tube/pelle death domain complexes: critical regulators of postreceptor signaling by the Drosophila toll receptor.

    PubMed

    Schiffmann, D A; White, J H; Cooper, A; Nutley, M A; Harding, S E; Jumel, K; Solari, R; Ray, K P; Gay, N J

    1999-09-07

    In Drosophila, the Toll receptor signaling pathway is required for embryonic dorso-ventral patterning and at later developmental stages for innate immune responses. It is thought that dimerization of the receptor by binding of the ligand spätzle causes the formation of a postreceptor activation complex at the cytoplasmic surface of the membrane. Two components of this complex are the adaptor tube and protein kinase pelle. These proteins both have "death domains", protein interaction motifs found in a number of signaling pathways, particularly those involved in apoptotic cell death. It is thought that pelle is bound by tube during formation of the activation complexes, and that this interaction is mediated by the death domains. In this paper, we show using the yeast two-hybrid system that the wild-type tube and pelle death domains bind together. Mutant tube proteins which do not support signaling in the embryo are also unable to bind pelle in the 2-hybrid assay. We have purified proteins corresponding to the death domains of tube and pelle and show that these form corresponding heterodimeric complexes in vitro. Partial proteolysis reveals a smaller core consisting of the minimal death domain sequences. We have studied the tube/pelle interaction with the techniques of surface plasmon resonance, analytical ultracentrifugation and isothermal titration calorimetry. These measurements produce a value of K(d) for the complex of about 0.5 microM.

  18. Formation of complex organic molecules in cold objects: the role of gas-phase reactions

    NASA Astrophysics Data System (ADS)

    Balucani, Nadia; Ceccarelli, Cecilia; Taquet, Vianney

    2015-04-01

    While astrochemical models are successful in reproducing many of the observed interstellar species, they have been struggling to explain the observed abundances of complex organic molecules. Current models tend to privilege grain surface over gas-phase chemistry in their formation. One key assumption of those models is that radicals trapped in the grain mantles gain mobility and react on lukewarm ( ≳ 30 K) dust grains. Thus, the recent detections of methyl formate (MF) and dimethyl ether (DME) in cold objects represent a challenge and may clarify the respective role of grain-surface and gas-phase chemistry. We propose here a new model to form DME and MF with gas-phase reactions in cold environments, where DME is the precursor of MF via an efficient reaction overlooked by previous models. Furthermore, methoxy, a precursor of DME, is also synthesized in the gas phase from methanol, which is desorbed by a non-thermal process from the ices. Our new model reproduces fairly well the observations towards L1544. It also explains, in a natural way, the observed correlation between DME and MF. We conclude that gas-phase reactions are major actors in the formation of MF, DME and methoxy in cold gas. This challenges the exclusive role of grain-surface chemistry and favours a combined grain-gas chemistry.

  19. Evolutionarily Conserved Sequence Features Regulate the Formation of the FG Network at the Center of the Nuclear Pore Complex

    PubMed Central

    Peyro, M.; Soheilypour, M.; Lee, B.L.; Mofrad, M.R.K.

    2015-01-01

    The nuclear pore complex (NPC) is the portal for bidirectional transportation of cargos between the nucleus and the cytoplasm. While most of the structural elements of the NPC, i.e. nucleoporins (Nups), are well characterized, the exact transport mechanism is still under much debate. Many of the functional Nups are rich in phenylalanine-glycine (FG) repeats and are believed to play the key role in nucleocytoplasmic transport. We present a bioinformatics study conducted on more than a thousand FG Nups across 252 species. Our results reveal the regulatory role of polar residues and specific sequences of charged residues, named ‘like charge regions’ (LCRs), in the formation of the FG network at the center of the NPC. Positively charged LCRs prepare the environment for negatively charged cargo complexes and regulate the size of the FG network. The low number density of charged residues in these regions prevents FG domains from forming a relaxed coil structure. Our results highlight the significant role of polar interactions in FG network formation at the center of the NPC and demonstrate that the specific localization of LCRs, FG motifs, charged, and polar residues regulate the formation of the FG network at the center of the NPC. PMID:26541386

  20. Studying the association complex formation of atomoxetine and fluvoxamine with eosin Y and its application in their fluorimetric determination

    NASA Astrophysics Data System (ADS)

    Derayea, Sayed M.; Omar, Mahmoud A.; Abu-hassan, Ahmed A.

    2018-03-01

    A simple, sensitive and non-extractive spectrofluorimetric method has been developed and validated for the determination of two psychoanaleptic drugs, atomoxetine and fluvoxamine, in pure forms and pharmaceutical dosage forms. The proposed method is based on the formation of binary complexes between eosin Y and the studied drugs in the presence of a Teorell-Stenhagen buffer. The quenching of the native fluorescence of eosin Y due to complex formation with the studied drugs was measured spectrofluorimetrically at 545 nm after excitation at 302 nm. At the optimum reaction conditions, the fluorescence quenching values (ΔF) and concentrations were rectilinear over the concentration ranges of 0.2-2.2 and 0.3-2.2 µg ml-1 for atomoxetine and fluvoxamine, respectively. The developed method was successfully applied for the determination of the studied drugs in their pharmaceutical formulations with average percentage recoveries of 100.13 ± 0.66 and 99.69 ± 0.44 for atomoxetine and fluvoxamine, respectively (n = 5), without interference from common excipients.

  1. GRAIL gravity observations of the transition from complex crater to peak-ring basin on the Moon: Implications for crustal structure and impact basin formation

    NASA Astrophysics Data System (ADS)

    Baker, David M. H.; Head, James W.; Phillips, Roger J.; Neumann, Gregory A.; Bierson, Carver J.; Smith, David E.; Zuber, Maria T.

    2017-08-01

    High-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) mission provide the opportunity to analyze the detailed gravity and crustal structure of impact features in the morphological transition from complex craters to peak-ring basins on the Moon. We calculate average radial profiles of free-air anomalies and Bouguer anomalies for peak-ring basins, protobasins, and the largest complex craters. Complex craters and protobasins have free-air anomalies that are positively correlated with surface topography, unlike the prominent lunar mascons (positive free-air anomalies in areas of low elevation) associated with large basins. The Bouguer gravity anomaly profiles of complex craters are highly irregular, with central positive anomalies that are generally absent or not clearly tied to interior morphology. In contrast, gravity profiles for peak-ring basins (∼200 km to 580 km) are much more regular and are highly correlated with surface morphology. A central positive Bouguer anomaly is confined within the peak ring and a negative Bouguer anomaly annulus extends from the edge of the positive anomaly outward to about the rim crest. A number of degraded basins lacking interior peak rings have diameters and gravity patterns similar to those of well-preserved peak-ring basins. If these structures represent degraded peak-ring basins, the number of peak-ring basins on the Moon would increase by more than a factor of two to 34. The gravity anomalies within basins are interpreted to be due to uplift of the mantle confined within the peak ring and an annulus of thickened crust between the peak ring and rim crest. We hypothesize that mantle uplift is influenced by interaction between the transient cavity and the mantle. Further, mascon formation is generally disconnected from the number of basin rings formed and occurs over a wide range of basin sizes. These observations have important implications for models of basin and mascon formation on the Moon

  2. GRAIL Gravity Observations of the Transition from Complex Crater to Peak-Ring Basin on the Moon: Implications for Crustal Structure and Impact Basin Formation

    NASA Technical Reports Server (NTRS)

    Baker, David M. H.; Head, James W.; Phillips, Roger J.; Neumann, Gregory A.; Bierson, Carver J.; Smith, David E.; Zuber, Maria T.

    2017-01-01

    High-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) mission provide the opportunity to analyze the detailed gravity and crustal structure of impact features in the morphological transition from complex craters to peak-ring basins on the Moon. We calculate average radial profiles for free-air anomalies and Bouguer anomalies for peak-ring basins, proto-basins, and the largest complex craters. Complex craters and proto-basins have free-air anomalies that are positively correlated with surface topography, unlike the prominent lunar mascons (positive free-air anomalies in areas of low elevation) associated with large basins. The Bouguer gravity anomaly profiles of complex craters are highly irregular, with central positive anomalies that are generally absent or not clearly tied to interior morphology. In contrast, gravity profiles for peak-ring basins (approx. 200 km to 580 km) are much more regular and are highly correlated with surface morphology. A central positive Bouguer anomaly is confined within the peak ring and a negative Bouguer anomaly annulus extends from the edge of the positive anomaly outward to about the rim crest. A number of degraded basins lacking interior peak rings have diameters and gravity patterns similar to those of well-preserved peak-ring basins. If these structures represent degraded peak-ring basins, the number of peak-ring basins on the Moon would increase by more than a factor of two to 34. The gravity anomalies within basins are interpreted to be due to uplift of the mantle confined within the peak ring and an annulus of thickened crust between the peak ring and rim crest. We hypothesize that mantle uplift is influenced by interaction between the transient cavity and the mantle. Further, mascon formation is generally disconnected from the number of basin rings formed and occurs over a wide range of basin sizes. These observations have important implications for models of basin and mascon formation on the

  3. CD8+ TCR repertoire formation is guided primarily by the peptide component of the antigenic complex.

    PubMed

    Koning, Dan; Costa, Ana I; Hoof, Ilka; Miles, John J; Nanlohy, Nening M; Ladell, Kristin; Matthews, Katherine K; Venturi, Vanessa; Schellens, Ingrid M M; Borghans, Jose A M; Kesmir, Can; Price, David A; van Baarle, Debbie

    2013-02-01

    CD8(+) T cells recognize infected or dysregulated cells via the clonotypically expressed αβ TCR, which engages Ag in the form of peptide bound to MHC class I (MHC I) on the target cell surface. Previous studies have indicated that a diverse Ag-specific TCR repertoire can be beneficial to the host, yet the determinants of clonotypic diversity are poorly defined. To better understand the factors that govern TCR repertoire formation, we conducted a comprehensive clonotypic analysis of CD8(+) T cell populations directed against epitopes derived from EBV and CMV. Neither pathogen source nor the restricting MHC I molecule were linked with TCR diversity; indeed, both HLA-A and HLA-B molecules were observed to interact with an overlapping repertoire of expressed TRBV genes. Peptide specificity, however, markedly impacted TCR diversity. In addition, distinct peptides sharing HLA restriction and viral origin mobilized TCR repertoires with distinct patterns of TRBV gene usage. Notably, no relationship was observed between immunodominance and TCR diversity. These findings provide new insights into the forces that shape the Ag-specific TCR repertoire in vivo and highlight a determinative role for the peptide component of the peptide-MHC I complex on the molecular frontline of CD8(+) T cell-mediated immune surveillance.

  4. The eighth fibronectin type III domain of protein tyrosine phosphatase receptor J influences the formation of protein complexes and cell localization.

    PubMed

    Iuliano, Rodolfo; Raso, Cinzia; Quintiero, Alfina; Pera, Ilaria Le; Pichiorri, Flavia; Palumbo, Tiziana; Palmieri, Dario; Pattarozzi, Alessandra; Florio, Tullio; Viglietto, Giuseppe; Trapasso, Francesco; Croce, Carlo Maria; Fusco, Alfredo

    2009-03-01

    Regulation of receptor-type phosphatases can involve the formation of higher-order structures, but the exact role played in this process by protein domains is not well understood. In this study we show the formation of different higher-order structures of the receptor-type phosphatase PTPRJ, detected in HEK293A cells transfected with different PTPRJ expression constructs. In the plasma membrane PTPRJ forms dimers detectable by treatment with the cross-linking reagent BS(3) (bis[sulfosuccinimidyl]suberate). However, other PTPRJ complexes, dependent on the formation of disulfide bonds, are detected by treatment with the oxidant agent H(2)O(2) or by a mutation Asp872Cys, located in the eighth fibronectin type III domain of PTPRJ. A deletion in the eighth fibronectin domain of PTPRJ impairs its dimerization in the plasma membrane and increases the formation of PTPRJ complexes dependent on disulfide bonds that remain trapped in the cytoplasm. The deletion mutant maintains the catalytic activity but is unable to carry out inhibition of proliferation on HeLa cells, achieved by the wild type form, since it does not reach the plasma membrane. Therefore, the intact structure of the eighth fibronectin domain of PTPRJ is critical for its localization in plasma membrane and biological function.

  5. Complex formation equilibria of binary and ternary complexes involving 3,3-bis(1-methylimidazol-2yl)propionic acid and bio-relevant ligands as 1-aminocyclopropane carboxylic acid with reference to plant hormone

    NASA Astrophysics Data System (ADS)

    Shoukry, Mohamed M.; Hassan, Safaa S.

    2014-01-01

    The formation equilibria for the binary complexes of Cu(II) with 1-aminocyclopropane carboxylic acid (ACC) and 3,3-bis(1-methylimidazol-2-yl)propionic acid (BIMP) were investigated. ACC and BIMP form the complexes 1 1 0, 1 2 0 and 1 1 -1. The ternary complexes of Cu(II) with BIMP and biorelevant ligands as some selected amino acids, peptides and DNA constituents are formed in a stepwise mechanism. The stability constants of the complexes formed were determined and their distribution diagrams were evaluated. The kinetics of hydrolysis of glycine methyl ester in presence of [Cu(BIMP)]+ was investigated by pH-stat technique and the mechanism was discussed.

  6. Factors Associated with the Participation of Children with Complex Communication Needs

    ERIC Educational Resources Information Center

    Clarke, M. T.; Newton, C.; Griffiths, T.; Price, K.; Lysley, A.; Petrides, K. V.

    2011-01-01

    The aim of this study was to conduct a preliminary analysis of relations between child and environmental variables, including factors related to communication aid provision, and participation in informal everyday activities in a sample of children with complex communication needs. Ninety-seven caregivers of children provided with communication…

  7. Organizational-economic model of formation of socio-commercial multifunctional complex in the construction of high-rise buildings

    NASA Astrophysics Data System (ADS)

    Kirillova, Ariadna; Prytkova, Oksana O.

    2018-03-01

    The article is devoted to the features of the formation of the organizational and economic model of the construction of a socio-commercial multifunctional complex for high-rise construction. Authors have given examples of high-altitude multifunctional complexes in Moscow, analyzed the advantages and disadvantages in the implementation of multifunctional complexes, stressed the need for a holistic strategic approach, allowing to take into account the prospects for the development of the city and the creation of a comfortable living environment. Based on the analysis of multifunctional complexes features, a matrix of SWOT analysis was compiled. For the development of cities and improving the quality of life of the population, it is proposed to implement a new type of multifunctional complexes of a joint social and commercial direction, including, along with the implementation of office areas - schools, polyclinics, various sports facilities and cultural and leisure centers (theatrical, dance, studio, etc.). The approach proposed in the article for developing the model is based on a comparative evaluation of the multifunctional complex project of a social and commercial direction implemented at the expense of public-private partnership in the form of a concession agreement and a commercial multifunctional complex being built at the expense of the investor. It has been proved by calculations that the obtained indicators satisfy the conditions of expediency of the proposed organizational-economic model and the project of the social and commercial multifunctional complex is effective.

  8. Cognitive complexity of the medical record is a risk factor for major adverse events.

    PubMed

    Roberson, David; Connell, Michael; Dillis, Shay; Gauvreau, Kimberlee; Gore, Rebecca; Heagerty, Elaina; Jenkins, Kathy; Ma, Lin; Maurer, Amy; Stephenson, Jessica; Schwartz, Margot

    2014-01-01

    Patients in tertiary care hospitals are more complex than in the past, but the implications of this are poorly understood as "patient complexity" has been difficult to quantify. We developed a tool, the Complexity Ruler, to quantify the amount of data (as bits) in the patient’s medical record. We designated the amount of data in the medical record as the cognitive complexity of the medical record (CCMR). We hypothesized that CCMR is a useful surrogate for true patient complexity and that higher CCMR correlates with risk of major adverse events. The Complexity Ruler was validated by comparing the measured CCMR with physician rankings of patient complexity on specific inpatient services. It was tested in a case-control model of all patients with major adverse events at a tertiary care pediatric hospital from 2005 to 2006. The main outcome measure was an externally reported major adverse event. We measured CCMR for 24 hours before the event, and we estimated lifetime CCMR. Above empirically derived cutoffs, 24-hour and lifetime CCMR were risk factors for major adverse events (odds ratios, 5.3 and 6.5, respectively). In a multivariate analysis, CCMR alone was essentially as predictive of risk as a model that started with 30-plus clinical factors. CCMR correlates with physician assessment of complexity and risk of adverse events. We hypothesize that increased CCMR increases the risk of physician cognitive overload. An automated version of the Complexity Ruler could allow identification of at-risk patients in real time.

  9. Complex formation of blueberry (Vaccinium angustifolium) anthocyanins during freeze-drying and its influence on their biological activity.

    PubMed

    Correa-Betanzo, Julieta; Padmanabhan, Priya; Corredig, Milena; Subramanian, Jayasankar; Paliyath, Gopinadhan

    2015-03-25

    Biological activity of polyphenols is influenced by their uptake and is highly influenced by their interactions with the food matrix. This study evaluated the complex formation of blueberry polyphenols with fruit matrixes such as pectin and cellulose and their effect on the biological and antiproliferative properties of human colon cell lines HT-29 and CRL 1790. Free or complexed polyphenols were isolated by dialyzing aqueous or methanolic blueberry homogenates. Seven phenolic compounds and thirteen anthocyanins were identified in blueberry extracts. Blueberry extracts showed varying degrees of antioxidant and antiproliferative activities, as well as α-glucosidase activity. Fruit matrix containing cellulose and pectin, or purified polygalacturonic acid and cellulose, did not retain polyphenols and showed very low antioxidant or antiproliferative activities. These findings suggest that interactions between polyphenols and the food matrix may be more complex than a simple association and may play an important role in the bioefficacy of blueberry polyphenols.

  10. Chabazite and dolomite formation in a dolocrete profile: An example of a complex alkaline paragenesis in Lanzarote, Canary Islands

    NASA Astrophysics Data System (ADS)

    Alonso-Zarza, Ana M.; Bustamante, Leticia; Huerta, Pedro; Rodríguez-Berriguete, Álvaro; Huertas, María José

    2016-05-01

    This paper studies the weathering and soil formation processes operating on detrital sediments containing alkaline volcanic rock fragments of the Mirador del Río dolocrete profile. The profile consists of a lower horizon of removilised weathered basalts, an intermediate red sandy mudstones horizon with irregular carbonate layers and a topmost horizon of amalgamated carbonate layers with root traces. Formation occurred in arid to semiarid climates, giving place to a complex mineralogical association, including Mg-carbonates and chabazite, rarely described in cal/dolocretes profiles. Initial vadose weathering processes occurred in the basalts and in directly overlying detrital sediments, producing (Stage 1) red-smectites and dolomicrite. Dominant phreatic (Stage 2) conditions allowed precipitation of coarse-zoned dolomite and chabazite filling porosities. In Stages 3 and 4, mostly pedogenic, biogenic processes played an important role in dolomite and calcite accumulation in the profile. Overall evolution of the profile and its mineralogical association involved initial processes dominated by alteration of host rock, to provide silica and Mg-rich alkaline waters, suitable for chabazite and dolomite formation, without a previous carbonate phase. Dolomite formed both abiogenically and biogenically, but without a previous carbonate precursor and in the absence of evaporites. Dominance of calcite towards the profile top is the result of Mg/Ca decrease in the interstitial meteoric waters due to decreased supply of Mg from weathering, and increased supply of Ca in aeolian dust. Meteoric origin of the water is confirmed by C and O isotope values, which also indicate lack of deep sourced CO2. The dolocrete studied and its complex mineral association reveal the complex interactions that occur at surface during weathering and pedogenesis of basalt-sourced rocks.

  11. Factors Affecting Grammatical and Lexical Complexity of Long-Term L2 Speakers' Oral Proficiency

    ERIC Educational Resources Information Center

    Lahmann, Cornelia; Steinkrauss, Rasmus; Schmid, Monika S.

    2016-01-01

    There remains considerable disagreement about which factors drive second language (L2) ultimate attainment. Age of onset (AO) appears to be a robust factor, lending support to theories of maturational constraints on L2 acquisition. The present study is an investigation of factors that influence grammatical and lexical complexity at the stage of L2…

  12. BetaPIX and GIT1 regulate HGF-induced lamellipodia formation and WAVE2 transport.

    PubMed

    Morimura, Shigeru; Suzuki, Katsuo; Takahashi, Kazuhide

    2009-05-08

    Formation of lamellipodia is the first step during cell migration, and involves actin reassembly at the leading edge of migrating cells through the membrane transport of WAVE2. However, the factors that regulate WAVE2 transport to the cell periphery for initiating lamellipodia formation have not been elucidated. We report here that in human breast cancer MDA-MB-231 cells, the hepatocyte growth factor (HGF) induced the association between the constitutive complex of betaPIX and GIT1 with WAVE2, which was concomitant with the induction of lamellipodia formation and WAVE2 transport. Although depletion of betaPIX by RNA interference abrogated the HGF-induced WAVE2 transport and lamellipodia formation, GIT1 depletion caused HGF-independent WAVE2 transport and lamellipodia formation. Collectively, we suggest that betaPIX releases cells from the GIT1-mediated suppression of HGF-independent responses and recruits GIT1 to WAVE2, thereby facilitating HGF-induced WAVE2 transport and lamellipodia formation.

  13. Differential roles of tissue factor and phosphatidylserine in activation of coagulation.

    PubMed

    Spronk, Henri M H; ten Cate, Hugo; van der Meijden, Paola E J

    2014-05-01

    It has been suggested that the main physiological trigger of coagulation, tissue factor, possesses limited procoagulant activity and occurs in an inactive or so-called encrypted state. For the conversion of encrypted into decrypted tissue factor with sufficient procoagulant activity, four distinct models have been proposed: 1; dimer formation, 2; lipid rafts, 3; disulfide bonds, and 4; phosphatidylserine exposure. Pro and cons can be given for each of these mechanisms of tissue factor encryption/decryption, however, it seems most likely that two or more mechanisms act together in activating the procoagulant activity. The exposure of phosphatidylserine in the outer layer of cell membranes supports coagulation through enhanced formation of the tenase (factors IXa, VIIIa and X) and prothrombinase (factors Xa, Va and prothrombin) complexes. The proposed role for phosphatidylserine in decryption of tissue factor could contribute to the correct orientation of the tissue factor - factor VII complex. Overall, the contribution of both tissue factor and phosphatidylserine to coagulation seems distinct with tissue factor being the physiological activator and phosphatidylserine the driving force of propagation of coagulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Principles for the formation of an effective concept of multifunctional high-rise construction investment projects

    NASA Astrophysics Data System (ADS)

    Beliakov, Sergei

    2018-03-01

    Investment projects of high-rise construction have a number of features that determine specific risks and additional opportunities that require analysis and accounting in the formation of an effective project concept. The most significant features of high-rise construction include long construction time, complexity of technical and technological solutions, complexity of decisions on the organization of construction and operation, high cost of construction and operation, complexity in determining the ratio of areas designed to accommodate different functional areas, when organizing and coordinating the operation of the facility, with internal zoning. Taking into account the specificity of high-rise construction, among the factors determining the effectiveness of projects, it is advisable to consider as key factors: organizational, technological and investment factors. Within the framework of the article, the author singled out key particular functions for each group of factors under consideration, and also developed a system of principles for the formation of an effective concept of multifunctional high-rise construction investment projects, including the principle of logistic efficiency, the principle of optimal functional zoning, the principle of efficiency of equipment use, the principle of optimizing technological processes, the principle maximization of income, the principle of fund management, the principle of risk management . The model of formation of an effective concept of investment projects of multifunctional high-rise construction developed by the author can contribute to the development of methodological tools in the field of managing the implementation of high-rise construction projects, taking into account their specificity in the current economic conditions.

  15. Novel Insights into the Role of Neurospora crassa NDUFAF2, an Evolutionarily Conserved Mitochondrial Complex I Assembly Factor

    PubMed Central

    Pereira, Bruno; Videira, Arnaldo

    2013-01-01

    Complex I deficiency is commonly associated with mitochondrial oxidative phosphorylation diseases. Mutations in nuclear genes encoding structural subunits or assembly factors of complex I have been increasingly identified as the cause of the diseases. One such factor, NDUFAF2, is a paralog of the NDUFA12 structural subunit of the enzyme, but the mechanism by which it exerts its function remains unknown. Herein, we demonstrate that the Neurospora crassa NDUFAF2 homologue, the 13.4L protein, is a late assembly factor that associates with complex I assembly intermediates containing the membrane arm and the connecting part but lacking the N module of the enzyme. Furthermore, we provide evidence that dissociation of the assembly factor is dependent on the incorporation of the putative regulatory module composed of the subunits of 13.4 (NDUFA12), 18.4 (NDUFS6), and 21 (NDUFS4) kDa. Our results demonstrate that the 13.4L protein is a complex I assembly factor functionally conserved from fungi to mammals. PMID:23648483

  16. Study of the various factors influencing deposit formation and operation of gasoline engine injection systems

    NASA Astrophysics Data System (ADS)

    Stepien, Z.

    2016-09-01

    Generally, ethanol fuel emits less pollutants than gasoline, it is completely renewable product and has the potential to reduce greenhouse gases emission but, at the same time can present a multitude of technical challenges to engine operation conditions including creation of very adverse engine deposits. These deposits increasing fuel consumption and cause higher exhaust emissions as well as poor performance in drivability. This paper describes results of research and determination the various factors influencing injector deposits build-up of ethanol-gasoline blends operated engine. The relationship between ethanol-gasoline fuel blends composition, their treatment, engine construction as well as its operation conditions and fuel injectors deposit formation has been investigated. Simulation studies of the deposit formation endanger proper functioning of fuel injection system were carried out at dynamometer engine testing. As a result various, important factors influencing the deposit creation process and speed formation were determined. The ability to control of injector deposits by multifunctional detergent-dispersant additives package fit for ethanol-gasoline blends requirements was also investigated.

  17. Probing the modulated formation of gold nanoparticles-beta-lactoglobulin corona complexes and their applications.

    PubMed

    Yang, Jiang; Wang, Bo; You, Youngsang; Chang, Woo-Jin; Tang, Ke; Wang, Yi-Cheng; Zhang, Wenzhao; Ding, Feng; Gunasekaran, Sundaram

    2017-11-23

    Understanding the interactions between proteins and nanoparticles (NPs) along with the underlying structural and dynamic information is of utmost importance to exploit nanotechnology for biomedical applications. Upon adsorption onto a NP surface, proteins form a well-organized layer, termed the corona, that dictates the identity of the NP-protein complex and governs its biological pathways. Given its high biological relevance, in-depth molecular investigations and applications of NPs-protein corona complexes are still scarce, especially since different proteins form unique corona patterns, making identification of the biomolecular motifs at the interface critical. In this work, we provide molecular insights and structural characterizations of the bio-nano interface of a popular food-based protein, namely bovine beta-lactoglobulin (β-LG), with gold nanoparticles (AuNPs) and report on our investigations of the formation of corona complexes by combined molecular simulations and complementary experiments. Two major binding sites in β-LG were identified as being driven by citrate-mediated electrostatic interactions, while the associated binding kinetics and conformational changes in the secondary structures were also characterized. More importantly, the superior stability of the corona led us to further explore its biomedical applications, such as in the smartphone-based point-of-care biosensing of Escherichia coli (E. coli) and in the computed tomography (CT) of the gastrointestinal (GI) tract through oral administration to probe GI tolerance and functions. Considering their biocompatibility, edible nature, and efficient excretion through defecation, AuNPs-β-LG corona complexes have shown promising perspectives for future in vitro and in vivo clinical settings.

  18. Pseudomonas aeruginosa AmrZ Binds to Four Sites in the algD Promoter, Inducing DNA-AmrZ Complex Formation and Transcriptional Activation.

    PubMed

    Xu, Binjie; Soukup, Randal J; Jones, Christopher J; Fishel, Richard; Wozniak, Daniel J

    2016-10-01

    During late stages of cystic fibrosis pulmonary infections, Pseudomonas aeruginosa often overproduces the exopolysaccharide alginate, protecting the bacterial community from host immunity and antimicrobials. The transcription of the alginate biosynthesis operon is under tight control by a number of factors, including AmrZ, the focus of this study. Interestingly, multiple transcription factors interact with the far-upstream region of this promoter (PalgD), in which one AmrZ binding site has been identified previously. The mechanisms of AmrZ binding and subsequent activation remain unclear and require more-detailed investigation. In this study, in-depth examinations elucidated four AmrZ binding sites, and their disruption eliminated AmrZ binding and promoter activation. Furthermore, our in vitro fluorescence resonance energy transfer experiments suggest that AmrZ holds together multiple binding sites in PalgD and thereafter induces the formation of higher-order DNA-AmrZ complexes. To determine the importance of interactions between those AmrZ oligomers in the cell, a DNA phasing experiment was performed. PalgD transcription was significantly impaired when the relative phase between AmrZ binding sites was reversed (5 bp), while a full-DNA-turn insertion (10 bp) restored promoter activity. Taken together, the investigations presented here provide a deeper mechanistic understanding of AmrZ-mediated binding to PalgD IMPORTANCE: Overproduction of the exopolysaccharide alginate provides protection to Pseudomonas aeruginosa against antimicrobial treatments and is associated with chronic P. aeruginosa infections in the lungs of cystic fibrosis patients. In this study, we combined a variety of microbiological, genetic, biochemical, and biophysical approaches to investigate the activation of the alginate biosynthesis operon promoter by a key transcription factor named AmrZ. This study has provided important new information on the mechanism of activation of this extremely

  19. Host-guest complex formation in cyclotrikis-(1-->6).

    PubMed

    Cescutti, P; Utille, J P; Rizzo, R

    2000-11-17

    The possibility that cyclotrikis-(1-->6)-[alpha-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl] (CGM6) forms inclusion complexes, like cycloamyloses (cyclodextrins), was investigated by means of electrospray mass spectrometry and fluorescence spectroscopy. The complexing ability of both 1-anilinonaphthalene-8-sulfonate (ANS) and 2-p-toluidinylnaphthalene-6-sulfonate (TNS), which were already used with cyclodextrins, was investigated. The former showed very little or no tendency to be complexed by CGM6, while the latter produced detectable adducts with CGM6. Fixed 90 degree angle light scattering experiments supported the findings obtained by molecular modelling calculations, which indicated a polar character for the CGM6 internal cavity. CGM6-TNS complexes were probably formed throughout interaction of the polar regions of the two molecules.

  20. Integrin activation and focal complex formation in cardiac hypertrophy.

    PubMed

    Laser, M; Willey, C D; Jiang, W; Cooper, G; Menick, D R; Zile, M R; Kuppuswamy, D

    2000-11-10

    Cardiac hypertrophy is characterized by both remodeling of the extracellular matrix (ECM) and hypertrophic growth of the cardiocytes. Here we show increased expression and cytoskeletal association of the ECM proteins fibronectin and vitronectin in pressure-overloaded feline myocardium. These changes are accompanied by cytoskeletal binding and phosphorylation of focal adhesion kinase (FAK) at Tyr-397 and Tyr-925, c-Src at Tyr-416, recruitment of the adapter proteins p130(Cas), Shc, and Nck, and activation of the extracellular-regulated kinases ERK1/2. A synthetic peptide containing the Arg-Gly-Asp (RGD) motif of fibronectin and vitronectin was used to stimulate adult feline cardiomyocytes cultured on laminin or within a type-I collagen matrix. Whereas cardiocytes under both conditions showed RGD-stimulated ERK1/2 activation, only collagen-embedded cells exhibited cytoskeletal assembly of FAK, c-Src, Nck, and Shc. In RGD-stimulated collagen-embedded cells, FAK was phosphorylated only at Tyr-397 and c-Src association occurred without Tyr-416 phosphorylation and p130(Cas) association. Therefore, c-Src activation is not required for its cytoskeletal binding but may be important for additional phosphorylation of FAK. Overall, our study suggests that multiple signaling pathways originate in pressure-overloaded heart following integrin engagement with ECM proteins, including focal complex formation and ERK1/2 activation, and many of these pathways can be activated in cardiomyocytes via RGD-stimulated integrin activation.

  1. Integrin activation and focal complex formation in cardiac hypertrophy

    NASA Technical Reports Server (NTRS)

    Laser, M.; Willey, C. D.; Jiang, W.; Cooper, G. 4th; Menick, D. R.; Zile, M. R.; Kuppuswamy, D.

    2000-01-01

    Cardiac hypertrophy is characterized by both remodeling of the extracellular matrix (ECM) and hypertrophic growth of the cardiocytes. Here we show increased expression and cytoskeletal association of the ECM proteins fibronectin and vitronectin in pressure-overloaded feline myocardium. These changes are accompanied by cytoskeletal binding and phosphorylation of focal adhesion kinase (FAK) at Tyr-397 and Tyr-925, c-Src at Tyr-416, recruitment of the adapter proteins p130(Cas), Shc, and Nck, and activation of the extracellular-regulated kinases ERK1/2. A synthetic peptide containing the Arg-Gly-Asp (RGD) motif of fibronectin and vitronectin was used to stimulate adult feline cardiomyocytes cultured on laminin or within a type-I collagen matrix. Whereas cardiocytes under both conditions showed RGD-stimulated ERK1/2 activation, only collagen-embedded cells exhibited cytoskeletal assembly of FAK, c-Src, Nck, and Shc. In RGD-stimulated collagen-embedded cells, FAK was phosphorylated only at Tyr-397 and c-Src association occurred without Tyr-416 phosphorylation and p130(Cas) association. Therefore, c-Src activation is not required for its cytoskeletal binding but may be important for additional phosphorylation of FAK. Overall, our study suggests that multiple signaling pathways originate in pressure-overloaded heart following integrin engagement with ECM proteins, including focal complex formation and ERK1/2 activation, and many of these pathways can be activated in cardiomyocytes via RGD-stimulated integrin activation.

  2. A SPITZER VIEW OF STAR FORMATION IN THE CYGNUS X NORTH COMPLEX

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Beerer, I. M.; Koenig, X. P.; Hora, J. L.

    2010-09-01

    We present new images and photometry of the massive star-forming complex Cygnus X obtained with the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer for Spitzer (MIPS) on board the Spitzer Space Telescope. A combination of IRAC, MIPS, UKIRT Deep Infrared Sky Survey, and Two Micron All Sky Survey data are used to identify and classify young stellar objects (YSOs). Of the 8231 sources detected exhibiting infrared excess in Cygnus X North, 670 are classified as class I and 7249 are classified as class II. Using spectra from the FAST Spectrograph at the Fred L. Whipple Observatory and Hectospecmore » on the MMT, we spectrally typed 536 sources in the Cygnus X complex to identify the massive stars. We find that YSOs tend to be grouped in the neighborhoods of massive B stars (spectral types B0 to B9). We present a minimal spanning tree analysis of clusters in two regions in Cygnus X North. The fraction of infrared excess sources that belong to clusters with {>=}10 members is found to be 50%-70%. Most class II objects lie in dense clusters within blown out H II regions, while class I sources tend to reside in more filamentary structures along the bright-rimmed clouds, indicating possible triggered star formation.« less

  3. Determination of equilibrium and rate constants for complex formation by fluorescence correlation spectroscopy supplemented by dynamic light scattering and Taylor dispersion analysis.

    PubMed

    Zhang, Xuzhu; Poniewierski, Andrzej; Jelińska, Aldona; Zagożdżon, Anna; Wisniewska, Agnieszka; Hou, Sen; Hołyst, Robert

    2016-10-04

    The equilibrium and rate constants of molecular complex formation are of great interest both in the field of chemistry and biology. Here, we use fluorescence correlation spectroscopy (FCS), supplemented by dynamic light scattering (DLS) and Taylor dispersion analysis (TDA), to study the complex formation in model systems of dye-micelle interactions. In our case, dyes rhodamine 110 and ATTO-488 interact with three differently charged surfactant micelles: octaethylene glycol monododecyl ether C 12 E 8 (neutral), cetyltrimethylammonium chloride CTAC (positive) and sodium dodecyl sulfate SDS (negative). To determine the rate constants for the dye-micelle complex formation we fit the experimental data obtained by FCS with a new form of the autocorrelation function, derived in the accompanying paper. Our results show that the association rate constants for the model systems are roughly two orders of magnitude smaller than those in the case of the diffusion-controlled limit. Because the complex stability is determined by the dissociation rate constant, a two-step reaction mechanism, including the diffusion-controlled and reaction-controlled rates, is used to explain the dye-micelle interaction. In the limit of fast reaction, we apply FCS to determine the equilibrium constant from the effective diffusion coefficient of the fluorescent components. Depending on the value of the equilibrium constant, we distinguish three types of interaction in the studied systems: weak, intermediate and strong. The values of the equilibrium constant obtained from the FCS and TDA experiments are very close to each other, which supports the theoretical model used to interpret the FCS data.

  4. Cognitive Complexity of the Medical Record Is a Risk Factor for Major Adverse Events

    PubMed Central

    Roberson, David; Connell, Michael; Dillis, Shay; Gauvreau, Kimberlee; Gore, Rebecca; Heagerty, Elaina; Jenkins, Kathy; Ma, Lin; Maurer, Amy; Stephenson, Jessica; Schwartz, Margot

    2014-01-01

    Context: Patients in tertiary care hospitals are more complex than in the past, but the implications of this are poorly understood because “patient complexity” has been difficult to quantify. Objective: We developed a tool, the Complexity Ruler, to quantify the amount of data (as bits) in the patient’s medical record. We designated the amount of data in the medical record as the cognitive complexity of the medical record (CCMR). We hypothesized that CCMR is a useful surrogate for true patient complexity and that higher CCMR correlates with risk of major adverse events. Design: The Complexity Ruler was validated by comparing the measured CCMR with physician rankings of patient complexity on specific inpatient services. It was tested in a case-control model of all patients with major adverse events at a tertiary care pediatric hospital from 2005 to 2006. Main Outcome Measures: The main outcome measure was an externally reported major adverse event. We measured CCMR for 24 hours before the event, and we estimated lifetime CCMR. Results: Above empirically derived cutoffs, 24-hour and lifetime CCMR were risk factors for major adverse events (odds ratios, 5.3 and 6.5, respectively). In a multivariate analysis, CCMR alone was essentially as predictive of risk as a model that started with 30-plus clinical factors. Conclusions: CCMR correlates with physician assessment of complexity and risk of adverse events. We hypothesize that increased CCMR increases the risk of physician cognitive overload. An automated version of the Complexity Ruler could allow identification of at-risk patients in real time. PMID:24626065

  5. ALMA Reveals Sequential High-mass Star Formation in the G9.62+0.19 Complex

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Tie; Kim, Kee-Tae; Lacy, John

    Stellar feedback from high-mass stars (e.g., H ii regions) can strongly influence the surrounding interstellar medium and regulate star formation. Our new ALMA observations reveal sequential high-mass star formation taking place within one subvirial filamentary clump (the G9.62 clump) in the G9.62+0.19 complex. The 12 dense cores (MM1–MM12) detected by ALMA are at very different evolutionary stages, from the starless core phase to the UC H ii region phase. Three dense cores (MM6, MM7/G, MM8/F) are associated with outflows. The mass–velocity diagrams of the outflows associated with MM7/G and MM8/F can be well-fit by broken power laws. The mass–velocity diagrammore » of the SiO outflow associated with MM8/F breaks much earlier than other outflow tracers (e.g., CO, SO, CS, HCN), suggesting that SiO traces newly shocked gas, while the other molecular lines (e.g., CO, SO, CS, HCN) mainly trace the ambient gas continuously entrained by outflow jets. Five cores (MM1, MM3, MM5, MM9, MM10) are massive starless core candidates whose masses are estimated to be larger than 25 M {sub ☉}, assuming a dust temperature of ≤20 K. The shocks from the expanding H ii regions (“B” and “C”) to the west may have a great impact on the G9.62 clump by compressing it into a filament and inducing core collapse successively, leading to sequential star formation. Our findings suggest that stellar feedback from H ii regions may enhance the star formation efficiency and suppress low-mass star formation in adjacent pre-existing massive clumps.« less

  6. Examining the Factors That Promote Long-Term Change in Elementary Teachers' Instructional Practices: Sustaining Formative Assessment Reform

    ERIC Educational Resources Information Center

    Sherbinko, Thomas, Jr.

    2011-01-01

    The purpose of this holistic case study with a mixed methods approach was two-fold: first, to investigate the extent to which elementary teachers in the BTSD sustained the use of formative assessment reform to regulate instruction, and second, to explore the factors that promoted fidelity to formative assessment reform. Although this study…

  7. Wnt-5a/Frizzled9 Receptor Signaling through the Gαo-Gβγ Complex Regulates Dendritic Spine Formation.

    PubMed

    Ramírez, Valerie T; Ramos-Fernández, Eva; Henríquez, Juan Pablo; Lorenzo, Alfredo; Inestrosa, Nibaldo C

    2016-09-02

    Wnt ligands play crucial roles in the development and regulation of synapse structure and function. Specifically, Wnt-5a acts as a secreted growth factor that regulates dendritic spine formation in rodent hippocampal neurons, resulting in postsynaptic development that promotes the clustering of the PSD-95 (postsynaptic density protein 95). Here, we focused on the early events occurring after the interaction between Wnt-5a and its Frizzled receptor at the neuronal cell surface. Additionally, we studied the role of heterotrimeric G proteins in Wnt-5a-dependent synaptic development. We report that FZD9 (Frizzled9), a Wnt receptor related to Williams syndrome, is localized in the postsynaptic region, where it interacts with Wnt-5a. Functionally, FZD9 is required for the Wnt-5a-mediated increase in dendritic spine density. FZD9 forms a precoupled complex with Gαo under basal conditions that dissociates after Wnt-5a stimulation. Accordingly, we found that G protein inhibition abrogates the Wnt-5a-dependent pathway in hippocampal neurons. In particular, the activation of Gαo appears to be a key factor controlling the Wnt-5a-induced dendritic spine density. In addition, we found that Gβγ is required for the Wnt-5a-mediated increase in cytosolic calcium levels and spinogenesis. Our findings reveal that FZD9 and heterotrimeric G proteins regulate Wnt-5a signaling and dendritic spines in cultured hippocampal neurons. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. The Sharpin interactome reveals a role for Sharpin in lamellipodium formation via the Arp2/3 complex.

    PubMed

    Khan, Meraj H; Salomaa, Siiri I; Jacquemet, Guillaume; Butt, Umar; Miihkinen, Mitro; Deguchi, Takahiro; Kremneva, Elena; Lappalainen, Pekka; Humphries, Martin J; Pouwels, Jeroen

    2017-09-15

    Sharpin, a multifunctional adaptor protein, regulates several signalling pathways. For example, Sharpin enhances signal-induced NF-κB signalling as part of the linear ubiquitin assembly complex (LUBAC) and inhibits integrins, the T cell receptor, caspase 1 and PTEN. However, despite recent insights into Sharpin and LUBAC function, a systematic approach to identify the signalling pathways regulated by Sharpin has not been reported. Here, we present the first 'Sharpin interactome', which identifies a large number of novel potential Sharpin interactors in addition to several known ones. These data suggest that Sharpin and LUBAC might regulate a larger number of biological processes than previously identified, such as endosomal trafficking, RNA processing, metabolism and cytoskeleton regulation. Importantly, using the Sharpin interactome, we have identified a novel role for Sharpin in lamellipodium formation. We demonstrate that Sharpin interacts with Arp2/3, a protein complex that catalyses actin filament branching. We have identified the Arp2/3-binding site in Sharpin and demonstrate using a specific Arp2/3-binding deficient mutant that the Sharpin-Arp2/3 interaction promotes lamellipodium formation in a LUBAC-independent fashion.This article has an associated First Person interview with the first author of the paper. © 2017. Published by The Company of Biologists Ltd.

  9. New insights on the spectrophotometric determination of melatonin pKa values and melatonin-βCD inclusion complex formation constant

    NASA Astrophysics Data System (ADS)

    Zafra-Roldán, A.; Corona-Avendaño, S.; Montes-Sánchez, R.; Palomar-Pardavé, M.; Romero-Romo, M.; Ramírez-Silva, M. T.

    2018-02-01

    Using UV-Vis spectrophotometry a stability study of melatonin at different pH values was done in aqueous media, finding that at acidic pH melatonin is unstable when interacting with the environment, however it becomes stable protecting it from light and oxygen. From the UV-Vis spectra and SQUAD software, melatonin pKa values, in a completely protected aqueous medium, were estimated as 5.777 ± 0.011 and 10.201 ± 0.024. Using the same techniques, the melatonin and β-cyclodextrin inclusion complex formation constants were assessed at pH 3, 7 and 11.5, giving the values of log β = (3.07 ± 0.06), (2.94 ± 0.01) and (3.07 ± 0.06) M- 1, respectively. From the global acidity formation constants and the complexes' formation constants, the molar fractions were determined for each species of MT and MT - βCD, to build the molar fraction-[βCD]-pH 3D diagram and the molar fraction-pH 2D diagrams, where it was possible to observe the predominance of the MT species with and without βCD. A voltammetric study at pH 3, allowed obtaining a value of log β = (3.15 ± 0.01) M- 1, which corroborates that obtained through UV-Vis spectrophotometry, supporting strongly the rationale behind using simple, straightforward techniques.

  10. Design of Safer Flame Retardant Textiles through Inclusion Complex Formation with Cyclodextrins: A Combined Experimental and Modeling Study

    NASA Astrophysics Data System (ADS)

    Zhang, Nanshan

    Triphenyl phosphate (TPP) is widely used as a phosphorus flame retardant. It is also one component of a commercial flame retardant mixture known as Firemaster 550. TPP is likely to be released into the environment due to its high volatility and has been detected at a concentration as high as 47,000 ng/m3 in air. Recent studies have also indicated that FRs like TPP could contribute to obesity and osteoporosis in humans. Cyclodextrins (CDs) are enzymatic degradation products of starch and consist of several (alpha-1,4)-linked alpha-Dglucopyranose units. CDs own a hydrophilic outside and a hydrophobic inner cavity, which enables the formation of non-covalently bonded cyclodextrin inclusion complexes (CD-ICs) with a vast array of molecules. We hypothesize that the formation of inclusion complexes between TPP and cyclodextrins will reduce its exposure yet also retain flame retarding properties of TPP, since the formation of FR-CD-ICs is expected to eliminate unnecessary loss of FRs, especially volatile FR compounds like TPP, and release them only during a fire when they are actually needed. After creating the TPP-beta-CD-IC, we applied it to polyethylene terephthalate (PET) films by a hot press technique. Flame tests indicated TPP-beta-CD-IC exhibited flame resistant performance matching that of neat TPP, even though much less TPP was contained in its beta-CD-IC. Incorporation of FRs and other chemical additives into textile substrates in the form of their crystalline CD-ICs is a promising way to reduce the exposure of hazardous chemicals to humans and to our environment while not impacting their efficacy. Two other parent CDs (alpha-CD and gamma-CD) were applied and their abilities to form ICs with guest TPP were studied. Results from a series of characterization methods, including FTIR, DSC, TGA, XRD and NMR indicated the successful synthesis of TPP-gamma-CD-IC via two routes. However, alpha-CD appears unable to form an IC with TPP, which is likely attributable to a

  11. In vitro platelet activation, aggregation and platelet-granulocyte complex formation induced by surface modified single-walled carbon nanotubes.

    PubMed

    Fent, János; Bihari, Péter; Vippola, Minnamari; Sarlin, Essi; Lakatos, Susan

    2015-08-01

    Surface modification of single-walled carbon nanotubes (SWCNTs) such as carboxylation, amidation, hydroxylation and pegylation is used to reduce the nanotube toxicity and render them more suitable for biomedical applications than their pristine counterparts. Toxicity can be manifested in platelet activation as it has been shown for SWCNTs. However, the effect of various surface modifications on the platelet activating potential of SWCNTs has not been tested yet. In vitro platelet activation (CD62P) as well as the platelet-granulocyte complex formation (CD15/CD41 double positivity) in human whole blood were measured by flow cytometry in the presence of 0.1mg/ml of pristine or various surface modified SWCNTs. The effect of various SWCNTs was tested by whole blood impedance aggregometry, too. All tested SWCNTs but the hydroxylated ones activate platelets and promote platelet-granulocyte complex formation in vitro. Carboxylated, pegylated and pristine SWCNTs induce whole blood aggregation as well. Although pegylation is preferred from biomedical point of view, among the samples tested by us pegylated SWCNTs induced far the most prominent activation and a well detectable aggregation of platelets in whole blood. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Formation of ternary CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) complexes under neutral to weakly alkaline conditions.

    PubMed

    Lee, Jun-Yeop; Yun, Jong-Il

    2013-07-21

    The chemical behavior of ternary Ca-UO2-CO3 complexes was investigated by using time-resolved laser fluorescence spectroscopy (TRLFS) in combination with EDTA complexation at pH 7-9. A novel TRLFS revealed two distinct fluorescence lifetimes of 12.7 ± 0.2 ns and 29.2 ± 0.4 ns for uranyl complexes which were formed increasingly dependent upon the calcium ion concentration, even though nearly indistinguishable fluorescence peak shapes and positions were measured for both Ca-UO2-CO3 complexes. For identifying the stoichiometric number of complexed calcium ions, slope analysis in terms of relative fluorescence intensity versus calcium concentration was employed in a combination with the complexation reaction of CaEDTA(2-) by adding EDTA. The formation of CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) was identified under given conditions and their formation constants were determined at I = 0.1 M Na/HClO4 medium, and extrapolated to infinitely dilute solution using specific ion interaction theory (SIT). As a result, the formation constants for CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) were found to be log β113(0) = 27.27 ± 0.14 and log β213(0) = 29.81 ± 0.19, respectively, providing that the ternary Ca-UO2-CO3 complexes were predominant uranium(vi) species at neutral to weakly alkaline pH in the presence of Ca(2+) and CO3(2-) ions.

  13. A Meier-Gorlin syndrome mutation in a conserved C-terminal helix of Orc6 impedes origin recognition complex formation.

    PubMed

    Bleichert, Franziska; Balasov, Maxim; Chesnokov, Igor; Nogales, Eva; Botchan, Michael R; Berger, James M

    2013-10-08

    In eukaryotes, DNA replication requires the origin recognition complex (ORC), a six-subunit assembly that promotes replisome formation on chromosomal origins. Despite extant homology between certain subunits, the degree of structural and organizational overlap between budding yeast and metazoan ORC has been unclear. Using 3D electron microscopy, we determined the subunit organization of metazoan ORC, revealing that it adopts a global architecture very similar to the budding yeast complex. Bioinformatic analysis extends this conservation to Orc6, a subunit of somewhat enigmatic function. Unexpectedly, a mutation in the Orc6 C-terminus linked to Meier-Gorlin syndrome, a dwarfism disorder, impedes proper recruitment of Orc6 into ORC; biochemical studies reveal that this region of Orc6 associates with a previously uncharacterized domain of Orc3 and is required for ORC function and MCM2-7 loading in vivo. Together, our results suggest that Meier-Gorlin syndrome mutations in Orc6 impair the formation of ORC hexamers, interfering with appropriate ORC functions. DOI:http://dx.doi.org/10.7554/eLife.00882.001.

  14. Studying the association complex formation of atomoxetine and fluvoxamine with eosin Y and its application in their fluorimetric determination

    PubMed Central

    Omar, Mahmoud A.; Abu-hassan, Ahmed A.

    2018-01-01

    A simple, sensitive and non-extractive spectrofluorimetric method has been developed and validated for the determination of two psychoanaleptic drugs, atomoxetine and fluvoxamine, in pure forms and pharmaceutical dosage forms. The proposed method is based on the formation of binary complexes between eosin Y and the studied drugs in the presence of a Teorell–Stenhagen buffer. The quenching of the native fluorescence of eosin Y due to complex formation with the studied drugs was measured spectrofluorimetrically at 545 nm after excitation at 302 nm. At the optimum reaction conditions, the fluorescence quenching values (ΔF) and concentrations were rectilinear over the concentration ranges of 0.2–2.2 and 0.3–2.2 µg ml−1 for atomoxetine and fluvoxamine, respectively. The developed method was successfully applied for the determination of the studied drugs in their pharmaceutical formulations with average percentage recoveries of 100.13 ± 0.66 and 99.69 ± 0.44 for atomoxetine and fluvoxamine, respectively (n = 5), without interference from common excipients. PMID:29657744

  15. Crystallization of a 2:2 complex of granulocyte-colony stimulating factor (GCSF) with the ligand-binding region of the GCSF receptor

    PubMed Central

    Honjo, Eijiro; Tamada, Taro; Maeda, Yoshitake; Koshiba, Takumi; Matsukura, Yasuko; Okamoto, Tomoyuki; Ishibashi, Matsujiro; Tokunaga, Masao; Kuroki, Ryota

    2005-01-01

    The granulocyte-colony stimulating factor (GCSF) receptor receives signals for regulating the maturation, proliferation and differentiation of the precursor cells of neutrophilic granulocytes. The signalling complex composed of two GCSFs (GCSF, 19 kDa) and two GCSF receptors (GCSFR, 34 kDa) consisting of an Ig-like domain and a cytokine-receptor homologous (CRH) domain was crystallized. A crystal of the complex was grown in 1.0 M sodium formate and 0.1 M sodium acetate pH 4.6 and belongs to space group P41212 (or its enantiomorph P43212), with unit-cell parameters a = b = 110.1, c = 331.8 Å. Unfortunately, this crystal form did not diffract beyond 5 Å resolution. Since the heterogeneity of GCSF receptor appeared to prevent the growth of good-quality crystals, the GCSF receptor was fractionated by anion-exchange chromatography. Crystals of the GCSF–fractionated GCSF receptor complex were grown as a new crystal form in 0.2 M ammonium phosphate. This new crystal form diffracted to beyond 3.0 Å resolution and belonged to space group P3121 (or its enantiomorph P3221), with unit-cell parameters a = b = 134.8, c = 105.7 Å. PMID:16511159

  16. Structural analysis of the Sil1-Bip complex reveals the mechanism for Sil1 to function as a nucleotide-exchange factor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yan, Ming; Li, Jingzhi; Sha, Bingdong

    2013-01-16

    Sil1 functions as a NEF (nucleotide-exchange factor) for the ER (endoplasmic reticulum) Hsp70 (heat-shock protein of 70 kDa) Bip in eukaryotic cells. Sil1 may catalyse the ADP release from Bip by interacting directly with the ATPase domain of Bip. In the present study we show the complex crystal structure of the yeast Bip and the NEF Sil1 at the resolution of 2.3 {angstrom} (1 {angstrom} = 0.1 nm). In the Sil1-Bip complex structure, the Sil1 molecule acts as a 'clamp' which binds lobe IIb of the Bip ATPase domain. The binding of Sil1 causes the rotation of lobe IIb {approx}more » 13.5{sup o} away from the ADP-binding pocket. The complex formation also induces lobe Ib to swing in the opposite direction by {approx} 3.7{sup o}. These conformational changes open up the nucleotide-binding pocket in the Bip ATPase domain and disrupt the hydrogen bonds between Bip and bound ADP, which may catalyse ADP release. Mutation of the Sil1 residues involved in binding the Bip ATPase domain compromise the binding affinity of Sil1 to Bip, and these Sil1 mutants also abolish the ability to stimulate the ATPase activity of Bip.« less

  17. Dynamics of Research Team Formation in Complex Networks

    NASA Astrophysics Data System (ADS)

    Sun, Caihong; Wan, Yuzi; Chen, Yu

    Most organizations encourage the formation of teams to accomplish complicated tasks, and vice verse, effective teams could bring lots benefits and profits for organizations. Network structure plays an important role in forming teams. In this paper, we specifically study the dynamics of team formation in large research communities in which knowledge of individuals plays an important role on team performance and individual utility. An agent-based model is proposed, in which heterogeneous agents from research communities are described and empirically tested. Each agent has a knowledge endowment and a preference for both income and leisure. Agents provide a variable input (‘effort’) and their knowledge endowments to production. They could learn from others in their team and those who are not in their team but have private connections in community to adjust their own knowledge endowment. They are allowed to join other teams or work alone when it is welfare maximizing to do so. Various simulation experiments are conducted to examine the impacts of network topology, knowledge diffusion among community network, and team output sharing mechanisms on the dynamics of team formation.

  18. [Clinical features and risk factors of biloma formation after transcatheter arterial chemoembolization].

    PubMed

    Zhaolin, Zeng; Xuelian, Liu; Wensou, Huang; Mingyue, Cai; Haofan, Wang; Ming'an, Li; Hong, Shan; Zhu, Kangshun

    2015-04-07

    To explore the risk factors, treatment and outcomes of biloma after transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). A total of 481 patients with a diagnosis of HCC underwent TACE at our hospital from January 2011 to December 2013. Biloma was tracked by the follow-ups of computed tomography or magnetic resonance imaging (CT/ MRI) . Retrospective analyses were conducted for their clinical features, treatments and prognosis. The statistically significant factors for univariate analysis were introduced into Logistic regression models for multivariate analysis to obtain the risk factors of biloma post-TACE. There were 43 cases of complicated biloma after TACE. And 38 patients (88.4% ) developed biloma at 0.5-3 months post-TACE while another 5 (9.7%) did so at 3-5 months. The multivariate analysis showed that bile duct dilation, a history of hepatectomy prior to TACE, use of polyvinyl alcohol (PVA) particles and nonsuperselective embolization were the risk factors of biloma formation after TACE. Among 9 symptomatics, there were jaundice (n =2) and fever (n =7). The diameter of bilomas was (8.07 ± 3.53) cm for 9 symptomatics and (2.81 ± 1.26) cm for 35 asymptomatics. And the difference was statistically significant (P <0. 01). Nine symptomatic patients underwent percutaneous drainage with tube and biloma diminished (n = 7) and even vanished (n = 2). Only conservative treatment was offered for 35 asymptomatics. During the follow-ups, it showed no change (n = 24) , diminishing (n = 8) and disappearance (n = 2). One case died from a greatly enlarged biloma due to hepatic failure and septic shock via a rupture into abdominal cavity and choleperitonitis. The risk factors of biloma formation after TACE for HCC are bile duct dilation, a history of hepatectomy before TACE, use of PVA particles and nonsuperselective embolization. For symptomatics, drainage must be performed timely and the prognosis is fair. For asymptomatics, regular imaging

  19. Outcomes Following Three-Factor Inactive Prothrombin Complex Concentrate Versus Recombinant Activated Factor VII Administration During Cardiac Surgery.

    PubMed

    Harper, Patrick C; Smith, Mark M; Brinkman, Nathan J; Passe, Melissa A; Schroeder, Darrell R; Said, Sameh M; Nuttall, Gregory A; Oliver, William C; Barbara, David W

    2018-02-01

    To compare outcomes following inactive prothrombin complex concentrate (PCC) or recombinant activated factor VII (rFVIIa) administration during cardiac surgery. Retrospective propensity-matched analysis. Academic tertiary-care center. Patients undergoing cardiac surgery requiring cardiopulmonary bypass who received either rFVIIa or the inactive 3-factor PCC. Outcomes following intraoperative administration of rFVIIa (263) or factor IX complex (72) as rescue therapy to treat bleeding. In the 24 hours after surgery, propensity-matched patients receiving PCC versus rFVIIa had significantly less chest tube outputs (median difference -464 mL, 95% confidence interval [CI] -819 mL to -110 mL), fresh frozen plasma transfusion rates (17% v 38%, p = 0.028), and platelet transfusion rates (26% v 49%, p = 0.027). There were no significant differences between propensity-matched groups in postoperative stroke, deep venous thrombosis, pulmonary embolism, myocardial infarction, or intracardiac thrombus. Postoperative dialysis was significantly less likely in patients administered PCC versus rFVIIa following propensity matching (odds ratio = 0.3, 95% CI 0.1-0.7). No significant difference in 30-day mortality in patients receiving PCC versus rFVIIa was present following propensity matching. Use of rFVIIa versus inactive PCCs was significantly associated with renal failure requiring dialysis and increased postoperative bleeding and transfusions. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Concerted formation of macromolecular Suppressor–mutator transposition complexes

    PubMed Central

    Raina, Ramesh; Schläppi, Michael; Karunanandaa, Balasulojini; Elhofy, Adam; Fedoroff, Nina

    1998-01-01

    Transposition of the maize Suppressor–mutator (Spm) transposon requires two element-encoded proteins, TnpA and TnpD. Although there are multiple TnpA binding sites near each element end, binding of TnpA to DNA is not cooperative, and the binding affinity is not markedly affected by the number of binding sites per DNA fragment. However, intermolecular complexes form cooperatively between DNA fragments with three or more TnpA binding sites. TnpD, itself not a sequence-specific DNA-binding protein, binds to TnpA and stabilizes the TnpA–DNA complex. The high redundancy of TnpA binding sites at both element ends and the protein–protein interactions between DNA-bound TnpA complexes and between these and TnpD imply a concerted transition of the element from a linear to a protein crosslinked transposition complex within a very narrow protein concentration range. PMID:9671711

  1. Fluorimetric determination of some sulfur containing compounds through complex formation with terbium (Tb+3) and uranium (U+3).

    PubMed

    Taha, Elham Anwer; Hassan, Nagiba Yehya; Aal, Fahima Abdel; Fattah, Laila El-Sayed Abdel

    2007-05-01

    Two simple, sensitive and specific fluorimetric methods have been developed for the determination of some sulphur containing compounds namely, Acetylcysteine (Ac), Carbocisteine (Cc) and Thioctic acid (Th) using terbium Tb+3 and uranium U+3 ions as fluorescent probes. The proposed methods involve the formation of a ternary complex with Tb+3 in presence of Tris-buffer method (I) and a binary complex with aqueous uranyl acetate solution method (II). The fluorescence quenching of Tb+3 at 510, 488 and 540 nm (lambda(ex) 250, 241 and 268 nm) and of uranyl acetate at 512 nm (lambda(ex) 240 nm) due to the complex formation was quantitatively measured for Ac, Cc and Th, respectively. The reaction conditions and the fluorescence spectral properties of the complexes have been investigated. Under the described conditions, the proposed methods were applicable over the concentration range (0.2-2.5 microg ml(-1)), (1-4 microg ml(-1)) and (0.5-3.5 microg ml(-1)) with mean percentage recoveries 99.74+/-0.36, 99.70+/-0.52 and 99.43+/-0.23 for method (I) and (0.5-6 microg ml(-1)), (0.5-5 microg ml(-1)), and (1-6 microg ml(-1)) with mean percentage recoveries 99.38+/-0.20, 99.82+/-0.28 and 99.93+/-0.32 for method (II), for the three cited drugs, respectively. The proposed methods were successfully applied for the determination of the studied compounds in bulk powders and in pharmaceutical formulations, as well as in presence of their related substances. The results obtained were found to be in agree statistically with those obtained by official and reported ones. The two methods were validated according to USP guidelines and also assessed by applying the standard addition technique.

  2. A Simple Explanation of Complexation

    ERIC Educational Resources Information Center

    Elliott, J. Richard

    2010-01-01

    The topics of solution thermodynamics, activity coefficients, and complex formation are introduced through computational exercises and sample applications. The presentation is designed to be accessible to freshmen in a chemical engineering computations course. The MOSCED model is simplified to explain complex formation in terms of hydrogen…

  3. Computer-aided molecular modeling techniques for predicting the stability of drug cyclodextrin inclusion complexes in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Faucci, Maria Teresa; Melani, Fabrizio; Mura, Paola

    2002-06-01

    Molecular modeling was used to investigate factors influencing complex formation between cyclodextrins and guest molecules and predict their stability through a theoretical model based on the search for a correlation between experimental stability constants ( Ks) and some theoretical parameters describing complexation (docking energy, host-guest contact surfaces, intermolecular interaction fields) calculated from complex structures at a minimum conformational energy, obtained through stochastic methods based on molecular dynamic simulations. Naproxen, ibuprofen, ketoprofen and ibuproxam were used as model drug molecules. Multiple Regression Analysis allowed identification of the significant factors for the complex stability. A mathematical model ( r=0.897) related log Ks with complex docking energy and lipophilic molecular fields of cyclodextrin and drug.

  4. Band registration of tuneable frame format hyperspectral UAV imagers in complex scenes

    NASA Astrophysics Data System (ADS)

    Honkavaara, Eija; Rosnell, Tomi; Oliveira, Raquel; Tommaselli, Antonio

    2017-12-01

    A recent revolution in miniaturised sensor technology has provided markets with novel hyperspectral imagers operating in the frame format principle. In the case of unmanned aerial vehicle (UAV) based remote sensing, the frame format technology is highly attractive in comparison to the commonly utilised pushbroom scanning technology, because it offers better stability and the possibility to capture stereoscopic data sets, bringing an opportunity for 3D hyperspectral object reconstruction. Tuneable filters are one of the approaches for capturing multi- or hyperspectral frame images. The individual bands are not aligned when operating a sensor based on tuneable filters from a mobile platform, such as UAV, because the full spectrum recording is carried out in the time-sequential principle. The objective of this investigation was to study the aspects of band registration of an imager based on tuneable filters and to develop a rigorous and efficient approach for band registration in complex 3D scenes, such as forests. The method first determines the orientations of selected reference bands and reconstructs the 3D scene using structure-from-motion and dense image matching technologies. The bands, without orientation, are then matched to the oriented bands accounting the 3D scene to provide exterior orientations, and afterwards, hyperspectral orthomosaics, or hyperspectral point clouds, are calculated. The uncertainty aspects of the novel approach were studied. An empirical assessment was carried out in a forested environment using hyperspectral images captured with a hyperspectral 2D frame format camera, based on a tuneable Fabry-Pérot interferometer (FPI) on board a multicopter and supported by a high spatial resolution consumer colour camera. A theoretical assessment showed that the method was capable of providing band registration accuracy better than 0.5-pixel size. The empirical assessment proved the performance and showed that, with the novel method, most parts of

  5. Growth Factor Signaling and Memory Formation: Temporal and Spatial Integration of a Molecular Network

    ERIC Educational Resources Information Center

    Kopec, Ashley M.; Carew, Thomas J.

    2013-01-01

    Growth factor (GF) signaling is critically important for developmental plasticity. It also plays a crucial role in adult plasticity, such as that required for memory formation. Although different GFs interact with receptors containing distinct types of kinase domains, they typically signal through converging intracellular cascades (e.g.,…

  6. Preparation and properties of chitosan-metal complex: Some factors influencing the adsorption capacity for dyes in aqueous solution.

    PubMed

    Rashid, Sadia; Shen, Chensi; Yang, Jing; Liu, Jianshe; Li, Jing

    2018-04-01

    Chitosan-metal complexes have been widely studied in wastewater treatment, but there are still various factors in complex preparation which are collectively responsible for improving the adsorption capacity need to be further studied. Thus, this study investigates the factors affecting the adsorption ability of chitosan-metal complex adsorbents, including various kinds of metal centers, different metal salts and crosslinking degree. The results show that the chitosan-Fe(III) complex prepared by sulfate salts exhibited the best adsorption efficiency (100%) for various dyes in very short time duration (10min), and its maximum adsorption capacity achieved 349.22mg/g. The anion of the metal salt which was used in preparation played an important role to enhance the adsorption ability of chitosan-metal complex. SO 4 2- ions not only had the effect of crosslinking through electrostatic interaction with amine group of chitosan polymer, but also could facilitate the chelation of metal ions with chitosan polymer during the synthesis process. Additionally, the pH sensitivity and the sensitivity of ionic environment for chitosan-metal complex were analyzed. We hope that these factors affecting the adsorption of the chitosan-metal complex can help not only in optimizing its use but also in designing new chitosan-metal based complexes. Copyright © 2017. Published by Elsevier B.V.

  7. Chirality-selected phase behaviour in ionic polypeptide complexes

    DOE PAGES

    Perry, Sarah L.; Leon, Lorraine; Hoffmann, Kyle Q.; ...

    2015-01-14

    In this study, polyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation. Here we demonstrate that chirality determines the state of polyelectrolyte complexes, formed from mixing dilute solutions of oppositely charged polypeptides, via a combination of electrostatic and hydrogen-bonding interactions. Fluid complexes occur when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen-bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with amore » β-sheet structure. Analogous behaviour occurs in micelles formed from polypeptide block copolymers with polyethylene oxide, where assembly into aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in polyelectrolyte complexation.« less

  8. In vivo characterization of the Drosophila mRNA 3′ end processing core cleavage complex

    PubMed Central

    Michalski, Daniel; Steiniger, Mindy

    2015-01-01

    A core cleavage complex (CCC) consisting of CPSF73, CPSF100, and Symplekin is required for cotranscriptional 3′ end processing of all metazoan pre-mRNAs, yet little is known about the in vivo molecular interactions within this complex. The CCC is a component of two distinct complexes, the cleavage/polyadenylation complex and the complex that processes nonpolyadenylated histone pre-mRNAs. RNAi-depletion of CCC factors in Drosophila culture cells causes reduction of CCC processing activity on histone mRNAs, resulting in read through transcription. In contrast, RNAi-depletion of factors only required for histone mRNA processing allows use of downstream cryptic polyadenylation signals to produce polyadenylated histone mRNAs. We used Dmel-2 tissue culture cells stably expressing tagged CCC components to determine that amino acids 272–1080 of Symplekin and the C-terminal approximately 200 amino acids of both CPSF73 and CPSF100 are required for efficient CCC formation in vivo. Additional experiments reveal that the C-terminal 241 amino acids of CPSF100 are sufficient for histone mRNA processing indicating that the first 524 amino acids of CPSF100 are dispensable for both CCC formation and histone mRNA 3′ end processing. CCCs containing deletions of Symplekin lacking the first 271 amino acids resulted in dramatic increased use of downstream polyadenylation sites for histone mRNA 3′ end processing similar to RNAi-depletion of histone-specific 3′ end processing factors FLASH, SLBP, and U7 snRNA. We propose a model in which CCC formation is mediated by CPSF73, CPSF100, and Symplekin C-termini, and the N-terminal region of Symplekin facilitates cotranscriptional 3′ end processing of histone mRNAs. PMID:26081560

  9. Tetrapeptide-coumarin conjugate 3D networks based on hydrogen-bonded charge transfer complexes: gel formation and dye release.

    PubMed

    Guo, Zongxia; Gong, Ruiying; Jiang, Yi; Wan, Xiaobo

    2015-08-14

    Oligopeptide-based derivatives are important synthons for bio-based functional materials. In this article, a Gly-(L-Val)-Gly-(L-Val)-coumarin (GVGV-Cou) conjugate was synthesized, which forms 3D networks in ethanol. The gel nanostructures were characterized by UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD), SEM and TEM. It is suggested that the formation of charge transfer (CT) complexes between the coumarin moieties is the main driving force for the gel formation. The capability of the gel to encapsulate and release dyes was explored. Both Congo Red (CR) and Methylene Blue (MB) can be trapped in the CT gel matrix and released over time. The present gel might be used as a functional soft material for guest encapsulation and release.

  10. Prevalence, pathophysiological mechanisms and factors affecting urolithiasis.

    PubMed

    Khan, Aslam

    2018-05-01

    The formation of urinary stone, urolithiasis, is one the oldest known disease affecting human throughout different civilizations and times. The exact pathophysiological mechanism of urolithiasis is not yet clear, as these calculi are of various types and too complex for simple understanding. A single theory cannot explain its formation; therefore, different theories are presented in various times for its explanation like free particle, fixed particle, Randall's plaque theory. In addition, various factors and components are identified that play an important role in the formation of these urinary calculi. In this review, composition of kidney stones, its prevalence/incidence, explanation of pathophysiological mechanisms and role of various factors; urinary pH, uric acid, parathyroid hormone, citrate, oxalate, calcium and macromolecules; osteopontin, matrix Gla protein, kidney injury molecules, urinary prothrombin fragment-1, Tamm-Horsfall protein, inter-α-inhibitors, have been discussed in detail.

  11. Star Formation and Young Population of the H II Complex Sh2-294

    NASA Astrophysics Data System (ADS)

    Samal, M. R.; Pandey, A. K.; Ojha, D. K.; Chauhan, N.; Jose, J.; Pandey, B.

    2012-08-01

    The Sh2-294 H II region ionized by a single B0V star features several infrared excess sources, a photodissociation region, and also a group of reddened stars at its border. The star formation scenario in this region seems to be quite complex. In this paper, we present follow-up results of Sh2-294 H II region at 3.6, 4.5, 5.8, and 8.0 μm observed with the Spitzer Space Telescope Infrared Array Camera (IRAC), coupled with H2 (2.12 μm) observation, to characterize the young population of the region and to understand its star formation history. We identified 36 young stellar object (YSO, Class I, Class II, and Class I/II) candidates using IRAC color-color diagrams. It is found that Class I sources are preferentially located at the outskirts of the H II region and associated with enhanced H2 emission; none of them are located near the central cluster. Combining the optical to mid-infrared (MIR) photometry of the YSO candidates and using the spectral energy distribution fitting models, we constrained stellar parameters and the evolutionary status of 33 YSO candidates. Most of them are interpreted by the model as low-mass (<4 M ⊙) YSOs; however, we also detected a massive YSO (~9 M ⊙) of Class I nature, embedded in a cloud of visual extinction of ~24 mag. Present analysis suggests that the Class I sources are indeed a younger population of the region relative to Class II sources (age ~ 4.5 × 106 yr). We suggest that the majority of the Class I sources, including the massive YSOs, are second-generation stars of the region whose formation is possibly induced by the expansion of the H II region powered by a ~4 × 106 yr B0 main-sequence star.

  12. Neuromechanical factors involved in the formation and propulsion of fecal pellets in the guinea-pig colon.

    PubMed

    Costa, M; Wiklendt, L; Simpson, P; Spencer, N J; Brookes, S J; Dinning, P G

    2015-10-01

    The neuromechanical processes involved in the formation and propulsion of fecal pellets remain incompletely understood. We analyzed motor patterns in isolated segments of the guinea-pig proximal and distal colon, using video imaging, during oral infusion of liquid, viscous material, or solid pellets. Colonic migrating motor complexes (CMMCs) in the proximal colon divided liquid or natural semisolid contents into elongated shallow boluses. At the colonic flexure these boluses were formed into shorter, pellet-shaped boluses. In the non-distended distal colon, spontaneous CMMCs produced small dilations. Both high- and low-viscosity infusions evoked a distinct motor pattern that produced pellet-shaped boluses. These were propelled at speeds proportional to their surface area. Solid pellets were propelled at a speed that increased with diameter, to a maximum that matched the diameter of natural pellets. Pellet speed was reduced by increasing resistive load. Tetrodotoxin blocked all propulsion. Hexamethonium blocked normal motor patterns, leaving irregular propagating contractions, indicating the existence of neural pathways that did not require nicotinic transmission. Colonic migrating motor complexes are responsible for the slow propulsion of the soft fecal content in the proximal colon, while the formation of pellets at the colonic flexure involves a content-dependent mechanism in combination with content-independent spontaneous CMMCs. Bolus size and consistency affects propulsion speed suggesting that propulsion is not a simple reflex but rather a more complex process involving an adaptable neuromechanical loop. © 2015 John Wiley & Sons Ltd.

  13. Online or Face-to-Face Learning? Exploring the Personal Factors that Predict Students' Choice of Instructional Format

    ERIC Educational Resources Information Center

    Artino, Anthony R., Jr.

    2010-01-01

    Notwithstanding the growth of online learning, little is known about the personal factors that predict student decisions to enroll in online courses. This study examined the relations between several personal factors and students' choice of instructional format. After completing an online course, service academy undergraduates (N = 564) completed…

  14. Struvite crystal growth inhibition by trisodium citrate and the formation of chemical complexes in growth solution

    NASA Astrophysics Data System (ADS)

    Prywer, Jolanta; Mielniczek-Brzóska, Ewa; Olszynski, Marcin

    2015-05-01

    Effect of trisodium citrate on the crystallization of struvite was studied. To evaluate such an effect an experiment of struvite growth from artificial urine was performed. The investigations are related to infectious urinary stones formation. The crystallization process was induced by the addition of aqueous ammonia solution to mimic the bacterial activity. The spectrophotometric results demonstrate that trisodium citrate increases induction time with respect to struvite formation and decreases the growth efficiency of struvite. The inhibitory effect of trisodium citrate on the nucleation and growth of struvite is explained in base of chemical speciation analysis. Such an analysis demonstrates that the inhibitory effect is related with the fact that trisodium citrate binds NH4 + and Mg2+ ions in the range of pH from 7 to 9.5 characteristic for struvite precipitation. The most important is the MgCit- complex whose concentration strongly depends on an increase in pH rather than on an increase in citrate concentrations.

  15. TAF11 assembles RISC loading complex to enhance RNAi efficiency

    PubMed Central

    Liang, Chunyang; Wang, Yibing; Murota, Yukiko; Liu, Xiang; Smith, Dean; Siomi, Mikiko C.; Liu, Qinghua

    2015-01-01

    SUMMARY Assembly of the RNA-induced silencing complex (RISC) requires formation of the RISC loading complex (RLC), which contains Dicer-2(Dcr-2)-R2D2 complex and recruits duplex siRNA to Ago2 in Drosophila melanogaster. However, the precise composition and action mechanism of Drosophila RLC remain unclear. Here, we identified the missing factor of RLC as TATA-binding protein associated factor 11 (TAF11) by genetic screen. Although an annotated nuclear transcription factor, we found that TAF11 also associated with Dcr-2/R2D2 and localized to cytoplasmic D2 bodies. Consistent with defective RLC assembly in taf11−/− ovary extract, we reconstituted the RLC in vitro using recombinant Dcr-2-R2D2 complex, TAF11, and duplex siRNA. Furthermore, we showed that TAF11 tetramer facilitates Dcr-2-R2D2 tetramerization to enhance siRNA binding and RISC loading activities. Together, our genetic and biochemical studies define the molecular nature of Drosophila RLC and elucidate a novel cytoplasmic function of TAF11 in organizing RLC assembly to enhance RNAi efficiency. PMID:26257286

  16. Formation of ethylene glycol and other complex organic molecules in star-forming regions

    NASA Astrophysics Data System (ADS)

    Rivilla, V. M.; Beltrán, M. T.; Cesaroni, R.; Fontani, F.; Codella, C.; Zhang, Q.

    2017-02-01

    Context. The detection of complex organic molecules related with prebiotic chemistry in star-forming regions allows us to investigate how the basic building blocks of life are formed. Aims: Ethylene glycol (CH2OH)2 is the simplest sugar alcohol and the reduced alcohol of the simplest sugar glycoladehyde (CH2OHCHO). We study the molecular abundance and spatial distribution of (CH2OH)2, CH2OHCHO and other chemically related complex organic species (CH3OCHO, CH3OCH3, and C2H5OH) towards the chemically rich massive star-forming region G31.41+0.31. Methods: We analyzed multiple single-dish (Green Bank Telescope and IRAM 30 m) and interferometric (Submillimeter Array) spectra towards G31.41+0.31, covering a range of frequencies from 45 to 258 GHz. We fitted the observed spectra with a local thermodynamic equilibrium (LTE) synthetic spectra, and obtained excitation temperatures and column densities. We compared our findings in G31.41+0.31 with the results found in other environments, including low- and high-mass star-forming regions, quiescent clouds and comets. Results: We report for the first time the presence of the aGg' conformer of (CH2OH)2 towards G31.41+0.31, detecting more than 30 unblended lines. We also detected multiple transitions of other complex organic molecules such as CH2OHCHO, CH3OCHO, CH3OCH3, and C2H5OH. The high angular resolution images show that the (CH2OH)2 emission is very compact, peaking towards the maximum of the 1.3 mm continuum. These observations suggest that low abundance complex organic molecules, like (CH2OH)2 or CH2OHCHO, are good probes of the gas located closer to the forming stars. Our analysis confirms that (CH2OH)2 is more abundant than CH2OHCHO in G31.41+0.31, as previously observed in other interstellar regions. Comparing different star-forming regions we find evidence of an increase of the (CH2OH)2/CH2OHCHO abundance ratio with the luminosity of the source. The CH3OCH3/CH3OCHO and (CH2OH)2/C2H5OH ratios are nearly constant with

  17. Preparation of microcapsules by complex coacervation of gum Arabic and chitosan.

    PubMed

    Butstraen, Chloé; Salaün, Fabien

    2014-01-01

    Gum Arabic-chitosan microcapsules containing a commercially available blend of triglycerides (Miglyol 812 N) as core phase were synthesized by complex coacervation. This study was conducted to clarify the influence of different parameters on the encapsulation process, i.e. during the emulsion formation steps and during the shell formation, using conductometry, zeta potential, surface and interface tension measurement and Fourier-transform infrared spectroscopy. By carefully analyzing the influencing factors including phase volume ratio, stirring rate and time, pH, reaction time, biopolymer ratio and crosslinking effect, the optimum synthetic conditions were found out. For the emulsion step, the optimum phase volume ratio chosen was 0.10 and an emulsion time of 15 min at 11,000 rpm was selected. The results also indicated that the optimum formation of these complexes appears at a pH value of 3.6 and a weight ratio of chitosan to gum Arabic mixtures of 0.25. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Anaerobic Formate and Hydrogen Metabolism.

    PubMed

    Pinske, Constanze; Sawers, R Gary

    2016-10-01

    Numerous recent developments in the biochemistry, molecular biology, and physiology of formate and H2 metabolism and of the [NiFe]-hydrogenase (Hyd) cofactor biosynthetic machinery are highlighted. Formate export and import by the aquaporin-like pentameric formate channel FocA is governed by interaction with pyruvate formate-lyase, the enzyme that generates formate. Formate is disproportionated by the reversible formate hydrogenlyase (FHL) complex, which has been isolated, allowing biochemical dissection of evolutionary parallels with complex I of the respiratory chain. A recently identified sulfido-ligand attached to Mo in the active site of formate dehydrogenases led to the proposal of a modified catalytic mechanism. Structural analysis of the homologous, H2-oxidizing Hyd-1 and Hyd-5 identified a novel proximal [4Fe-3S] cluster in the small subunit involved in conferring oxygen tolerance to the enzymes. Synthesis of Salmonella Typhimurium Hyd-5 occurs aerobically, which is novel for an enterobacterial Hyd. The O2-sensitive Hyd-2 enzyme has been shown to be reversible: it presumably acts as a conformational proton pump in the H2-oxidizing mode and is capable of coupling reverse electron transport to drive H2 release. The structural characterization of all the Hyp maturation proteins has given new impulse to studies on the biosynthesis of the Fe(CN)2CO moiety of the [NiFe] cofactor. It is synthesized on a Hyp-scaffold complex, mainly comprising HypC and HypD, before insertion into the apo-large subunit. Finally, clear evidence now exists indicating that Escherichia coli can mature Hyd enzymes differentially, depending on metal ion availability and the prevailing metabolic state. Notably, Hyd-3 of the FHL complex takes precedence over the H2-oxidizing enzymes.

  19. Disarming Fungal Pathogens: Bacillus safensis Inhibits Virulence Factor Production and Biofilm Formation by Cryptococcus neoformans and Candida albicans

    PubMed Central

    2017-01-01

    ABSTRACT Bacteria interact with each other in nature and often compete for limited nutrient and space resources. However, it is largely unknown whether and how bacteria also interact with human fungal pathogens naturally found in the environment. Here, we identified a soil bacterium, Bacillus safensis, which potently blocked several key Cryptococcus neoformans virulence factors, including formation of the antioxidant pigment melanin and production of the antiphagocytic polysaccharide capsule. The bacterium also inhibited de novo cryptococcal biofilm formation but had only modest inhibitory effects on already formed biofilms or planktonic cell growth. The inhibition of fungal melanization was dependent on direct cell contact and live bacteria. B. safensis also had anti-virulence factor activity against another major human-associated fungal pathogen, Candida albicans. Specifically, dual-species interaction studies revealed that the bacterium strongly inhibited C. albicans filamentation and biofilm formation. In particular, B. safensis physically attached to and degraded candidal filaments. Through genetic and phenotypic analyses, we demonstrated that bacterial chitinase activity against fungal cell wall chitin is a factor contributing to the antipathogen effect of B. safensis. PMID:28974618

  20. Mutations of RNA splicing factors in hematological malignancies.

    PubMed

    Shukla, Girish C; Singh, Jagjit

    2017-11-28

    Systematic large-scale cancer genomic studies have produced numerous significant findings. These studies have not only revealed new cancer-promoting genes, but they also have identified cancer-promoting functions of previously known "housekeeping" genes. These studies have identified numerous mutations in genes which play a fundamental role in nuclear precursor mRNA splicing. Somatic mutations and copy number variation in many of the splicing factors which participate in the formation of multiple spliceosomal complexes appear to play a role in many cancers and in particular in myelodysplastic syndromes (MDS). Mutated proteins seem to interfere with the recognition of the authentic splice sites (SS) leading to utilization of suboptimal alternative splicing sites generating aberrantly spliced mRNA isoforms. This short review is focusing on the function of the splice factors involved in the formation of splicing complexes and potential mechanisms which affect usage of the authentic splice site recognition. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Test item linguistic complexity and assessments for deaf students.

    PubMed

    Cawthon, Stephanie

    2011-01-01

    Linguistic complexity of test items is one test format element that has been studied in the context of struggling readers and their participation in paper-and-pencil tests. The present article presents findings from an exploratory study on the potential relationship between linguistic complexity and test performance for deaf readers. A total of 64 students completed 52 multiple-choice items, 32 in mathematics and 20 in reading. These items were coded for linguistic complexity components of vocabulary, syntax, and discourse. Mathematics items had higher linguistic complexity ratings than reading items, but there were no significant relationships between item linguistic complexity scores and student performance on the test items. The discussion addresses issues related to the subject area, student proficiency levels in the test content, factors to look for in determining a "linguistic complexity effect," and areas for further research in test item development and deaf students.

  2. Factors affecting THMs, HAAs and HNMs formation of Jin Lan Reservoir water exposed to chlorine and monochloramine.

    PubMed

    Hong, Huachang; Xiong, Yujing; Ruan, Mengyong; Liao, Fanglei; Lin, Hongjun; Liang, Yan

    2013-02-01

    The formations of THMs, HAAs, and HNMs from chlorination and chloramination of water from Jinlan Reservoir were investigated in this study. Results showed that monochloramine rather than chlorine generally resulted in lower concentration of DBPs, and the DBPs formation varied greatly as the treatment conditions changed. Specifically, the yields of THMs, HAAs and HNMs all increased with the high bromide level and high disinfectant dose both during chlorination and chloramination. The longer reaction time had a positive effect on the formation of THMs, HAAs and HNMs during chlorination and HNMs during chloramination. However, no time effect was observed on the formation of THMs and HAAs during chloramination. An increase in pH enhanced the levels of THMs and HNMs upon chlorination but reduced levels of HNMs upon chloramination. As for the THMs in chloramination and HAAs in chlorination and chloramination, no obvious pH effect was observed. The elevated temperature significantly increased the yields of THMs during chlorination and HNMs during chloramination, but has no effect on THMs and HAAs yields during chloramination. In the same temperature range, the formation of HAAs and HNMs in chlorination showed a first increasing and then a decreasing trend. In chloramination study, addition of nitrite markedly increased the formation of HNMs but had little impact on the formation of THMs and HAAs. While in chlorination study, the presence of high nitrite levels significantly reduced the yields of THMs, HAAs and HNMs. Range analysis revealed that the bromide and disinfectant levels were the major factors affecting THMs, HAAs and HNMs formation, in both chlorination and chloramination. Finally, comparisons of the speciation of mono-halogenated, di-halogenated, tri-halogenated HAAs and HNMs between chlorination and monochloramination were also conducted, and factors influencing the speciation pattern were identified. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Other factors to consider in the formation of chloropropandiol fatty esters in oil processes.

    PubMed

    Ramli, Muhamad Roddy; Siew, Wai Lin; Ibrahim, Nuzul Amri; Kuntom, Ainie; Abd Razak, Raznim Arni

    2015-01-01

    This paper examines the processing steps of extracting palm oil from fresh fruit bunches in a way that may impact on the formation of chloropropandiol fatty esters (3-MCPD esters), particularly during refining. Diacylglycerols (DAGs) do not appear to be a critical factor when crude palm oils are extracted from various qualities of fruit bunches. Highly hydrolysed oils, in spite of the high free fatty acid (FFA) contents, did not show exceptionally high DAGs, and the oils did not display a higher formation of 3-MCPD esters upon heat treatment. However, acidity measured in terms of pH appears to have a strong impact on 3-MCPD ester formation in the crude oil when heated at high temperatures. The differences in the extraction process of crude palm oil from current commercial processes and that from a modified experimental process showed clearly the effect of acidity of the oil on the formation of 3-MCPD esters. This paper concludes that the washing or dilution step in palm oil mills removes the acidity of the vegetative materials and that a well-optimised dilution/washing step in the extraction process will play an important role in reducing formation of 3-MCPD esters in crude palm oil upon further heat processing.

  4. Kinetics of the formation of a protein corona around nanoparticles.

    PubMed

    Zhdanov, Vladimir P; Cho, Nam-Joon

    2016-12-01

    Interaction of metal or oxide nanoparticles (NPs) with biological soft matter is one of the central phenomena in basic and applied biology-oriented nanoscience. Often, this interaction includes adsorption of suspended proteins on the NP surface, resulting in the formation of the protein corona around NPs. Structurally, the corona contains a "hard" monolayer shell directly contacting a NP and a more distant weakly associated "soft" shell. Chemically, the corona is typically composed of a mixture of distinct proteins. The corresponding experimental and theoretical studies have already clarified many aspects of the corona formation. The process is, however, complex, and its understanding is still incomplete. Herein, we present a kinetic mean-field model of the formation of the "hard" corona with emphasis on the role of (i) protein-diffusion limitations and (ii) interplay between competitive adsorption of distinct proteins and irreversible reconfiguration of their native structure. The former factor is demonstrated to be significant only in the very beginning of the corona formation. The latter factor is predicted to be more important. It may determine the composition of the corona on the time scales comparable or longer than a few hours. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Disulfide Bond Formation and ToxR Activity in Vibrio cholerae

    PubMed Central

    Fengler, Vera H. I.; Boritsch, Eva C.; Tutz, Sarah; Seper, Andrea; Ebner, Hanna; Roier, Sandro; Schild, Stefan; Reidl, Joachim

    2012-01-01

    Virulence factor production in Vibrio cholerae is complex, with ToxRS being an important part of the regulatory cascade. Additionally, ToxR is the transcriptional regulator for the genes encoding the major outer membrane porins OmpU and OmpT. ToxR is a transmembrane protein and contains two cysteine residues in the periplasmic domain. This study addresses the influence of the thiol-disulfide oxidoreductase system DsbAB, ToxR cysteine residues and ToxR/ToxS interaction on ToxR activity. The results show that porin production correlates with ToxR intrachain disulfide bond formation, which depends on DsbAB. In contrast, formation of ToxR intrachain or interchain disulfide bonds is dispensable for virulence factor production and in vivo colonization. This study further reveals that in the absence of ToxS, ToxR interchain disulfide bond formation is facilitated, whereat cysteinyl dependent homo- and oligomerization of ToxR is suppressed if ToxS is coexpressed. In summary, new insights into gene regulation by ToxR are presented, demonstrating a mechanism by which ToxR activity is linked to a DsbAB dependent intrachain disulfide bond formation. PMID:23144706

  6. Sorptive fractionation of organic matter and formation of organo-hydroxy-aluminum complexes during litter biodegradation in the presence of gibbsite

    Treesearch

    K. Heckman; A.S. Grandy; X. Gao; M. Keiluweit; K. Wickings; K. Carpenter; J. Chorover; C. Rasmussen

    2013-01-01

    Solid and aqueous phase Al species are recognized to affect organic matter (OM) stabilization in forest soils. However, little is known about the dynamics of formation, composition and dissolution of organo-Al hydroxide complexes in microbially-active soil systems, where plant litter is subject to microbial decomposition in close proximity to mineral weathering...

  7. Thymidine phosphorylase exerts complex effects on bone resorption and formation in myeloma.

    PubMed

    Liu, Huan; Liu, Zhiqiang; Du, Juan; He, Jin; Lin, Pei; Amini, Behrang; Starbuck, Michael W; Novane, Nora; Shah, Jatin J; Davis, Richard E; Hou, Jian; Gagel, Robert F; Yang, Jing

    2016-08-24

    Myelomatous bone disease is characterized by the development of lytic bone lesions and a concomitant reduction in bone formation, leading to chronic bone pain and fractures. To understand the underlying mechanism, we investigated the contribution of myeloma-expressed thymidine phosphorylase (TP) to bone lesions. In osteoblast progenitors, TP up-regulated the methylation of RUNX2 and osterix, leading to decreased bone formation. In osteoclast progenitors, TP up-regulated the methylation of IRF8 and thereby enhanced expression of NFATc1 (nuclear factor of activated T cells, cytoplasmic 1 protein), leading to increased bone resorption. TP reversibly catalyzes thymidine into thymine and 2-deoxy-d-ribose (2DDR). Myeloma-secreted 2DDR bound to integrin αVβ3/α5β1 in the progenitors, activated PI3K (phosphoinositide 3-kinase)/Akt signaling, and increased DNMT3A (DNA methyltransferase 3A) expression, resulting in hypermethylation of RUNX2, osterix, and IRF8 This study elucidates an important mechanism for myeloma-induced bone lesions, suggesting that targeting TP may be a viable approach to healing resorbed bone in patients. Because TP overexpression is common in bone-metastatic tumors, our findings could have additional mechanistic implications. Copyright © 2016, American Association for the Advancement of Science.

  8. Capturing cooperative interactions with the PSI-MI format

    PubMed Central

    Van Roey, Kim; Orchard, Sandra; Kerrien, Samuel; Dumousseau, Marine; Ricard-Blum, Sylvie; Hermjakob, Henning; Gibson, Toby J.

    2013-01-01

    The complex biological processes that control cellular function are mediated by intricate networks of molecular interactions. Accumulating evidence indicates that these interactions are often interdependent, thus acting cooperatively. Cooperative interactions are prevalent in and indispensible for reliable and robust control of cell regulation, as they underlie the conditional decision-making capability of large regulatory complexes. Despite an increased focus on experimental elucidation of the molecular details of cooperative binding events, as evidenced by their growing occurrence in literature, they are currently lacking from the main bioinformatics resources. One of the contributing factors to this deficiency is the lack of a computer-readable standard representation and exchange format for cooperative interaction data. To tackle this shortcoming, we added functionality to the widely used PSI-MI interchange format for molecular interaction data by defining new controlled vocabulary terms that allow annotation of different aspects of cooperativity without making structural changes to the underlying XML schema. As a result, we are able to capture cooperative interaction data in a structured format that is backward compatible with PSI-MI–based data and applications. This will facilitate the storage, exchange and analysis of cooperative interaction data, which in turn will advance experimental research on this fundamental principle in biology. Database URL: http://psi-mi-cooperativeinteractions.embl.de/ PMID:24067240

  9. Evaluation of environmental and nutritional factors and sua gene on in vitro biofilm formation of Streptococcus uberis isolates.

    PubMed

    Moliva, Melina Vanesa; Cerioli, Florencia; Reinoso, Elina Beatriz

    2017-06-01

    The pathogenesis of Streptococcus uberis is attributed to a combination of extracellular factors and properties such as adherence and biofilm formation. The aim of this work was to evaluate the influence of different factors, additives and bovine milk compounds on S. uberis biofilm formation, as the presence of the sua gene by PCR. Additionally, extracellular DNA and the effect of DNaseI were evaluated in the biofilms yielded. Optimal biofilm development was observed when the pH was adjusted to 7.0 and 37 °C. Additives as glucose and lactose reduced biofilm formation as bovine milk compounds tested. PCR assay showed that not all the isolates yielded sua gene. Extrachromosomal ADN was found in cell-free supernatants, suggesting that DNA released spontaneously to the medium. The results contribute to a better understanding of the factors involved in biofilm production of this important pathogen associated with mastitis in order to promote the design of new therapeutic approaches. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Global Analysis of Yeast Endosomal Transport Identifies the Vps55/68 Sorting Complex

    PubMed Central

    Schluter, Cayetana; Lam, Karen K.Y.; Brumm, Jochen; Wu, Bella W.; Saunders, Matthew; Stevens, Tom H.

    2008-01-01

    Endosomal transport is critical for cellular processes ranging from receptor down-regulation and retroviral budding to the immune response. A full understanding of endosome sorting requires a comprehensive picture of the multiprotein complexes that orchestrate vesicle formation and fusion. Here, we use unsupervised, large-scale phenotypic analysis and a novel computational approach for the global identification of endosomal transport factors. This technique effectively identifies components of known and novel protein assemblies. We report the characterization of a previously undescribed endosome sorting complex that contains two well-conserved proteins with four predicted membrane-spanning domains. Vps55p and Vps68p form a complex that acts with or downstream of ESCRT function to regulate endosomal trafficking. Loss of Vps68p disrupts recycling to the TGN as well as onward trafficking to the vacuole without preventing the formation of lumenal vesicles within the MVB. Our results suggest the Vps55/68 complex mediates a novel, conserved step in the endosomal maturation process. PMID:18216282

  11. Frataxin Accelerates [2Fe-2S] Cluster Formation on the Human Fe–S Assembly Complex

    PubMed Central

    Fox, Nicholas G.; Das, Deepika; Chakrabarti, Mrinmoy; Lindahl, Paul A.; Barondeau, David P.

    2015-01-01

    Iron–sulfur (Fe–S) clusters function as protein cofactors for a wide variety of critical cellular reactions. In human mitochondria, a core Fe–S assembly complex [called SDUF and composed of NFS1, ISD11, ISCU2, and frataxin (FXN) proteins] synthesizes Fe–S clusters from iron, cysteine sulfur, and reducing equivalents and then transfers these intact clusters to target proteins. In vitro assays have relied on reducing the complexity of this complicated Fe–S assembly process by using surrogate electron donor molecules and monitoring simplified reactions. Recent studies have concluded that FXN promotes the synthesis of [4Fe-4S] clusters on the mammalian Fe–S assembly complex. Here the kinetics of Fe–S synthesis reactions were determined using different electron donation systems and by monitoring the products with circular dichroism and absorbance spectroscopies. We discovered that common surrogate electron donor molecules intercepted Fe–S cluster intermediates and formed high-molecular weight species (HMWS). The HMWS are associated with iron, sulfide, and thiol-containing proteins and have properties of a heterogeneous solubilized mineral with spectroscopic properties remarkably reminiscent of those of [4Fe-4S] clusters. In contrast, reactions using physiological reagents revealed that FXN accelerates the formation of [2Fe-2S] clusters rather than [4Fe-4S] clusters as previously reported. In the preceding paper [Fox, N. G., et al. (2015) Biochemistry 54, DOI: 10.1021/bi5014485], [2Fe-2S] intermediates on the SDUF complex were shown to readily transfer to uncomplexed ISCU2 or apo acceptor proteins, depending on the reaction conditions. Our results indicate that FXN accelerates a rate-limiting sulfur transfer step in the synthesis of [2Fe-2S] clusters on the human Fe–S assembly complex. PMID:26016518

  12. Frataxin Accelerates [2Fe-2S] Cluster Formation on the Human Fe-S Assembly Complex.

    PubMed

    Fox, Nicholas G; Das, Deepika; Chakrabarti, Mrinmoy; Lindahl, Paul A; Barondeau, David P

    2015-06-30

    Iron-sulfur (Fe-S) clusters function as protein cofactors for a wide variety of critical cellular reactions. In human mitochondria, a core Fe-S assembly complex [called SDUF and composed of NFS1, ISD11, ISCU2, and frataxin (FXN) proteins] synthesizes Fe-S clusters from iron, cysteine sulfur, and reducing equivalents and then transfers these intact clusters to target proteins. In vitro assays have relied on reducing the complexity of this complicated Fe-S assembly process by using surrogate electron donor molecules and monitoring simplified reactions. Recent studies have concluded that FXN promotes the synthesis of [4Fe-4S] clusters on the mammalian Fe-S assembly complex. Here the kinetics of Fe-S synthesis reactions were determined using different electron donation systems and by monitoring the products with circular dichroism and absorbance spectroscopies. We discovered that common surrogate electron donor molecules intercepted Fe-S cluster intermediates and formed high-molecular weight species (HMWS). The HMWS are associated with iron, sulfide, and thiol-containing proteins and have properties of a heterogeneous solubilized mineral with spectroscopic properties remarkably reminiscent of those of [4Fe-4S] clusters. In contrast, reactions using physiological reagents revealed that FXN accelerates the formation of [2Fe-2S] clusters rather than [4Fe-4S] clusters as previously reported. In the preceding paper [Fox, N. G., et al. (2015) Biochemistry 54, DOI: 10.1021/bi5014485], [2Fe-2S] intermediates on the SDUF complex were shown to readily transfer to uncomplexed ISCU2 or apo acceptor proteins, depending on the reaction conditions. Our results indicate that FXN accelerates a rate-limiting sulfur transfer step in the synthesis of [2Fe-2S] clusters on the human Fe-S assembly complex.

  13. PF4/heparin-antibody complex induces monocyte tissue factor expression and release of tissue factor positive microparticles by activation of FcγRI

    PubMed Central

    Glover, Sam L.; Jonas, William; McEachron, Troy; Pawlinski, Rafal; Arepally, Gowthami M.; Key, Nigel S.; Mackman, Nigel

    2012-01-01

    Heparin-induced thrombocytopenia (HIT) is a potentially devastating form of drug-induced thrombocytopenia that occurs in patients receiving heparin for prevention or treatment of thrombosis. Patients with HIT develop autoantibodies to the platelet factor 4 (PF4)/heparin complex, which is termed the HIT Ab complex. Despite a decrease in the platelet count, the most feared complication of HIT is thrombosis. The mechanism of thrombosis in HIT remains poorly understood. We investigated the effects of the HIT Ab complex on tissue factor (TF) expression and release of TF-positive microparticles in peripheral blood mononuclear cells and monocytes. To model these effects ex vivo, we used a murine mAb specific for the PF4/heparin complex (KKO), as well as plasma from patients with HIT. We found that the HIT Ab complex induced TF expression in monocytes and the release of TF-positive microparticles. Further, we found that induction of TF is mediated via engagement of the FcγRI receptor and activation of the MEK1-ERK1/2 signaling pathway. Our data suggest that monocyte TF may contribute to the development of thrombosis in patients with HIT. PMID:22394597

  14. Nonadiabatic one-electron transfer mechanism for the O-O bond formation in the oxygen-evolving complex of photosystem II

    NASA Astrophysics Data System (ADS)

    Shoji, Mitsuo; Isobe, Hiroshi; Shigeta, Yasuteru; Nakajima, Takahito; Yamaguchi, Kizashi

    2018-04-01

    The reaction mechanism of the O2 formation in the S4 state of the oxygen-evolving complex of photosystem II was clarified at the quantum mechanics/molecular mechanics (QM/MM) level. After the Yz (Y161) oxidation and the following proton transfer in the S3 state, five reaction steps are required to produce the molecular dioxygen. The highest barrier step is the first proton transfer reaction (0 → 1). The following reactions involving electron transfers were precisely analyzed in terms of their energies, structures and spin densities. We found that the one-electron transfer from the Mn4Ca cluster to Y161 triggers the O-O sigma bond formation.

  15. Towards a framework of human factors certification of complex human-machine systems

    NASA Technical Reports Server (NTRS)

    Bukasa, Birgit

    1994-01-01

    As far as total automation is not realized, the combination of technical and social components in man-machine systems demands not only contributions from engineers but at least to an equal extent from behavioral scientists. This has been neglected far too long. The psychological, social and cultural aspects of technological innovations were almost totally overlooked. Yet, along with expected safety improvements the institutionalization of human factors is on the way. The introduction of human factors certification of complex man-machine systems will be a milestone in this process.

  16. Vascular lumen formation.

    PubMed

    Lammert, Eckhard; Axnick, Jennifer

    2012-04-01

    The vascular system developed early in evolution. It is required in large multicellular organisms for the transport of nutrients, oxygen, and waste products to and from tissues. The vascular system is composed of hollow tubes, which have a high level of complexity in vertebrates. Vasculogenesis describes the de novo formation of blood vessels, e.g., aorta formation in vertebrate embryogenesis. In contrast, angiogenesis is the formation of blood vessels from preexisting ones, e.g., sprouting of intersomitic blood vessels from the aorta. Importantly, the lumen of all blood vessels in vertebrates is lined and formed by endothelial cells. In both vasculogenesis and angiogenesis, lumen formation takes place in a cord of endothelial cells. It involves a complex molecular mechanism composed of endothelial cell repulsion at the cell-cell contacts within the endothelial cell cords, junctional rearrangement, and endothelial cell shape change. As the vascular system also participates in the course of many diseases, such as cancer, stroke, and myocardial infarction, it is important to understand and make use of the molecular mechanisms of blood vessel formation to better understand and manipulate the pathomechanisms involved.

  17. Effects of ultrasonic treatment on amylose-lipid complex formation and properties of sweet potato starch-based films.

    PubMed

    Liu, Pengfei; Wang, Rui; Kang, Xuemin; Cui, Bo; Yu, Bin

    2018-06-01

    To investigate the effect of ultrasonic treatment on the properties of sweet potato starch and sweet potato starch-based films, the complexing index, thermograms and diffractograms of the sweet potato starch-lauric acid composite were tested, and light transmission, microstructure, and mechanical and moisture barrier properties of the films were measured. The results indicated that the low power density ultrasound was beneficial to the formation of an inclusion complex. In thermograms, the gelatinization enthalpies of the ultrasonically treated starches were lower than those of the untreated sample. With the ultrasonic amplitude increased from 40% to 70%, the melting enthalpy (ΔH) of the inclusion complex gradually decreased. X-ray diffraction revealed that the diffraction intensity of the untreated samples was weaker than that of the ultrasonically treated samples. When the ultrasonic amplitude was above 40%, the diffraction intensity and relative crystallinity of inclusion complex gradually decreased. The scanning electronic microscope showed that the surface of the composite films became smooth after being treated by ultrasonication. Ultrasonication led to a reduction in film surface roughness under atomic force microscopy analysis. The films with ultrasonic treatment exhibited higher light transmission, lower elongation at break, higher tensile strength and better moisture barrier property than those without ultrasonic treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Bow shock formation in a complex plasma.

    PubMed

    Saitou, Y; Nakamura, Y; Kamimura, T; Ishihara, O

    2012-02-10

    A bow shock is observed in a two-dimensional supersonic flow of charged microparticles in a complex plasma. A thin conducting needle is used to make a potential barrier as an obstacle for the particle flow in the complex plasma. The flow is generated and the flow velocity is controlled by changing a tilt angle of the device under the gravitational force. A void, microparticle-free region, is formed around the potential barrier surrounding the obstacle. The flow is bent around the leading edge of the void and forms an arcuate structure when the flow is supersonic. The structure is characterized by the bow shock as confirmed by a polytropic hydrodynamic theory as well as numerical simulation.

  19. Solvation-induced σ-complex structure formation in the gas phase: a revisit to the infrared spectroscopy of [C6H6-(CH3OH)2]+.

    PubMed

    Mizuse, Kenta; Suzuki, Yuta; Mikami, Naohiko; Fujii, Asuka

    2011-10-20

    Structures of the [C(6)H(6)-(CH(3)OH)(2)](+) cluster cation are investigated with infrared (IR) spectroscopy. While the noncovalent type structure has been confirmed for the n = 1 cluster of [C(6)H(6)-(CH(3)OH)(n)](+), only contradictory interpretations have been given for the spectra of n = 2, in which significant changes have been observed with the Ar tagging. In the present study, we revisit IR spectroscopy of the n = 2 cluster from the viewpoint of the σ-complex structure, which includes a covalent bond formation between the benzene and methanol moieties. The observed spectral range is extended to the lower-frequency region, and the spectrum is measured with and without Ar and N(2) tagging. A strongly hydrogen-bonded OH stretch band, which is characteristic to the σ-complex structure, is newly found with the tagging. The remarkable spectral changes with the tagging are interpreted by the competition between the σ-complex and noncovalent complex structures in the [C(6)H(6)-(CH(3)OH)(2)](+) system. This result shows that the microsolvation only with one methanol molecule can induce the σ-complex structure formation.

  20. Evidence of formation of site-selective inclusion complexation between beta-cyclodextrin and poly(ethylene oxide)-block-poly(propylene oxide)- block-poly(ethylene oxide) copolymers.

    PubMed

    Tsai, Chi-Chun; Zhang, Wen-Bin; Wang, Chien-Lung; Van Horn, Ryan M; Graham, Matthew J; Huang, Jing; Chen, Yongming; Guo, Mingming; Cheng, Stephen Z D

    2010-05-28

    A series of inclusion complexes of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-b-PPO-b-PEO) with beta-cyclodextrin (beta-CD) was prepared. Their formation, structure, and dynamics were investigated by solution two-dimensional rotating-frame Overhauser effect spectroscopy (2D ROESY) and one-dimensional (1D) and 2D solid-state (13)C NMR. The inclusion complexes between the PEO-b-PPO-b-PEO copolymers and the beta-CDs were formed in aqueous solution and detected by 2D ROESY. The high efficiency of cross polarization and spin diffusion experiments in (13)C solid-state NMR showed that the mobility of the PPO blocks dramatically decreases after beta-CD complexation, indicating that they are selectively incorporated onto the PPO blocks. The hydrophobic cavities of beta-CD restrict the PPO block mobility, which is evidence of the formation of inclusion complexes in the solid state. The 2D wide-line separation NMR experiments suggested that beta-CDs only thread onto the PPO blocks while forming the inclusion complexes. The stoichiometry of inclusion complexes was studied using (1)H NMR, and a 3:1 (PO unit to beta-CD) was found for all inclusion complexes, which indicated that the number of threaded beta-CDs was only dependent on the molecular weight of the PPO blocks. 1D wide angle x-ray diffraction studies demonstrated that the beta-CD in the inclusion complex formed a channel-like structure that is different from the pure beta-CD crystal structure.