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Sample records for oligomerization domain-2 play

  1. Activation of nucleotide oligomerization domain 2 (NOD2 by human cytomegalovirus initiates innate immune responses and restricts virus replication.

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    Arun Kapoor

    Full Text Available Nucleotide-binding oligomerization domain 2 (NOD2 is an important innate immune sensor of bacterial pathogens. Its induction results in activation of the classic NF-κB pathway and alternative pathways including type I IFN and autophagy. Although the importance of NOD2 in recognizing RNA viruses has recently been identified, its role in sensing DNA viruses has not been studied. We report that infection with human cytomegalovirus (HCMV results in significant induction of NOD2 expression, beginning as early as 2 hours post infection and increasing steadily 24 hours post infection and afterwards. Infection with human herpesvirus 1 and 2 does not induce NOD2 expression. While the HCMV-encoded glycoprotein B is not required for NOD2 induction, a replication competent virion is necessary. Lentivirus-based NOD2 knockdown in human foreskin fibroblasts (HFFs and U373 glioma cells leads to enhanced HCMV replication along with decreased levels of interferon beta (IFN-β and the pro-inflammatory cytokine, IL8. NOD2 induction in HCMV-infected cells activates downstream NF-κB and interferon pathways supported by reduced nuclear localization of NF-κB and pIRF3 in NOD2 knockdown HFFs. Stable overexpression of NOD2 in HFFs restricts HCMV replication in association with increased levels of IFN-β and IL8. Similarly, transient overexpression of NOD2 in U373 cells or its downstream kinase, RIPK2, results in decreased HCMV replication and enhanced cytokine responses. However, overexpression of a mutant NOD2, 3020insC, associated with severe Crohn's disease, results in enhanced HCMV replication and decreased levels of IFN-β in U373 cells. These results show for the first time that NOD2 plays a significant role in HCMV replication and may provide a model for studies of HCMV recognition by the host cell and HCMV colitis in Crohn's disease.

  2. Species-specific engagement of human nucleotide oligomerization domain 2 (NOD)2 and Toll-like receptor (TLR) signalling upon intracellular bacterial infection

    DEFF Research Database (Denmark)

    Salem, M; Seidelin, J B; Eickhardt-Dalbøge, Steffen Robert

    2015-01-01

    Recognition of bacterial peptidoglycan-derived muramyl-dipeptide (MDP) by nucleotide oligomerization domain 2 (NOD2) induces crucial innate immune responses. Most bacteria carry the N-acetylated form of MDP (A-MDP) in their cell membranes, whereas N-glycolyl MDP (G-MDP) is typical for mycobacteri...

  3. Nucleotide-oligomerization-domain-2 affects commensal gut microbiota composition and intracerebral immunopathology in acute Toxoplasma gondii induced murine ileitis.

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    Markus M Heimesaat

    Full Text Available Within one week following peroral high dose infection with Toxoplasma (T. gondii, susceptible mice develop non-selflimiting acute ileitis due to an underlying Th1-type immunopathology. The role of the innate immune receptor nucleotide-oligomerization-domain-2 (NOD2 in mediating potential extra-intestinal inflammatory sequelae including the brain, however, has not been investigated so far.Following peroral infection with 100 cysts of T. gondii strain ME49, NOD2-/- mice displayed more severe ileitis and higher small intestinal parasitic loads as compared to wildtype (WT mice. However, systemic (i.e. splenic levels of pro-inflammatory cytokines such as TNF-α and IFN-γ were lower in NOD2-/- mice versus WT controls at day 7 p.i. Given that the immunopathological outcome might be influenced by the intestinal microbiota composition, which is shaped by NOD2, we performed a quantitative survey of main intestinal bacterial groups by 16S rRNA analysis. Interestingly, Bifidobacteria were virtually absent in NOD2-/- but not WT mice, whereas differences in remaining bacterial species were rather subtle. Interestingly, more distinct intestinal inflammation was accompanied by higher bacterial translocation rates to extra-intestinal tissue sites such as liver, spleen, and kidneys in T. gondii infected NOD2-/- mice. Strikingly, intracerebral inflammatory foci could be observed as early as seven days following T. gondii infection irrespective of the genotype of animals, whereas NOD2-/- mice exhibited higher intracerebral parasitic loads, higher F4/80 positive macrophage and microglia numbers as well as higher IFN-γ mRNA expression levels as compared to WT control animals.NOD2 signaling is involved in protection of mice from T. gondii induced acute ileitis. The parasite-induced Th1-type immunopathology at intestinal as well as extra-intestinal sites including the brain is modulated in a NOD2-dependent manner.

  4. Retinoic acid-induced gene-I (RIG-I) associates with nucleotide-binding oligomerization domain-2 (NOD2) to negatively regulate inflammatory signaling.

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    Morosky, Stefanie A; Zhu, Jianzhong; Mukherjee, Amitava; Sarkar, Saumendra N; Coyne, Carolyn B

    2011-08-12

    Cytoplasmic caspase recruiting domain (CARD)-containing molecules often function in the induction of potent antimicrobial responses in order to protect mammalian cells from invading pathogens. Retinoic acid-induced gene-I (RIG-I) and nucleotide binding oligomerization domain 2 (NOD2) serve as key factors in the detection of viral and bacterial pathogens, and in the subsequent initiation of innate immune signals to combat infection. RIG-I and NOD2 share striking similarities in their cellular localization, both localize to membrane ruffles in non-polarized epithelial cells and both exhibit a close association with the junctional complex of polarized epithelia. Here we show that RIG-I and NOD2 not only colocalize to cellular ruffles and cell-cell junctions, but that they also form a direct interaction that is mediated by the CARDs of RIG-I and multiple regions of NOD2. Moreover, we show that RIG-I negatively regulates ligand-induced nuclear factor-κB (NF-κB) signaling mediated by NOD2, and that NOD2 negatively regulates type I interferon induction by RIG-I. We also show that the three main Crohn disease-associated mutants of NOD2 (1007fs, R702W, G908R) form an interaction with RIG-I and negatively regulate its signaling to a greater extent than wild-type NOD2. Our results show that in addition to their role in innate immune recognition, RIG-I and NOD2 form a direct interaction at actin-enriched sites within cells and suggest that this interaction may impact RIG-I- and NOD2-dependent innate immune signaling.

  5. Identification of MDP (muramyl dipeptide)-binding key domains in NOD2 (nucleotide-binding and oligomerization domain-2) receptor of Labeo rohita.

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    Maharana, Jitendra; Swain, Banikalyan; Sahoo, Bikash R; Dikhit, Manas R; Basu, Madhubanti; Mahapatra, Abhijit S; Jayasankar, Pallipuram; Samanta, Mrinal

    2013-08-01

    In lower eukaryotes-like fish, innate immunity contributed by various pattern recognition receptor (PRR) plays an essential role in protection against diseases. Nucleotide-binding and oligomerization domain (NOD)-2 is a cytoplasmic PRR that recognizes MDP (muramyl dipeptide) of the Gram positive and Gram negative bacteria as ligand and activates signalling to induce innate immunity. Hypothesizing a similar NOD2 signalling pathway of higher eukaryotes, the peripheral blood leucocytes (PBLs) of rohu (Labeo rohita) was stimulated with MDP. The data of quantitative real-time PCR (qRT-PCR) revealed MDP-mediated inductive expression of NOD2 and its down-stream molecule RICK/RIP2 (receptor-interacting serine-threonine protein kinase-2). This observation suggested the existence of MDP-binding sites in rohu NOD2 (rNOD2). To investigate it, 3D model of ligand-binding leucine-rich repeat (LRR) region of rNOD2 (rNOD2-LRR) was constructed following ab initio and threading approaches in I-TASSER web server. Structural refinement of the model was performed by energy minimization, and MD (molecular dynamics) simulation was performed in GROMACS (Groningen Machine for Chemical Simulations). The refined model of rNOD2-LRR was validated through SAVES, ProSA, ProQ, WHAT IF and MolProbity servers, and molecular docking with MDP was carried out in GOLD 4.1. The result of docking identified LRR3-7 comprising Lys820, Phe821, Asn822, Arg847, Gly849, Trp877, Trp901 and Trp931 as MDP-binding critical amino acids in rNOD2. This is the first study in fish to provide an insight into the 3D structure of NOD2-LRR region and its important motifs that are expected to be engaged in MDP binding and innate immunity.

  6. Microbiota Composition and Immune Responses During Campylobacter Jejuni Infection in Conventionally Colonized IL-10–/– Mice Lacking Nucleotide Oligomerization Domain 2

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    Heimesaat, Markus M.; Grundmann, Ursula; Alutis, Marie E.; Fischer, André; Bereswill, Stefan

    2016-01-01

    Host immune responses are pivotal for combating enteropathogenic infections. We here assessed the impact of the innate receptor nucleotide oligomerization domain protein 2 (NOD2) in murine Campylobacter jejuni-infection. Conventionally colonized IL-10–/– mice lacking NOD2 and IL-10–/– controls were perorally challenged with C. jejuni strain 81-176 and displayed comparable pathogenic colonization of intestines until day 14 postinfection (p.i.). Whereas overall intestinal microbiota compositions were comparable in naive mice, NOD2–/– IL-10–/– mice exhibited less fecal bifidobacteria and lactobacilli than IL-10–/– counterparts after infection. Interestingly, NOD2–/– IL-10–/– mice were clinically more compromised during the early phase of infection, whereas, conversely, IL-10–/– animals exhibited more frequently bloody feces lateron. While colonic apoptotic cell and T lymphocyte numbers were comparable in either C. jejuni-infected mice, B lymphocytes were lower in the colon of infected NOD2–/– IL-10–/– mice versus controls. At day 14 p.i., colonic TNF and IL-23p19 mRNA levels were upregulated in NOD2–/– IL-10–/– mice only. Translocation rates of intestinal commensals to mesenteric lymphnodes and extra-intestinal compartments including liver and kidney were comparable, whereas viable bacteria were more frequently detected in spleens derived from IL-10–/– as compared to NOD2–/– IL-10–/– mice. In conclusion, NOD2 is involved during C. jejuni infection in conventionally colonized IL-10–/– mice in a time-dependent manner.

  7. Toll-like receptor 2 and nucleotide-binding oligomerization domain-2 play divergent roles in the recognition of gut-derived lactobacilli and bifidobacteria in dendritic cells

    DEFF Research Database (Denmark)

    Zeuthen, Louise; Fink, Lisbeth Nielsen; Frøkiær, Hanne

    2008-01-01

    -marrow-derived DC lacking NOD2 produce higher levels of interleukin-10 (IL-10) and reduced levels of IL-12 and tumour necrosis factor-[alpha] (TNF-[alpha]) in response to LAB. This indicates that peptidoglycan is partly responsible for the T helper type 1 skewing effect of certain LAB. Dendritic cells that are TLR2......-/- produce less IL-12 and TNF-[alpha] and more IL-10 in response to some strains of lactobacilli, while they produce more IL-12 and less IL-10 in response to bifidobacteria. The same tendency was found in human monocyte-derived DC. We have previously reported that the weak IL-12-inducing and TNF......-[alpha]-inducing bifidobacteria inhibit the T helper type 1 skewing effect induced by strong immunostimulatory lactobacilli. Here we show that this immunoinhibitory effect of bifidobacteria is dependent on TLR2 and independent of NOD2. Moreover, independently of the cytokine pattern induced by intact LAB, cell wall fractions...

  8. Uncovering the Mechanism of Forkhead-Associated Domain-Mediated TIFA Oligomerization That Plays a Central Role in Immune Responses.

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    Weng, Jui-Hung; Hsieh, Yin-Cheng; Huang, Chia-Chi Flora; Wei, Tong-You Wade; Lim, Liang-Hin; Chen, Yu-Hou; Ho, Meng-Ru; Wang, Iren; Huang, Kai-Fa; Chen, Chun-Jung; Tsai, Ming-Daw

    2015-10-13

    Forkhead-associated (FHA) domain is the only signaling domain that recognizes phosphothreonine (pThr) specifically. TRAF-interacting protein with an FHA domain (TIFA) was shown to be involved in immune responses by binding with TRAF2 and TRAF6. We recently reported that TIFA is a dimer in solution and that, upon stimulation by TNF-α, TIFA is phosphorylated at Thr9, which triggers TIFA oligomerization via pThr9-FHA domain binding and activates nuclear factor κB (NF-κB). However, the structural mechanism for the functionally important TIFA oligomerization remains to be established. While FHA domain-pThr binding is known to mediate protein dimerization, its role in oligomerization has not been demonstrated at the structural level. Here we report the crystal structures of TIFA (residues 1-150, with the unstructured C-terminal tail truncated) and its complex with the N-terminal pThr9 peptide (residues 1-15), which show unique features in the FHA structure (intrinsic dimer and extra β-strand) and in its interaction with the pThr peptide (with residues preceding rather than following pThr). These structural features support previous and additional functional analyses. Furthermore, the structure of the complex suggests that the pThr9-FHA domain interaction can occur only between different sets of dimers rather than between the two protomers within a dimer, providing the structural mechanism for TIFA oligomerization. Our results uncover the mechanism of FHA domain-mediated oligomerization in a key step of immune responses and expand the paradigm of FHA domain structure and function.

  9. Isoleucine at position 150 of Cyt2Aa toxin from Bacillus thuringiensis plays an important role during membrane binding and oligomerization

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    Wanwarang Pathaichindachote

    2013-03-01

    Full Text Available Cyt2Aa2 is a mosquito larvicidal and cytolytic toxin producedby Bacillus thuringiensis subsp. darmstadiensis. The toxin becomesinactive when isoleucine at position 150 was replacedby alanine. To investigate the functional role of this position,Ile150 was substituted with Leu, Phe, Glu and Lys. All mutantproteins were produced at high level, solubilized in carbonatebuffer and yielded protease activated product similar to thoseof the wild type. Intrinsic fluorescence spectra analysis suggestedthat these mutants retain similar folding to the wildtype. However, mosquito larvicidal and hemolytic activitiesdramatically decreased for the I150K and were completelyabolished for I150A and I150F mutants. Membrane bindingand oligomerization assays demonstrated that only I150E andI150L could bind and form oligomers on lipid membrane similarto that of the wild type. Our results suggest that amino acidat position 150 plays an important role during membranebinding and oligomerization of Cyt2Aa2 toxin. [BMB Reports2013; 46(3: 175-180

  10. Nucleotide-Binding Oligomerization Domain-1 and -2 Play No Role in Controlling Brucella abortus Infection in Mice

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    Fernanda S. Oliveira

    2012-01-01

    Full Text Available Nucleotide-binding oligomerization domain proteins (NODs are modular cytoplasmic proteins implicated in the recognition of peptidoglycan-derived molecules. Further, several in vivo studies have demonstrated a role for Nod1 and Nod2 in host defense against bacterial pathogens. Here, we demonstrated that macrophages from NOD1-, NOD2-, and Rip2-deficient mice produced lower levels of TNF-α following infection with live Brucella abortus compared to wild-type mice. Similar reduction on cytokine synthesis was not observed for IL-12 and IL-6. However, NOD1, NOD2, and Rip2 knockout mice were no more susceptible to infection with virulent B. abortus than wild-type mice. Additionally, spleen cells from NOD1-, NOD2-, and Rip2-deficient mice showed unaltered production of IFN-γ compared to C57BL/6 mice. Taken together, this study demonstrates that NOD1, NOD2 and Rip2 are dispensable for the control of B. abortus during in vivo infection.

  11. The Oligomerization Domain of VP3, the Scaffolding Protein of Infectious Bursal Disease Virus, Plays a Critical Role in Capsid Assembly

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    Maraver, Antonio; Oña, Ana; Abaitua, Fernando; González, Dolores; Clemente, Roberto; Ruiz-Díaz, Jose A.; Castón, Jose R.; Pazos, Florencio; Rodriguez, Jose F.

    2003-01-01

    Infectious bursal disease virus (IBDV) capsids are formed by a single protein layer containing three polypeptides, pVP2, VP2, and VP3. Here, we show that the VP3 protein synthesized in insect cells, either after expression of the complete polyprotein or from a VP3 gene construct, is proteolytically degraded, leading to the accumulation of product lacking the 13 C-terminal residues. This finding led to identification of the VP3 oligomerization domain within a 24-amino-acid stretch near the C-terminal end of the polypeptide, partially overlapping the VP1 binding domain. Inactivation of the VP3 oligomerization domain, by either proteolysis or deletion of the polyprotein gene, abolishes viruslike particle formation. Formation of VP3-VP1 complexes in cells infected with a dual recombinant baculovirus simultaneously expressing the polyprotein and VP1 prevented VP3 proteolysis and led to efficient virus-like particle formation in insect cells. PMID:12743301

  12. Domain 2: Sport Safety and Injury Prevention

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    Gurchiek, Larry; Mokha, Monique Butcher

    2004-01-01

    Most coaches recognize the importance of creating a safe environment and preventing injuries of their athletes. Domain 2 is dedicated to this important aspect of coaching, and outlines specific areas within safety and injury prevention that coaches should address. Domain 2 sets the standards for facility, equipment, and environmental safety…

  13. Deteksi Mutasi Gen Nukleotide-Binding Oligomerization Domain 2 (NOD) 2) Pada Penderita Periodontitis

    OpenAIRE

    2011-01-01

    Periodontitis adalah penyakit inflamasi kronis yang menyebabkan kerusakan jaringan penyangga gigi. Patogenesis terjadinya multifaktorial yang disebabkan oleh bakteri periodontopatogen yang melekat pada gigi yang disebut sebagai plak. Incidence of periodontitis in Indonesia was high enough, this disease is a major cause of tooth loss for people in age group 35 years and above. The various studies have reported that many occur in are common periodontitis at young age wich suggest taht g...

  14. Oligomerization in health and disease

    CERN Document Server

    Giraldo, Jesus

    2013-01-01

    This special volume of Progress in Molecular Biology and Translational Science focuses on oligomerization in health and disease. Contributions from leading authorities Informs and updates on all the latest developments in the field.

  15. Biophysical characterization of GPCR oligomerization

    DEFF Research Database (Denmark)

    Mathiasen, Signe

    a quantitative characterization of GPCR oligomerization. The assay provided the first quantification of the association energy of the β2 Adrenergic Receptor (β2AR), a prototypical GPCR. Furthermore we directly observed the time-dependent dimerization of β2AR and Cannabinoid receptor 1 at the single molecule......The biophysical characterization of the fundamental molecular mechanisms behind G-protein coupled receptors (GPCRs) oligomerization is proposed to be paramount for understanding the pharmacological consequence of receptor self-association. Here we developed an in vitro assay that allowed...

  16. Oligomerization of Uukuniemi virus nucleocapsid protein

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    Katz Anna

    2010-08-01

    Full Text Available Abstract Background Uukuniemi virus (UUKV belongs to the Phlebovirus genus in the family Bunyaviridae. As a non-pathogenic virus for humans UUKV has served as a safe model bunyavirus in a number of studies addressing fundamental questions such as organization and regulation of viral genes, genome replication, structure and assembly. The present study is focused on the oligomerization of the UUKV nucleocapsid (N protein, which plays an important role in several steps of virus replication. The aim was to locate the domains involved in the N protein oligomerization and study the process in detail. Results A set of experiments concentrating on the N- and C-termini of the protein was performed, first by completely or partially deleting putative N-N-interaction domains and then by introducing point mutations of amino acid residues. Mutagenesis strategy was based on the computer modeling of secondary and tertiary structure of the N protein. The N protein mutants were studied in chemical cross-linking, immunofluorescence, mammalian two-hybrid, minigenome, and virus-like particle-forming assays. The data showed that the oligomerization ability of UUKV-N protein depends on the presence of intact α-helices on both termini of the N protein molecule and that a specific structure in the N-terminal region plays a crucial role in the N-N interaction(s. This structure is formed by two α-helices, rich in amino acid residues with aromatic (W7, F10, W19, F27, F31 or long aliphatic (I14, I24 side chains. Furthermore, some of the N-terminal mutations (e.g. I14A, I24A, F31A affected the N protein functionality both in mammalian two-hybrid and minigenome assays. Conclusions UUKV-N protein has ability to form oligomers in chemical cross-linking and mammalian two-hybrid assays. In mutational analysis, some of the introduced single-point mutations abolished the N protein functionality both in mammalian two-hybrid and minigenome assays, suggesting that especially the N

  17. Revisiting the oligomerization mechanism of Vibrio cholerae cytolysin, a beta-barrel pore-forming toxin.

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    Rai, Anand Kumar; Chattopadhyay, Kausik

    2016-06-03

    Vibrio cholerae cytolysin (VCC) is a membrane-damaging beta-barrel pore-forming toxin (beta-PFT). VCC causes permeabilization of the target membranes by forming transmembrane oligomeric beta-barrel pores. Oligomerization is a key step in the mode of action of any beta-PFT, including that of VCC. Earlier studies have identified some of the key residues in VCC that are directly involved in the generation of the inter-protomer contacts, thus playing critical roles in the oligomerization of the membrane-bound toxin. Analysis of the VCC oligomeric pore structure reveals a potential hydrogen-bond network that appears to connect the sidechain of an asparagine residue (Asn582; located within an inter-domain linker sequence) from one protomer to the backbone CO- and NH-groups of the neighbouring protomer, indirectly through water molecules at most of the inter-protomer interfaces. In the present study, we show that the mutation of Asn582Ala affects the oligomerization and the pore-forming activity of VCC in the membrane lipid bilayer of the synthetic lipid vesicles, while the replacement of Asn582Gln results into the restoration of the oligomeric pore-forming ability of the toxin. Using a number of truncated variants of VCC, having deletion in the C-terminal region of the toxin starting from the Asn582 residue or beyond, we also show that the presence of Asn582 is critically required for the oligomerization of the truncated form of the protein.

  18. Identification of benzimidazole diamides as selective inhibitors of the nucleotide-binding oligomerization domain 2 (NOD2 signaling pathway.

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    David J Rickard

    Full Text Available NOD2 is an intracellular pattern recognition receptor that assembles with receptor-interacting protein (RIP-2 kinase in response to the presence of bacterial muramyl dipeptide (MDP in the host cell cytoplasm, thereby inducing signals leading to the production of pro-inflammatory cytokines. The dysregulation of NOD2 signaling has been associated with various inflammatory disorders suggesting that small-molecule inhibitors of this signaling complex may have therapeutic utility. To identify inhibitors of the NOD2 signaling pathway, we utilized a cell-based screening approach and identified a benzimidazole diamide compound designated GSK669 that selectively inhibited an MDP-stimulated, NOD2-mediated IL-8 response without directly inhibiting RIP2 kinase activity. Moreover, GSK669 failed to inhibit cytokine production in response to the activation of Toll-like receptor (TLR-2, tumor necrosis factor receptor (TNFR-1 and closely related NOD1, all of which share common downstream components with the NOD2 signaling pathway. While the inhibitors blocked MDP-induced NOD2 responses, they failed to block signaling induced by NOD2 over-expression or single stranded RNA, suggesting specificity for the MDP-induced signaling complex and activator-dependent differences in NOD2 signaling. Investigation of structure-activity relationship allowed the identification of more potent analogs that maintained NOD2 selectivity. The largest boost in activity was achieved by N-methylation of the C2-ethyl amide group. These findings demonstrate that the NOD2 signaling pathway is amenable to modulation by small molecules that do not target RIP2 kinase activity. The compounds we identified should prove useful tools to investigate the importance of NOD2 in various inflammatory processes and may have potential clinical utility.

  19. Identification of Benzimidazole Diamides as Selective Inhibitors of the Nucleotide-Binding Oligomerization Domain 2 (NOD2) Signaling Pathway

    Science.gov (United States)

    Rickard, David J.; Sehon, Clark A.; Kasparcova, Viera; Kallal, Lorena A.; Zeng, Xin; Montoute, Monica N.; Chordia, Tushar; Poore, Derek D.; Li, Hu; Wu, Zining; Eidam, Patrick M.; Haile, Pamela A.; Yu, Jong; Emery, John G.; Marquis, Robert W.; Gough, Peter J.; Bertin, John

    2013-01-01

    NOD2 is an intracellular pattern recognition receptor that assembles with receptor-interacting protein (RIP)-2 kinase in response to the presence of bacterial muramyl dipeptide (MDP) in the host cell cytoplasm, thereby inducing signals leading to the production of pro-inflammatory cytokines. The dysregulation of NOD2 signaling has been associated with various inflammatory disorders suggesting that small-molecule inhibitors of this signaling complex may have therapeutic utility. To identify inhibitors of the NOD2 signaling pathway, we utilized a cell-based screening approach and identified a benzimidazole diamide compound designated GSK669 that selectively inhibited an MDP-stimulated, NOD2-mediated IL-8 response without directly inhibiting RIP2 kinase activity. Moreover, GSK669 failed to inhibit cytokine production in response to the activation of Toll-like receptor (TLR)-2, tumor necrosis factor receptor (TNFR)-1 and closely related NOD1, all of which share common downstream components with the NOD2 signaling pathway. While the inhibitors blocked MDP-induced NOD2 responses, they failed to block signaling induced by NOD2 over-expression or single stranded RNA, suggesting specificity for the MDP-induced signaling complex and activator-dependent differences in NOD2 signaling. Investigation of structure-activity relationship allowed the identification of more potent analogs that maintained NOD2 selectivity. The largest boost in activity was achieved by N-methylation of the C2-ethyl amide group. These findings demonstrate that the NOD2 signaling pathway is amenable to modulation by small molecules that do not target RIP2 kinase activity. The compounds we identified should prove useful tools to investigate the importance of NOD2 in various inflammatory processes and may have potential clinical utility. PMID:23936340

  20. Oligomeric proanthocyanidins from mangosteen pericarps.

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    Fu, Caili; Loo, Alvin Eng Kiat; Chia, Fiona Ping Ping; Huang, Dejian

    2007-09-19

    Oligomeric proanthocyanidins were extracted from mangosteen pericarps and fractionated by a Sephadex LH-20 column to give 0.66% yield (dry matter). (13)C and (1)H NMR signals showed the presence of predominantly procyanidins together with a few prodelphinidin units along with small amounts of stereoisomers of afzelechin/epiafzelechin, catechin/epicatechin, and gallocatechin/epigallocatechin. Depolymerization with benzylmercaptan resulted in epicatechin thioether as the major product, and the mean degree of polymerization was determined to be 6.6. The electron spray ionization-mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectra revealed the dominant B type oligomers with mainly epicatechin units and with a small amount of A type oligomers. The isolated proanthocyanidins are potent peroxyl radical scavengers as evidenced by the high oxygen radical scavenging capacity at 1.7 x 10 (4) micromol TE/g, much higher than that of pine bark and grape seed extracts.

  1. Thermodynamic competition between membrane protein oligomeric states

    Science.gov (United States)

    Kahraman, Osman; Haselwandter, Christoph A.

    2016-10-01

    Self-assembly of protein monomers into distinct membrane protein oligomers provides a general mechanism for diversity in the molecular architectures, and resulting biological functions, of membrane proteins. We develop a general physical framework describing the thermodynamic competition between different oligomeric states of membrane proteins. Using the mechanosensitive channel of large conductance as a model system, we show how the dominant oligomeric states of membrane proteins emerge from the interplay of protein concentration in the cell membrane, protein-induced lipid bilayer deformations, and direct monomer-monomer interactions. Our results suggest general physical mechanisms and principles underlying regulation of protein function via control of membrane protein oligomeric state.

  2. Thermodynamic competition between membrane protein oligomeric states

    CERN Document Server

    Kahraman, Osman

    2016-01-01

    Self-assembly of protein monomers into distinct membrane protein oligomers provides a general mechanism for diversity in the molecular architectures, and resulting biological functions, of membrane proteins. We develop a general physical framework describing the thermodynamic competition between different oligomeric states of membrane proteins. Using the mechanosensitive channel of large conductance as a model system, we show how the dominant oligomeric states of membrane proteins emerge from the interplay of protein concentration in the cell membrane, protein-induced lipid bilayer deformations, and direct monomer-monomer interactions. Our results suggest general physical mechanisms and principles underlying regulation of protein function via control of membrane protein oligomeric state.

  3. Reversible peptide oligomerization over nanoscale gold surfaces

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    Kazushige Yokoyama

    2015-11-01

    Full Text Available A selective oligomeric formation of amyloid beta 1-40 (Ab1-40 monomers over a nanogold colloidal surface was investigated. An unfolded Ab1-40 monomer is considered to construct a dimer or trimer based oligomeric form with its hydrophobic segment placing outward under an acidic condition. Under a basic condition, a conformation of Ab is expected to take a folded monomeric form with its hydrophilic segment folded inward, avoiding the networking with residual colloidal particles. The most probable oligomeric form constructed over a 20 nm gold colloidal surface within a 25 ℃ to 65 ℃ temperature range is a dimer based unit and that over 30 or 40 nm gold colloidal surface below 15 ℃ is concluded to be a trimer based unit. However, selective oligomerization was not successfully reproduced under the rest of the conditions. A dipole-induced dipole interaction must cause a flexible structural change between folded and unfolded forms.

  4. Carbon Nanostructures Containing Polyhedral Oligomeric Silsesquioxanes (POSS)

    NARCIS (Netherlands)

    Potsi, Georgia; Rossos, Andreas; Kouloumpis, Antonios; Antoniou, Myrsini K.; Spyrou, Konstantinos; Karakassides, Michael A.; Gournis, Dimitrios; Rudolf, Petra

    2015-01-01

    This mini review describes the synthesis and properties of carbon nanostructures containing organic-inorganic cage-like polyhedral oligomeric silsesquioxane (POSS). The physical and chemical functionalization of carbon nanomaterials such as graphene, graphene oxide, carbon nanotubes, and fullerenes

  5. Carbon Nanostructures Containing Polyhedral Oligomeric Silsesquioxanes (POSS)

    NARCIS (Netherlands)

    Potsi, Georgia; Rossos, Andreas; Kouloumpis, Antonios; Antoniou, Myrsini K.; Spyrou, Konstantinos; Karakassides, Michael A.; Gournis, Dimitrios; Rudolf, Petra

    2015-01-01

    This mini review describes the synthesis and properties of carbon nanostructures containing organic-inorganic cage-like polyhedral oligomeric silsesquioxane (POSS). The physical and chemical functionalization of carbon nanomaterials such as graphene, graphene oxide, carbon nanotubes, and fullerenes

  6. N-(1-Pyrenyl Maleimide Induces Bak Oligomerization and Mitochondrial Dysfunction in Jurkat Cells

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    Pei-Rong Huang

    2015-01-01

    Full Text Available N-(1-pyrenyl maleimide (NPM is a fluorescent reagent that is frequently used as a derivatization agent for the detection of thio-containing compounds. NPM has been shown to display a great differential cytotoxicity against hematopoietic cancer cells. In this study, the molecular mechanism by which NPM induces apoptosis was examined. Here, we show that treatment of Jurkat cells with NPM leads to Bak oligomerization, loss of mitochondrial membrane potential (Δψm, and release of cytochrome C from mitochondria to cytosol. Induction of Bak oligomerization appears to play a critical role in NPM-induced apoptosis, as downregulation of Bak by shRNA significantly prevented NPM-induced apoptosis. Inhibition of caspase 8 by Z-IETD-FMK and/or depletion of Bid did not affect NPM-induced oligomerization of Bak. Taken together, these results suggest that NPM-induced apoptosis is mediated through a pathway that is independent of caspase-8 activation.

  7. Dimerization and oligomerization of the chaperone calreticulin

    DEFF Research Database (Denmark)

    Jørgensen, Charlotte S; Ryder, L Rebekka; Steinø, Anne;

    2003-01-01

    protein. Using PAGE, urea gradient gel electrophoresis, capillary electrophoresis and MS, we show that dimerization through the SH group can be induced by lowering the pH to 5-6, heating, or under conditions that favour partial unfolding such as urea concentrations above 2.6 m or SDS concentrations above...... 0.025%. Moreover, we show that calreticulin also has the ability to self-oligomerize through noncovalent interactions at urea concentrations above 2.6 m at pH below 4.6 or above pH 10, at temperatures above 40 degrees C, or in the presence of high concentrations of organic solvents (25%), conditions...... urea or 1% SDS, and heat-induced oligomerization could be inhibited by 8 m urea or 1% SDS when present during heating. Comparison of the binding properties of monomeric and oligomeric calreticulin in solid-phase assays showed increased binding to peptides and denatured proteins when calreticulin...

  8. Oligomeric secoiridoid glucosides from Jasminum abyssinicum.

    Science.gov (United States)

    Gallo, Francesca Romana; Palazzino, Giovanna; Federici, Elena; Iurilli, Raffaella; Monache, Franco Delle; Chifundera, Kusamba; Galeffi, Corrado

    2006-03-01

    From the root bark of Jasminum abyssinicum (Oleaceae) collected in Congo was isolated tree oligomeric secoiridoid glucosides named craigosides A-C. The three compounds are esters of a cyclopentanoid monoterpene with an iridane skeleton, esterified with three, two and two, respectively, units of oleoside 11-methyl ester. The structures were elucidated by spectroscopic methods and chemical correlations.

  9. Simulations of Oligomeric Intermediates in Prion Diseases

    CERN Document Server

    Mobley, D L; Singh, R R P; Kulkarni, R V; Slepoy, A; Mobley, David L.; Cox, Daniel L.; Singh, Rajiv R. P.; Kulkarni, Rahul V.; Slepoy, Alexander

    2003-01-01

    We extend our previous stochastic cellular automata based model for areal aggregation of prion proteins on neuronal surfaces. The new anisotropic model allow us to simulate both strong beta-sheet and weaker attachment bonds between proteins. Constraining binding directions allows us to generate aggregate structures with the hexagonal lattice symmetry found in recently observed in vitro experiments. We argue that these constraints on rules may correspond to underlying steric constraints on the aggregation process. We find that monomer dominated growth of the areal aggregate is too slow to account for some observed doubling time-to-incubation time ratios inferred from data, and so consider aggregation dominated by relatively stable but non-infectious oligomeric intermediates. We compare a kinetic theory analysis of oligomeric aggregation to spatially explicit simulations of the process. We find that with suitable rules for misfolding of oligomers, possibly due to water exclusion by the surrounding aggregate, th...

  10. Metal Catalyzed Oligomerization Reactions of Organosiloxanes.

    Science.gov (United States)

    1982-10-28

    Table I. Some monosilanes , e.g. Me3SiH and PhMe2SiH, are found, but none of the expected PhMeSiH 2 is present. However, some of the expected oligomeric...of the monosilanes as indicated in Table I suggested that reaction 17 does occur, but the initially produced PhMeSiH 2 undergoes secondary

  11. Systematic comparison of the effects of alpha-synuclein mutations on its oligomerization and aggregation.

    Directory of Open Access Journals (Sweden)

    Diana F Lázaro

    2014-11-01

    Full Text Available Aggregation of alpha-synuclein (ASYN in Lewy bodies and Lewy neurites is the typical pathological hallmark of Parkinson's disease (PD and other synucleinopathies. Furthermore, mutations in the gene encoding for ASYN are associated with familial and sporadic forms of PD, suggesting this protein plays a central role in the disease. However, the precise contribution of ASYN to neuronal dysfunction and death is unclear. There is intense debate about the nature of the toxic species of ASYN and little is known about the molecular determinants of oligomerization and aggregation of ASYN in the cell. In order to clarify the effects of different mutations on the propensity of ASYN to oligomerize and aggregate, we assembled a panel of 19 ASYN variants and compared their behaviour. We found that familial mutants linked to PD (A30P, E46K, H50Q, G51D and A53T exhibited identical propensities to oligomerize in living cells, but had distinct abilities to form inclusions. While the A30P mutant reduced the percentage of cells with inclusions, the E46K mutant had the opposite effect. Interestingly, artificial proline mutants designed to interfere with the helical structure of the N-terminal domain, showed increased propensity to form oligomeric species rather than inclusions. Moreover, lysine substitution mutants increased oligomerization and altered the pattern of aggregation. Altogether, our data shed light into the molecular effects of ASYN mutations in a cellular context, and established a common ground for the study of genetic and pharmacological modulators of the aggregation process, opening new perspectives for therapeutic intervention in PD and other synucleinopathies.

  12. Polybenzoxazine/Polyhedral Oligomeric Silsesquioxane (POSS Nanocomposites

    Directory of Open Access Journals (Sweden)

    Mohamed Gamal Mohamed

    2016-06-01

    Full Text Available The organic/inorganic hybrid materials from polyhedral oligomeric silsesquioxane (POSS, inorganic nanoparticles and polybenzoxazine (PBZ have received much interesting recently due to their excellent thermal and mechanical properties, flame retardance, low dielectric constant, well-defined inorganic framework at nanosized scale level, and higher performance relative to those of non-hybrid PBZs. This review describes the synthesis, dielectric constants, and thermal, rheological, and mechanical properties of covalently bonded mono- and multifunctionalized benzoxazine POSS hybrids, other functionalized benzoxazine POSS derivatives, and non-covalently (hydrogen bonded benzoxazine POSS composites.

  13. Play Matters

    DEFF Research Database (Denmark)

    Sicart (Vila), Miguel Angel

    , but not necessarily fun. Play can be dangerous, addictive, and destructive. Along the way, Sicart considers playfulness, the capacity to use play outside the context of play; toys, the materialization of play--instruments but also play pals; playgrounds, play spaces that enable all kinds of play; beauty......, the aesthetics of play through action; political play -- from Maradona's goal against England in the 1986 World Cup to the hactivist activities of Anonymous; the political, aesthetic, and moral activity of game design; and why play and computers get along so well....

  14. Endocytic pathways mediating oligomeric Aβ42 neurotoxicity

    Directory of Open Access Journals (Sweden)

    Laxton Kevin

    2010-05-01

    Full Text Available Abstract Background One pathological hallmark of Alzheimer's disease (AD is amyloid plaques, composed primarily of amyloid-β peptide (Aβ. Over-production or diminished clearance of the 42 amino acid form of Aβ (Aβ42 in the brain leads to accumulation of soluble Aβ and plaque formation. Soluble oligomeric Aβ (oAβ has recently emerged to be as a likely proximal cause of AD. Results Here we demonstrate that endocytosis is critical in mediating oAβ42-induced neurotoxicity and intraneuronal accumulation of Aβ. Inhibition of clathrin function either with a pharmacological inhibitor, knock-down of clathrin heavy chain expression, or expression of the dominant-negative mutant of clathrin-assembly protein AP180 did not block oAβ42-induced neurotoxicity or intraneuronal accumulation of Aβ. However, inhibition of dynamin and RhoA by expression of dominant negative mutants reduced neurotoxicity and intraneuronal Aβ accumulation. Pharmacologic inhibition of the dynamin-mediated endocytic pathway by genistein also reduced neurotoxicity. Conclusions These data suggest that dynamin-mediated and RhoA-regulated endocytosis are integral steps for oligomeric Aβ42-induced neurotoxicity and intraneuronal Aβ accumulation.

  15. Domain architecture and oligomerization properties of the paramyxovirus PIV 5 hemagglutinin-neuraminidase (HN) protein.

    Science.gov (United States)

    Yuan, Ping; Leser, George P; Demeler, Borries; Lamb, Robert A; Jardetzky, Theodore S

    2008-09-01

    The mechanism by which the paramyxovirus hemagglutinin-neuraminidase (HN) protein couples receptor binding to activation of virus entry remains to be fully understood, but the HN stalk is thought to play an important role in the process. We have characterized ectodomain constructs of the parainfluenza virus 5 HN to understand better the underlying architecture and oligomerization properties that may influence HN functions. The PIV 5 neuraminidase (NA) domain is monomeric whereas the ectodomain forms a well-defined tetramer. The HN stalk also forms tetramers and higher order oligomers with high alpha-helical content. Together, the data indicate that the globular NA domains form weak intersubunit interactions at the end of the HN stalk tetramer, while stabilizing the stalk and overall oligomeric state of the ectodomain. Electron microscopy of the HN ectodomain reveals flexible arrangements of the NA and stalk domains, which may be important for understanding how these two HN domains impact virus entry.

  16. Playful Gaming.

    Science.gov (United States)

    Makedon, Alexander

    A philosophical analysis of play and games is undertaken in this paper. Playful gaming, which is shown to be a synthesis of play and games, is utilized as a category for undertaking the examination of play and games. The significance of playful gaming to education is demonstrated through analyses of Plato's, Dewey's, Sartre's, and Marcuse's…

  17. Antioxidant oligomeric proanthocyanidins from Cistus salvifolius.

    Science.gov (United States)

    Qa'Dan, Fadi; Petereit, Frank; Mansoor, Kenza; Nahrstedt, Adolf

    2006-11-01

    The purified proanthocyanidin oligomers of Cistus salvifolius herb extract accounted for 78% of the total proanthocyanidins and 73% of the total antioxidant activity of this extract. To elucidate the structure of the oligomer, it was depolymerized by acid catalysis in the presence of phloroglucinol. The structures of the resulting flavan-3-ols and phloroglucinol adducts were determined on the basis of 1D- and reverse 2D-NMR (HSQC, HMBC) experiments of their peracetylated derivatives, MALDI-TOF-MS and CD spectroscopy. These observations resulting from the degradation with phloroglucinol were confirmed by 13C NMR spectroscopy of the oligomer. The mean molecular weight of the higher oligomeric fraction was estimated to be 5-6 flavan-3-ol-units.

  18. Genetic noise control via protein oligomerization

    Energy Technology Data Exchange (ETDEWEB)

    Ghim, C; Almaas, E

    2008-06-12

    Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamical role of protein-protein associations. We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch), integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast protein binding-unbinding kinetics, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its intrinsic switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced) state from randomly being induced (uninduced). The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of phenotypically important toggle switches, and nested positive feedback loops in

  19. Aesthetic Play

    DEFF Research Database (Denmark)

    Bang, Jytte Susanne

    2012-01-01

    to the children’s complex life-worlds. Further, this leads to an analysis of music-play activities as play with an art-form (music), which includes aesthetic dimensions and gives the music-play activities its character of being aesthetic play. Following Lev Vygotsky’s insight that art is a way of building life...

  20. Differential structural remodelling of heparan sulfate by chemokines: the role of chemokine oligomerization

    Science.gov (United States)

    Migliorini, Elisa; Salanga, Catherina L.; Thakar, Dhruv

    2017-01-01

    Chemokines control the migration of cells in normal physiological processes and in the context of disease such as inflammation, autoimmunity and cancer. Two major interactions are involved: (i) binding of chemokines to chemokine receptors, which activates the cellular machinery required for movement; and (ii) binding of chemokines to glycosaminoglycans (GAGs), which facilitates the organization of chemokines into haptotactic gradients that direct cell movement. Chemokines can bind and activate their receptors as monomers; however, the ability to oligomerize is critical for the function of many chemokines in vivo. Chemokine oligomerization is thought to enhance their affinity for GAGs, and here we show that it significantly affects the ability of chemokines to accumulate on and be retained by heparan sulfate (HS). We also demonstrate that several chemokines differentially rigidify and cross-link HS, thereby affecting HS rigidity and mobility, and that HS cross-linking is significantly enhanced by chemokine oligomerization. These findings suggest that chemokine–GAG interactions may play more diverse biological roles than the traditional paradigms of physical immobilization and establishment of chemokine gradients; we hypothesize that they may promote receptor-independent events such as physical re-organization of the endothelial glycocalyx and extracellular matrix, as well as signalling through proteoglycans to facilitate leukocyte adhesion and transmigration. PMID:28123055

  1. Toll-like receptor-induced granulocyte-macrophage colony-stimulating factor secretion is impaired in Crohn's disease by nucleotide oligomerization domain 2-dependent and -independent pathways

    DEFF Research Database (Denmark)

    Brosbøl-Ravnborg, A; Hvas, C L; Agnholt, J

    2008-01-01

    factor (TNF)-alpha. In CD patients, TLR-induced GM-CSF secretion was impaired by both NOD2-dependent and -independent mechanisms. Moreover, TNF-alpha production was induced by a TLR-2 ligand, but a down-regulatory function by the NOD2 ligand, muramyl dipeptide, was impaired significantly in CD patients....... Intracellular TLR ligands had minimal effect on GM-CSF, TNF-alpha and IL-1beta secretion. CD patients with NOD2 mutations were able to secrete TNF-alpha, but not GM-CSF, upon stimulation with NOD2 and TLR-7 ligands. CD patients have impaired GM-CSF secretion via NOD2-dependent and -independent pathways...... and display an impaired NOD2-dependent down-regulation of TNF-alpha secretion. The defect in GM-CSF secretion suggests a hitherto unknown role of NOD2 in the pathogenesis of CD and is consistent with the hypothesis that impaired GM-CSF secretion in part constitutes a NOD2-dependent disease risk factor....

  2. Toll-like receptor-induced granulocyte-macrophage colony-stimulating factor secretion is impaired in Crohn's disease by nucleotide oligomerization domain 2-dependent and -independent pathways

    DEFF Research Database (Denmark)

    Ravnborg, Anne Brosbøl-; Hvas, Christian Lodberg; Agnholt, Jørgen

    2009-01-01

    factor (TNF)-alpha. In CD patients, TLR-induced GM-CSF secretion was impaired by both NOD2-dependent and -independent mechanisms. Moreover, TNF-alpha production was induced by a TLR-2 ligand, but a down-regulatory function by the NOD2 ligand, muramyl dipeptide, was impaired significantly in CD patients....... Intracellular TLR ligands had minimal effect on GM-CSF, TNF-alpha and IL-1beta secretion. CD patients with NOD2 mutations were able to secrete TNF-alpha, but not GM-CSF, upon stimulation with NOD2 and TLR-7 ligands. CD patients have impaired GM-CSF secretion via NOD2-dependent and -independent pathways...... and display an impaired NOD2-dependent down-regulation of TNF-alpha secretion. The defect in GM-CSF secretion suggests a hitherto unknown role of NOD2 in the pathogenesis of CD and is consistent with the hypothesis that impaired GM-CSF secretion in part constitutes a NOD2-dependent disease risk factor....

  3. Ordering properties of oligomeric columnar discotic liquid crystals

    NARCIS (Netherlands)

    Umesh, C.P.

    2015-01-01

    The synthesis and liquid crystalline ordering properties of oligomeric discotic liquid crystals were investigated. The phase behaviour and surface ordering properties are dependent on among others core type, spacer length and fluorination.    

  4. Cartilage oligomeric matrix protein in patients with juvenile idiopathic arthritis

    DEFF Research Database (Denmark)

    Bjørnhart, Birgitte; Juul, Anders; Nielsen, Susan

    2009-01-01

    Cartilage oligomeric matrix protein (COMP) has been identified as a prognostic marker of progressive joint destruction in rheumatoid arthritis. In this population based study we evaluated associations between plasma concentrations of COMP, disease activity, and growth velocity in patients...

  5. Aesthetic Play

    DEFF Research Database (Denmark)

    Bang, Jytte Susanne

    2012-01-01

    The present article explores the role of music-related artefacts and technologies in children’s lives. More specifically, it analyzes how four 10- to 11-year old girls use CDs and DVD games in their music-play activities and which developmental themes and potentials may accrue from such activities...... to the children’s complex life-worlds. Further, this leads to an analysis of music-play activities as play with an art-form (music), which includes aesthetic dimensions and gives the music-play activities its character of being aesthetic play. Following Lev Vygotsky’s insight that art is a way of building life...

  6. Hydrodynamic and functional analysis of HIV-1 Vif oligomerization.

    Science.gov (United States)

    Techtmann, Stephen M; Ghirlando, Rodolfo; Kao, Sandra; Strebel, Klaus; Maynard, Ernest L

    2012-03-13

    HIV-1 Vif is an accessory protein that induces the proteasomal degradation of the host restriction factor, apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G (APOBEC3G). The N-terminal half of Vif binds to APOBEC3G, and the C-terminal half binds to subunits of a cullin 5-based ubiquitin ligase. This Vif-directed ubiquitin ligase induces the degradation of APOBEC3G (a cytidine deaminase) and thereby protects the viral genome from mutation. A conserved PPLP motif near the C-terminus of Vif is essential for Vif function and is also involved in Vif oligomerization. However, the mechanism and functional significance of Vif oligomerization is unclear. We employed analytical ultracentrifugation to examine the oligomeric properties of Vif in solution. Contrary to previous reports, we find that Vif oligomerization does not require the conserved PPLP motif. Instead, our data suggest a more complex mechanism involving interactions among the HCCH motif, the BC box, and downstream residues in Vif. Mutation of residues near the PPLP motif (S165 and V166) affected the oligomeric properties of Vif and weakened the ability of Vif to bind and induce the degradation of APOBEC3G. We propose that Vif oligomerization may represent a mechanism for regulating interactions with APOBEC3G.

  7. Oligomerization paths of the nucleoprotein of influenza A virus.

    Science.gov (United States)

    Tarus, B; Bakowiez, O; Chenavas, S; Duchemin, L; Estrozi, L F; Bourdieu, C; Lejal, N; Bernard, J; Moudjou, M; Chevalier, C; Delmas, B; Ruigrok, R W H; Di Primo, C; Slama-Schwok, A

    2012-03-01

    The influenza viruses contain a segmented, negative strand RNA genome. Each RNA segment is covered by multiple copies of the nucleoprotein (NP) and is associated with the polymerase complex into ribonucleoprotein (RNP) particles. Despite its importance in the virus life cycle, the interactions between the NP and the genome are not well understood. Here, we studied the assembly process of NP-RNA oligomers and analyzed how the oligomeric/monomeric status of RNA-free NP affects RNA binding and oligomerization. Recombinant wild-type NP purified in low salt concentrations and a derived mutant engineered for oligomerization deficiency (R416A) were mainly monomeric in RNA-free solutions as shown by biochemical and electron microscopy techniques. NP monomer formed with RNA a fast 1/1 complex characterized by surface plasmon resonance. In a subsequent and slow process that depended on the RNA length, oligomerization of NP was mediated by RNA binding. In contrast, preparations of wild-type NP purified in high salt concentrations as well as mutant Y148A engineered for deficiency in nucleic acid binding were partly or totally oligomeric in RNA-free solutions. These trimer/tetramer NP oligomers bind directly as oligomers to RNA with a higher affinity than that of the monomers. Both oligomerization routes we characterized could be exploited by cellular or viral factors to modulate or control viral RNA encapsidation by NP. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  8. Playful Membership

    DEFF Research Database (Denmark)

    Åkerstrøm Andersen, Niels; Pors, Justine Grønbæk

    2014-01-01

    This article studies the implications of current attempts by organizations to adapt to a world of constant change by introducing the notion of playful organizational membership. To this end we conduct a brief semantic history of organizational play and argue that when organizations play, employees...... are expected to engage in playful exploration of alternative selves. Drawing on Niklas Luhmann's theory of time and decision-making and Gregory Bateson's theory of play, the article analyses three empirical examples of how games play with conceptions of time. We explore how games represent an organizational...... desire to reach out - not just to the future - but to futures beyond the future presently imaginable. The article concludes that playful membership is membership through which employees are expected to develop a surplus of potential identities and continuously cross boundaries between real and virtual...

  9. Lanthanide Complexes for Oligomerization of Phenyl Isocyanate

    Institute of Scientific and Technical Information of China (English)

    DENG,Ming-Yu; YAO,Ying-Ming; ZHOU,Yu-Fang; ZHANG,Li-Fen; SHEN,Qi

    2003-01-01

    A series of lanthanide complexes including (Ind)3Sm(THF)(1),[(MeCp)2Sm(μ-SPh)(THF)]2(2),[(MeCp)2Y(μ-O-i-Pr)]2(3),(MeCp)3Sm·THF(4),Sm(SPh)3(hmpa)3(5),[(MeCp)2Y-(μ-OCH2CF3)2(6)and (CF3CH2O)3Y(THF)3(7) were synthesized and they have good activity for the oligomerization of phenylisocyanate.Among them 5 shows the highest activity.The conversion is as high as 96.2%,with 1/2500 of the molar ratio of cat./PhNCO.The main components in oligomer were characterized to be a cycdlodimer and a cyclotrimer.The ratio of cyclodimer to cyclotrimer depends on the lanthanide complexes used.7 gave 85.2%cyclotrimer with 1/300 of the molar ratio of cat./PhNCO at 40℃ for 0.5h,while 5 gave 77.6% cyclodimer with 1/300 of the molar ratio of cat./PhNCO at 40℃ for 4h.

  10. Orally administrated cinnamon extract reduces β-amyloid oligomerization and corrects cognitive impairment in Alzheimer's disease animal models.

    Directory of Open Access Journals (Sweden)

    Anat Frydman-Marom

    Full Text Available An increasing body of evidence indicates that accumulation of soluble oligomeric assemblies of β-amyloid polypeptide (Aβ play a key role in Alzheimer's disease (AD pathology. Specifically, 56 kDa oligomeric species were shown to be correlated with impaired cognitive function in AD model mice. Several reports have documented the inhibition of Aβ plaque formation by compounds from natural sources. Yet, evidence for the ability of common edible elements to modulate Aβ oligomerization remains an unmet challenge. Here we identify a natural substance, based on cinnamon extract (CEppt, which markedly inhibits the formation of toxic Aβ oligomers and prevents the toxicity of Aβ on neuronal PC12 cells. When administered to an AD fly model, CEppt rectified their reduced longevity, fully recovered their locomotion defects and totally abolished tetrameric species of Aβ in their brain. Furthermore, oral administration of CEppt to an aggressive AD transgenic mice model led to marked decrease in 56 kDa Aβ oligomers, reduction of plaques and improvement in cognitive behavior. Our results present a novel prophylactic approach for inhibition of toxic oligomeric Aβ species formation in AD through the utilization of a compound that is currently in use in human diet.

  11. Playful Literacy

    DEFF Research Database (Denmark)

    Froes, Isabel

    2017-01-01

    these practices, which compose the taxonomy of tablet play. My contribution lies in identifying and proposing a series of theoretical concepts that complement recent theories related to play and digital literacy studies. The data collected through observations informed some noteworthy aspects, including how...... with tablets’ physical and digital affordances shape children’s digital play. This thesis presents how young children’s current practices when playing with tablets inform digital experiences in Denmark and Japan. Through an interdisciplinary lens and a grounded theory approach, I have identified and mapped...... vocabulary in children’s digital play experiences. These early digital experiences set the rules for the playgrounds and assert digital tablets as twenty-first-century toys, shaping young children’s playful literacy....

  12. Pretend play.

    Science.gov (United States)

    Weisberg, Deena Skolnick

    2015-01-01

    Pretend play is a form of playful behavior that involves nonliteral action. Although on the surface this activity appears to be merely for fun, recent research has discovered that children's pretend play has connections to important cognitive and social skills, such as symbolic thinking, theory of mind, and counterfactual reasoning. The current article first defines pretend play and then reviews the arguments and evidence for these three connections. Pretend play has a nonliteral correspondence to reality, hence pretending may provide children with practice with navigating symbolic relationships, which may strengthen their language skills. Pretend play and theory of mind reasoning share a focus on others' mental states in order to correctly interpret their behavior, hence pretending and theory of mind may be mutually supportive in development. Pretend play and counterfactual reasoning both involve representing nonreal states of affairs, hence pretending may facilitate children's counterfactual abilities. These connections make pretend play an important phenomenon in cognitive science: Studying children's pretend play can provide insight into these other abilities and their developmental trajectories, and thereby into human cognitive architecture and its development.

  13. Playful Interaction

    DEFF Research Database (Denmark)

    2003-01-01

    The video Playful Interaction describes a future architectural office, and envisions ideas and concepts for playful interactions between people, materials and appliances in a pervasive and augmented working environment. The video both describes existing developments, technologies and designs...... as well as ideas not yet implemented such as playful modes of interaction with an augmented ball. Playful Interaction has been used as a hybrid of a vision video and a video prototype (1). Externally the video has been used to visualising our new ideas, and internally the video has also worked to inspire...

  14. Mediatized play

    DEFF Research Database (Denmark)

    Johansen, Stine Liv

    Children’s play must nowadays be understood as a mediatized field in society and culture. Media – understood in a very broad sense - holds severe explanatory power in describing and understanding the practice of play, since play happens both with, through and inspired by media of different sorts....... In this presentation the case of ‘playing soccer’ will be outlined through its different mediated manifestations, including soccer games and programs on TV, computer games, magazines, books, YouTube videos and soccer trading cards....

  15. Play practices and play moods

    DEFF Research Database (Denmark)

    Karoff, Helle Skovbjerg

    2013-01-01

    The aim of this article is to develop a view of play as a relation between play practices and play moods based on an empirical study of children's everyday life and by using Bateson's term of ‘framing’ [(1955/2001). In Steps to an ecology of mind (pp. 75–80). Chicago: University of Chicago Press......], Schmidt's notion of ‘commonness’ [(2005). Om respekten. København: Danmarks Pædagogiske Universitets Forlag; (2011). On respect. Copenhagen: Danish School of Education University Press] and Heidegger's term ‘mood’ [(1938/1996). Time and being. Cornwall: Wiley-Blackwell.]. Play mood is a state of being...... in which we are open and ready, both to others and their production of meaning and to new opportunities for producing meaning. This play mood is created when we engage with the world during play practices. The article points out four types of play moods – devotion, intensity, tension and euphorica – which...

  16. Characterization and preparation of oligomeric procyanidins from Litchi chinensis pericarp.

    Science.gov (United States)

    Sui, Yong; Zheng, Yan; Li, Xiaopeng; Li, Shuyi; Xie, Bijun; Sun, Zhida

    2016-07-01

    The main purpose of this study is to characterize and prepare A-type oligomeric procyanidins from litchi pericarp (Litchi chinensis Baila). The variety of oligomeric procyanidins was characterized by LC-ESI-MS analysis. There were (+)-catechin, (-)-epicatechin, twelve dimers and six trimers of procyanidins were found in litchi pericarp extracts, and A-type procyanidins were much more abundant than B-type procyanidins. The main flavan-3-ol monomer and oligomeric procyanidins in litchi pericarp were (-)-epicatechin, A-type dimers (A1 and A2) and trimer (epicatechin-(4β-8, 2β-O-7)-epicatechin- (4β-8)-epicatechin). Procyanidin A1 (epicatechin-(4β-8, 2β-O-7)-catechin) was identified by NMR in litchi pericarp for the first time. (-)-Epicatechin and oligomeric procyanidins were prepared by the combination of AB-8 column chromatography and Toyopearl HW-40S column chromatography. The results showed that each fraction predominantly owned a single compound and gave a high yield with (-)-epicatechin, A-type dimers (A1 and A2) and trimer, suggesting a useful method to obtain pure (-)-epicatechin and A-type oligomeric procyanidins.

  17. Playful Organizations

    DEFF Research Database (Denmark)

    Pors, Justine Grønbæk; Åkerstrøm Andersen, Niels

    2015-01-01

    and undecidability. With an empirical point of departure in Danish public school policy and two concrete examples of games utilised in school development, the article analyses how play is a way for organisations to simultaneously decide and also avoid making a decision, thus keeping flexibility and possibilities...... intact. In its final sections, the article discusses what happens to conditions of decision-making when organisations do not just see undecidability as a given condition, but as a limited resource indispensable for change and renewal. The article advances discussions of organisational play by exploring......This article explores how organisational play becomes a managerial tool to increase and benefit from undecidability. The article draws on Niklas Luhmann's concept of decision and on Gregory Bateson's theory of play to create a conceptual framework for analysing the relation between decision...

  18. Genetic noise control via protein oligomerization

    Directory of Open Access Journals (Sweden)

    Almaas Eivind

    2008-11-01

    Full Text Available Abstract Background Gene expression in a cell entails random reaction events occurring over disparate time scales. Thus, molecular noise that often results in phenotypic and population-dynamic consequences sets a fundamental limit to biochemical signaling. While there have been numerous studies correlating the architecture of cellular reaction networks with noise tolerance, only a limited effort has been made to understand the dynamic role of protein-protein interactions. Results We have developed a fully stochastic model for the positive feedback control of a single gene, as well as a pair of genes (toggle switch, integrating quantitative results from previous in vivo and in vitro studies. In particular, we explicitly account for the fast binding-unbinding kinetics among proteins, RNA polymerases, and the promoter/operator sequences of DNA. We find that the overall noise-level is reduced and the frequency content of the noise is dramatically shifted to the physiologically irrelevant high-frequency regime in the presence of protein dimerization. This is independent of the choice of monomer or dimer as transcription factor and persists throughout the multiple model topologies considered. For the toggle switch, we additionally find that the presence of a protein dimer, either homodimer or heterodimer, may significantly reduce its random switching rate. Hence, the dimer promotes the robust function of bistable switches by preventing the uninduced (induced state from randomly being induced (uninduced. Conclusion The specific binding between regulatory proteins provides a buffer that may prevent the propagation of fluctuations in genetic activity. The capacity of the buffer is a non-monotonic function of association-dissociation rates. Since the protein oligomerization per se does not require extra protein components to be expressed, it provides a basis for the rapid control of intrinsic or extrinsic noise. The stabilization of regulatory circuits

  19. Oligomeric viral proteins: small in size, large in presence

    Science.gov (United States)

    Jayaraman, Bhargavi; Smith, Amber M.; Fernandes, Jason D.; Frankel, Alan D.

    2016-01-01

    Viruses are obligate parasites that rely heavily on host cellular processes for replication. The small number of proteins typically encoded by a virus is faced with selection pressures that lead to the evolution of distinctive structural properties, allowing each protein to maintain its function under constraints such as small genome size, high mutation rate, and rapidly changing fitness conditions. One common strategy for this evolution is to utilize small building blocks to generate protein oligomers that assemble in multiple ways, thereby diversifying protein function and regulation. In this review, we discuss specific cases that illustrate how oligomerization is used to generate a single defined functional state, to modulate activity via different oligomeric states, or to generate multiple functional forms via different oligomeric states. PMID:27685368

  20. Cartilage oligomeric matrix protein enhances the vascularization of acellular nerves

    Directory of Open Access Journals (Sweden)

    Wei-ling Cui

    2016-01-01

    Full Text Available Vascularization of acellular nerves has been shown to contribute to nerve bridging. In this study, we used a 10-mm sciatic nerve defect model in rats to determine whether cartilage oligomeric matrix protein enhances the vascularization of injured acellular nerves. The rat nerve defects were treated with acellular nerve grafting (control group alone or acellular nerve grafting combined with intraperitoneal injection of cartilage oligomeric matrix protein (experimental group. As shown through two-dimensional imaging, the vessels began to invade into the acellular nerve graft from both anastomotic ends at day 7 post-operation, and gradually covered the entire graft at day 21. The vascular density, vascular area, and the velocity of revascularization in the experimental group were all higher than those in the control group. These results indicate that cartilage oligomeric matrix protein enhances the vascularization of acellular nerves.

  1. Cartilage oligomeric matrix protein enhances the vascularization of acellular nerves

    Institute of Scientific and Technical Information of China (English)

    Wei-ling Cui; Long-hai Qiu; Jia-yan Lian; Jia-chun Li; Jun Hu; Xiao-lin Liu

    2016-01-01

    Vascularization of acellular nerves has been shown to contribute to nerve bridging. In this study, we used a 10-mm sciatic nerve defect model in rats to determine whether cartilage oligomeric matrix protein enhances the vascularization of injured acellular nerves. The rat nerve defects were treated with acellular nerve grafting (control group) alone or acellular nerve grafting combined with intraperitoneal injection of cartilage oligomeric matrix protein (experimental group). As shown through two-dimensional imaging, the vessels began to invade into the acellular nerve graft from both anastomotic ends at day 7 post-operation, and gradually covered the entire graft at day 21. The vascular density, vascular area, and the velocity of revascularization in the experimental group were all higher than those in the control group. These results indicate that cartilage oligomeric matrix protein enhances the vascularization of acellular nerves.

  2. Crystal Structure of the Marburg Virus VP35 Oligomerization Domain.

    Science.gov (United States)

    Bruhn, Jessica F; Kirchdoerfer, Robert N; Urata, Sarah M; Li, Sheng; Tickle, Ian J; Bricogne, Gérard; Saphire, Erica Ollmann

    2017-01-15

    Marburg virus (MARV) is a highly pathogenic filovirus that is classified in a genus distinct from that of Ebola virus (EBOV) (genera Marburgvirus and Ebolavirus, respectively). Both viruses produce a multifunctional protein termed VP35, which acts as a polymerase cofactor, a viral protein chaperone, and an antagonist of the innate immune response. VP35 contains a central oligomerization domain with a predicted coiled-coil motif. This domain has been shown to be essential for RNA polymerase function. Here we present crystal structures of the MARV VP35 oligomerization domain. These structures and accompanying biophysical characterization suggest that MARV VP35 is a trimer. In contrast, EBOV VP35 is likely a tetramer in solution. Differences in the oligomeric state of this protein may explain mechanistic differences in replication and immune evasion observed for MARV and EBOV.

  3. Group play

    DEFF Research Database (Denmark)

    Tychsen, Anders; Hitchens, Michael; Brolund, Thea

    2008-01-01

    of group dynamics, the influence of the fictional game characters and the comparative play experience between the two formats. The results indicate that group dynamics and the relationship between the players and their digital characters, are integral to the quality of the gaming experience in multiplayer......Role-playing games (RPGs) are a well-known game form, existing in a number of formats, including tabletop, live action, and various digital forms. Despite their popularity, empirical studies of these games are relatively rare. In particular there have been few examinations of the effects...... of the various formats used by RPGs on the gaming experience. This article presents the results of an empirical study, examining how multi-player tabletop RPGs are affected as they are ported to the digital medium. Issues examined include the use of disposition assessments to predict play experience, the effect...

  4. Postphenomenological Play

    DEFF Research Database (Denmark)

    Hammar, Emil

    This paper aims to identify an understanding of digital games in virtual environments by using Don Ihde’s (1990) postphenomenological approach to how technology mediates the world to human beings in conjunction with Hans-Georg Gadamer’s (1993) notion of play . Through this tentatively proposed...... amalgamation of theories I point towards an alternative understanding of the relationship between play and game as not only dialectic, but also as socially and ethically relevant qua the design and implementation of the game as technology....

  5. Clay Play

    Science.gov (United States)

    Rogers, Liz; Steffan, Dana

    2009-01-01

    This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

  6. Group play

    DEFF Research Database (Denmark)

    Tychsen, Anders; Hitchens, Michael; Brolund, Thea

    2008-01-01

    Role-playing games (RPGs) are a well-known game form, existing in a number of formats, including tabletop, live action, and various digital forms. Despite their popularity, empirical studies of these games are relatively rare. In particular there have been few examinations of the effects of the v......Role-playing games (RPGs) are a well-known game form, existing in a number of formats, including tabletop, live action, and various digital forms. Despite their popularity, empirical studies of these games are relatively rare. In particular there have been few examinations of the effects...... of the various formats used by RPGs on the gaming experience. This article presents the results of an empirical study, examining how multi-player tabletop RPGs are affected as they are ported to the digital medium. Issues examined include the use of disposition assessments to predict play experience, the effect...... RPGs, with the first being of greater importance to digital games and the latter to the tabletop version....

  7. High Content Analysis of Compositional Heterogeneities to Study GPCR Oligomerization

    DEFF Research Database (Denmark)

    Walsh, Samuel McEwen

    In this thesis I demonstrate how the natural compositional heterogeneities of synthetic and living cell model systems can be used to quantitate the mechanics of G-protein coupled receptor (GPCR) oligomerization with Förster resonance energy transfer (FRET). The thesis is structured around three a...

  8. Cartilage oligomeric matrix protein specific antibodies are pathogenic

    DEFF Research Database (Denmark)

    Geng, Hui; Nandakumar, Kutty Selva; Pramhed, Anna

    2012-01-01

    ABSTRACT: INTRODUCTION: Cartilage oligomeric matrix protein (COMP) is a major non-collagenous component of cartilage. Earlier, we developed a new mouse model for rheumatoid arthritis using COMP. This study was undertaken to investigate the epitope specificity and immunopathogenicity of COMP...

  9. Protic Cationic Oligomeric Ionic Liquids of the Urethane Type

    DEFF Research Database (Denmark)

    Shevchenko, V. V.; Stryutsky, A. V.; Klymenko, N. S.

    2014-01-01

    Protic oligomeric cationic ionic liquids of the oligo(ether urethane) type are synthesized via the reaction of an isocyanate prepolymer based on oligo(oxy ethylene)glycol with M = 1000 with hexamethylene-diisocyanate followed by blocking of the terminal isocyanate groups with the use of amine...

  10. Polyhedral oligomeric silsesquioxane grafted polymer in polymeric foam

    Energy Technology Data Exchange (ETDEWEB)

    King, Bruce A.; Patankar, Kshitish A.; Costeux, Stephane; Jeon, Hyun K.

    2017-01-17

    A polymeric foam article with a polymer matrix defining multiple cells therein has a polymer component with a first polymer that is a polyhedral oligomeric silsesquioxane grafted polymer that has a weight-average molecular weight of two kilograms per mole or higher and 200 kilograms per mole or lower.

  11. Polyhedral oligomeric silsesquioxane grafted polymer in polymeric foam

    Science.gov (United States)

    King, Bruce A.; Patankar, Kshitish A.; Costeux, Stephane; Jeon, Hyun K.

    2017-01-17

    A polymeric foam article with a polymer matrix defining multiple cells therein has a polymer component with a first polymer that is a polyhedral oligomeric silsesquioxane grafted polymer that has a weight-average molecular weight of two kilograms per mole or higher and 200 kilograms per mole or lower.

  12. High Content Analysis of Compositional Heterogeneities to Study GPCR Oligomerization

    DEFF Research Database (Denmark)

    Walsh, Samuel McEwen

    In this thesis I demonstrate how the natural compositional heterogeneities of synthetic and living cell model systems can be used to quantitate the mechanics of G-protein coupled receptor (GPCR) oligomerization with Förster resonance energy transfer (FRET). The thesis is structured around three a...

  13. Multi-PAS domain-mediated protein oligomerization of PpsR from Rhodobacter sphaeroides

    Energy Technology Data Exchange (ETDEWEB)

    Heintz, Udo; Meinhart, Anton; Winkler, Andreas, E-mail: andreas.winkler@mpimf-heidelberg.mpg.de [Max Planck Institute for Medical Research, Heidelberg (Germany)

    2014-03-01

    Crystal structures of two truncated variants of the transcription factor PpsR from R. sphaeroides are presented that enabled the phasing of a triple PAS domain construct. Together, these structures reveal the importance of α-helical PAS extensions for multi-PAS domain-mediated protein oligomerization and function. Per–ARNT–Sim (PAS) domains are essential modules of many multi-domain signalling proteins that mediate protein interaction and/or sense environmental stimuli. Frequently, multiple PAS domains are present within single polypeptide chains, where their interplay is required for protein function. Although many isolated PAS domain structures have been reported over the last decades, only a few structures of multi-PAS proteins are known. Therefore, the molecular mechanism of multi-PAS domain-mediated protein oligomerization and function is poorly understood. The transcription factor PpsR from Rhodobacter sphaeroides is such a multi-PAS domain protein that, in addition to its three PAS domains, contains a glutamine-rich linker and a C-terminal helix–turn–helix DNA-binding motif. Here, crystal structures of two N-terminally and C-terminally truncated PpsR variants that comprise a single (PpsR{sub Q-PAS1}) and two (PpsR{sub N-Q-PAS1}) PAS domains, respectively, are presented and the multi-step strategy required for the phasing of a triple PAS domain construct (PpsR{sub ΔHTH}) is illustrated. While parts of the biologically relevant dimerization interface can already be observed in the two shorter constructs, the PpsR{sub ΔHTH} structure reveals how three PAS domains enable the formation of multiple oligomeric states (dimer, tetramer and octamer), highlighting that not only the PAS cores but also their α-helical extensions are essential for protein oligomerization. The results demonstrate that the long helical glutamine-rich linker of PpsR results from a direct fusion of the N-cap of the PAS1 domain with the C-terminal extension of the N-domain that

  14. Playing Possum

    Directory of Open Access Journals (Sweden)

    Enrico Euli

    2016-07-01

    Full Text Available Our society is drenched in the catastrophe; where the growth of financial crisis, environmental cataclysm and militarization represents its gaudiest and mortifying phenomena. Humans struggle with depression, sense of impotence, anguish towards a future considered a threat.  A possibility to keep us alive can be represented by the enhancement of our ability in ‘playing Possum’, an exercise of desisting and renitence: to firmly say ‘no’. To say no to a world that proposes just one way of being and living free, that imposes as the only unavoidable possible destiny.

  15. Playful Technology

    DEFF Research Database (Denmark)

    Johansen, Stine Liv; Eriksson, Eva

    2013-01-01

    In this paper, the design of future services for children in Danish public libraries is discussed, in the light of new challenges and opportunities in relation to new media and technologies. The Danish government has over the last few years initiated and described a range of initiatives regarding...... in the library, the changing role of the librarians and the library space. We argue that intertwining traditional library services with new media forms and engaging play is the core challenge for future design in physical public libraries, but also that it is through new media and technology that new...

  16. Playful Technology

    DEFF Research Database (Denmark)

    Johansen, Stine Liv; Eriksson, Eva

    2013-01-01

    in the library, the changing role of the librarians and the library space. We argue that intertwining traditional library services with new media forms and engaging play is the core challenge for future design in physical public libraries, but also that it is through new media and technology that new......In this paper, the design of future services for children in Danish public libraries is discussed, in the light of new challenges and opportunities in relation to new media and technologies. The Danish government has over the last few years initiated and described a range of initiatives regarding...

  17. Oligomeric structure of the MALT1 tandem Ig-like domains.

    Directory of Open Access Journals (Sweden)

    Liyan Qiu

    Full Text Available BACKGROUND: Mucosa-associated lymphoid tissue 1 (MALT1 plays an important role in the adaptive immune program. During TCR- or BCR-induced NF-κB activation, MALT1 serves to mediate the activation of the IKK (IκB kinase complex, which subsequently regulates the activation of NF-κB. Aggregation of MALT1 is important for E3 ligase activation and NF-κB signaling. PRINCIPAL FINDINGS: Unlike the isolated CARD or paracaspase domains, which behave as monomers, the tandem Ig-like domains of MALT1 exists as a mixture of dimer and tetramer in solution. High-resolution structures reveals a protein-protein interface that is stabilized by a buried surface area of 1256 Å(2 and contains numerous hydrogen and salt bonds. In conjunction with a second interface, these interactions may represent the basis of MALT1 oligomerization. CONCLUSIONS: The crystal structure of the tandem Ig-like domains reveals the oligomerization potential of MALT1 and a potential intermediate in the activation of the adaptive inflammatory pathway. ENHANCED VERSION: This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the web plugin are available in Text S1.

  18. Oligomerization states of Bowman-Birk inhibitor by atomic force microscopy and computational approaches.

    Science.gov (United States)

    Silva, Luciano P; Azevedo, Ricardo B; Morais, Paulo C; Ventura, Manuel M; Freitas, Sonia M

    2005-11-15

    Several methods have been applied to study protein-protein interaction from structural and thermodynamic point of view. The present study reveals that atomic force microscopy (AFM), molecular modeling, and docking approaches represent alternative methods offering new strategy to investigate structural aspects in oligomerization process of proteinase inhibitors. The topography of the black-eyed pea trypsin/chymotrypsin inhibitor (BTCI) was recorded by AFM and compared with computational rigid-bodies docking approaches. Multimeric states of BTCI identified from AFM analysis showed globular-ellipsoidal shapes. Monomers, dimers, trimers, and hexamers were the most prominent molecular arrays observed in AFM images as evaluated by molecular volume calculations and corroborated by in silico docking and theoretical approaches. We therefore propose that BTCI adopts stable and well-packed self-assembled states in monomer-dimer-trimer-hexamer equilibrium. Although there are no correlation between specificity and packing efficiency among proteinases and proteinase inhibitors, the AFM and docked BTCI analyses suggest that these assemblies may exist in situ to play their potential function in oligomerization process.

  19. Evolutionary trace-based peptides identify a novel asymmetric interaction that mediates oligomerization in nuclear receptors.

    Science.gov (United States)

    Gu, Peili; Morgan, Daniel H; Sattar, Minawar; Xu, Xueping; Wagner, Ryan; Raviscioni, Michele; Lichtarge, Olivier; Cooney, Austin J

    2005-09-01

    Germ cell nuclear factor (GCNF) is an orphan nuclear receptor that plays important roles in development and reproduction, by repressing the expression of essential genes such as Oct4, GDF9, and BMP15, through binding to DR0 elements. Surprisingly, whereas recombinant GCNF binds to DR0 sequences as a homodimer, endogenous GCNF does not exist as a homodimer but rather as part of a large complex termed the transiently retinoid-induced factor (TRIF). Here, we use evolutionary trace (ET) analysis to design mutations and peptides that probe the molecular basis for the formation of this unusual complex. We find that GCNF homodimerization and TRIF complex formation are DNA-dependent, and ET suggests that dimerization involves key functional sites on both helix 3 and helix 11, which are located on opposing surfaces of the ligand binding domain. Targeted mutations in either helix of GCNF disrupt the formation of both the homodimer and the endogenous TRIF complex. Moreover, peptide mimetics of both of these ET-determined sites inhibit dimerization and TRIF complex formation. This suggests that a novel helix 3-helix 11 heterotypic interaction mediates GCNF interaction and would facilitate oligomerization. Indeed, it was determined that the endogenous TRIF complex is composed of a GCNF oligomer. These findings shed light on an evolutionarily selected mechanism that reveals the unusual DNA-binding, dimerization, and oligomerization properties of GCNF.

  20. Phosphate and HEPES buffers potently affect the fibrillation and oligomerization mechanism of Alzheimer's Aβ peptide.

    Science.gov (United States)

    Garvey, Megan; Tepper, Katharina; Haupt, Caroline; Knüpfer, Uwe; Klement, Karolin; Meinhardt, Jessica; Horn, Uwe; Balbach, Jochen; Fändrich, Marcus

    2011-06-10

    The oligomerization of Aβ peptide into amyloid fibrils is a hallmark of Alzheimer's disease. Due to its biological relevance, phosphate is the most commonly used buffer system for studying the formation of Aβ and other amyloid fibrils. Investigation into the characteristics and formation of amyloid fibrils frequently relies upon material formed in vitro, predominantly in phosphate buffers. Herein, we examine the effects on the fibrillation and oligomerization mechanism of Aβ peptide that occur due solely to the influence of phosphate buffer. We reveal that significant differences in amyloid fibrillation are observed due to fibrillation being initiated in phosphate or HEPES buffer (at physiological pH and temperature). Except for the differing buffer ions, all experimental parameters were kept constant. Fibril formation was assessed using fluorescently monitored kinetic studies, microscopy, X-ray fiber diffraction and infrared and nuclear magnetic resonance spectroscopies. Based on this set up, we herein reveal profound effects on the mechanism and speed of Aβ fibrillation. The three histidine residues at positions 6, 13 and 14 of Aβ(1-40) are instrumental in these mechanistic changes. We conclude that buffer plays a more significant role in fibril formation than has been generally acknowledged.

  1. Playing cards.

    Science.gov (United States)

    1977-01-01

    Mrs. Zahia Marzouk, vice-president of the Alexandria Family Planning Association and a living legend of Egyptian family planning, does not believe in talking about problems. She is far too busy learning from people and teaching them. Her latest brainstorm is a set of playing cards designed to help girls and women to read and learn about family planning at the same time. The 5 packs of cards, representing familiar words and sounds, and each with a family planning joker, took Mrs. Marzouk 6 months to design and paint by hand. They have now been printed, packed into packets provided by UNICEF, and distributed to some 2000 literacy groups in factories and family planning clinics. Each woman who succeeds in learning to read is encouraged to teach 4 others. They then go to the family planning clinic to be examined and gain a certificate. For the teacher who has made them proficient there is a special prize. Girls at El Brinth village outside Alexandria are pictured playing cards at the family planning center where they are learning various skills including how to read.

  2. Crystal Structure of the Marburg Virus VP35 Oligomerization Domain

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, Jessica F.; Kirchdoerfer, Robert N.; Urata, Sarah M.; Li, Sheng; Tickle, Ian J.; Bricogne, Gérard; Saphire, Erica Ollmann (Scripps); (Globel Phasing); (UCSD)

    2016-11-09

    ABSTRACT

    Marburg virus (MARV) is a highly pathogenic filovirus that is classified in a genus distinct from that of Ebola virus (EBOV) (generaMarburgvirusandEbolavirus, respectively). Both viruses produce a multifunctional protein termed VP35, which acts as a polymerase cofactor, a viral protein chaperone, and an antagonist of the innate immune response. VP35 contains a central oligomerization domain with a predicted coiled-coil motif. This domain has been shown to be essential for RNA polymerase function. Here we present crystal structures of the MARV VP35 oligomerization domain. These structures and accompanying biophysical characterization suggest that MARV VP35 is a trimer. In contrast, EBOV VP35 is likely a tetramer in solution. Differences in the oligomeric state of this protein may explain mechanistic differences in replication and immune evasion observed for MARV and EBOV.

    IMPORTANCEMarburg virus can cause severe disease, with up to 90% human lethality. Its genome is concise, only producing seven proteins. One of the proteins, VP35, is essential for replication of the viral genome and for evasion of host immune responses. VP35 oligomerizes (self-assembles) in order to function, yet the structure by which it assembles has not been visualized. Here we present two crystal structures of this oligomerization domain. In both structures, three copies of VP35 twist about each other to form a coiled coil. This trimeric assembly is in contrast to tetrameric predictions for VP35 of Ebola virus and to known structures of homologous proteins in the measles, mumps, and Nipah viruses. Distinct oligomeric states of the Marburg and Ebola virus VP35 proteins may explain differences between them in polymerase function and immune evasion. These findings may provide a more accurate understanding of the

  3. Preparative isolation of oligomeric procyanidins from Hawthorn (Crataegus spp.).

    Science.gov (United States)

    Zumdick, S; Petereit, F; Luftmann, H; Hensel, A

    2009-04-01

    The oligomeric procyanidins (OPC) from Hawthorn leaves and flowers (Crataegi folium cum flore) are considered to be in part responsible for the cardiotonic clinical activity of the herbal material. Effective methods for rapid isolation of these heterogenous oligomeric clusters with defined molecular weight as reference compounds are not published until now. Therefore the water soluble fraction of an acetone/water (7 + 3) extract of Hawthorn leaves and flowers was fractionated by a combination of MPLC on RP-18 material and preparative HPLC using a diol stationary phase. This procedure resulted in the effective isolation of procyanidins with a distinct degree of polymerization (DP) from dimers DP2 up to tridecamers DP13. Exact mass measurements with negative ESI-TOF/MS were employed to confirm the respective structures of the isolated procyanidins.

  4. Electron Microscopy Structural Insights into CPAP Oligomeric Behavior

    DEFF Research Database (Denmark)

    Alvarez-Cabrera, Ana L; Delgado, Sandra; Gil-Carton, David

    2017-01-01

    that represent obtaining the protein in a soluble, homogeneous state for structural studies. Our work constitutes a systematic structural analysis on multiple oligomers of HsCPAP(897)(-1338), using single-particle electron microscopy (EM) of negatively stained (NS) samples. Based on image classification...... into clearly different regular 3D maps (putatively corresponding to dimers and tetramers) and direct observation of individual images representing other complexes of HsCPAP(897-1338) (i.e., putative flexible monomers and higher-order multimers), we report a dynamic oligomeric behavior of this protein, where...... of atomic models into the NS 3D maps at resolutions around 20 Å is performed only to complement our experimental data, allowing us to hypothesize on the oligomeric composition of the different complexes. In this way, the current EM work represents an initial step toward the structural characterization...

  5. Dissecting functions of the conserved oligomeric Golgi tethering complex using a cell-free assay.

    Science.gov (United States)

    Cottam, Nathanael P; Wilson, Katherine M; Ng, Bobby G; Körner, Christian; Freeze, Hudson H; Ungar, Daniel

    2014-01-01

    Vesicle transport sorts proteins between compartments and is thereby responsible for generating the non-uniform protein distribution along the eukaryotic secretory and endocytic pathways. The mechanistic details of specific vesicle targeting are not yet well characterized at the molecular level. We have developed a cell-free assay that reconstitutes vesicle targeting utilizing the recycling of resident enzymes within the Golgi apparatus. The assay has physiological properties, and could be used to show that the two lobes of the conserved oligomeric Golgi tethering complex play antagonistic roles in trans-Golgi vesicle targeting. Moreover, we can show that the assay is sensitive to several different congenital defects that disrupt Golgi function and therefore cause glycosylation disorders. Consequently, this assay will allow mechanistic insight into the targeting step of vesicle transport at the Golgi, and could also be useful for characterizing some novel cases of congenital glycosylation disorders.

  6. Inhibition of listeriolysin O oligomerization by lutein prevents Listeria monocytogenes infection.

    Science.gov (United States)

    Liu, Bowen; Teng, Zihao; Wang, Jianfeng; Lu, Gejin; Deng, Xuming; Li, Li

    2017-01-01

    The foodborne pathogenic bacterial species Listeria monocytogenes (L. monocytogenes) has caused incalculable damages to public health, and its successful infection requires various virulence factors, including Listeriolysin O (LLO). By forming pores in phagosomal membranes and even in some organelles, LLO plays an indispensable role in the ability of L. monocytogenes to escape from host immune attacks. Because of its critical role, LLO offers an appropriate therapeutic target against L. monocytogenes infection. Here, lutein, a natural small molecule existing widely in fruits and vegetables, is demonstrated as an effective inhibitor of LLO that works by blocking its oligomerization during invasion without showing significant bacteriostatic activity. Further assays applying lutein in cell culture models of invasion and in animal models showed that lutein could effectively inhibit L. monocytogenes infection. Overall, our results indicate that lutein may represent a promising and novel therapeutic agent against L. monocytogenes infection. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Pharmacological Profiles of Oligomerized μ-Opioid Receptors

    OpenAIRE

    Ing-Kang Ho; Cynthia Wei-Sheng Lee

    2013-01-01

    Opioids are widely prescribed pain relievers with multiple side effects and potential complications. They produce analgesia via G-protein-protein coupled receptors: μ-, δ-, κ-opioid and opioid receptor-like 1 receptors. Bivalent ligands targeted to the oligomerized opioid receptors might be the key to developing analgesics without undesired side effects and obtaining effective treatment for opioid addicts. In this review we will update the biological effects of μ-opioids on homo- or hetero-ol...

  8. Receptor Oligomerization as a Process Modulating Cellular Semiotics

    DEFF Research Database (Denmark)

    Giorgi, Franco; Bruni, Luis Emilio; Maggio, Roberto

    2010-01-01

    The majority of G protein-coupled receptors (GPCRs) self-assemble in the form dimeric/oligomeric complexes along the plasma membrane. Due to the molecular interactions they participate, GPCRs can potentially provide the framework for discriminating a wide variety of intercellular signals, as based...... and degeneracy may appear as the required feature to integrate the cell system into functional units of progressively higher hierarchical levels....

  9. DNA display of glycoconjugates to emulate oligomeric interactions of glycans

    Directory of Open Access Journals (Sweden)

    Alexandre Novoa

    2015-05-01

    Full Text Available Glycans (carbohydrate portion of glycoproteins and glycolipids frequently exert their function through oligomeric interactions involving multiple carbohydrate units. In efforts to recapitulate the diverse spatial arrangements of the carbohydrate units, assemblies based on hybridization of nucleic acid conjugates have been used to display simplified ligands with tailored interligand distances and valences. The programmability of the assemblies lends itself to a combinatorial display of multiple ligands. Recent efforts in the synthesis and applications of such conjugates are discussed.

  10. Copper-induced oligomerization of peptides: a model study.

    Science.gov (United States)

    Schlosser, Gitta; Stefanescu, Raluca; Przybylski, Michael; Murariu, Manuela; Hudecz, Ferenc; Drochioiu, Gabi

    2007-01-01

    In this work, copper-binding of the tetraglycine peptide (Gly-Gly-Gly-Gly) was studied by electrospray ionization mass spectrometry. Experiments were performed under alkaline conditions, in the presence of ethanolamine (pH 10.95). We observed that the presence of copper(II) ions induces the aggregation of the peptide and the formation of copper-bound complexes with higher molecular mass is favored, such as the oligomer complexes [3M+2Cu-3H](+) and [4M+3Cu-5H](+). At 1:1 peptide-copper(II) ion ratio, the singly charged [3M+2Cu-3H](+) oligomer complex is the base peak in the mass spectrum. Metal ion-induced oligomer-ization of neurotoxic peptides is well known in the literature; however, there are very few examples in which such oligomerization was directly observed by mass spectrometry. Our results show that application of short peptides can be useful to study the -mechanism of metal ion binding and metal ion-induced oligomerization of peptides.

  11. Functional Perfluoroalkyl Polyhedral Oligomeric Silsesquioxane (F-POSS): Building Blocks for Low Surface Energy Materials

    Science.gov (United States)

    2010-10-21

    Technical Paper 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Functional Perfluoroalkyl Polyhedral Oligomeric Silsesquioxane (F...long chain fluorinated alkyl groups ranging from 6-12 carbon atoms in length. Herein, a disilanol perfluoroalkyl polyhedral oligomeric...FUNCTIONAL PERFLUOROALKYL POLYHEDRAL OLIGOMERIC SILSESQUIOXANES (F-POSS): BUILDING BLOCKS FOR LOW SURFACE ENERGY MATERIA LS Sean M Rami,.e:, Yvonne Dia

  12. hA molecular switch in amyloid assembly: Met35 and amyloid beta-protein oligomerization

    OpenAIRE

    Bitan, Gal; Tarus, Bogdan; Vollers, Sabrina S.; Lashuel, Hilal A.; Condron, Margaret M.; Straub, John E.; Teplow, David B.

    2003-01-01

    Aberrant protein oligomerization is an important pathogenetic process in vivo. In Alzheimer's disease (AD), the amyloid beta-protein (Abeta) forms neurotoxic oligomers. The predominant in vivo Abeta alloforms, Abeta40 and Abeta42, have distinct oligomerization pathways. Abeta42 monomers oligomerize into pentamer/hexamer units (paranuclei) which self-associate to form larger oligomers. Abeta40 does not form these paranuclei, a fact which may explain the particularly strong linkage of Abeta42 w...

  13. Expression and effect of proline hydroxylase domain 2 in retina of diabetic rats

    Directory of Open Access Journals (Sweden)

    Zhen Li

    2016-03-01

    Full Text Available AIM: To observe the expression of proline hydroxylase domain 2 (PHD2 in the retina of diabetic rats and investigate the relationship between PHD2 and relevant intraocular vascular proliferation factors. METHODS: Sixty male specific pathogen free (SPF Sprague-Dawley (SD rats were randomly divided into two groups: the diabetic group and the control group. The rats in the diabetic group were intraperitoneally injected with 60 mg/kg (0.60 mL/100g of streptozotocin to induce a diabetic rat model. The rats in the control group were injected with an equal volume of sodium citrate buffer solution by the same method. Hematoxylin-eosin (HE staining and immumofluorescence (IF method were adopted to observe the pathological changes of retinal tissues and the expression of PHD2, glial fibrillary acidic protein (GFAP, vascular endothelial growth factor (VEGF by 8wk. RT-PCR method was applied to detect the expressions of mRNA of PHD2, VEGF and GFAP. The relationship between PHD2 and other vascular proliferation factors was analyzed. RESULTS: HE staining showed that there was the retinal tissue edema in the diabetic group, and the arrangement was in disorder, and proliferation could be seen. IF staining: in the retina of normal rats, PHD2 was not expressed, GFAP and VEGF were mainly expressed in astrocytes; while in the diabetic rats, PHD2, GFAP and VEGF staining showed strong positivity in all retinal layers, mainly in neurogliocytes. PHD2 was co-expressed with VEGF and GFAP. The mRNA expression levels of PHD2, GFAP and VEGF in the diabetic group were obviously higher than that in the control group,respectively 1.83 times, 1.75 times and 2.08 times. The difference had statistical significance (P<0.01. CONCLUSION: The high expression of PHD2 in the retina of early-stage diabetic rats might result from secretion of neurogliocytes induced by local high-concentration blood glucose, thus promoting the expression of VEGF and GFAP. PHD2 plays an important role during

  14. Radical mechanisms of methyl vinyl ketone oligomerization through aqueous phase OH-oxidation: on the paradoxical role of dissolved molecular oxygen

    Directory of Open Access Journals (Sweden)

    P. Renard

    2013-01-01

    Full Text Available It is now accepted that one of the important pathways of Secondary Organic Aerosol (SOA formation occurs through aqueous phase chemistry in the atmosphere. However, the liquid phase chemical mechanisms leading to macromolecules are still not well understood. For α-dicarbonyl precursors, such as methylglyoxal and glyoxal, radical reactions through OH-oxidation produce oligomers, irreversibly and faster than accretion reactions. Methyl vinyl ketone (MVK was chosen in the present study as it is an α, β-unsaturated carbonyl that can undergo such reaction pathways in the aqueous phase and forms even high molecular weight oligomers. We present here experiments on the aqueous phase OH-oxidation of MVK, performed under atmospheric relevant conditions. Using NMR and UV absorption spectroscopy, high and ultra-high resolution mass spectrometry, we show that the fast formation of oligomers up to 1800 Da is due to radical oligomerization of MVK, and 13 series of oligomers (out of a total of 26 series are identified. The influence of atmospherically relevant parameters such as temperature, initial concentrations of MVK and dissolved oxygen are presented and discussed. In agreement with the experimental observations, we propose a chemical mechanism of OH-oxidation of MVK in the aqueous phase that proceeds via radical oligomerization of MVK on the olefin part of the molecule. This mechanism highlights the paradoxical role of dissolved O2: while it inhibits oligomerization reactions, it contributes to produce oligomerization initiator radicals, which rapidly consume O2, thus leading to the supremacy of oligomerization reactions after several minutes of reaction. These processes, together with the large ranges of initial concentrations investigated (60–656 μM of dissolved O2 and 0.2–20 mM of MVK show the fundamental role that O2 likely plays in atmospheric organic aerosol.

  15. Quaternary Structure Analyses of an Essential Oligomeric Enzyme.

    Science.gov (United States)

    Soares da Costa, Tatiana P; Christensen, Janni B; Desbois, Sebastien; Gordon, Shane E; Gupta, Ruchi; Hogan, Campbell J; Nelson, Tao G; Downton, Matthew T; Gardhi, Chamodi K; Abbott, Belinda M; Wagner, John; Panjikar, Santosh; Perugini, Matthew A

    2015-01-01

    Here, we review recent studies aimed at defining the importance of quaternary structure to a model oligomeric enzyme, dihydrodipicolinate synthase. This will illustrate the complementary and synergistic outcomes of coupling the techniques of analytical ultracentrifugation with enzyme kinetics, in vitro mutagenesis, macromolecular crystallography, small angle X-ray scattering, and molecular dynamics simulations, to demonstrate the role of subunit self-association in facilitating protein dynamics and enzyme function. This multitechnique approach has yielded new insights into the molecular evolution of protein quaternary structure.

  16. Spontaneous Oligomerization of Nucleotide Alternatives in Aqueous Solutions

    Science.gov (United States)

    Smith, Karen E.; House, Christopher H.; Dworkin, Jason P.; Callahan, Michael P.

    2017-03-01

    On early Earth, a primitive polymer that could spontaneously form from likely available precursors may have preceded both RNA and DNA as the first genetic material. Here, we report that heated aqueous solutions containing 5-hydroxymethyluracil (HMU) result in oligomers of uracil, heated solutions containing 5-hydroxymethylcytosine (HMC) result in oligomers of cytosine, and heated solutions containing both HMU and HMC result in mixed oligomers of uracil and cytosine. Oligomerization of hydroxymethylated pyrimidines, which may have been abundant on the primitive Earth, might have been important in the development of simple informational polymers.

  17. Characterization of oligomeric forms from mammalian F0F1ATP synthase by BN-PAGE: the role of detergents.

    Science.gov (United States)

    Bisetto, Elena; Giorgio, Valentina; Di Pancrazio, Francesca; Mavelli, Irene; Lippe, Giovanna

    2007-12-01

    It is now widely accepted that F0F1ATPsynthase is present in membrane, beside as monomers, in homo-dimeric and higher homo-oligomeric forms, which probably play critical roles in determining mitochondrial morphology. One-step mild detergent extraction followed by blue native electrophoresis (BN-PAGE) is a very interesting tool for studying the native membrane protein assemblies which can be associated with second/third-dimensional SDS-PAGE, immunoblotting, in-gel enzyme activity staining and mass spectrometry analyses. By combining these techniques, we resolved monomers and higher oligomeric forms of ATPsynthase from bovine heart mitochondria. However, a critical point is the choice of the detergents, which strongly influence the protein pattern of BN-PAGE. By using Triton X-100 we obtained that, in spite of the same subunit composition, monomers have a much lower specific activity than dimers and the two forms have a different pattern of tyrosine phosphorylation, suggesting that monomers and dimers are functionally distinct in membrane. In addition, enzyme self-association appeared to occur independently from the binding to ATPsynthase of the inhibitor protein IF1. Dodecylmaltoside was optimal to extract the enzyme from single biopsy samples, allowing us to demonstrate that IF1 plays a central role in regulating the enzyme activity in heart in vivo. Only low concentration of digitonin maintained significant amounts of ATPsynthase oligomers, which seemed to retain intact their native catalytic properties.

  18. Reaction Mechanisms of the Initial Oligomerization of Aluminophosphate.

    Science.gov (United States)

    Xiang, Yan; Xin, Liang; Deetz, Joshua D; Sun, Huai

    2016-05-12

    The mechanisms of aluminophosphate oligomerization were investigated using density functional theory with the SMD solvation model. Two aluminum species, Al(OH)4(-) and Al(H2O)6(3+), and four phosphorus species, H3PO4, H2PO4(-), HPO4(2-), and PO4(3-), were considered as the monomers for polycondensation reactions. It was found that the most favorable pathway to dimerization was a Lewis acid-base reaction: the aprotic oxygen of phosphoric acid (P═O) performs a nucleophilic attack on the central aluminum atom of Al(OH)4(-). Using this mechanism as a pattern, plausible dimerization mechanisms were investigated by varying the proticity and hydration of the phosphorus and aluminum monomers, respectively. The relative reaction rates of each mechanism were estimated under different pH conditions. The chain growth of aluminophosphates to trimers, tetramers, and pentamers and the cyclization of a linear tetramer were also investigated. For oligomerization reactions beyond dimer formation, it is found that cluster growth favors the addition of the phosphoric monomers rather than aluminum monomers.

  19. The oligomeric state of the active Vps4 AAA ATPase

    Science.gov (United States)

    Monroe, Nicole; Han, Han; Gonciarz, Malgorzata D.; Eckert, Debra M.; Karren, Mary Anne; Whitby, Frank G.; Sundquist, Wesley I.; Hill, Christopher P.

    2013-01-01

    The cellular ESCRT pathway drives membrane constriction toward the cytosol and effects membrane fission during cytokinesis, endosomal sorting, and the release of many enveloped viruses, including HIV. A component of this pathway, the AAA ATPase Vps4, provides energy for pathway progression. Although it is established that Vps4 functions as an oligomer, subunit stoichiometry and other fundamental features of the functional enzyme are unclear. Higher-order oligomers have thus far only been characterized for a Walker B mutant of Vps4 in the presence of ATP. Here, we report that although some mutant Vps4 proteins form dodecameric assemblies, active wild-type S. cerevisiae and S. solfataricus Vps4 enzymes can form hexamers in the presence of ATP and ADP, as assayed by size exclusion chromatography and equilibrium analytical ultracentifugation. The Vta1p activator binds hexameric yeast Vps4p without changing the oligomeric state of Vps4p, implying that the active Vta1p:Vps4p complex also contains a single hexameric ring. Additionally, we report crystal structures of two different archaeal Vps4 homologs, whose structures and lattice interactions suggest a conserved mode of oligomerization. Disruption of the proposed hexamerization interface by mutagenesis abolished the ATPase activity of archaeal Vps4 proteins and blocked Vps4p function in S. cerevisiae. These data challenge the prevailing model that active Vps4 is a double ring dodecamer, and argue that, like other type I AAA ATPases, Vps4 functions as a single ring with six subunits. PMID:24161953

  20. Structure-based molecular modeling approaches to GPCR oligomerization.

    Science.gov (United States)

    Kaczor, Agnieszka A; Selent, Jana; Poso, Antti

    2013-01-01

    Classical structure-based drug design techniques using G-protein-coupled receptors (GPCRs) as targets focus nearly exclusively on binding at the orthosteric site of a single receptor. Dimerization and oligomerization of GPCRs, proposed almost 30 years ago, have, however, crucial relevance for drug design. Targeting these complexes selectively or designing small molecules that affect receptor-receptor interactions might provide new opportunities for novel drug discovery. In order to study the mechanisms and dynamics that rule GPCRs oligomerization, it is essential to understand the dynamic process of receptor-receptor association and to identify regions that are suitable for selective drug binding, which may be determined with experimental methods such as Förster resonance energy transfer (FRET) or Bioluminescence resonance energy transfer (BRET) and computational sequence- and structure-based approaches. The aim of this chapter is to provide a comprehensive description of the structure-based molecular modeling methods for studying GPCR dimerization, that is, protein-protein docking, molecular dynamics, normal mode analysis, and electrostatics studies.

  1. Modulation of Innate Immune Signalling by Lipid-Mediated MAVS Transmembrane Domain Oligomerization.

    Directory of Open Access Journals (Sweden)

    Luis Nobre

    Full Text Available RIG-I-like receptors detect viral RNA in infected cells and promote oligomerization of the outer mitochondrial membrane protein MAVS to induce innate immunity to viral infection through type I interferon production. Mitochondrial reactive oxygen species (mROS have been shown to enhance anti-viral MAVS signalling, but the mechanisms have remained obscure. Using a biochemical oligomerization-reporter fused to the transmembrane domain of MAVS, we found that mROS inducers promoted lipid-dependent MAVS transmembrane domain oligomerization in the plane of the outer mitochondrial membrane. These events were mirrored by Sendai virus infection, which similarly induced lipid peroxidation and promoted lipid-dependent MAVS transmembrane domain oligomerization. Our observations point to a role for mROS-induced changes in lipid bilayer properties in modulating antiviral innate signalling by favouring the oligomerization of MAVS transmembrane domain in the outer-mitochondrial membrane.

  2. Effect of leaving group on the oligomerization of 5'-AMP on montmorillonite. [Abstract only

    Science.gov (United States)

    Prabahar, K. Joseph; Ferris, James P.

    1994-01-01

    The oligomerization of imidazole derivative of 5'-AMP (ImpA) in the presence of montmorillonite clay yields oligomers containing up to 10 monomer units. In these reactions, the heterocyclic base, imidazole is the leaving group. In our present study, we synthesized a series of activated nucleotides of 5'AMP using other leaving groups such as pyrazole, 1,2,4-triazole, piperidine, morpholine, 4-aminopyridine, 4-methylaminopyridine, 4-dimethylaminopyridine, 2-aminobenzimidazole etc. to determine the effect of amine leaving group on the products of the oligomerization reaction. Earlier results from our laboratory showed that the presence AppA in the clay reaction of ImpA enhances the oligomerization reaction to yield higher oligomers. We also studied the effect of AppA in the clay mediated oligomerization reaction of the activated nucleotides. Oligomerization of 2-amino-benzimidazole derivative of 5'-AMP gave higher oligomers containing up to nine monomer units in the presence of AppA.

  3. 40 CFR 721.3100 - Oligomeric silicic acid ester compound with a hy-droxyl-al-kyla-mine.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Oligomeric silicic acid ester compound... Significant New Uses for Specific Chemical Substances § 721.3100 Oligomeric silicic acid ester compound with a... chemical substance identified generically as oligomeric silicic acid ester compound with...

  4. Antioxidant activity of oligomeric acylphloroglucinols from Myrtus communis L.

    Science.gov (United States)

    Rosa, Antonella; Deiana, Monica; Casu, Viviana; Corona, Giulia; Appendino, Giovanni; Bianchi, Federica; Ballero, Mauro; Dessì, M Assunta

    2003-09-01

    The use of myrtle (Myrtus communis L.) as a culinary spice and as a flavoring agent for alcoholic beverages is widespread in the Mediterranean area, and especially in Sardinia. Myrtle contains unique oligomeric non-prenylated acylphloroglucinols, whose antioxidant activity was investigated in various systems. Both semimyrtucommulone (1) and myrtucommulone A (2) showed powerful antioxidant properties, protecting linoleic acid against free radical attack in simple in vitro systems, inhibiting its autoxidation and its FeCl3- and EDTA-mediated oxidation. While both compounds lacked pro-oxidant activity, semimyrtucommulone was more powerful than myrtucommulone A, and was further evaluated in rat liver homogenates for activity against lipid peroxidation induced by ferric-nitrilotriacetate, and in cell cultures for cytotoxicity and the inhibition of TBH- or FeCl3-induced oxidation. The results of these studies established semimyrtucommulone as a novel dietary antioxidant lead.

  5. Green Nanocomposites from Renewable Plant Oils and Polyhedral Oligomeric Silsesquioxanes

    Directory of Open Access Journals (Sweden)

    Takashi Tsujimoto

    2015-06-01

    Full Text Available Green nanocomposites based on renewable plant oils and polyhedral oligomeric silsesquioxanes (POSS have been developed. An acid-catalyzed curing of epoxidized plant oils with oxirane-containing POSS derivatives produced transparent nanocomposite coatings with high gloss surface, in which the organic and inorganic components were linked via covalent bonds. The hardness and mechanical strength were improved by the incorporation of the POSS unit into the organic polymer matrix. Nanostructural analyses of the nanocomposites showed the formation of homogeneous structures at the micrometer scale. On the other hand, such improvements of the coating and mechanical properties were not observed in the composite without covalent bonds between the plant oil-based polymer and POSS unit. The study demonstrates the correlation between the nanostructure of composites and macroscopic properties.

  6. Does oligomerization in fused thiophene affect reactivity and aromaticity?

    Indian Academy of Sciences (India)

    Siddhartha Kr Purkayastha; Pradip Kr Bhattacharyya

    2016-02-01

    Reactivity and aromaticity of a few fused thiophene oligomers and their conformers are discussed in the light of density functional theory (DFT) and conceptual density functional theory. Reactivity parameters, such as hardness () and electrophilicity (), chemical potential () and energy of the HOMO (highest occupied molecular orbital) have been studied. Oligomerization raises the HOMO of the species, which in turn increases the reactivity of the oligomers. The absorption spectra of the species are analysed using TDDFT (time dependent density functional theory). The absorption peaks show red shift with increasing size of the oligomers. Aromaticity of the species is gauged by nucleus independent chemical shift (NICS). The out-of-plane component, (NICSzz) values advocate higher aromatic character at longer distance whereas, NICS supports the reverse.

  7. Cartilage oligomeric matrix protein specific antibodies are pathogenic

    DEFF Research Database (Denmark)

    Geng, Hui; Nandakumar, Kutty Selva; Pramhed, Anna;

    2012-01-01

    ABSTRACT: INTRODUCTION: Cartilage oligomeric matrix protein (COMP) is a major non-collagenous component of cartilage. Earlier, we developed a new mouse model for rheumatoid arthritis using COMP. This study was undertaken to investigate the epitope specificity and immunopathogenicity of COMP...... and the pathogenicity of mAbs was investigated by passive transfer experiments. RESULTS: B cell immunodominant epitopes were localized within 4 antigenic domains of the COMP but with preferential response to the epidermal growth factor (EGF)-like domain. Some of our anti-COMP mAbs showed interactions with the native...... form of COMP, which is present in cartilage and synovium. Passive transfer of COMP-specific mAbs enhanced arthritis when co-administrated with a sub-arthritogenic dose of a mAb specific to collagen type II. Interestingly, we found that a combination of 5 COMP mAbs was capable of inducing arthritis...

  8. Penicillin-binding protein 5 can form a homo-oligomeric complex in the inner membrane of Escherichia coli.

    Science.gov (United States)

    Skoog, Karl; Bruzell, Filippa Stenberg; Ducroux, Aurélie; Hellberg, Mårten; Johansson, Henrik; Lehtiö, Janne; Högbom, Martin; Daley, Daniel O

    2011-09-01

    Penicillin-binding protein 5 (PBP5) is a DD-carboxypeptidase, which cleaves the terminal D-alanine from the muramyl pentapeptide in the peptidoglycan layer of Escherichia coli and other bacteria. In doing so, it varies the substrates for transpeptidation and plays a key role in maintaining cell shape. In this study, we have analyzed the oligomeric state of PBP5 in detergent and in its native environment, the inner membrane. Both approaches indicate that PBP5 exists as a homo-oligomeric complex, most likely as a homo-dimer. As the crystal structure of the soluble domain of PBP5 (i.e., lacking the membrane anchor) shows a monomer, we used our experimental data to generate a model of the homo-dimer. This model extends our understanding of PBP5 function as it suggests how PBP5 can interact with the peptidoglycan layer. It suggests that the stem domains interact and the catalytic domains have freedom to move from the position observed in the crystal structure. This would allow the catalytic domain to have access to pentapeptides at different distances from the membrane. Copyright © 2011 The Protein Society.

  9. Effects of Glycine, Water, Ammonia, and Ammonium Bicarbonate on the Oligomerization of Methionine

    Science.gov (United States)

    Huang, Rui; Furukawa, Yoshihiro; Otake, Tsubasa; Kakegawa, Takeshi

    2017-06-01

    The abiotic oligomerization of amino acids may have created primordial, protein-like biological catalysts on the early Earth. Previous studies have proposed and evaluated the potential of diagenesis for the amino acid oligomerization, simulating the formation of peptides that include glycine, alanine, and valine, separately. However, whether such conditions can promote the formation of peptides composed of multiple amino acids remains unclear. Furthermore, the chemistry of pore water in sediments should affect the oligomerization and degradation of amino acids and oligomers, but these effects have not been studied extensively. In this study, we investigated the effects of water, ammonia, ammonium bicarbonate, pH, and glycine on the oligomerization and degradation of methionine under high pressure (150 MPa) and high temperature conditions (175 °C) for 96 h. Methionine is more difficult to oligomerize than glycine and methionine dimer was formed in the incubation of dry powder of methionine. Methionine oligomers as long as trimers, as well as methionylglycine and glycylmethionine, were formed under every condition with these additional compounds. Among the compounds tested, the oligomerization reaction rate was accelerated by the presence of water and by an increase in pH. Ammonia also increased the oligomerization rate but consumed methionine by side reactions and resulted in the rapid degradation of methionine and its peptides. Similarly, glycine accelerated the oligomerization rate of methionine and the degradation of methionine, producing water, ammonia, and bicarbonate through its decomposition. With Gly, heterogeneous dimers (methionylglycine and glycylmethionine) were formed in greater amounts than with other additional compounds although smaller amount of these heterogeneous dimers were formed with other additional compounds. These results suggest that accelerated reaction rates induced by water and co-existing reactive compounds promote the oligomerization

  10. Effects of Glycine, Water, Ammonia, and Ammonium Bicarbonate on the Oligomerization of Methionine

    Science.gov (United States)

    Huang, Rui; Furukawa, Yoshihiro; Otake, Tsubasa; Kakegawa, Takeshi

    2016-09-01

    The abiotic oligomerization of amino acids may have created primordial, protein-like biological catalysts on the early Earth. Previous studies have proposed and evaluated the potential of diagenesis for the amino acid oligomerization, simulating the formation of peptides that include glycine, alanine, and valine, separately. However, whether such conditions can promote the formation of peptides composed of multiple amino acids remains unclear. Furthermore, the chemistry of pore water in sediments should affect the oligomerization and degradation of amino acids and oligomers, but these effects have not been studied extensively. In this study, we investigated the effects of water, ammonia, ammonium bicarbonate, pH, and glycine on the oligomerization and degradation of methionine under high pressure (150 MPa) and high temperature conditions (175 °C) for 96 h. Methionine is more difficult to oligomerize than glycine and methionine dimer was formed in the incubation of dry powder of methionine. Methionine oligomers as long as trimers, as well as methionylglycine and glycylmethionine, were formed under every condition with these additional compounds. Among the compounds tested, the oligomerization reaction rate was accelerated by the presence of water and by an increase in pH. Ammonia also increased the oligomerization rate but consumed methionine by side reactions and resulted in the rapid degradation of methionine and its peptides. Similarly, glycine accelerated the oligomerization rate of methionine and the degradation of methionine, producing water, ammonia, and bicarbonate through its decomposition. With Gly, heterogeneous dimers (methionylglycine and glycylmethionine) were formed in greater amounts than with other additional compounds although smaller amount of these heterogeneous dimers were formed with other additional compounds. These results suggest that accelerated reaction rates induced by water and co-existing reactive compounds promote the oligomerization

  11. Age- and brain region-dependent α-synuclein oligomerization is attributed to alterations in intrinsic enzymes regulating α-synuclein phosphorylation in aging monkey brains.

    Science.gov (United States)

    Chen, Min; Yang, Weiwei; Li, Xin; Li, Xuran; Wang, Peng; Yue, Feng; Yang, Hui; Chan, Piu; Yu, Shun

    2016-02-23

    We previously reported that the levels of α-syn oligomers, which play pivotal pathogenic roles in age-related Parkinson's disease (PD) and dementia with Lewy bodies, increase heterogeneously in the aging brain. Here, we show that exogenous α-syn incubated with brain extracts from older cynomolgus monkeys and in Lewy body pathology (LBP)-susceptible brain regions (striatum and hippocampus) forms higher amounts of phosphorylated and oligomeric α-syn than that in extracts from younger monkeys and LBP-insusceptible brain regions (cerebellum and occipital cortex). The increased α-syn phosphorylation and oligomerization in the brain extracts from older monkeys and in LBP-susceptible brain regions were associated with higher levels of polo-like kinase 2 (PLK2), an enzyme promoting α-syn phosphorylation, and lower activity of protein phosphatase 2A (PP2A), an enzyme inhibiting α-syn phosphorylation, in these brain extracts. Further, the extent of the age- and brain-dependent increase in α-syn phosphorylation and oligomerization was reduced by inhibition of PLK2 and activation of PP2A. Inversely, phosphorylated α-syn oligomers reduced the activity of PP2A and showed potent cytotoxicity. In addition, the activity of GCase and the levels of ceramide, a product of GCase shown to activate PP2A, were lower in brain extracts from older monkeys and in LBP-susceptible brain regions. Our results suggest a role for altered intrinsic metabolic enzymes in age- and brain region-dependent α-syn oligomerization in aging brains.

  12. DHPC strongly affects the structure and oligomerization propensity of Alzheimer's Aβ(1-40) peptide.

    Science.gov (United States)

    Dahse, Kirsten; Garvey, Megan; Kovermann, Michael; Vogel, Alexander; Balbach, Jochen; Fändrich, Marcus; Fahr, Alfred

    2010-11-05

    Alzheimer's disease (AD) is thought to depend on the deleterious action of amyloid fibrils or oligomers derived from β-amyloid (Aβ) peptide. Out of various known Aβ alloforms, the 40-residue peptide Aβ(1-40) occurs at highest concentrations inside the brains of AD patients. Its aggregation properties critically depend on lipids, and it was thus proposed that lipids could play a major role in AD. To better understand their possible effects on the structure of Aβ and on the ability of this peptide to form potentially detrimental amyloid structures, we here analyze the interactions between Aβ(1-40) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC). DHPC has served, due to its controlled properties, as a major model system for studying general lipid properties. Here, we show that DHPC concentrations of 8 mM or higher exert dramatic effects on the conformation of soluble Aβ(1-40) peptide and induce the formation of β-sheet structure at high levels. By contrast, we find that DHPC concentrations well below the critical micelle concentration present no discernible effect on the conformation of soluble Aβ, although they substantially affect the peptide's oligomerization and fibrillation kinetics. These data imply that subtle lipid-peptide interactions suffice in controlling the overall aggregation properties and drastically accelerate, or delay, the fibrillation kinetics of Aβ peptide in near-physiological buffer solutions.

  13. An integrative approach to the study of filamentous oligomeric assemblies, with application to RecA.

    Science.gov (United States)

    Boyer, Benjamin; Ezelin, Johann; Poulain, Pierre; Saladin, Adrien; Zacharias, Martin; Robert, Charles H; Prévost, Chantal

    2015-01-01

    Oligomeric macromolecules in the cell self-organize into a wide variety of geometrical motifs such as helices, rings or linear filaments. The recombinase proteins involved in homologous recombination present many such assembly motifs. Here, we examine in particular the polymorphic characteristics of RecA, the most studied member of the recombinase family, using an integrative approach that relates local modes of monomer/monomer association to the global architecture of their screw-type organization. In our approach, local modes of association are sampled via docking or Monte Carlo simulations. This enables shedding new light on fiber morphologies that may be adopted by the RecA protein. Two distinct RecA helical morphologies, the so-called "extended" and "compressed" forms, are known to play a role in homologous recombination. We investigate the variability within each form in terms of helical parameters and steric accessibility. We also address possible helical discontinuities in RecA filaments due to multiple monomer-monomer association modes. By relating local interface organization to global filament morphology, the strategies developed here to study RecA self-assembly are particularly well suited to other DNA-binding proteins and to filamentous protein assemblies in general.

  14. The role of Vif oligomerization and RNA chaperone activity in HIV-1 replication.

    Science.gov (United States)

    Batisse, Julien; Guerrero, Santiago; Bernacchi, Serena; Sleiman, Dona; Gabus, Caroline; Darlix, Jean-Luc; Marquet, Roland; Tisné, Carine; Paillart, Jean-Christophe

    2012-11-01

    The viral infectivity factor (Vif) is essential for the productive infection and dissemination of HIV-1 in non-permissive cells that involve most natural HIV-1 target cells. Vif counteracts the packaging of two cellular cytidine deaminases named APOBEC3G (A3G) and A3F by diverse mechanisms including the recruitment of an E3 ubiquitin ligase complex and the proteasomal degradation of A3G/A3F, the inhibition of A3G mRNA translation or by a direct competition mechanism. In addition, Vif appears to be an active partner of the late steps of viral replication by participating in virus assembly and Gag processing, thus regulating the final stage of virion formation notably genomic RNA dimerization and by inhibiting the initiation of reverse transcription. Vif is a small pleiotropic protein with multiple domains, and recent studies highlighted the importance of Vif conformation and flexibility in counteracting A3G and in binding RNA. In this review, we will focus on the oligomerization and RNA chaperone properties of Vif and show that the intrinsic disordered nature of some Vif domains could play an important role in virus assembly and replication. Experimental evidence demonstrating the RNA chaperone activity of Vif will be presented.

  15. An integrative approach to the study of filamentous oligomeric assemblies, with application to RecA.

    Directory of Open Access Journals (Sweden)

    Benjamin Boyer

    Full Text Available Oligomeric macromolecules in the cell self-organize into a wide variety of geometrical motifs such as helices, rings or linear filaments. The recombinase proteins involved in homologous recombination present many such assembly motifs. Here, we examine in particular the polymorphic characteristics of RecA, the most studied member of the recombinase family, using an integrative approach that relates local modes of monomer/monomer association to the global architecture of their screw-type organization. In our approach, local modes of association are sampled via docking or Monte Carlo simulations. This enables shedding new light on fiber morphologies that may be adopted by the RecA protein. Two distinct RecA helical morphologies, the so-called "extended" and "compressed" forms, are known to play a role in homologous recombination. We investigate the variability within each form in terms of helical parameters and steric accessibility. We also address possible helical discontinuities in RecA filaments due to multiple monomer-monomer association modes. By relating local interface organization to global filament morphology, the strategies developed here to study RecA self-assembly are particularly well suited to other DNA-binding proteins and to filamentous protein assemblies in general.

  16. Molecular cloning and functional characterization of duck nucleotide-binding oligomerization domain 1 (NOD1).

    Science.gov (United States)

    Li, Huilin; Jin, Hui; Li, Yaqian; Liu, Dejian; Foda, Mohamed Frahat; Jiang, Yunbo; Luo, Rui

    2017-09-01

    Nucleotide-binding oligomerization domain 1 (NOD1) is an imperative cytoplasmic pattern recognition receptor (PRR) and considered as a key member of the NOD-like receptor (NLR) family which plays a critical role in innate immunity through sensing microbial components derived from bacterial peptidoglycan. In the current study, the full-length of duck NOD1 (duNOD1) cDNA from duck embryo fibroblasts (DEFs) was cloned. Multiple sequence alignment and phylogenetic analysis demonstrated that duNOD1 exhibited a strong evolutionary relationship with chicken and rock pigeon NOD1. Tissue-specific expression analysis showed that duNOD1 was widely distributed in various organs, with the highest expression observed in the liver. Furthermore, duNOD1 overexpression induced NF-κB activation in DEFs and the CARD domain is crucial for duNOD1-mediated NF-κB activation. In addition, silencing the duNOD1 decreased the activity of NF-κB in DEFs stimulated by iE-DAP. Overexpression of duNOD1 significantly increased the expression of TNF-α, IL-6, and RANTES in DEFs. These findings highlight the crucial role of duNOD1 as an intracellular sensor in duck innate immune system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Oligomeric rare-earth metal cluster complexes with endohedral transition metal atoms

    Energy Technology Data Exchange (ETDEWEB)

    Steinberg, Simon; Zimmermann, Sina; Brühmann, Matthias; Meyer, Eva; Rustige, Christian; Wolberg, Marike; Daub, Kathrin; Bell, Thomas; Meyer, Gerd, E-mail: gerd.meyer@uni-koeln.de

    2014-11-15

    Comproportionation reactions of rare-earth metal trihalides (RX{sub 3}) with the respective rare-earth metals (R) and transition metals (T) led to the formation of 22 oligomeric R cluster halides encapsulating T, in 19 cases for the first time. The structures of these compounds were determined by single-crystal X-ray diffraction and are composed of trimers ((T{sub 3}R{sub 11})X{sub 15}-type, P6{sub 3}/m), tetramers ((T{sub 4}R{sub 16})X{sub 28}(R{sub 4}) (P-43m), (T{sub 4}R{sub 16})X{sub 20} (P4{sub 2}/nnm), (T{sub 4}R{sub 16})X{sub 24}(RX{sub 3}){sub 4} (I4{sub 1}/a) and (T{sub 4}R{sub 16})X{sub 23} (C2/m) types of structure) and pentamers ((Ru{sub 5}La{sub 14}){sub 2}Br{sub 39}, Cc) of (TR{sub r}){sub n} (n=2–5) clusters. These oligomers are further enveloped by inner (X{sup i}) as well as outer (X{sup a}) halido ligands, which possess diverse functionalities and interconnect like oligomers through i–i, i–a and/or a–i bridges. The general features of the crystal structures for these new compounds are discussed and compared to literature entries as well as different structure types with oligomeric T centered R clusters. Dimers and tetramers originating from the aggregation of (TR{sub 6}) octahedra via common edges are more frequent than trimers and pentamers, in which the (TR{sub r}) clusters share common faces. - Graphical abstract: Rare earth-metal cluster complexes with endohedral transition metal atoms (TR{sub 6}) may connect via common edges or faces to form dimers, trimers, tetramers and pentamers of which the tetramers are the most prolific. Packing effects and electron counts play an important role. - Highlights: • Rare-earth metal cluster complexes encapsulate transition metal atoms. • Oligomers are built via connection of octahedral clusters via common edges or faces. • Dimers through pentamers with closed structures are known. • Tetramers including a tetrahedron of endohedral atoms are the most prolific.

  18. Transient structural distortion of metal-free Cu/Zn superoxide dismutase triggers aberrant oligomerization

    DEFF Research Database (Denmark)

    Teilum, Kaare; Smith, Melanie H; Schulz, Eike

    2009-01-01

    of the excited-state structure that forms intermolecular contacts in the earliest nonnative dimer/oligomer. The conformational transition that triggers oligomerization is a common feature of WT SOD1 and ALS-associated mutants that have widely different physicochemical properties. But compared with WT SOD1......, the mutants have enhanced structural distortions in their excited states, and in some cases slightly higher excited-state populations and lower kinetic barriers, implying increased susceptibility to oligomerization. Our results provide a unified picture that highlights both (i) a common denominator among......Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease linked to the misfolding of Cu/Zn superoxide dismutase (SOD1). ALS-related defects in SOD1 result in a gain of toxic function that coincides with aberrant oligomerization. The structural events triggering oligomerization have...

  19. Oligomeric protein structure networks: insights into protein-protein interactions

    Directory of Open Access Journals (Sweden)

    Brinda KV

    2005-12-01

    Full Text Available Abstract Background Protein-protein association is essential for a variety of cellular processes and hence a large number of investigations are being carried out to understand the principles of protein-protein interactions. In this study, oligomeric protein structures are viewed from a network perspective to obtain new insights into protein association. Structure graphs of proteins have been constructed from a non-redundant set of protein oligomer crystal structures by considering amino acid residues as nodes and the edges are based on the strength of the non-covalent interactions between the residues. The analysis of such networks has been carried out in terms of amino acid clusters and hubs (highly connected residues with special emphasis to protein interfaces. Results A variety of interactions such as hydrogen bond, salt bridges, aromatic and hydrophobic interactions, which occur at the interfaces are identified in a consolidated manner as amino acid clusters at the interface, from this study. Moreover, the characterization of the highly connected hub-forming residues at the interfaces and their comparison with the hubs from the non-interface regions and the non-hubs in the interface regions show that there is a predominance of charged interactions at the interfaces. Further, strong and weak interfaces are identified on the basis of the interaction strength between amino acid residues and the sizes of the interface clusters, which also show that many protein interfaces are stronger than their monomeric protein cores. The interface strengths evaluated based on the interface clusters and hubs also correlate well with experimentally determined dissociation constants for known complexes. Finally, the interface hubs identified using the present method correlate very well with experimentally determined hotspots in the interfaces of protein complexes obtained from the Alanine Scanning Energetics database (ASEdb. A few predictions of interface hot

  20. Cartilage oligomeric matrix protein in patients with juvenile idiopathic arthritis: relation to growth and disease activity

    DEFF Research Database (Denmark)

    Bjørnhart, Birgitte; Juul, Anders; Nielsen, Susan

    2009-01-01

    OBJECTIVE: Cartilage oligomeric matrix protein (COMP) has been identified as a prognostic marker of progressive joint destruction in rheumatoid arthritis. In this population based study we evaluated associations between plasma concentrations of COMP, disease activity, and growth velocity in patie......OBJECTIVE: Cartilage oligomeric matrix protein (COMP) has been identified as a prognostic marker of progressive joint destruction in rheumatoid arthritis. In this population based study we evaluated associations between plasma concentrations of COMP, disease activity, and growth velocity...

  1. Controlling Protein Oligomerization with Surface Curvature on the Nanoscale

    Science.gov (United States)

    Kurylowicz, Marty; Dutcher, John

    2011-03-01

    We investigate the effect of surface curvature on the conformation of beta-lactoglobulin (β LG) using Single Molecule Force Spectroscopy. β LG is a model interfacial protein which stabilizes oil droplets in milk and is known to undergo structural rearrangement when adsorbed onto a surface. We reliably control nanoscale surface curvature by creating close-packed monolayers of monodisperse polystyrene (PS) nanoparticles with diameters of 20, 40, 60, 80 and 140 nm, which are stable in aqueous buffer. By adsorbing β LG onto these hydrophobic surfaces and collecting force-extension curves in the fluid phase we can compare the conformation of β LG on 5 different surface curvatures with that on a flat PS film. We demonstrate a transition from oligomeric to monomeric β LG as the surface curvature is increased. Histograms of contour length from fits to peaks in the force-extension curves show a single maximum near 30 nm for β LG adsorbed onto nanoparticles with diameters less than 80 nm. For the larger nanoparticles, the histogram approaches that observed for β LG adsorbed onto a flat PS film, with maxima indicative of β LG dimers and trimers.

  2. Polyhedral Oligomeric Silsesquioxane Functionalized Carbon Dots for Cell Imaging.

    Science.gov (United States)

    Wang, Wen-Jing; Hai, Xin; Mao, Quan-Xing; Chen, Ming-Li; Wang, Jian-Hua

    2015-08-05

    In the present study, octa-aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt (OA-POSS) functionalized carbon dots (CDs/POSS) are prepared by a one-pot approach with glycerol as carbon source and solvent medium. OA-POSS serves as a passivation agent, and it is obtained via hydrolytic condensation of 3-aminopropyltriethoxysilane (APTES). During the functionalization process, the amino groups on OA-POSS combine with carboxylic groups on the bare CDs via formation of amide bond to construct organic-inorganic hybrid carbon dots. The obtained CDs/POSS are well dispersed in aqueous medium with a diameter of ca. 3.6 nm. It is demonstrated that CDs/POSS provide favorable photoluminescent property with a quantum yield of 24.0%. They also exhibit resistance to photobleaching and excellent photoluminescence stability in the presence of biological sample matrix (characterized by heavy metals and organic molecules), which facilitate cell imaging in biological systems. Both the photoluminescent emission wavelength and the fluorescence intensity depend closely on the excitation wavelength, and thus, it provides a potential for multicolor imaging as demonstrated with HeLa cells and MCF-7 cells.

  3. Accurate length control of supramolecular oligomerization: Vernier assemblies.

    Science.gov (United States)

    Hunter, Christopher A; Tomas, Salvador

    2006-07-12

    Linear oligomeric supramolecular assemblies of defined length have been generated using the Vernier principle. Two molecules, containing a different number (n and m) of mutually complementary binding sites, separated by the same distance, interact with each other to form an assembly of length (n x m). The assembly grows in the same way as simple supramolecular polymers, but at a molecular stop signal, when the binding sites come into register, the assembly terminates giving an oligomer of defined length. This strategy has been realized using tin and zinc porphyrin oligomers as the molecular building blocks. In the presence of isonicotinic acid, a zinc porphyrin trimer and a tin porphyrin dimer form a 3:4 triple stranded Vernier assembly six porphyrins long. The triple strand Vernier architecture introduced here adds an additional level of cooperativity, yielding a stability and selectivity that cannot be achieved via a simple Vernier approach. The assembly properties of the system were characterized using fluorescence titrations and size-exclusion chromatography (SEC). Assembly of the Vernier complex is efficient at micromolar concentrations in nonpolar solvents, and under more competitive conditions, a variety of fragmentation assemblies can be detected, allowing determination of the stability constants for this system and detailed speciation profiles to be constructed.

  4. Oligomerization of optically active N-(4-hydroxyphenylmandelamide in the presence of β-cyclodextrin and the minor role of chirality

    Directory of Open Access Journals (Sweden)

    Helmut Ritter

    2014-10-01

    Full Text Available The oxidative oligomerization of a chiral mandelamide derivative (N-(4-hydroxyphenylmandelamide, 1 was performed in the presence of horseradish peroxidase, laccase and N,N'-bis(salicylideneethylenediamine-iron(II to obtain chiral oligophenols 2. The low enantioselectivity of the enzymatic catalyzed asymmetric enantiomer-differentiating oligomerizations was investigated. In addition, the poor influence of cyclodextrin on the enantioselectivity of enzymatic catalyzed asymmetric enantiomer-differentiating oligomerizations was studied.

  5. Children's Empowerment in Play

    Science.gov (United States)

    Canning, Natalie

    2007-01-01

    This article examines the level of empowerment and autonomy children can create in their play experiences. It examines the play discourses that children build and maintain and considers the importance of play contexts in supporting children's emotional and social development. These aspects of play are often unseen or misunderstood by the adult…

  6. The Play of Psychotherapy

    Science.gov (United States)

    Marks-Tarlow, Terry

    2012-01-01

    The author reviews the role of play within psychotherapy. She does not discuss the formal play therapy especially popular for young children, nor play from the Jungian perspective that encourages the use of the sand tray with adults. Instead, she focuses on the informal use of play during psychotherapy as it is orchestrated intuitively. Because…

  7. Two people playing together: some thoughts on play, playing, and playfulness in psychoanalytic work.

    Science.gov (United States)

    Vliegen, Nicole

    2009-01-01

    Children's play and the playfulness of adolescents and adults are important indicators of personal growth and development. When a child is not able to play, or an adolescent/adult is not able to be playful with thoughts and ideas, psychotherapy can help to find a more playful and creative stance. Elaborating Winnicott's (1968, p. 591) statement that "psychotherapy has to do with two people playing together," three perspectives on play in psychotherapy are discussed. In the first point of view, the child gets in touch with and can work through aspects of his or her inner world, while playing in the presence of the therapist. The power of play is then rooted in the playful communication with the self In a second perspective, in play the child is communicating aspects of his or her inner world to the therapist as a significant other. In a third view, in "playing together" child and therapist are coconstructing new meanings. These three perspectives on play are valid at different moments of a therapy process or for different children, depending on the complex vicissitudes of the child's constitution, life experiences, development, and psychic structure. Concerning these three perspectives, a parallel can be drawn between the therapist's attitude toward the child's play and the way the therapist responds to the verbal play of an adolescent or adult. We illustrate this with the case of Jacob, a late adolescent hardly able to play with ideas.

  8. Applying Play to Therapy.

    Science.gov (United States)

    Ritter, Patricia S.; Fokes, Joann

    The objectives of this paper are (1) to present the relationship of play to language and cognition, (2) to describe the stages of play and discuss recent literature about the characteristics of play, and (3) to describe the use of play with the multifaceted goals of cognition, pragmatics, semantics, syntax, and morphology as an intervention…

  9. Characterization of tau oligomeric seeds in progressive supranuclear palsy.

    Science.gov (United States)

    Gerson, Julia E; Sengupta, Urmi; Lasagna-Reeves, Cristian A; Guerrero-Muñoz, Marcos J; Troncoso, Juan; Kayed, Rakez

    2014-06-14

    Progressive supranuclear palsy (PSP) is a neurodegenerative tauopathy which is primarily defined by the deposition of tau into globose-type neurofibrillary tangles (NFT). Tau in its native form has important functions for microtubule dynamics. Tau undergoes alternative splicing in exons 2, 3, and 10 which results in six different isoforms. Products of splicing on exon 10 are the most prone to mutations. Three repeat (3R) and four repeat (4R) tau, like other disease-associated amyloids, can form oligomers which may then go on to further aggregate and form fibrils. Recent studies from our laboratory and others have provided evidence that tau oligomers, not NFTs, are the most toxic species in neurodegenerative tauopathies and seed the pathological spread of tau. Analysis of PSP brain sections revealed globose-type NFTs, as well as both phosphorylated and unphosphorylated tau oligomers. Analysis of PSP brains via Western blot and ELISA revealed the presence of increased levels of tau oligomers compared to age-matched control brains. Oligomers were immunoprecipitated from PSP brain and were capable of seeding the oligomerization of both 3R and 4R tau isoforms. This is the first time tau oligomers have been characterized in PSP. These results indicate that tau oligomers are an important component of PSP pathology, along with NFTs. The ability of PSP brain-derived tau oligomers to seed 3R and 4R tau suggests that these oligomers represent the pathological species responsible for disease propagation and the presence of oligomers in a pure neurodegenerative tauopathy implies a common neuropathological process for tau seen in diseases with other amyloid proteins.

  10. Interfacial behavior of cytoplasmic and mitochondrial creatine kinase oligomeric states.

    Science.gov (United States)

    Vernoux, Nathalie; Granjon, Thierry; Marcillat, Olivier; Besson, Françoise; Vial, Christian

    2006-03-01

    Adsorption to the air/water interface of isoenzymes of creatine kinase was investigated using surface pressure-area isotherms and Brewster angle microscopy (BAM) observations. Octameric mitochondrial creatine kinase (mtCK) exhibits a significant affinity for the air/water interface. Whatever the mode of formation of the interfacial film, i.e., injection of the protein in the subphase or spreading onto the buffer surface, the final arrangement and conformation adopted by mtCK molecules lead to a similar result. In contrast, the dimeric isoenzymes mtCK and cytosolic MMCK do not induce any surface pressure variation. However, when the subphase contains 0.3M NaCl, both isoenzymes adsorb to the interface. When treated with 0.8 or 3M GdnHCl, muscle creatine kinase (MMCK) becomes surface active and occupies a greater surface than mtCK. This result contrasts with previous observations, often derived from monomeric proteins, that their surface activity is increased upon unfolding. It underlines the possible influence exerted by the protein oligomeric state on its interfacial activity. At a subphase pH of 8.8, which corresponds to the pI of octameric mtCK, the profiles of the isotherms obtained with dimeric and octameric states and the resistance to compression of the protein monolayers are significantly affected when compared to those recorded at pH 7.4. These data suggest that the octamer is more hydrophobic than the dimer and may contribute to explaining why octamers bind to the inner mitochondrial membrane while dimers do not. Copyright 2005 Wiley Periodicals, Inc.

  11. Phosphate and HEPES buffers potently affect the fibrillation and oligomerization mechanism of Alzheimer's A{beta} peptide

    Energy Technology Data Exchange (ETDEWEB)

    Garvey, Megan; Tepper, Katharina [Max-Planck-Forschungsstelle fuer Enzymologie der Proteinfaltung, Weinbergweg 22, D-06120 Halle (Saale) (Germany); Haupt, Caroline [Institute fuer Physik, Biophysik, Martin-Luther Universitaet Halle-Wittenberg, Betty-Heimann-Str. 7, D-06120 Halle (Saale) (Germany); Knuepfer, Uwe [Leibniz-Institute for Infection Biology and Natural Product Research, Beutenbergstr. 11a, D-07745 Jena (Germany); Klement, Karolin; Meinhardt, Jessica [Leibniz-Institute for Age Research (FLI), Beutenbergstr. 11, D-07745 Jena (Germany); Horn, Uwe [Leibniz-Institute for Infection Biology and Natural Product Research, Beutenbergstr. 11a, D-07745 Jena (Germany); Balbach, Jochen [Institute fuer Physik, Biophysik, Martin-Luther Universitaet Halle-Wittenberg, Betty-Heimann-Str. 7, D-06120 Halle (Saale) (Germany); Faendrich, Marcus, E-mail: fandrich@enzyme-halle.mpg.de [Max-Planck-Forschungsstelle fuer Enzymologie der Proteinfaltung, Weinbergweg 22, D-06120 Halle (Saale) (Germany); Bio zentrum, Martin-Luther Universitaet Halle-Wittenberg, Weinbergweg 22, D-06120 Halle (Saale) (Germany)

    2011-06-10

    Highlights: {yields} Sodium phosphate buffer accelerated A{beta}(1-40) nucleation relative to HEPES. {yields} A{beta}(1-40) fibrils formed in the two buffers show only minor structural differences. {yields} NMR revealed that A{beta}(1-40) histidine residues mediate buffer dependent changes. -- Abstract: The oligomerization of A{beta} peptide into amyloid fibrils is a hallmark of Alzheimer's disease. Due to its biological relevance, phosphate is the most commonly used buffer system for studying the formation of A{beta} and other amyloid fibrils. Investigation into the characteristics and formation of amyloid fibrils frequently relies upon material formed in vitro, predominantly in phosphate buffers. Herein, we examine the effects on the fibrillation and oligomerization mechanism of A{beta} peptide that occur due solely to the influence of phosphate buffer. We reveal that significant differences in amyloid fibrillation are observed due to fibrillation being initiated in phosphate or HEPES buffer (at physiological pH and temperature). Except for the differing buffer ions, all experimental parameters were kept constant. Fibril formation was assessed using fluorescently monitored kinetic studies, microscopy, X-ray fiber diffraction and infrared and nuclear magnetic resonance spectroscopies. Based on this set up, we herein reveal profound effects on the mechanism and speed of A{beta} fibrillation. The three histidine residues at positions 6, 13 and 14 of A{beta}(1-40) are instrumental in these mechanistic changes. We conclude that buffer plays a more significant role in fibril formation than has been generally acknowledged.

  12. Bax phosphorylation association with nucleus and oligomerization after neonatal hypoxia-ischemia.

    Science.gov (United States)

    Infante, Smitha Krishna; Oberhauser, Andres F; Perez-Polo, J Regino

    2013-09-01

    Neonatal hypoxia-ischemia (HI) is a common occurrence in preterm and low-birth-weight infants, and the incidence of low-birth-weight and preterm births is increasing. Characterization of brain injury after HI is of critical importance in developing new treatments that more accurately target the injury. After severe HI, neuronal cells undergo necrosis and secondary apoptosis of the surrounding cells as a result of neuroinflammation. We sought to characterize the biochemical pathways associated with cell death after HI. Bax, a cell death signaling protein, is activated after HI and translocates to the nucleus, endoplasmic reticulum, and mitochondria. The translocation patterns of Bax affect the resultant cell death phenotype (necrotic or apoptotic) observed. Although Bax is known to oligomerize once it is activated, less is known about the factors that control its translocation and oligomerization. We hypothesize that Bax kinase-specific phosphorylation determines its oligomerization and intracellular localization. Using well-established in vivo and in vitro models of neonatal HI, we characterized Bax oligomerization and multiorganelle translocation. We found that HI-dependent phosphorylation of Bax determines its oligomerization status and multiorganelle localization, and, ultimately, the cell death phenotype observed. Understanding the mechanisms of Bax translocation will aid in the rational design of therapeutic strategies that decrease the trauma resulting from HI-associated inflammation.

  13. Tris-acetate polyacrylamide gradient gel electrophoresis for the analysis of protein oligomerization.

    Science.gov (United States)

    Cubillos-Rojas, Monica; Schneider, Taiane; Sánchez-Tena, Susana; Bartrons, Ramon; Ventura, Francesc; Rosa, Jose Luis

    2016-02-01

    Here we report a new approach for studying protein oligomerization in cells using a single electrophoresis gel. We combined the use of a crosslinking reagent for sample preparation, such as glutaraldehyde, with the analysis of oligomers by Tris-acetate polyacrylamide gel electrophoresis. The use of a 3-15% Tris-acetate polyacrylamide gradient gel allows for the simultaneous analysis of proteins of masses ranging from 10 to 500 kDa. We showed the usefulness of this method for analyzing endogenous p53 oligomerization with high resolution and sensitivity in human cells. Oligomerization analysis was dependent on the crosslinker concentration used. We also showed that this method could be used to study the regulation of oligomerization. In all experiments, Tris-acetate polyacrylamide gel electrophoresis proved to be a robust, manageable, and cost- and time-efficient method that provided excellent results using a single gel. This approach can be easily extrapolated to the study of other oligomers. All of these features make this method a highly useful tool for the analysis of protein oligomerization.

  14. A fluorimetric readout reporting the kinetics of nucleotide-induced human ribonucleotide reductase oligomerization.

    Science.gov (United States)

    Fu, Yuan; Lin, Hong-Yu; Wisitpitthaya, Somsinee; Blessing, William A; Aye, Yimon

    2014-11-24

    Human ribonucleotide reductase (hRNR) is a target of nucleotide chemotherapeutics in clinical use. The nucleotide-induced oligomeric regulation of hRNR subunit α is increasingly being recognized as an innate and drug-relevant mechanism for enzyme activity modulation. In the presence of negative feedback inhibitor dATP and leukemia drug clofarabine nucleotides, hRNR-α assembles into catalytically inert hexameric complexes, whereas nucleotide effectors that govern substrate specificity typically trigger α-dimerization. Currently, both knowledge of and tools to interrogate the oligomeric assembly pathway of RNR in any species in real time are lacking. We therefore developed a fluorimetric assay that reliably reports on oligomeric state changes of α with high sensitivity. The oligomerization-directed fluorescence quenching of hRNR-α, covalently labeled with two fluorophores, allows for direct readout of hRNR dimeric and hexameric states. We applied the newly developed platform to reveal the timescales of α self-assembly, driven by the feedback regulator dATP. This information is currently unavailable, despite the pharmaceutical relevance of hRNR oligomeric regulation.

  15. Biocatalytically Oligomerized Epicatechin with Potent and Specific Anti-proliferative Activity for Human Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Ramaswamy Nagarajan

    2008-11-01

    Full Text Available Catechins, naturally occurring flavonoids derived from wine and green tea, are known to exhibit multiple health benefits. Epigallocatechin gallate (EGCG is one of the most widely investigated catechins, but its efficacy in cancer therapy is still inconsistent and limited. The poor stability of EGCG has contributed to the disparity in the reported anti-cancer activity and other beneficial properties. Here we report an innovative enzymatic strategy for the oligomerization of catechins (specifically epicatechin that yields stable, water-soluble oligomerized epicatechins with enhanced and highly specific anti-proliferative activity for human breast cancer cells. This one-pot oxidative oligomerization is carried out in ambient conditions using Horseradish Peroxidase (HRP as a catalyst yielding water-soluble oligo(epicatechins. The oligomerized epicatechins obtained exhibit excellent growth inhibitory effects against human breast cancer cells with greater specificity towards growth-inhibiting cancer cells as opposed to normal cells, achieving a high therapeutic differential. Our studies indicate that water-soluble oligomeric epicatechins surpass EGCG in stability, selectivity and efficacy at lower doses.

  16. The play grid

    DEFF Research Database (Denmark)

    Fogh, Rune; Johansen, Asger

    2013-01-01

    In this paper we propose The Play Grid, a model for systemizing different play types. The approach is psychological by nature and the actual Play Grid is based, therefore, on two pairs of fundamental and widely acknowledged distinguishing characteristics of the ego, namely: extraversion vs...... at the Play Grid. Thus, the model has four quadrants, each of them describing one of four play types: the Assembler, the Director, the Explorer, and the Improviser. It is our hope that the Play Grid can be a useful design tool for making entertainment products for children....

  17. Role-Playing Mitosis.

    Science.gov (United States)

    Wyn, Mark A.; Stegink, Steven J.

    2000-01-01

    Introduces a role playing activity that actively engages students in the learning process of mitosis. Students play either chromosomes carrying information, or cells in the cell membrane. (Contains 11 references.) (Author/YDS)

  18. Play the Tuberculosis Game

    Science.gov (United States)

    ... Questionnaire Tuberculosis Play Tuberculosis Experiments & Discoveries About the game Discover and experience some of the classic methods ... last will in Paris. Play the Blood Typing Game Try to save some patients and learn about ...

  19. Play the MRI Game

    Science.gov (United States)

    ... Teachers' Questionnaire MRI Play MRI the Magnetic Miracle Game About the game In the MRI imaging technique, strong magnets and ... last will in Paris. Play the Blood Typing Game Try to save some patients and learn about ...

  20. Play the Electrocardiogram Game

    Science.gov (United States)

    ... and Work Teachers' Questionnaire Electrocardiogram Play the ECG Game About the game ECG is used for diagnosing heart conditions by ... last will in Paris. Play the Blood Typing Game Try to save some patients and learn about ...

  1. Learning Through Play

    Science.gov (United States)

    ... play, such as using play dough, LEGOs, and board games. Toys such as puzzles, pegboards, beads, and lacing ... Building sets, books, bicycles, roller skates, ice skates, board games, checkers, beginning sports • Middle Schoolers and Adolescents: Athletics, ...

  2. Children, Time, and Play

    DEFF Research Database (Denmark)

    Elkind, David; Rinaldi, Carla; Flemmert Jensen, Anne;

    Proceedings from the conference "Children, Time, and Play". Danish University of Education, January 30th 2003.......Proceedings from the conference "Children, Time, and Play". Danish University of Education, January 30th 2003....

  3. Role-Playing Mitosis.

    Science.gov (United States)

    Wyn, Mark A.; Stegink, Steven J.

    2000-01-01

    Introduces a role playing activity that actively engages students in the learning process of mitosis. Students play either chromosomes carrying information, or cells in the cell membrane. (Contains 11 references.) (Author/YDS)

  4. Play at Work

    DEFF Research Database (Denmark)

    Meier Sørensen, Bent; Spoelstra, Sverre

    2012-01-01

    for business and the other insists that work and play are largely indistinguishable in the postindustrial organization. Our field study of a design and communications company in Denmark shows that organizational play can be much more than just functional to the organization. We identify three ways in which......The interest in organizational play is growing, both in popular business discourse and organization studies. As the presumption that play is dysfunctional for organizations is increasingly discarded, the existing positions may be divided into two camps; one proposes ‘serious play’ as an engine...... workplaces engage in play: play as a (serious) continuation of work, play as a (critical) intervention into work and play as an (uninvited) usurpation of work....

  5. Playing with social identities

    DEFF Research Database (Denmark)

    Winther-Lindqvist, Ditte Alexandra

    2013-01-01

    This chapter offers support for Vygotsky’s claim that all play involves both an imagined situation as well as rules. Synthesising Schousboe’s comprehensive model of spheres of realities in playing (see Chapter 1, this volume) with Lev Vygotskys insight that all playing involve rules as well...

  6. Toddlers: Learning by Playing

    Science.gov (United States)

    ... Feeding Your 1- to 2-Year-Old Toddlers: Learning by Playing KidsHealth > For Parents > Toddlers: Learning by Playing Print A A A What's in ... child's play, but toddlers are hard at work learning important physical skills as they gain muscle control, ...

  7. Playing against the Game

    Science.gov (United States)

    Remmele, Bernd

    2017-01-01

    The paper first outlines a differentiation of play/game-motivations that include "negative" attitudes against the play/game itself like cheating or spoilsporting. This problem is of particular importance in concern of learning games because they are not "played" for themselves--at least in the first place--but due to an…

  8. Play the Mosquito Game

    Science.gov (United States)

    ... and Work Teachers' Questionnaire Malaria Play the Mosquito Game Play the Parasite Game About the games Malaria is one of the world's most common ... last will in Paris. Play the Blood Typing Game Try to save some patients and learn about ...

  9. (Steering) interactive play behavior

    NARCIS (Netherlands)

    Delden, van Robertus Wilhelmus

    2017-01-01

    Play is a powerful means to have an impact on the cognitive, social-emotional, and/or motor skills development. The introduction of technology brings new possibilities to provide engaging and entertaining whole-body play activities. Technology mediates the play activities and in this way changes how

  10. (Steering) interactive play behavior

    NARCIS (Netherlands)

    van Delden, Robertus Wilhelmus

    2017-01-01

    Play is a powerful means to have an impact on the cognitive, social-emotional, and/or motor skills development. The introduction of technology brings new possibilities to provide engaging and entertaining whole-body play activities. Technology mediates the play activities and in this way changes how

  11. Interleukin-1 beta converting enzyme requires oligomerization for activity of processed forms in vivo.

    Science.gov (United States)

    Gu, Y; Wu, J; Faucheu, C; Lalanne, J L; Diu, A; Livingston, D J; Su, M S

    1995-05-01

    Interleukin-1 beta converting enzyme (ICE) is composed of 10' (p10) and 20 kDa (p20) subunits, which are derived from a common 45 kDa precursor. Recent crystallographic studies have shown that ICE exists as a tetramer (p20/p10)2 in the crystal lattice. We provide evidence that the p10 and p20 subunits of ICE associate as oligomers in transfected COS cells. Using intragenic complementation, we show that the activity of a p10/p10 interface mutant defective in autoprocessing can be restored by co-expression with active site ICE mutants. Different active site mutants can also complement each other by oligomerization to form active ICE. These studies indicate that ICE precursor polypeptides may associate in different quaternary structures and that oligomerization is required for autoprocessing. Furthermore, integenic complementation of active site mutants of ICE and an ICE homolog restores autoprocessing activity, suggesting that hetero-oligomerization occurs between ICE homologs.

  12. Reactive bay functionalized perylene monoimide-polyhedral oligomeric silsesquioxane organic electronic dye

    Directory of Open Access Journals (Sweden)

    Wangatia Lodrick Makokha

    2015-03-01

    Full Text Available Aggregation-induced quenching is particularly detrimental in perylene diimides, which are characterized by a near-unity fluorescence quantum yield in solution but are far less emissive in the solid state. Previously, perylene diimide has been improved by linking it to the inorganic cage of polyhedral oligomeric silsesquioxanes. As a further study on perylene diimidepolyhedral oligomeric silsesquioxanes, we report on a double functionalized molecular structure, which can be used for substitution at the bay area and as a side group in other materials. Typical solution absorption and emission features of the perylene diimide fragment have been observed in this new reactive perylene diimide-polyhedral oligomeric silsesquioxane. Moreover, reduced stacking during aggregation and spherical particles exhibiting solid fluorescence have been obtained. Organic semiconducting material with enhanced solid state photophysical properties, like solid fluorescence is a subject of great interest owing to its possible high-tech applications in optoelectronic devices.

  13. p53 oligomerization status modulates cell fate decisions between growth, arrest and apoptosis.

    Science.gov (United States)

    Fischer, Nicholas W; Prodeus, Aaron; Malkin, David; Gariépy, Jean

    2016-12-01

    Mutations in the oligomerization domain of p53 are genetically linked to cancer susceptibility in Li-Fraumeni Syndrome. These mutations typically alter the oligomeric state of p53 and impair its transcriptional activity. Activation of p53 through tetramerization is required for its tumor suppressive function by inducing transcriptional programs that lead to cell fate decisions such as cell cycle arrest or apoptosis. How p53 chooses between these cell fate outcomes remains unclear. Here, we use 5 oligomeric variants of p53, including 2 novel p53 constructs, that yield either monomeric, dimeric or tetrameric forms of p53 and demonstrate that they induce distinct cellular activities and gene expression profiles that lead to different cell fate outcomes. We report that dimeric p53 variants are cytostatic and can arrest cell growth, but lack the ability to trigger apoptosis in p53-null cells. In contrast, p53 tetramers induce rapid apoptosis and cell growth arrest, while a monomeric variant is functionally inactive, supporting cell growth. In particular, the expression of pro-arrest CDKN1A and pro-apoptotic P53AIP1 genes are important cell fate determinants that are differentially regulated by the oligomeric state of p53. This study suggests that the most abundant oligomeric species of p53 present in resting cells, namely p53 dimers, neither promote cell growth or cell death and that shifting the oligomeric state equilibrium of p53 in cells toward monomers or tetramers is a key parameter in p53-based cell fate decisions.

  14. A stable transcription factor complex nucleated by oligomeric AML1–ETO controls leukaemogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiao-Jian; Wang, Zhanxin; Wang, Lan; Jiang, Yanwen; Kost, Nils; Soong, T. David; Chen, Wei-Yi; Tang, Zhanyun; Nakadai, Tomoyoshi; Elemento, Olivier; Fischle, Wolfgang; Melnick, Ari; Patel, Dinshaw J.; Nimer, Stephen D.; Roeder, Robert G.

    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 multivalent 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.

  15. Requirements and ontology for a G protein-coupled receptor oligomerization knowledge base

    Directory of Open Access Journals (Sweden)

    Parmentier Marc

    2007-05-01

    Full Text Available Abstract Background G Protein-Coupled Receptors (GPCRs are a large and diverse family of membrane proteins whose members participate in the regulation of most cellular and physiological processes and therefore represent key pharmacological targets. Although several bioinformatics resources support research on GPCRs, most of these have been designed based on the traditional assumption that monomeric GPCRs constitute the functional receptor unit. The increase in the frequency and number of reports about GPCR dimerization/oligomerization and the implication of oligomerization in receptor function makes necessary the ability to store and access information about GPCR dimers/oligomers electronically. Results We present here the requirements and ontology (the information scheme to describe oligomers and associated concepts and their relationships for an information system that can manage the elements of information needed to describe comprehensively the phenomena of both homo- and hetero-oligomerization of GPCRs. The comprehensive information management scheme that we plan to use for the development of an intuitive and user-friendly GPCR-Oligomerization Knowledge Base (GPCR-OKB is the result of a community dialog involving experimental and computational colleagues working on GPCRs. Conclusion Our long term goal is to disseminate to the scientific community organized, curated, and detailed information about GPCR dimerization/oligomerization and its related structural context. This information will be reported as close to the data as possible so the user can make his own judgment on the conclusions drawn for a particular study. The requirements and ontology described here will facilitate the development of future information systems for GPCR oligomers that contain both computational and experimental information about GPCR oligomerization. This information is freely accessible at http://www.gpcr-okb.org.

  16. Playing with social identities

    DEFF Research Database (Denmark)

    Winther-Lindqvist, Ditte Alexandra

    2013-01-01

    This chapter offers support for Vygotsky’s claim that all play involves both an imagined situation as well as rules. Synthesising Schousboe’s comprehensive model of spheres of realities in playing (see Chapter 1, this volume) with Lev Vygotskys insight that all playing involve rules as well...... as pretence, children’s play is understood as an activity involving rules of the social order (roles and positions) as well as identification processes (imagined situations). The theoretical argumentation builds on empirical examples obtained in two different Danish day-care centres. The chapter is informed...... by ethnographic observations and draws on illustrative examples with symbolic group play as well as game-play with rules (soccer) among 5 year old boys. Findings suggest that day-care children’s play, involves negotiation of roles, positioning and identification, and rules – and that these negotiations...

  17. Hydrogen ions directly regulating the oligomerization state of Photosystem I in intact Spirulina platensis cells

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    H+ concentration induced-monomerization or trimerization of photosystem I (PSI) in cyanobacteria has never been directly observed. In this work, taking characteristic spectra for the trimers and monomers as the indicators, it was experimentally demonstrated that H+ could induce the oligomeric changes of PSI reaction centers in the intact Spirulina ,platensis cells and also in the isolated thylakoid membrane complexes. Especially, the higher concentration of H+ would induce the monomerization while the lower the trimerization, suggesting the electrostatic interaction should be mainly responsible forchanges in the oligomeric state of PSI in Spirulina platensis.

  18. Tip-induced C-H activation and oligomerization of thienoanthracenes.

    Science.gov (United States)

    Dinca, L E; MacLeod, J M; Lipton-Duffin, J; Fu, C; Ma, D; Perepichka, D F; Rosei, F

    2014-08-14

    The tip of a scanning tunneling microscope (STM) can be used to dehydrogenate freely-diffusing tetrathienoanthracene (TTA) molecules on Cu(111), trapping the molecules into metal-coordinated oligomeric structures. The process proceeds at bias voltages above ~3 V and produces organometallic structures identical to those resulting from the thermally-activated cross-coupling of a halogenated analogue. The process appears to be substrate dependent: no oligomerization was observed on Ag(111) or HOPG. This approach demonstrates the possibility of controlled synthesis and nanoscale patterning of 2D oligomer structures on selected surfaces.

  19. Late Modern Play Culture

    DEFF Research Database (Denmark)

    Skovbjerg-Karoff, Helle

    2008-01-01

    Children's play and culture have changed over the recent years, and it is possible to understand the changes as a result of a more general change in society. We witness a large degree of changes connected to demographical aspects of children's lives. First of all it is a fact that large groups....... They are changing play arenas in order to find the identity, which suits them. In order to play children must know and be conscious of the cultural heritage, which contains knowledge of the way to organize in the playing session, the aesthetics, the techniques of playing, and this is something that is handed down...... from one generation to the next. Because older children are no longer present as younger children grow up, the traditional "cultural leaders" are gone. They have taken with them much of the inspiration for play as well as important knowledge about how to organise a game. In that sense we can say...

  20. Play, dreams, and creativity.

    Science.gov (United States)

    Oremland, J D

    1998-01-01

    Viewed ontogenetically, creating, dreaming, and playing are a variant of object relatedness. It is suggested that in recapitulating the ontogenetic sequence, creating, dreaming, and playing each as a process initiates by de-differentiation to primal union, evolves into transitional functioning, and consummates in tertiary cognitive discourse. The products of the triad--the created object, the dream, and play--are viewed as synergistic psychodynamic composites of topical, personal, and arche-typical imperatives. Creating, dreaming, and playing are easily overburdened by events, becoming stereotypical and repetitious. Nowhere is this more clearly seen than in the play of chronically ill, hospitalized children. It is suggested that with development generally, playing is replaced by formalized games; only dreaming continues as the vestige of early creative abilities.

  1. Play and virtuality

    Directory of Open Access Journals (Sweden)

    Svein Sando

    2010-07-01

    Full Text Available The similarities between virtuality and play are obvious, beginning with, for instance, the ubiquitous character of both. This paper deals with how insights from research on play can be used to enlighten our understanding of the ethical dimensions of activities in cyberspace, and vice versa. In particular, a central claim that play is beyond vice and virtue is debated and contested.http://dx.doi.org/10.5324/eip.v4i2.1762

  2. Why do Dolphins Play?

    Directory of Open Access Journals (Sweden)

    Stan A. Kuczaj

    2014-05-01

    Full Text Available Play is an important aspect of dolphin life, perhaps even an essential one. Play provides opportunities for dolphin calves to practice and perfect locomotor skills, including those involved in foraging and mating strategies and behaviors. Play also allows dolphin calves to learn important social skills and acquire information about the characteristics and predispositions of members of their social group, particularly their peers. In addition to helping dolphin calves learn how to behave, play also provides valuable opportunities for them to learn how to think. The ability to create and control play contexts enables dolphins to create novel experiences for themselves and their playmates under relatively safe conditions. The behavioral variability and individual creativity that characterize dolphin play yield ample opportunities for individual cognitive development as well as social learning, and sometimes result in innovations that are reproduced by other members of the group. Although adults sometimes produce innovative play, calves are the primary source of such innovations. Calves are also more likely to imitate novel play behaviors than are adults, and so calves contribute significantly to both the creation and transmission of novel play behaviors within a group. Not unexpectedly, then, the complexity of dolphin play increases with the involvement of peers. As a result, the opportunity to observe and/or interact with other dolphin calves enhances the effects of play on the acquisition and maintenance of flexible problem solving skills, the emergence and strengthening of social and communicative competencies, and the establishment of social relationships. It seems that play may have evolved to help young dolphins learn to adapt to novel situations in both their physical and social worlds, the beneficial result being a set of abilities that increases the likelihood that an individual survives and reproduces.

  3. PlayBook三人行

    Institute of Scientific and Technical Information of China (English)

    黑莓时光

    2011-01-01

    PlayBook,来自非苹果的另外一个水果——黑莓,它不是iPad,却也是平板。PBer,这个并不完美的平板——PlayBook的用户,他们开朗、认真、执着。热爱PlayBook的三人,拥有各自的人生轨迹,却挂着同样的嘴角上扬。

  4. Play your part

    CERN Document Server

    Ramsey, Gaynor

    1978-01-01

    Play your part is a collection of then situations in which students have to take on the roles of particular people and express their opinions, feelings or arguments about the situation. Play your part is intended for use with advanced students of English.

  5. Role Playing and Skits

    Science.gov (United States)

    Letwin, Robert, Ed.

    1975-01-01

    Explores non-scripted role playing, dialogue role playing, sociodrama, and skits as variations of simulation techniques. Provides step-by-step guidelines for conducting such sessions. Successful Meetings, Bill Communications, Inc., 1422 Chestnut Street, Philadelphia, Pa. 19102. Subscription Rates: yearly (US, Canada, Mexico) $14.00; elsewhere,…

  6. The Play's the Thing

    Science.gov (United States)

    Bateman, Barbara

    2005-01-01

    The modern special education theater in the United States has hosted many plays, none with a larger or more diverse cast than the learning disabilities (LD) play. During the prologue, the children with LD were waiting in the wings, not yet identified as LD but there, nonetheless. With the advent of compulsory education in this country, awareness…

  7. Playfulness and Openness

    DEFF Research Database (Denmark)

    Marchetti, Emanuela; Petersson, Eva

    2011-01-01

    What does it mean to design a playful learning tool? What is needed for a learning tool to be perceived by potential users as playful? These questions emerged reflecting on a Participatory Design process aimed at enhancing museum-learning practice from the perspective of primary school children. ...

  8. Play as Experience

    Science.gov (United States)

    Henricks, Thomas S.

    2015-01-01

    The author investigates what he believes one of the more important aspects of play--the experience it generates in its participants. He considers the quality of this experience in relation to five ways of viewing play--as action, interaction, activity, disposition, and within a context. He treats broadly the different forms of affect, including…

  9. Art of Play

    DEFF Research Database (Denmark)

    Froes, Isabel Cristina G.; Walker, Kevin

    2011-01-01

    Play is a key element in cultural development, according to the Dutch historian Johan Huizinga. Nowadays many of us interact with other people in online games and social networks, through multiple digital devices. But harnessing playful activities for museum learning is mostly undeveloped. In thi...

  10. Family Play Therapy.

    Science.gov (United States)

    Ariel, Shlomo

    This paper examines a case study of family play therapy in Israel. The unique contributions of play therapy are evaluated including the therapy's accessibility to young children, its richness and flexibility, its exposure of covert patterns, its wealth of therapeutic means, and its therapeutic economy. The systematization of the therapy attempts…

  11. Return to Play

    Science.gov (United States)

    Mangan, Marianne

    2013-01-01

    Call it physical activity, call it games, or call it play. Whatever its name, it's a place we all need to return to. In the physical education, recreation, and dance professions, we need to redesign programs to address the need for and want of play that is inherent in all of us.

  12. Playful Collaboration (Or Not)

    DEFF Research Database (Denmark)

    Bogers, Marcel; Sproedt, Henrik

    2012-01-01

    This article explores how playing games can be used to teach intangible social interaction across boundaries, in particular within open collaborative innovation. We present an exploratory case study of how students learned from playing a board game in a graduate course of the international...... imply several opportunities and challenges within education and beyond....

  13. Art of Play

    DEFF Research Database (Denmark)

    Froes, Isabel Cristina G.; Walker, Kevin

    2011-01-01

    Play is a key element in cultural development, according to the Dutch historian Johan Huizinga. Nowadays many of us interact with other people in online games and social networks, through multiple digital devices. But harnessing playful activities for museum learning is mostly undeveloped. In thi...

  14. Play framework cookbook

    CERN Document Server

    Reelsen, Alexander

    2015-01-01

    This book is aimed at advanced developers who are looking to harness the power of Play 2.x. This book will also be useful for professionals looking to dive deeper into web development. Play 2 .x is an excellent framework to accelerate your learning of advanced topics.

  15. Let's Just Play

    Science.gov (United States)

    Schmidt, Janet

    2003-01-01

    Children have a right to play. The idea is so simple it seems self-evident. But a stroll through any toy superstore, or any half-hour of so-called "children's" programming on commercial TV, makes it clear that violence, not play, dominates what's being sold. In this article, the author discusses how teachers and parents share the responsibility in…

  16. Styrene oligomerization as a molecular probe reaction for Brønsted acidity at the nanoscale

    NARCIS (Netherlands)

    Aramburo Corrales, Luis; Wirick, Sue; Miedema, P.S.; Buurmans, I.L.C.; de Groot, F.M.F.; Weckhuysen, B.M.

    2012-01-01

    The Brønsted acid-catalyzed oligomerization of 4-fluorostyrene has been studied on a series ofH-ZSM-5 zeolite powders, steamed under different conditions, with a combination of UV-Vismicro-spectroscopy and Scanning Transmission X-ray Microscopy (STXM). UV-Vis microspectroscopyand STXM have been used

  17. Selective Antimicrobial Activities and Action Mechanism of Micelles Self-Assembled by Cationic Oligomeric Surfactants.

    Science.gov (United States)

    Zhou, Chengcheng; Wang, Fengyan; Chen, Hui; Li, Meng; Qiao, Fulin; Liu, Zhang; Hou, Yanbo; Wu, Chunxian; Fan, Yaxun; Liu, Libing; Wang, Shu; Wang, Yilin

    2016-02-17

    This work reports that cationic micelles formed by cationic trimeric, tetrameric, and hexameric surfactants bearing amide moieties in spacers can efficiently kill Gram-negative E. coli with a very low minimum inhibitory concentration (1.70-0.93 μM), and do not cause obvious toxicity to mammalian cells at the concentrations used. With the increase of the oligomerization degree, the antibacterial activity of the oligomeric surfactants increases, i.e., hexameric surfactant > tetrameric surfactant > trimeric surfactant. Isothermal titration microcalorimetry, scanning electron microscopy, and zeta potential results reveal that the cationic micelles interact with the cell membrane of E. coli through two processes. First, the integrity of outer membrane of E. coli is disrupted by the electrostatic interaction of the cationic ammonium groups of the surfactants with anionic groups of E. coli, resulting in loss of the barrier function of the outer membrane. The inner membrane then is disintegrated by the hydrophobic interaction of the surfactant hydrocarbon chains with the hydrophobic domains of the inner membrane, leading to the cytoplast leakage. The formation of micelles of these cationic oligomeric surfactants at very low concentration enables more efficient interaction with bacterial cell membrane, which endows the oligomeric surfactants with high antibacterial activity.

  18. Selective lowering of synapsins induced by oligomeric α-synuclein exacerbates memory deficits.

    Science.gov (United States)

    Larson, Megan E; Greimel, Susan J; Amar, Fatou; LaCroix, Michael; Boyle, Gabriel; Sherman, Mathew A; Schley, Hallie; Miel, Camille; Schneider, Julie A; Kayed, Rakez; Benfenati, Fabio; Lee, Michael K; Bennett, David A; Lesné, Sylvain E

    2017-06-06

    Mounting evidence indicates that soluble oligomeric forms of amyloid proteins linked to neurodegenerative disorders, such as amyloid-β (Aβ), tau, or α-synuclein (αSyn) might be the major deleterious species for neuronal function in these diseases. Here, we found an abnormal accumulation of oligomeric αSyn species in AD brains by custom ELISA, size-exclusion chromatography, and nondenaturing/denaturing immunoblotting techniques. Importantly, the abundance of αSyn oligomers in human brain tissue correlated with cognitive impairment and reductions in synapsin expression. By overexpressing WT human αSyn in an AD mouse model, we artificially enhanced αSyn oligomerization. These bigenic mice displayed exacerbated Aβ-induced cognitive deficits and a selective decrease in synapsins. Following isolation of various soluble αSyn assemblies from transgenic mice, we found that in vitro delivery of exogenous oligomeric αSyn but not monomeric αSyn was causing a lowering in synapsin-I/II protein abundance. For a particular αSyn oligomer, these changes were either dependent or independent on endogenous αSyn expression. Finally, at a molecular level, the expression of synapsin genes SYN1 and SYN2 was down-regulated in vivo and in vitro by αSyn oligomers, which decreased two transcription factors, cAMP response element binding and Nurr1, controlling synapsin gene promoter activity. Overall, our results demonstrate that endogenous αSyn oligomers can impair memory by selectively lowering synapsin expression.

  19. Antitumor-promoting activity of oligomeric proanthocyanidins in mouse epidermis in vivo

    Science.gov (United States)

    Mei Xiao Gao; Elisabeth M. Perchellet; Hala U. Gali; Limarie Rodriguez; Richard W. Hemingway; Jean-Pierre Perchellet

    1994-01-01

    The flavanoid catechin and heterogenous samples of oligomeric proanthocyanidins extracted from various sources were compared for their ability to inhibit the biochemical and biological effects of 12-o-tertra-decanoylphorbol-13-acetate (TPA) in mouse epidermis in vivo. Topical applications of catechin fail to alter the hydroperoxide response to TPA but inhibit the...

  20. Monitoring receptor oligomerization by line-scan fluorescence cross-correlation spectroscopy

    NARCIS (Netherlands)

    Hink, M.A.; Postma, M.; Conn, P.M.

    2013-01-01

    Membrane-localized receptor proteins are involved in many signaling cascades, and diffusion and oligomerization are key processes controlling their activity. In order to study these processes in living cells, fluorescence fluctuation spectroscopy techniques have been developed that allow the quantif

  1. Concentration Dependent Ion-Protein Interaction Patterns Underlying Protein Oligomerization Behaviours

    Science.gov (United States)

    Batoulis, Helena; Schmidt, Thomas H.; Weber, Pascal; Schloetel, Jan-Gero; Kandt, Christian; Lang, Thorsten

    2016-04-01

    Salts and proteins comprise two of the basic molecular components of biological materials. Kosmotropic/chaotropic co-solvation and matching ion water affinities explain basic ionic effects on protein aggregation observed in simple solutions. However, it is unclear how these theories apply to proteins in complex biological environments and what the underlying ionic binding patterns are. Using the positive ion Ca2+ and the negatively charged membrane protein SNAP25, we studied ion effects on protein oligomerization in solution, in native membranes and in molecular dynamics (MD) simulations. We find that concentration-dependent ion-induced protein oligomerization is a fundamental chemico-physical principle applying not only to soluble but also to membrane-anchored proteins in their native environment. Oligomerization is driven by the interaction of Ca2+ ions with the carboxylate groups of aspartate and glutamate. From low up to middle concentrations, salt bridges between Ca2+ ions and two or more protein residues lead to increasingly larger oligomers, while at high concentrations oligomers disperse due to overcharging effects. The insights provide a conceptual framework at the interface of physics, chemistry and biology to explain binding of ions to charged protein surfaces on an atomistic scale, as occurring during protein solubilisation, aggregation and oligomerization both in simple solutions and membrane systems.

  2. Styrene oligomerization as a molecular probe reaction for Brønsted acidity at the nanoscale

    NARCIS (Netherlands)

    Aramburo Corrales, Luis; Wirick, Sue; Miedema, P.S.; Buurmans, I.L.C.; de Groot, F.M.F.; Weckhuysen, B.M.

    2012-01-01

    The Brønsted acid-catalyzed oligomerization of 4-fluorostyrene has been studied on a series ofH-ZSM-5 zeolite powders, steamed under different conditions, with a combination of UV-Vismicro-spectroscopy and Scanning Transmission X-ray Microscopy (STXM). UV-Vis microspectroscopyand STXM have been used

  3. Oligomerization of a Glucagon-like Peptide 1 Analog: Bridging Experiment and Simulations

    DEFF Research Database (Denmark)

    Frederiksen, Tine Maja; Sønderby, Pernille; Ryberg, Line A.

    2015-01-01

    The glucagon-like peptide 1 (GLP-1) analog, liraglutide, is a GLP-1 agonist and is used in the treatment of type-2 diabetes mellitus and obesity. From a pharmaceutical perspective, it is important to know the oligomerization state of liraglutide with respect to stability. Compared to GLP-1...

  4. Phenolic compounds prevent the oligomerization of α-synuclein and reduce synaptic toxicity.

    Science.gov (United States)

    Takahashi, Ryoichi; Ono, Kenjiro; Takamura, Yusaku; Mizuguchi, Mineyuki; Ikeda, Tokuhei; Nishijo, Hisao; Yamada, Masahito

    2015-09-01

    Lewy bodies, mainly composed of α-synuclein (αS), are pathological hallmarks of Parkinson's disease and dementia with Lewy bodies. Epidemiological studies showed that green tea consumption or habitual intake of phenolic compounds reduced Parkinson's disease risk. We previously reported that phenolic compounds inhibited αS fibrillation and destabilized preformed αS fibrils. Cumulative evidence suggests that low-order αS oligomers are neurotoxic and critical species in the pathogenesis of α-synucleinopathies. To develop disease modifying therapies for α-synucleinopathies, we examined effects of phenolic compounds (myricetin (Myr), curcumin, rosmarinic acid (RA), nordihydroguaiaretic acid, and ferulic acid) on αS oligomerization. Using methods such as photo-induced cross-linking of unmodified proteins, circular dichroism spectroscopy, the electron microscope, and the atomic force microscope, we showed that Myr and RA inhibited αS oligomerization and secondary structure conversion. The nuclear magnetic resonance analysis revealed that Myr directly bound to the N-terminal region of αS, whereas direct binding of RA to monomeric αS was not detected. Electrophysiological assays for long-term potentiation in mouse hippocampal slices revealed that Myr and RA ameliorated αS synaptic toxicity by inhibition of αS oligomerization. These results suggest that Myr and RA prevent the αS aggregation process, reducing the neurotoxicity of αS oligomers. To develop disease modifying therapies for α-synucleinopathies, we examined effects of phenolic compounds on α-synuclein (αS) oligomerization. Phenolic compounds, especially Myricetin (Myr) and Rosmarinic acid (RA), inhibited αS oligomerization and secondary structure conversion. Myr and RA ameliorated αS synaptic toxicity on the experiment of long-term potentiation. Our results suggest that Myr and RA prevent αS aggregation process and reduce the neurotoxicity of αS oligomers. Phenolic compounds are good

  5. Confocal Spectroscopy to Study Dimerization, Oligomerization and Aggregation of Proteins: A Practical Guide.

    Science.gov (United States)

    Gambin, Yann; Polinkovsky, Mark; Francois, Bill; Giles, Nichole; Bhumkar, Akshay; Sierecki, Emma

    2016-04-30

    Protein self-association is a key feature that can modulate the physiological role of proteins or lead to deleterious effects when uncontrolled. Protein oligomerization is a simple way to modify the activity of a protein, as the modulation of binding interfaces allows for self-activation or inhibition, or variation in the selectivity of binding partners. As such, dimerization and higher order oligomerization is a common feature in signaling proteins, for example, and more than 70% of enzymes have the potential to self-associate. On the other hand, protein aggregation can overcome the regulatory mechanisms of the cell and can have disastrous physiological effects. This is the case in a number of neurodegenerative diseases, where proteins, due to mutation or dysregulation later in life, start polymerizing and often fibrillate, leading to the creation of protein inclusion bodies in cells. Dimerization, well-defined oligomerization and random aggregation are often difficult to differentiate and characterize experimentally. Single molecule "counting" methods are particularly well suited to the study of self-oligomerization as they allow observation and quantification of behaviors in heterogeneous conditions. However, the extreme dilution of samples often causes weak complexes to dissociate, and rare events can be overlooked. Here, we discuss a straightforward alternative where the principles of single molecule detection are used at higher protein concentrations to quantify oligomers and aggregates in a background of monomers. We propose a practical guide for the use of confocal spectroscopy to quantify protein oligomerization status and also discuss about its use in monitoring changes in protein aggregation in drug screening assays.

  6. Small angle X-ray scattering studies of mitochondrial glutaminase C reveal extended flexible regions, and link oligomeric state with enzyme activity.

    Directory of Open Access Journals (Sweden)

    Magda Møller

    Full Text Available Glutaminase C is a key metabolic enzyme, which is unregulated in many cancer systems and believed to play a central role in the Warburg effect, whereby cancer cells undergo changes to an altered metabolic profile. A long-standing hypothesis links enzymatic activity to the protein oligomeric state, hence the study of the solution behavior in general and the oligomer state in particular of glutaminase C is important for the understanding of the mechanism of protein activation and inhibition. In this report, this is extensively investigated in correlation to enzyme concentration or phosphate level, using a high-throughput microfluidic-mixing chip for the SAXS data collection, and we confirm that the oligomeric state correlates with activity. The in-depth solution behavior analysis further reveals the structural behavior of flexible regions of the protein in the dimeric, tetrameric and octameric state and investigates the C-terminal influence on the enzyme solution behavior. Our data enable SAXS-based rigid body modeling of the full-length tetramer states, thereby presenting the first ever experimentally derived structural model of mitochondrial glutaminase C including the N- and C-termini of the enzyme.

  7. Play vs. Procedures

    DEFF Research Database (Denmark)

    Hammar, Emil

    Through the theories of play by Gadamer (2004) and Henricks (2006), I will show how the relationship between play and game can be understood as dialectic and disruptive, thus challenging understandings of how the procedures of games determine player activity and vice versa. As such, I posit some...... analytical consequences for understandings of digital games as procedurally fixed (Boghost, 2006; Flannagan, 2009; Bathwaite & Sharp, 2010). That is, if digital games are argued to be procedurally fixed and if play is an appropriative and dialectic activity, then it could be argued that the latter affects...

  8. SLC30A3 (ZnT3 oligomerization by dityrosine bonds regulates its subcellular localization and metal transport capacity.

    Directory of Open Access Journals (Sweden)

    Gloria Salazar

    Full Text Available Non-covalent and covalent homo-oligomerization of membrane proteins regulates their subcellular localization and function. Here, we described a novel oligomerization mechanism affecting solute carrier family 30 member 3/zinc transporter 3 (SLC30A3/ZnT3. Oligomerization was mediated by intermolecular covalent dityrosine bonds. Using mutagenized ZnT3 expressed in PC12 cells, we identified two critical tyrosine residues necessary for dityrosine-mediated ZnT3 oligomerization. ZnT3 carrying the Y372F mutation prevented ZnT3 oligomerization, decreased ZnT3 targeting to synaptic-like microvesicles (SLMVs, and decreased resistance to zinc toxicity. Strikingly, ZnT3 harboring the Y357F mutation behaved as a "gain-of-function" mutant as it displayed increased ZnT3 oligomerization, targeting to SLMVs, and increased resistance to zinc toxicity. Single and double tyrosine ZnT3 mutants indicate that the predominant dimeric species is formed between tyrosine 357 and 372. ZnT3 tyrosine dimerization was detected under normal conditions and it was enhanced by oxidative stress. Covalent species were also detected in other SLC30A zinc transporters localized in different subcellular compartments. These results indicate that covalent tyrosine dimerization of a SLC30A family member modulates its subcellular localization and zinc transport capacity. We propose that dityrosine-dependent membrane protein oligomerization may regulate the function of diverse membrane protein in normal and disease states.

  9. BAX insertion, oligomerization, and outer membrane permeabilization in brain mitochondria: role of permeability transition and SH-redox regulation

    Science.gov (United States)

    Brustovetsky, Tatiana; Li, Tsyregma; Yang, Youyun; Zhang, Jiang-Ting; Antonsson, Bruno; Brustovetsky, Nickolay

    2010-01-01

    BAX cooperates with truncated BID (tBID) and Ca2+ in permeabilizing the outer mitochondrial membrane (OMM) and releasing mitochondrial apoptogenic proteins. The mechanisms of this cooperation are still unclear. Here we show that in isolated brain mitochondria, recombinant BAX readily self-integrates/oligomerizes in the OMM but produces only a minuscule release of cytochrome c, indicating that BAX insertion/oligomerization in the OMM does not always lead to massive OMM permeabilization. Ca2+ in a mitochondrial permeability transition (mPT)-dependent and recombinant tBID in an mPT-independent manner promoted BAX insertion/oligomerization in the OMM and augmented cytochrome c release. Neither tBID nor Ca2+ induced BAX oligomerization in the solution without mitochondria, suggesting that BAX oligomerization required interaction with the organelles and followed rather than preceded BAX insertion in the OMM. Recombinant Bcl-xL failed to prevent BAX insertion/oligomerization in the OMM but strongly attenuated cytochrome c release. On the other hand, a reducing agent, dithiothreitol (DTT), inhibited BAX insertion/oligomerization augmented by tBID or Ca2+ and suppressed the BAX-mediated release of cytochrome c and Smac/DIABLO but failed to inhibit Ca2+-induced swelling. Altogether, these data suggest that in brain mitochondria, BAX insertion/oligomerization can be dissociated from OMM permeabilization and that tBID and Ca2+ stimulate BAX insertion/oligomerization and BAX-mediated OMM permeabilization by different mechanisms involving mPT induction and modulation of the SH-redox state. PMID:20655869

  10. Play and Power

    DEFF Research Database (Denmark)

    The power of play, so central to psychoanalytic theory and practice, is conjoined to the social psychological or socio-politically coloured concept of power, giving rise to many fruitful discussions of how these concepts manifest themselves in clinical work with children, groups and adults....... The inspiration for this book was the 3-section EFPP conference in Copenhagen in May 2007 with the main theme "Play and Power". At the conference and in the book, this theme is presented both inside and outside the therapeutic space. It is amply illustrated in clinical cases from individual psychotherapies....... Play and power are also explored in the broader context of the community, however. In relation to society at large, psychoanalytic psychotherapy has important contributions to offer society, and we need playful creativity and power to bring forward our knowledge about it....

  11. Synthesis of Nonionic Oligomeric Manganese(Ⅱ) Complexes and Investigation of Their Toxicity and Τ1-Relaxation Enhancement

    Institute of Scientific and Technical Information of China (English)

    YU Kai-chao; LI Ying-xia; ZHOU Jin-lan; DING Shang-wu; YE Chao-hui

    2005-01-01

    Six nonionic oligomeric manganese(Ⅱ) complexes with oligomeric phosphate-polyglycol-EDTA ester ligands were synthesized and characterized. The longitudinal relaxivities of these complexes were measured. One of these complexes, which showed the highest relaxivity, was chosen to be used in the acute toxicity test and the Τ1-weighted imaging experiment. It has been found that compared to Gd-DTPA, this nonionic oligomeric Mn(Ⅱ) complex exhibits no acute toxicity, generates highly enhanced MRI signals and increases the intention time in the rat liver tissue.

  12. DNA structure modulates the oligomerization properties of the AAV initiator protein Rep68.

    Directory of Open Access Journals (Sweden)

    Jorge Mansilla-Soto

    2009-07-01

    Full Text Available Rep68 is a multifunctional protein of the adeno-associated virus (AAV, a parvovirus that is mostly known for its promise as a gene therapy vector. In addition to its role as initiator in viral DNA replication, Rep68 is essential for site-specific integration of the AAV genome into human chromosome 19. Rep68 is a member of the superfamily 3 (SF3 helicases, along with the well-studied initiator proteins simian virus 40 large T antigen (SV40-LTag and bovine papillomavirus (BPV E1. Structurally, SF3 helicases share two domains, a DNA origin interaction domain (OID and an AAA(+ motor domain. The AAA(+ motor domain is also a structural feature of cellular initiators and it functions as a platform for initiator oligomerization. Here, we studied Rep68 oligomerization in vitro in the presence of different DNA substrates using a variety of biophysical techniques and cryo-EM. We found that a dsDNA region of the AAV origin promotes the formation of a complex containing five Rep68 subunits. Interestingly, non-specific ssDNA promotes the formation of a double-ring Rep68, a known structure formed by the LTag and E1 initiator proteins. The Rep68 ring symmetry is 8-fold, thus differing from the hexameric rings formed by the other SF3 helicases. However, similiar to LTag and E1, Rep68 rings are oriented head-to-head, suggesting that DNA unwinding by the complex proceeds bidirectionally. This novel Rep68 quaternary structure requires both the DNA binding and AAA(+ domains, indicating cooperativity between these regions during oligomerization in vitro. Our study clearly demonstrates that Rep68 can oligomerize through two distinct oligomerization pathways, which depend on both the DNA structure and cooperativity of Rep68 domains. These findings provide insight into the dynamics and oligomeric adaptability of Rep68 and serve as a step towards understanding the role of this multifunctional protein during AAV DNA replication and site-specific integration.

  13. Saturated Fatty Acid Induces Insulin Resistance Partially Through Nucleotide-binding Oligomerization Domain 1 Signaling Pathway in Adipocytes

    Institute of Scientific and Technical Information of China (English)

    Yi-jun Zhou; Yin-si Tang; Yu-ling Song; Ai Li; Hui Zhou; Yan Li

    2013-01-01

    Objective To investigate the potential role of nucleotide-binding oligomerization domain 1 (NOD1), a component of the innate immune system, in mediating lipid-induced insulin resistance in adipocytes. Methods Adipocytes from Toll-like receptor 4 deficiency mice were used for stimulation experiments. The effect of oleate/palmitate mixture on nuclear factor-κB (NF-κB) activation was analyzed by reporter plasmid assay. The release of proinflammatory chemokine/cytokines production was determined by using real-time PCR. Insulin-stimulated glucose uptake was measured by 2-deoxy-D-[3H] glucose uptake assay. Chemokine/cytokine expression and glucose uptake in adipocytes transfected with small interfering RNA (siRNA) targeting NOD1 upon fatty acids treatment were analyzed. Results Oleate/palmitate mixture activated the NF-κB pathway and induced interleukin-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1 mRNA expressions in adipocytes from mice deficient in Toll-like receptor 4, and these effects were blocked by siRNA targeting NOD1. Furthermore, saturated fatty acids decreased the ability of insulin-stimulated glucose uptake. Importantly, siRNA targeting NOD1 partially reversed saturated fatty acid-induced suppression of insulin-induced glucose uptake. Conclusion NOD1 might play an important role in saturated fatty acid-induced insulin resistance in adipocytes, suggesting a mechanism by which reduced NOD1 activity confers beneficial effects on insulin action.

  14. Interplay of histidine residues of the Alzheimer’s disease Aβ peptide governs its Zn-induced oligomerization

    Science.gov (United States)

    Istrate, Andrey N.; Kozin, Sergey A.; Zhokhov, Sergey S.; Mantsyzov, Alexey B.; Kechko, Olga I.; Pastore, Annalisa; Makarov, Alexander A.; Polshakov, Vladimir I.

    2016-02-01

    Conformational changes of Aβ peptide result in its transformation from native monomeric state to the toxic soluble dimers, oligomers and insoluble aggregates that are hallmarks of Alzheimer’s disease (AD). Interactions of zinc ions with Aβ are mediated by the N-terminal Aβ1–16 domain and appear to play a key role in AD progression. There is a range of results indicating that these interactions trigger the Aβ plaque formation. We have determined structure and functional characteristics of the metal binding domains derived from several Aβ variants and found that their zinc-induced oligomerization is governed by conformational changes in the minimal zinc binding site 6HDSGYEVHH14. The residue H6 and segment 11EVHH14, which are part of this site are crucial for formation of the two zinc-mediated interaction interfaces in Aβ. These structural determinants can be considered as promising targets for rational design of the AD-modifying drugs aimed at blocking pathological Aβ aggregation.

  15. Fouling behaviors of polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes for engineering osmosis processes

    KAUST Repository

    Chen, Sicong

    2014-02-01

    This paper investigated the individual effects of reverse salt flux and permeate flux on fouling behaviors of as-spun and annealed polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes under forward osmosis (FO) and pressure retarded osmosis (PRO) processes. Two types of membrane fouling had been studied; namely, inorganic fouling (CaSO4·2H2O gypsum scaling) during FO operations and organic fouling (sodium alginate fouling) during PRO operations. It is found that gypsum scaling on the membrane surface may be inhibited and even eliminated with an increase in reverse MgCl2 flux due to competitive formations of MgSO4° and CaSO4·2H2O. In contrast, the increase of reverse NaCl flux exhibits a slight enhancement on alginate fouling in both FO and PRO processes. Comparing to the reverse salt flux, the permeate flux always plays a dominant role in fouling. Therefore, lesser fouling has been observed on the membrane surface under the pressurized PRO process than FO process because the reduced initial flux mitigates the fouling phenomena more significantly than the enhancement caused by an increase in reverse NaCl flux. © 2013 Elsevier B.V.

  16. Can play be defined?

    DEFF Research Database (Denmark)

    Eichberg, Henning

    2015-01-01

    Can play be defined? There is reason to raise critical questions about the established academic demand that at phenomenon – also in humanist studies – should first of all be defined, i.e. de-lineated and by neat lines limited to a “little box” that can be handled. The following chapter develops t....... Human beings can very well understand play – or whatever phenomenon in human life – without defining it........ The academic imperative of definition seems to be linked to the positivistic attempts – and produces sometimes monstrous definitions. Have they any philosophical value for our knowledge of what play is? Definition is not a universal instrument of knowledge-building, but a culturally specific construction...

  17. Playing and gaming

    DEFF Research Database (Denmark)

    Karoff, Helle Skovbjerg; Ejsing-Duun, Stine; Hanghøj, Thorkild

    2013-01-01

    The paper develops an approach of playing and gaming activities through the perspective of both activities as mood activities . The point of departure is that a game - is a tool with which we, through our practices, achieve different moods. This based on an empirical study of children's everyday...... lives, where the differences emerge through actual practices, i.e. through the creation of meaning in the specific situations. The overall argument is that it is not that important whether it is a playing or a gaming activity - it is however crucial to be aware of how moods occur and what their optimal...... dimensions: practices and moods. Practice is the concept of all the doing in the activities. Moods are the particular concept of sense and feeling of being, which is what we are drawn to when we are playing or gaming....

  18. Playing and gaming

    DEFF Research Database (Denmark)

    Karoff, Helle Skovbjerg; Ejsing-Duun, Stine; Hanghøj, Thorkild

    2013-01-01

    The paper develops an approach of playing and gaming activities through the perspective of both activities as mood activities . The point of departure is that a game - is a tool with which we, through our practices, achieve different moods. This based on an empirical study of children's everyday...... lives, where the differences emerge through actual practices, i.e. through the creation of meaning in the specific situations. The overall argument is that it is not that important whether it is a playing or a gaming activity - it is however crucial to be aware of how moods occur and what their optimal...... dimensions: practices and moods. Practice is the concept of all the doing in the activities. Moods are the particular concept of sense and feeling of being, which is what we are drawn to when we are playing or gaming....

  19. General game playing

    CERN Document Server

    Genesereth, Michael

    2014-01-01

    General game players are computer systems able to play strategy games based solely on formal game descriptions supplied at ""runtime"" (n other words, they don't know the rules until the game starts). Unlike specialized game players, such as Deep Blue, general game players cannot rely on algorithms designed in advance for specific games; they must discover such algorithms themselves. General game playing expertise depends on intelligence on the part of the game player and not just intelligence of the programmer of the game player.GGP is an interesting application in its own right. It is intell

  20. Playful Collaboration (or Not)

    DEFF Research Database (Denmark)

    Bogers, Marcel; Sproedt, Henrik

    2011-01-01

    also be conducive to deep learning. As such, a game can engage different dimensions of learning and embed elements of active, collaborative, cooperative and problem-based learning. Building on this logic, we present an exploratory case study of the use of a particular board game in a class of a course......This paper explores how games and play, which are deeply rooted in human beings as a way to learn and interact, can be used to teach certain concepts and practices related to open collaborative innovation. We discuss how playing games can be a source of creativity, imagination and fun, while it can...

  1. Five recent play dates

    DEFF Research Database (Denmark)

    Abildgaard, Mette Simonsen; Birkbak, Andreas; Jensen, Torben Elgaard

    2017-01-01

    An advantage of the playground metaphor is that it comes with the activity of going out on ‘play dates’ and developing friendships. In such playful relationships, there is always something at stake, but the interaction is also fun and inherently exploratory. In the following, we take a tour of five...... recent collaborative projects that the TANTlab has participated in. The projects differ widely and testify to different experiences with collaboration and intervention – from a data print on obesity with other researchers to a Facebook-driven intervention in Aalborg municipality’s primary school reform...

  2. Screening of Drugs Inhibiting In vitro Oligomerization of Cu/Zn-Superoxide Dismutase with a Mutation Causing Amyotrophic Lateral Sclerosis.

    Science.gov (United States)

    Anzai, Itsuki; Toichi, Keisuke; Tokuda, Eiichi; Mukaiyama, Atsushi; Akiyama, Shuji; Furukawa, Yoshiaki

    2016-01-01

    Dominant mutations in Cu/Zn-superoxide dismutase (SOD1) gene have been shown to cause a familial form of amyotrophic lateral sclerosis (SOD1-ALS). A major pathological hallmark of this disease is abnormal accumulation of mutant SOD1 oligomers in the affected spinal motor neurons. While no effective therapeutics for SOD1-ALS is currently available, SOD1 oligomerization will be a good target for developing cures of this disease. Recently, we have reproduced the formation of SOD1 oligomers abnormally cross-linked via disulfide bonds in a test tube. Using our in vitro model of SOD1 oligomerization, therefore, we screened 640 FDA-approved drugs for inhibiting the oligomerization of SOD1 proteins, and three effective classes of chemical compounds were identified. Those hit compounds will provide valuable information on the chemical structures for developing a novel drug candidate suppressing the abnormal oligomerization of mutant SOD1 and possibly curing the disease.

  3. Accelerated parabolic Radon domain 2D adaptive multiple subtraction with fast iterative shrinkage thresholding algorithm and its application in parabolic Radon domain hybrid demultiple method

    Science.gov (United States)

    Li, Zhong-xiao; Li, Zhen-chun

    2017-08-01

    Adaptive multiple subtraction is an important step for successfully conducting surface-related multiple elimination in marine seismic exploration. 2D adaptive multiple subtraction conducted in the parabolic Radon domain has been proposed to better separate primaries and multiples than 2D adaptive multiple subtraction conducted in the time-offset domain. Additionally, the parabolic Radon domain hybrid demultiple method combining parabolic Radon filtering and parabolic Radon domain 2D adaptive multiple subtraction can better remove multiples than the cascaded demultiple method using time-offset domain 2D adaptive multiple subtraction and the parabolic Radon transform method sequentially. To solve the matching filter in the optimization problem with L1 norm minimization constraint of primaries, traditional parabolic Radon domain 2D adaptive multiple subtraction uses the iterative reweighted least squares (IRLS) algorithm, which is computationally expensive for solving a weighted LS inversion in each iteration. In this paper we introduce the fast iterative shrinkage thresholding algorithm (FISTA) as a faster alternative to the IRLS algorithm for parabolic Radon domain 2D adaptive multiple subtraction. FISTA uses the shrinkage-thresholding operator to promote the sparsity of estimated primaries and solves the 2D matching filter with iterative steps. FISTA based parabolic Radon domain 2D adaptive multiple subtraction reduces the computation time effectively while achieving similar accuracy compared with IRLS based parabolic Radon domain 2D adaptive multiple subtraction. Additionally, the provided examples show that FISTA based parabolic Radon domain 2D adaptive multiple subtraction can better separate primaries and multiples than FISTA based time-offset domain 2D adaptive multiple subtraction. Furthermore, we introduce FISTA based parabolic Radon domain 2D adaptive multiple subtraction into the parabolic Radon domain hybrid demultiple method to improve its computation

  4. The Activity of Play

    DEFF Research Database (Denmark)

    Pichlmair, Martin

    2016-01-01

    This paper presents Activity Theory as a framework for understanding the action of playing games with the intention of building a foundation for the creation of new game design tools and methods. Activity Theory, an epistemological framework rooted in Soviet psychology of the first half of the 20...

  5. Playing the Role

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The G20 London summit made history. While applauding the summit’s productive communique, Ni Xiaoling, senior financial observer with Xinhua News Agency, warns of the gap between the greater responsibilities the International Monetary Fund shoulders and its limited capabilities to play the role of coordinator in economic globalization.

  6. Abstraction through Game Play

    Science.gov (United States)

    Avraamidou, Antri; Monaghan, John; Walker, Aisha

    2012-01-01

    This paper examines the computer game play of an 11-year-old boy. In the course of building a virtual house he developed and used, without assistance, an artefact and an accompanying strategy to ensure that his house was symmetric. We argue that the creation and use of this artefact-strategy is a mathematical abstraction. The discussion…

  7. Mobilities at Play

    DEFF Research Database (Denmark)

    Ungruhe, Christian

    2017-01-01

    -level perspective there is still an analytical gap between the ambitions and experiences of migrating players and economic power relations at play on the one hand and the socio-cultural embedding of the transnational connections in football migration on the other. In order to understand why and how football...

  8. Play's Importance in School

    Science.gov (United States)

    Sandberg, Anette; Heden, Rebecca

    2011-01-01

    The purpose of this study is to contribute knowledge on and gain an understanding of elementary school teachers' perspectives on the function of play in children's learning processes. The study is qualitative with a hermeneutical approach and has George Herbert Mead as a theoretical frame of reference. Interviews have been carried out with seven…

  9. Play framework essentials

    CERN Document Server

    Richard-Foy, Julien

    2014-01-01

    This book targets Java and Scala developers who already have some experience in web development and who want to master Play framework quickly and efficiently. This book assumes you have a good level of knowledge and understanding of efficient Java and Scala code.

  10. A Significant Play

    Institute of Scientific and Technical Information of China (English)

    梁海光; 陈明

    2002-01-01

    Yesterday evening, I went to see a play. It was really significant. It was about Zheng Xiaoyue, a very clever and diligent middle school student. Unfortunately, her mother died when she and her brother were very young. Her father was out of work and,

  11. Three-Dimensional Models of the Oligomeric Human Asialoglycoprotein Receptor (ASGP-R

    Directory of Open Access Journals (Sweden)

    Anna Maria Bianucci

    2010-10-01

    Full Text Available The work presented here is aimed at suggesting plausible hypotheses for functional oligomeric forms of the human asialoglycoprotein receptor (ASGP-R, by applying a combination of different computational techniques. The functional ASGP-R is a hetero-oligomer, that comprises of several subunits of two different kinds (H1 and H2, which are highly homologous. Its stoichiometry is still unknown. An articulated step-wise modeling protocol was used in order to build the receptor model in a minimal oligomeric form, necessary for it to bind multi-antennary carbohydrate ligands. The ultimate target of the study is to contribute to increasing the knowledge of interactions between the human ASGP-R and carbohydrate ligands, at the molecular level, pertinent to applications in the field of hepatic tissue engineering.

  12. Near-Field Optical Microscopy of Defects in Cholesteric Oligomeric Liquid Crystal Films

    Energy Technology Data Exchange (ETDEWEB)

    Lukishova, S.G.; Schmid, A.W.

    2006-08-18

    This paper describes formation of 2-D hexagonal structures with a periodicity ~0.5-0.8 um in the defects of thin films of cholesteric oligomeric liquid crystals prepared by the evaporation of the solvent from the oligomer solution on the substrate. These regular arrays were observed by scanning near-field optical and concurrent atomic force microscopy. The mechanisms considered are both Benard-Marangoni and buoyancy conventions induced by solvent evaporation and air-bubble creation around the condensed water droplets from the air during evaporative cooling. Hexagonal structures prepared by this method can be used in photonic devices for emission enhancement, for instance, in liquid crystal lasers and single photon sources with oligomeric liquid crystal hosts.

  13. Structural polymorphism in the N-terminal oligomerization domain of NPM1.

    Science.gov (United States)

    Mitrea, Diana M; Grace, Christy R; Buljan, Marija; Yun, Mi-Kyung; Pytel, Nicholas J; Satumba, John; Nourse, Amanda; Park, Cheon-Gil; Madan Babu, M; White, Stephen W; Kriwacki, Richard W

    2014-03-25

    Nucleophosmin (NPM1) is a multifunctional phospho-protein with critical roles in ribosome biogenesis, tumor suppression, and nucleolar stress response. Here we show that the N-terminal oligomerization domain of NPM1 (Npm-N) exhibits structural polymorphism by populating conformational states ranging from a highly ordered, folded pentamer to a highly disordered monomer. The monomer-pentamer equilibrium is modulated by posttranslational modification and protein binding. Phosphorylation drives the equilibrium in favor of monomeric forms, and this effect can be reversed by Npm-N binding to its interaction partners. We have identified a short, arginine-rich linear motif in NPM1 binding partners that mediates Npm-N oligomerization. We propose that the diverse functional repertoire associated with NPM1 is controlled through a regulated unfolding mechanism signaled through posttranslational modifications and intermolecular interactions.

  14. Crystal structure of listeriolysin O reveals molecular details of oligomerization and pore formation

    Science.gov (United States)

    Köster, Stefan; van Pee, Katharina; Hudel, Martina; Leustik, Martin; Rhinow, Daniel; Kühlbrandt, Werner; Chakraborty, Trinad; Yildiz, Özkan

    2014-04-01

    Listeriolysin O (LLO) is an essential virulence factor of Listeria monocytogenes that causes listeriosis. Listeria monocytogenes owes its ability to live within cells to the pH- and temperature-dependent pore-forming activity of LLO, which is unique among cholesterol-dependent cytolysins. LLO enables the bacteria to cross the phagosomal membrane and is also involved in activation of cellular processes, including the modulation of gene expression or intracellular Ca2+ oscillations. Neither the pore-forming mechanism nor the mechanisms triggering the signalling processes in the host cell are known in detail. Here, we report the crystal structure of LLO, in which we identified regions important for oligomerization and pore formation. Mutants were characterized by determining their haemolytic and Ca2+ uptake activity. We analysed the pore formation of LLO and its variants on erythrocyte ghosts by electron microscopy and show that pore formation requires precise interface interactions during toxin oligomerization on the membrane.

  15. Effect of acid density of HZSM-5 on the oligomerization of ethylene in FCC dry gas

    Institute of Scientific and Technical Information of China (English)

    Xue Ding; Shan Geng; Chunyi Li; Chaohe Yang; Guohui Wang

    2009-01-01

    The oligomerization of ethylene in FCC dry gas over HZSM-5 catalyst with different Si/Al2 ratios was studied. The effect of acid density of catalyst on the oligomerization of ethylene was discussed. By increasing the acid density of catalyst, ethylene conversion showed a linear increase, while the yields of olefins decreased when the acid density of catalyst exceeded 0.14 mmolNH3/g owing to a promotion of hydrogen transfer reaction. Through comparing the average distance between acid sites on catalyst with kinetic diameters of olefins, it was found that the dimerization of ethylene was not restrained by the sparse distribution of acid sites, while the hydrogen transfer reaction of C3 and C4 olefins was limited. On these bases, a conclusion is proposed that the dimerization of ethylene proceeded via Eley-Rideal mechanism, while the hydrogen transfer reaction of C3 and C4 olefins followed the Langmuir-Hinshelwood mechanism.

  16. Molecular basis for oligomeric-DNA binding and episome maintenance by KSHV LANA.

    Directory of Open Access Journals (Sweden)

    John F Domsic

    Full Text Available LANA is the KSHV-encoded terminal repeat binding protein essential for viral replication and episome maintenance during latency. We have determined the X-ray crystal structure of LANA C-terminal DNA binding domain (LANADBD to reveal its capacity to form a decameric ring with an exterior DNA binding surface. The dimeric core is structurally similar to EBV EBNA1 with an N-terminal arm that regulates DNA binding and is required for replication function. The oligomeric interface between LANA dimers is dispensable for single site DNA binding, but is required for cooperative DNA binding, replication function, and episome maintenance. We also identify a basic patch opposite of the DNA binding surface that is responsible for the interaction with BRD proteins and contributes to episome maintenance function. The structural features of LANADBD suggest a novel mechanism of episome maintenance through DNA-binding induced oligomeric assembly.

  17. Small Angle X-Ray Scattering Studies of Mitochondrial Glutaminase C Reveal Extended Flexible Regions, and Link Oligomeric State with Enzyme Activity

    DEFF Research Database (Denmark)

    Møller, M.; Nielsen, Søren Skou; Ramachandran, Siddharth;

    2013-01-01

    Glutaminase C is a key metabolic enzyme, which is unregulated in many cancer systems and believed to play a central role in the Warburg effect, whereby cancer cells undergo changes to an altered metabolic profile. A long-standing hypothesis links enzymatic activity to the protein oligomeric state......, hence the study of the solution behavior in general and the oligomer state in particular of glutaminase C is important for the understanding of the mechanism of protein activation and inhibition. In this report, this is extensively investigated in correlation to enzyme concentration or phosphate level...... state and investigates the C-terminal influence on the enzyme solution behavior. Our data enable SAXS-based rigid body modeling of the full-length tetramer states, thereby presenting the first ever experimentally derived structural model of mitochondrial glutaminase C including the N- and C...

  18. Three-Dimensional Models of the Oligomeric Human Asialoglycoprotein Receptor (ASGP-R)

    OpenAIRE

    Anna Maria Bianucci; Ilaria Massarelli; Federica Chiellini; Emo Chiellini

    2010-01-01

    The work presented here is aimed at suggesting plausible hypotheses for functional oligomeric forms of the human asialoglycoprotein receptor (ASGP-R), by applying a combination of different computational techniques. The functional ASGP-R is a hetero-oligomer, that comprises of several subunits of two different kinds (H1 and H2), which are highly homologous. Its stoichiometry is still unknown. An articulated step-wise modeling protocol was used in order to build the receptor model in a minimal...

  19. Alternative Models of Iron and Cobalt Catalysts for Ethylene Oligomerization and Polymerization

    Institute of Scientific and Technical Information of China (English)

    Katrin; Wedeking; Sherrif; Adewuyi; Maliha; Asma; Igor; Vystorop; Saliu; Amolegbe; Elena; Novikova

    2007-01-01

    1 Results Great progresses have been made in the field of transition metal-based complexes as catalytic precursors for olefin oligomerization and polymerization,in which the core subjects will remain as "know and how" to develop novel catalysts both in academic and industrial consideration.The key advantage of iron and cobalt catalyst for ethylene polymerization is to produce vinyl-type polyethylenes.Therefore following the pioneering works of bis(imino) pyridyl iron and cobalt catalyst by Brookhart[1] ...

  20. Zn(2+) site engineering at the oligomeric interface of the dopamine transporter

    DEFF Research Database (Denmark)

    Norgaard-Nielsen, Kristine; Norregaard, Lene; Hastrup, Hanne

    2002-01-01

    of the dopamine transporter (DAT) corresponding to the external end of transmembrane segment 6. Upon binding to this site, which involves a histidine inserted in position 310 (V310H) and the endogenous Cys306 within the same DAT molecule, Zn(2+) potently inhibits [(3)H]dopamine uptake. These data provide indirect...... evidence that conformational changes critical for the translocation process may occur at the interface between two transporter molecules in the oligomeric structure....

  1. Oligomerization of DH Domain Is Essential for Dbl-Induced Transformation

    OpenAIRE

    Zhu, Kejin; Debreceni, Balazs; Bi, Feng; Zheng, Yi

    2001-01-01

    The dbl oncogene product (onco-Dbl) is the prototype member of a family of guanine nucleotide exchange factors (GEFs) for Rho GTPases. The Dbl homology (DH) domain of onco-Dbl is responsible for the GEF catalytic activity, and the DH domain, together with the immediately adjacent pleckstrin homology (PH) domain, constitutes the minimum module bearing transforming function. In the present study, we demonstrate that the onco-Dbl protein exists in oligomeric form in vitro and in cells. The oligo...

  2. Membrane Permeabilization by Oligomeric α-Synuclein: In Search of the Mechanism.

    Directory of Open Access Journals (Sweden)

    Bart D van Rooijen

    Full Text Available BACKGROUND: The question of how the aggregation of the neuronal protein α-synuclein contributes to neuronal toxicity in Parkinson's disease has been the subject of intensive research over the past decade. Recently, attention has shifted from the amyloid fibrils to soluble oligomeric intermediates in the α-synuclein aggregation process. These oligomers are hypothesized to be cytotoxic and to permeabilize cellular membranes, possibly by forming pore-like complexes in the bilayer. Although the subject of α-synuclein oligomer-membrane interactions has attracted much attention, there is only limited evidence that supports the pore formation by α-synuclein oligomers. In addition the existing data are contradictory. METHODOLOGY/PRINCIPAL FINDINGS: Here we have studied the mechanism of lipid bilayer disruption by a well-characterized α-synuclein oligomer species in detail using a number of in vitro bilayer systems and assays. Dye efflux from vesicles induced by oligomeric α-synuclein was found to be a fast all-or-none process. Individual vesicles swiftly lose their contents but overall vesicle morphology remains unaltered. A newly developed assay based on a dextran-coupled dye showed that non-equilibrium processes dominate the disruption of the vesicles. The membrane is highly permeable to solute influx directly after oligomer addition, after which membrane integrity is partly restored. The permeabilization of the membrane is possibly related to the intrinsic instability of the bilayer. Vesicles composed of negatively charged lipids, which are generally used for measuring α-synuclein-lipid interactions, were unstable to protein adsorption in general. CONCLUSIONS/SIGNIFICANCE: The dye efflux from negatively charged vesicles upon addition of α-synuclein has been hypothesized to occur through the formation of oligomeric membrane pores. However, our results show that the dye efflux characteristics are consistent with bilayer defects caused by

  3. Oligomeric state regulated trafficking of human platelet-activating factor acetylhydrolase type-II.

    Science.gov (United States)

    Monillas, Elizabeth S; Caplan, Jeffrey L; Thévenin, Anastasia F; Bahnson, Brian J

    2015-05-01

    The intracellular enzyme platelet-activating factor acetylhydrolase type-II (PAFAH-II) hydrolyzes platelet-activating factor and oxidatively fragmented phospholipids. PAFAH-II in its resting state is mainly cytoplasmic, and it responds to oxidative stress by becoming increasingly bound to endoplasmic reticulum and Golgi membranes. Numerous studies have indicated that this enzyme is essential for protecting cells from oxidative stress induced apoptosis. However, the regulatory mechanism of the oxidative stress response by PAFAH-II has not been fully resolved. Here, changes to the oligomeric state of human PAFAH-II were investigated as a potential regulatory mechanism toward enzyme trafficking. Native PAGE analysis in vitro and photon counting histogram within live cells showed that PAFAH-II is both monomeric and dimeric. A Gly-2-Ala site-directed mutation of PAFAH-II demonstrated that the N-terminal myristoyl group is required for homodimerization. Additionally, the distribution of oligomeric PAFAH-II is distinct within the cell; homodimers of PAFAH-II were localized to the cytoplasm while monomers were associated to the membranes of the endoplasmic reticulum and Golgi. We propose that the oligomeric state of PAFAH-II drives functional protein trafficking. PAFAH-II localization to the membrane is critical for substrate acquisition and effective oxidative stress protection. It is hypothesized that the balance between monomer and dimer serves as a regulatory mechanism of a PAFAH-II oxidative stress response.

  4. Recursive directional ligation by plasmid reconstruction allows rapid and seamless cloning of oligomeric genes.

    Science.gov (United States)

    McDaniel, Jonathan R; Mackay, J Andrew; Quiroz, Felipe García; Chilkoti, Ashutosh

    2010-04-12

    This paper reports a new strategy, recursive directional ligation by plasmid reconstruction (PRe-RDL), to rapidly clone highly repetitive polypeptides of any sequence and specified length over a large range of molecular weights. In a single cycle of PRe-RDL, two halves of a parent plasmid, each containing a copy of an oligomer, are ligated together, thereby dimerizing the oligomer and reconstituting a functional plasmid. This process is carried out recursively to assemble an oligomeric gene with the desired number of repeats. PRe-RDL has several unique features that stem from the use of type IIs restriction endonucleases: first, PRe-RDL is a seamless cloning method that leaves no extraneous nucleotides at the ligation junction. Because it uses type IIs endonucleases to ligate the two halves of the plasmid, PRe-RDL also addresses the major limitation of RDL in that it abolishes any restriction on the gene sequence that can be oligomerized. The reconstitution of a functional plasmid only upon successful ligation in PRe-RDL also addresses two other limitations of RDL: the significant background from self-ligation of the vector observed in RDL, and the decreased efficiency of ligation due to nonproductive circularization of the insert. PRe-RDL can also be used to assemble genes that encode different sequences in a predetermined order to encode block copolymers or append leader and trailer peptide sequences to the oligomerized gene.

  5. Rapid synthesis of cyclic oligomeric depsipeptides with positional, stereochemical, and macrocycle size distribution control.

    Science.gov (United States)

    Batiste, Suzanne M; Johnston, Jeffrey N

    2016-12-27

    Macrocyclic small molecules are attractive tools in the development of sensors, new materials, and therapeutics. Within early-stage drug discovery, they are increasingly sought for their potential to interact with broad surfaces of peptidic receptors rather than within their narrow folds and pockets. Cyclization of linear small molecule precursors is a straightforward strategy to constrain conformationally mobile motifs, but forging a macrocycle bond typically becomes more difficult at larger ring sizes. We report the development of a general approach to discrete collections of oligomeric macrocyclic depsipeptides using an oligomerization/macrocyclization process governed by a series of Mitsunobu reactions of hydroxy acid monomers. Ring sizes of 18, 24, 30, and 36 are formed in a single reaction from a didepsipeptide, whereas sizes of 24, 36, and 60 result from a tetradepsipeptide. The ring-size selectivity inherent to the approach can be modulated by salt additives that enhance the formation of specific ring sizes. Use of chemical synthesis to prepare the monomers suggests broad access to functionally and stereochemically diverse collections of natural product-like oligodepsipeptide macrocycles. Two cyclodepsipeptide natural products were prepared along with numerous unnatural oligomeric congeners to provide rapid access to discrete collections of complex macrocyclic small molecules from medium (18) to large (60) ring sizes.

  6. Phosphomimetic mutations enhance oligomerization of phospholemman and modulate its interaction with the Na/K-ATPase.

    Science.gov (United States)

    Song, Qiujing; Pallikkuth, Sandeep; Bossuyt, Julie; Bers, Donald M; Robia, Seth L

    2011-03-18

    Na/K-ATPase (NKA) activity is dynamically regulated by an inhibitory interaction with a small transmembrane protein, phospholemman (PLM). Inhibition is relieved upon PLM phosphorylation. Phosphorylation may alter how PLM interacts with NKA and/or itself, but details of these interactions are unknown. To address this, we quantified FRET between PLM and its regulatory target NKA in live cells. Phosphorylation of PLM was mimicked by mutation S63E (PKC site), S68E (PKA/PKC site), or S63E/S68E. The dependence of FRET on protein expression in live cells yielded information about the structure and binding affinity of the PLM-NKA regulatory complex. PLM phosphomimetic mutations altered the quaternary structure of the regulatory complex and reduced the apparent affinity of the PLM-NKA interaction. The latter effect was likely due to increased oligomerization of PLM phosphomimetic mutants, as suggested by PLM-PLM FRET measurements. Distance constraints obtained by FRET suggest that phosphomimetic mutations slightly alter the oligomer quaternary conformation. Photon-counting histogram measurements revealed that the major PLM oligomeric species is a tetramer. We conclude that phosphorylation of PLM increases its oligomerization into tetramers, decreases its binding to NKA, and alters the structures of both the tetramer and NKA regulatory complex.

  7. Structural basis for the oligomerization of the MADS domain transcription factor SEPALLATA3 in Arabidopsis.

    Science.gov (United States)

    Puranik, Sriharsha; Acajjaoui, Samira; Conn, Simon; Costa, Luca; Conn, Vanessa; Vial, Anthony; Marcellin, Romain; Melzer, Rainer; Brown, Elizabeth; Hart, Darren; Theißen, Günter; Silva, Catarina S; Parcy, François; Dumas, Renaud; Nanao, Max; Zubieta, Chloe

    2014-09-01

    In plants, MADS domain transcription factors act as central regulators of diverse developmental pathways. In Arabidopsis thaliana, one of the most central members of this family is SEPALLATA3 (SEP3), which is involved in many aspects of plant reproduction, including floral meristem and floral organ development. SEP3 has been shown to form homo and heterooligomeric complexes with other MADS domain transcription factors through its intervening (I) and keratin-like (K) domains. SEP3 function depends on its ability to form specific protein-protein complexes; however, the atomic level determinants of oligomerization are poorly understood. Here, we report the 2.5-Å crystal structure of a small portion of the intervening and the complete keratin-like domain of SEP3. The domains form two amphipathic alpha helices separated by a rigid kink, which prevents intramolecular association and presents separate dimerization and tetramerization interfaces comprising predominantly hydrophobic patches. Mutations to the tetramerization interface demonstrate the importance of highly conserved hydrophobic residues for tetramer stability. Atomic force microscopy was used to show SEP3-DNA interactions and the role of oligomerization in DNA binding and conformation. Based on these data, the oligomerization patterns of the larger family of MADS domain transcription factors can be predicted and manipulated based on the primary sequence. © 2014 American Society of Plant Biologists. All rights reserved.

  8. Functional foods effective for hepatitis C: Identification of oligomeric proanthocyanidin and its action mechanism

    Institute of Scientific and Technical Information of China (English)

    Yo-ichi; Ishida; Masahiko; Takeshita; Hiroaki; Kataoka

    2014-01-01

    Hepatitis C virus(HCV)is a major cause of viral hepatitis and currently infects approximately 170 million people worldwide.An infection by HCV causes high rates of chronic hepatitis(>75%)and progresses to liver cirrhosis and hepatocellular carcinoma ultimately.HCV can be eliminated by a combination of pegylatedα-interferon and the broad-spectrum antiviral drug ribavirin;however,this treatment is still associated with poor efficacy and tolerability and is often accompanied by serious side-effects.While some novel direct-actingantivirals against HCV have been developed recently,high medical costs limit the access to the therapy in cost-sensitive countries.To search for new natural anti-HCV agents,we screened local agricultural products for their suppressive activities against HCV replication using the HCV replicon cell system in vitro.We found a potent inhibitor of HCV RNA expression in the extracts of blueberry leaves and then identified oligomeric proanthocyanidin as the active ingredient.Further investigations into the action mechanism of oligomeric proanthocyanidin suggested that it is an inhibitor of heterogeneous nuclear ribonucleoproteins(hn RNPs)such as hn RNP A2/B1.In this review,we presented an overview of functional foods and ingredients efficient for HCV infection,the chemical structural characteristics of oligomeric proanthocyanidin,and its action mechanism.

  9. Physiological relevance of plant 2-Cys peroxiredoxin overoxidation level and oligomerization status.

    Science.gov (United States)

    Cerveau, Delphine; Ouahrani, Djelloul; Marok, Mohamed Amine; Blanchard, Laurence; Rey, Pascal

    2016-01-01

    Peroxiredoxins are ubiquitous thioredoxin-dependent peroxidases presumed to display, upon environmental constraints, a chaperone function resulting from a redox-dependent conformational switch. In this work, using biochemical and genetic approaches, we aimed to unravel the factors regulating the redox status and the conformation of the plastidial 2-Cys peroxiredoxin (2-Cys PRX) in plants. In Arabidopsis, we show that in optimal growth conditions, the overoxidation level mainly depends on the availability of thioredoxin-related electron donors, but not on sulfiredoxin, the enzyme reducing the 2-Cys PRX overoxidized form. We also observed that upon various physiological temperature, osmotic and light stress conditions, the overoxidation level and oligomerization status of 2-Cys PRX can moderately vary depending on the constraint type. Further, no major change was noticed regarding protein conformation in water-stressed Arabidopsis, barley and potato plants, whereas species-dependent up- and down-variations in overoxidation were observed. In contrast, both 2-Cys PRX overoxidation and oligomerization were strongly induced during a severe oxidative stress generated by methyl viologen. From these data, revealing that the oligomerization status of plant 2-Cys PRX does not exhibit important variation and is not tightly linked to the protein redox status upon physiologically relevant environmental constraints, the possible in planta functions of 2-Cys PRX are discussed.

  10. Structural reorganisation and potential toxicity of oligomeric species formed during the assembly of amyloid fibrils.

    Directory of Open Access Journals (Sweden)

    Mookyung Cheon

    2007-09-01

    Full Text Available Increasing evidence indicates that oligomeric protein assemblies may represent the molecular species responsible for cytotoxicity in a range of neurological disorders including Alzheimer and Parkinson diseases. We use all-atom computer simulations to reveal that the process of oligomerization can be divided into two steps. The first is characterised by a hydrophobic coalescence resulting in the formation of molten oligomers in which hydrophobic residues are sequestered away from the solvent. In the second step, the oligomers undergo a process of reorganisation driven by interchain hydrogen bonding interactions that induce the formation of beta sheet rich assemblies in which hydrophobic groups can become exposed. Our results show that the process of aggregation into either ordered or amorphous species is largely determined by a competition between the hydrophobicity of the amino acid sequence and the tendency of polypeptide chains to form arrays of hydrogen bonds. We discuss how the increase in solvent-exposed hydrophobic surface resulting from such a competition offers an explanation for recent observations concerning the cytotoxicity of oligomeric species formed prior to mature amyloid fibrils.

  11. Non-Enzymatic Oligomerization of 3’, 5’ Cyclic AMP

    Science.gov (United States)

    Costanzo, Giovanna; Pino, Samanta; Timperio, Anna Maria; Šponer, Judit E.; Šponer, Jiří; Nováková, Olga; Šedo, Ondrej; Zdráhal, Zbyněk; Di Mauro, Ernesto

    2016-01-01

    Recent studies illustrate that short oligonucleotide sequences can be easily produced from nucleotide precursors in a template-free non-enzymatic way under dehydrating conditions, i.e. using essentially dry materials. Here we report that 3’,5’ cyclic AMP may also serve as a substrate of the reaction, which proceeds under moderate conditions yet with a lower efficiency than the previously reported oligomerization of 3’,5’ cyclic GMP. Optimally the oligomerization requires (i) a temperature of 80°C, (ii) a neutral to alkaline environment and (iii) a time on the order of weeks. Differences in the yield and required reaction conditions of the oligomerizations utilizing 3’,5’ cGMP and cAMP are discussed in terms of the crystal structures of the compounds. Polymerization of 3’,5’ cyclic nucleotides, whose paramount relevance in a prebiotic chemistry context has been widely accepted for decades, supports the possibility that the origin of extant genetic materials might have followed a direct uninterrupted path since its very beginning, starting from non-elaborately pre-activated monomer compounds and simple reactions. PMID:27802310

  12. Gelatin-based biomaterial engineering with anhydride-containing oligomeric cross-linkers.

    Science.gov (United States)

    Loth, Tina; Hötzel, Rudi; Kascholke, Christian; Anderegg, Ulf; Schulz-Siegmund, Michaela; Hacker, Michael C

    2014-06-01

    Chemically cross-linked gelatin hydrogels are versatile cell-adhesive hydrogel materials that have been established for a variety of biomedical applications. The most prominent cross-linker is glutaraldehyde, which, however, has been described to cause compatibility problems and loss of microscopic but relevant structural features. A recently developed oligomeric cross-linker that contains anhydride functionalities was evaluated as cross-linker for the fabrication of gelatin-based hydrogels and microparticles. In a fast curing reaction, hydrogels composed of gelatin and oligomeric cross-linker were fabricated with good conversion over a wide concentration range of constituents and with cross-linkers of different anhydride contents. Hydrogel properties, such as dry weight and mechanics, could be controlled by hydrogel composition and rheological properties correlated to elastic moduli from 1 to 10 kPa. The gels were shown to be cytocompatible and promoted cell adhesion. In soft formulations, cells migrated into the hydrogel bulk. Gelatin microparticles prepared by a standard water-in-oil emulsion technique were also treated with the novel oligomers, and cross-linking degrees matching those obtained with glutaraldehyde were obtained. At the same time, fewer interparticular cross-links were observed. Fluorescein-derivatized cross-linkers yielded labeled microparticles in a concentration-dependent manner. The oligomeric cross-linkers are presented as an efficient and possibly more functional and compatible alternative to glutaraldehyde. The engineered hydrogel materials hold potential for various biomedical applications.

  13. Changes in dynamics upon oligomerization regulate substrate binding and allostery in amino acid kinase family members.

    Directory of Open Access Journals (Sweden)

    Enrique Marcos

    2011-09-01

    Full Text Available Oligomerization is a functional requirement for many proteins. The interfacial interactions and the overall packing geometry of the individual monomers are viewed as important determinants of the thermodynamic stability and allosteric regulation of oligomers. The present study focuses on the role of the interfacial interactions and overall contact topology in the dynamic features acquired in the oligomeric state. To this aim, the collective dynamics of enzymes belonging to the amino acid kinase family both in dimeric and hexameric forms are examined by means of an elastic network model, and the softest collective motions (i.e., lowest frequency or global modes of motions favored by the overall architecture are analyzed. Notably, the lowest-frequency modes accessible to the individual subunits in the absence of multimerization are conserved to a large extent in the oligomer, suggesting that the oligomer takes advantage of the intrinsic dynamics of the individual monomers. At the same time, oligomerization stiffens the interfacial regions of the monomers and confers new cooperative modes that exploit the rigid-body translational and rotational degrees of freedom of the intact monomers. The present study sheds light on the mechanism of cooperative inhibition of hexameric N-acetyl-L-glutamate kinase by arginine and on the allosteric regulation of UMP kinases. It also highlights the significance of the particular quaternary design in selectively determining the oligomer dynamics congruent with required ligand-binding and allosteric activities.

  14. Oligomerization of Clostridium perfringens epsilon toxin is dependent upon caveolins 1 and 2.

    Directory of Open Access Journals (Sweden)

    Christine M Fennessey

    Full Text Available Evidence from multiple studies suggests that Clostridium perfringens ε-toxin is a pore-forming toxin, assembling into oligomeric complexes in the plasma membrane of sensitive cells. In a previous study, we used gene-trap mutagenesis to identify mammalian factors contributing to toxin activity, including caveolin-2 (CAV2. In this study, we demonstrate the importance of caveolin-2 and its interaction partner, caveolin-1 (CAV1, in ε-toxin-induced cytotoxicity. Using CAV2-specific shRNA in a toxin-sensitive human kidney cell line, ACHN, we confirmed that cells deficient in CAV2 exhibit increased resistance to ε-toxin. Similarly, using CAV1-specific shRNA, we demonstrate that cells deficient in CAV1 also exhibit increased resistance to the toxin. Immunoprecipitation of CAV1 and CAV2 from ε-toxin-treated ACHN cells demonstrated interaction of both CAV1 and -2 with the toxin. Furthermore, blue-native PAGE indicated that the toxin and caveolins were components of a 670 kDa protein complex. Although ε-toxin binding was only slightly perturbed in caveolin-deficient cells, oligomerization of the toxin was dramatically reduced in both CAV1- and CAV2-deficient cells. These results indicate that CAV1 and -2 potentiate ε-toxin induced cytotoxicity by promoting toxin oligomerization - an event which is requisite for pore formation and, by extension, cell death.

  15. Phosphomimetic Mutations Enhance Oligomerization of Phospholemman and Modulate Its Interaction with the Na/K-ATPase*

    Science.gov (United States)

    Song, Qiujing; Pallikkuth, Sandeep; Bossuyt, Julie; Bers, Donald M.; Robia, Seth L.

    2011-01-01

    Na/K-ATPase (NKA) activity is dynamically regulated by an inhibitory interaction with a small transmembrane protein, phospholemman (PLM). Inhibition is relieved upon PLM phosphorylation. Phosphorylation may alter how PLM interacts with NKA and/or itself, but details of these interactions are unknown. To address this, we quantified FRET between PLM and its regulatory target NKA in live cells. Phosphorylation of PLM was mimicked by mutation S63E (PKC site), S68E (PKA/PKC site), or S63E/S68E. The dependence of FRET on protein expression in live cells yielded information about the structure and binding affinity of the PLM-NKA regulatory complex. PLM phosphomimetic mutations altered the quaternary structure of the regulatory complex and reduced the apparent affinity of the PLM-NKA interaction. The latter effect was likely due to increased oligomerization of PLM phosphomimetic mutants, as suggested by PLM-PLM FRET measurements. Distance constraints obtained by FRET suggest that phosphomimetic mutations slightly alter the oligomer quaternary conformation. Photon-counting histogram measurements revealed that the major PLM oligomeric species is a tetramer. We conclude that phosphorylation of PLM increases its oligomerization into tetramers, decreases its binding to NKA, and alters the structures of both the tetramer and NKA regulatory complex. PMID:21220422

  16. Disruption of oligomerization induces nucleocytoplasmic shuttling of leukemia-associated rho Guanine-nucleotide exchange factor.

    Science.gov (United States)

    Grabocka, Elda; Wedegaertner, Philip B

    2007-10-01

    The rgsRhoGEFs comprise a subfamily of three guanine nucleotide exchange factors, which function in linking heterotrimeric G-proteins to the monomeric RhoGTPase. Here, we reveal the novel finding that oligomerization of leukemia-associated RhoGEF (LARG) functions to prevent nucleocytoplasmic shuttling and to retain LARG in the cytoplasm. We establish that oligomerization is mediated by a predicted coiled-coil sequence (amino acids 1507-1520) in the extreme C terminus of LARG and that substitution of isoleucines 1507/1510 with alanines disrupts homo-oligomerization and leads to nucleocytoplasmic shuttling via the CRM1 nuclear transport pathway. In addition, we demonstrate that induced dimerization of an otherwise nuclear monomeric LARG mutant promotes cytoplasmic localization. Furthermore, we establish that nuclear import of monomeric LARG is mediated by the nuclear localization sequence (29)PTDKKQK(35) in the extreme N terminus. We propose that nucleocytoplasmic shuttling provides a mechanism for spatially regulating the activity of LARG toward its cytoplasmic targets and potentially new nuclear targets.

  17. Organization of the mitochondrial apoptotic BAK pore: oligomerization of the BAK homodimers.

    Science.gov (United States)

    Aluvila, Sreevidya; Mandal, Tirtha; Hustedt, Eric; Fajer, Peter; Choe, Jun Yong; Oh, Kyoung Joon

    2014-01-31

    The multidomain pro-apoptotic Bcl-2 family proteins BAK and BAX are believed to form large oligomeric pores in the mitochondrial outer membrane during apoptosis. Formation of these pores results in the release of apoptotic factors including cytochrome c from the intermembrane space into the cytoplasm, where they initiate the cascade of events that lead to cell death. Using the site-directed spin labeling method of electron paramagnetic resonance (EPR) spectroscopy, we have determined the conformational changes that occur in BAK when the protein targets to the membrane and forms pores. The data showed that helices α1 and α6 disengage from the rest of the domain, leaving helices α2-α5 as a folded unit. Helices α2-α5 were shown to form a dimeric structure, which is structurally homologous to the recently reported BAX "BH3-in-groove homodimer." Furthermore, the EPR data and a chemical cross-linking study demonstrated the existence of a hitherto unknown interface between BAK BH3-in-groove homodimers in the oligomeric BAK. This novel interface involves the C termini of α3 and α5 helices. The results provide further insights into the organization of the BAK oligomeric pores by the BAK homodimers during mitochondrial apoptosis, enabling the proposal of a BAK-induced lipidic pore with the topography of a "worm hole."

  18. Dealuminated ZSM-5 Zeolite Catalyst for Ethylene Oligomerization to Liquid Fuels

    Institute of Scientific and Technical Information of China (English)

    Nor Aishah Saidina Amin; Didi Dwi Anggoro

    2002-01-01

    Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronstedacid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidityof ZSM-5 zeolite, is an important step in the conversion of natural gas to liquid fuels. The framework Si/Alratio reflects the number of potential acid sites and the acid strength of the ZSM-5 catalyst. ZSM-5 withthe mole ratio SiO2/Al2O3 equal to 30 was dealuminated for different periods of time according to theacidic ion-exchange method to produce ZSM-5 with various Si/Al ratios. The FT-IR analysis revealedthat the integrated framework aluminum band, non-framework aluminum band, and silanol groups areasof the ZSM-5 zeolites decreased after being dealuminated. The performance of the dealuminated zeolitewas tested for ethylene oligomerization. The results demonstrated that the dealumination of ZSM-5 ledto higher ethylene conversion, but the gasoline selectivity was reduced compared to the performance of aZSM-5 zeolite. The characterization results revealed the amount of aluminum in the zeolitic framework,the crystallinity of the ZSM-5 zeolite, and the Si/Al ratio affected the formation of Bronsted acid sites.The number of the Bronsted acid sites on the catalyst active sites is important in the olefin conversion toliquid hydrocarbons.

  19. Play or science?

    DEFF Research Database (Denmark)

    Lieberoth, Andreas; Pedersen, Mads Kock; Sherson, Jacob

    2015-01-01

    Crowdscience games may hold unique potentials as learning opportunities compared to games made for fun or education. They are part of an actual science problem solving process: By playing, players help scientists, and thereby interact with real continuous research processes. This mixes the two...... worlds of play and science in new ways. During usability testing we discovered that users of the crowdscience game Quantum Dreams tended to answer questions in game terms, even when directed explicitly to give science explanations. We then examined these competing frames of understanding though a mixed...... correlational and grounded theory analysis. This essay presents the core ideas of crowdscience games as learning opportunities, and reports how a group of players used “game”, “science” and “conceptual” frames to interpret their experience. Our results suggest that oscillating between the frames instead...

  20. Understanding Games as Played

    DEFF Research Database (Denmark)

    Leino, Olli Tapio

    2009-01-01

    Researchers interested in player’s experience would assumedly, across disciplines, agree that the goal behind enquiries into player’s experience is to understand the how games’ features end up affecting the player’s experience. Much of the contemporary interdisciplinary research into player......’s experience leans toward the empirical-scientific, in the forms (neuro)psychology, sociology and cognitive science, to name a few. In such approaches, for example demonstrating correlation between physiological symptoms and an in-game event may amount to ‘understanding’. However, the experience of computer...... game play is a viable topic also for computer game studies within the general tradition of humanities. In such context, the idea of ‘understanding an experience’ invites an approach focusing on the experienced significance of events and objects within computer game play. This focus, in turn, suggests...

  1. Ravens at Play

    Directory of Open Access Journals (Sweden)

    Deborah Bird Rose

    2011-09-01

    Full Text Available ‘We were driving through Death Valley, an American-Australian and two Aussies, taking the scenic route from Las Vegas to Santa Cruz.’ This multi-voiced account of multispecies encounters along a highway takes up the challenge of playful and humorous writing that is as well deeply serious and theoretically provocative. Our travels brought us into what Donna Haraway calls the contact zone: a region of recognition and response. The contact zone is a place of significant questions: ‘Who are you, and so who are we? Here we are, and so what are we to become?’ Events were everything in this ecology of play, in which the movements of all the actors involved the material field in its entirety. We were brought into dances of approach and withdrawal, dances emerging directly, to paraphrase Brian Massumi, from the dynamic relation between a myriad of charged particles.

  2. Public Computation & Boundary Play

    CERN Document Server

    Sengupta, Pratim

    2016-01-01

    In this paper, we introduce 'public computation' as a genre of learning environments that can be used to radically broaden public participation in authentic, computation-enabled STEM disciplinary practices. Our paradigmatic approach utilizes open source software designed for professional scientists, engineers and digital artists, and situates them in an undiluted form, alongside live and archived expert support, in a public space. We present a case study of DigiPlay, a prototypical public computation space we designed at the University of Calgary, where users can interact directly with scientific simulations as well as the underlying open source code using an array of massive multi- touch screens. We argue that in such a space, public interactions with the code can be thought of as boundary work and play, through which public participation becomes legitimate scientific act, as the public engages in scientific creation through truly open-ended explorations with the code.

  3. Play. Learn. Innovate

    DEFF Research Database (Denmark)

    Sproedt, Henrik

    evidence that play and games could be interesting perspectives to take in order to understand complex social interaction. I come to the conclusion that – in innovation settings – the social dynamics that affect the process are essentially about transformation of knowledge across boundaries. I propose......„Play. Learn. Innovate. – Grasping the Social Dynamics of Participatory Innovation“ the title of this thesis describes how the complex interplay of unexpected events led to some burning questions and eventually to this thesis, which one could call an innovation*1*. During several years...... study were to better understand the theoretical foundations and practical implications of complex social interaction in organizational innovation settings. As I did not find any existing models or hypotheses that I was interested in testing I set out to discover how I could grasp complex social...

  4. "Playing" with our users

    DEFF Research Database (Denmark)

    Brooks, Anthony Lewis

    2014-01-01

    was from the amazing Dr Anthony Lewis Brooks (aka Tony) who has conceived the concepts GameAbilitation, ArtAbilitation, and Ludic Engagement Designs for All. While presenting some of his work on GameAbilitation and ArtAbilitation he brought up the subject of conducting research with users with disabilities......, about what happens to our users when research is over, funds are gone and the curtain of experiments has fallen. Dr Brooks presented the case of a young user who while unable to move and communicate had to part with the test device that provided him with interactive playful experience. We’ve all been...... confined in a house. For researchers that work with people with disabilities and in my case with playful interactions and positive immersive experience, we might have to think harder when we write project proposals or sketch our methodology. Devices, software and experience should be available to the users...

  5. Creativity and Playfulness

    DEFF Research Database (Denmark)

    Ejsing-Duun, Stine; Skovbjerg, Helle Marie

    2015-01-01

    Abstract: This article explores how student behavior and interactions change when teachers use “producing games” as a primary pedagogical strategy (Papert, 1980; Ejsing-Duun and Karoff, 2014). Based on student and teacher actions and responses, as well as on students' production—observed during f...... fieldwork—this paper emphasizes the importance of understanding how students explore creativity and playfulness while producing in learning situations....

  6. Creativity and Playfulness

    DEFF Research Database (Denmark)

    Ejsing-Duun, Stine; Skovbjerg, Helle Marie

    2015-01-01

    Abstract: This article explores how student behavior and interactions change when teachers use “producing games” as a primary pedagogical strategy (Papert, 1980; Ejsing-Duun and Karoff, 2014). Based on student and teacher actions and responses, as well as on students' production—observed during f...... fieldwork—this paper emphasizes the importance of understanding how students explore creativity and playfulness while producing in learning situations....

  7. Protein misfolding, congophilia, oligomerization, and defective amyloid processing in preeclampsia.

    Science.gov (United States)

    Buhimschi, Irina A; Nayeri, Unzila A; Zhao, Guomao; Shook, Lydia L; Pensalfini, Anna; Funai, Edmund F; Bernstein, Ira M; Glabe, Charles G; Buhimschi, Catalin S

    2014-07-16

    Preeclampsia is a pregnancy-specific disorder of unknown etiology and a leading contributor to maternal and perinatal morbidity and mortality worldwide. Because there is no cure other than delivery, preeclampsia is the leading cause of iatrogenic preterm birth. We show that preeclampsia shares pathophysiologic features with recognized protein misfolding disorders. These features include urine congophilia (affinity for the amyloidophilic dye Congo red), affinity for conformational state-dependent antibodies, and dysregulation of prototype proteolytic enzymes involved in amyloid precursor protein (APP) processing. Assessment of global protein misfolding load in pregnancy based on urine congophilia (Congo red dot test) carries diagnostic and prognostic potential for preeclampsia. We used conformational state-dependent antibodies to demonstrate the presence of generic supramolecular assemblies (prefibrillar oligomers and annular protofibrils), which vary in quantitative and qualitative representation with preeclampsia severity. In the first attempt to characterize the preeclampsia misfoldome, we report that the urine congophilic material includes proteoforms of ceruloplasmin, immunoglobulin free light chains, SERPINA1, albumin, interferon-inducible protein 6-16, and Alzheimer's β-amyloid. The human placenta abundantly expresses APP along with prototype APP-processing enzymes, of which the α-secretase ADAM10, the β-secretases BACE1 and BACE2, and the γ-secretase presenilin-1 were all up-regulated in preeclampsia. The presence of β-amyloid aggregates in placentas of women with preeclampsia and fetal growth restriction further supports the notion that this condition should join the growing list of protein conformational disorders. If these aggregates play a pathophysiologic role, our findings may lead to treatment for preeclampsia.

  8. Computational studies on receptor-ligand interactions between novel buffalo (Bubalus bubalis) nucleotide-binding oligomerization domain-containing protein 2 (NOD2) variants and muramyl dipeptide (MDP).

    Science.gov (United States)

    Brahma, Biswajit; Patra, Mahesh Chandra; Mishra, Purusottam; De, Bidhan Chandra; Kumar, Sushil; Maharana, Jitendra; Vats, Ashutosh; Ahlawat, Sonika; Datta, Tirtha Kumar; De, Sachinandan

    2016-04-01

    Nucleotide binding and oligomerization domain 2 (NOD2), a member of intracellular NOD-like receptors (NLRs) family, recognizes the bacterial peptidoglycan, muramyl dipeptide (MDP) and initiates host immune response. The precise ligand recognition mechanism of NOD2 has remained elusive, although studies have suggested leucine rich repeat (LRR) region of NOD2 as the possible binding site of MDP. In this study, we identified multiple transcripts of NOD2 gene in buffalo (buNOD2) and at least five LRR variants (buNOD2-LRRW (wild type), buNOD2-LRRV1-V4) were found to be expressed in buffalo peripheral blood mononuclear cells. The newly identified buNOD2 transcripts were shorter in lengths as a result of exon-skipping and frame-shift mutations. Among the variants, buNOD2-LRRW, V1, and V3 were expressed more frequently in the animals studied. A comparative receptor-ligand interaction study through modeling of variants, docking, and molecular dynamics simulation revealed that the binding affinity of buNOD2-LRRW towards MDP was greater than that of the shorter variants. The absence of a LRR segment in the buNOD2 variants had probably affected their affinity toward MDP. Notwithstanding a high homology among the variants, the amino acid residues that interact with MDP were located on different LRR motifs. The binding free energy calculation revealed that the amino acids Arg850(LRR4) and Glu932(LRR7) of buNOD2-LRRW, Lys810(LRR3) of buNOD2-LRRV1, and Lys830(LRR3) of buNOD2-LRRV3 largely contributed towards MDP recognition. The knowledge of MDP recognition and binding modes on buNOD2 variants could be useful to understand the regulation of NOD-mediated immune response as well as to develop next generation anti-inflammatory compounds.

  9. Celadon Figurines Play Instruments

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    This group of figurines, each 0.15m tall, were unearthed from a Tang Dynasty tomb in Changsha in 1977. Music was very developed in the Tang Dynasty. Colorful musical instruments and dances were popular both among the people and in the palace. These vivid-looking figurines wear pleated skirts with small sleeves and open chest, a style influenced by the non-Han nationalities living in the north and west of China. Some of the musical instruments were brought from the Western Regions. The figurines are playing the xiao (a vertical bamboo flute), the konghou (an

  10. Motivation, Creativity, Play & Learning

    DEFF Research Database (Denmark)

    Petersson, Eva

    2005-01-01

    implementation of robotic physical movement synchronously manipulated from sourced data movement information of a human. SoundScapes is a concept based on non-verbal communication and stimulation through interactive play with sounds and images, which is being realised in the production of a non-wearable sensor...... groups of children, including children with severe physical/multi disabilities. The sourced capture of the human data is from enhanced virtual interactive space created from sensors. The data is constituted of the situated multimodal communication and forms of expression. The ‘VIS’ is considered...

  11. Motivation, Creativity, Play & Learning

    DEFF Research Database (Denmark)

    Petersson, Eva

    2005-01-01

    implementation of robotic physical movement synchronously manipulated from sourced data movement information of a human. SoundScapes is a concept based on non-verbal communication and stimulation through interactive play with sounds and images, which is being realised in the production of a non-wearable sensor...... groups of children, including children with severe physical/multi disabilities. The sourced capture of the human data is from enhanced virtual interactive space created from sensors. The data is constituted of the situated multimodal communication and forms of expression. The ‘VIS’ is considered...

  12. "Playing" with our users

    DEFF Research Database (Denmark)

    Brooks, Anthony Lewis

    2014-01-01

    . Unfortunately if donated in the school they are rarely being used by the students. In the case of virtual reality or artistic installations it is extremely difficult to provide such equipment to users. Last but not least we are not sure how the software will be used and if the experience will continue...... after the conduct of the research. If not due to restrictions, user should at least continue to be part of the research’s debrief and next steps. While I was in Nottingham I realised that sometimes our research, our playful educational experience, our DIY VR helmet, our beta, glitchy, research-only game...

  13. Turning training into play

    DEFF Research Database (Denmark)

    Aarhus, Rikke; Grönvall, Erik; Larsen, Simon Bo;

    2011-01-01

    Embodied gaming has been adopted and gained credibility in the field of physical rehabilitation. In this paper, we report on findings from a six-month-long study of three groups of senior citizens, and their use of Nintendo Wii Fit in a supervised physical training context. We argue that the study...... participants generally found physical training both fun and socially engaging, and experienced improved fitness. We also argue that embodied gaming motivates seniors to do more than they think themselves capable of, and allows seniors with different mental and physical capabilities to play together. However...

  14. Play and playfulness, basic features of early childhood education

    NARCIS (Netherlands)

    Singer, E.

    2013-01-01

    This article argues that play and playfulness are basic features in early childhood education, but that play curricula can have serious drawbacks. The starting point is the play theory of the Dutch historian Johan Huizinga, a radical critic of the focus on the educational benefits of play. According

  15. Play and playfulness, basic features of early childhood education

    NARCIS (Netherlands)

    Singer, E.

    2013-01-01

    This article argues that play and playfulness are basic features in early childhood education, but that play curricula can have serious drawbacks. The starting point is the play theory of the Dutch historian Johan Huizinga, a radical critic of the focus on the educational benefits of play. According

  16. Playing The Lobby

    DEFF Research Database (Denmark)

    2014-01-01

    Playing a game can be defined as, in a fun way, to reach a goal by means of helpers and challenged by obstacles and opponents. In this workshop we will gain a new understanding of the lobby by making it into a game. The lobby of the museum can be understood as a game in which the players (the....... The object is surprisingly not to play the games, but to design them. Through the design process we are forced to discuss: What are the challenges of a particular lobby (e.g. ticketing, queueing, other visitors, guards, getting lost)? Which properties do the players have (e.g. patience, expectations, need...... of a toilet)? what boosters may they obtain in the lobby (e.g. coffee, help, souvenirs, signs)? And how can we make this an enjoyable experience? The object of the games is to understand the lobby in a new way to identify problems, and think of ways to improve the functions, flow, and services of the lobby....

  17. Playing it Real

    DEFF Research Database (Denmark)

    Grubert, Jens; Morrison, Ann; Munz, Helmut

    2012-01-01

    Magic lens and static peephole interfaces are used in numerous consumer mobile phone applications such as Augmented Reality browsers, games or digital map applications in a variety of contexts including public spaces. Interface performance has been evaluated for various interaction tasks involving...... spatial relationships in a scene. However, interface usage outside laboratory conditions has not been considered in depth in the evaluation of these interfaces. We present findings about the usage of magic lens and static peephole interfaces for playing a find-and-select game in a public space and report...... on the reactions of the public audience to participants’ interactions. Contrary to our expectations participants favored the magic lens over a static peephole interface despite tracking errors, fatigue and potentially conspicuous gestures. Most passersby did not pay attention to the participants and vice versa...

  18. Domain 2 of a Kazal serine proteinase inhibitor SPIPm2 from Penaeus monodon possesses antiviral activity against WSSV.

    Science.gov (United States)

    Visetnan, Suwattana; Donpudsa, Suchao; Supungul, Premruethai; Tassanakajon, Anchalee; Rimphanitchayakit, Vichien

    2014-12-01

    A 5-domain Kazal type serine proteinase inhibitor SPIPm2 from Penaeus monodon is involved in innate immune defense against white spot syndrome virus (WSSV). To test which domains were involved, the 5 domains of SPIPm2 were over-expressed and tested against WSSV infection. By using hemocyte primary cell culture treated with each recombinant SPIPm2 domain along with WSSV, the expression of WSSV early genes ie1, WSV477 and late gene VP28 were substantially reduced as compared to other domains when the recombinant domain 2, rSPIPm2D2, was used. Injecting the WSSV along with rSPIPm2D2 but not with other domains caused delay in mortality rate of the infected shrimp. The results indicate that the SPIPm2D2 possesses strong antiviral activity and, hence, contributes predominantly to the antiviral activity of SPIPm2.

  19. Playful Learning and Montessori Education

    National Research Council Canada - National Science Library

    Angeline S Lillard

    2013-01-01

      Although Montessori education is often considered a form of playful learning, Maria Montessori herself spoke negatively about a major component of playful learning-pretend play, or fantasy-for young children...

  20. There's plenty of gloom at the bottom: the many challenges of accurate quantitation in size-based oligomeric separations.

    Science.gov (United States)

    Striegel, André M

    2013-11-01

    There is a variety of small-molecule species (e.g., tackifiers, plasticizers, oligosaccharides) the size-based characterization of which is of considerable scientific and industrial importance. Likewise, quantitation of the amount of oligomers in a polymer sample is crucial for the import and export of substances into the USA and European Union (EU). While the characterization of ultra-high molar mass macromolecules by size-based separation techniques is generally considered a challenge, it is this author's contention that a greater challenge is encountered when trying to perform, for quantitation purposes, separations in and of the oligomeric region. The latter thesis is expounded herein, by detailing the various obstacles encountered en route to accurate, quantitative oligomeric separations by entropically dominated techniques such as size-exclusion chromatography, hydrodynamic chromatography, and asymmetric flow field-flow fractionation, as well as by methods which are, principally, enthalpically driven such as liquid adsorption and temperature gradient interaction chromatography. These obstacles include, among others, the diminished sensitivity of static light scattering (SLS) detection at low molar masses, the non-constancy of the response of SLS and of commonly employed concentration-sensitive detectors across the oligomeric region, and the loss of oligomers through the accumulation wall membrane in asymmetric flow field-flow fractionation. The battle is not lost, however, because, with some care and given a sufficient supply of sample, the quantitation of both individual oligomeric species and of the total oligomeric region is often possible.

  1. Hsp70 oligomerization is mediated by an interaction between the interdomain linker and the substrate-binding domain.

    Directory of Open Access Journals (Sweden)

    Francesco A Aprile

    Full Text Available Oligomerization in the heat shock protein (Hsp 70 family has been extensively documented both in vitro and in vivo, although the mechanism, the identity of the specific protein regions involved and the physiological relevance of this process are still unclear. We have studied the oligomeric properties of a series of human Hsp70 variants by means of nanoelectrospray ionization mass spectrometry, optical spectroscopy and quantitative size exclusion chromatography. Our results show that Hsp70 oligomerization takes place through a specific interaction between the interdomain linker of one molecule and the substrate-binding domain of a different molecule, generating dimers and higher-order oligomers. We have found that substrate binding shifts the oligomerization equilibrium towards the accumulation of functional monomeric protein, probably by sequestering the helical lid sub-domain needed to stabilize the chaperone: substrate complex. Taken together, these findings suggest a possible role of chaperone oligomerization as a mechanism for regulating the availability of the active monomeric form of the chaperone and for the control of substrate binding and release.

  2. Hsp70 Oligomerization Is Mediated by an Interaction between the Interdomain Linker and the Substrate-Binding Domain

    Science.gov (United States)

    Aprile, Francesco A.; Dhulesia, Anne; Stengel, Florian; Roodveldt, Cintia; Benesch, Justin L. P.; Tortora, Paolo; Robinson, Carol V.; Salvatella, Xavier; Dobson, Christopher M.; Cremades, Nunilo

    2013-01-01

    Oligomerization in the heat shock protein (Hsp) 70 family has been extensively documented both in vitro and in vivo, although the mechanism, the identity of the specific protein regions involved and the physiological relevance of this process are still unclear. We have studied the oligomeric properties of a series of human Hsp70 variants by means of nanoelectrospray ionization mass spectrometry, optical spectroscopy and quantitative size exclusion chromatography. Our results show that Hsp70 oligomerization takes place through a specific interaction between the interdomain linker of one molecule and the substrate-binding domain of a different molecule, generating dimers and higher-order oligomers. We have found that substrate binding shifts the oligomerization equilibrium towards the accumulation of functional monomeric protein, probably by sequestering the helical lid sub-domain needed to stabilize the chaperone: substrate complex. Taken together, these findings suggest a possible role of chaperone oligomerization as a mechanism for regulating the availability of the active monomeric form of the chaperone and for the control of substrate binding and release. PMID:23840795

  3. Comparative analyses of quaternary arrangements in homo-oligomeric proteins in superfamilies: Functional implications.

    Science.gov (United States)

    Sudha, Govindarajan; Srinivasan, Narayanaswamy

    2016-09-01

    A comprehensive analysis of the quaternary features of distantly related homo-oligomeric proteins is the focus of the current study. This study has been performed at the levels of quaternary state, symmetry, and quaternary structure. Quaternary state and quaternary structure refers to the number of subunits and spatial arrangements of subunits, respectively. Using a large dataset of available 3D structures of biologically relevant assemblies, we show that only 53% of the distantly related homo-oligomeric proteins have the same quaternary state. Considering these homologous homo-oligomers with the same quaternary state, conservation of quaternary structures is observed only in 38% of the pairs. In 36% of the pairs of distantly related homo-oligomers with different quaternary states the larger assembly in a pair shows high structural similarity with the entire quaternary structure of the related protein with lower quaternary state and it is referred as "Russian doll effect." The differences in quaternary state and structure have been suggested to contribute to the functional diversity. Detailed investigations show that even though the gross functions of many distantly related homo-oligomers are the same, finer level differences in molecular functions are manifested by differences in quaternary states and structures. Comparison of structures of biological assemblies in distantly and closely related homo-oligomeric proteins throughout the study differentiates the effects of sequence divergence on the quaternary structures and function. Knowledge inferred from this study can provide insights for improved protein structure classification and function prediction of homo-oligomers. Proteins 2016; 84:1190-1202. © 2016 Wiley Periodicals, Inc.

  4. Isolation and quantification of oligomeric and polymeric procyanidins in leaves and flowers of Hawthorn (Crataegus spp.).

    Science.gov (United States)

    Hellenbrand, N; Sendker, J; Lechtenberg, M; Petereit, F; Hensel, A

    2015-07-01

    Proanthocyanidins (PAs) constitute a class of polyphenols with flavan-3-ols as monomeric building blocks. These polyphenols are mostly quantified by colorimetric methods or by chromatographic determination of monomeric flavan-3-ols or low molecular oligomers as lead compounds. No reliable analytical methods are available for unambiguous identification of the homologues series of oligo- and polymeric PAs. For Hawthorn leaf and flower (Crataegi folium cum flore) from Crataegus spp. (Rosaceae) a protocol for preparative isolation of oligomeric and polymeric PAs from an acetone-water extract was developed, yielding procyanidin reference clusters with defined degree of polymerization (DP) from 2 to 10 besides a procyanidin-polymer. Identity and purity of these clusters were proven by HPLC, MS and in part NMR studies. For identification and quantification from Hawthorn an ICH-Q2 validated UHPLC method with fluorimetric detection and less than 10min runtime was developed. The method enabled quantification of procyanidin clusters with DP from 2 to 10 besides the polymer fraction. Batch analysis revealed procyanidin contents of about 20 to 45mg/g from a homologues series of oligomeric PAs and about 50% of polymer fraction. Monitoring of procyanidin distribution during seasonal growth of fresh plants of Crataegus monogyna showed more or less constant contents between 20 and 55mg/g dry weight of oligomeric procyanidins during the growing season in the different plant organs with strong accumulation in the flowers and fruits (55mg/g dry weight). From these data it can be speculated that procyanidins serve as part of the plants defense system in the reproductive organs of the plant. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. LDRD final report on new homogeneous and supported oligomerization catalysts (LDRD 42461).

    Energy Technology Data Exchange (ETDEWEB)

    Hascall, Anthony G.; Kemp, Richard Alan

    2004-11-01

    The overall purpose of this LDRD is multifold. First, we are interested in preparing new homogeneous catalysts that can be used in the oligomerization of ethylene and in understanding commercially important systems better. Second, we are interested in attempting to support these new homogeneous catalysts in the pores of nano- or mesoporous materials in order to force new and unusual distributions of a-olefins to be formed during the oligomerization. Thus the overall purpose is to try to prepare new catalytic species and to possibly control the active site architecture in order to yield certain desired products during a catalytic reaction, much like nature does with enzymes. In order to rationally synthesize catalysts it is imperative to comprehend the function of the various components of the catalyst. In heterogeneous systems, it is of utmost importance to know how a support interacts with the active site of the catalyst. In fact, in the catalysis world this lack of fundamental understanding of the relationship between active site and support is the single largest reason catalysis is considered an 'empirical' or 'black box' science rather than a well-understood one. In this work we will be preparing novel ethylene oligomerization catalysts, which are normally P-O chelated homogeneous complexes, with new ligands that replace P with a stable carbene. We will also examine a commercially catalyst system and investigate the active site in it via X-ray crystallography. We will also attempt to support these materials inside the pores of nano- and mesoporous materials. Essentially, we will be tailoring the size and scale of the catalyst active site and its surrounding environment to match the size of the molecular product(s) we wish to make. The overall purpose of the study will be to prepare new homogeneous catalysts, and if successful in supporting them to examine the effects that steric constraints and pore structures can have on growing oligomer

  6. The effects of oligomerization on Saccharomyces cerevisiae Mcm4/6/7 function

    Directory of Open Access Journals (Sweden)

    Davey Megan J

    2010-09-01

    Full Text Available Abstract Background Minichromosome maintenance proteins (Mcm 2, 3, 4, 5, 6 and 7 are related by sequence and form a variety of complexes that unwind DNA, including Mcm4/6/7. A Mcm4/6/7 trimer forms one half of the Mcm2-7 hexameric ring and can be thought of as the catalytic core of Mcm2-7, the replicative helicase in eukaryotic cells. Oligomeric analysis of Mcm4/6/7 suggests that it forms a hexamer containing two Mcm4/6/7 trimers, however, under certain conditions trimeric Mcm4/6/7 has also been observed. The functional significance of the different Mcm4/6/7 oligomeric states has not been assessed. The results of such an assessment would have implications for studies of both Mcm4/6/7 and Mcm2-7. Results Here, we show that Saccharomyces cerevisiae Mcm4/6/7 reconstituted from individual subunits exists in an equilibrium of oligomeric forms in which smaller oligomers predominate in the absence of ATP. In addition, we found that ATP, which is required for Mcm4/6/7 activity, shifts the equilibrium towards larger oligomers, likely hexamers of Mcm4/6/7. ATPγS and to a lesser extent ADP also shift the equilibrium towards hexamers. Study of Mcm4/6/7 complexes containing mutations that interfere with the formation of inter-subunit ATP sites (arginine finger mutants indicates that full activity of Mcm4/6/7 requires all of its ATP sites, which are formed in a hexamer and not a trimer. In keeping with this observation, Mcm4/6/7 binds DNA as a hexamer. Conclusions The minimal functional unit of Mcm4/6/7 is a hexamer. One of the roles of ATP binding by Mcm4/6/7 may be to stabilize formation of hexamers.

  7. Structural properties of cyanase. Denaturation, renaturation, and role of sulfhydryls and oligomeric structure in catalytic activity.

    Science.gov (United States)

    Little, R M; Anderson, P M

    1987-07-25

    Cyanase is an inducible enzyme in Escherichia coli that catalyzes bicarbonate-dependent decomposition of cyanate to give ammonia and bicarbonate. The enzyme is composed of 8-10 identical subunits (Mr = 17,008). The objective of this study was to clarify some of the structural properties of cyanase for the purpose of understanding the relationship between oligomeric structure and catalytic activity. Circular dichroism studies showed that cyanase has a significant amount of alpha-helix and beta-sheet structure. The one sulfhydryl group per subunit does not react with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) unless cyanase is denatured. Denaturation is apparently complete in 10 M urea or 6 M guanidine hydrochloride, but is significantly reduced in 10 M urea by the presence of azide (analog of cyanate) and is incomplete in 8 M urea. Denatured cyanase could be renatured and reactivated (greater than 85%) by removal of denaturants. Reactivation was greatly facilitated by the presence of certain anions, particularly bicarbonate, and by high ionic strength and protein concentration. The catalytic activity of renatured cyanase was associated only with oligomer. Cyanase that had been denatured in the presence of DTNB to give a cyanase-DTNB derivative could also be renatured at 26 degrees C to give active cyanase-DTNB oligomer. The active oligomeric form of the cyanase-DTNB derivative could be converted reversibly to inactive dimer by lowering the temperature to 4 degrees C or by reduction of the ionic strength and removal of monoanions. These results provide evidence that free sulfhydryl groups are not required for catalytic activity and that catalytic activity may be dependent upon oligomeric structure.

  8. Mapping the conformational dynamics and pathways of spontaneous steric zipper Peptide oligomerization.

    Directory of Open Access Journals (Sweden)

    Dirk Matthes

    Full Text Available The process of protein misfolding and self-assembly into various, polymorphic aggregates is associated with a number of important neurodegenerative diseases. Only recently, crystal structures of several short peptides have provided detailed structural insights into -sheet rich aggregates, known as amyloid fibrils. Knowledge about early events of the formation and interconversion of small oligomeric states, an inevitable step in the cascade of peptide self-assembly, however, remains still limited. We employ molecular dynamics simulations in explicit solvent to study the spontaneous aggregation process of steric zipper peptide segments from the tau protein and insulin in atomistic detail. Starting from separated chains with random conformations, we find a rapid formation of structurally heterogeneous, -sheet rich oligomers, emerging from multiple bimolecular association steps and diverse assembly pathways. Furthermore, our study provides evidence that aggregate intermediates as small as dimers can be kinetically trapped and thus affect the structural evolution of larger oligomers. Alternative aggregate structures are found for both peptide sequences in the different independent simulations, some of which feature characteristics of the known steric zipper conformation (e.g., -sheet bilayers with a dry interface. The final aggregates interconvert with topologically distinct oligomeric states exclusively via internal rearrangements. The peptide oligomerization was analyzed through the perspective of a minimal oligomer, i.e., the dimer. Thereby all observed multimeric aggregates can be consistently mapped onto a space of reduced dimensionality. This novel method of conformational mapping reveals heterogeneous association and reorganization dynamics that are governed by the characteristics of peptide sequence and oligomer size.

  9. Oligomerization of Mannan-binding Lectin Dictates Binding Properties and Complement Activation.

    Science.gov (United States)

    Kjaer, T R; Jensen, L; Hansen, A; Dani, R; Jensenius, J C; Dobó, J; Gál, P; Thiel, S

    2016-07-01

    The complement system is a part of the innate immune system and is involved in recognition and clearance of pathogens and altered-self structures. The lectin pathway of the complement system is initiated when soluble pattern recognition molecules (PRMs) with collagen-like regions bind to foreign or altered self-surfaces. Associated with the collagen-like stems of these PRMs are three mannan-binding lectin (MBL)-associated serine proteases (MASPs) and two MBL-associated proteins (MAps). The most studied of the PRMs, MBL, is present in serum mainly as trimeric and tetrameric oligomers of the structural subunit. We hypothesized that oligomerization of MBL may influence both the potential to bind to micro organisms and the interaction with the MASPs and MAps, thus influencing the ability to initiate complement activation. When testing binding at 37 °C, we found higher binding of tetrameric MBL to Staphylococcus aureus (S. aureus) than trimeric and dimeric MBL. In serum, we found that tetrameric MBL was the main oligomeric form present in complexes with the MASPs and MAp44. Such preference was confirmed using purified forms of recombinant MBL (rMBL) oligomers, where tetrameric rMBL interacted stronger with all of the MASPs and MAp44, compared to trimeric MBL. As a direct consequence of the weaker interaction with the MASPs, we found that trimeric rMBL was inferior to tetrameric rMBL in activating the complement system. Our data suggest that the oligomeric state of MBL is crucial both for the binding properties and the effector function of MBL.

  10. APOBEC3G oligomerization is associated with the inhibition of both Alu and LINE-1 retrotransposition.

    Directory of Open Access Journals (Sweden)

    Takayoshi Koyama

    Full Text Available Alu and LINE-1 (L1, which constitute ~11% and ~17% of the human genome, respectively, are transposable non-LTR retroelements. They transpose not only in germ cells but also in somatic cells, occasionally causing cancer. We have previously demonstrated that antiretroviral restriction factors, human APOBEC3 (hA3 proteins (A-H, differentially inhibit L1 retrotransposition. In this present study, we found that hA3 members also restrict Alu retrotransposition at differential levels that correlate with those observed previously for L1 inhibition. Through deletion analyses based on the best-characterized hA3 member human APOBEC3G (hA3G, its N-terminal 30 amino acids were required for its inhibitory activity against Alu retrotransposition. The inhibitory effect of hA3G on Alu retrotransposition was associated with its oligomerization that was affected by the deletion of its N-terminal 30 amino acids. Through structural modeling, the amino acids 24 to 28 of hA3G were predicted to be located at the interface of the dimer. The mutation of these residues resulted in abrogated hA3G oligomerization, and consistently abolished the inhibitory activity of hA3G against Alu retrotransposition. Importantly, the anti-L1 activity of hA3G was also associated with hA3G oligomerization. These results suggest that the inhibitory activities of hA3G against Alu and L1 retrotransposition might involve a common mechanism.

  11. Modulation of the oligomerization of myelin proteolipid protein by transmembrane helix interaction motifs.

    Science.gov (United States)

    Ng, Derek P; Deber, Charles M

    2010-08-17

    Proteolipid protein (PLP) is a highly hydrophobic 276-residue integral membrane protein that constitutes more than 50% of the total protein in central nervous system myelin. Previous studies have shown that this protein exists in myelin as an oligomer rather than as a monomer, and mutations in PLP that lead to neurological disorders such as Pelizaeus-Merzbacher disease and spastic paraplegia type 2 have been reported to affect its normal oligomerization. Here we employ peptide-based and in vivo approaches to examine the role of the TM domain in the formation of PLP quaternary structure through homo-oligomeric helix-helix interactions. Focusing on the TM4 alpha-helix (sequence (239)FIAAFVGAAATLVSLLTFMIAATY(262)), the site of several disease-causing point mutations that involve putative small residue helix-helix interaction motifs in the TM4 sequence, we used SDS-PAGE, fluorescence resonance energy transfer, size-exclusion chromatography, and TOXCAT assays in an Escherichia coli membrane to show that the PLP TM4 helix readily assembles into varying oligomeric states. In addition, through targeted studies of the PLP TM4 alpha-helix with point mutations that selectively eliminate these small residue motifs via substitution of Gly, Ala, or Ser residues with Ile residues, we describe a potential mechanism through which disease-causing point mutations can lead to aberrant PLP assembly. The overall results suggest that TM segments in misfolded PLP monomers that expose and/or create surface-exposed helix-helix interaction sites that are normally masked may have consequences for disease.

  12. Oligomeric structure of a cathelicidin antimicrobial peptide in dodecylphosphocholine micelle determined by NMR spectroscopy.

    Science.gov (United States)

    Saravanan, Rathi; Bhattacharjya, Surajit

    2011-01-01

    The broad spectrum of antibacterial activities of host defense cationic antimicrobial peptides (AMPs) arises from their ability to perturb membrane integrity of the microbes. The mechanisms are often thought to require assembly of AMPs on the membrane surface to form pores. However, three dimensional structures in the oligomeric form of AMPs in the context of lipid membranes are largely limited. Here, we demonstrate that a 22-residue antimicrobial peptide, termed VK22, derived from fowlicidin-1, a cathelicidin family of AMP from chicken oligomerizes into a predominantly tetrameric state in zwitterionic dodecylphosphocholine (DPC) micelles. An ensemble of NMR structures of VK22 determined in 200mM perdeuterated DPC, from 755 NOE constrains including 19 inter-helical NOEs, had revealed an assembly of four helices arranged in anti-parallel fashion. Hydrogen bonds, C(α)H-O=C types, and van der Waals interactions among the helical sub-units appear to be involved in the stabilization of the quaternary structures. The central region of the barrel shaped tetrameric bundle is non-polar with clusters of aromatic residues, whereas all the cationic residues are positioned at the termini. Paramagnetic spin labeled NMR experiments indicated that the tetrameric structure is embedded into micelles such that the non-polar region located inside the lipid acyl chains. Structure and micelle localization of a monomeric version, obtained from substitution of two Tyr residues with Ala, of the peptide is also compared. The mutated peptide VK22AA has been found be localized at the surface of the micelles. The tetrameric structure of VK22 delineates a small water pore that can be larger in the higher order oligomers. As these results provide structural insights, at atomic resolution, into the oligomeric states of a helical AMP in lipid environment, the structural details may be further utilized for the design of novel self-assembled membrane protein mimics.

  13. Crystal structures from the Plasmodium peroxiredoxins: new insights into oligomerization and product binding

    Directory of Open Access Journals (Sweden)

    Qiu Wei

    2012-03-01

    Full Text Available Abstract Background Plasmodium falciparum is the protozoan parasite primarily responsible for more than one million malarial deaths, annually, and is developing resistance to current therapies. Throughout its lifespan, the parasite is subjected to oxidative attack, so Plasmodium antioxidant defences are essential for its survival and are targets for disease control. Results To further understand the molecular aspects of the Plasmodium redox system, we solved 4 structures of Plasmodium peroxiredoxins (Prx. Our study has confirmed PvTrx-Px1 to be a hydrogen peroxide (H2O2-sensitive peroxiredoxin. We have identified and characterized the novel toroid octameric oligomer of PyTrx-Px1, which may be attributed to the interplay of several factors including: (1 the orientation of the conserved surface/buried arginine of the NNLA(I/LGRS-loop; and (2 the C-terminal tail positioning (also associated with the aforementioned conserved loop which facilitates the intermolecular hydrogen bond between dimers (in an A-C fashion. In addition, a notable feature of the disulfide bonds in some of the Prx crystal structures is discussed. Finally, insight into the latter stages of the peroxiredoxin reaction coordinate is gained. Our structure of PyPrx6 is not only in the sulfinic acid (RSO2H form, but it is also with glycerol bound in a way (not previously observed indicative of product binding. Conclusions The structural characterization of Plasmodium peroxiredoxins provided herein provides insight into their oligomerization and product binding which may facilitate the targeting of these antioxidant defences. Although the structural basis for the octameric oligomerization is further understood, the results yield more questions about the biological implications of the peroxiredoxin oligomerization, as multiple toroid configurations are now known. The crystal structure depicting the product bound active site gives insight into the overoxidation of the active site and

  14. Imagination, Playfulness, and Creativity in Children's Play with Different Toys

    Science.gov (United States)

    Mo????ller, Signe?? Juhl?

    2015-01-01

    Based on a four-month experimental study of preschool children's play with creative-construction and social-fantasy toys, the author examines the in?uence of both types of toys on the play of preschool children. Her comparative analysis considers the impact of transformative play on the development of imagination during play activities and…

  15. Influence of point mutations on the stability, dimerization and oligomerization of human cystatin C and its L68Q variant

    Directory of Open Access Journals (Sweden)

    Aneta eSzymanska

    2012-07-01

    Full Text Available Human cystatin C (hCC is a small but very intriguing protein. Produced by all nucleated cells is found in almost all tissues and body fluids where, at physiological conditions, plays a role of a very potent inhibitor of cysteine proteases. Biologically active hCC is a monomeric protein but during cellular trafficking it forms dimers, transiently loosing its inhibitory activity. In vitro, dimerization of cystatin C was observed for the mature protein during crystallization trials, revealing that the mechanism of this process is based on the three dimensional swapping of the protein domains. In our work we have focused on the impact of two proposed hot spots in cystatin C structure on its conformational stability. Encouraged by promising results of the theoretical calculations, we designed and produced several hCC hinge region point mutation variants that display a variety of conformational stability and propensity for dimerization and aggregation. A similar approach, i.e. rational mutagenesis, has been also applied to study the amyloidogenic L68Q variant to determine the contribution of hydrophobic interactions and steric effect on the stability of monomeric cystatin C. In this overview we would like to summarize the results of our studies. The impact of a particular mutation on the properties of the studied proteins will be presented in the context of their thermal and mechanical stability, in vitro dimerization tendency as well as the outcome of crystallization. Better understanding of the mechanism and, especially, factors affecting conformational stability of cystatin C and access to stable monomeric and dimeric versions of the protein opens new perspectives in explaining the role of dimers and the domain swapping process in hCC oligomerization, as well as designing potential inhibitors of this process.

  16. Isolation and identification of oligomeric procyanidins from Crataegus leaves and flowers.

    Science.gov (United States)

    Svedström, Ulla; Vuorela, Heikki; Kostiainen, Risto; Tuominen, Jari; Kokkonen, Juha; Rauha, Jussi-Pekka; Laakso, Into; Hiltunen, Raimo

    2002-08-01

    Oligomeric procyanidins were isolated from the leaves and flowers of hawthorn (Crataegus laevigata). A trimer, epicatechin-(4 beta-->8)-epicatechin-(4 beta-->6)-epicatechin, and a pentamer consisting of (-)-epicatechin units linked through C-4 beta/C-8 bonds have been isolated from hawthorn for the first time, in addition to known procyanidins including dimers B-2, B-4 and B-5, trimers C-1 and epicatechin-(4 beta-->6)-epicatechin-(4 beta-->8)-epicatechin, and tetramer D-1. A fraction containing a hexamer was also found.

  17. Thermo-mechanical characterization of a monochlorophenyl, hepta isobutyl polyhedral oligomeric silsesquioxane/polystyrene composite

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, Ignazio, E-mail: iblanco@dii.unict.it; Bottino, Francesco A., E-mail: iblanco@dii.unict.it; Cicala, Gianluca, E-mail: iblanco@dii.unict.it; Cozzo, Giulia, E-mail: iblanco@dii.unict.it; Latteri, Alberta, E-mail: iblanco@dii.unict.it; Recca, Antonino, E-mail: iblanco@dii.unict.it [Department of Industrial Engineering, University of Catania, Viale A. Doria 6, 95125 Catania (Italy)

    2014-05-15

    The thermal and mechanical properties of a monochlorophenyl, hepta isobutyl Polyhedral Oligomeric Silsesquioxane/Polystyrene (ph,hib-POSS/PS) composite were studied and compared with those of pristine polymer. ph,hib-POSS/PS system was prepared by solubilization and precipitation of Polystyrene (PS) in the presence of POSS. Scanning Electron Microscopy (SEM) was performed to check the distribution of the filler in the polymer matrix. Dynamic Mechanical Analysis (DMA) was carried out to measure viscoelastic properties of solid samples. Degradations were carried out into a thermobalance and the obtained thermogravimetric (TG) and differential thermogravimetric (DTG) curves were discussed and interpreted.

  18. Esters of oligo-(glycerol carbonate-glycerol): New biobased oligomeric surfactants.

    Science.gov (United States)

    Holmiere, Sébastien; Valentin, Romain; Maréchal, Philippe; Mouloungui, Zéphirin

    2017-02-01

    Glycerol carbonate is one of the most potentially multifunction glycerol-derived compounds. Glycerol is an important by-product of the oleochemical industry. The oligomerization of glycerol carbonate, assisted by the glycerol, results in the production of polyhydroxylated oligomers rich in linear carbonate groups. The polar moieties of these oligomers (Mwesters of sorbitan polyethoxylates. The self-assembling properties of oligocarbonate esters were highlighted by their ability to stabilize inverse and multiple emulsions. The oligo-(glycerol carbonate-glycerol ether) with relatively low molecular weights showed properties of relatively high-molecular weight molecules, and constitute a viable "green" alternative to ethoxylated surfactants. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. [Theory of V.A. dogiel on polymerization and oligomerization as a general integration concept].

    Science.gov (United States)

    Makmaev, Iu V

    2010-01-01

    The theory of V.A. Dogiel on the significance of polymerization and ligomerization processes in the evolution of Protozoa and Metazoa is compared with the paper of I.I. Schmalhauisen (1972) on factors and steps of aromorph evolution. Dogiel's theory is considered as a general integration conception. Four steps are distinguished in the evolution of biological systems: (1) formation of morphofunctional system by units of the lower structural level, (2) polymerization of morphofunctional units of a system, (3) oligomerization of morphofunctional units of system by means of their reduction, uniting, or differentiation, (4) integration and stabilization of a system owing to development of morphofunctional connections between its parts.

  20. Thermo-mechanical characterization of a monochlorophenyl, hepta isobutyl polyhedral oligomeric silsesquioxane/polystyrene composite

    Science.gov (United States)

    Blanco, Ignazio; Bottino, Francesco A.; Cicala, Gianluca; Cozzo, Giulia; Latteri, Alberta; Recca, Antonino

    2014-05-01

    The thermal and mechanical properties of a monochlorophenyl, hepta isobutyl Polyhedral Oligomeric Silsesquioxane/Polystyrene (ph,hib-POSS/PS) composite were studied and compared with those of pristine polymer. ph,hib-POSS/PS system was prepared by solubilization and precipitation of Polystyrene (PS) in the presence of POSS. Scanning Electron Microscopy (SEM) was performed to check the distribution of the filler in the polymer matrix. Dynamic Mechanical Analysis (DMA) was carried out to measure viscoelastic properties of solid samples. Degradations were carried out into a thermobalance and the obtained thermogravimetric (TG) and differential thermogravimetric (DTG) curves were discussed and interpreted.

  1. Blue Light-excited Light-Oxygen-Voltage-sensing Domain 2 (LOV2) Triggers a Rearrangement of the Kinase Domain to Induce Phosphorylation Activity in Arabidopsis Phototropin1.

    Science.gov (United States)

    Oide, Mao; Okajima, Koji; Kashojiya, Sachiko; Takayama, Yuki; Oroguchi, Tomotaka; Hikima, Takaaki; Yamamoto, Masaki; Nakasako, Masayoshi

    2016-09-16

    Phototropin1 is a blue light (BL) receptor in plants and shows BL-dependent kinase activation. The BL-excited light-oxygen-voltage-sensing domain 2 (LOV2) is primarily responsible for the activation of the kinase domain; however, the molecular mechanism by which conformational changes in LOV2 are transmitted to the kinase domain remains unclear. Here, we investigated BL-induced structural changes of a minimum functional fragment of Arabidopsis phototropin1 composed of LOV2, the kinase domain, and a linker connecting the two domains using small-angle x-ray scattering (SAXS). The fragment existed as a dimer and displayed photoreversible SAXS changes reflected in the radii of gyration of 42.9 Å in the dark and 48.8 Å under BL irradiation. In the dark, the molecular shape reconstructed from the SAXS profiles appeared as two bean-shaped lobes in a twisted arrangement that was 170 Å long, 80 Å wide, and 50 Å thick. The molecular shape under BL became slightly elongated from that in the dark. By fitting the crystal structure of the LOV2 dimer and a homology model of the kinase domain to their inferred shapes, the BL-dependent change could be interpreted as the positional shift in the kinase domain relative to that of the LOV2 dimer. In addition, we found that lysine 475, a functionally important residue, in the N-terminal region of LOV2 plays a critical role in transmitting the structural changes in LOV2 to the kinase domain. The interface between the domains is critical for signaling, suitably changing the structure to activate the kinase in response to conformational changes in the adjoining LOV2.

  2. Crl binds to domain 2 of σ(S) and confers a competitive advantage on a natural rpoS mutant of Salmonella enterica serovar Typhi.

    Science.gov (United States)

    Monteil, Véronique; Kolb, Annie; Mayer, Claudine; Hoos, Sylviane; England, Patrick; Norel, Françoise

    2010-12-01

    The RpoS sigma factor (σ(S)) is the master regulator of the bacterial response to a variety of stresses. Mutants in rpoS arise in bacterial populations in the absence of stress, probably as a consequence of a subtle balance between self-preservation and nutritional competence. We characterized here one natural rpoS mutant of Salmonella enterica serovar Typhi (Ty19). We show that the rpoS allele of Ty19 (rpoS(Ty19)) led to the synthesis of a σ(S)(Ty19) protein carrying a single glycine-to-valine substitution at position 282 in σ(S) domain 4, which was much more dependent than the wild-type σ(S) protein on activation by Crl, a chaperone-like protein that increases the affinity of σ(S) for the RNA polymerase core enzyme (E). We used the bacterial adenylate cyclase two-hybrid system to demonstrate that Crl bound to residues 72 to 167 of σ(S) domain 2 and that G282V substitution did not directly affect Crl binding. However, this substitution drastically reduced the ability of σ(S)(Ty19) to bind E in a surface plasmon resonance assay, a defect partially rescued by Crl. The modeled structure of the Eσ(S) holoenzyme suggested that substitution G282V could directly disrupt a favorable interaction between σ(S) and E. The rpoS(Ty19) allele conferred a competitive fitness when the bacterial population was wild type for crl but was outcompeted in Δcrl populations. Thus, these results indicate that the competitive advantage of the rpoS(Ty19) mutant is dependent on Crl and suggest that crl plays a role in the appearance of rpoS mutants in bacterial populations.

  3. Disassembly intermediates of RbsD protein remain oligomeric despite the loss of an intact secondary structure

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Many proteins exist as homo-oligomers in living organisms wherein the change of oligomeric status apparently serves as an effective means for modulating their biological activities. We have previously reported that the homo-decameric RbsD from Escherichia coli undergoes stepwise disassembly and non-stepwise reassembly. Here the structural status of the urea-induced RbsD disassembly intermediates was examined, mainly using urea-containing polyacrylamide gel electrophoresis and chemical cross-linking. Such intermediates were found to remain oligomeric while losing their intact secondary structures. Such disassembly intermediates were able to effectively refold when the concentration of the urea denaturant was reduced to a lower level, or to refold/reassemble into the native decamers when urea was completely removed, as detected by non-denaturing polyacrylamide gel electrophoresis. These novel observations strongly suggest that the assembly of oligomeric proteins may occur before the completion of subunit folding.

  4. Structures and formation mechanisms of aquo/hydroxo oligomeric beryllium in aqueous solution: a density functional theory study.

    Science.gov (United States)

    Jin, Xiaoyan; Liao, Rongbao; Wu, Hai; Huang, Zhengjie; Zhang, Hong

    2015-09-01

    The structures and formation mechanisms of a wide variety of aquo/hydroxo oligomeric beryllium clusters were investigated using density functional theory. The structural parameters of beryllium clusters were found to vary regularly with the stepwise substitution of bound water molecules in the inner coordination sphere by hydroxyl groups. According to the Gibbs free energies deduced from SMD solvation model computations, unhydrolyzed oligomeric beryllium species are the most favorable products of polymerization, independent of the degrees of hydrolysis of the reactants. Simulation of the formation processes of oligomeric beryllium showed that polymerization, in essence, involves the nucleophilic attack of a terminal hydroxyl group in one BeO4 tetrahedron on the beryllium center in another BeO4 tetrahedron, leading to the bridging of two BeO4 tetrahedrons by a hydroxyl group.

  5. Playful Learning and Montessori Education

    Science.gov (United States)

    Lillard, Angeline S.

    2013-01-01

    Although Montessori education is often considered a form of playful learning, Maria Montessori herself spoke negatively about a major component of playful learning--pretend play, or fantasy--for young children. In this essay, the author discusses this apparent contradiction: how and why Montessori education includes elements of playful learning…

  6. Play and Positive Group Dynamics

    Science.gov (United States)

    Thompson, Pam; White, Samantha

    2010-01-01

    Play is an important part of a child's life and essential to learning and development (Vygotsky, 1978). It is vital that students participate in play and that play be conducted in a restorative manner. Play allows a variety of group dynamics to emerge. Irvin Yalom (1995) identifies 11 curative factors of the group experience. These factors include…

  7. Play and playfulness in early childhood education and care.

    Directory of Open Access Journals (Sweden)

    Singer E.

    2015-06-01

    Full Text Available Play and playfulness are basic features in early childhood education. The elements of play are pleasure, a sense of freedom, and the co-construction of shared meaning through the use of rules or rhythms. Play and learning are closely related in early childhood. But when the focus on the educational benefits of play becomes too strong, the most essential feature of play is lost: children’s pleasure. Young children in group settings often have to adapt to the teachers’ demands related to security, hygiene, and social norms and values. But the playfulness of the teachers helps to overcome differences in power in the caregiver-child relationship and prevents young children from becoming overburdened with strict rules and group discipline. Play and playfulness are a resource of shared pleasure and creativity in learning processes.

  8. Ouroboros - Playing A Biochemical

    Directory of Open Access Journals (Sweden)

    D. T. Rodrigues

    2014-08-01

    Full Text Available Ouroboros: Playing A Biochemical RODRIGUES,D.T.1,2;GAYER, M.C.1,2; ESCOTO, D.F.1; DENARDIN, E.L.G.2, ROEHRS, R.1,2 1Interdisciplinary Research Group on Teaching Practice, Graduate Program in Biochemistry, Unipampa, RS, Brazil 2Laboratory of Physicochemical Studies and Natural Products, Post Graduate Program in Biochemistry, Unipampa, RS, Brazil Introduction: Currently, teachers seek different alternatives to enhance the teaching-learning process. Innovative teaching methodologies are increasingly common tools in educational routine. The use of games, electronic or conventional, is an effective tool to assist in learning and also to raise the social interaction between students. Objective: In this sense our work aims to evaluate the card game and "Ouroboros" board as a teaching and learning tool in biochemistry for a graduating class in Natural Sciences. Materials and methods: The class gathered 22 students of BSc in Natural Sciences. Each letter contained a question across the board that was drawn to a group to answer within the allotted time. The questions related concepts of metabolism, organic and inorganic chemical reactions, bioenergetics, etc.. Before the game application, students underwent a pre-test with four issues involving the content that was being developed. Soon after, the game was applied. Then again questions were asked. Data analysis was performed from the ratio of the number of correct pre-test and post-test answers. Results and discussion: In the pre-test 18.1% of the students knew all issues, 18.1% got 3 correct answers, 40.9% answered only 2 questions correctly and 22.7% did not hit any. In post-test 45.4% answered all the questions right, 31.8% got 3 questions and 22.7% got 2 correct answers. The results show a significant improvement of the students about the field of content taught through the game. Conclusion: Generally, traditional approaches of chemistry and biochemistry are abstract and complex. Thus, through games

  9. Motivations for play in computer role-playing games

    DEFF Research Database (Denmark)

    Tychsen, Anders; Hitchens, Michael; Brolund, Thea

    2008-01-01

    In this paper the motivations for play in the context of single-and multi-player digital Role-Playing Games (RPGs) are examined. Survey data were drawn from respondents online and participants in a related experimental study. The results indicate that motivations for play are not simple constructs......, but rather composed of multiple motivational drivers that are heavily interrelated and act in concert. Character uniqueness and Discovery & Immersion were the highest ranked motivational categories. Different levels of detail in motivations for playing single-/multi- Player RPGs were located......, with mechanistic/tactical play and character-based/social play being the two overall motivational factors. Copyright 2008 ACM....

  10. The N-terminus of TDP-43 promotes its oligomerization and enhances DNA binding affinity

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chung-ke [Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan (China); Wu, Tzong-Huah [Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan (China); Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Institute of Biochemistry, Academia Sinica, Taipei 115, Taiwan (China); Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu 300, Taiwan (China); Wu, Chu-Ya [Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan (China); Graduate Institute of Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China); Chiang, Ming-hui; Toh, Elsie Khai-Woon [Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan (China); Hsu, Yin-Chih; Lin, Ku-Feng [Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan (China); Liao, Yu-heng [Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan (China); Huang, Tai-huang, E-mail: bmthh@gate.sinica.edu.tw [Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan (China); Department of Physics, National Taiwan Normal University, Taipei 106, Taiwan (China); Huang, Joseph Jen-Tse, E-mail: jthuang@chem.sinica.edu.tw [Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan (China)

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer The N-terminus of TDP-43 contains an independently folded structural domain (NTD). Black-Right-Pointing-Pointer The structural domains of TDP-43 are arranged in a beads-on-a-string fashion. Black-Right-Pointing-Pointer The NTD promotes TDP-43 oligomerization in a concentration-dependent manner. Black-Right-Pointing-Pointer The NTD may assist nucleic acid-binding activity of TDP-43. -- Abstract: TDP-43 is a DNA/RNA-binding protein associated with different neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD-U). Here, the structural and physical properties of the N-terminus on TDP-43 have been carefully characterized through a combination of nuclear magnetic resonance (NMR), circular dichroism (CD) and fluorescence anisotropy studies. We demonstrate for the first time the importance of the N-terminus in promoting TDP-43 oligomerization and enhancing its DNA-binding affinity. An unidentified structural domain in the N-terminus is also disclosed. Our findings provide insights into the N-terminal domain function of TDP-43.

  11. Zinc ion conducting polymer electrolytes based on oligomeric polyether/PVDF-HFP blends

    Science.gov (United States)

    Ye, Hui; Xu, Jun John

    Here we report novel zinc ion conducting polymer electrolytes based on oligomeric polyether/PVDF-HFP blends with or without the incorporation of a small amount of organic carbonates. Their thermal properties, ionic conductivity and electrochemical properties are characterized and the effect of different Zn salts and incorporation of a small amount of organic carbonates are investigated. These polymer electrolyte membranes exhibit essentially no or very low volatility, high thermal stability, high ionic conductivity, wide electrochemical stability window, acceptable interfacial resistance with zinc, and the capability for reversible Zn plating/stripping. Particularly promising are electrolyte systems based on the combination of low lattice energy zinc imide salt and a special co-solvent of oligomeric poly(ethylene glycol) dimethyl ether (PEGDME) mixed with a small amount of ethylene carbonate (EC), dimensionally stabilized with PVDF-HFP. Such novel polymer electrolyte membranes could lead to the development of new kinds of electrochemical energy storage devices based on zinc electrochemistry, including solid-state, thin-film rechargeable zinc/air cells envisaged.

  12. Zinc ion conducting polymer electrolytes based on oligomeric polyether/PVDF-HFP blends

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Hui; Xu, Jun John [Department of Materials Science and Engineering, Rutgers, the State University of New Jersey, Piscataway, NJ 08854 (United States)

    2007-03-20

    Here we report novel zinc ion conducting polymer electrolytes based on oligomeric polyether/PVDF-HFP blends with or without the incorporation of a small amount of organic carbonates. Their thermal properties, ionic conductivity and electrochemical properties are characterized and the effect of different Zn salts and incorporation of a small amount of organic carbonates are investigated. These polymer electrolyte membranes exhibit essentially no or very low volatility, high thermal stability, high ionic conductivity, wide electrochemical stability window, acceptable interfacial resistance with zinc, and the capability for reversible Zn plating/stripping. Particularly promising are electrolyte systems based on the combination of low lattice energy zinc imide salt and a special co-solvent of oligomeric poly(ethylene glycol) dimethyl ether (PEGDME) mixed with a small amount of ethylene carbonate (EC), dimensionally stabilized with PVDF-HFP. Such novel polymer electrolyte membranes could lead to the development of new kinds of electrochemical energy storage devices based on zinc electrochemistry, including solid-state, thin-film rechargeable zinc/air cells envisaged. (author)

  13. Oligomerization of SCFTIR1 Is Essential for Aux/IAA Degradation and Auxin Signaling in Arabidopsis.

    Science.gov (United States)

    Dezfulian, Mohammad H; Jalili, Espanta; Roberto, Don Karl A; Moss, Britney L; Khoo, Kerry; Nemhauser, Jennifer L; Crosby, William L

    2016-09-01

    The phytohormone auxin is a key regulator of plant growth and development. Molecular studies in Arabidopsis have shown that auxin perception and signaling is mediated via TIR1/AFB-Aux/IAA co-receptors that assemble as part of the SCFTIR1/AFB E3 ubiquitin-ligase complex and direct the auxin-regulated degradation of Aux/IAA transcriptional repressors. Despite the importance of auxin signaling, little is known about the functional regulation of the TIR1/AFB receptor family. Here we show that TIR1 can oligomerize in planta via a set of spatially clustered amino acid residues. While none of the residues identified reside in the interaction interface of the TIR1-Aux/IAA degron, they nonetheless regulate the binding of TIR1 to Aux/IAA substrate proteins and their subsequent degradation in vivo as an essential aspect of auxin signaling. We propose oligomerization of TIR1 as a novel regulatory mechanism in the regulation of auxin-mediated plant patterning and development.

  14. Glycation of Wild-Type Apomyoglobin Induces Formation of Highly Cytotoxic Oligomeric Species.

    Science.gov (United States)

    Iannuzzi, Clara; Carafa, Vincenzo; Altucci, Lucia; Irace, Gaetano; Borriello, Margherita; Vinciguerra, Roberto; Sirangelo, Ivana

    2015-11-01

    Protein glycation is a non-enzymatic, irreversible modification of protein amino groups by reactive carbonyl species leading to the formation of advanced glycation end products (AGEs). Several proteins implicated in neurodegenerative diseases have been found to be glycated in vivo and the extent of glycation is related to the pathologies of the patients. Although it is now accepted that there is a direct correlation between AGEs formation and the development of neurodegenerative diseases related to protein misfolding and amyloid aggregation, several questions still remain unanswered: whether glycation is the triggering event or just an additional factor acting on the aggregation pathway. We have recently shown that glycation of the amyloidogenic W7FW14F apomyoglobin mutant significantly accelerates the amyloid fibrils formation providing evidence that glycation actively participates to the process. In the present study, to test if glycation can be considered also a triggering factor in amyloidosis, we evaluated the ability of different glycation agents to induce amyloid aggregation in the soluble wild-type apomyoglobin. Our results show that glycation covalently modifies apomyoglobin and induces conformational changes that lead to the formation of oligomeric species that are not implicated in amyloid aggregation. Thus, AGEs formation does not trigger amyloid aggregation in the wild-type apomyoglobin but only induce the formation of soluble oligomeric species able to affect cell viability. The molecular bases of cell toxicity induced by AGEs formed upon glycation of wild-type apomyoglobin have been also investigated.

  15. Protein Cross-Linking and Oligomerization through Dityrosine Formation upon Exposure to Ozone.

    Science.gov (United States)

    Kampf, Christopher J; Liu, Fobang; Reinmuth-Selzle, Kathrin; Berkemeier, Thomas; Meusel, Hannah; Shiraiwa, Manabu; Pöschl, Ulrich

    2015-09-15

    Air pollution is a potential driver for the increasing prevalence of allergic disease, and post-translational modification by air pollutants can enhance the allergenic potential of proteins. Here, the kinetics and mechanism of protein oligomerization upon ozone (O3) exposure were studied in coated-wall flow tube experiments at environmentally relevant O3 concentrations, relative humidities and protein phase states (amorphous solid, semisolid, and liquid). We observed the formation of protein dimers, trimers, and higher oligomers, and attribute the cross-linking to the formation of covalent intermolecular dityrosine species. The oligomerization proceeds fast on the surface of protein films. In the bulk material, reaction rates are limited by diffusion depending on phase state and humidity. From the experimental data, we derive a chemical mechanism and rate equations for a kinetic multilayer model of surface and bulk reaction enabling the prediction of oligomer formation. Increasing levels of tropospheric O3 in the Anthropocene may promote the formation of protein oligomers with enhanced allergenicity and may thus contribute to the increasing prevalence of allergies.

  16. Quercetin Inhibits Inflammasome Activation by Interfering with ASC Oligomerization and Prevents Interleukin-1 Mediated Mouse Vasculitis

    Science.gov (United States)

    Domiciano, Talita P.; Wakita, Daiko; Jones, Heather D.; Crother, Timothy R.; Verri, Waldiceu A.; Arditi, Moshe; Shimada, Kenichi

    2017-01-01

    Interleukin-1β (IL-1β) is a highly inflammatory cytokine that significantly contributes to both acute and chronic inflammatory diseases. The secretion of IL-1β requires a unique protease, caspase-1, which is activated by various protein platforms called inflammasomes. Data suggests a key role for mitochondrial reactive oxygen species for inflammasome activation. Flavonoids constitute a group of naturally occurring polyphenolic molecules with many biological activities, including antioxidant effects. In this study, we investigated the effect of three flavonoids, quercetin (QUC), naringenin, and silymarim on inflammasome activation. We found that QUC inhibits IL-1β secretion by both the NLRP3 and AIM2 inflammasome in a dose dependent manner, but not the NLRC4 inflammasome. QUC inhibition of the inflammasome was still observed in Atg16l1 knockout macrophages, indicating that QUC’s effect was autophagy independent. Since QUC inhibited both NLRP3 and AIM2 inflammasomes but not NLRC4, we assessed ASC speck formation. QUC reduced ASC speck formation and ASC oligomerization compared with controls. Additionally, QUC inhibited IL-1β in Cryopyrin-Associated Periodic Syndromes (CAPS) macrophages, where NLRP3 inflammasome is constitutively activated. In conclusion, QUC inhibits both the NLRP3 and AIM2 inflammasome by preventing ASC oligomerization and may be a potential therapeutic candidate for Kawasaki disease vasculitis and other IL-1 mediated inflammatory diseases. PMID:28148962

  17. Characterization of Lassa virus glycoprotein oligomerization and influence of cholesterol on virus replication.

    Science.gov (United States)

    Schlie, Katrin; Maisa, Anna; Lennartz, Frank; Ströher, Ute; Garten, Wolfgang; Strecker, Thomas

    2010-01-01

    Mature glycoprotein spikes are inserted in the Lassa virus envelope and consist of the distal subunit GP-1, the transmembrane-spanning subunit GP-2, and the signal peptide, which originate from the precursor glycoprotein pre-GP-C by proteolytic processing. In this study, we analyzed the oligomeric structure of the viral surface glycoprotein. Chemical cross-linking studies of mature glycoprotein spikes from purified virus revealed the formation of trimers. Interestingly, sucrose density gradient analysis of cellularly expressed glycoprotein showed that in contrast to trimeric mature glycoprotein complexes, the noncleaved glycoprotein forms monomers and oligomers spanning a wide size range, indicating that maturation cleavage of GP by the cellular subtilase SKI-1/S1P is critical for formation of the correct oligomeric state. To shed light on a potential relation between cholesterol and GP trimer stability, we performed cholesterol depletion experiments. Although depletion of cholesterol had no effect on trimerization of the glycoprotein spike complex, our studies revealed that the cholesterol content of the viral envelope is important for the infectivity of Lassa virus. Analyses of the distribution of viral proteins in cholesterol-rich detergent-resistant membrane areas showed that Lassa virus buds from membrane areas other than those responsible for impaired infectivity due to cholesterol depletion of lipid rafts. Thus, derivation of the viral envelope from cholesterol-rich membrane areas is not a prerequisite for the impact of cholesterol on virus infectivity.

  18. Multicoil2: predicting coiled coils and their oligomerization states from sequence in the twilight zone.

    Directory of Open Access Journals (Sweden)

    Jason Trigg

    Full Text Available The alpha-helical coiled coil can adopt a variety of topologies, among the most common of which are parallel and antiparallel dimers and trimers. We present Multicoil2, an algorithm that predicts both the location and oligomerization state (two versus three helices of coiled coils in protein sequences. Multicoil2 combines the pairwise correlations of the previous Multicoil method with the flexibility of Hidden Markov Models (HMMs in a Markov Random Field (MRF. The resulting algorithm integrates sequence features, including pairwise interactions, through multinomial logistic regression to devise an optimized scoring function for distinguishing dimer, trimer and non-coiled-coil oligomerization states; this scoring function is used to produce Markov Random Field potentials that incorporate pairwise correlations localized in sequence. Multicoil2 significantly improves both coiled-coil detection and dimer versus trimer state prediction over the original Multicoil algorithm retrained on a newly-constructed database of coiled-coil sequences. The new database, comprised of 2,105 sequences containing 124,088 residues, includes reliable structural annotations based on experimental data in the literature. Notably, the enhanced performance of Multicoil2 is evident when tested in stringent leave-family-out cross-validation on the new database, reflecting expected performance on challenging new prediction targets that have minimal sequence similarity to known coiled-coil families. The Multicoil2 program and training database are available for download from http://multicoil2.csail.mit.edu.

  19. Integration and oligomerization of Bax protein in lipid bilayers characterized by single molecule fluorescence study.

    Science.gov (United States)

    Luo, Lu; Yang, Jun; Liu, Dongxiang

    2014-11-14

    Bax is a pro-apoptotic Bcl-2 family protein. The activated Bax translocates to mitochondria, where it forms pore and permeabilizes the mitochondrial outer membrane. This process requires the BH3-only activator protein (i.e. tBid) and can be inhibited by anti-apoptotic Bcl-2 family proteins such as Bcl-xL. Here by using single molecule fluorescence techniques, we studied the integration and oligomerization of Bax in lipid bilayers. Our study revealed that Bax can bind to lipid membrane spontaneously in the absence of tBid. The Bax pore formation undergoes at least two steps: pre-pore formation and membrane insertion. The activated Bax triggered by tBid or BH3 domain peptide integrates on bilayers and tends to form tetramers, which are termed as pre-pore. Subsequent insertion of the pre-pore into membrane is highly dependent on the composition of cardiolipin in lipid bilayers. Bcl-xL can translocate Bax from membrane to solution and inhibit the pore formation. The study of Bax integration and oligomerization at the single molecule level provides new evidences that may help elucidate the pore formation of Bax and its regulatory mechanism in apoptosis. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. Quercetin Inhibits Inflammasome Activation by Interfering with ASC Oligomerization and Prevents Interleukin-1 Mediated Mouse Vasculitis.

    Science.gov (United States)

    Domiciano, Talita P; Wakita, Daiko; Jones, Heather D; Crother, Timothy R; Verri, Waldiceu A; Arditi, Moshe; Shimada, Kenichi

    2017-02-02

    Interleukin-1β (IL-1β) is a highly inflammatory cytokine that significantly contributes to both acute and chronic inflammatory diseases. The secretion of IL-1β requires a unique protease, caspase-1, which is activated by various protein platforms called inflammasomes. Data suggests a key role for mitochondrial reactive oxygen species for inflammasome activation. Flavonoids constitute a group of naturally occurring polyphenolic molecules with many biological activities, including antioxidant effects. In this study, we investigated the effect of three flavonoids, quercetin (QUC), naringenin, and silymarim on inflammasome activation. We found that QUC inhibits IL-1β secretion by both the NLRP3 and AIM2 inflammasome in a dose dependent manner, but not the NLRC4 inflammasome. QUC inhibition of the inflammasome was still observed in Atg16l1 knockout macrophages, indicating that QUC's effect was autophagy independent. Since QUC inhibited both NLRP3 and AIM2 inflammasomes but not NLRC4, we assessed ASC speck formation. QUC reduced ASC speck formation and ASC oligomerization compared with controls. Additionally, QUC inhibited IL-1β in Cryopyrin-Associated Periodic Syndromes (CAPS) macrophages, where NLRP3 inflammasome is constitutively activated. In conclusion, QUC inhibits both the NLRP3 and AIM2 inflammasome by preventing ASC oligomerization and may be a potential therapeutic candidate for Kawasaki disease vasculitis and other IL-1 mediated inflammatory diseases.

  1. Structural insight into DNA binding and oligomerization of the multifunctional Cox protein of bacteriophage P2.

    Science.gov (United States)

    Berntsson, Ronnie P-A; Odegrip, Richard; Sehlén, Wilhelmina; Skaar, Karin; Svensson, Linda M; Massad, Tariq; Högbom, Martin; Haggård-Ljungquist, Elisabeth; Stenmark, Pål

    2014-02-01

    The Cox protein from bacteriophage P2 is a small multifunctional DNA-binding protein. It is involved in site-specific recombination leading to P2 prophage excision and functions as a transcriptional repressor of the P2 Pc promoter. Furthermore, it transcriptionally activates the unrelated, defective prophage P4 that depends on phage P2 late gene products for lytic growth. In this article, we have investigated the structural determinants to understand how P2 Cox performs these different functions. We have solved the structure of P2 Cox to 2.4 Å resolution. Interestingly, P2 Cox crystallized in a continuous oligomeric spiral with its DNA-binding helix and wing positioned outwards. The extended C-terminal part of P2 Cox is largely responsible for the oligomerization in the structure. The spacing between the repeating DNA-binding elements along the helical P2 Cox filament is consistent with DNA binding along the filament. Functional analyses of alanine mutants in P2 Cox argue for the importance of key residues for protein function. We here present the first structure from the Cox protein family and, together with previous biochemical observations, propose that P2 Cox achieves its various functions by specific binding of DNA while wrapping the DNA around its helical oligomer.

  2. STRUCTURAL BASIS FOR ALLOSTERIC REGULATION OF HUMAN RIBONUCLEOTIDE REDUCTASE BY NUCLEOTIDE-INDUCED OLIGOMERIZATION

    Science.gov (United States)

    Fairman, James Wesley; Wijerathna, Sanath Ranjan; Ahmad, Md. Faiz; Xu, Hai; Nakano, Ryo; Jha, Shalini; Prendergast, Jay; Welin, Martin; Flodin, Susanne; Roos, Annette; Nordlund, Pär; Li, Zongli; Walz, Thomas; Dealwis, Chris Godfrey

    2011-01-01

    Ribonucleotide reductase (RR) is an αnβn (RR1●RR2) complex that maintains balanced dNTP pools by reducing ribonucleoside diphosphates to deoxyribonucleoside diphosphates. RR1 is the catalytic subunit and RR2 houses the free radical required for catalysis. RR is allosterically regulated by its activator ATP and its inhibitor dATP, which regulate RR activity by inducing oligomerization of RR1. Here, we report the first X-ray structures of human RR1 bound to TTP-only, dATP-only, TTP●GDP, TTP●ATP, and TTP●dATP. These structures provide insights into ATP/dATP regulation of RR. At physiological dATP concentrations, RR1 forms inactive hexamers. We determined the first X-ray structure of the RR1●dATP hexamer and used single-particle electron microscopy to visualize the α6●ββ’ 1●dATP holo complex. Site-directed mutagenesis and functional assays confirm that hexamerization is a prerequisite for inhibition by dATP. Our data provide an elegant mechanism for regulating RR activity by dATP-induced oligomerization. PMID:21336276

  3. The oligomeric Rep protein of Mungbean yellow mosaic India virus (MYMIV) is a likely replicative helicase.

    Science.gov (United States)

    Choudhury, Nirupam Roy; Malik, Punjab Singh; Singh, Dharmendra Kumar; Islam, Mohammad Nurul; Kaliappan, Kosalai; Mukherjee, Sunil Kumar

    2006-01-01

    Geminiviruses replicate by rolling circle mode of replication (RCR) and the viral Rep protein initiates RCR by the site-specific nicking at a conserved nonamer (TAATATT downward arrow AC) sequence. The mechanism of subsequent steps of the replication process, e.g. helicase activity to drive fork-elongation, etc. has largely remained obscure. Here we show that Rep of a geminivirus, namely, Mungbean yellow mosaic India virus (MYMIV), acts as a replicative helicase. The Rep-helicase, requiring > or =6 nt space for its efficient activity, translocates in the 3'-->5' direction, and the presence of forked junction in the substrate does not influence the activity to any great extent. Rep forms a large oligomeric complex and the helicase activity is dependent on the oligomeric conformation ( approximately 24mer). The role of Rep as a replicative helicase has been demonstrated through ex vivo studies in Saccharomyces cerevisiae and in planta analyses in Nicotiana tabacum. We also establish that such helicase activity is not confined to the MYMIV system alone, but is also true with at least two other begomoviruses, viz., Mungbean yellow mosaic virus (MYMV) and Indian cassava mosaic virus (ICMV).

  4. Lipid-II Independent Antimicrobial Mechanism of Nisin Depends On Its Crowding And Degree Of Oligomerization

    Science.gov (United States)

    Prince, Ashutosh; Sandhu, Padmani; Kumar, Pankaj; Dash, Eva; Sharma, Shingarika; Arakha, Manoranjan; Jha, Suman; Akhter, Yusuf; Saleem, Mohammed

    2016-11-01

    Nisin inhibits bacterial growth by generating pores in cell membrane and interrupting cell-wall biosynthesis through specific lipid II interaction. However, the role of the hinge region and C-terminus residues of the peptide in antibacterial action of nisin is largely unknown. Here, using molecular dynamics simulations and experimental approach, we report that at high concentration regimes of nisin, interaction with phospholipids may equally deform the bacterial cell membranes even under significantly varying amounts of lipid-II. Membrane thinning, destabilization and decrease in lipid density depend on the degree of oligomerization of nisin. Growth kinetics of Bacillus subtilis and Escherichia coli interestingly show recovery by extended lag phase under low concentrations of nisin treatment while high concentrations of nisin caused decrease in cell viability as recorded by striking reduction in membrane potential and surface area. The significant changes in the dipole potential and fluorescence anisotropy were observed in negatively charged membranes in the absence of lipid-II with increasing concentration of nisin. The identical correlation of cell viability, membrane potential dissipation and morphology with the concentration regime of nisin, in both Bacillus subtilis (lipid II rich) and Escherichia coli (lipid II impoverished), hints at a non-specific physical mechanism where degree of membrane deformation depends on degree of crowding and oligomerization of nisin.

  5. SYNTHESIS AND CHARACTERIZATION OF A NOVEL REACTIVE OLIGOMERIC LADDERLIKE COPOLYMETHYL-AMINOPROPYL SILSESQUIOXANE

    Institute of Scientific and Technical Information of China (English)

    Qing-hua Duan; Tao-yi Zhang; Kui-lin Deng; Ping Xie; Rong-ben Zhang

    2005-01-01

    A novel ordered reactive oligomeric ladderlike copolymethyl-aminopropylsilsesquioxane (Me-AP-T), was successfully synthesized by an efficient hydrosilylation graft reaction of 1,1,1-trimethyl-N-2-propenyl-silanamine with a reactive oligomeric ladderlike copolymethyl-hydrosilsesquioxane (Me-H-T), which was prepared by "supramolecular chemistry-dictated stepwise coupling polymerization" process. FT-IR, 1H- and 29Si-NMR spectra show that hydrosilylation reaction proceeds completely. Moreover, 1H-NMR spectra also indicate that both the molar ratios of ≡SiMe group to Si-H and ≡ SiMe group to ≡ SiPrNH2 are approximately 1:1 respectively based on the ratio of integrated resonance areas of the different groups. XRD analysis and 29Si-NMR spectra are used for investigating the ladderlike structure of the polymers. A high Tg (128.38℃) of Me-AP-T shown in DSC measurement implies that the ordered reactive Me-AP-T macromolecules have much stiff chains.

  6. Apolipoprotein E, especially apolipoprotein E4, increases the oligomerization of amyloid β peptide.

    Science.gov (United States)

    Hashimoto, Tadafumi; Serrano-Pozo, Alberto; Hori, Yukiko; Adams, Kenneth W; Takeda, Shuko; Banerji, Adrian Olaf; Mitani, Akinori; Joyner, Daniel; Thyssen, Diana H; Bacskai, Brian J; Frosch, Matthew P; Spires-Jones, Tara L; Finn, Mary Beth; Holtzman, David M; Hyman, Bradley T

    2012-10-24

    Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder causing dementia. Massive deposition of amyloid β peptide (Aβ) as senile plaques in the brain is the pathological hallmark of AD, but oligomeric, soluble forms of Aβ have been implicated as the synaptotoxic component. The apolipoprotein E ε 4 (apoE ε4) allele is known to be a genetic risk factor for developing AD. However, it is still unknown how apoE impacts the process of Aβ oligomerization. Here, we found that the level of Aβ oligomers in APOE ε4/ε4 AD patient brains is 2.7 times higher than those in APOE ε3/ε3 AD patient brains, matched for total plaque burden, suggesting that apoE4 impacts the metabolism of Aβ oligomers. To test this hypothesis, we examined the effect of apoE on Aβ oligomer formation. Using both synthetic Aβ and a split-luciferase method for monitoring Aβ oligomers, we observed that apoE increased the level of Aβ oligomers in an isoform-dependent manner (E2 apoE4, increases Aβ oligomers in the brain. Higher levels of Aβ oligomers in the brains of APOE ε4/ε4 carriers compared with APOE ε3/ε3 carriers may increase the loss of dendritic spines and accelerate memory impairments, leading to earlier cognitive decline in AD.

  7. Characterization of oligomeric procyanidins and identification of quercetin glucuronide from lotus ( Nelumbo nucifera Gaertn.) seedpod.

    Science.gov (United States)

    Xiao, Jun-Song; Xie, Bi-Jun; Cao, Yan-Ping; Wu, Hua; Sun, Zhi-Da; Xiao, Di

    2012-03-21

    Procyanidins are a class of polyphenols in the plant kingdom. Lotus ( Nelumbo nucifera Gaertn.) seedpods, the inedible part of lotus and a byproduct during the production of lotus seeds, were found to be a new source rich in procyanidins. Detailed information about oligomeric procyanidins in lotus seedpods remains unknown. In this study, lotus seedpods were extracted using 60% aqueous methanol and characterized with phloroglucinolysis and liquid chromatography (mass spectrometry with an electrospray ionization source). The results indicate that the oligomeric and polymeric fraction had a mean degree of polymerization of 3.2 and 15.4, respectively, and consisted of (+)-catechin (m/z 289), gallocatechin or epigallocatechin (m/z 305), quercetin glycoside (m/z 463), quercetin glucuronide (m/z 477), procyanidin dimers (m/z 577.1), proanthocyanidin dimer gallate (m/z 593.3), prodelphinidin dimers (m/z 609.1), procyanidin trimers (m/z 865.1), etc. Quercetin glucuronide was further purified using flash chromatography and identified as quercetin-3-O-β-glucuronide by determining its exact mass using ion-trap time-of-flight mass spectrometry and ¹H and ¹³C nuclear magnetic resonance, ¹H-detected heteronuclear single-quantum coherence, and ¹H-detected heteronuclear multiple-bond correlation analyses.

  8. Redox and metal-regulated oligomeric state for human porphobilinogen synthase activation.

    Science.gov (United States)

    Sawada, N; Nagahara, N; Arisaka, F; Mitsuoka, K; Minami, M

    2011-06-01

    The oligomeric state of human porphobilinogen synthase (PBGS) [EC.4.2.1.24] is homooctamer, which consists of conformationally heterogenous subunits in the tertiary structure under air-saturated conditions. When PBGS is activated by reducing agent with zinc ion, a reservoir zinc ion coordinated by Cys(223) is transferred in the active center to be coordinated by Cys(122), Cys(124), and Cys(132) (Sawada et al. in J Biol Inorg Chem 10:199-207, 2005). The latter zinc ion serves as an electrophilic catalysis. In this study, we investigated a conformational change associated with the PBGS activation by reducing agent and zinc ion using analytical ultracentrifugation, negative staining electron microscopy, native PAGE, and enzyme activity staining. The results are in good agreement with our notion that the main component of PBGS is octamer with a few percent of hexamer and that the octamer changes spatial subunit arrangement upon reduction and further addition of zinc ion, accompanying decrease in f/f (0). It is concluded that redox-regulated PBGS activation via cleavage of disulfide bonds among Cys(122), Cys(124), and Cys(132) and coordination with zinc ion is closely linked to change in the oligomeric state.

  9. Dealuminated ZSM—5 Zeolite Catalyst for Ethylene Oligomerization to Liquid Fuels

    Institute of Scientific and Technical Information of China (English)

    NorAishahSaidinaAmin; DidiDwiAnggoro

    2002-01-01

    Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Broensted acid sites in the formation of higher hydrocarbons,The oligomeriztion of olefins,dependent on the acidity of ZSM-5 zeolite ,is an important step in the conversion of natural gas to liquied fuels,The framework Si/Al ratio reflects the number of potential acid sites and the acid strength of the ZSM-5 catalyst,ZSM-5 with the mole ratio SiO2/Al2O3 equal to 30 was dealuminated for different periods of time according to the acidic ion-exchange method to produce ZSM-5 with various Si/Al ratios,The FT-IR analysis revealed that the integrated framework aluminum band,non-framework aluminum band,and silanol groups areas of the ZSM-5 zeolites decreased after being dealuminated,The performanc of the dealuminated zeolite was tested for ethylene oligomerization.The results demonstrated that the dealumination of ZSM-5 led to higher ethylene conversion,but the gasoline selectivity was reduced compared to the performance of a ZSM-5 zeolite ,The characterization results revealed the amount of aluminum in the zeolitic framework,the crystallinity of the ZSM-5 zeolite,and the Si/Al ration affected the formation of Broensted acid sites,The number of the Broensted acid sites on the catalyst active sites is important in the olefin conversion to liquied hydrocarbons.

  10. Oligomerization of Glycine and Alanine Catalyzed by Iron Oxides: Implications for Prebiotic Chemistry

    Science.gov (United States)

    Shanker, Uma; Bhushan, Brij; Bhattacharjee, G.; Kamaluddin

    2012-02-01

    Iron oxide minerals are probable constituents of the sediments present in geothermal regions of the primitive earth. They might have adsorbed different organic monomers (amino acids, nucleotides etc.) and catalyzed polymerization processes leading to the formation of the first living cell. In the present work we tested the catalytic activity of three forms of iron oxides (Goethite, Akaganeite and Hematite) in the intermolecular condensation of each of the amino acids glycine and L-alanine. The effect of zinc oxide and titanium dioxide on the oligomerization has also been studied. Oligomerization studies were performed for 35 days at three different temperatures 50, 90 and 120°C without applying drying/wetting cycling. The products formed were characterized by HPLC and ESI-MS techniques. All three forms of iron oxides catalyzed peptide bond formation (23.2% of gly2 and 10.65% of ala2). The reaction was monitored every 7 days. Formation of peptides was observed to start after 7 days at 50°C. Maximum yield of peptides was found after 35 days at 90°C. Reaction at 120°C favors formation of diketopiperazine derivatives. It is also important to note that after 35 days of reaction, goethite produced dimer and trimer with the highest yield among the oxides tested. We suggest that the activity of goethite could probably be due to its high surface area and surface acidity.

  11. Synthesis and Characterization of A Polynuclear Yttrium Trifluoroethoxide and Its Activity for Oligomerization of Phenyl Isocyanate

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A polynuclear yttrium trifluoroethoxide was synthesized and its activity for the oligomerization of phenyl isocyanate was tested. Reaction of anhydrous YCl3 with CF3CH2ONa in a 1:3 molar ratio in THF at room temperature, after workup, gave complex 1 as colorless crystals. The composition of complex 1 is [Y(OCH2CF3)3]6ONa2(THF)12, which was identified by elemental analysis and 1H NMR. Further X-ray structure determination reveals that complex 1 is a polynuclear ion pair compound, [Y6(μ6-O)(OCH2CF3)18]2-[Na(THF)6]+2 (1). The crystal data of complex 1 are trigonal, P-3 space group, a=1.78440(14) nm, b=1.78440(14) nm, c=1.27395(12) nm, γ=120°, V=3.5129(5) nm3, Z=1, Dc=1.607 mg·m-3, μ=2.591 mm-1 (Mo Kα), F(000)=1710, R=0.067, wR=0.182. Preliminary results demonstrated that complex 1 is a highly effective catalyst for the oligomerization of phenyl isocyanate.

  12. Influence of oligomeric silsesquioxane coating treatment on interfacial properties of CF/PAA composites

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xuezhong; HUANG Yudong; WANG Tianyu; HU Lijiang

    2007-01-01

    Carbon fibres (CF) were modified with different oligomeric silsesquioxane (SSO) coatings to improve the interfacial property of carbon fibres/polyarylacetylene (CF/PAA).The interlaminar shear strength (ILSS) of CF/PAA was tested to determine the effect of the treatment.Atomic force microscopy (AFM) in force modulation mode was adopted to study the cross-section surface of unidirectional CF/PAA composites and the relative stiffness of various phases, including CF,interphase and resin.The probability histogram and line distribution of CF/PAA cross-section surface relative stiffness,obtained from the statistical analysis of relative stiffness image,were used to compare and study the interface characterizations of composites.The results show that the ILSS increases effectively and the effects on interfacial characterizations are distinguished from each other in accor-dance with the CF surface modified with different SSO coatings owing to the various structures.Cage oligomeric silsesquioxane,including large organic groups (methacryl isobutyl-POSS),has better treatment result.AFM observa-tions lead to the conclusion that an interfacial transition layer with different morphology and stiffness appears in CF/PAA composites after being treated by the SSO coatings of different structures.It can be inferred that the appearance of the transition layer may contribute to the improvement of fibre/matrix adhesion.

  13. Development of a fast atom bombardment tandem mass spectrometric screening method for alkyl-ended oligomeric biguanides

    Science.gov (United States)

    Monaghan, J. J.; Morden, W. E.

    1992-12-01

    The FAB-MS and FAB-MS---MS behaviour of a series of "alkyl-ended" oligomeric biguanides has been studied. MS---MS product ion scans showed that fragmentation of these species occurred by predictable cleavages of the biguanide chains. Results are presented from a number of MS---MS precursor ion and neutral loss scans studied in an attempt to develop a screening method for biguanides in complex mixtures. The most effective of these scans is shown to be the neutral loss of the N-alkylguanidine molecule. Use of this scan is demonstrated for a mixture of oligomeric biguanides.

  14. Regulation of complement by cartilage oligomeric matrix protein allows for a novel molecular diagnostic principle in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Happonen, Kaisa E; Saxne, Tore; Aspberg, Anders;

    2010-01-01

    Cartilage oligomeric matrix protein (COMP) is a structural component of cartilage, where it catalyzes collagen fibrillogenesis. Elevated amounts of COMP are found in serum during increased turnover of cartilage associated with active joint disease, such as rheumatoid arthritis (RA) and osteoarthr......Cartilage oligomeric matrix protein (COMP) is a structural component of cartilage, where it catalyzes collagen fibrillogenesis. Elevated amounts of COMP are found in serum during increased turnover of cartilage associated with active joint disease, such as rheumatoid arthritis (RA......) and osteoarthritis (OA). This study was undertaken to investigate the ability of COMP to regulate complement, a capacity that has previously been shown for some other cartilage proteins....

  15. Catalysis of the Oligomerization of O-Phospho-Serine, Aspartic Acid, or Glutamic Acid by Cationic Micelles

    Science.gov (United States)

    Boehler, Christof; Hill, Aubrey R., Jr.; Orgel, Leslie E.

    1996-01-01

    Treatment of relatively concentrated aqueous solutions of O-phospho-serine (50 mM), aspartic acid (100 mM) or glutamic acid (100 mM) with carbonyldiimidazole leads to the formation of an activated intermediate that oligomerizes efficiently. When the concentration of amino acid is reduced tenfold, few long oligomers can be detected. Positively-charged cetyltrimethyl ammonium bromide micelles concentrate the negatively-charged activated intermediates of the amino acids at their surfaces and catalyze efficient oligomerization even from dilute solutions.

  16. Structural Insight for Roles of DR5 Death Domain Mutations on Oligomerization of DR5 Death Domain-FADD Complex in the Death-Inducing Signaling Complex Formation: A Computational Study.

    Science.gov (United States)

    Yang, Hongyi; Song, Yuhua

    2016-04-01

    Death receptor 5 (DR5)-induced apoptosis that prioritizes the death of tumor cells has been proposed as one of the promising cancer therapies. In this process, oligomerized DR5 death domain (DD) binding to Fas-associated death domain (FADD) leads to FADD activating caspase-8, which marks the formation of the death-inducing signaling complex (DISC) that initiates apoptosis. DR5 DD mutations found in cancer cells have been suggested to play an important pathological role, the mechanism through which those mutants prevent the DR5-activated DISC formation is not clear yet. This study sought to provide structural and molecular insight for the roles of four selected DR5 DD mutations (E355K, E367K, K415N, and L363F) in the oligomerization of DR5 DD-FADD complex during the DISC formation. Results from the molecular dynamics simulations show that the simulated mutants induce conformational, dynamical motions and interactions changes in the DR5 DD-FADD tetramer complex, including changes in a protein's backbone flexibility, less exposure of FADD DED's caspase-8 binding site, reduced H-bonding and hydrophobic contacts at the DR5 DD-FADD DD binding, altered distribution of the electrostatic potentials and correlated motions of residues, and reduced binding affinity of DR5 DD binding to FADD. This study provides structural and molecular insight for the influence of DR5 DD mutations on oligomerization of DR5 DD-FADD complex, which is expected to foster understanding of the DR5 DD mutants' resistance mechanism against DR5-activated DISC formation.

  17. Solar Power at Play

    Science.gov (United States)

    2007-03-01

    For the very first time, astronomers have witnessed the speeding up of an asteroid's rotation, and have shown that it is due to a theoretical effect predicted but never seen before. The international team of scientists used an armada of telescopes to discover that the asteroid's rotation period currently decreases by 1 millisecond every year, as a consequence of the heating of the asteroid's surface by the Sun. Eventually it may spin faster than any known asteroid in the solar system and even break apart. ESO PR Photo 11a/07 ESO PR Photo 11a/07 Asteroid 2000 PH5 "The Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect is believed to alter the way small bodies in the Solar System rotate," said Stephen Lowry (Queens University Belfast, UK), lead-author of one of the two companion papers in which this work is reported [1, 2]. "The warming caused by sunlight hitting the surfaces of asteroids and meteoroids leads to a gentle recoil effect as the heat is released," he added. "By analogy, if one were to shine light on a propeller over a long enough period, it would start spinning." Although this is an almost immeasurably weak force, its effect over millions of years is far from negligible. Astronomers believe the YORP effect may be responsible for spinning some asteroids up so fast that they break apart, perhaps leading to the formation of double asteroids. Others may be slowed down so that they take many days to complete a full turn. The YORP effect also plays an important role in changing the orbits of asteroids between Mars and Jupiter, including their delivery to planet-crossing orbits, such as those of near-Earth asteroids. Despite its importance, the effect has never been seen acting on a solar system body, until now. Using extensive optical and radar imaging from powerful Earth-based observatories, astronomers have directly observed the YORP effect in action on a small near-Earth asteroid, known as (54509) 2000 PH5. Shortly after its discovery in 2000, it was

  18. Play technique in psychodynamic psychotherapy.

    Science.gov (United States)

    Yanof, Judith A

    2013-04-01

    Imaginary play is often a child's best way of communicating affects, fantasies, and internal states. In play children are freer to express their forbidden and conflicted thoughts. Consequently, one of the best ways for the therapist to enter the child's world is to do so from within the displacement of the play process. For children who cannot play, the therapist's goal is to teach the child to use play as a means of communication and to create meaning. This article present clinical examples to illustrate how the author uses play in the clinical situation.

  19. Bispecific antibodies directed to CD4 domain 2 and HIV envelope exhibit exceptional breadth and picomolar potency against HIV-1.

    Science.gov (United States)

    Pace, Craig S; Song, Ruijiang; Ochsenbauer, Christina; Andrews, Chasity D; Franco, David; Yu, Jian; Oren, Deena A; Seaman, Michael S; Ho, David D

    2013-08-13

    In the absence of an effective HIV-1 vaccine, passive immunization using broadly neutralizing Abs or Ab-like molecules could provide an alternative to the daily administration of oral antiretroviral agents that has recently shown promise as preexposure prophylaxis. Currently, no single broadly neutralizing Ab (bNAb) or combination of bNAbs neutralizes all HIV-1 strains at practically achievable concentrations in vivo. To address this problem, we created bispecific Abs that combine the HIV-1 inhibitory activity of ibalizumab (iMab), a humanized mAb directed to domain 2 of human CD4, with that of anti-gp120 bNAbs. These bispecific bNAbs (BibNAbs) exploit iMab's potent anti-HIV-1 activity and demonstrated clinical efficacy and safety to anchor and thereby concentrate a second broadly neutralizing agent at the site of viral entry. Two BibNabs, PG9-iMab and PG16-iMab, exhibit exceptional breadth and potency, neutralizing 100% of the 118 viruses tested at low picomolar concentrations, including viruses resistant to both parental mAbs. The enhanced potency of these BibNAbs was entirely dependent on CD4 anchoring, not on membrane anchoring per se, and required optimal Ab geometry and linker length. We propose that iMab-based BibNAbs, such as PG9-iMab and PG16-iMab, are promising candidates for passive immunization to prevent HIV-1 infection.

  20. Identification of a positively evolving putative binding region with increased variability in posttranslational motifs in zonadhesin MAM domain 2.

    Science.gov (United States)

    Herlyn, Holger; Zischler, Hans

    2005-10-01

    Positive selection has been shown to be pervasive in sex-related proteins of many metazoan taxa. However, we are only beginning to understand molecular evolutionary processes on the lineage to humans. To elucidate the evolution of proteins involved in human reproduction, we studied the sequence evolution of MAM domains of the sperm-ligand zonadhesin in respect to single amino acid sites, solvent accessibility, and posttranslational modification. GenBank-data were supplemented by new cDNA-sequences of a representative non-human primate panel. Solvent accessibility predictions identified a probably exposed fragment of 30 amino acids belonging to MAM domain 2 (i.e., MAM domain 3 in mouse). The fragment is characterized by significantly increased rate of positively selected amino acid sites and exhibits high variability in predicted posttranslational modification, and, thus, might represent a binding region in the mature protein. At the same time, there is a significant coincidence of positively selected amino acid sites and non-conserved posttranslational motifs. We conclude that the binding specificity of zonadhesin MAM domains, especially of the presumed epitope, is achieved by positive selection at the level of single amino acid sites and posttranslational modifications, respectively.

  1. Learning, Play, and Your Newborn

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old Learning, Play, and Your Newborn KidsHealth > For Parents > Learning, ... juega su recién nacido What Is My Newborn Learning? Play is the chief way that infants learn ...

  2. Problematic Game Play: The Diagnostic Value of Playing Motives, Passion, and Playing Time in Men

    Directory of Open Access Journals (Sweden)

    Julia Kneer

    2015-04-01

    Full Text Available Internet gaming disorder is currently listed in the DSM—not in order to diagnose such a disorder but to encourage research to investigate this phenomenon. Even whether it is still questionable if Internet Gaming Disorder exists and can be judged as a form of addiction, problematic game play is already very well researched to cause problems in daily life. Approaches trying to predict problematic tendencies in digital game play have mainly focused on playing time as a diagnostic criterion. However, motives to engage in digital game play and obsessive passion for game play have also been found to predict problematic game play but have not yet been investigated together. The present study aims at (1 analyzing if obsessive passion can be distinguished from problematic game play as separate concepts, and (2 testing motives of game play, passion, and playing time for their predictive values for problematic tendencies. We found (N = 99 males, Age: M = 22.80, SD = 3.81 that obsessive passion can be conceptually separated from problematic game play. In addition, the results suggest that compared to solely playing time immersion as playing motive and obsessive passion have added predictive value for problematic game play. The implications focus on broadening the criteria in order to diagnose problematic playing.

  3. The Importance of Being Playful.

    Science.gov (United States)

    Bodrova, Elena; Leong, Deborah J.

    2003-01-01

    Recent research provides evidence of the strong connections between quality of play in preschool years and children's readiness for school instruction. Mature play, characterized by imaginary situations, multiple roles, clearly defined rules, flexible themes, language development, length of play, helps students' cognitive development. (Contains 12…

  4. Play in Evolution and Development

    Science.gov (United States)

    Pellegrini, Anthony D.; Dupuis, Danielle; Smith, Peter K.

    2007-01-01

    In this paper we examine the role of play in human ontogeny and phylogeny, following Surplus Resource Theory. We consider how juveniles use play to sample their environment in order to develop adaptive behaviors. We speculate about how innovative behaviors developed in play in response to environmental novelty may influence subsequent evolutionary…

  5. Pretend Play and Creative Processes

    Science.gov (United States)

    Russ, Sandra W.; Wallace, Claire E.

    2013-01-01

    The authors contend that many cognitive abilities and affective processes important in creativity also occur in pretend play and that pretend play in childhood affects the development of creativity in adulthood. They discuss a variety of theories and observations that attempt to explain the importance of pretend play to creativity. They argue that…

  6. Styrene oligomerization as a molecular probe reaction for zeolite acidity: a UV-Vis spectroscopy and DFT study

    NARCIS (Netherlands)

    Buurmans, I.L.C.; Pidko, E.A.; de Groot, J.M.; Stavitski, I.; van Santen, R.A.; Weckhuysen, B.M.

    2013-01-01

    A series of H-ZSM-5 crystallites with different framework Si/Al ratios was studied by analyzing the kinetics and reaction mechanism of the oligomerization of 4-fluorostyrene as molecular probe reaction for Brønsted acidity. The formation of carbocationic species was followed by UV-Vis spectroscopy.

  7. The upstream conserved regions (UCRs) mediate homo- and hetero-oligomerization of type 4 cyclic nucleotide phosphodiesterases (PDE4s).

    Science.gov (United States)

    Xie, Moses; Blackman, Brigitte; Scheitrum, Colleen; Mika, Delphine; Blanchard, Elise; Lei, Tao; Conti, Marco; Richter, Wito

    2014-05-01

    PDE4s (type 4 cyclic nucleotide phosphodiesterases) are divided into long and short forms by the presence or absence of conserved N-terminal domains termed UCRs (upstream conserved regions). We have shown previously that PDE4D2, a short variant, is a monomer, whereas PDE4D3, a long variant, is a dimer. In the present study, we have determined the apparent molecular masses of various long and short PDE4 variants by size-exclusion chromatography and sucrose density-gradient centrifugation. Our results indicate that dimerization is a conserved property of all long PDE4 forms, whereas short forms are monomers. Dimerization is mediated by the UCR domains. Given their high sequence conservation, the UCR domains mediate not only homo-oligomerization, but also hetero-oligomerization of distinct PDE4 long forms as detected by co-immunoprecipitation assays and FRET microscopy. Endogenous PDE4 hetero-oligomers are, however, low in abundance compared with homo-dimers, revealing the presence of mechanisms that predispose PDE4s towards homo-oligomerization. Oligomerization is a prerequisite for the regulatory properties of the PDE4 long forms, such as their PKA (protein kinase A)-dependent activation, but is not necessary for PDE4 protein-protein interactions. As a result, individual PDE4 protomers may independently mediate protein-protein interactions, providing a mechanism whereby PDE4s contribute to the assembly of macromolecular signalling complexes.

  8. Disulphide bond restrains the C-terminal region of thermostable direct hemolysin during folding to promote oligomerization.

    Science.gov (United States)

    Kundu, Nidhi; Tichkule, Swapnil; Pandit, Shashi Bhushan; Chattopadhyay, Kausik

    2017-01-15

    Pore-forming toxins (PFTs) are typically produced as water-soluble monomers, which upon interacting with target cells assemble into transmembrane oligomeric pores. Vibrio parahaemolyticus thermostable direct hemolysin (TDH) is an atypical PFT that exists as a tetramer in solution, prior to membrane binding. The TDH structure highlights a core β-sandwich domain similar to those found in the eukaryotic actinoporin family of PFTs. However, the TDH structure harbors an extended C-terminal region (CTR) that is not documented in the actinoporins. This CTR remains tethered to the β-sandwich domain through an intra-molecular disulphide bond. Part of the CTR is positioned at the inter-protomer interface in the TDH tetramer. Here we show that the truncation, as well as mutation, of the CTR compromise tetrameric assembly, and the membrane-damaging activity of TDH. Our study also reveals that intra-protomer disulphide bond formation during the folding/assembly process of TDH restrains the CTR to mediate its participation in the formation of inter-protomer contact, thus facilitating TDH oligomerization. However, once tetramerization is achieved, disruption of the disulphide bond does not affect oligomeric assembly. Our study provides critical insights regarding the regulation of the oligomerization mechanism of TDH, which has not been previously documented in the PFT family.

  9. A Small-Molecule Inhibitor of Bax and Bak Oligomerization Prevents Genotoxic Cell Death and Promotes Neuroprotection.

    Science.gov (United States)

    Niu, Xin; Brahmbhatt, Hetal; Mergenthaler, Philipp; Zhang, Zhi; Sang, Jing; Daude, Michael; Ehlert, Fabian G R; Diederich, Wibke E; Wong, Eve; Zhu, Weijia; Pogmore, Justin; Nandy, Jyoti P; Satyanarayana, Maragani; Jimmidi, Ravi K; Arya, Prabhat; Leber, Brian; Lin, Jialing; Culmsee, Carsten; Yi, Jing; Andrews, David W

    2017-04-20

    Aberrant apoptosis can lead to acute or chronic degenerative diseases. Mitochondrial outer membrane permeabilization (MOMP) triggered by the oligomerization of the Bcl-2 family proteins Bax/Bak is an irreversible step leading to execution of apoptosis. Here, we describe the discovery of small-molecule inhibitors of Bax/Bak oligomerization that prevent MOMP. We demonstrate that these molecules disrupt multiple, but not all, interactions between Bax dimer interfaces thereby interfering with the formation of higher-order oligomers in the MOM, but not recruitment of Bax to the MOM. Small-molecule inhibition of Bax/Bak oligomerization allowed cells to evade apoptotic stimuli and rescued neurons from death after excitotoxicity, demonstrating that oligomerization of Bax is essential for MOMP. Our discovery of small-molecule Bax/Bak inhibitors provides novel tools for the investigation of the mechanisms leading to MOMP and will ultimately facilitate development of compounds inhibiting Bax/Bak in acute and chronic degenerative diseases. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Permeability Changes of Manduca sexta Midgut Brush Border Membranes Induced by Oligomeric Structures of Different Cry Toxins

    NARCIS (Netherlands)

    Muñoz-Garay, C.; Sánchez, J.; Darszon, A.; Maagd, de R.A.; Bakker, P.; Soberón, M.; Bravo, A.

    2006-01-01

    The pore-formation activity of monomeric and oligomeric forms of different Cry1 toxins (from Cry1A to Cry1G) was analyzed by monitoring ionic permeability across Manduca sexta brush border membrane vesicles. The membrane vesicles were isolated from microvilli structures, showing a high enrichment of

  11. Recognition of coxiella burnetii by toll-like receptors and nucleotide-binding oligomerization domain-like receptors

    NARCIS (Netherlands)

    Ammerdorffer, Anne; Schoffelen, Teske; Gresnigt, Mark S.; Oosting, Marije; Brok, Den Martijn H.; Abdollahi-Roodsaz, Shahla; Kanneganti, Thirumala Devi; Jong, De Dirk J.; Deuren, Van Marcel; Roest, Hendrik Jan; Rebel, Johanna M.J.; Netea, Mihai G.; Joosten, Leo A.B.; Sprong, Tom

    2015-01-01

    Background. Infection with Coxiella burnetii can lead to acute and chronic Q fever. Toll-like receptor 1 (TLR1), TLR2, TLR4, TLR6, nucleotide-binding oligomerization domain receptor 1 (NOD1), NOD2, and the mitogen-activated protein kinases are central in the innate immune response against

  12. Recognition of Coxiella burnetii by Toll-like Receptors and Nucleotide-Binding Oligomerization Domain-like Receptors

    NARCIS (Netherlands)

    Ammerdorffer, A.; Schoffelen, T.; Gresnigt, M.S.; Oosting, M.; Brok, M.H.M.G.M. den; Abdollahi-Roodsaz, S.; Kanneganti, T.D.; Jong, D.J. de; Deuren, M. van; Roest, H.J.; Rebel, J.M.; Netea, M.G.; Joosten, L.A.B.; Sprong, T.

    2015-01-01

    BACKGROUND: Infection with Coxiella burnetii can lead to acute and chronic Q fever. Toll-like receptor 1 (TLR1), TLR2, TLR4, TLR6, nucleotide-binding oligomerization domain receptor 1 (NOD1), NOD2, and the mitogen-activated protein kinases are central in the innate immune response against

  13. Interference with RUNX1/ETO Leukemogenic Function by Cell-Penetrating Peptides Targeting the NHR2 Oligomerization Domain

    Directory of Open Access Journals (Sweden)

    Yvonne Bartel

    2013-01-01

    Full Text Available The leukemia-associated fusion protein RUNX1/ETO is generated by the chromosomal translocation t(8;21 which appears in about 12% of all de novo acute myeloid leukemias (AMLs. Essential for the oncogenic potential of RUNX1/ETO is the oligomerization of the chimeric fusion protein through the nervy homology region 2 (NHR2 within ETO. In previous studies, we have shown that the intracellular expression of peptides containing the NHR2 domain inhibits RUNX1/ETO oligomerization, thereby preventing cell proliferation and inducing differentiation of RUNX1/ETO transformed cells. Here, we show that introduction of a recombinant TAT-NHR2 fusion polypeptide into the RUNX1/ETO growth-dependent myeloid cell line Kasumi-1 results in decreased cell proliferation and increased numbers of apoptotic cells. This effect was highly specific and mediated by binding the TAT-NHR2 peptide to ETO sequences, as TAT-polypeptides containing the oligomerization domain of BCR did not affect cell proliferation or apoptosis in Kasumi-1 cells. Thus, the selective interference with NHR2-mediated oligomerization by peptides represents a challenging but promising strategy for the inhibition of the leukemogenic potential of RUNX1/ETO in t(8;21-positive leukemia.

  14. Interference with RUNX1/ETO Leukemogenic Function by Cell-Penetrating Peptides Targeting the NHR2 Oligomerization Domain

    Science.gov (United States)

    Bartel, Yvonne; Grez, Manuel; Wichmann, Christian

    2013-01-01

    The leukemia-associated fusion protein RUNX1/ETO is generated by the chromosomal translocation t(8;21) which appears in about 12% of all de novo acute myeloid leukemias (AMLs). Essential for the oncogenic potential of RUNX1/ETO is the oligomerization of the chimeric fusion protein through the nervy homology region 2 (NHR2) within ETO. In previous studies, we have shown that the intracellular expression of peptides containing the NHR2 domain inhibits RUNX1/ETO oligomerization, thereby preventing cell proliferation and inducing differentiation of RUNX1/ETO transformed cells. Here, we show that introduction of a recombinant TAT-NHR2 fusion polypeptide into the RUNX1/ETO growth-dependent myeloid cell line Kasumi-1 results in decreased cell proliferation and increased numbers of apoptotic cells. This effect was highly specific and mediated by binding the TAT-NHR2 peptide to ETO sequences, as TAT-polypeptides containing the oligomerization domain of BCR did not affect cell proliferation or apoptosis in Kasumi-1 cells. Thus, the selective interference with NHR2-mediated oligomerization by peptides represents a challenging but promising strategy for the inhibition of the leukemogenic potential of RUNX1/ETO in t(8;21)-positive leukemia. PMID:23865046

  15. The Solvent Effect on the Chemoselectivity of Palladium-catalyzed Oligomerization of 3, 3-Dimethyl-1-butyne

    Institute of Scientific and Technical Information of China (English)

    Jin Sheng CHENG; Jin Heng LI; Huan Feng JIANG; Xiao Yue OUYANG

    2003-01-01

    The chemoselectivities of PdC12 and CuC12-catalyzed oligomerization of 3, 3-dimethyl-butyne: 1, 3, 5-tri-tert-butylbenzene, 2, 2, 7, 7-tetramethyl-3, 6-dichloro-3, 5-octadiene and 2, 2, 7,7- tetramethyl-3,5-octadiyne were obtained, respectively, by regulating the polarity of the solvent.

  16. Structure of viroid replicative intermediates: physico-chemical studies on SP6 transcripts of cloned oligomeric potato spindle tuber viroid.

    Science.gov (United States)

    Steger, G; Tabler, M; Brüggemann, W; Colpan, M; Klotz, G; Sänger, H L; Riesner, D

    1986-12-22

    The structure and structural transitions of transcripts of cloned oligomeric viroid were studied in physico-chemical experiments and stability calculations. Transcripts of (+) and (-) polarity, from unit up to sixfold length, were synthesized from DNA clones of the potato spindle tuber viroid (PSTV) with the SP6 transcription system. Their structural properties were investigated by optical denaturation curves, high performance liquid chromatography (HPLC), electron microscopy, sedimentation-diffusion equilibrium and velocity sedimentation. Secondary structures of the RNAs and theoretical denaturation curves were calculated using an energy optimization program. The secondary structure of lowest free energy for unit length and oligomeric transcripts is a rod-like structure similar to that of the mature circular viroids. When this structure is used as a model for calculations, there is a large degree of agreement between the theoretical and the experimental denaturation curves. At high temperatures, however, (+) strand transcripts exhibited a transition which was more stable than expected from the calculations or than was known from curves of mature viroids. This transition arises from a rearrangement of the central conserved region of viroids to a helical region of 28 stable base pairs either intermolecularly leading to bimolecular complexes, or intramolecularly giving rise to a branched secondary structure. The rearrangement could be detected by electron microscopy, HPLC, and analytical ultracentrifugation. The helical region serves to divide up the oligomeric (+) strand into structural units which may be recognized by cleavage and ligation enzymes which process the oligomeric intermediates to circular mature viroids.

  17. A rapid, semi-quantitative assay to screen for modulators of alpha-synuclein oligomerization ex vivo

    Directory of Open Access Journals (Sweden)

    Marion eDelenclos

    2016-01-01

    Full Text Available Alpha synuclein (αsyn aggregates are associated with the pathogenesis of Parkinson’s disease and others related disorders. Although modulation of αsyn aggregation is an attractive therapeutic target, new powerful methodologies are desperately needed to facilitate in vivo screening of novel therapeutics. Here we describe an in vivo rodent model with the unique ability to rapidly track αsyn-αsyn interactions and thus oligomerization using a bioluminescent protein complementation strategy that monitors spatial and temporal αsyn oligomerization ex vivo. We find that αsyn forms oligomers in vivo as early as 1 week after stereotactic AAV injection into rat substantia nigra. Strikingly, although abundant αsyn expression is also detected in striatum at one week, no αsyn oligomers are detected at this time point. By 4 weeks, oligomerization of αsyn is detected in both striatum and substantia nigra homogenates. Moreover, in a proof-of-principle experiment, the effect of a previously described Hsp90 inhibitor known to prevent αsyn oligomer formation, demonstrates the utility of this rapid and sensitive animal model to monitor αsyn oligomerization status in the rat brain.

  18. α-Helical domain is essential for antimicrobial activity of high mobility group nucleosomal binding domain 2 (HMGN2)

    Institute of Scientific and Technical Information of China (English)

    Yun FENG; Ning HUANG; Qi WU; Lang BAO; Bo-yao WANG

    2005-01-01

    Aim: To examine the antimicrobial spectrum and functional structure of high mobility group nucleosomal binding domain 2 (HMGN2). Methods: OMIGA protein structure software was used to analyze the two-dimensional structure of HMGN2. Synthetic short peptides were generated for studying the relationship between function and structure. Prokaryotic expression vectors were constructed for the holo-HMGN2 and its helical domain. Their E coli-based products were also prepared for antimicrobial testing. The antimicrobial assay included minimal effective concentration, minimal inhibitory concentration, and minimal bactericidal concentration. Results: OMIGA protein structure software analysis revealed a transmembrane α-helical structure (the putative antimicrobial domain) located from position 18 to 48 of the HMGN2 protein sequence. The antimicrobial assay showed that the MIC of the recombinant holo-HMGN2 against E coli ML-35p (an ampicillin-resistance strain), Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 10231 were 12.5, 25, and 100 mg/L, respectively. Against the same microorganisms, the MIC of the synthetic HMGN2 α-helical domain were 12.5, 25,and 100 mg/L, respectively, that is, the same as with the recombinant form of HMGN2. In contrast, recombinant holo-HMGN2 was inactive against Staphylococcus aureus ATCC 25923. The synthetic N-terminal and C-terminal fragments of HMGN2 had no antimicrobial activity against E coli ML-35p, P aeruginosa ATCC 27853 or C albicans ATCC 10231. Conclusion: HMGN2 showed potent antimicrobial activity against E coli ML-35p, P aeruginosa ATCC 27853 and, to some extent, against C albicans ATCC 10231, but was inactive against S aureus ATCC 25923 in these assay systems. Its α-helical structure may be essential for the antimicrobial activity of HMGN2.

  19. Oligomerization of Vibrio cholerae Hemolysin Induces CXCR3 Upregulation and Activation of B-1a Cell

    Institute of Scientific and Technical Information of China (English)

    Gayatri Mukherjee; Kalyan K Banerjee; Tapas Biswas

    2008-01-01

    The hemolysin oligomer promotes the proliferation of B-1a cells and the expression of CD25, which is indicative of cell activation, on B-1a cells. The upregulation of CD86 induced by the oligomer showed its selective bias for the B7-2 member of B7 family while the monomer failed to induce these effects. The oligomer induced the expression of CXCR3, associated with B cell activation, while the monomer induced the expression of CXCL4, a powerful angiostatic chemokine. In conclusion, we found that B-1a cells responded to the apoptogenic monomer by expressing CXCL4, whereas oligomerization of the immunogen induced CXCR3 to shift the response towards activation. Cellular & Molecular Immunology. 2008;5(3):231-234.

  20. Efficient light-emitting devices based on platinum-complexes-anchored polyhedral oligomeric silsesquioxane materials

    KAUST Repository

    Yang, Xiaohui

    2010-08-24

    The synthesis, photophysical, and electrochemical characterization of macromolecules, consisting of an emissive platinum complex and carbazole moieties covalently attached to a polyhedral oligomeric silsesquioxane (POSS) core, is reported. Organic light-emitting devices based on these POSS materials exhibit a peak external quantum efficiency of ca. 8%, which is significantly higher than that of the analogous devices with a physical blend of the platinum complexes and a polymer matrix, and they represent noticeable improvement in the device efficiency of solution-processable phosphorescent excimer devices. Furthermore, the ratio of monomer and excimer/aggregate electroluminescent emission intensity, as well as the device efficiency, increases as the platinum complex moiety presence on the POSS macromolecules decreases. © 2010 American Chemical Society.

  1. Entropic estimate of cooperative binding of substrate on a single oligomeric enzyme: An index of cooperativity

    CERN Document Server

    Banerjee, Kinshuk; Gangopadhyay, Gautam

    2012-01-01

    Here we have systematically studied the cooperative binding of substrate molecules on the active sites of a single oligomeric enzyme in a chemiostatic condition. The average number of bound substrate and the net velocity of the enzyme catalyzed reaction are studied by the formulation of stochastic master equation for the cooperative binding classified here as spatial and temporal. We have estimated the entropy production for the cooperative binding schemes based on single trajectory analysis using a kinetic Monte Carlo technique. It is found that the total as well as the medium entropy production show the same generic diagnostic signature for detecting the cooperativity, usually characterized in terms of the net velocity of the reaction. This feature is also found to be valid for the total entropy production rate at the nonequilibrium steady state. We have introduced an index of cooperativity, C, defined in terms of the ratio of the surprisals or equivalently, the stochastic system entropy associated with the...

  2. Energetic Calculations to Decipher pH-Dependent Oligomerization and Domain Swapping of Proteins.

    Science.gov (United States)

    Shingate, Prashant; Warwicker, Jim; Sowdhamini, Ramanathan

    2015-01-01

    Domain swapping mechanism is a specialised mode of oligomerization of proteins in which part of a protein is exchanged in a non-covalent manner between constituent subunits. This mechanism is highly affected by several physiological conditions. Here, we present a detailed analysis ofthe effect of pH on different regions of the domain swapped oligomer by considering examples which are known to be sensitive to pH in transiting from monomeric to domain-swapped dimeric form. The energetic calculations were performed using a specialized method which considers changes in pH and subsequent changes in the interactions between subunits. This analysis provides definitive hints about the pH-dependence switch from monomer to domain-swapped oligomer and the steps that may be involved in the swapping mechanism.

  3. Pattern transfer during deposition and fixation of oligomeric bisphenol A on pre-structured copper surfaces.

    Science.gov (United States)

    Szillat, Florian; Fechner, Renate; Mayr, Stefan G

    2013-09-01

    Pattern transfer during deposition of oligomeric bisphenol A (OBA) on pre-structured Cu surfaces is investigated by means of a combined experimental-computational approach. Aiming for quantitative prediction of experiments, as characterized by atomic force microscopy (AFM), we explore the capabilities of stochastic rate equations to quantitatively account for the spatio-temporal evolution of surface topography. While surface diffusion and deposition noise constitute the main mechanisms, pattern transfer is affected by the inclusion of retardation in the interface potential, which appears to be necessary beyond a critical initial surface slope. In addition, routes for successful surface fixation by cross-linking are also demonstrated, which may pave the way for further technological use.

  4. The Role of Nucleotide-Binding Oligomerization Domain-Like Receptors in Pulmonary Infection.

    Science.gov (United States)

    Wiese, Kristin M; Coates, Bria M; Ridge, Karen M

    2017-08-01

    Pneumonia is caused by both viral and bacterial pathogens and is responsible for a significant health burden in the Unites States. The innate immune system is the human body's first line of defense against these pathogens. The recognition of invading pathogens via pattern recognition receptors leads to proinflammatory cytokine and chemokine production, followed by recruitment and activation of effector immune cells. The nonspecific inflammatory nature of the innate immune response can result in immunopathology that is detrimental to the host. In this review, we focus on one class of pattern recognition receptors, the nucleotide-binding oligomerization domain (NOD)-like receptors, specifically NOD1 and NOD2, and their role in host defense against viral and bacterial pathogens of the lung, including influenza, respiratory syncytial virus, Streptococcus pneumoniae, Chlamydophila pneumoniae, and Staphylococcus aureus. It is hoped that improved understanding of NOD1 and NOD2 activity in pneumonia will facilitate the development of novel therapies and promote improved patient outcomes.

  5. Building blocks of the apoptotic pore: how Bax and Bak are activated and oligomerize during apoptosis

    Science.gov (United States)

    Westphal, D; Kluck, R M; Dewson, G

    2014-01-01

    The central role of the Bcl-2 family in regulating apoptotic cell death was first identified in the 1980s. Since then, significant in-roads have been made in identifying the multiple members of this family, characterizing their form and function and understanding how their interactions determine whether a cell lives or dies. In this review we focus on the recent progress made in characterizing the proapoptotic Bcl-2 family members, Bax and Bak. This progress has resolved longstanding controversies, but has also challenged established theories in the apoptosis field. We will discuss different models of how these two proteins become activated and different ‘modes' by which they are inhibited by other Bcl-2 family members. We will also discuss novel conformation changes leading to Bak and Bax oligomerization and speculate how these oligomers might permeabilize the mitochondrial outer membrane. PMID:24162660

  6. Energetic Calculations to Decipher pH-Dependent Oligomerization and Domain Swapping of Proteins.

    Directory of Open Access Journals (Sweden)

    Prashant Shingate

    Full Text Available Domain swapping mechanism is a specialised mode of oligomerization of proteins in which part of a protein is exchanged in a non-covalent manner between constituent subunits. This mechanism is highly affected by several physiological conditions. Here, we present a detailed analysis ofthe effect of pH on different regions of the domain swapped oligomer by considering examples which are known to be sensitive to pH in transiting from monomeric to domain-swapped dimeric form. The energetic calculations were performed using a specialized method which considers changes in pH and subsequent changes in the interactions between subunits. This analysis provides definitive hints about the pH-dependence switch from monomer to domain-swapped oligomer and the steps that may be involved in the swapping mechanism.

  7. Assembly of the intrinsic factor domains and oligomerization of the protein in the presence of cobalamin

    DEFF Research Database (Denmark)

    Fedosov, Sergey N; Fedosova, Natalya U; Berglund, Lars;

    2004-01-01

    oligomerized. A mixture of two fragments IF(30) + IF(20) and Cbl produced a firm complex, IF(30+20).Cbl, which could not associate to dimers. In contrast to IF(30+20).Cbl, the saturated full-length monomers IF(50).Cbl dimerized with K(d) approximately 1 microM. We suggest a two-domain organization of the full......-length protein, where two distant units, IF(30) and IF(20), can be assembled only by Cbl. They are connected by a protease-sensitive link, whose native structure is likely to be important for dimerization. However, linkage between two domains is not compulsory for Cbl binding. Advantages of the two...

  8. Synthesis and characterization of luminescent organic-inorganic hybrid nanocomposite from polyhedral oligomeric silsesquioxane

    Institute of Scientific and Technical Information of China (English)

    Yan

    2010-01-01

    A novel polyhedral oligomeric silsesquioxane (POSS)-based organic-inorganic hybrid nanocomposite (EF-POSS) was prepared by Pt-catalyzed hydrosilylation reaction of octahydridosilsesquioxane (T8H8, POSS) with a luminescent substituted acetylene (2-ethynyl-7-(4-(4-methylstyryl)styryl)-9,9-dioctyl-9H-fluorene (EF)) in high yield. The hybrid nanocomposite was soluble in common solvents such as CH2Cl2, CHCl3, THF and 1,4-dioxane. Its structure and property were characterized by FTIR, NMR, TGA, UV and PL, respectively. The results show that the hybrid nanocomposite with high thermal stability emits stable blue light as a result of photo excitation and possesses high photoluminescence quantum efficiency (φfL).

  9. Properties of PMR Polyimides Improved by Preparation of Polyhedral Oligomeric Silsesquioxane (POSS) Nanocomposites

    Science.gov (United States)

    Campbell, Sandi G.; Lee, Andre

    2005-01-01

    The field of hybrid organic-inorganic materials has grown drastically over the last several years. This interest stems from our ever-increasing ability to custom-build and control molecular structure at several length scales. This ability to control both the composition and structure of hybrid materials is sometimes broadly referred to as nanocomposite systems. One class of hybrid (organic-inorganic) nanostructured material is polyhedral oligomeric silsesquioxane (POSS), shown in the preceding diagram. The hybrid composition gives POSS materials dramatically enhanced properties relative to traditional hydrocarbons and inorganics. An important benefit of this technology is that it makes possible the formulations of nanostructured chemicals with excellent thermal and oxidative stability. This is largely due to the inorganic component.

  10. Chalcane-stilbene conjugates and oligomeric flavonoids from Chinese Dragon's Blood produced from Dracaena cochinchinensis.

    Science.gov (United States)

    Hao, Qian; Saito, Yoshinori; Matsuo, Yosuke; Li, Hai-Zhou; Tanaka, Takashi

    2015-11-01

    A detailed chemical investigation of Chinese Dragon's Blood, which is a traditional medicine produced form the red resin of Dracaena cochinchinensis, yielded two chalcane-stilbene conjugates, named cochinchinenenes G and H, together with 25 known compounds. The structures of these compounds were determined by spectroscopic examination. HPLC analysis of the resin indicated that the major constituents were a complex mixture of oligomeric polyphenols, which were detected as a broad hump on the base line of a HPLC chromatogram. (13)C NMR analysis indicated that the oligomers were mainly composed of oxygenated chalcane units. This suggestion was supported by the results of a thiol degradation experiment with mercaptoethanol, which yielded a thioether of 4-[(4-hydroxyphenyl)propyl]-3-methoxyphenol. Furthermore, methylation followed by electrospray ionization mass spectroscopic analysis of the resulting fractions established the presence of at least one heptamer of chalcane units. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Auto-oligomerization and hydration of pyrrole revealed by x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Advanced Light Source; Schwartz, Craig P.; Uejio, Janel S.; Duffin, Andrew M.; England, Alice H.; Prendergast, David; Saykally, Richard J

    2009-05-29

    Near edge x-ray absorption fine structure (NEXAFS) spectra have been measured at the carbon and nitrogen K-edges of the prototypical aromatic molecule, pyrrole, both in the gas phase and when solvated in water, and compared with spectra simulated using a combination of classical molecular dynamics and first principles density functional theory in the excited state core hole approximation. The excellent agreement enabled detailed assignments. Pyrrole is highly reactive, particularly in water, and reaction products formed by the auto-oligomerization of pyrrole are identified. The solvated spectra have been measured at two different temperatures, indicating that the final states remain largely unaffected by both hydration and temperature. This is somewhat unexpected, since the nitrogen in pyrrole can donate a hydrogen bond to water.

  12. Tunable Gravimetric and Volumetric Hydrogen Storage Capacities in Polyhedral Oligomeric Silsesquioxane Frameworks.

    Science.gov (United States)

    Deshmukh, Amol; Chiu, Cheng-Chau; Chen, Yun-Wen; Kuo, Jer-Lai

    2016-09-28

    We study the hydrogen adsorption in porous frameworks composed of silsesquioxane cages linked via boron substituted aromatic structures by first-principles modeling. Such polyhedral oligomeric silsesquioxane (POSS) frameworks can be further modified by decorating them with metal atoms binding to the ring structures of the linkers. We have considered Sc- and Ti-doped frameworks which bind H2 via so-called Kubas interaction between hydrogen molecules and transition metal atoms. It will be demonstrated that the maximum H2 gravimetric capacity can be improved to more than 7.5 wt % by using longer linkers with more ring structures. However, the maximum H2 volumetric capacity can be tuned to more than 70 g/L by varying the size of silsesquioxane cages. We are optimistic that by varying the building blocks, POSS frameworks can be modified to meet the targets for the gravimetric and volumetric capacities set by the U.S. Department of Energy.

  13. Radiation-induced pink nickel oligomeric clusters in water. Pulse radiolysis study.

    Science.gov (United States)

    Hioul, Mohamed Larbi; Lin, Mingzhang; Belloni, Jacqueline; Keghouche, Nassira; Marignier, Jean-Louis

    2014-10-09

    γ-rays and pulse radiolysis of aqueous solutions of Ni(2+) ions in the presence of polyacrylate (PA(-)) and 2-propanol leads to the formation of metastable species absorbing at 540 nm that are ascribed to "pink" oligomeric clusters of a few nickel atoms only. The molar absorption coefficient is evaluated as ε540 nm = 3300 ± 300 L mol(-1) cm(-1) per Ni(0) atom. The successive steps from the reduction of Ni(2+) into Ni(+) ions to the formation of the pink clusters at 540 nm under conditions of complexation by PA(-) are investigated by pulse radiolysis. The yield of the formation of pink clusters increases markedly with the irradiation dose rate, demonstrating the occurrence of the disproportionation of the [Ni(+), PA(-)] complex after a single electron pulse. The reduction and nucleation mechanisms, including rate constants, in competition with the back oxidation by protons, particularly at low dose rate, are discussed.

  14. Understanding Controls on Wetting at Fluorinated Polyhedral Oligomeric Silsesquioxane/Polymer Surfaces.

    Science.gov (United States)

    Ye, Yi; Tian, Ming; Zhang, Chen; Du, Zhongjie; Mi, Jianguo

    2016-01-12

    Fluorinated polyhedral oligomeric silsesquioxane (F-POSS) nanoparticles have been widely used to enhance the hydrophobicity or oleophobicity of polymer films via constructing the specific micro/nanoscale roughness. In this work, we study the oleophobicity of pure and F-POSS-decorated poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) films using a dynamic density functional theory approach. The role of nanoparticle size and coverage and the chemical features of F-POSS and the polymer film in the wetting behavior of diiodomethane droplets has been integrated to the remaining ratio of surface potential to quantitatively characterize the corner effect. It is shown that, on the basis of universal force field parameters, the theoretically predicted contact angles are in general agreement with the available experimental data.

  15. Oligomeric α-synuclein and β-amyloid variants as potential biomarkers for Parkinson's and Alzheimer's diseases.

    Science.gov (United States)

    Williams, Stephanie M; Schulz, Philip; Sierks, Michael R

    2016-01-01

    Oligomeric forms of α-synuclein and β-amyloid are toxic protein variants that are thought to contribute to the onset and progression of Parkinson's disease (PD) and Alzheimer's disease (AD), respectively. The detection of toxic variants in human cerebrospinal fluid (CSF) and blood has great promise for facilitating early and accurate diagnoses of these devastating diseases. Two hurdles that have impeded the use of these protein variants as biomarkers are the availability of reagents that can bind the different variants and a sensitive assay to detect their very low concentrations. We previously isolated antibody-based reagents that selectively bind two different oligomeric variants of α-synuclein and two of β-amyloid, and developed a phage-based capture enzyme-linked immunosorbent assay (ELISA) with subfemtomolar sensitivity to quantify their presence. Here, we used these reagents to show that these oligomeric α-synuclein variants are preferentially present in PD brain tissue, CSF and serum, and that the oligomeric β-amyloid variants are preferentially present in AD brain tissue, CSF, and serum. Some AD samples also had α-synuclein pathology and some PD samples also had β-amyloid pathology, and, very intriguingly, these PD cases also had a history of dementia. Detection of different oligomeric α-synuclein and β-amyloid species is an effective method for identifying tissue, CSF and sera from PD and AD samples, respectively, and samples that also contained early stages of other protein pathologies, indicating their potential value as blood-based biomarkers for neurodegenerative diseases.

  16. The protective effects and underlying mechanism of an anti-oligomeric Aβ42 single-chain variable fragment antibody.

    Science.gov (United States)

    Zhang, Yuan; Chen, Xu; Liu, Jinyu; Zhang, Yingjiu

    2015-12-01

    Oligomeric Aβ42 aggregates have been identified as one of the major neurotoxic components of Alzheimer's disease (AD). Immunotherapy targeted against these Aβ42 aggregates has been proposed as an appropriate therapeutic approach for the treatment of AD. Here, we report an anti-oligomeric Aβ42 single-chain variable fragment (scFv) antibody, named MO6, obtained from the human antibody library of a healthy donor. ScFv MO6 specifically recognized and bound to the oligomeric Aβ42 (Aβ42 oligomers and immature protofibrils; 18-37 kDa), and reduced their levels mainly by blocking their formation, although scFv MO6 also induced disaggregation of Aβ42 aggregates. More importantly, scFv MO6 ameliorated or attenuated Aβ42-induced cytotoxicity and increased cell viability by up to 33%. Furthermore, scFv MO6 efficiently passed through an in vitro blood-brain barrier (BBB) model with a delivery efficiency of 66% after 60 min post-administration. ScFv MO6 is a monovalent antibody with an affinity constant (KD) of 5.2×10(-6) M for Aβ42 oligomers. Molecular docking simulations of Aβ42 to scFv MO6 revealed that the approach and specific binding of scFv MO6 to oligomeric Aβ42 aggregates was achieved by conformational recognition and directed induction, which resulted in a more dynamic adaptation of Aβ42 to scFv MO6, occurring mainly in the N-terminal (3-4), middle (12-19) and C-terminal (34-42) regions of Aβ42. This binding mode of scFv MO6 to Aβ42 explains its protective effects against oligomeric Aβ42. Our findings may be applied for the design of a smaller antibody specific for Aβ42 oligermers.

  17. Uncoupling of allosteric and oligomeric regulation in a functional hybrid enzyme constructed from Escherichia coli and human ribonucleotide reductase.

    Science.gov (United States)

    Fu, Yuan; Long, Marcus J C; Rigney, Mike; Parvez, Saba; Blessing, William A; Aye, Yimon

    2013-10-08

    An N-terminal-domain (NTD) and adjacent catalytic body (CB) make up subunit-α of ribonucleotide reductase (RNR), the rate-limiting enzyme for de novo dNTP biosynthesis. A strong linkage exists between ligand binding at the NTD and oligomerization-coupled RNR inhibition, inducible by both dATP and nucleotide chemotherapeutics. These observations have distinguished the NTD as an oligomeric regulation domain dictating the assembly of inactive RNR oligomers. Inactive states of RNR differ between eukaryotes and prokaryotes (α6 in human versus α4β4 in Escherichia coli , wherein β is RNR's other subunit); however, the NTD structurally interconnects individual α2 or α2 and β2 dimeric motifs within the respective α6 or α4β4 complexes. To elucidate the influence of NTD ligand binding on RNR allosteric and oligomeric regulation, we engineered a human- E. coli hybrid enzyme (HE) where human-NTD is fused to E. coli -CB. Both the NTD and the CB of the HE bind dATP. The HE specifically partners with E. coli -β to form an active holocomplex. However, although the NTD is the sole physical tether to support α2 and/or β2 associations in the dATP-bound α6 or α4β4 fully inhibited RNR complexes, the binding of dATP to the HE NTD only partially suppresses HE activity and fully precludes formation of higher-order HE oligomers. We postulate that oligomeric regulation is the ultimate mechanism for potent RNR inhibition, requiring species-specific NTD-CB interactions. Such interdomain cooperativity in RNR oligomerization is unexpected from structural studies alone or biochemical studies of point mutants.

  18. Motivations for play in computer role-playing games

    DEFF Research Database (Denmark)

    Tychsen, Anders; Hitchens, Michael; Brolund, Thea

    2008-01-01

    In this paper the motivations for play in the context of single-and multi-player digital Role-Playing Games (RPGs) are examined. Survey data were drawn from respondents online and participants in a related experimental study. The results indicate that motivations for play are not simple constructs......, but rather composed of multiple motivational drivers that are heavily interrelated and act in concert. Character uniqueness and Discovery & Immersion were the highest ranked motivational categories. Different levels of detail in motivations for playing single-/multi- Player RPGs were located...

  19. Functional role of oligomerization for bacterial and plant SWEET sugar transporter family.

    Science.gov (United States)

    Xuan, Yuan Hu; Hu, Yi Bing; Chen, Li-Qing; Sosso, Davide; Ducat, Daniel C; Hou, Bi-Huei; Frommer, Wolf B

    2013-09-24

    Eukaryotic sugar transporters of the MFS and SWEET superfamilies consist of 12 and 7 α-helical transmembrane domains (TMs), respectively. Structural analyses indicate that MFS transporters evolved from a series of tandem duplications of an ancestral 3-TM unit. SWEETs are heptahelical proteins carrying a tandem repeat of 3-TM separated by a single TM. Here, we show that prokaryotes have ancestral SWEET homologs with only 3-TM and that the Bradyrhizobium japonicum SemiSWEET1, like Arabidopsis SWEET11, mediates sucrose transport. Eukaryotic SWEETs most likely evolved by internal duplication of the 3-TM, suggesting that SemiSWEETs form oligomers to create a functional pore. However, it remains elusive whether the 7-TM SWEETs are the functional unit or require oligomerization to form a pore sufficiently large to allow for sucrose passage. Split ubiquitin yeast two-hybrid and split GFP assays indicate that Arabidopsis SWEETs homo- and heterooligomerize. We examined mutant SWEET variants for negative dominance to test if oligomerization is necessary for function. Mutation of the conserved Y57 or G58 in SWEET1 led to loss of activity. Coexpression of the defective mutants with functional A. thaliana SWEET1 inhibited glucose transport, indicating that homooligomerization is necessary for function. Collectively, these data imply that the basic unit of SWEETs, similar to MFS sugar transporters, is a 3-TM unit and that a functional transporter contains at least four such domains. We hypothesize that the functional unit of the SWEET family of transporters possesses a structure resembling the 12-TM MFS structure, however, with a parallel orientation of the 3-TM unit.

  20. Aqueous SOA formation from radical oligomerization of methyl vinyl ketone (MVK) and methacrolein (MACR)

    Science.gov (United States)

    Renard, P.; Siekmann, F.; Ravier, S.; Temime-Roussel, B.; Clément, J.; Ervens, B.; Monod, A.

    2013-12-01

    It is now accepted that one of the important pathways of secondary organic aerosol (SOA) formation occurs through aqueous phase chemistry in the atmosphere. However, the chemical mechanisms leading to macromolecules are still not well understood. It was recently shown that oligomer production by OH radical oxidation in the aerosol aqueous phase from α-dicarbonyl precursors, such as methylglyoxal and glyoxal, is irreversible and fast. We have investigated the aqueous phase photooxidation of MACR and MVK, which are biogenic organic compounds derived from isoprene. Aqueous phase photooxidation of MVK and MACR was investigated in a photoreactor using photolysis of H2O2 as OH radical source. Electrospray high resolution mass spectrometry analysis of the solutions brought clear evidence for the formation of oligomer systems having a mass range of up to 1800 Da within less than 15 minutes of reaction. Highest oligomer formation rates were obtained under conditions of low dissolved oxygen, highest temperature (T = 298 K) and highest precursor initial concentrations ([MVK]0 = 20 mM). A radical mechanism of oligomerization is proposed to explain the formation of the high molecular weight products. Furthermore, we quantified the total amount of carbon present in oligomers. Kinetic parameters of the proposed oligomerization mechanism are constrained by means of a box model that is able to reproduce the temporal evolution of intermediates and products as observed in the laboratory experiments. Additional model simulations for atmospherically-relevant conditions will be presented that show the extent to which these radical processes contribute to SOA formation in the atmospheric multiphase system as compared to other aqueous phase as well as traditional SOA sources. MVK time profile (as measured by UV Spectroscopy) and mass spectra (obtained using UPLC-ESI-MS for the retention time range 0-5 min in the positive mode) at 5, 10 and 50 min of reaction (MVK 20 mM, 25° C, under

  1. Core-6 fucose and the oligomerization of the 1918 pandemic influenza viral neuraminidase

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhengliang L., E-mail: Leon.wu@bio-techne.com [Bio-Techne Inc., 614 McKinley Place NE, Minneapolis, MN 55413 (United States); Zhou, Hui [Gregg Hall, UNH Glycomics Center, University of New Hampshire (United States); Ethen, Cheryl M. [Bio-Techne Inc., 614 McKinley Place NE, Minneapolis, MN 55413 (United States); Reinhold, Vernon N., E-mail: Vernon.Reinhold@unh.edu [Gregg Hall, UNH Glycomics Center, University of New Hampshire (United States)

    2016-04-29

    The 1918 H1N1 influenza virus was responsible for one of the most deadly pandemics in human history. Yet to date, the structure component responsible for its virulence is still a mystery. In order to search for such a component, the neuraminidase (NA) antigen of the virus was expressed, which led to the discovery of an active form (tetramer) and an inactive form (dimer and monomer) of the protein due to different glycosylation. In this report, the N-glycans from both forms were released and characterized by mass spectrometry. It was found that the glycans from the active form had 26% core-6 fucosylated, while the glycans from the inactive form had 82% core-6 fucosylated. Even more surprisingly, the stalk region of the active form was almost completely devoid of core-6-linked fucose. These findings were further supported by the results obtained from in vitro incorporation of azido fucose and {sup 3}H-labeled fucose using core-6 fucosyltransferase, FUT8. In addition, the incorporation of fucose did not change the enzymatic activity of the active form, implying that core-6 fucose is not directly involved in the enzymatic activity. It is postulated that core-6 fucose prohibits the oligomerization and subsequent activation of the enzyme. - Graphical abstract: Proposed mechanism for how core-fucose prohibits the tetramerization of the 1918 pandemic viral neuraminidase. Only the cross section of the stalk region with two N-linked glycans are depicted for clarity. (A) Carbohydrate–carbohydrate interaction on non-fucosylated monomer allows tetramerization. (B) Core-fucosylation disrupts the interaction and prevents the tetramerization. - Highlights: • Expressed 1918 pandemic influenza viral neuraminidase has inactive and active forms. • The inactive form contains high level of core-6 fucose, while the active form lacks such modification. • Core fucose could interfere the oligomerization of the neuraminidase and thus its activation. • This discovery may explain

  2. Targeting Bax interaction sites reveals that only homo-oligomerization sites are essential for its activation

    Science.gov (United States)

    Peng, R; Tong, J-S; Li, H; Yue, B; Zou, F; Yu, J; Zhang, L

    2013-01-01

    Bax is a proapoptotic Bcl-2 family member that has a central role in the initiation of mitochondria-dependent apoptosis. However, the mechanism of Bax activation during apoptosis remains unsettled. It is believed that the activation of Bax is mediated by either dissociation from prosurvival Bcl-2 family members, or direct association with BH3-only members. Several interaction sites on Bax that mediate its interactions with other Bcl-2 family members, as well as its proapoptotic activity, have been identified in previous studies by other groups. To rigorously investigate the functional role of these interaction sites, we knocked in their respective mutants using HCT116 colon cancer cells, in which apoptosis induced by several stimuli is strictly Bax-dependent. Bax-mediated apoptosis was intact upon knock-in (KI) of K21E and D33A, which were shown to block the interaction of Bax with BH3-only activators. Apoptosis was partially reduced by KI of D68R, which impairs the interaction of Bax with prosurvival members, and S184V, a constitutively mitochondria-targeting mutant. In contrast, apoptosis was largely suppressed by KI of L70A/D71A, which blocks homo-oligomerization of Bax and its binding to prosurvival Bcl-2 family proteins. Collectively, our results suggest that the activation of endogenous Bax in HCT116 cells is dependent on its homo-oligomerization sites, but not those previously shown to interact with BH3-only activators or prosurvival proteins only. We therefore postulate that critical interaction sites yet to be identified, or mechanisms other than protein-protein interactions, need to be pursued to delineate the mechanism of Bax activation during apoptosis. PMID:23392123

  3. Defining the oligomerization state of γ-synuclein in solution and in cells.

    Science.gov (United States)

    Golebiewska, Urszula; Zurawsky, Cassandra; Scarlata, Suzanne

    2014-01-21

    γ-Synuclein is expressed at high levels in neuronal cells and in multiple invasive cancers. Like its family member α-synuclein, γ-synuclein is thought to be natively unfolded but does not readily form fibrils. The function of γ-synuclein is unknown, but we have found that it interacts strongly with the enzyme phospholipase Cβ (PLCβ), altering its interaction with G proteins. As a first step in determining its role, we have characterized its oligomerization using fluorescence homotransfer, photon-counting histogram analysis, and native gel electrophoresis. We found that when its expressed in Escherichia coli and purified, γ-synuclein appears monomeric on chromatographs under denaturing conditions, but under native conditions, it appears as oligomers of varying sizes. We followed the monomer-to-tetramer association by labeling the protein with fluorescein and following the concentration-dependent loss in fluorescence anisotropy resulting from fluorescence homotransfer. We also performed photon-counting histogram analysis at increasing concentrations of fluorescein-labeled γ-synuclein and found concentration-dependent oligomerization. Addition of PLCβ2, a strong γ-synuclein binding partner whose cellular expression is correlated with γ-synuclein, results in disruption of γ-synuclein oligomers. Similarly, its binding to lipid membranes promotes the monomer form. When we exogenously express γ-synuclein or microinject purified protein into cells, the protein appears monomeric. Our studies show that even though purified γ-synuclein form oligomers, when binding partners are present, as in cells, it dissociates to a monomer to bind these partners, which in turn may modify protein function and integrity.

  4. The R439C mutation in LMNA causes lamin oligomerization and susceptibility to oxidative stress

    Science.gov (United States)

    Verstraeten, Valerie LRM; Caputo, Sandrine; Van Steensel, Maurice AM; Duband-Goulet, Isabelle; Zinn-Justin, Sophie; Kamps, Miriam; Kuijpers, Helma JH; Östlund, Cecilia; Worman, Howard J; Briedé, Jacob J; Le Dour, Caroline; Marcelis, Carlo LM; Van Geel, Michel; Steijlen, Peter M; Van Den Wijngaard, Arthur; Ramaekers, Frans CS; Broers, Jos LV

    2009-01-01

    Abstract Dunnigan-type familial partial lipodystrophy (FPLD) is a laminopathy characterized by an aberrant fat distribution and a metabolic syndrome for which oxidative stress has recently been suggested as one of the disease-causing mechanisms. In a family affected with FPLD, we identified a heterozygous missense mutation c.1315C>T in the LMNA gene leading to the p.R439C substitution. Cultured patient fibroblasts do not show any prelamin A accumulation and reveal honeycomb-like lamin A/C formations in a significant percentage of nuclei. The mutation affects a region in the C-terminal globular domain of lamins A and C, different from the FPLD-related hot spot. Here, the introduction of an extra cysteine allows for the formation of disulphide-mediated lamin A/C oligomers. This oligomerization affects the interaction properties of the C-terminal domain with DNA as shown by gel retardation assays and causes a DNA-interaction pattern that is distinct from the classical R482W FPLD mutant. Particularly, whereas the R482W mutation decreases the binding efficiency of the C-terminal domain to DNA, the R439C mutation increases it. Electron spin resonance spectroscopy studies show significantly higher levels of reactive oxygen species (ROS) upon induction of oxidative stress in R439C patient fibroblasts compared to healthy controls. This increased sensitivity to oxidative stress seems independent of the oligomerization and enhanced DNA binding typical for R439C, as both the R439C and R482W mutants show a similar and significant increase in ROS upon induction of oxidative stress by H2O2. PMID:19220582

  5. Genetic analysis and serum level of cartilage oligomeric matrix protein in patients with pseudoachondroplasia

    Institute of Scientific and Technical Information of China (English)

    LIU Feng-xia; LI Zhi-ling; WEI Zhen-ji; MENG yan; REN Cui-ai; ZHANG Xu-de; YU Meng-xue; HUANG Shang-zhi

    2010-01-01

    Background Pseudoachondroplasia (PSACH) is an autosomal-dominant osteochondrodysplasia due to mutations in the gene encoding cartilage oligomeric matrix protein (COMP).Clinical diagnosis of PSACH is based primarily on family history, physical examination, and radiographic evaluation.There is evidence that decreased serum COMP concentration may serve as a diagnostic marker in PSACH.Here, we investigated the role of this gene and the serum COMP concentration in Chinese patients with PSACH.Methods A family with three patients and a sporadic case were recruited.Genomic and phenotypic data were recorded.The diagnosis of PSACH was made on the base of clinical evaluation.The genomic DNA was extracted from peripheral blood leukocytes.The 8-19 exons and flanking intron-exon boundary sequences of COMP were amplified by polymerase chain reaction (PCR) and screened for mutation by direct DNA sequencing.Serum COMP concentrations of 4 patients and age-compatible control group of 20 unrelated healthy subjects were analyzed on the basis of an ELISA Kit for human cartilage oligomeric matrix protein.Results A deletion (c.1447-1455del) was identified in exon 13 in the sporadic case.The mean serum COMP concentrations of four patients (3.12±2.28) were significantly lower than those of control group (10.86±2.21, P <0.05).There was no overlap in the distribution of serum COMP concentration between PSACH patients and controls.Conclusions Mutations in COMP gene are responsible for the PSACH.Serum COMP concentration may be suggested as an additional diagnostic marker to aid clinical findings in suspected cases of PSACH.

  6. Following activation of the amyloid cascade, apolipoprotein E4 drives the in vivo oligomerization of amyloid-β resulting in neurodegeneration.

    Science.gov (United States)

    Belinson, Haim; Kariv-Inbal, Zehavit; Kayed, Rakez; Masliah, Eliezer; Michaelson, Daniel M

    2010-01-01

    According to the amyloid hypothesis, the accumulation of oligomerized amyloid-β (Aβ) is a primary event in the pathogenesis of Alzheimer's disease (AD). The trigger of the amyloid cascade and of Aβ oligomerization in sporadic AD, the most prevalent form of the disease, remains elusive. Here, we examined the hypothesis that apolipoprotein E4 (ApoE4), the most prevalent genetic risk factor for AD, triggers the accumulation of intraneuronal oligomerized Aβ following activation of the amyloid cascade. We investigated the intracellular organelles that are targeted by these processes and govern their pathological consequences. This revealed that activation of the amyloid cascade in vivo by inhibition of the Aβ degrading enzyme neprilysin specifically results in accumulation of Aβ and oligomerized Aβ and of ApoE4 in the CA1 neurons of ApoE4 mice. This was accompanied by lysosomal and mitochondrial pathology and the co-localization of Aβ, oligomerized Aβ, and ApoE4 with enlarged lysosomes and of Aβ and oligomerized Aβ with mitochondria. The time course of the lysosomal effects paralleled that of the loss of CA1 neurons, whereas the mitochondrial effects reached an earlier plateau. These findings suggest that ApoE4 potentiates the pathological effects of Aβ and the amyloid cascade by triggering the oligomerization of Aβ, which in turn, impairs intraneuronal mitochondria and lysosomes and drives neurodegeneration.

  7. Behavioral approaches to promoting play.

    Science.gov (United States)

    Stahmer, Aubyn C; Ingersoll, Brooke; Carter, Cynthia

    2003-12-01

    A variety of techniques grounded in behavioral psychology, and more specifically in applied behavior analysis, have been established to increase and improve play skills in children with autistic spectrum disorders. This article introduces a set of efficacious methods, which range from highly structured techniques to more naturalistic strategies. It focuses on object play as other authors in the issue discuss social play in greater depth. Behavioral techniques that are reviewed include: discrete trial training, use of stereotyped behaviors to increase play skills, pivotal response training, reciprocal imitation training, differential reinforcement of appropriate behavior, in vivo modeling and play scripts, and video modeling. A discussion of expanding behavior techniques to teach more complex play as well as training in varied environments is also presented. References are provided to allow the reader to obtain more in-depth information about each technique.

  8. Playing with the Multiple Intelligences: How Play Helps Them Grow

    Science.gov (United States)

    Eberle, Scott G.

    2011-01-01

    Howard Gardner first posited a list of "multiple intelligences" as a liberating alternative to the assumptions underlying traditional IQ testing in his widely read study "Frames of Mind" (1983). Play has appeared only in passing in Gardner's thinking about intelligence, however, even though play instructs and trains the verbal, interpersonal,…

  9. Let's Play: Teaching Play Skills to Young Children with Autism

    Science.gov (United States)

    Boutot, E. Amanda; Guenther, Tracee; Crozier, Shannon

    2005-01-01

    Watch any young child and you will likely see him or her engaged in some form of play. Play is an integral part of early childhood development in which typically developing children learn social and language skills, as well as appropriate behaviors, problem solving, and a variety of other cognitive skills. By its very definition, autism is a…

  10. PlayFit: Designing playful activity interventions for teenagers

    NARCIS (Netherlands)

    M. M. Deen; Rob Tieben; Dr. Tilde Bekker; Dr. Janienke Sturm; B.A.M. Ben Schouten

    2011-01-01

    Young people spend a large part of their day sedentary, both at school and at home. The aim of the PlayFit project is to persuade teenagers to lead a more active lifestyle by using digital as well as non-digital games and play. In this position paper, we describe in detail the three key principles o

  11. The Internet of Playful Things

    DEFF Research Database (Denmark)

    Wyeth, Peta; Brereton, Margot; Roe, Paul;

    2015-01-01

    This one-day workshop brings together researchers and practitioners to share knowledge and practices on how people can connect and interact with the Internet of Things in a playful way. Open to participants with a diverse range of interests and expertise, and by exploring novel ways to playfully...... will be a road map to support the development of a Model of Playful Connectedness, focusing on how best to design and make playful networks of things, identifying the challenges that need to be addressed in order to do so....

  12. Symbolic play and language development.

    Science.gov (United States)

    Orr, Edna; Geva, Ronny

    2015-02-01

    Symbolic play and language are known to be highly interrelated, but the developmental process involved in this relationship is not clear. Three hypothetical paths were postulated to explore how play and language drive each other: (1) direct paths, whereby initiation of basic forms in symbolic action or babbling, will be directly related to all later emerging language and motor outputs; (2) an indirect interactive path, whereby basic forms in symbolic action will be associated with more complex forms in symbolic play, as well as with babbling, and babbling mediates the relationship between symbolic play and speech; and (3) a dual path, whereby basic forms in symbolic play will be associated with basic forms of language, and complex forms of symbolic play will be associated with complex forms of language. We micro-coded 288 symbolic vignettes gathered during a yearlong prospective bi-weekly examination (N=14; from 6 to 18 months of age). Results showed that the age of initiation of single-object symbolic play correlates strongly with the age of initiation of later-emerging symbolic and vocal outputs; its frequency at initiation is correlated with frequency at initiation of babbling, later-emerging speech, and multi-object play in initiation. Results support the notion that a single-object play relates to the development of other symbolic forms via a direct relationship and an indirect relationship, rather than a dual-path hypothesis.

  13. Multispecies methods, technologies for play

    DEFF Research Database (Denmark)

    Jørgensen, Ida Kathrine Hammeleff; Wirman, Hanna

    2016-01-01

    reveals limitations of designers’ knowledge of prospected users. The article explores how to approach participants who cannot express themselves verbally and how to recognise play that may not look familiar to the designer. The article finally presents a participatory design method that allows for non......-human contributions in design. This method applies play as an interspecies co-creative act and can be used as a starting point for addressing questions of difference in play and designing games that allow for ambiguous play....

  14. Seductive play in digital games

    DEFF Research Database (Denmark)

    Jørgensen, Ida Kathrine Hammeleff

    2015-01-01

    seduction is meaningless because it is nothing but appearances – a sign without reference. In his conceptualization of seduction Baudrillard draws heavily upon Huizinga’s (1950) and Callois’ (1961) theory of play. To Baudrillard play is the mode of the seductive. But in contrast to both Callois and Huizinga...

  15. Making Play Work for Education

    Science.gov (United States)

    Weisberg, Deena Skolnick; Kittredge, Audrey K.; Hirsh-Pasek, Kathy; Golinkoff, Roberta Michnick; Klahr, David

    2015-01-01

    Children, especially in the preschool years, learn a tremendous amount through play. Research on guided play demonstrates how schools can couple a curriculum-centered preschool program with a developmentally appropriate pedagogical approach to classroom teaching. However, to fully test this claim, we need a clear definition of the term…

  16. Transmedia Play: Literacy across Media

    Science.gov (United States)

    Alper, Meryl; Herr-Stephenson, Rebecca

    2013-01-01

    Transmedia play is a new way to understand how children develop critical media literacy and new media literacies through their interactions with contemporary media that links stories and structures across platforms. This essay highlights five characteristics of transmedia play that make it particularly useful for learning:…

  17. Sand and Water Table Play

    Science.gov (United States)

    Wallace, Ann H.; White, Mary J.; Stone, Ryan

    2010-01-01

    The authors observed preschoolers engaged at the sand and water table to determine if math could be found within their play. Wanting to understand how children interact with provided materials and what kinds of math ideas they explore during these interactions, the authors offer practical examples of how such play can promote mathematical…

  18. Playful Interfaces: Introduction and History

    NARCIS (Netherlands)

    Nijholt, Anton; Nijholt, Anton

    2014-01-01

    In this short survey we have some historical notes about human-computer interface development with an emphasis on interface technology that has allowed us to design playful interactions with applications. The applications do not necessarily have to be entertainment applications. We can have playful

  19. Young Children and War Play.

    Science.gov (United States)

    Carlsson-Paige, Nancy; Levin, Diane E.

    1988-01-01

    In a recent survey of parents and early childhood professionals the prevalence of war play among children and an increase in the amount of violence in children's play was noted. Outlines how the deregulation of children's television during the Reagan administration has affected children's exposure to violence in children's television programming.…

  20. Sand and Water Table Play

    Science.gov (United States)

    Wallace, Ann H.; White, Mary J.; Stone, Ryan

    2010-01-01

    The authors observed preschoolers engaged at the sand and water table to determine if math could be found within their play. Wanting to understand how children interact with provided materials and what kinds of math ideas they explore during these interactions, the authors offer practical examples of how such play can promote mathematical…

  1. The Fractal Self at Play

    Science.gov (United States)

    Marks-Tarlow, Terry

    2010-01-01

    In this article, the author draws on contemporary science to illuminate the relationship between early play experiences, processes of self-development, and the later emergence of the fractal self. She argues that orientation within social space is a primary function of early play and developmentally a two-step process. With other people and with…

  2. The Play of Socratic Dialogue

    Science.gov (United States)

    Smith, Richard

    2011-01-01

    Proponents of philosophy for children generally see themselves as heirs to the "Socratic" tradition. They often claim too that children's aptitude for play leads them naturally to play with abstract, philosophical ideas. However in Plato's dialogues we find in the mouth of "Socrates" many warnings against philosophising with the young. Those…

  3. Empowering Groups that Enable Play

    Science.gov (United States)

    Wilson, David Sloan; Marshall, Danielle; Iserhott, Hindi

    2011-01-01

    Creating play environments for children usually requires groups of adults working together. An extensive scientific literature describes how groups function to achieve shared goals in general terms, and groups attempting to empower play may find this literature useful. Design principles for managing natural resources, identified by Elinor Ostrom…

  4. Let's Play Three on Three!

    Science.gov (United States)

    Kern, Jack; Calleja, Paul

    2008-01-01

    Over the course of nine years as a supervisor of intern teachers, the first author collected observations of game play during lessons taught by intern teachers or their mentors. In general, the observations indicated that the majority of students got limited practice opportunities during game play. A close look at the data revealed an interesting…

  5. The mitochondrial Na+/Ca2+exchanger may reduce high glucose-induced oxidative stress and nucleotide-binding oligomerization domain receptor 3 inflammasome activation in endothelial cells

    Institute of Scientific and Technical Information of China (English)

    Yuan ZU; Li-Juan WAN; Shao-Yuan CUI; Yan-Ping GONG; Chun-Lin LI

    2015-01-01

    Background The mitochondrial Na+/Ca2+exchanger, NCLX, plays an important role in the balance between Ca2+influx and efflux across the mitochondrial inner membrane in endothelial cells. Mitochondrial metabolism is likely to be affected by the activity of NCLX because Ca2+activates several enzymes of the Krebs cycle. It is currently believed that mitochondria are not only centers of energy produc-tion but are also important sites of reactive oxygen species (ROS) generation and nucleotide-binding oligomerization domain receptor 3 (NLRP3) inflammasome activation. Methods&Results This study focused on NCLX function, in rat aortic endothelial cells (RAECs), induced by glucose. First, we detected an increase in NCLX expression in the endothelia of rats with diabetes mellitus, which was induced by an injection of streptozotocin. Next, colocalization of NCLX expression and mitochondria was detected using confocal analysis. Suppression of NCLX expression, using an siRNA construct (siNCLX), enhanced mitochondrial Ca2+influx and blocked efflux induced by glucose. Un-expectedly, silencing of NCLX expression induced increased ROS generation and NLRP3 inflammasome activation. Conclusions These findings suggest that NCLX affects glucose-dependent mitochondrial Ca2+signaling, thereby regulating ROS generation and NLRP3 in-flammasome activation in high glucose conditions. In the early stages of high glucose stimulation, NCLX expression increases to compensate in order to self-protect mitochondrial maintenance, stability, and function in endothelial cells.

  6. Up-regulation of Cartilage Oligomeric Matrix Protein Gene Expression by Insulin-like Growth Factor-I Revealed by Real Time Reverse Transcription-Polymerase Chain Reaction

    Institute of Scientific and Technical Information of China (English)

    Hua TIAN; Ioannis STOGIANNIDIS

    2006-01-01

    Cartilage oligomeric matrix protein (COMP) strengthens cartilage by binding to type Ⅱ and typeⅨ collagen-forming bridges between collagen fibrils. It was hypothesized that perhaps one or more anabolic growth factors such as insulin-like growth factor-I (IGF-I), fibroblast growth factor-1 (FGF-1) or platelet derived growth factor-BB (PDGF-BB) increase COMP gene expression. Their effects on primary human chondrocytes and the chondrogenic cell line ATDC5 were studied using real time reverse transcript-polymerase chain reaction (RT-PCR) for quantification. IGF-I, but not the FGF-1 or PDGF-BB, up-regulated COMP gene expression by approximate 5-fold in human adult chondrocytes in a dose- and time-dependent manner. IGF-I exerted similar effects on ATDC5 cells. Results from these real time RT-PCR experiments were confirmed by transfecting into ATDC5 cells a full-length mouse COMP promoter cloned upstream of a luciferase reporter gene. On stimulation with IGF-I, the luciferase reporter activity increased by about eight times. In conclusion, IGF-I seems to be an important positive regulator of COMP, which may play an important role in an attempted repair of either traumatized or degenerated cartilage.

  7. On the Fair Play Spirit%论Fair Play

    Institute of Scientific and Technical Information of China (English)

    张维; 林琳

    2011-01-01

    采用文献资料法,历史分析了"Fair Play"精神的起源,并结合Fair Play精神面临的时代压力,探讨现代体育生命力延续的议题,提出"人"才是体育及其"Fair Play"精神继续生存或走向毁灭的主宰者.

  8. Playful biometrics: controversial technology through the lens of play.

    Science.gov (United States)

    Ellerbrok, Ariane

    2011-01-01

    This article considers the role of play in the context of technological emergence and expansion, particularly as it relates to recently emerging surveillance technologies. As a case study, I consider the trajectory of automated face recognition—a biometric technology of numerous applications, from its more controversial manifestations under the rubric of national security to a clearly emerging orientation toward play. This shift toward “playful” biometrics—or from a technology traditionally coded as “hard” to one now increasingly coded as “soft”—is critical insofar as it renders problematic the traditional modes of critique that have, up until this point, challenged the expansion of biometric systems into increasingly ubiquitous realms of everyday life. In response to this dynamic, I propose theorizing the expansion of face recognition specifically in relation to “play,” a step that allows us to broaden the critical space around newly emerging playful biometrics, as well as playful surveillance more generally. In addition, play may also have relevance for theorizing other forms of controversial technology, particularly given its potential role in processes of obfuscation, normalization, and marginalization.

  9. Effects of aerobic exercise intervention on serum cartilage oligomeric matrix protein levels and lymphocyte dna damage in obese elderly females

    Science.gov (United States)

    Cho, Su Youn; Roh, Hee Tae

    2016-01-01

    [Purpose] The aim of the reported research was to investigate the effects of regular aerobic exercise on cartilage oligomeric matrix protein and oxidative DNA damage in obese, elderly females. [Subjects and Methods] Sixteen class I obese, elderly females, according to World Health Organization criteria, were randomly and equally assigned to a control group (n=8) or an exercise group (n=8). The exercise group participated in exercise sessions of 60 minutes per day, 3 days per week, for a period of 8 weeks. [Results] After aerobic exercise intervention, weight, body mass index, body fat, waist circumference, and DNA damage (Tail moment) were significantly decreased, compared with baseline values. In contrast, serum cartilage oligomeric matrix protein levels were not significantly different among any groups or time-points. [Conclusion] Regular aerobic exercise may be effective for reducing obesity-induced high DNA damage levels in obese females, without causing the deformation or degradation of lower extremity articular cartilage. PMID:27390441

  10. Binding of an Oligomeric Ellagitannin Series to Bovine Serum Albumin (BSA): Analysis by Isothermal Titration Calorimetry (ITC).

    Science.gov (United States)

    Karonen, Maarit; Oraviita, Marianne; Mueller-Harvey, Irene; Salminen, Juha-Pekka; Green, Rebecca J

    2015-12-16

    A unique series of oligomeric ellagitannins was used to study their interactions with bovine serum albumin (BSA) by isothermal titration calorimetry. Oligomeric ellagitannins, ranging from monomer to heptamer and a mixture of octamer-undecamers, were isolated as individual pure compounds. This series allowed studying the effects of oligomer size and other structural features. The monomeric to trimeric ellagitannins deviated most from the overall trends. The interactions of ellagitannin oligomers from tetramers to octa-undecamers with BSA revealed strong similarities. In contrast to the equilibrium binding constant, enthalpy showed an increasing trend from the dimer to larger oligomers. It is likely that first the macrocyclic part of the ellagitannin binds to the defined binding sites on the protein surface and then the "flexible tail" of the ellagitannin coats the protein surface. The results highlight the importance of molecular flexibility to maximize binding between the ellagitannin and protein surfaces.

  11. Characterization of oligomerization of a peptide from the ebola virus glycoprotein by small-angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, V. V., E-mail: vlaegur@omrb.pnpi.spb.ru [National Research Center “Kurchatov Institute”, Konstantinov Petersburg Nuclear Physics Institute (Russian Federation); Gorshkov, A. N. [Ministry of Health of the Russian Federation, Research Institute of Influenza (Russian Federation); Murugova, T. N. [Joint Institute for Nuclear Research (Russian Federation); Vasin, A. V. [Ministry of Health of the Russian Federation, Research Institute of Influenza (Russian Federation); Lebedev, D. V.; Isaev-Ivanov, V. V. [National Research Center “Kurchatov Institute”, Konstantinov Petersburg Nuclear Physics Institute (Russian Federation); Kiselev, O. I. [Ministry of Health of the Russian Federation, Research Institute of Influenza (Russian Federation)

    2016-01-15

    Transmission electron microscopy (TEM) and small-angle neutron scattering (SANS) studies showed that model peptides QNALVCGLRQ (G33) and QNALVCGLRG (G31) corresponding to region 551–560 of the GP protein of the Sudan Ebola virus are prone to oligomerization in solution. Both peptides can form amyloid-like fibrills. The G33 peptide forms fibrils within one day of incubation, whereas the fibrillogenesis of the G31 peptide is observed only after incubation for several months. The possible role of the observed processes in the pathogenesis and the possibility of applying a combination of the TEM and SANS techniques to search for new compounds that are able to influence the protein oligomerization are discussed.

  12. Bax monomers form dimer units in the membrane that further self-assemble into multiple oligomeric species

    Science.gov (United States)

    Subburaj, Yamunadevi; Cosentino, Katia; Axmann, Markus; Pedrueza-Villalmanzo, Esteban; Hermann, Eduard; Bleicken, Stephanie; Spatz, Joachim; García-Sáez, Ana J.

    2015-08-01

    Bax is a key regulator of apoptosis that mediates the release of cytochrome c to the cytosol via oligomerization in the outer mitochondrial membrane before pore formation. However, the molecular mechanism of Bax assembly and regulation by other Bcl-2 members remains obscure. Here, by analysing the stoichiometry of Bax oligomers at the single-molecule level, we find that Bax binds to the membrane in a monomeric state and then self-assembles in Bax does not exist in a unique oligomeric state, but as several different species based on dimer units. Moreover, we show that cBid activates Bax without affecting its assembly, while Bcl-xL induces the dissociation of Bax oligomers. On the basis of our experimental data and theoretical modelling, we propose a new mechanism for the molecular pathway of Bax assembly to form the apoptotic pore.

  13. Characterization of oligomerization of a peptide from the ebola virus glycoprotein by small-angle neutron scattering

    Science.gov (United States)

    Egorov, V. V.; Gorshkov, A. N.; Murugova, T. N.; Vasin, A. V.; Lebedev, D. V.; Isaev-Ivanov, V. V.; Kiselev, O. I.

    2016-01-01

    Transmission electron microscopy (TEM) and small-angle neutron scattering (SANS) studies showed that model peptides QNALVCGLRQ (G33) and QNALVCGLRG (G31) corresponding to region 551-560 of the GP protein of the Sudan Ebola virus are prone to oligomerization in solution. Both peptides can form amyloid-like fibrills. The G33 peptide forms fibrils within one day of incubation, whereas the fibrillogenesis of the G31 peptide is observed only after incubation for several months. The possible role of the observed processes in the pathogenesis and the possibility of applying a combination of the TEM and SANS techniques to search for new compounds that are able to influence the protein oligomerization are discussed.

  14. Oligomerization and Polymerization of Ethylene Initiated by a Novel Ni(Ⅱ)-Based Acetyliminopyridine Complexes as Single-Site Catalysts

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Novel Ni(Ⅱ)-based acetyliminopyridine complexes 1b, 2b, 3b (1-3b), which are synthesized from ligands 1a, 2a, 3a (1-3a) and [NiCl2(DME)], are suitable precursors for the catalysts that are necessary for ethylene oligomerization and polymerization reactions, activated by methylaluminoxane (MAO).The MAO-treated 1-3b presents an active catalytic center, which may oligomerize and polymerize ethylene to produce linear α-olefins and polyethylene, respectively. The molecular weight distributions of oligomers that are obtained are in good agreement with the Schulz-Flory rules for oligomers>C4. The activity of oligomers show significant reliance on the structures of catalyst precursors.

  15. Synthesis, Characterization and Ethylene Oligomerization Behavior of Neutral Nickel Complexes Bearing N-Fluorinated Phenyl Salicylaldiminato Chelate Ligands

    Institute of Scientific and Technical Information of China (English)

    宋力平; 宋绍迪; 黄吉玲

    2012-01-01

    A series of neutral nickel complexes featuring N-fluorinated phenyl salicylaldiminato chelate ligands was syn- thesized, and the novel molecular structure of complex C14 was further confirmed by X-ray crystallographic analy- sis. The neutral nickel complexes showed high activity up to 9.96× 10^5 g oligomers/(mol Nioh) and high selectivity of C6 in catalyzing ethylene oligomerization using methylaluminoxane (MAO) as cocatalyst. It was observed that the strong electron-withdrawing effect of the fluorinated salicylaldiminato ligand was able to significantly increase the catalytic activity for oligomerization of ethylene. In addition, the influence of reaction parameters such as A1/Ni molar ratio, reaction temperature, a variety of cocatalyst and ethylene pressure on catalytic activity was investigated.

  16. Moyamoya disease-associated protein mysterin/RNF213 is a novel AAA+ ATPase, which dynamically changes its oligomeric state

    Science.gov (United States)

    Morito, Daisuke; Nishikawa, Kouki; Hoseki, Jun; Kitamura, Akira; Kotani, Yuri; Kiso, Kazumi; Kinjo, Masataka; Fujiyoshi, Yoshinori; Nagata, Kazuhiro

    2014-03-01

    Moyamoya disease is an idiopathic human cerebrovascular disorder that is characterized by progressive stenosis and abnormal collateral vessels. We recently identified mysterin/RNF213 as its first susceptibility gene, which encodes a 591-kDa protein containing enzymatically active P-loop ATPase and ubiquitin ligase domains and is involved in proper vascular development in zebrafish. Here we demonstrate that mysterin further contains two tandem AAA+ ATPase modules and forms huge ring-shaped oligomeric complex. AAA+ ATPases are known to generally mediate various biophysical and mechanical processes with the characteristic ring-shaped structure. Fluorescence correlation spectroscopy and biochemical evaluation suggested that mysterin dynamically changes its oligomeric forms through ATP/ADP binding and hydrolysis cycles. Thus, the moyamoya disease-associated gene product is a unique protein that functions as ubiquitin ligase and AAA+ ATPase, which possibly contributes to vascular development through mechanical processes in the cell.

  17. A multiverse play divides opinion

    Science.gov (United States)

    Crease, Robert P.

    2015-03-01

    The stage lights rise. A man and woman meet in a cute way - "Do you know why it's impossible to lick the tips of your elbows?" she asks - they chat momentarily, and separate. The play is Constellations by Nick Payne.

  18. Play the Blood Typing Game

    Science.gov (United States)

    ... Nobel's Life and Work Teachers' Questionnaire The Blood Typing Game What happens if you get a blood ... learn about human blood types! Play the Blood Typing Game About this game Embed the Blood Typing ...

  19. Discussion of "interpretation and play".

    Science.gov (United States)

    Pick, Irma Brenman

    2011-01-01

    This discussion addresses the conflict in technique between play versus interpretation. It further considers how the nature of the interpretation may be affected by a consideration of what is being projected into the analyst.

  20. THE VALUE OF ROLE PLAY

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    IntroductionIn China,the English as a foreign language (EFL) class for non-English majors at college levelprovides little opportunity for oral interaction among students.One solution to this problem is toadopt a series of communicative teaching techniques.Role play is one such technique.This paperattempts to assess the value of role play by analysing our experience of using it as a communicationactivity.

  1. Digital Play: A New Classification

    Science.gov (United States)

    Marsh, Jackie; Plowman, Lydia; Yamada-Rice, Dylan; Bishop, Julia; Scott, Fiona

    2016-01-01

    This paper draws on an ESRC-funded study of play and creativity in preschool-aged children's use of apps in the UK. The main objectives of the study were to collect information about access to and use of apps in the home, establish the most popular apps and identify the features of those apps that are successful in promoting play and creativity. A…

  2. Increased serum cartilage oligomeric matrix protein levels and decreased patellar bone mineral density in patients with chondromalacia patellae.

    OpenAIRE

    2002-01-01

    BACKGROUND: Chondromalacia patellae is a potentially disabling disorder characterised by features of patellar cartilage degradation. OBJECTIVE: To evaluate markers of cartilage and bone turnover in patients with chondromalacia patellae. METHODS: 18 patients with chondromalacia patellae were studied. Serum cartilage oligomeric matrix protein (s-COMP) and bone sialoprotein (s-BSP) levels were measured by enzyme linked immunosorbent assay (ELISA) and compared with those of age and sex matched he...

  3. Atmospheric protein chemistry influenced by anthropogenic air pollutants: nitration and oligomerization upon exposure to ozone and nitrogen dioxide.

    Science.gov (United States)

    Liu, Fobang; Lakey, Pascale S J; Berkemeier, Thomas; Tong, Haijie; Kunert, Anna Theresa; Meusel, Hannah; Cheng, Yafang; Su, Hang; Fröhlich-Nowoisky, Janine; Lai, Senchao; Weller, Michael G; Shiraiwa, Manabu; Pöschl, Ulrich; Kampf, Christopher J

    2017-08-24

    The allergenic potential of airborne proteins may be enhanced via post-translational modification induced by air pollutants like ozone (O3) and nitrogen dioxide (NO2). The molecular mechanisms and kinetics of the chemical modifications that enhance the allergenicity of proteins, however, are still not fully understood. Here, protein tyrosine nitration and oligomerization upon simultaneous exposure of O3 and NO2 were studied in coated-wall flow-tube and bulk solution experiments under varying atmospherically relevant conditions (5-200 ppb O3, 5-200 ppb NO2, 45-96% RH), using bovine serum albumin as a model protein. Generally, more tyrosine residues were found to react via the nitration pathway than via the oligomerization pathway. Depending on reaction conditions, oligomer mass fractions and nitration degrees were in the ranges of 2.5-25% and 0.5-7%, respectively. The experimental results were well reproduced by the kinetic multilayer model of aerosol surface and bulk chemistry (KM-SUB). The extent of nitration and oligomerization strongly depends on relative humidity (RH) due to moisture-induced phase transition of proteins, highlighting the importance of cloud processing conditions for accelerated protein chemistry. Dimeric and nitrated species were major products in the liquid phase, while protein oligomerization was observed to a greater extent for the solid and semi-solid phase states of proteins. Our results show that the rate of both processes was sensitive towards ambient ozone concentration, but rather insensitive towards different NO2 levels. An increase of tropospheric ozone concentrations in the Anthropocene may thus promote pro-allergic protein modifications and contribute to the observed increase of allergies over the past decades.

  4. Protective role of Cys-178 against the inactivation and oligomerization of human insulin-degrading enzyme by oxidation and nitrosylation.

    Science.gov (United States)

    Ralat, Luis A; Ren, Min; Schilling, Alexander B; Tang, Wei-Jen

    2009-12-01

    Insulin-degrading enzyme (IDE), a 110-kDa metalloendopeptidase, hydrolyzes several physiologically relevant peptides, including insulin and amyloid-beta (Abeta). Human IDE has 13 cysteines and is inhibited by hydrogen peroxide and S-nitrosoglutathione (GSNO), donors of reactive oxygen and nitrogen species, respectively. Here, we report that the oxidative burst of BV-2 microglial cells leads to oxidation or nitrosylation of secreted IDE, leading to the reduced activity. Hydrogen peroxide and GSNO treatment of IDE reduces the V(max) for Abeta degradation, increases IDE oligomerization, and decreases IDE thermostability. Additionally, this inhibitory response of IDE is substrate-dependent, biphasic for Abeta degradation but monophasic for a shorter bradykinin-mimetic substrate. Our mutational analysis of IDE and peptide mass fingerprinting of GSNO-treated IDE using Fourier transform-ion cyclotron resonance mass spectrometer reveal a surprising interplay of Cys-178 with Cys-110 and Cys-819 for catalytic activity and with Cys-789 and Cys-966 for oligomerization. Cys-110 is near the zinc-binding catalytic center and is normally buried. The oxidation and nitrosylation of Cys-819 allow Cys-110 to be oxidized or nitrosylated, leading to complete inactivation of IDE. Cys-789 is spatially adjacent to Cys-966, and their nitrosylation and oxidation together trigger the oligomerization and inhibition of IDE. Interestingly, the Cys-178 modification buffers the inhibition caused by Cys-819 modification and prevents the oxidation or nitrosylation of Cys-110. The Cys-178 modification can also prevent the oligomerization-mediated inhibition. Thus, IDE can be intricately regulated by reactive oxygen or nitrogen species. The structure of IDE reveals the molecular basis for the long distance interactions of these cysteines and how they regulate IDE function.

  5. Screening of drugs inhibiting in vitro oligomerization of Cu/Zn-superoxide dismutase with a mutation causing amyotrophic lateral sclerosis

    OpenAIRE

    Itsuki Anzai; Keisuke Toichi; Eiichi Tokuda; Atsushi Mukaiyama; Shuji Akiyama; Yoshiaki Furukawa

    2016-01-01

    Dominant mutations in Cu/Zn-superoxide dismutase (SOD1) gene have been shown to cause a familial form of amyotrophic lateral sclerosis (SOD1-ALS). A major pathological hallmark of this disease is abnormal accumulation of mutant SOD1 oligomers in the affected spinal motor neurons. While no effective therapeutics for SOD1-ALS is currently available, SOD1 oligomerization will be a good target for developing cures of this disease. Recently, we have reproduced the formation of SOD1 oligomers ab...

  6. Synthesis, Characterization of Neutral Nickel Complexes Bearing N-Fluorophenylsalicylaldimine Chelate Ligands and Their Catalytic Activity to Ethylene Oligomerization

    Institute of Scientific and Technical Information of China (English)

    赵蔚; 黄吉玲; 朱仕正

    2005-01-01

    A series of neutral nickel complexes featuring N-fluorophenylsalicylaldimine chelate ligands was synthesized,and the molecular structure of complex 4 was further confirmed by X-ray crystallographic analysis. The neutral nickel complexes showed high activity up to 4.22×105 g oligomers/(mol Nioh) and high selectivity to C6 olefins in catalyzing ethylene oligomerization using methylaluminoxane (MAO) as cocatalyst.

  7. Transmembrane oligomeric form of Vibrio cholerae cytolysin triggers TLR2/TLR6-dependent proinflammatory responses in monocytes and macrophages.

    Science.gov (United States)

    Khilwani, Barkha; Mukhopadhaya, Arunika; Chattopadhyay, Kausik

    2015-02-15

    Vibrio cholerae cytolysin (VCC) kills target eukaryotic cells by forming transmembrane oligomeric β-barrel pores. Once irreversibly converted into the transmembrane oligomeric form, VCC acquires an unusual structural stability and loses its cytotoxic property. It is therefore possible that, on exertion of its cytotoxic activity, the oligomeric form of VCC retained in the disintegrated membrane fractions of the lysed cells would survive within the host cellular milieu for a long period, without causing any further cytotoxicity. Under such circumstances, VCC oligomers may potentially be recognized by the host immune cells. Based on such a hypothesis, in the present study we explored the interaction of the transmembrane oligomeric form of VCC with the monocytes and macrophages of the innate immune system. Our study shows that the VCC oligomers assembled in the liposome membranes elicit potent proinflammatory responses in monocytes and macrophages, via stimulation of the toll-like receptor (TLR)2/TLR6-dependent signalling cascades that involve myeloid differentiation factor 88 (MyD88)/interleukin-1-receptor-associated kinase (IRAK)1/tumour-necrosis-factor-receptor-associated factor (TRAF)6. VCC oligomer-mediated proinflammatory responses critically depend on the activation of the transcription factor nuclear factor-κB. Proinflammatory responses induced by the VCC oligomers also require activation of the mitogen-activated protein kinase (MAPK) family member c-Jun N-terminal kinase, which presumably acts via stimulation of the transcription factor activator protein-1. Notably, the role of the MAPK p38 could not be documented in the process.

  8. Both Ca2+ and Zn2+ are essential for S100A12 protein oligomerization and function

    Directory of Open Access Journals (Sweden)

    Shekhtman Alexander

    2009-04-01

    Full Text Available Abstract Background Human S100A12 is a member of the S100 family of EF-hand calcium-modulated proteins that are associated with many diseases including cancer, chronic inflammation and neurological disorders. S100A12 is an important factor in host/parasite defenses and in the inflammatory response. Like several other S100 proteins, it binds zinc and copper in addition to calcium. Mechanisms of zinc regulation have been proposed for a number of S100 proteins e.g. S100B, S100A2, S100A7, S100A8/9. The interaction of S100 proteins with their targets is strongly dependent on cellular microenvironment. Results The aim of the study was to explore the factors that influence S100A12 oligomerization and target interaction. A comprehensive series of biochemical and biophysical experiments indicated that changes in the concentration of calcium and zinc led to changes in the oligomeric state of S100A12. Surface plasmon resonance confirmed that the presence of both calcium and zinc is essential for the interaction of S100A12 with one of its extracellular targets, RAGE – the Receptor for Advanced Glycation End products. By using a single-molecule approach we have shown that the presence of zinc in tissue culture medium favors both the oligomerization of exogenous S100A12 protein and its interaction with targets on the cell surface. Conclusion We have shown that oligomerization and target recognition by S100A12 is regulated by both zinc and calcium. Our present work highlighted the potential role of calcium-binding S100 proteins in zinc metabolism and, in particular, the role of S100A12 in the cross talk between zinc and calcium in cell signaling.

  9. Increased serum cartilage oligomeric matrix protein levels and decreased patellar bone mineral density in patients with chondromalacia patellae.

    OpenAIRE

    Murphy, E; Fitzgerald, O; Saxne, Tore; Bresnihan, B

    2002-01-01

    BACKGROUND: Chondromalacia patellae is a potentially disabling disorder characterised by features of patellar cartilage degradation. OBJECTIVE: To evaluate markers of cartilage and bone turnover in patients with chondromalacia patellae. METHODS: 18 patients with chondromalacia patellae were studied. Serum cartilage oligomeric matrix protein (s-COMP) and bone sialoprotein (s-BSP) levels were measured by enzyme linked immunosorbent assay (ELISA) and compared with those of age and sex matched he...

  10. Synthesis and Catalytic Performances of a Novel Zn-MOF Catalyst Bearing Nickel Chelating Diimine Carboxylate Ligands for Ethylene Oligomerization

    Directory of Open Access Journals (Sweden)

    Suyan Liu

    2015-01-01

    Full Text Available A novel Zn-MOF[Zn3(OH2L2] was synthesized from dicarboxylate ligands with diimine groups (1,4-bis(4-CO2HC6H4-2,3-dimethyl-1,4-diazabutadiene. The physicochemical properties of the material were characterized by a series of technologies including XRD, SEM, and ICP. In order to adapt to the ethylene oligomerization process, a catalyst [Zn3OH2L1Ni2] (denoted as Cat.A possessing active Ni2+ centers was prepared by a postsynthetic treatment method using dichloride nickel as a nickel source in this work. For comparison, α-diimine ligands with/without dicarboxylic acid groups reacted with dichloride nickel to obtain homogenous Cat.B and Cat.C, respectively. The effects of reaction parameters, including n(Al/n(Ni, temperature, and pressure on the oligomerization activities and oligomers distribution were investigated. The results demonstrated that all of catalysts used with diethylaluminum chloride were active for the ethylene oligomerization. Among them, Cat.A and Cat.B showed higher catalytic activities and higher selectivities to low-carbon α-olefins at atmospheric pressure. The Cat.A exhibited the optimal catalytic activity [6.7 × 105 g/(mol·Ni·h·atm] for C4 (91.8% under the conditions of Al/Ni = 1500, P = 1.0 atm, T = 20°C. In addition, Cat.A and Cat.B presented large amount of ethylene polymer, while Cat.C had a higher catalytic activity of ethylene oligomerization at high pressure.

  11. Oligomeric adiponectin forms and their complexes in the blood of healthy donors and patients with type 2 diabetes mellitus.

    Science.gov (United States)

    Kogan, Alexander E; Filatov, Vladimir L; Kolosova, Olga V; Katrukha, Ivan A; Mironova, Ekaterina V; Zhuravleva, Natalya S; Nagibin, Oleg A; Kara, Andrei N; Bereznikova, Anastasiya V; Katrukha, Alexey G

    2013-01-01

    Adiponectin (Adn) is a protein that circulates in the blood in several oligomeric forms, namely low-, medium-, and high-molecular-weight forms. Adn may serve as a risk factor for type 2 diabetes mellitus (T2DM). The aims of this work were (1) to produce monoclonal antibodies (MAbs) specific to different Adn oligomeric forms, (2) to design immunoassays suitable for measuring the Adn forms present in human blood, and (3) to investigate the changes in Adn forms that occur in patients with T2DM. Gel filtration, fluoroimmunoassays, and Western blotting were utilized as major techniques in this study. MAbs recognizing various oligomeric forms of Adn were obtained. Complexes between Adn and complement component C1q and between the low molecular weight form of Adn and albumin were described in human blood. A decrease in the total Adn and Adn-albumin complex levels in the blood of patients with T2DM and no difference in the levels of the Adn-C1q complex in comparison with healthy volunteers were demonstrated. An Adn94-Adn63 fluoroimmunoassay was selected as the technique that most accurately measured the mass ratio of Adn oligomers in blood samples, and an Adn214-Adn27 assay that measured the low-molecular-weight form of Adn only.

  12. Understanding Peptide Oligomeric State in Langmuir Monolayers of Amphiphilic 3-Helix Bundle-Forming Peptide-PEG Conjugates

    Science.gov (United States)

    Shu, Jessica Y.; Xu, Ting

    2016-01-01

    Coiled-coil peptide–polymer conjugates are an emerging class of biomaterials. Fundamental understanding of the coiled-coil oligomeric state and assembly process of these hybrid building blocks is necessary to exert control over their assembly into well-defined structures. Here, we studied the effect of peptide structure and PEGylation on the self-assembly process and oligomeric state of a Langmuir monolayer of amphiphilic coiled-coil peptide–polymer conjugates using X-ray reflectivity (XR) and grazing-incidence X-ray diffraction (GIXD). Our results show that the oligomeric state of PEGylated amphiphiles based on 3-helix bundle-forming peptide is surface pressure dependent, a mixture of dimers and trimers was formed at intermediate surface pressure but transitions into trimers completely upon increasing surface pressure. Moreover, the interhelical distance within the coiled-coil bundle of 3-helix peptide-PEG conjugate amphiphiles was not perturbed under high surface pressure. Present studies provide valuable insights into the self-assembly process of hybrid peptide–polymer conjugates and guidance to develop biomaterials with controlled multivalency of ligand presentation. PMID:27784156

  13. Metal-dependent SpoIIE oligomerization stabilizes FtsZ during asymmetric division in Bacillus subtilis

    Science.gov (United States)

    Król, Ewa; de Sousa Borges, Anabela; Kopacz, Malgorzata

    2017-01-01

    SpoIIE is a bifunctional protein involved in asymmetric septum formation and in activation of the forespore compartment-specific transcription factor σF through dephosphorylation of SpoIIAA-P. The phosphatase activity of SpoIIE requires Mn2+ as a metal cofactor. Here, we show that the presence of a metal cofactor also influences SpoIIE oligomerization and asymmetric septum formation. Absence of Mn2+ from sporulation medium results in a delay of the formation of polar FtsZ-rings, similar to a spoIIE null mutant. We purified the entire cytoplasmic part of the SpoIIE protein, and show that the protein copurifies with bound metals. Metal binding both stimulates SpoIIE oligomerization, and results in the formation of larger oligomeric structures. The presence of SpoIIE oligomers reduces FtsZ GTP hydrolysis activity and stabilizes FtsZ polymers in a light scattering assay. Combined, these results indicate that metal binding is not just required for SpoIIE phosphatase activity but also is important for SpoIIE's role in asymmetric septum formation. PMID:28358838

  14. Play and Space - Towards a Formal Definition of Play

    DEFF Research Database (Denmark)

    Larsen, Lasse Juel

    2015-01-01

    The aim of this article is to present a formal definition of the aspect of play generally known as ‘make-believe’. ‘Make-believe’ is defined in relation to theory of place and Dasein’s being- in-the-world as presented by Martin Heidegger in Being and time. From this point of view ‘make-believe’ can...... be defined as a uniform and situational spatial dyad where being is doubled, characterized by the presence of the physically absent. I will apply this definition after a survey of central and influential aspects of the history of the theory of play to demonstrate its relevance for a formal definition of play....

  15. Structure-properties relationships of polyhedral oligomeric silsesquioxane (POSS filled PS nanocomposites

    Directory of Open Access Journals (Sweden)

    J. J. Schwab

    2012-07-01

    Full Text Available The polyhedral oligomeric silsesquioxane (POSS additivated polystyrene (PS based nanocomposites were prepared by melt processing and the structure-properties relationships of the POSS-PS systems were compared to those of the neat PS. In order to investigate the effect of these structural parameters on the final properties of the polymer nanocomposites, five different kinds of POSS samples were used, in particular, POSS with different inorganic cage and with different organic pendent groups. The rheological investigation suggests clearly that the POSS acts as a plasticizer and that the processability of the PS was positively modified. The affinity between the POSS samples and the PS matrix was estimated by the calculated theoretical solubility parameters, considering the Hoy’s method and by morphology analysis. Minor difference between the solubility parameter of POSS and the matrix means better compatibility and no aggregation tendency. Furthermore, the POSS loading leads to a decrease of the rigidity, of the glass transition temperature and of the damping factor of the nanocomposite systems. The loading of different POSS molecules with open cage leads to a more pronounced effect on all the investigated properties that the loading of the POSS molecules with closed cage. Moreover, the melt properties are significantly influenced by the type of inorganic framework, by the type of the pendent organic groups and by the interaction between the POSS organic groups and the host matrix, while, the solid state properties appears to be influenced more by the kind of cage.

  16. Microwave dielectric study of an oligomeric electrolyte gelator by time domain reflectometry.

    Science.gov (United States)

    Kundu, Shyamal Kumar; Yagihara, Shin; Yoshida, Masaru; Shibayama, Mitsuhiro

    2009-07-30

    The dynamics of water molecules in aqueous solutions of an oligomeric electrolyte gelator, poly[pyridinium-1,4-diyliminocarbonyl-1,4-phenylene-methylene chloride] (1-Cl) was characterized by microwave dielectric measurements using the time domain reflectometry method. The dielectric dispersion and absorption curves related to the orientational motion of water molecules were described by the Cole-Cole equation. Discontinuities were observed in the concentration dependence of the dielectric relaxation strength, Deltaepsilonh, as well as in the Cole-Cole parameter, betah. These discontinuities were observed between the samples with concentrations of 6 and 7 g/L 1-Cl/water, which correspond to a change in the transparency. Such a discontinuity corresponds to the observation of the critical concentration of gelation. The interaction between water and 1-Cl molecules was discussed from the tauh-betah diagram. As 1-Cl carries an amide group, it could be expected that 1-Cl may interact hydrophilically with water, but the present result suggests that 1-Cl interact hydrophobically with water.

  17. Design of a minimal protein oligomerization domain by a structural approach.

    Science.gov (United States)

    Burkhard, P; Meier, M; Lustig, A

    2000-12-01

    Because of the simplicity and regularity of the alpha-helical coiled coil relative to other structural motifs, it can be conveniently used to clarify the molecular interactions responsible for protein folding and stability. Here we describe the de novo design and characterization of a two heptad-repeat peptide stabilized by a complex network of inter- and intrahelical salt bridges. Circular dichroism spectroscopy and analytical ultracentrifugation show that this peptide is highly alpha-helical and 100% dimeric tinder physiological buffer conditions. Interestingly, the peptide was shown to switch its oligomerization state from a dimer to a trimer upon increasing ionic strength. The correctness of the rational design principles used here is supported by details of the atomic structure of the peptide deduced from X-ray crystallography. The structure of the peptide shows that it is not a molten globule but assumes a unique, native-like conformation. This de novo peptide thus represents an attractive model system for the design of a molecular recognition system.

  18. Core-6 fucose and the oligomerization of the 1918 pandemic influenza viral neuraminidase.

    Science.gov (United States)

    Wu, Zhengliang L; Zhou, Hui; Ethen, Cheryl M; N Reinhold, Vernon

    2016-04-29

    The 1918 H1N1 influenza virus was responsible for one of the most deadly pandemics in human history. Yet to date, the structure component responsible for its virulence is still a mystery. In order to search for such a component, the neuraminidase (NA) antigen of the virus was expressed, which led to the discovery of an active form (tetramer) and an inactive form (dimer and monomer) of the protein due to different glycosylation. In this report, the N-glycans from both forms were released and characterized by mass spectrometry. It was found that the glycans from the active form had 26% core-6 fucosylated, while the glycans from the inactive form had 82% core-6 fucosylated. Even more surprisingly, the stalk region of the active form was almost completely devoid of core-6-linked fucose. These findings were further supported by the results obtained from in vitro incorporation of azido fucose and (3)H-labeled fucose using core-6 fucosyltransferase, FUT8. In addition, the incorporation of fucose did not change the enzymatic activity of the active form, implying that core-6 fucose is not directly involved in the enzymatic activity. It is postulated that core-6 fucose prohibits the oligomerization and subsequent activation of the enzyme.

  19. Oligomeric synthesis and density functional theory of leucoemeraldine base form of polyaniline

    Science.gov (United States)

    Ullah, Rizwan; Ullah, Habib; Shah, Anwar-ul-Haq Ali; Bilal, Salma; Ali, Khurshid

    2017-01-01

    Oligomeric synthesis of phenyl-end-capped oligoaniline (4PANI LB) has been carried out through a weak oxidizing agent, CuCl2, using chemical oxidative polymerization protocol. The sample was characterized by mass spectrometry, UV-vis, IR, and CHN elemental analysis. The experimental results are counterchecked with the aid of Quantum mechanical calculations such as density functional theory (DFT). DFT at B3LYP/6-31 G (d) level of theory was used for the geometric and electronic properties simulations which also confirm the existence of 4PANI LB. Excellent correlation is observed between the experiment and theory, particularly in the UV-vis spectra which conclude the formation of tetramer (fully reduced form) 4PANI LB (C24H20.06N4.07). Electronic properties such as Ionization Potential (I.P), Electron Affinities (E.A), the coefficient of highest occupied molecular orbital (HOMO), the coefficient of lowest unoccupied molecular orbital (LUMO) of 4PANI LB were evaluated at the above-mentioned level of theory.

  20. Determination of GLUT1 Oligomerization Parameters using Bioluminescent Förster Resonance Energy Transfer.

    Science.gov (United States)

    Looyenga, Brendan; VanOpstall, Calvin; Lee, Zion; Bell, Jed; Lodge, Evans; Wrobel, Katherine; Arnoys, Eric; Louters, Larry

    2016-06-30

    The facilitated glucose transporter GLUT1 (SLC2A1) is an important mediator of glucose homeostasis in humans. Though it is found in most cell types to some extent, the level of GLUT1 expression across different cell types can vary dramatically. Prior studies in erythrocytes-which express particularly high levels of GLUT1-have suggested that GLUT1 is able to form tetrameric complexes with enhanced transport activity. Whether dynamic aggregation of GLUT1 also occurs in cell types with more modest expression of GLUT1, however, is unclear. To address this question, we developed a genetically encoded bioluminescent Förster resonance energy transfer (BRET) assay using the luminescent donor Nanoluciferase and fluorescent acceptor mCherry. By tethering these proteins to the N-terminus of GLUT1 and performing saturation BRET analysis, we were able to demonstrate the formation of multimeric complexes in live cells. Parallel use of flow cytometry and immunoblotting further enabled us to estimate the density of GLUT1 proteins required for spontaneous oligomerization. These data provide new insights into the physiological relevance of GLUT1 multimerization as well as a new variant of BRET assay that is useful for measuring the interactions among other cell membrane proteins in live cells.

  1. Oncogenic Mutations Differentially Affect Bax Monomer, Dimer, and Oligomeric Pore Formation in the Membrane

    Science.gov (United States)

    Zhang, Mingzhen; Zheng, Jie; Nussinov, Ruth; Ma, Buyong

    2016-09-01

    Dysfunction of Bax, a pro-apoptotic regulator of cellular metabolism is implicated in neurodegenerative diseases and cancer. We have constructed the first atomistic models of the Bax oligomeric pore consisting with experimental residue-residue distances. The models are stable, capturing well double electron-electron resonance (DEER) spectroscopy measurements and provide structural details in line with the DEER data. Comparison with the latest experimental results revealed that our models agree well with both Bax and Bak pores, pointed to a converged structural arrangement for Bax and Bak pore formation. Using multi-scale molecular dynamics simulations, we probed mutational effects on Bax transformation from monomer → dimer → membrane pore formation at atomic resolution. We observe that two cancer-related mutations, G40E and S118I, allosterically destabilize the monomer and stabilize an off-pathway swapped dimer, preventing productive pore formation. This observation suggests a mechanism whereby the mutations may work mainly by over-stabilizing the monomer → dimer transformation toward an unproductive off-pathway swapped-dimer state. Our observations point to misfolded Bax states, shedding light on the molecular mechanism of Bax mutation-elicited cancer. Most importantly, the structure of the Bax pore facilitates future study of releases cytochrome C in atomic detail.

  2. Structure–property relationships in hybrid dental nanocomposite resins containing monofunctional and multifunctional polyhedral oligomeric silsesquioxanes

    Science.gov (United States)

    Wang, Weiguo; Sun, Xiang; Huang, Li; Gao, Yu; Ban, Jinghao; Shen, Lijuan; Chen, Jihua

    2014-01-01

    Organic-inorganic hybrid materials, such as polyhedral oligomeric silsesquioxanes (POSS), have the potential to improve the mechanical properties of the methacrylate-based composites and resins used in dentistry. In this article, nanocomposites of methacryl isobutyl POSS (MI-POSS [bears only one methacrylate functional group]) and methacryl POSS (MA-POSS [bears eight methacrylate functional groups]) were investigated to determine the effect of structures on the properties of dental resin. The structures of the POSS-containing networks were determined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Monofunctional POSS showed a strong tendency toward aggregation and crystallization, while multifunctional POSS showed higher miscibility with the dimethacrylate monomer. The mechanical properties and wear resistance decreased with increasing amounts of MI-POSS, indicating that the MI-POSS agglomerates act as the mechanical weak point in the dental resins. The addition of small amounts of MA-POSS improved the mechanical and shrinkage properties. However, samples with a higher MA-POSS concentration showed lower flexural strength and flexural modulus, indicating that there is a limited range in which the reinforcement properties of MA-POSS can operate. This concentration dependence is attributed to phase separation at higher concentrations of POSS, which affects the structural integrity, and thus, the mechanical and shrinkage properties of the dental resin. Our results show that resin with 3% MA-POSS is a potential candidate for resin-based dental materials. PMID:24550674

  3. Structure-property relationships in hybrid dental nanocomposite resins containing monofunctional and multifunctional polyhedral oligomeric silsesquioxanes.

    Science.gov (United States)

    Wang, Weiguo; Sun, Xiang; Huang, Li; Gao, Yu; Ban, Jinghao; Shen, Lijuan; Chen, Jihua

    2014-01-01

    Organic-inorganic hybrid materials, such as polyhedral oligomeric silsesquioxanes (POSS), have the potential to improve the mechanical properties of the methacrylate-based composites and resins used in dentistry. In this article, nanocomposites of methacryl isobutyl POSS (MI-POSS [bears only one methacrylate functional group]) and methacryl POSS (MA-POSS [bears eight methacrylate functional groups]) were investigated to determine the effect of structures on the properties of dental resin. The structures of the POSS-containing networks were determined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Monofunctional POSS showed a strong tendency toward aggregation and crystallization, while multifunctional POSS showed higher miscibility with the dimethacrylate monomer. The mechanical properties and wear resistance decreased with increasing amounts of MI-POSS, indicating that the MI-POSS agglomerates act as the mechanical weak point in the dental resins. The addition of small amounts of MA-POSS improved the mechanical and shrinkage properties. However, samples with a higher MA-POSS concentration showed lower flexural strength and flexural modulus, indicating that there is a limited range in which the reinforcement properties of MA-POSS can operate. This concentration dependence is attributed to phase separation at higher concentrations of POSS, which affects the structural integrity, and thus, the mechanical and shrinkage properties of the dental resin. Our results show that resin with 3% MA-POSS is a potential candidate for resin-based dental materials.

  4. Role of redox environment on the oligomerization of higher molecular weight adiponectin

    Directory of Open Access Journals (Sweden)

    Nuñez Martha

    2011-05-01

    Full Text Available Abstract Background Adiponectin is an adipocyte-secreted hormone with insulin-sensitizing and anti-inflammatory actions. The assembly of trimeric, hexameric, and higher molecular weight (HMW species of adiponectin is a topic of significant interest because physiological actions of adiponectin are oligomer-specific. In addition, adiponectin assembly is an example of oxidative oligomerization of multi-subunit protein complexes in endoplasmic reticulum (ER. Results We previously reported that trimers assemble into HMW adiponectin via intermediates stabilized by disulfide bonds, and complete oxidation of available cysteines locks adiponectin in hexameric conformation. In this study, we examined the effects of redox environment on the rate of oligomer formation and the distribution of oligomers. Reassembly of adiponectin under oxidizing conditions accelerated disulfide bonding but favored formation of hexamers over the HMW species. Increased ratios of HMW to hexameric adiponectin could be achieved rapidly under oxidizing conditions by promoting disulfide rearrangement. Conclusions Based upon these observations, we propose oxidative assembly of multi-subunit adiponectin complexes in a defined and stable redox environment is favored under oxidizing conditions coupled with high rates of disulfide rearrangement.

  5. Oligomeric procyanidins of French maritime pine bark extract (Pycnogenol) effectively inhibit alpha-glucosidase.

    Science.gov (United States)

    Schäfer, Angelika; Högger, Petra

    2007-07-01

    The standardized maritime pine bark extract (Pycnogenol) was reported to exert clinical anti-diabetic effects after peroral intake. However, an increased insulin secretion was not observed after administration of the extract to patients. Our aim was to elucidate whether the described clinical effects of Pycnogenol are related to inhibition of alpha-glucosidase. Therefore, we analyzed the inhibitory activity of Pycnogenol, green tea extract and acarbose towards alpha-glucosidase. Furthermore, we explored different fractions of Pycnogenol containing compounds of diverse molecular masses from polyphenolic monomers, dimers and higher oligomers to uncover which components exhibited the most pronounced inhibitory activity. We found that Pycnogenol exhibited the most potent inhibition (IC(50) about 5 microg/mL) on alpha-glucosidase compared to green tea extract (IC(50) about 20 microg/mL) and acarbose (IC(50) about 1mg/mL). The inhibitory action of Pycnogenol was stronger in extract fractions containing higher procyanidin oligomers. The results obtained assign a novel, local effect to oligomeric procyanidins and contribute to the explanation of glucose-lowering effects of Pycnogenol observed in clinical trials with diabetic patients.

  6. Oligomerization of 10,16-Dihydroxyhexadecanoic Acid and Methyl 10,16-Dihydroxyhexadecanoate Catalyzed by Lipases

    Directory of Open Access Journals (Sweden)

    Daniel Arrieta-Baez

    2013-08-01

    Full Text Available The main monomer of tomato cuticle, 10,16-dihydroxyhexadecanoic acid (10,16-DHPA and its methyl ester derivative (methyl-10,16-dihydroxyhexadecanote; methyl-10,16-DHHD, were used to study their oligomerization reactions catalyzed by five lipases: Candida antarctica lipase B (CAL-B, Rhizomucor miehei lipase (RM, Thermomyces lanuginosus lipase (TL, Pseudomonas cepacia lipase (PCL and porcine pancreatic lipase (PPL. For 10,16-DHPA, optimum yields were obtained at 60 °C using toluene and 2-methyl-2-butanol (2M2B as solvent, while for methyl-10,16-DHHD the bests yields were obtained in toluene and acetonitrile. Both reactions leaded to linear polyesters according to the NMR and FT-IR analysis, and there was no data indicating the presence of branched polymers. Using optimized conditions, poly(10,16-DHPA and poly(methyl-10,16-DHHD with Mw = 814 and Mn = 1,206 Da, and Mw = 982 and Mn = 860 Da, respectively, were formed according to their MALDI-TOF MS and ESI-MS data. The self-assembly of the polyesters obtained were analyzed by AFM.

  7. Strong Screening Effect of Polyhedral Oligomeric Silsesquioxanes (POSS Nanoparticles on Hydrogen Bonded Polymer Blends

    Directory of Open Access Journals (Sweden)

    Chin-Wei Chiou

    2014-03-01

    Full Text Available In this study we used anionic living polymerization to prepare two different homopolymers: a poly(methyl methacrylate (PMMA and a PMMA derivative presenting polyhedral oligomeric silsesquioxane (PMA-POSS units as its side chains. We then employed differential scanning calorimetry (DSC, Fourier transform infrared (FTIR spectroscopy, and wide-angle X-ray diffraction (WAXD to investigate the miscibility and specific interactions of PMMA and PMA-POSS with three hydrogen bonding donor compounds: poly(vinyl phenol (PVPh, phenolic resin, and bisphenol A (BPA. DSC revealed that all of the PVPh/PMMA, phenolic/PMMA, and BPA/PMMA blends exhibited a single glass transition temperature, characteristic of miscible systems; FTIR spectroscopic analyses revealed that such miscibility resulted from hydrogen bonding interactions between the C=O groups of PMMA and the OH groups of these three hydrogen bonding donor compounds. In contrast, all of the PVPh/PMA-POSS, phenolic/PMA-POSS, and BPA/PMA-POSS blends were immiscible: DSC revealed two glass transition temperatures arising from strong screening effects (FTIR spectroscopy and high degrees of aggregation (WAXD of the POSS nanoparticles. We propose that the value of the intramolecular screening effect (γ should be very close to 1 for all PMA-POSS blend systems when POSS nanoparticles appear as the side chains of PMMA, such that the OH groups of the hydrogen bonding donor compounds cannot interact with the C=O groups of PMA-POSS.

  8. Staphylococcus aureus thiaminase II: oligomerization warrants proteolytic protection against serine proteases.

    Science.gov (United States)

    Begum, Afshan; Drebes, Julia; Kikhney, Alexey; Müller, Ingrid B; Perbandt, Markus; Svergun, Dmitri; Wrenger, Carsten; Betzel, Christian

    2013-12-01

    Staphylococcus aureus TenA (SaTenA) is a thiaminase type II enzyme that catalyzes the deamination of aminopyrimidine, as well as the cleavage of thiamine into 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP) and 5-(2-hydroxyethyl)-4-methylthiazole (THZ), within thiamine (vitamin B1) metabolism. Further, by analogy with studies of Bacillus subtilis TenA, SaTenA may act as a regulator controlling the secretion of extracellular proteases such as the subtilisin type of enzymes in bacteria. Thiamine biosynthesis has been identified as a potential drug target of the multi-resistant pathogen S. aureus and therefore all enzymes involved in the S. aureus thiamine pathway are presently being investigated in detail. Here, the structure of SaTenA, determined by molecular replacement and refined at 2.7 Å resolution to an R factor of 21.6% with one homotetramer in the asymmetric unit in the orthorhombic space group P212121, is presented. The tetrameric state of wild-type (WT) SaTenA was postulated to be the functional biological unit and was confirmed by small-angle X-ray scattering (SAXS) experiments in solution. To obtain insights into structural and functional features of the oligomeric SaTenA, comparative kinetic investigations as well as experiments analyzing the structural stability of the WT SaTenA tetramer versus a monomeric SaTenA mutant were performed.

  9. Serum cartilage oligomeric matrix protein: is there a repeated bout effect?

    Directory of Open Access Journals (Sweden)

    Michael Behringer

    2014-10-01

    Full Text Available The primary aim of the present study was to investigate if there is a repeated bout effect for cartilage tissue, evident in the marker serum cartilage oligomeric matrix protein (sCOMP. Ten healthy male subjects (26.4±3.14 years performed two high impact interventions (100 drop jumps with a 30 second interval carried out at a 3 week interval. After each intervention, sCOMP and muscle soreness were assessed on 8 and 6 occasions respectively. Muscle soreness was determined via a visual analog scale with a maximum pain score of 10. sComp levels did not show a blunted response after the second bout (Bout 1: 12.2±3.3 U/L−1; Bout 2: 13.1±4.0 U/L−1; P>0.05. Remarkably, sCOMP increased from baseline levels by 16% after bout 1 and 15% after bout 2. Muscle soreness was blunted following the second intervention (Bout 1: 5.0±1.8; Bout 2: 1.6±0.8. Unlike the known repeated bout effect for muscle damage markers, sCOMP levels do not show a blunted response after two similar loading interventions. This information on biomarker behavior is essential to clinicians attempting to use this marker as an indicator of cartilage damage associated with the development or progression of osteoarthritis.

  10. AFM study of glucagon fibrillation via oligomeric structures resulting in interwoven fibrils

    Energy Technology Data Exchange (ETDEWEB)

    Dong Mingdong [Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, DK-8000 Aarhus C (Denmark); Hovgaard, Mads Bruun [Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, DK-8000 Aarhus C (Denmark); Xu Sailong [Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, DK-8000 Aarhus C (Denmark); Otzen, Daniel Erik [Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, DK-8000 Aarhus C (Denmark); Besenbacher, Flemming [Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, DK-8000 Aarhus C (Denmark)

    2006-08-28

    Glucagon is a 29-residue amphiphatic hormone involved in the regulation of blood glucose levels in conjunction with insulin. In concentrated aqueous solutions, glucagon spontaneously aggregates to form amyloid fibrils, destroying its biological activity. In this study we utilize the atomic force microscope (AFM) to elucidate the fibrillation mechanism of glucagon at the nanoscale under acidic conditions (pH 2.0) by visualizing the nanostructures of fibrils formed at different stages of the incubation. Hollow disc-shaped oligomers form at an early stage in the process and subsequently rearrange to more solid oligomers. These oligomers co-exist with, and most likely act as precursors for, protofibrils, which subsequently associate to form at least three different classes of higher-order fibrils of different heights. A repeat unit of around 50 nm along the main fibril axis suggests a helical arrangement of interwoven protofibrils. The diversity of oligomeric and fibrillar arrangements formed at pH 2.0 complements previous spectroscopic analyses that revealed that fibrils formed under different conditions can differ substantially in stability and secondary structure.

  11. Anticancer effects of oligomeric proanthocyanidins on human colorectal cancer cell line, SNU-C4

    Institute of Scientific and Technical Information of China (English)

    Youn-Jung Kim; Hae-Jeong Park; Seo-Hyun Yoon; Mi-Ja Kim; Kang-Hyun Leem; Joo-Ho Chung; Hye-Kyung Kim

    2005-01-01

    AIM: Oligomeric proanthocyanidins (OPC), natural polyphenolic compounds found in plants, are known to have antioxidant and anti-cancer effects. We investigated whether the anti-cancer effects of the OPC are induced by apoptosis on human colorectal cancer cell line, SNU-C4.METHODS: Colorectal cancer cell line, SNU-C4 was cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum. The cytotoxic effect of OPC was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenylt-etrazolium bromide (MTT) assay. To find out the apoptotic cell death, 4, 6-diamidino-2-phenylindole (DAPI) staining,terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay, reverse transcriptionpolymerase chain reaction (RT-PCR), and caspase-3 enzyme assay were performed.RESULTS: In this study, cytotoxic effect of OPC on SNUC4 cells appeared in a dose-dependent manner. OPC treatment (100 μg/mL) revealed typical morphological apoptotic features. Additionally OPC treatment (100 μg/mL)increased level of BAX and CASPASE-3, and decreased level of BCL-2 mRNA expression. Caspase-3 enzyme activity was also significantly increased by treatment of OPC (100 μg/mL) compared with control.CONCLUSION: These data indicate that OPC caused cell death by apoptosis through caspase pathways on human colorectal cancer cell line, SNU-C4.

  12. Coatings of molecularly imprinted polymers based on polyhedral oligomeric silsesquioxane for open tubular capillary electrochromatography.

    Science.gov (United States)

    Zhao, Qing-Li; Zhou, Jin; Zhang, Li-Shun; Huang, Yan-Ping; Liu, Zhao-Sheng

    2016-05-15

    Polyhedral oligomeric silsesquioxane (POSS) was successfully applied, for the first time, to prepare imprinted monolithic coating for capillary electrochromatography. The imprinted monolithic coating was synthesized with a mixture of PSS-(1-Propylmethacrylate)-heptaisobutyl substituted (MA 0702), S-amlodipine (template), methacrylic acid (functional monomer), and 2-methacrylamidopropyl methacrylate (crosslinker), in a porogenic mixture of toluene-isooctane. The influence of synthesis parameters on the imprinting effect and separation performance, including the amount of MA 0702, the ratio of template to monomer, and the ratio of monomer to crosslinker, was investigated. The greatest resolution for enantiomers separation on the imprinted monolithic column prepared with MA 0702 was up to 22.3, about 2 times higher than that prepared in absence of the POSS. Column efficiency on the POSS-based MIP coatings was beyond 30,000 plate m(-1). The comparisons between MIP coating synthesized with the POSS and without the POSS were made in terms of selectivity, column efficiency, and resolution. POSS-based MIP capillaries with naproxen or zopiclone was also prepared and separation of enantiomers can be achieved.

  13. Non-oxidative dehydro-oligomerization of methane to higher molecular weight hydrocarbons at low temperatures

    Institute of Scientific and Technical Information of China (English)

    王林胜; 徐奕德; 陶龙骧

    1997-01-01

    The non-oxidative dehydro-oligomerization of methane to higher molecular weight hydrocarbons such as aroma tics and C2 hydrocarbons in a low temperature range of 773-973 K with Mo/HZSM-5,Mo-Zr/HZSM-5 and Mo-W/HZSM-5 catalysts is studied.The means for enhancing the activity and stability of the Mo-containing catalysts under the reaction conditions is reported.Quite a stable methane conversion rate of over 10% with a high selectivity to the higher hydrocarbons has been obtained at a temperature of 973 K.Pure methane conversions of about 5.2% and 2.0% have been obtained at 923 and 873 K,respectively.In addition,accompanied by the C2-C3 mixture,tht- methane reaction can be initiated even at a lower temperature and the conversion rate of methane is enhanced by the presence of tne initiator of C2-C3 hydrocarbons.Compared with methane oxidative coupling to ethylene,the novel way for methane transformation is significant and reasonable for its lower reaction temperatures and high selectivity to the desired prod

  14. Small-molecule inhibition of STOML3 oligomerization reverses pathological mechanical hypersensitivity.

    Science.gov (United States)

    Wetzel, Christiane; Pifferi, Simone; Picci, Cristina; Gök, Caglar; Hoffmann, Diana; Bali, Kiran K; Lampe, André; Lapatsina, Liudmila; Fleischer, Raluca; Smith, Ewan St John; Bégay, Valérie; Moroni, Mirko; Estebanez, Luc; Kühnemund, Johannes; Walcher, Jan; Specker, Edgar; Neuenschwander, Martin; von Kries, Jens Peter; Haucke, Volker; Kuner, Rohini; Poulet, James F A; Schmoranzer, Jan; Poole, Kate; Lewin, Gary R

    2017-02-01

    The skin is equipped with specialized mechanoreceptors that allow the perception of the slightest brush. Indeed, some mechanoreceptors can detect even nanometer-scale movements. Movement is transformed into electrical signals via the gating of mechanically activated ion channels at sensory endings in the skin. The sensitivity of Piezo mechanically gated ion channels is controlled by stomatin-like protein-3 (STOML3), which is required for normal mechanoreceptor function. Here we identify small-molecule inhibitors of STOML3 oligomerization that reversibly reduce the sensitivity of mechanically gated currents in sensory neurons and silence mechanoreceptors in vivo. STOML3 inhibitors in the skin also reversibly attenuate fine touch perception in normal mice. Under pathophysiological conditions following nerve injury or diabetic neuropathy, the slightest touch can produce pain, and here STOML3 inhibitors can reverse mechanical hypersensitivity. Thus, small molecules applied locally to the skin can be used to modulate touch and may represent peripherally available drugs to treat tactile-driven pain following neuropathy.

  15. Synthesis and Self-Assembly Behaviors of Polyhedral Oligomeric Silsesquioxane Based Giant Molecular Shape Amphiphiles

    Science.gov (United States)

    Yue, Kan; Yu, Xinfei; Liu, Chang; Zhang, Wen-Bin; Cheng, Stephen

    2013-03-01

    Recently, our group has focus on the synthesis and characterization of novel giant molecular shape amphiphiles (GMSAs) based on functionalized molecular nanoparticles (MNPs), such as polyhedral oligomeric silsesquioxane (POSS), tethered with polymeric tails. A general synthetic method via the combination of sequential ?click? reactions has been developed and several model GMSAs with various tail lengths and distinct molecular topologies, which can be referred as the ?giant surfactants?, ?giant lipids?, ?giant gemini surfactants?, and ?giant bolaform surfactants? etc., have been demonstrated. Studies on their self-assembly behaviors in the bulk have revealed the formation of different ordered mesophase structures with feature sizes around 10 nanometers, which have been investigated in detail by small angle X-ray scattering (SAXS) technique and transmission electron microscopy (TEM). These findings have general implications on understanding the underlying principles of self-assembly behaviors of GMSAs, and might have potential applications in nano-patterning technology. This work is supported by NSF (DMR-0906898) and the Joint-Hope Foundation.

  16. Cartilage Oligomeric Matrix Protein Angiopoeitin-1 Provides Benefits During Nerve Regeneration In Vivo and In Vitro.

    Science.gov (United States)

    Qiu, Longhai; He, Bo; Hu, Jun; Zhu, Zhaowei; Liu, Xiaolin; Zhu, Jiakai

    2015-12-01

    Our group pioneered the study of nerve regeneration in China and has successfully developed human "acellular nerve grafts (ACNGs)". However, our clinical studies revealed that the effects of ACNGs for long and large nerve defects are far from satisfactory. To improve the efficacy of ACNGs, we combined Cartilage oligomeric matrix protein angiopoietin-1 (COMP-Ang1) with ACNGs in rat sciatic nerve injury models and observed the outcomes via angiographic, morphological, and functional analyses. Co-cultures of endothelial cells (ECs) and dorsal root ganglion neurons (DRGs) were also used to characterize the relationship between neovascularization and nerve regeneration. The results showed significant improvements in early neovascularization, nerve regeneration, and functional outcomes in vivo in the ACNG + COMP-Ang1 group. In vitro, neurite length, and density as well as the expression levels of neurofilament 68 (NF68) and phosphorylated-Tie-2 (p-Tie-2) significantly increased when ECs were co-cultured with DRGs using COMP-Ang1. p-Tie-2 expression dramatically decreased after treatment with a Tie-2 kinase inhibitor (S157701), which consequently decreased the level of NF68. COMP-Ang1 can be concluded to promote early neovascularization followed by brisk nerve regeneration, and the mechanism of this regeneration may involve the modulation of the p-Tie-2 and Tie-2 receptors on ECs. These findings demonstrate that ACNGs can be modified using COMP-Ang1 to improve their efficacy in repairing peripheral nerve defects in clinical trials.

  17. The substitution of Proline 168 favors Bax oligomerization and stimulates its interaction with LUVs and mitochondria.

    Science.gov (United States)

    Simonyan, Lilit; Légiot, Alexandre; Lascu, Ioan; Durand, Grégory; Giraud, Marie-France; Gonzalez, Cécile; Manon, Stéphen

    2017-06-01

    Bax is a major player in the apoptotic process, being at the core of the mitochondria permeabilization events. In spite of the major recent advances in the knowledge of Bax organization within the membrane, the precise behavior of the C-terminal helix α9 remains elusive, since it was absent from the resolved structure of active Bax. The Proline 168 (P168) residue, located in the short loop between α8 and α9, has been the target of site-directed mutagenesis experiments, with conflicting results. We have produced and purified a recombinant mutant Bax-P168A, and we have compared its behavior with that of wild-type Bax in a series of tests on Large Unilamellar Vesicles (LUVs) and isolated mitochondria. We conclude that Bax-P168A had a greater ability to oligomerize and bind to membranes. Bax-P168A was not more efficient than wild-type Bax to permeabilize liposomes to small molecules but was more prone to release cytochrome c from mitochondria. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. The oligomeric integrity of toposome is essential for its morphogenetic function.

    Science.gov (United States)

    Scaturro, G; Zito, F; Matranga, V

    1998-01-01

    Sea urchin embryos are uniquely suitable for the study of morphogenetic cell interactions. Efforts to identify the molecules responsible for morphogenetic cell adhesion led to the isolation of a 22S glycoprotein complex from Paracentrotus lividus sea urchin embryo, that has been called toposome. The biological activity of toposome in mediating cellular adhesion has been fully documented. Its function in determining positional guidance during the development of the sea urchin embryo has been proposed. Here studies on the molecular structure of toposome are reported showing that, under non-reducing conditions, it is resolved in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) in a major band with an apparent molecular weight of 260 kDa, a doublet of 180-160 kDa and a lower band of 80 kDa. Digestion with EndoH endoglycosidase reduced the molecular sizes of the bands of 10%, 20% and 40%, respectively. In order to establish if the oligomeric integrity of toposome was essential for its function, the biological activity of each subunit on cells dissociated from sea urchin blastula embryos was tested. The resulting swimming embryoids were lacking skeleton, while reaggregating cells supplemented with native toposome developed into pluteus-like structures with skeletal elements.

  19. Adaptive Forgetting Factor Fictitious Play

    CERN Document Server

    Smyrnakis, Michalis

    2011-01-01

    It is now well known that decentralised optimisation can be formulated as a potential game, and game-theoretical learning algorithms can be used to find an optimum. One of the most common learning techniques in game theory is fictitious play. However fictitious play is founded on an implicit assumption that opponents' strategies are stationary. We present a novel variation of fictitious play that allows the use of a more realistic model of opponent strategy. It uses a heuristic approach, from the online streaming data literature, to adaptively update the weights assigned to recently observed actions. We compare the results of the proposed algorithm with those of stochastic and geometric fictitious play in a simple strategic form game, a vehicle target assignment game and a disaster management problem. In all the tests the rate of convergence of the proposed algorithm was similar or better than the variations of fictitious play we compared it with. The new algorithm therefore improves the performance of game-t...

  20. Why Play Outside? Problematising Outdoor Play as a Biopedagogical Task

    Science.gov (United States)

    Robinson, Daniel B.; Barrett, Joe

    2017-01-01

    Although outdoor play has been widely recognised for the many benefits it affords children, some have rationalised the need for it based on goals related to physical health. More specifically, these instrumental goals have been closely related to obesity, overweight, and/or physical (in)activity. Adhering to obesity discourses and the notion of a…

  1. Parent-Child Play across Cultures: Advancing Play Research

    Science.gov (United States)

    Roopnarine, Jaipaul L.; Davidson, Kimberly L.

    2015-01-01

    In this article, the authors argue for a greater understanding of children's play across cultures through better integration of scientific thinking about the developed and developing societies, through consideration of socialization beliefs and goals, and, finally, through the use of more complex models in research investigations. They draw on…

  2. Key residues for the oligomerization of A{beta}42 protein in Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Ngo, Sam [Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA 90095 (United States); Guo, Zhefeng, E-mail: zhefeng@ucla.edu [Department of Neurology, Brain Research Institute, Molecular Biology Institute, University of California, Los Angeles, CA 90095 (United States)

    2011-10-28

    Highlights: Black-Right-Pointing-Pointer A{beta} oligomers are neurotoxins and likely the causing agents for Alzheimer's disease. Black-Right-Pointing-Pointer A{beta}42 fusion protein form globular oligomers. Black-Right-Pointing-Pointer A{beta}42 fusion protein oligomers contain SDS-resistant tetramers and hexamers. Black-Right-Pointing-Pointer Cysteine substitutions at residues 31, 32, 34, 39-41 disrupt A{beta}42 oligomerization. -- Abstract: Deposition of amyloid fibrils consisting of amyloid {beta} (A{beta}) protein as senile plaques in the brain is a pathological hallmark of Alzheimer's disease. However, a growing body of evidence shows that soluble A{beta} oligomers correlate better with dementia than fibrils, suggesting that A{beta} oligomers may be the primary toxic species. The structure and oligomerization mechanism of these A{beta} oligomers are crucial for developing effective therapeutics. Here we investigated the oligomerization of A{beta}42 in the context of a fusion protein containing GroES and ubiquitin fused to the N-terminus of A{beta} sequence. The presence of fusion protein partners, in combination with a denaturing buffer containing 8 M urea at pH 10, is unfavorable for A{beta}42 aggregation, thus allowing only the most stable structures to be observed. Transmission electron microscopy showed that A{beta}42 fusion protein formed globular oligomers, which bound weakly to thioflavin T and Congo red. SDS-PAGE shows that A{beta}42 fusion protein formed SDS-resistant hexamers and tetramers. In contrast, A{beta}40 fusion protein remained as monomers on SDS gel, suggesting that the oligomerization of A{beta}42 fusion protein is not due to the fusion protein partners. Cysteine scanning mutagenesis at 22 residue positions further revealed that single cysteine substitutions of the C-terminal hydrophobic residues (I31, I32, L34, V39, V40, and I41) led to disruption of hexamer and tetramer formation, suggesting that hydrophobic interactions

  3. Modular robotics for playful physiotherapy

    DEFF Research Database (Denmark)

    Lund, Henrik Hautop

    2009-01-01

    We developed modular robotic tiles to be used for playful physiotherapy, which is supposed to motivate patients to engage in and perform physical rehabilitation exercises. We tested the modular robotic tiles for an extensive period of time (3 years) in daily use in a hospital rehabilitation unit e.......g. for cardiac patients. Also, the tiles were tested for performing physical rehabilitation of stroke patients in their private home. In all pilot test cases qualitative feedback indicate that the patients find the playful use of modular robotic tiles engaging and motivating for them to perform...... the rehabilitation. Also, initial pilot test data suggest that some playful exercises on the tiles demand an average heart rate of 75% and 86% of the maximum heart rate....

  4. Rapport. Play and Learn Innovation

    DEFF Research Database (Denmark)

    Larsen, Maria Neumann; Søgaard, Karoline

    Erfaringer og anbefalinger fra innovationsprojektet Play and Learn, hvor pædagoger har arbejdet med sprogstimulering af børn fra 3-9 år. Legende læring i daglige rutiner og pædagogiske aktiviteter har været fokuspunktet.......Erfaringer og anbefalinger fra innovationsprojektet Play and Learn, hvor pædagoger har arbejdet med sprogstimulering af børn fra 3-9 år. Legende læring i daglige rutiner og pædagogiske aktiviteter har været fokuspunktet....

  5. Let's 'play' with molecular pharmacology.

    Science.gov (United States)

    Choudhury, Supriyo; Pradhan, Richeek; Sengupta, Gairik; Das, Manisha; Chatterjee, Manojit; Roy, Ranendra Kumar; Chatterjee, Suparna

    2015-01-01

    Understanding concepts of molecular mechanisms of drug action involves sequential visualization of physiological processes and drug effects, a task that can be difficult at an undergraduate level. Role-play is a teaching-learning methodology whereby active participation of students as well as clear visualization of the phenomenon is used to convey complex physiological concepts. However, its use in teaching drug action, a process that demands understanding of a second level of complexity over the physiological process, has not been investigated. We hypothesized that role-play can be an effective and well accepted method for teaching molecular pharmacology. In an observational study, students were guided to perform a role-play on a selected topic involving drug activity. Students' gain in knowledge was assessed comparing validated pre- and post-test questionnaires as well as class average normalized gain. The acceptance of role-play among undergraduate medical students was evaluated by Likert scale analysis and thematic analysis of their open-ended written responses. Significant improvement in knowledge (P pharmacology in undergraduate medical curricula.

  6. Playing with Protons CREATIONS Demonstrator

    CERN Document Server

    Alexopoulos, Angelos

    2017-01-01

    This document describes Playing with Protons, a CMS education initiative that seeks to enhance teachers’ pedagogical practice with creative, hands-on methodologies through which 10-12 year old students can, in turn, get engaged effectively with science, technology and innovation.

  7. For the Phenomenology of Play

    Directory of Open Access Journals (Sweden)

    Roberto Farné

    2016-10-01

    Full Text Available The success of phenomenology in contemporary culture is due above all to the new approach to knowledge that has been proposed, breaking with the traditional objectivism of scientific knowledge and placing the “phenomenon” at the centre of the relationship between the subject and the world. Everyday reality, the language of concrete things, have become fully-fledged targets of philosophical thought. While Eugen Fink, student of Husserl, elects the phenomenon of play as the “symbol of the world”, the original interpretation of man’s relation to the world, in Italy Piero Bertolini redefines the scientific basis of pedagogy according to phenomenological categories and places play among the fundamental fields of experience of education. On one hand overcoming the traditional educational instrumentalisation of play, on the other its sterile reduction to a consumer experience, Bertolini brings play back to its authentic dimension in which risk, error, adventure are constituent parts, the “active ingredients” of his pedagogy.

  8. Electronic Instruments -- Played or Used?

    Science.gov (United States)

    Ulveland, Randall Dana

    1998-01-01

    Compares the experience of playing an acoustic instrument to an electronic instrument by analyzing the constant structures and relationships between the experiences. Concludes that students' understanding of the physical experience of making music increases when experiences with acoustic instruments precede their exposure to electronic…

  9. Moral Education through Play Therapy

    Science.gov (United States)

    Mahalle, Salwa; Zakaria, Gamal Abdul Nasir; Nawi, Aliff

    2014-01-01

    This paper will discuss on how sand therapy (as one type of play therapies) can be applied as an additional technique or approach in counseling. The research questions for this study are to see what are the development, challenges faced by the therapist during the sessions given and how sand therapy can aid to the progress of the client. It is a…

  10. Obama Plays Cheerleader for STEM

    Science.gov (United States)

    Robelen, Erik W.

    2010-01-01

    Amid a struggling economy, a raft of foreign-policy headaches, and the tail end of a heated campaign season, President Barack Obama carved out time in his schedule last month to watch students in the State Dining Room demonstrate a solar-powered model car, a water-purification system, and a soccer-playing robot. The science fair was the fifth…

  11. Playing with a digital swing

    DEFF Research Database (Denmark)

    Skovbjerg, Helle Marie

    2017-01-01

    Based on a field study in a kindergarten among children in Denmark, this paper explores playing activities on a digital swing, the SON-X Octavia (SON-X) and its Applause application. SON-X is an interactive sound unit that can be attached to any swing chain. Here, I explore the relationship betwe...

  12. Play for learning and learning for play: Children’s play in a toddler group

    Directory of Open Access Journals (Sweden)

    Anne Greve

    2013-10-01

    Full Text Available There is a concern that children’s right to play is restricted as a result of the governments’ narrow focus on school preparatory activities and learning. Play and learning are rights embodied in the United Nations convention on the rights of the child. This article discusses how play and learning are organized in the everyday life of a Norwegian toddler group. Critical voices claim that there is not enough structure and that there should be more teaching and mapping to facilitate early intervention in Norwegian kindergartens. The article suggests that the critics’ claim can be countered by asking if there are too few teachers with adequate education and too large groups of children.

  13. New nanoplatforms based on UCNPs linking with polyhedral oligomeric silsesquioxane (POSS) for multimodal bioimaging

    Science.gov (United States)

    Ge, Xiaoqian; Dong, Liang; Sun, Lining; Song, Zhengmei; Wei, Ruoyan; Shi, Liyi; Chen, Haige

    2015-04-01

    A new and facile method was used to transfer upconversion luminescent nanoparticles from hydrophobic to hydrophilic using polyhedral oligomeric silsesquioxane (POSS) linking on the surface of upconversion nanoparticles. In comparison with the unmodified upconversion nanoparticles, the POSS modified upconversion nanoplatforms [POSS-UCNPs(Er), POSS-UCNPs(Tm)] displayed good monodispersion in water and exhibited good water-solubility, while their particle size did not change substantially. Due to the low cytotoxicity and good biocompatibility as determined by methyl thiazolyl tetrazolium (MTT) assay and histology and hematology analysis, the POSS modified upconversion nanoplatforms were successfully applied to upconversion luminescence imaging of living cells in vitro and nude mouse in vivo (upon excitation at 980 nm). In addition, the doped Gd3+ ion endows the POSS-UCNPs with effective T1 signal enhancement and the POSS-UCNPs were successfully applied to in vivo magnetic resonance imaging (MRI) for a Kunming mouse, which makes them potential MRI positive-contrast agents. More importantly, the corner organic groups of POSS can be easily modified, resulting in kinds of POSS-UCNPs with many potential applications. Therefore, the method and results may provide more exciting opportunities for multimodal bioimaging and multifunctional applications.A new and facile method was used to transfer upconversion luminescent nanoparticles from hydrophobic to hydrophilic using polyhedral oligomeric silsesquioxane (POSS) linking on the surface of upconversion nanoparticles. In comparison with the unmodified upconversion nanoparticles, the POSS modified upconversion nanoplatforms [POSS-UCNPs(Er), POSS-UCNPs(Tm)] displayed good monodispersion in water and exhibited good water-solubility, while their particle size did not change substantially. Due to the low cytotoxicity and good biocompatibility as determined by methyl thiazolyl tetrazolium (MTT) assay and histology and hematology

  14. Quantitative FRET imaging of leptin receptor oligomerization kinetics in single cells.

    Science.gov (United States)

    Biener, Eva; Charlier, Madia; Ramanujan, V Krishnan; Daniel, Nathalie; Eisenberg, Avital; Bjørbaek, Christian; Herman, Brian; Gertler, Arieh; Djiane, Jean

    2005-12-01

    Leptin, an adipocyte-secreted hormone, signals through activation of its membrane-embedded receptor (LEPR). To study the leptin-induced events occurring in short (LEPRa) and long (LEPRb) LEPRs in the cell membrane, by FRET (fluorescence resonance energy transfer) methodology, the respective receptors, tagged at their C-terminal with CFP (cyan fluorescent protein) or YFP (yellow fluorescent protein), were prepared. The constructs encoding mLEPRa (mouse LEPRa)-YFP and mLEPRa-CFP, mLEPRb-YFP and mLEPRb-CFP were tested for biological activity in transiently transfected CHO cells (Chinese-hamster ovary cells) and HEK-293T cells (human embryonic kidney 293 T cells) for activation of STAT3 (signal transduction and activators of transcription 3)-mediated LUC (luciferase) activity and binding of radiolabelled leptin. All four constructs were biologically active and were as potent as their untagged counterparts. The localization pattern of the fused protein appeared to be confined almost entirely to the cell membrane. The leptin-dependent interaction between various types of receptors in fixed cells were studied by measuring FRET, using fluorescence lifetime imaging microscopy and acceptor photobleaching methods. Both methods yielded similar results, indicating that (1) leptin receptors expressed in the cell membrane exist mostly as preformed LEPRa/LEPRa or LEPRb/LEPRb homo-oligomers but not as LEPRb/LEPRa hetero-oligomers; (2) the appearance of transient leptin-induced FRET in cells transfected with LEPRb/LEPRb reflects both a conformational change that leads to closer interaction in the cytosolic part and a higher FRET signal, as well as de novo homo-oligomerization; (3) in LEPRa/LEPRa, exposure to leptin does not lead to any increase in FRET signalling as the proximity of CFP and YFP fluorophores in space already gives maximal FRET efficiency of the preoligomerized receptors.

  15. Synthesis of polyhedral oligomeric silsesquioxane (POSS) functionalized carbon nanotubes for improved dispersion in polyurethane films

    Science.gov (United States)

    Kou, Xiaonan

    Carbon nanotube (CNT) polymer nanocomposites are promising advanced materials. These materials exhibit the advantages of traditional polymeric materials, such as being light weight and easy to process, combined with the potential to exhibit enhanced mechanical, thermal and electrical properties compared to pure polymers. To achieve substantial improvement of composite properties at low CNT loading, uniform dispersion of CNTs in the polymer matrix and strong CNT-polymer interfacial interaction are needed. However, it is difficult to achieve adequate dispersion and interfacial interactions due to the inert nature of CNTs. In this project, polyhedral oligomeric silsequioxane (POSS) will be used as a dispersing agent for multi-walled carbon nanotubes (MWNTs) in polyurethane (PU) matrices. This dissertation consists of six chapters. Chapter I provides a detailed introduction of the fundamental knowledge of CNTs, PU, and POSS. At the end of this chapter, the motivation and rationale of this research are given. Chapter II establishes the overall goal and specific objectives of this research. Chapter III describes the synthesis and characterization of three POSS modified CNTs and one organosilane modified CNT. Grafting efficiency of the different grafted molecules are calculated and compared. Chapter IV discusses the dispersion behavior of four covalently modified CNTs in both solvents and PU matrices. Differences in dispersion behaviors of the modified CNTs are correlated to the solubility parameters of the grafting molecules and the surface structures of modified CNTs. Chapter V provides further discussion of the dispersion of POSS and silane modified CNTs by reviewing the assessment of the physical properties of PU composites containing the modified CNTs. Morphological, thermal, mechanical and electrical properties are used to estimate the interactions of the modified CNTs with the PU matrix. Chapter VI explores the function of the trisilanolphenyl POSS lithium salt

  16. Organic-inorganic hybrid compounds containing polyhedral oligomeric silsesquioxane for conservation of stone heritage.

    Science.gov (United States)

    Son, Seunghwan; Won, Jongok; Kim, Jeong-Jin; Jang, Yun Deuk; Kang, Yong Soo; Kim, Sa Dug

    2009-02-01

    Alkoxysilane solutions based on tetraethoxysilane (TEOS) have been widely used for the consolidation of decaying heritage stone surfaces. TEOS-based products polymerize within the porous structure of the decaying stone, significantly increasing the cohesion of the grains of stone components. However, they suffer from practical drawbacks, such as crack formation of the gel during the drying phase due to the developing capillary force and dense gel fractures left inside of the stone. In this study, a TEOS-based stone consolidant containing functional (3-glycidoxypropyl)trimethoxysilane (GPTMS) and polyhedral oligomeric silsesquioxane (POSS) has been prepared in order to reduce gel crack formation during the drying phase. The addition of nanometer-sized POSS and/or GPTMS having a flexible segment reduces the capillary force developed during solvent evaporation. The properties of the TEOS/GPTMS/POSS composite solutions were compared with those of commercial products (Wacker OH and Unil sandsteinfestiger OH 1:1). The gelation time was similar to that of commercial consolidants, and the TEOS/GPTMS/POSS solution was stable over a period of up to 6 months. The addition of POSS and GPTMS provided a crack-free gel, while the gel from the commercial consolidants exhibited cracks after drying. The surface hydrophobicity of the treated decayed granite increased with the addition of POSS and GPTMS, and it was higher than that of the commercial product, implying the possibility of POSS and GPTMS as barriers to the penetration of water. This result implies that the TEOS/GPTMS/POSS solution showed a high suitability for the consolidation of granite heritage.

  17. Oligomeric structure and minimal functional unit of the electrogenic sodium bicarbonate cotransporter NBCe1-A.

    Science.gov (United States)

    Kao, Liyo; Sassani, Pakan; Azimov, Rustam; Pushkin, Alexander; Abuladze, Natalia; Peti-Peterdi, Janos; Liu, Weixin; Newman, Debra; Kurtz, Ira

    2008-09-26

    The electrogenic sodium bicarbonate cotransporter NBCe1-A mediates the basolateral absorption of sodium and bicarbonate in the proximal tubule. In this study the oligomeric state and minimal functional unit of NBCe1-A were investigated. Wild-type (wt) NBCe1-A isolated from mouse kidney or heterologously expressed in HEK293 cells was predominantly in a dimeric state as was shown using fluorescence energy transfer, pulldown, immunoprecipitation, cross-linking experiments, and nondenaturing perfluorooctanoate-PAGE. NBCe1-A monomers were found to be covalently linked by S-S bonds. When each of the 15 native cysteine residues were individually removed on a wt-NBCe1-A backbone, dimerization of the cotransporter was not affected. In experiments involving multiple native cysteine residue removal, both Cys(630) and Cys(642) in extracellular loop 3 were shown to mediate S-S bond formation between NBCe1-A monomers. When native NBCe1-A cysteine residues were individually reintroduced into a cysteineless NBCe1-A mutant backbone, the finding that a Cys(992) construct that lacked S-S bonds functioned normally indicated that stable covalent linkage of NBCe1-A monomers was not a necessary requirement for functional activity of the cotransporter. Studies using concatameric constructs of wt-NBCe1-A, whose activity is resistant to methanesulfonate reagents, and an NBCe1-A(T442C) mutant, whose activity is completely inhibited by methanesulfonate reagents, confirmed that NBCe1-A monomers are functional. Our results demonstrate that wt-NBCe1-A is predominantly a homodimer, dependent on S-S bond formation that is composed of functionally active monomers.

  18. Marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS

    Directory of Open Access Journals (Sweden)

    Luciano Ribeiro CORREA NETTO

    2015-10-01

    Full Text Available Marginal integrity is one of the most crucial aspects involved in the clinical longevity of resin composite restorations.Objective To analyze the marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS.Material and Methods A base composite (B was produced with an organic matrix with UDMA/TEGDMA and 70 wt.% of barium borosilicate glass particles. To produce the model composite, 25 wt.% of UDMA were replaced by POSS (P25. The composites P90 and TPH3 (TP3 were used as positive and negative controls, respectively. Marginal integrity (%MI was analyzed in bonded class I cavities. The volumetric polymerization shrinkage (%VS and the polymerization shrinkage stress (Pss - MPa were also evaluated.Results The values for %MI were as follows: P90 (100% = TP3 (98.3% = B (96.9% > P25 (93.2%, (p<0.05. The %VS ranged from 1.4% (P90 to 4.9% (P25, while Pss ranged from 2.3 MPa (P90 to 3.9 MPa (B. For both properties, the composite P25 presented the worst results (4.9% and 3.6 MPa. Linear regression analysis showed a strong positive correlation between %VS and Pss (r=0.97, whereas the correlation between Pss and %MI was found to be moderate (r=0.76.Conclusions The addition of 25 wt.% of POSS in methacrylate organic matrix did not improve the marginal integrity of class I restorations. Filtek P90 showed lower polymerization shrinkage and shrinkage stress when compared to the experimental and commercial methacrylate composite.

  19. Conservation of the oligomeric state of native VDAC1 in detergent micelles.

    Science.gov (United States)

    Clémençon, Benjamin; Fine, Michael; Hediger, Matthias A

    2016-08-01

    The voltage-dependent anion-selective channel (VDAC) is an intrinsic β-barrel membrane protein located within the mitochondrial outer membrane where it serves as a pore, connecting the mitochondria to the cytosol. The high-resolution structures of both the human and murine VDACs have been resolved by X-ray diffraction and nuclear magnetic resonance spectroscopy (NMR) in 2008. However, the structural data are not completely in line with the findings that were obtained after decades of research on biochemical and functional analysis of VDAC. This discrepancy may be related to the fact that structural biology studies of membrane proteins reveal specific static conformations that may not necessarily represent the physiological state. For example, overexpression of membrane proteins in bacterial inclusion bodies or simply the extraction from the native lipid environment using harsh purification methods (i.e. chaotropic agents) can disturb the physiological conformations and the supramolecular assemblies. To address these potential issues, we have developed a method, allowing rapid one step purification of endogenous VDAC expressed in the native mitochondrial membrane without overexpression of recombinant protein or usage of harsh chaotropic extraction procedures. Using the Saccharomyces cerevisiae isoform 1 of VDAC as a model, this method yields efficient purification, preserving VDAC in a more physiological, native state following extraction from mitochondria. Single particle analysis using transmission electron microscopy (TEM) demonstrated conservation of oligomeric assembly after purification. Maintenance of the native state was evaluated using functional assessment that involves an ATP-binding assay by micro-scale thermophoresis (MST). Using this approach, we were able to determine for the first time the apparent KD for ATP of 1.2 mM.

  20. Zinc-induced oligomerization of zinc α2 glycoprotein reveals multiple fatty acid-binding sites.

    Science.gov (United States)

    Zahid, Henna; Miah, Layeque; Lau, Andy M; Brochard, Lea; Hati, Debolina; Bui, Tam T T; Drake, Alex F; Gor, Jayesh; Perkins, Stephen J; McDermott, Lindsay C

    2016-01-01

    Zinc α2 glycoprotein (ZAG) is an adipokine with a class I MHC protein fold and is associated with obesity and diabetes. Although its intrinsic ligand remains unknown, ZAG binds the dansylated C11 fatty acid 11-(dansylamino)undecanoic acid (DAUDA) in the groove between the α1 and α2 domains. The surface of ZAG has approximately 15 weak zinc-binding sites deemed responsible for precipitation from human plasma. In the present study the functional significance of these metal sites was investigated. Analytical ultracentrifugation (AUC) and CD showed that zinc, but not other divalent metals, causes ZAG to oligomerize in solution. Thus ZAG dimers and trimers were observed in the presence of 1 and 2 mM zinc. Molecular modelling of X-ray scattering curves and sedimentation coefficients indicated a progressive stacking of ZAG monomers, suggesting that the ZAG groove may be occluded in these. Using fluorescence-detected sedimentation velocity, these ZAG-zinc oligomers were again observed in the presence of the fluorescent boron dipyrromethene fatty acid C16-BODIPY (4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-hexadecanoic acid). Fluorescence spectroscopy confirmed that ZAG binds C16-BODIPY. ZAG binding to C16-BODIPY, but not to DAUDA, was reduced by increased zinc concentrations. We conclude that the lipid-binding groove in ZAG contains at least two distinct fatty acid-binding sites for DAUDA and C16-BODIPY, similar to the multiple lipid binding seen in the structurally related immune protein CD1c. In addition, because high concentrations of zinc occur in the pancreas, the perturbation of these multiple lipid-binding sites by zinc may be significant in Type 2 diabetes where dysregulation of ZAG and zinc homoeostasis occurs.

  1. Isolated Toll-like receptor transmembrane domains are capable of oligomerization.

    Directory of Open Access Journals (Sweden)

    James I Godfroy

    Full Text Available Toll-like receptors (TLRs act as the first line of defense against bacterial and viral pathogens by initiating critical defense signals upon dimer activation. The contribution of the transmembrane domain in the dimerization and signaling process has heretofore been overlooked in favor of the extracellular and intracellular domains. As mounting evidence suggests that the transmembrane domain is a critical region in several protein families, we hypothesized that this was also the case for Toll-like receptors. Using a combined biochemical and biophysical approach, we investigated the ability of isolated Toll-like receptor transmembrane domains to interact independently of extracellular domain dimerization. Our results showed that the transmembrane domains had a preference for the native dimer partners in bacterial membranes for the entire receptor family. All TLR transmembrane domains showed strong homotypic interaction potential. The TLR2 transmembrane domain demonstrated strong heterotypic interactions in bacterial membranes with its known interaction partners, TLR1 and TLR6, as well as with a proposed interaction partner, TLR10, but not with TLR4, TLR5, or unrelated transmembrane receptors providing evidence for the specificity of TLR2 transmembrane domain interactions. Peptides for the transmembrane domains of TLR1, TLR2, and TLR6 were synthesized to further study this subfamily of receptors. These peptides validated the heterotypic interactions seen in bacterial membranes and demonstrated that the TLR2 transmembrane domain had moderately strong interactions with both TLR1 and TLR6. Combined, these results suggest a role for the transmembrane domain in Toll-like receptor oligomerization and as such, may be a novel target for further investigation of new therapeutic treatments of Toll-like receptor mediated diseases.

  2. Bioactivity and properties of a dental adhesive functionalized with polyhedral oligomeric silsesquioxanes (POSS) and bioactive glass.

    Science.gov (United States)

    Rizk, Marta; Hohlfeld, Lisa; Thanh, Loan Tao; Biehl, Ralf; Lühmann, Nicole; Mohn, Dirk; Wiegand, Annette

    2017-09-01

    This study aimed to analyze the effect of infiltrating a commercial adhesive with nanosized bioactive glass (BG-Bi) particles or methacryl-functionalized polyhedral oligomeric silsesquioxanes (POSS) on material properties and bioactivity. An acetone-based dental adhesive (Solobond Plus adhesive, VOCO GmbH, Cuxhaven, Germany) was infiltrated with nanosized bioactive glass particles (0.1 or 1wt%), or with monofunctional or multifunctional POSS particles (10 or 20wt%). Unfilled adhesive served as control. Dispersion and hydrodynamic radius of the nanoparticles were studied by dynamic light scattering. Set specimens were immersed for 28days in artificial saliva at 37°C, and surfaces were mapped for the formation of calcium phospate (Ca/P) precipitates (scanning electron microscopy/energy-dispersive X-ray spectroscopy). Viscosity (rheometry) and the structural characteristic of the networks were studied, such as degree of conversion (FTIR spectroscopy), sol fraction and water sorption. POSS particles showed a good dispersion of the particles for both types of particles being smaller than 3nm, while the bioactive glass particles had a strong tendency to agglomerate. All nanoparticles induced the formation of Ca/P precipitates. The viscosity of the adhesive was not or only slightly increased by POSS particle addition but strongly increased by the bioactive glass particles. The degree of conversion, water sorption and sol fraction showed a maintained or improved network structure and properties when filled with BG-Bi and multifunctional POSS, however, less polymerization was found when loading a monofunctional POSS. Multifunctional POSS may be incorporated into dental adhesives to provide a bioactive potential without changing material properties adversely. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. Structure–property relationships in hybrid dental nanocomposite resins containing monofunctional and multifunctional polyhedral oligomeric silsesquioxanes

    Directory of Open Access Journals (Sweden)

    Wang WG

    2014-02-01

    Full Text Available Weiguo Wang,1,* Xiang Sun,1,* Li Huang,2,* Yu Gao,1 Jinghao Ban,1 Lijuan Shen,1 Jihua Chen1 1Department of Prosthodontics, 2Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China*These authors contributed equally to this workAbstract: Organic-inorganic hybrid materials, such as polyhedral oligomeric silsesquioxanes (POSS, have the potential to improve the mechanical properties of the methacrylate-based composites and resins used in dentistry. In this article, nanocomposites of methacryl isobutyl POSS (MI-POSS [bears only one methacrylate functional group] and methacryl POSS (MA-POSS [bears eight methacrylate functional groups] were investigated to determine the effect of structures on the properties of dental resin. The structures of the POSS-containing networks were determined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Monofunctional POSS showed a strong tendency toward aggregation and crystallization, while multifunctional POSS showed higher miscibility with the dimethacrylate monomer. The mechanical properties and wear resistance decreased with increasing amounts of MI-POSS, indicating that the MI-POSS agglomerates act as the mechanical weak point in the dental resins. The addition of small amounts of MA-POSS improved the mechanical and shrinkage properties. However, samples with a higher MA-POSS concentration showed lower flexural strength and flexural modulus, indicating that there is a limited range in which the reinforcement properties of MA-POSS can operate. This concentration dependence is attributed to phase separation at higher concentrations of POSS, which affects the structural integrity, and thus, the mechanical and shrinkage properties of the dental resin. Our results show that resin with 3% MA-POSS is a potential candidate for resin-based dental materials

  4. Binding and Oligomerization of Modified and Native Bt Toxins in Resistant and Susceptible Pink Bollworm.

    Directory of Open Access Journals (Sweden)

    Josue Ocelotl

    Full Text Available Insecticidal proteins from Bacillus thuringiensis (Bt are used extensively in sprays and transgenic crops for pest control, but their efficacy is reduced when pests evolve resistance. Better understanding of the mode of action of Bt toxins and the mechanisms of insect resistance is needed to enhance the durability of these important alternatives to conventional insecticides. Mode of action models agree that binding of Bt toxins to midgut proteins such as cadherin is essential for toxicity, but some details remain unresolved, such as the role of toxin oligomers. In this study, we evaluated how Bt toxin Cry1Ac and its genetically engineered counterpart Cry1AcMod interact with brush border membrane vesicles (BBMV from resistant and susceptible larvae of Pectinophora gossypiella (pink bollworm, a global pest of cotton. Compared with Cry1Ac, Cry1AcMod lacks 56 amino acids at the amino-terminus including helix α-1; previous work showed that Cry1AcMod formed oligomers in vitro without cadherin and killed P. gossypiella larvae harboring cadherin mutations linked with >1000-fold resistance to Cry1Ac. Here we found that resistance to Cry1Ac was associated with reduced oligomer formation and insertion. In contrast, Cry1AcMod formed oligomers in BBMV from resistant larvae. These results confirm the role of cadherin in oligomerization of Cry1Ac in susceptible larvae and imply that forming oligomers without cadherin promotes toxicity of Cry1AcMod against resistant P. gossypiella larvae that have cadherin mutations.

  5. Rapid mutation of endogenous zebrafish genes using zinc finger nucleases made by Oligomerized Pool ENgineering (OPEN.

    Directory of Open Access Journals (Sweden)

    Jonathan E Foley

    Full Text Available BACKGROUND: Customized zinc finger nucleases (ZFNs form the basis of a broadly applicable tool for highly efficient genome modification. ZFNs are artificial restriction endonucleases consisting of a non-specific nuclease domain fused to a zinc finger array which can be engineered to recognize specific DNA sequences of interest. Recent proof-of-principle experiments have shown that targeted knockout mutations can be efficiently generated in endogenous zebrafish genes via non-homologous end-joining-mediated repair of ZFN-induced DNA double-stranded breaks. The Zinc Finger Consortium, a group of academic laboratories committed to the development of engineered zinc finger technology, recently described the first rapid, highly effective, and publicly available method for engineering zinc finger arrays. The Consortium has previously used this new method (known as OPEN for Oligomerized Pool ENgineering to generate high quality ZFN pairs that function in human and plant cells. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that OPEN can also be used to generate ZFNs that function efficiently in zebrafish. Using OPEN, we successfully engineered ZFN pairs for five endogenous zebrafish genes: tfr2, dopamine transporter, telomerase, hif1aa, and gridlock. Each of these ZFN pairs induces targeted insertions and deletions with high efficiency at its endogenous gene target in somatic zebrafish cells. In addition, these mutations are transmitted through the germline with sufficiently high frequency such that only a small number of fish need to be screened to identify founders. Finally, in silico analysis demonstrates that one or more potential OPEN ZFN sites can be found within the first three coding exons of more than 25,000 different endogenous zebrafish gene transcripts. CONCLUSIONS AND SIGNIFICANCE: In summary, our study nearly triples the total number of endogenous zebrafish genes successfully modified using ZFNs (from three to eight and suggests that OPEN

  6. Composite polymer electrolyte containing ionic liquid and functionalized polyhedral oligomeric silsesquioxanes for anhydrous PEM applications.

    Science.gov (United States)

    Subianto, Surya; Mistry, Mayur K; Choudhury, Namita Roy; Dutta, Naba K; Knott, Robert

    2009-06-01

    A new type of supported liquid membrane was made by combining an ionic liquid (IL) with a Nafion membrane reinforced with multifunctional polyhedral oligomeric silsesquioxanes (POSSs) using a layer-by-layer strategy for anhydrous proton-exchange membrane (PEM) application. The POSS was functionalized by direct sulfonation, and the sulfonated POSS (S-POSS) was incorporated into Nafion 117 membranes by the infiltration method. The resultant hybrid membrane shows strong ionic interaction between the Nafion matrix and the multifunctional POSS, resulting in increased glass transition temperature and thermal stability at very low loadings of S-POSS (1%). The presence of S-POSS has also improved the proton conductivity especially at low humidities, where it shows a marked increase due to its confinement in the ionic domains and promotes water uptake by capillary condensation. In order to achieve anhydrous conductivity, the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI-BTSI) was incorporated into these membranes to provide proton conduction in the absence of water. Although the incorporation of an IL shows a plasticizing effect on the Nafion membrane, the S-POSS composite membrane with an IL shows a higher modulus at high temperatures compared to Nafion 117 and a Nafion-IL membrane, with significantly higher proton conductivity (5 mS/cm at 150 degrees C with 20% IL). This shows the ability of the multifunctional POSS and IL to work symbiotically to achieve the desirable proton conductivity and mechanical properties of such membranes by enhancing the ionic interaction within the material.

  7. Styrene oligomerization as a molecular probe reaction for Brønsted acidity at the nanoscale.

    Science.gov (United States)

    Aramburo, Luis R; Wirick, Sue; Miedema, Piter S; Buurmans, Inge L C; de Groot, Frank M F; Weckhuysen, Bert M

    2012-05-21

    The Brønsted acid-catalyzed oligomerization of 4-fluorostyrene has been studied on a series of H-ZSM-5 zeolite powders, steamed under different conditions, with a combination of UV-Vis micro-spectroscopy and Scanning Transmission X-ray Microscopy (STXM). UV-Vis micro-spectroscopy and STXM have been used to monitor the relative formation of cyclic and linear dimeric carbocations as a function of the steaming post-treatment (i.e., parent vs. steaming at 600, 700 and 800 °C). It was found that the UV-Vis band intensity ratios of linear to cyclic dimeric species increase from 0.79 (parent H-ZSM-5) over 1.41 (H-ZSM-5 steamed at 600 °C) and 1.88 (H-ZSM-5 steamed at 700 °C) to 2.33 (H-ZSM-5 steamed at 800 °C). STXM confirms this trend in reaction product selectivity, as the relative intensities of the transitions attributed to the presence of the cyclic dimer in the carbon K-edge spectra decrease with increasing severity of the steaming post-treatment. Furthermore, STXM reveals spatial heterogeneities in reaction product formation within the H-ZSM-5 zeolite powders at the nanoscale. More specifically, a shrinking carbon core-shell distribution was detected within the zeolite aggregates, in which the relative amount of cyclic dimeric species is higher in the core relative to the shell of the zeolite aggregate and the relative amount of cyclic dimeric species in the zeolite core gradually decreases with increasing severity of the steaming post-treatment. These differences are rationalized in terms of spatial differences in Brønsted acidity within H-ZSM-5 zeolite powders as well as by changes in the formation process of linear and dimeric carbocations within H-ZSM-5 micro- and mesopores.

  8. Agents Play Mix-game

    CERN Document Server

    Gou, C

    2005-01-01

    In mix-game which is an extension of minority game, there are two groups of agents; group1 plays the majority game, but the group2 plays the minority game. This paper studies the change of the average winnings of agents and volatilities vs. the change of mixture of agents in mix-game model. It finds that the correlations between the average winnings of agents and the mean of local volatilities are different with different combinations of agent memory length when the proportion of agents in group 1 increases. This study result suggests that memory length of agents in group1 be smaller than that of agent in group2 when mix-game model is used to simulate the financial markets.

  9. Playing Business "Ball" with Cuba

    Institute of Scientific and Technical Information of China (English)

    Yang Wei; Gong Liming

    2007-01-01

    @@ If you were lucky enough to have seen the World Volleyball Tournament,you must have seen the Cuban Women's volleyball team take on China in the championship game,a game of which Cuba has become the world champion for 10 times.The great determination and strong tenacity of these young Cuban girls' has been an encouragement to everyone that watches them play.

  10. Cysteine mutagenesis reveals alternate proximity between transmembrane domain 2 and hairpin loop 1 of the glutamate transporter EAAT1.

    Science.gov (United States)

    Zhang, Yunlong; Zhang, Xiuping; Qu, Shaogang

    2014-07-01

    Excitatory amino acid transporter 1 (EAAT1) plays an important role in restricting the neurotoxicity of glutamate. Previous structure-function studies have provided evidence that reentrant helical hairpin loop (HP) 1 has predominant function during the transport cycle. The proposed internal gate HP1 is packed against transmembrane domain (TM) 2 and TM5 in its closed state, and two residues located in TM2 and HP2 of EAAT1 are in close proximity. However, the spatial relationship between TM2 and HP1 during the transport cycle remains unknown. In this study, we used chemical cross-linking of introduced cysteine pair (V96C and S366C) in a cysteine-less version of EAAT1 to assess the proximity of TM2 and HP1. Here, we show that inhibition of transport by copper(II)(1,10-phenanthroline)3 (CuPh) and cadmium ion (Cd(2+)) were observed in the V96C/S366C mutant. Glutamate or potassium significantly protected against the inhibition of transport activity of V96C/S366C by CuPh, while TBOA potentiated the inhibition of transport activity of V96C/S366C by CuPh. We also checked the kinetic parameters of V96C/S366C treated with or without CuPh in the presence of NaCl, NaCl + L-glutamate, NaCl + TBOA, and KCl, respectively. The sensitivity of V96C and S366C to membrane-impermeable sulfhydryl reagent MTSET [(2-trimethylammonium) methanethiosulfonate] was attenuated by glutamate or potassium. TBOA had no effect on the sensitivity of V96C and S366C to MTSET. These data suggest that the spatial relationship between Val-96 of TM2 and Ser-366 of HP1 is altered in the transport cycle.

  11. Playing Moderately Hard to Get

    Directory of Open Access Journals (Sweden)

    Stephen Reysen

    2013-12-01

    Full Text Available In two studies, we examined the effect of different degrees of attraction reciprocation on ratings of attraction toward a potential romantic partner. Undergraduate college student participants imagined a potential romantic partner who reciprocated a low (reciprocating attraction one day a week, moderate (reciprocating attraction three days a week, high (reciprocating attraction five days a week, or unspecified degree of attraction (no mention of reciprocation. Participants then rated their degree of attraction toward the potential partner. The results of Study 1 provided only partial support for Brehm’s emotion intensity theory. However, after revising the high reciprocation condition vignette in Study 2, supporting Brehm’s emotion intensity theory, results show that a potential partners’ display of reciprocation of attraction acted as a deterrent to participants’ intensity of experienced attraction to the potential partner. The results support the notion that playing moderately hard to get elicits more intense feelings of attraction from potential suitors than playing too easy or too hard to get. Discussion of previous research examining playing hard to get is also re-examined through an emotion intensity theory theoretical lens.

  12. Prolonged exposure of cortical neurons to oligomeric amyloid-β impairs NMDA receptor function via NADPH oxidase-mediated ROS production: protective effect of green tea (–-epigallocatechin-3-gallate

    Directory of Open Access Journals (Sweden)

    Grace Y Sun

    2011-02-01

    Full Text Available Excessive production of Aβ (amyloid β-peptide has been shown to play an important role in the pathogenesis of AD (Alzheimer's disease. Although not yet well understood, aggregation of Aβ is known to cause toxicity to neurons. Our recent study demonstrated the ability for oligomeric Aβ to stimulate the production of ROS (reactive oxygen species in neurons through an NMDA (N-methyl-d-aspartate-dependent pathway. However, whether prolonged exposure of neurons to aggregated Aβ is associated with impairment of NMDA receptor function has not been extensively investigated. In the present study, we show that prolonged exposure of primary cortical neurons to Aβ oligomers caused mitochondrial dysfunction, an attenuation of NMDA receptor-mediated Ca2+ influx and inhibition of NMDA-induced AA (arachidonic acid release. Mitochondrial dysfunction and the decrease in NMDA receptor activity due to oligomeric Aβ are associated with an increase in ROS production. Gp91ds-tat, a specific peptide inhibitor of NADPH oxidase, and Mn(III-tetrakis(4-benzoic acid-porphyrin chloride, an ROS scavenger, effectively abrogated Aβ-induced ROS production. Furthermore, Aβ-induced mitochondrial dysfunction, impairment of NMDA Ca2+ influx and ROS production were prevented by pre-treatment of neurons with EGCG [(−-epigallocatechin-3-gallate], a major polyphenolic component of green tea. Taken together, these results support a role for NADPH oxidase-mediated ROS production in the cytotoxic effects of Aβ, and demonstrate the therapeutic potential of EGCG and other dietary polyphenols in delaying onset or retarding the progression of AD.

  13. Spontaneous Activation of Antigen-presenting Cells by Genes Encoding Truncated Homo-Oligomerizing Derivatives of CD40.

    Science.gov (United States)

    Levin, Noam; Pato, Aviad; Cafri, Gal; Eisenberg, Galit; Peretz, Tamar; Margalit, Alon; Lotem, Michal; Gross, Gideon

    The interaction between the CD40 receptor on antigen-presenting cells (APCs) and its trimeric ligand on CD4 T cells is essential for the initiation and progression of the adaptive immune response. Here we undertook to endow CD40 with the capacity to trigger spontaneous APC activation through ligand-independent oligomerization. To this end we exploited the GCN4 yeast transcriptional activator, which contains a leucine zipper DNA-binding motif that induces homophilic interactions. We incorporated GCN4 variants forming homodimers, trimers, or tetramers at the intracellular domain of human and mouse CD40 and replaced the extracellular portion with peptide-β2m or other peptide tags. In parallel we examined similarly truncated CD40 monomers lacking a GCN4 motif. The oligomeric products appeared to arrange in high-molecular-weight aggregates and were considerably superior to the monomer in their ability to trigger nuclear factor kB signaling, substantiating the anticipated constitutively active (ca) phenotype. Cumulative results in human and mouse APC lines transfected with caCD40 mRNA revealed spontaneous upregulation of CD80, IL-1β, TNFα, IL-6, and IL-12, which could be further enhanced by caTLR4 mRNA. In mouse bone-marrow-derived dendritic cells caCD40 upregulated CD80, CD86, MHC-II, and IL-12 and in human monocyte-derived dendritic cells it elevated surface CD80, CD83 CD86, CCR7, and HLA-DR. Oligomeric products carrying the peptide-β2m extracellular portion could support MHC-I presentation of the linked peptide up to 4 days post-mRNA transfection. These findings demonstrate that the expression of a single caCD40 derivative in APCs can exert multiple immunostimulatory effects, offering a new powerful tool in the design of gene-based cancer vaccines.

  14. BRET and Time-resolved FRET strategy to study GPCR oligomerization: from cell lines toward native tissues

    Directory of Open Access Journals (Sweden)

    Martin eCottet

    2012-07-01

    Full Text Available The concept of oligomerization of G protein-coupled receptor (GPCR opens new perspectives regarding physiological function regulation. The capacity of one GPCR to modify its binding and coupling properties by interacting with a second one can be at the origin of regulations unsuspected two decades ago. Although the concept is interesting, its validation at a physiological level is challenging and probably explains why receptor oligomerization is still a matter of debate.Demonstrating the direct interactions between two proteins is not trivial since few techniques present a spatial resolution allowing to conclude to close interactions. Resonance energy transfer (RET strategies are actually the most convenient ones. During the last two decades, two of them, the Bioluminescent Resonance Energy Transfer (BRET and Time-resolved Fluorescence Energy Transfer (TR-FRET have been widely used since they exhibit high signal-to-noise ratio. Most of the experiments based on GPCR labeling have been performed in cell lines and it has been shown that all GPCRs have the propensity to form homo- or hetero-oligomers. However, whether these data can be extrapolated to GPCRs expressed in native tissues and explain receptor functioning in real life, remains an open question. Native tissues impose different constraints since GPCR sequences cannot be modified. Recently a fluorescent ligand-based GPCR labeling strategy combined to TR-FRET approach has been successfully used to prove the existence of GPCR oligomerization in native tissues.Although the RET based strategies are generally quite simple to implement, precautions have to be taken before concluding to the absence or the existence of specific interactions between receptors. For example, one should exclude the possibility of collision of receptors diffusing throughout the membrane leading to a specific FRET signal. We will review the advantages and the limits of different approaches and discuss the consequent

  15. Synthesis and characterization of polyhedral oligomeric titanized silsesquioxane: A new biocompatible cage like molecule for biomedical application

    Energy Technology Data Exchange (ETDEWEB)

    Yahyaei, Hossein [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Mohseni, Mohsen, E-mail: mmohseni@aut.ac.ir [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of); Ghanbari, Hossein [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences (TUMS), Tehran (Iran, Islamic Republic of); Messori, Massimo [Dipartimento di Ingegneria ‘Enzo Ferrari’, Università di Modena e Reggio Emilia, Modena (Italy)

    2016-04-01

    Organic–inorganic hybrid materials have shown improved properties to be used as biocompatible coating in biomedical applications. Polyhedral oligomeric silsesquioxane (POSS) containing coatings are among hybrid materials showing promising properties for these applications. In this work an open cage POSS has been reacted with a titanium alkoxide to end cap the POSS molecule with titanium atom to obtain a so called polyhedral oligomeric metalized silsesquioxane (POMS). The synthesized POMS was characterized by FTIR, RAMAN and UV–visible spectroscopy as well as {sup 29}Si NMR and matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) techniques. Appearance of peaks at 920 cm{sup −1} in FTIR and 491 cm{sup −1} and 1083 cm{sup −1} in Raman spectra confirmed Si–O–Ti linkage formation. It was also demonstrated that POMS was in a monomeric form. To evaluate the biocompatibility of hybrids films, pristine POSS and synthesized POMS were used in synthesis of a polycarbonate urethane polymer. Results revealed that POMS containing hybrid, not only had notable thermal and mechanical stability compared to POSS containing one, as demonstrated by DSC and DMTA analysis, they also showed controlled surface properties in such a manner that hydrophobicity and biocompatibility were both reachable to give rise to improved cell viability in presence of human umbilical vein endothelial cells (HUVEC) and MRC-5 cells. - Highlight: • Polyhedral Oligomeric Metalized Silsesquioxane (POMS) based on titanium was synthesized. • POMS can improve mechanical properties of polyurethane. • POMS increases hydrophobicity of polyurethane. • POMS is a unique nanocage to enhance biocompatibility of polyurethane.

  16. Attempted nonenzymatic template-directed oligomerizations on a polyadenylic acid template: implications for the nature of the first genetic material

    Science.gov (United States)

    Stribling, R.; Miller, S. L.

    1991-01-01

    Previous attempts to produce nonenzymatic template-directed oligomerizations of activated pyrimidines on polypurine templates have been unsuccessful. The only efficient reactions are those where the template is composed primarily of pyrimidines, especially cytosine. Because molecular evolution requires that a synthesized daughter polynucleotide be capable of acting as a template for the synthesis of the original polynucleotide, the one-way replication achieved thus far is inadequate to initiate an evolving system. Several uracil analogs were used in this investigation in order to search for possible replacements for uracil. The monomers used in this investigation were the imidazolides of UMP, xanthosine 5'-monophosphate, the bis-monophosphates of the acyclic nucleosides of uracil, and 2,4-quinazolinedione. The concentrations of various salts, buffers, pH, and temperature were among the different variables investigated in attempts to find conditions that would permit template-directed oligomerizations. Although the different monomers in this study demonstrated varying abilities to form very short oligomers, we were unable to detect any enhancement of this oligomerization that could be attributed to the poly(A) template. Although special conditions might be found that would allow purine-rich templates to work, these reactions cannot be considered robust. The results of our experiments suggest that pyrimidines were not part of the original replicating system on the primitive Earth. It has already been shown that ribose is an unlikely component of the first replicating systems, and we now suggest that phosphate was absent as well. This is due to the low solubility of phosphate in the present ocean (3 x 10(-6) M), as well as the difficulty of prebiotic activation of phosphates.

  17. Large-scale identification of coevolution signals across homo-oligomeric protein interfaces by direct coupling analysis.

    Science.gov (United States)

    Uguzzoni, Guido; John Lovis, Shalini; Oteri, Francesco; Schug, Alexander; Szurmant, Hendrik; Weigt, Martin

    2017-03-28

    Proteins have evolved to perform diverse cellular functions, from serving as reaction catalysts to coordinating cellular propagation and development. Frequently, proteins do not exert their full potential as monomers but rather undergo concerted interactions as either homo-oligomers or with other proteins as hetero-oligomers. The experimental study of such protein complexes and interactions has been arduous. Theoretical structure prediction methods are an attractive alternative. Here, we investigate homo-oligomeric interfaces by tracing residue coevolution via the global statistical direct coupling analysis (DCA). DCA can accurately infer spatial adjacencies between residues. These adjacencies can be included as constraints in structure prediction techniques to predict high-resolution models. By taking advantage of the ongoing exponential growth of sequence databases, we go significantly beyond anecdotal cases of a few protein families and apply DCA to a systematic large-scale study of nearly 2,000 Pfam protein families with sufficient sequence information and structurally resolved homo-oligomeric interfaces. We find that large interfaces are commonly identified by DCA. We further demonstrate that DCA can differentiate between subfamilies with different binding modes within one large Pfam family. Sequence-derived contact information for the subfamilies proves sufficient to assemble accurate structural models of the diverse protein-oligomers. Thus, we provide an approach to investigate oligomerization for arbitrary protein families leading to structural models complementary to often-difficult experimental methods. Combined with ever more abundant sequential data, we anticipate that this study will be instrumental to allow the structural description of many heteroprotein complexes in the future.

  18. Mechanical property and thermal stability of polyurethane composites reinforced with polyhedral oligomeric silsesquioxanes and inorganic flame retardant filler.

    Science.gov (United States)

    Kim, Ho-Joong; Kwon, Younghwan; Kim, Chang Kee

    2014-08-01

    Mechanical properties and thermal stability of polyurethane composites were investigated with a combination of polyhedral oligomeric silsesquioxane (POSS) molecules and inorganic barium sulfate. These hybrid composites were prepared using one-step method through the incorporation of flexible hydroxyl-terminated polybutadiene prepolymer, reactive POSS nanoparticles, and barium sulfate under isophorone diisocyanate curative system. In polyurethane composites, POSS and inorganic barium sulfate were utilized for mechanical reinforcement and flame retardant filler, respectively. The decomposition of POSS molecules during oxyacetylene torch exposure resulted in the formation of silica-based nanosized droplets, contributing on ablation behavior.

  19. An enigmatic peptide ligation reaction: protease-catalyzed oligomerization of a native protein segment in neat aqueous solution.

    Science.gov (United States)

    Kumaran, S; Datta, D; Roy, R P

    2000-04-01

    We report an enigmatic peptide ligation reaction catalyzed by Glu-specific Staphylococcus aureus V8 protease that occurs in neat aqueous solution around neutral pH utilizing a totally unprotected peptide substrate containing free alpha-carboxyl and alpha-amino groups. V8 protease catalyzed a chain of ligation steps between pH 6 and 8 at 4 degrees C, producing a gamut of covalent oligomers (dimer through octamer or higher) of a native protein segment TAAAKFE (S39) derived from ribonuclease A (RNAse A). Size-exclusion chromatography suggested the absence of strong interaction between the reacting peptides. The circular dichroism spectra of monomer through pentamer showed length-dependent enhancement of secondary structure in the oligomers, suggesting that protease-catalyzed ligation of a monomer to an oligomer resulted in a product that was more structured than its precursor. The relative conformational stability of the oligomers was reflected in their ability to resist proteolysis, indicating that the oligomerization reaction was facilitated as a consequence of the "conformational trapping" of the product. The ligation reaction proceeded in two phases-slow formation and accumulation of the dimer followed by a fast phase of oligomerization, implying that the conformational trap encountered in the oligomerization reaction was a two-step process. The Gly substitution at any position of the TAAAKFE sequence was deleterious, suggesting that the first step of the conformational trap, namely the dimerization reaction, that proceeded very slowly even with the parent peptide, was quite sensitive to amino acid sequence. In contrast, the oligomerization reaction of an Ala analog, AAAAKFE, occurred in much the same way as S39, albeit with faster rate, suggesting that Ala substitution stabilized the overall conformational trapping process. The results suggest the viability of the product-directed "conformational trap" as a mechanism to achieve peptide ligation of totally

  20. On the simulation of enzymatic digest patterns: the fragmentation of oligomeric and polymeric galacturonides by endo-polygalacturonase II

    CERN Document Server

    Hunt, J J; Williams, M A K; Hunt, Jonathan J; Cameron, Randall G; Williams, Martin A.K.

    2006-01-01

    A simulation methodology for predicting the time-course of enzymatic digestions is described. The model is based solely on the enzyme's subsite architecture and concomitant binding energies. This allows subsite binding energies to be used to predict the evolution of the relative amounts of different products during the digestion of arbitrary mixtures of oligomeric or polymeric substrates. The methodology has been specifically demonstrated by studying the fragmentation of a population of oligogalacturonides of varying degrees of polymerization, when digested by endo-polygalacturonase II (endo-PG II) from Aspergillus niger.

  1. Transition metal complexes bearing 2,6-bis(imino)pyridyl:Synthesis, structure, ethylene polymerization/oligomerization studies

    Institute of Scientific and Technical Information of China (English)

    SU; Biyun; ZHAO; Jianshe; SUN; Wenhua

    2005-01-01

    A series of new complexes {2,6-bis[1-((2-methyl-4-methoxyphenyl)imino)ethyl]pyridine}MCI2 [M=Fe(Ⅱ) (2), Co(Ⅱ) (3), Ni(Ⅱ) (4), Cu(Ⅱ) (5), Zn(Ⅱ) (6)] have been synthesized. At 25℃, using 500 equiv of methylaluminoxane (MAO), the activities of Fe(Ⅱ), Co(Ⅱ) catalysts can ethylene oligomerization. The effects of polymerization conditions such as reaction temperature,AI/M molar ratio and time on the activity of catalyst have been explored.

  2. A New Star-shaped Carbazole Derivative with Polyhedral Oligomeric Silsesquioxane Core: Crystal Structure and Unique Photoluminescence Property.

    Science.gov (United States)

    Xu, Zixuan; Yu, Tianzhi; Zhao, Yuling; Zhang, Hui; Zhao, Guoyun; Li, Jianfeng; Chai, Lanqin

    2016-01-01

    A new inorganic–organic hybrid material based on polyhedral oligomeric silsesquioxane (POSS) capped with carbazolyl substituents, octakis[3-(carbazol-9-yl)propyldimethylsiloxy]-silsesquioxane (POSS-8Cz), was successfully synthesized and characterized. The X-ray crystal structure of POSS-8Cz were described. The photophysical properties of POSS-8Cz were investigated by using UV–vis,photoluminescence spectroscopic analysis. The hybrid material exhibits blue emission in the solution and the solid film.The morphology and thermal stablity properties were measured by X-ray diffraction (XRD) and TG-DTA analysis.

  3. In situ oligomerization of 2-(thiophen-3-yl)acetate intercalated into Zn{sub 2}Al layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Tronto, Jairo, E-mail: jairotronto@ufv.br [Universidade Federal de Viçosa, Instituto de Ciências Exatas e Tecnológicas, Campus de Rio Parsanaíba, Rodovia BR 354 km 310, Cx. Postal 22, CEP, 38.810-000 Rio Paranaíba, MG (Brazil); Pinto, Frederico G.; Costa, Liovando M. da [Universidade Federal de Viçosa, Instituto de Ciências Exatas e Tecnológicas, Campus de Rio Parsanaíba, Rodovia BR 354 km 310, Cx. Postal 22, CEP, 38.810-000 Rio Paranaíba, MG (Brazil); Leroux, Fabrice; Dubois, Marc [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, ICCF, BP 80026, F-6317 Clermont-Ferrand (France); Valim, João B. [Universidade de São Paulo, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Departamento de Química, Av. dos Bandeirantes 3900, CEP 14.040-901, Ribeirão Preto, SP (Brazil)

    2015-01-15

    A layered double hydroxide (LDH) with cation composition Zn{sub 2}Al was intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers. To achieve in situ polymerization and/or oligomerization of the intercalated monomers, soft thermal treatments were carried out, and subsequent hybrid LDH materials were analyzed by means of several characterization techniques using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), {sup 13}C CP–MAS nuclear magnetic resonance (NMR), electron spin resonance (EPR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP–OES), and elemental analysis. PXRD analysis suggested that the intercalated monomers formed a bilayer. Thermal treatment of the hybrid LDH assembly above 120 °C provokes partially the breakdown of the layered structure, generating the phase zincite. EPR results indicated that vicinal monomers (oligomerization) were bound to each other after hydrothermal or thermal treatment, leading to a polaron response characteristic of electron conductivity localized on a restricted number of thiophene-based monomer segments. Localized unpaired electrons exist in the material and interact with the {sup 27}Al nuclei of the LDH layers by superhyperfine coupling. These unpaired electrons also interact with the surface of ZnO (O{sup 2−} vacancies), formed during the thermal treatments. - Graphical abstract: We synthesized a layered double hydroxide (LDH) with cation composition Zn{sub 2}Al, intercalated with 2-(thiophen-3-yl)acetate (3-TA) monomers, by coprecipitation at constant pH. We thermally treated the material, to achieve in situ polymerization and/or oligomerization of the intercalated monomers. - Highlights: • A Zn{sub 2}Al–LDH was intercalated with 2-(thiophen-3-yl)acetate monomers. • To achieve in situ oligomerization of the monomers, thermal treatments were made.

  4. Functionalization of polyhedral oligomeric silsesquioxanes with bis(hydroxyethyl) ester and preparation of the corresponding degradable nanohybrids

    Institute of Scientific and Technical Information of China (English)

    Bing Tao Wang; Yan Zhang; Ping Zhang; Zheng Ping Fang

    2012-01-01

    One novel difunctionalized polyhedral oligomeric silsesquioxanes (POSS) derivative was designed and synthesized by a convenient method with high yield.1H NMR and FT-IR characterizations suggested that Michael addition reaction successfully took place between 2-hydroxyethyl acrylate (HEA) and aminopropylisobutyl POSS (POSS-NH2) under mild conditions,which finally formed bi(hydroxyethyl) ester-functionalized POSS derivatives (BH-POSS).Due to the similar functional groups and high reactivity,BH-POSS could be easily incorporated into the main-chain of biodegradable aliphatic-aromatic copolyesters PBTL via in situ melt polycondensation to prepare corresponding degradable nanohybrids with high mechanical properties.

  5. Jakob Kelemina on Shakespeare's plays

    Directory of Open Access Journals (Sweden)

    Mirko Jurak

    2007-12-01

    Full Text Available Among Slovene scholars in English and German studies Jakob Kelemina (19 July 1882- 14 May 1957 has a very important  place. Janez Stanonik justly places him among the founding fathers of the University of Ljubljana (Stanonik 1966: 332. From 1920 Kelemina was professor of Germanic philology and between 1920 and 1957 he was also the Chair of the Deparment ofGermanic Languages and Literatures at the Faculty of Arts of this university. The major part of Kelemina's research was devoted to German and Austrian literatures,  German  philology, German-Slovene cultural relations, and literary theory; his work in these fields has already been discussed  by severa! Slovene scholars. However, in the first two decades of the twentieth century Kelemina also wrote severa! book reviews of Slovene and Croatian translations of Shakespeare's plays as well as three introductory essays to Slovene translations  of Shakespeare's plays. They are considered  as the first serious studies on Shakespeare in Slovenia (Moravec 1974: 437, and have not been analysed yet. Therefore this topic presents the core of my study, together with an evaluation  of Kelemina's contribution  to Slovene translations  of Shakespeare's plays done by Oton Župančič (1878-1949 during the first half of the twentieth century. Župančič's translations  became the criterion  for all further translations  of Shakespeare's dramatic works in Slovene. Župančič is stili one of our most important  poets and translators of this time and Kelemina's advice and criticism undoubtedly  also helped him to achieve such a high standard in his translations. In the central part of my study I also include some new material (e.g. Kelernina's letters, which is relevant for our understanding  of his co-operation with Oton Župančič  and other Slovene authors and critics. In order to put Kelemina's work into a historical perspective I present at the beginning of my study a brief survey of the

  6. Playing Children Adorn Ancient Porcelain

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    Porcelain is one of China’s greatest achievernents. It appeared during the Eastern Han Dynasty (25-220) and developed into three types of blue porcelain, white porcelain and colored porcelain between the Tang and Song dynasties. From the time of the Ming Dynasty (1368-1644), porcelain-making evolved, glazes and colors improved and porcelain was sold overseas. The quaint shapes and colorfully deslgned porcelain of the Ming Dynasty showed the appeal of folklife, but it was mainly used in the palace. Shown here are some pieces decorated with children at play. From these artifacts we can get an idea of the hairstyles, dress and architecture of that time.

  7. How to play Reverse Hex

    DEFF Research Database (Denmark)

    Toft, Bjarne; Hayward, Ryan B.; Henderson, Philip

    2012-01-01

    We present new results on how to play Reverse Hex, also known as Rex, or Misère Hex, on n × n boards. We give new proofs – and strengthened versions – of Lagarias and Sleator’s theorem (for n × n boards, each player can prolong the game until the board is full, so the first/second player can always......, we find second-player winning replies. Finally, in response to comments by Martin Gardner, for each n ≤ 5, we give a simple winning strategy for the n × n board....

  8. Supervising the uncanny: the play within the play.

    Science.gov (United States)

    Leader, Carol

    2015-11-01

    The writer offers a combined experience in analysis and the performing arts to explore uncanny aspects of the unconscious subtext of the patient's inner drama; subtext which can remain hidden from view in supervision. Freud and Jung's understanding of uncanny experience is considered together with a painting from medieval alchemy and Matte Blanco's conceptions concerning the symmetrical nature of unconscious process. Theatre and the work of the theatre director and actor in approaching the multidimensional aspects of a play are then introduced. Finally clinical case material from group supervision demonstrates how the 'theatre of therapy' and the work of the supervisory couple and group promote the emergence of a more authentic conscious asymmetrical response to the patient's 'script' that can break the 'spell' of the transference/countertransference relationship. This in turn brings meaning to the underlying and implicit 'stage directions' that the patient has been unconsciously communicating. © 2015, The Society of Analytical Psychology.

  9. Playing Games with Quantum Mechanics

    CERN Document Server

    Phoenix, Simon J D

    2012-01-01

    We present a perspective on quantum games that focuses on the physical aspects of the quantities that are used to implement a game. If a game is to be played, it has to be played with objects and actions that have some physical existence. We call such games playable. By focusing on the notion of playability for games we can more clearly see the distinction between classical and quantum games and tackle the thorny issue of what it means to quantize a game. The approach we take can more properly be thought of as gaming the quantum rather than quantizing a game and we find that in this perspective we can think of a complete quantum game, for a given set of preferences, as representing a single family of quantum games with many different playable versions. The versions of Quantum Prisoners Dilemma presented in the literature can therefore be thought of specific instances of the single family of Quantum Prisoner's Dilemma with respect to a particular measurement. The conditions for equilibrium are given for playab...

  10. Predicting success of oligomerized pool engineering (OPEN for zinc finger target site sequences

    Directory of Open Access Journals (Sweden)

    Goodwin Mathew J

    2010-11-01

    Full Text Available Abstract Background Precise and efficient methods for gene targeting are critical for detailed functional analysis of genomes and regulatory networks and for potentially improving the efficacy and safety of gene therapies. Oligomerized Pool ENgineering (OPEN is a recently developed method for engineering C2H2 zinc finger proteins (ZFPs designed to bind specific DNA sequences with high affinity and specificity in vivo. Because generation of ZFPs using OPEN requires considerable effort, a computational method for identifying the sites in any given gene that are most likely to be successfully targeted by this method is desirable. Results Analysis of the base composition of experimentally validated ZFP target sites identified important constraints on the DNA sequence space that can be effectively targeted using OPEN. Using alternate encodings to represent ZFP target sites, we implemented Naïve Bayes and Support Vector Machine classifiers capable of distinguishing "active" targets, i.e., ZFP binding sites that can be targeted with a high rate of success, from those that are "inactive" or poor targets for ZFPs generated using current OPEN technologies. When evaluated using leave-one-out cross-validation on a dataset of 135 experimentally validated ZFP target sites, the best Naïve Bayes classifier, designated ZiFOpT, achieved overall accuracy of 87% and specificity+ of 90%, with an ROC AUC of 0.89. When challenged with a completely independent test set of 140 newly validated ZFP target sites, ZiFOpT performance was comparable in terms of overall accuracy (88% and specificity+ (92%, but with reduced ROC AUC (0.77. Users can rank potentially active ZFP target sites using a confidence score derived from the posterior probability returned by ZiFOpT. Conclusion ZiFOpT, a machine learning classifier trained to identify DNA sequences amenable for targeting by OPEN-generated zinc finger arrays, can guide users to target sites that are most likely to function

  11. Glutathione mediated regulation of oligomeric structure and functional activity of Plasmodium falciparum glutathione S-transferase

    Directory of Open Access Journals (Sweden)

    Becker Katja

    2007-10-01

    Full Text Available Abstract Background In contrast to many other organisms, the malarial parasite Plasmodium falciparum possesses only one typical glutathione S-transferase. This enzyme, PfGST, cannot be assigned to any of the known GST classes and represents a most interesting target for antimalarial drug development. The PfGST under native conditions forms non-covalently linked higher aggregates with major population (~98% being tetramer. However, in the presence of 2 mM GSH, a dimer of PfGST is observed. Recently reported study on binding and catalytic properties of PfGST indicated a GSH dependent low-high affinity transition with simultaneous binding of two GSH molecules to PfGST dimer suggesting that GSH binds to low affinity inactive enzyme dimer converting it to high affinity functionally active dimer. In order to understand the role of GSH in tetramer-dimer transition of PfGST as well as in modulation of functional activity of the enzyme, detailed structural, functional and stability studies on recombinant PfGST in the presence and absence of GSH were carried out. Results Our data indicate that the dimer – and not the tetramer – is the active form of PfGST, and that substrate saturation is directly paralleled by dissociation of the tetramer. Furthermore, this dissociation is a reversible process indicating that the tetramer-dimer equilibrium of PfGST is defined by the surrounding GSH concentration. Equilibrium denaturation studies show that the PfGST tetramer has significantly higher stability compared to the dimer. The enhanced stability of the tetramer is likely to be due to stronger ionic interactions existing in it. Conclusion This is the first report for any GST where an alteration in oligomeric structure and not just small conformational change is observed upon GSH binding to the enzyme. Furthermore we also demonstrate a reversible mechanism of regulation of functional activity of Plasmodium falciparum glutathione S-transferase via GSH induced

  12. Dispersion states and surface characteristics of physically blended polyhedral oligomeric silsesquioxane/polymer hybrid nanocomposites

    Science.gov (United States)

    Misra, Rahul

    Control of dispersion and segregation states of nanostructured additives is one of the biggest challenges in realizing the optimum potential of high performance hybrid polymer nanocomposites. Polyhedral oligomeric silsesquioxane (POSS) nanostructured chemicals, with their hybrid organic-inorganic nature and flexible functionalization with a variety of organic substituents, yield possibilities to control dispersion and tune compatibility in a wide range of polymer systems. The overall goal of this research is to investigate the fundamental parameters that influence the dispersion and segregation states of POSS nanostructured chemicals, and to understand chain dynamics and conformations in physically blended POSS hybrid polymer nanocomposites (HPNC's). Multiple structural and mechanical factors influencing macro to nano scale surface and bulk properties were successfully investigated and correlated. A strategy based on thermodynamic principles for selective control of POSS dispersion states in a given polymer matrix is developed and discussed. This dissertation consists of eight chapters. Chapter 1 provides a detailed introduction about the development and current research interest in POSS/polymer nanocomposites. This chapter also discusses limitations of current advanced nanoprobe techniques. Chapter 2 establishes the overall goal of this research and specific research ii objectives. Chapter 3 establishes the preferential surface migration behavior of physically dispersed, non-reactive, closed cage octaisobutyl POSS (Oib-POSS) in a non-polar polypropylene matrix. Furthermore, influence of POSS surface segregation on the surface properties, especially nano-tribomechanical behavior is also discussed. Chapter 4 expands the studies by melt blending two different types of POSS molecules, a non-reactive, closed cage Oib-POSS and an open cage trisilanolphenyl POSS (Tsp-POSS), in a nylon 6 matrix. This chapter discusses the morphology, nano-dispersion and macro- to

  13. Stable oligomeric clusters of gold nanoparticles: preparation, size distribution, derivatization, and physical and biological properties.

    Science.gov (United States)

    Smithies, Oliver; Lawrence, Marlon; Testen, Anze; Horne, Lloyd P; Wilder, Jennifer; Altenburg, Michael; Bleasdale, Ben; Maeda, Nobuyo; Koklic, Tilen

    2014-11-11

    Reducing dilute aqueous HAuCl4 with NaSCN under alkaline conditions produces 2-3 nm diameter yellow nanoparticles without the addition of extraneous capping agents. We here describe two very simple methods for producing highly stable oligomeric grape-like clusters (oligoclusters) of these small nanoparticles. The oligoclusters have well-controlled diameters ranging from ∼5 to ∼30 nm, depending mainly on the number of subunits in the cluster. Our first ["delay-time"] method controls the size of the oligoclusters by varying from seconds to hours the delay time between making the HAuCl4 alkaline and adding the reducing agent, NaSCN. Our second ["add-on"] method controls size by using yellow nanoparticles as seeds onto which varying amounts of gold derived from "hydroxylated gold", Na(+)[Au(OH4-x)Clx](-), are added-on catalytically in the presence of NaSCN. Possible reaction mechanisms and a simple kinetic model fitting the data are discussed. The crude oligocluster preparations have narrow size distributions, and for most purposes do not require fractionation. The oligoclusters do not aggregate after ∼300-fold centrifugal-filter concentration, and at this high concentration are easily derivatized with a variety of thiol-containing reagents. This allows rare or expensive derivatizing reagents to be used economically. Unlike conventional glutathione-capped nanoparticles of comparable gold content, large oligoclusters derivatized with glutathione do not aggregate at high concentrations in phosphate-buffered saline (PBS) or in the circulation when injected into mice. Mice receiving them intravenously show no visible signs of distress. Their sizes can be made small enough to allow their excretion in the urine or large enough to prevent them from crossing capillary basement membranes. They are directly visible in electron micrographs without enhancement, and can model the biological fate of protein-like macromolecules with controlled sizes and charges. The ease of

  14. [THE COMPARATIVE ANALYSIS OF LEVEL OF OLIGOMERIC MATRIX PROTEIN OF CARTILAGE IN BLOOD SERUM OF PATIENTS WITH DISEASES OF MUSCULO-SKELETAL SYSTEM].

    Science.gov (United States)

    Starodubtseva, L A; Vasilieva, L V

    2016-02-01

    The osteoarthritis and rheumatoid arthritis are considered as the most prevalent diseases in the structure of diseases of musculoskeletal system. The higher social significance of these nosologies dictates necessity of searching reliable cartilage biomarkers having diagnostic validity both in discerning degenerative alterations at early stage of disease of joints and in monitoring of treatment effectiveness. The content of oligomeric matrix protein of cartilage using ELISA was evaluated in blood serum ofpatients with secondary osteoarthritis under rheumatoid arthritis (n=248). The comparison of derived results was carried out using control groups. Within the framework of study relationship was evaluated between level of oligomeric matrix protein of cartilage in patients with secondary osteoarthritis under rheumatoid arthritis with values offunctional KOOS index. The analysis of derived results established trend to increasing of level of oligomeric matrix protein of cartilage in blood serum ofpatients with secondary osteoarthritis under rheumatoid arthritis as compared with control groups. The moderate correlation interdependence between cartilage biomarker and KOOS index.

  15. Play behaviours and play object preferences of young children with autistic disorder in a clinical play environment.

    Science.gov (United States)

    Dominguez, Anna; Ziviani, Jenny; Rodger, Sylvia

    2006-01-01

    Play is the primary occupation of childhood and provides a potentially powerful means of assessing and treating children with autistic disorder. This study utilized a cross-sectional comparison design to investigate the nature of play engagement in children with AD (n = 24), relative to typically developing children (n = 34) matched for chronological age. Play behaviours were recorded in a clinical play environment. Videotapes comprising 15 minutes of the children's spontaneous play behaviour were analysed using time-interval analysis. The particular play behaviours observed and play objects used were coded. Differences in play behaviours (p motivation.

  16. Hand kinematics of piano playing.

    Science.gov (United States)

    Furuya, Shinichi; Flanders, Martha; Soechting, John F

    2011-12-01

    Dexterous use of the hand represents a sophisticated sensorimotor function. In behaviors such as playing the piano, it can involve strong temporal and spatial constraints. The purpose of this study was to determine fundamental patterns of covariation of motion across joints and digits of the human hand. Joint motion was recorded while 5 expert pianists played 30 excerpts from musical pieces, which featured ∼50 different tone sequences and fingering. Principal component analysis and cluster analysis using an expectation-maximization algorithm revealed that joint velocities could be categorized into several patterns, which help to simplify the description of the movements of the multiple degrees of freedom of the hand. For the thumb keystroke, two distinct patterns of joint movement covariation emerged and they depended on the spatiotemporal patterns of the task. For example, the thumb-under maneuver was clearly separated into two clusters based on the direction of hand translation along the keyboard. While the pattern of the thumb joint velocities differed between these clusters, the motions at the metacarpo-phalangeal and proximal-phalangeal joints of the four fingers were more consistent. For a keystroke executed with one of the fingers, there were three distinct patterns of joint rotations, across which motion at the striking finger was fairly consistent, but motion of the other fingers was more variable. Furthermore, the amount of movement spillover of the striking finger to the adjacent fingers was small irrespective of the finger used for the keystroke. These findings describe an unparalleled amount of independent motion of the fingers.

  17. Nanomolar oligomerization and selective co-aggregation of α-synuclein pathogenic mutants revealed by single-molecule fluorescence

    Science.gov (United States)

    Sierecki, Emma; Giles, Nichole; Bowden, Quill; Polinkovsky, Mark E.; Steinbeck, Janina; Arrioti, Nicholas; Rahman, Diya; Bhumkar, Akshay; Nicovich, Philip R.; Ross, Ian; Parton, Robert G.; Böcking, Till; Gambin, Yann

    2016-01-01

    Protein aggregation is a hallmark of many neurodegenerative diseases, notably Alzheimer’s and Parkinson’s disease. Parkinson’s disease is characterized by the presence of Lewy bodies, abnormal aggregates mainly composed of α-synuclein. Moreover, cases of familial Parkinson’s disease have been linked to mutations in α-synuclein. In this study, we compared the behavior of wild-type (WT) α-synuclein and five of its pathological mutants (A30P, E46K, H50Q, G51D and A53T). To this end, single-molecule fluorescence detection was coupled to cell-free protein expression to measure precisely the oligomerization of proteins without purification, denaturation or labelling steps. In these conditions, we could detect the formation of oligomeric and pre-fibrillar species at very short time scale and low micromolar concentrations. The pathogenic mutants surprisingly segregated into two classes: one group forming large aggregates and fibrils while the other tending to form mostly oligomers. Strikingly, co-expression experiments reveal that members from the different groups do not generally interact with each other, both at the fibril and monomer levels. Together, this data paints a completely different picture of α-synuclein aggregation, with two possible pathways leading to the development of fibrils. PMID:27892477

  18. Nanomolar oligomerization and selective co-aggregation of α-synuclein pathogenic mutants revealed by single-molecule fluorescence.

    Science.gov (United States)

    Sierecki, Emma; Giles, Nichole; Bowden, Quill; Polinkovsky, Mark E; Steinbeck, Janina; Arrioti, Nicholas; Rahman, Diya; Bhumkar, Akshay; Nicovich, Philip R; Ross, Ian; Parton, Robert G; Böcking, Till; Gambin, Yann

    2016-11-28

    Protein aggregation is a hallmark of many neurodegenerative diseases, notably Alzheimer's and Parkinson's disease. Parkinson's disease is characterized by the presence of Lewy bodies, abnormal aggregates mainly composed of α-synuclein. Moreover, cases of familial Parkinson's disease have been linked to mutations in α-synuclein. In this study, we compared the behavior of wild-type (WT) α-synuclein and five of its pathological mutants (A30P, E46K, H50Q, G51D and A53T). To this end, single-molecule fluorescence detection was coupled to cell-free protein expression to measure precisely the oligomerization of proteins without purification, denaturation or labelling steps. In these conditions, we could detect the formation of oligomeric and pre-fibrillar species at very short time scale and low micromolar concentrations. The pathogenic mutants surprisingly segregated into two classes: one group forming large aggregates and fibrils while the other tending to form mostly oligomers. Strikingly, co-expression experiments reveal that members from the different groups do not generally interact with each other, both at the fibril and monomer levels. Together, this data paints a completely different picture of α-synuclein aggregation, with two possible pathways leading to the development of fibrils.

  19. Fingolimod phosphate attenuates oligomeric amyloid β-induced neurotoxicity via increased brain-derived neurotrophic factor expression in neurons.

    Directory of Open Access Journals (Sweden)

    Yukiko Doi

    Full Text Available The neurodegenerative processes that underlie Alzheimer's disease are mediated, in part, by soluble oligomeric amyloid β, a neurotoxic protein that inhibits hippocampal long-term potentiation, disrupts synaptic plasticity, and induces the production of reactive oxygen species. Here we show that the sphingosine-1-phosphate (S1P receptor (S1PR agonist fingolimod phosphate (FTY720-P-a new oral drug for multiple sclerosis-protects neurons against oligomeric amyloid β-induced neurotoxicity. We confirmed that primary mouse cortical neurons express all of the S1P receptor subtypes and FTY720-P directly affects the neurons. Treatment with FTY720-P enhanced the expression of brain-derived neurotrophic factor (BDNF in neurons. Moreover, blocking BDNF-TrkB signaling with a BDNF scavenger, TrkB inhibitor, or ERK1/2 inhibitor almost completely ablated these neuroprotective effects. These results suggested that the neuroprotective effects of FTY720-P are mediated by upregulated neuronal BDNF levels. Therefore, FTY720-P may be a promising therapeutic agent for neurodegenerative diseases, such as Alzheimer's disease.

  20. Application of MALDI-TOF mass spectrometry for study on fibrillar and oligomeric aggregates of alpha-synuclein

    Directory of Open Access Journals (Sweden)

    Severinovskaya O. V.

    2014-05-01

    Full Text Available Aim. To study the -synuclein (ASN aggregates of different structural origin, namely amyloid fibrils and spherical oligomers, in comparison with a native protein. Methods. MALDI TOF mass spectrometry and atomic for- ce microscopy (AFM. Results. The mass spectra of native and fibrillar ASN have similar character, i. e. they are characterized by the well pronounced peak of protein molecular ion, the low molecular weight associates, and rather low contain of fragmentation products. The spectrum of oligomeric aggregate is characterized by the high contain of fragmentation products, low intensity of protein molecular ion and the absence of peaks of associates. Conclusions. The difference between the spectra of fibrillar and oligomeric ASN could be explained, first, by the different content of the «residual» monomeric ASN and the protein degradation products in the studied samples, and, second, by the different structure-depended mechanisms of the protein degradation induced by the laser ionization. We suggested that the MALDI-TOF mass spectroscopy is a method useful for the investigation of ASN aggregation and characterization of its high order self-associates; besides, there is an interest in estimating the potency of the MALDI-TOF for the analysis of aggregation of various amyloidogenic proteins.