938 resultados para Collaborative Group


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In an attempt to identify the arginine residue involved in binding of the carboxylate group of serine to mammalian serine hydroxymethyltransferase, a highly conserved Arg-401 was mutated to Ala by site-directed mutagenesis. The mutant enzyme had a characteristic visible absorbance at 425 nm indicative of the presence of bound pyridoxal 5'-phosphate as an internal aldimine with a lysine residue. However, it had only 0.003% of the catalytic activity of the wild-type enzyme. It was also unable to perform reactions with glycine, beta-phenylserine or d-alanine, suggesting that the binding of these substrates to the mutant enzyme was affected. This was also evident from the interaction of amino-oxyacetic acid, which was very slow (8.4x10(-4) s-1 at 50 microM) for the R401A mutant enzyme compared with the wild-type enzyme (44.6 s-1 at 50 microM). In contrast, methoxyamine (which lacks the carboxy group) reacted with the mutant enzyme (1.72 s-1 at 250 microM) more rapidly than the wild-type enzyme (0.2 s-1 at 250 microM). Further, both wild-type and the mutant enzymes were capable of forming unique quinonoid intermediates absorbing at 440 and 464 nm on interaction with thiosemicarbazide, which also does not have a carboxy group. These results implicate Arg-401 in the binding of the substrate carboxy group. In addition, gel-filtration profiles of the apoenzyme and the reconstituted holoenzyme of R401A and the wild-type enzyme showed that the mutant enzyme remained in a tetrameric form even when the cofactor had been removed. However, the wild-type enzyme underwent partial dissociation to a dimer, suggesting that the oligomeric structure was rendered more stable by the mutation of Arg-401. The increased stability of the mutant enzyme was also reflected in the higher apparent melting temperature (Tm) (61 degrees C) than that of the wild-type enzyme (56 degrees C). The addition of serine or serinamide did not change the apparent Tm of R401A mutant enzyme. These results suggest that the mutant enzyme might be in a permanently 'open' form and the increased apparent Tm could be due to enhanced subunit interactions.

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Background & objectives: Group A Streptococcus, causative agent of several clinical manifestations codes for multiple protein invasins which help the bacterium to enter non-phagocytic cells. C5a peptidase (SCPA) is a surface protein conserved among different serotypes of M1 strain. The present study was taken up to study SCPA promoted fibronectin independent entry of GAS into epithelial cells. Methods: An isogenic 90226 emm1DeltaAB (M1(-)) mutant was constructed, with thermosensitive pGhost vector. This isogenic M1(-) mutant expressed SCPA on the surface as determined by Western blotting and immunofluorescence. Results: On preincubation with anti-SCPA serum, the isogenic M1(-) strain exhibited 54 per cent decreased invasion as compared to the bacteria incubated with control serum. Also, purified recombinant SCPA proteins blocked internalization of M1(-) streptococci into HEp-2 cells. The M1(-) strain invaded at the same efficiency in the presence or absence of fibronectin. Interpretation & conclusion: These results suggested that SCPA acted as a potential invasin of group A streptococcus and promoted invasion independent of fibronectin.

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Distributed Collaborative Computing services have taken over centralized computing platforms allowing the development of distributed collaborative user applications. These applications enable people and computers to work together more productively. Multi-Agent System (MAS) has emerged as a distributed collaborative environment which allows a number of agents to cooperate and interact with each other in a complex environment. We want to place our agents in problems whose solutions require the collation and fusion of information, knowledge or data from distributed and autonomous information sources. In this paper we present the design and implementation of an agent based conference planner application that uses collaborative effort of agents which function continuously and autonomously in a particular environment. The application also enables the collaborative use of services deployed geographically wide in different technologies i.e. Software Agents, Grid computing and Web service. The premise of the application is that it allows autonomous agents interacting with web and grid services to plan a conference as a proxy to their owners (humans). © 2005 IEEE.

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Information exchange (IE) is a critical component of the complex collaborative medication process in residential aged care facilities (RACFs). Designing information and communication technology (ICT) to support complex processes requires a profound understanding of the IE that underpins their execution. There is little existing research that investigates the complexity of IE in RACFs and its impact on ICT design. The aim of this study was thus to undertake an in-depth exploration of the IE process involved in medication management to identify its implications for the design of ICT. The study was undertaken at a large metropolitan facility in NSW, Australia. A total of three focus groups, eleven interviews and two observation sessions were conducted between July to August 2010. Process modelling was undertaken by translating the qualitative data via in-depth iterative inductive analysis. The findings highlight the complexity and collaborative nature of IE in RACF medication management. These models emphasize the need to: a) deal with temporal complexity; b) rely on an interdependent set of coordinative artefacts; and c) use synchronous communication channels for coordination. Taken together these are crucial aspects of the IE process in RACF medication management that need to be catered for when designing ICT in this critical area. This study provides important new evidence of the advantages of viewing process as a part of a system rather than as segregated tasks as a means of identifying the latent requirements for ICT design and that is able to support complex collaborative processes like medication management in RACFs. © 2012 IEEE.

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The product of the bglG gene of Escherichia coli was among the first bacterial antiterminators to be identified and characterized. Since the elucidation ten years ago of its role in the regulation of the bgl operon of E. coli,a large number of homologies have been discovered in both Gram-positive and Gram-negative bacteria. Often the homologues of BglG in other organisms are also involved in regulating β-glucoside utilization. Surprisingly, in many cases, they mediate antitermination to regulate a variety of other catabolic functions. Because of the high degree of conservation of the cis-acting regulatory elements, antiterminators from one organism can function in another. Generally the antiterminator protein itself is negatively regulated by phosphorylation by a component of the phosphotransferase system. This family of proteins thus represents a highly evolved regulatory system that is conserved across evolutionarily distant genuses.

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Let X be a normal projective threefold over a field of characteristic zero and vertical bar L vertical bar be a base-point free, ample linear system on X. Under suitable hypotheses on (X, vertical bar L vertical bar), we prove that for a very general member Y is an element of vertical bar L vertical bar, the restriction map on divisor class groups Cl(X) -> Cl(Y) is an isomorphism. In particular, we are able to recover the classical Noether-Lefschetz theorem, that a very general hypersurface X subset of P-C(3) of degree >= 4 has Pic(X) congruent to Z.

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The parasitic wasps are one of the largest insect groups and their life histories are remarkably variable. Common to all parasitic wasps is that they kill their hosts, which are usually beetles, butterflies and sometimes spiders. Hosts are often at a larval or pupal stage and live in concealed conditions, such as in plant tissue. Parasitic wasps have two main ways of finding their host. 1) They can detect chemical compounds emitted by damaged plant material or released by larvae living in plant tissue, and 2) detect the larvae by sound vibrations. Even though pupae are immobile and silent, and therefore do not cause vibration, parasitoids have, however, adapted to find passive developmental stages by producing vibration themselves by knocking the substrate with their antennae, and then detecting the echoes with their legs. This echolocation allows a parasitoid to locate its potential hosts that are deeply buried in wood. This study focuses on the relationships of the subfamily Cryptinae (Hymenoptera: Ichneumonidae) and related taxa, and the evolution of host location mechanism. There are no earlier studies of the phylogeny of the Cryptinae, and the position of related taxa are unclear. According to the earlier classification, which is entirely intuitional, the Cryptinae is divided into three tribes: Cryptini, Hemigasterini and Phygadeuontini. Further, these tribes are subdiveded into numerous subtribes. This work, based on molecular characters, shows that the cryptine tribes Cryptini, Phygadeuon¬tini and Hemigasterini come out largely as monophyletic groups, thus agreeing with the earlier classification. The earlier subtribal classification had no support. In addition, it is shown that modified antennal structures are associated with host usage of wood-boring coleopteran hosts. The cryptines have a clear modification series on their antennal tips from a simply tip to a hammer-like structure. The species with strongly modified antennae belong mostly to the tribe Cryptini and they utilise wood-boring beetles as hosts. Also, field observations on insect behaviour support this result.

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Despite tertiary institutions acknowledging that reflective practice is an essential component of undergraduate dance teacher training, there is often a disparity between the tertiary students’ reflective skills and the more sophisticated reflective ability needed to navigate the 21st century workforce (Silva 2008). This paper charts the evolution of a dance teaching reflective pedagogy within a suite of three units across a three-year undergraduate dance teacher-training course for school, community and studio dance teachers. This reflective pedagogy based on exploration, collaboration, critical questioning and connections with community forms the basis of a model of tertiary dance teacher- training; the Performance in Context Model (PCM). Over the past four years, through four cycles of action research, the PCM pedagogy, context and engagement with community has developed into a successful model integrating practical dance teaching skills, artistry and community engagement. The PCM represents a holistic collaborative approach to dance teacher education: the marrying of ‘teacher-as-artist’, ‘teacher-as-performer’ and ‘teacher-as-researcher’. More specifically, it emphasises the need for mature, reflective, receptive and flexible approaches in response to dance teaching and learning. These are enacted in a variety of contexts, with tertiary dance teaching students identifying as teaching artists, as well as researchers of their own practice.

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Background: Fatty acids are indispensable constituents of mycolic acids that impart toughness & permeability barrier to the cell envelope of M. tuberculosis. Biotin is an essential co-factor for acetyl-CoA carboxylase (ACC) the enzyme involved in the synthesis of malonyl-CoA, a committed precursor, needed for fatty acid synthesis. Biotin carboxyl carrier protein (BCCP) provides the co-factor for catalytic activity of ACC. Methodology/Principal Findings: BPL/BirA (Biotin Protein Ligase), and its substrate, biotin carboxyl carrier protein (BCCP) of Mycobacterium tuberculosis (Mt) were cloned and expressed in E. coli BL21. In contrast to EcBirA and PhBPL, the similar to 29.5 kDa MtBPL exists as a monomer in native, biotin and bio-5'AMP liganded forms. This was confirmed by molecular weigt profiling by gel filtration on Superdex S-200 and Dynamic Light Scattering (DLS). Computational docking of biotin and bio-5'AMP to MtBPL show that adenylation alters the contact residues for biotin. MtBPL forms 11 H-bonds with biotin, relative to 35 with bio-5'AMP. Docking simulations also suggest that bio-5'AMP hydrogen bonds to the conserved `GRGRRG' sequence but not biotin. The enzyme catalyzed transfer of biotin to BCCP was confirmed by incorporation of radioactive biotin and by Avidin blot. The K-m for BCCP was similar to 5.2 mu M and similar to 420 nM for biotin. MtBPL has low affinity (K-b = 1.06 x 10(-6) M) for biotin relative to EcBirA but their K-m are almost comparable suggesting that while the major function of MtBPL is biotinylation of BCCP, tight binding of biotin/bio-5'AMP by EcBirA is channeled for its repressor activity. Conclusions/Significance: These studies thus open up avenues for understanding the unique features of MtBPL and the role it plays in biotin utilization in M. tuberculosis.

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Aromatic aldehydes and aryl isocyanates do not react at room temperature. However, we have shown for the first time that in the presence of catalytic amounts of group(IV) n-butoxide, they undergo metathesis at room temperature to produce imines with the extrusion of carbon dioxide. The mechanism of action has been investigated by a study of stoichiometric reactions. The insertion of aryl isocyanates into the metal n-butoxide occurs very rapidly. Reaction of the insertion product with the aldehyde is responsible for the metathesis. Among the n-butoxides of group(IV) metals, Ti((OBu)-Bu-n)(4) (8aTi) was found to be more efficient than Zr((OBu)-Bu-n)(4) (8aZr) and Hf((OBu)-Bu-n)(4) (8aHf) in carrying out metathesis. The surprisingly large difference in the metathetic activity of these alkoxides has been probed computationally using model complexes Ti(OMe)(4) (8bTi), Zr(OMe)(4) (8bZr) and Hf(OMe)(4) (8bHf) at the B3LYP/LANL2DZ level of theory. These studies indicate that the insertion product formed by Zr and Hf are extremely stable compared to that formed by Ti. This makes subsequent reaction of Zr and Hf complexes unfavorable.

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The crystal structures of three conformationally locked esters, namely the centrosymmetric tetrabenzoate of all-axial per-hydronaphthalene- 2,3,4a, 6,7,8a-hexaol, viz. trans-4a, 8a-dihydroxyperhydronaphthalene-2,3,6,7-tetrayl tetrabenzoate, C38H34O10, and the diacetate and dibenzoate of all-axial perhydronaphthalene-2,3,4a, 8a-tetraol, viz. (2R*,3R*,4aS*,8aS*)-4a, 8a-dihydroxyperhydronaphthalene-2,3-diyl diacetate, C-14-H22O6, and (2R*, 3R*, 4aS*, 8aS*)-4a, 8a-dihydroxyperhydronaphthalene- 2,3-diyl dibenzoate, C24H26O6, have been analyzed in order to examine the preference of their supramolecular assemblies towards competing inter-and intramolecular O-H center dot center dot center dot O hydrogen bonds. It was anticipated that the supramolecular assembly of the esters under study would adopt two principal hydrogen-bonding modes, namely one that employs intermolecular O-H center dot center dot center dot O hydrogen bonds (mode 1) and another that sacrifices those for intramolecular O-H center dot center dot center dot O hydrogen bonds and settles for a crystal packing dictated by weak intermolecular interactions alone (mode 2). Thus, while the molecular assembly of the two crystalline diacyl derivatives conformed to a combination of hydrogen-bonding modes 1 and 2, the crystal packing in the tetrabenzoate preferred to follow mode 2 exclusively.

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Let D be a bounded domain in C 2 with a non-compact group of holomorphic automorphisms. Model domains for D are obtained under the hypotheses that at least one orbit accumulates at a boundary point near which the boundary is smooth, real analytic and of finite type.

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The international trend towards an increasingly standards-based approach to higher education and the resultant focus on the assurance of learning in tertiary programs have generated a strong emphasis on the assessment of outcomes across the higher education sector. In legal education, curriculum reform is highly prevalent internationally as a result of various reviews of legal education. As legal education focuses more on the attainment of a broader set of outcomes encompassing soft skills, capabilities and attributes, more authentic assessment will need to be developed appropriate to this new environment, meaning that modes of assessment with strong application in real-life settings should be preferred.

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We carry out a systematic construction of the coarse-grained dynamical equation of motion for the orientational order parameter for a two-dimensional active nematic, that is a nonequilibrium steady state with uniaxial, apolar orientational order. Using the dynamical renormalization group, we show that the leading nonlinearities in this equation are marginally irrelevant. We discover a special limit of parameters in which the equation of motion for the angle field bears a close relation to the 2d stochastic Burgers equation. We find nevertheless that, unlike for the Burgers problem, the nonlinearity is marginally irrelevant even in this special limit, as a result of a hidden fluctuation-dissipation relation. 2d active nematics therefore have quasi-long-range order, just like their equilibrium counterparts.

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Streptococcus pyogenes [group A streptococcus (GAS)], a human pathogen, and Streptococcus dysgalactiae subsp. equisimilis [human group G and C streptococcus (GGS/GCS)] are evolutionarily related, share the same tissue niche in humans, exchange genetic material, share up to half of their virulence-associated genes and cause a similar spectrum of diseases. Yet, GGS/GCS is often considered as a commensal bacterium and its role in streptococcal disease burden is under-recognized. While reports of the recovery of GGS/GCS from normally sterile sites are increasing, studies describing GGS/GCS throat colonization rates relative to GAS in the same population are very few. This study was carried out in India where the burden of streptococcal diseases, including rheumatic fever and rheumatic heart disease, is high. As part of a surveillance study, throat swabs were taken from 1504 children attending 7 municipal schools in Mumbai, India, during 2006-2008. GAS and GGS/GCS were identified on the basis of beta-haemolytic activity, carbohydrate group and PYR test, and were subsequently typed. The GGS/GCS carriage rate (1166/1504, 11%) was eightfold higher than the GAS carriage (22/1504, 1.5%) rate in this population. The 166 GGS/GCS isolates collected represented 21 different emm types (molecular types), and the 22 GAS isolates represented 15 different emm types. Although the rate of pharyngitis associated with GGS/GCS is marginally lower than with GAS, high rates of throat colonization by GGS/GCS underscore its importance in the pathogenesis of pharyngitis.