1,554 research outputs found
Orthomercurated and cycloaurated derivatives of the iminophosphorane Ph3P NPh
Ortho-lithiation of Ph3P NPh followed by reaction with HgCl2 gave good yields of [Hg{C6H4(PPh2 NPh)-2}Cl], 3, which was characterised spectroscopically and by an X-ray crystal structure determination. This is an isomer of the product of direct mercuration of Ph3P NPh which occurs on the N-bonded phenyl ring [J. Vicente, J.A. Abad, R. Clemente, J. Lopez-Serrano, M.C. Ramirez de Arellano, P.G. Jones, D. Bautista, Organometallics, 22 (2003) 4248]. Transmetallation of 3 with [AuCl4]− gave the corresponding cycloaurated complex [Au{κ2-C,N-C6H4(PPh2 NPh)-2}Cl2], with a five-membered metallocyclic ring incorporating four different elements
Coffee-Stability of Agglomerated Whole Milk Powder and other Dairy Creamer Emulsions
End of Project ReportThe objectives of this project were: (a) to investigate the circumstances that cause
milk powders and creamers to fail when added to coffee based beverages; (b) to evaluate
the role of processing variables in relation to their thermostabilising effects on milk during
drying of coffee whiteners; and (c) to determine the role of emulsion formation on the
stability of imitation creamers.Department of Agriculture, Food and the Marin
Conservation of structure and mechanism in primary and secondary transporters exemplified by SiaP, a sialic acid binding virulence factor from Haemophilus influenzae
Extracytoplasmic solute receptors (ESRs) are important components of solute uptake systems in bacteria, having been studied extensively as parts of ATP binding cassette transporters. Herein we report the first crystal structure of an ESR protein from a functionally characterized electrochemical ion gradient-dependent secondary transporter. This protein, SiaP, forms part of a tripartite ATP-independent periplasmic transporter specific for sialic acid in Haemophilus influenzae. Surprisingly, the structure reveals an overall topology similar to ATP binding cassette ESR proteins, which is not apparent from the sequence, demonstrating that primary and secondary transporters can share a common structural component. The structure of SiaP in the presence of the sialic acid analogue 2,3-didehydro-2-deoxyN-acetylneuraminic acid reveals the ligand bound in a deep cavity with its carboxylate group forming a salt bridge with a highly conserved Arg residue. Sialic acid binding, which obeys simple bimolecular association kinetics as determined by stopped-flow fluorescence spectroscopy, is accompanied by domain closure about a hinge region and the kinking of an alpha-helix hinge component. The structure provides insight into the evolution, mechanism, and substrate specificity of ESR-dependent secondary transporters that are widespread in prokaryotes
Tripartite ATP-Independent Periplasmic (TRAP) Transporters and Tripartite Tricarboxylate Transporters (TTT): From Uptake to Pathogenicity
The ability to efficiently scavenge nutrients in the host is essential for the viability of any pathogen. All catabolic pathways must begin with the transport of substrate from the environment through the cytoplasmic membrane, a role executed by membrane transporters. Although several classes of cytoplasmic membrane transporters are described, high-affinity uptake of substrates occurs through Solute Binding-Protein (SBP) dependent systems. Three families of SBP dependant transporters are known; the primary ATP-binding cassette (ABC) transporters, and the secondary Tripartite ATP-independent periplasmic (TRAP) transporters and Tripartite Tricarboxylate Transporters (TTT). Far less well understood than the ABC family, the TRAP transporters are found to be abundant among bacteria from marine environments, and the TTT transporters are the most abundant family of proteins in many species of β-proteobacteria. In this review, recent knowledge about these families is covered, with emphasis on their physiological and structural mechanisms, relating to several examples of relevant uptake systems in pathogenicity and colonization, using the SiaPQM sialic acid uptake system from Haemophilus influenzae and the TctCBA citrate uptake system of Salmonella typhimurium as the prototypes for the TRAP and TTT transporters, respectively. High-throughput analysis of SBPs has recently expanded considerably the range of putative substrates known for TRAP transporters, while the repertoire for the TTT family has yet to be fully explored but both types of systems most commonly transport carboxylates. Specialized spectroscopic techniques and site-directed mutagenesis have enriched our knowledge of the way TRAP binding proteins capture their substrate, while structural comparisons show conserved regions for substrate coordination in both families. Genomic and protein sequence analyses show TTT SBP genes are strikingly overrepresented in some bacteria, especially in the β-proteobacteria and some α-proteobacteria. The reasons for this are not clear but might be related to a role for these proteins in signaling rather than transport
The value of 'community' in supporting transitions outside university
Statistics from the Destinations of Leavers in Higher Education (DLHE) survey has shown that graduate level employment or study 6 months after graduation is relatively low for psychology graduates compared to graduates from other disciplines. Due to highly competitive conditions for postgraduate places on professional psychology training courses, new graduates often spend time developing their portfolio of relevant skills and experience in order to compete for postgraduate places one or more years after graduating. In addition, QAA (2010) noted that only 15-20% of psychology graduates develop careers as professional psychologists. Many initiatives have been introduced across the UK (see Reddy, Lantz, & Hulme, 2013) to support students' transitions out of university and into employment or further study, however these initiatives vary in the extent to which they are embedded and capture student engagement. At the University of Strathclyde, we are taking a multi-pronged approach to enhancing students’ employability that is underpinned by an ethos of ‘community’. First, the creation of the Strathclyde Psychology Alumni Network (SPAN), developed in collaboration with students, provides a platform through which current students, alumni, and staff, interact as members of the Strathclyde Psychology Community, virtually via LinkedIn and face-to-face at networking events. Second, a new work placement class in the final year will provide students the opportunity to enhance their experience and apply their psychological knowledge and skills in a work-based context. Third, a novel curriculum review process involving staff, alumni, and employers (representing private, public, and third sectors) has sought to identify the opportunities and challenges that graduates face, and the characteristics of the ‘Ideal Strathclyde Psychology Graduate’. A core competency framework will be output from this process and will drive the curriculum enhancement process so that students have the opportunity to develop the characteristics of the ‘Ideal Strathclyde Psychology Graduate’
Report of the SNOMS Project 2006 to 2012, SNOMS SWIRE NOCS Ocean Monitoring System. Part 1: Narrative description
The ocean plays a major role in controlling the concentration of carbon dioxide (CO2) in the atmosphere. Increasing concentrations of CO2 in the atmosphere are a threat to the stability of the earth’s climate. A better understanding of the controlling role of the ocean will improve predictions of likely future changes in climate and the impact of the uptake of CO2 itself on marine eco-systems caused by the associated acidification of the ocean waters. The SNOMS Project (SWIRE NOCS Ocean Monitoring System) is a ground breaking joint research project supported by the Swire Group Trust, the Swire Educational Trust, the China Navigation Company (CNCo) and the Natural Environment Research Council. It collects high quality data on concentrations of CO2 in the surface layer of the ocean. It contributes to the international effort to better quantify (and understand the driving processes controlling) the exchanges of CO2 between the ocean and the atmosphere. In 2006 and 2007 a system that could be used on a commercial ship to provide data over periods of several months with only limited maintenance by the ships crew was designed and assembled by NOCS. The system was fitted to the CNCo ship the MV Pacific Celebes in May 2007. The onboard system was supported by web pages that monitored the progress of the ship and the functioning of the data collection system. To support the flow of data from the ship to the archiving of the data at the Carbon Dioxide Information Analysis Center (CDIAC in the USA) data processing procedures were developed for the quality control and systematic handling of the data. Data from samples of seawater collected by the ships crew and analysed in NOC (730 samples) have been used to confirm the consistency of the data from the automated measurement system on the ship. To examine the data collected between 2007 and 2012 the movements of the ship are divided into 16 voyages. Initially The Celebes traded on a route circum-navigating the globe via the Panama and Suez Canals. In 2009 the route shifted to one between Australia and New Zealand to USA and Canada. Analysis of the data is an on going process. It has demonstrated that the system produces reliable data. Data are capable of improving existing estimates of seasonal variability. The work has improved knowledge of gas exchange processes. Data from the crew-collected-samples are helping improve our ability to estimate alkalinity in different areas. This helps with the study of ocean acidification. Data from the 9 round trips in the Pacific are currently being examined along with data made available by the NOAA-PMEL laboratory forming time series from 2004 to 2012. The data from the Pacific route are of considerable interest. One reason is that the data monitors variations in the fluxes of CO2 associated with the current that flows westwards along the equator. This is one of the major natural sources of CO2 from the ocean into the atmosphere
Combination therapy with tranilast and angiotensin-converting enzyme inhibition provides additional renoprotection in the remnant kidney model
Despite current therapy with agents that block the renin–angiotensin system, renal dysfunction continues to progress in a significant proportion of patients with kidney disease. Several pre-clinical studies have reported beneficial effects of tranilast, an inhibitor of transforming growth factor (TGF)-β's actions in a range of diseases that are characterized by fibrosis. However, whether such therapy provides additional benefits in renal disease, when added to angiotensin-converting enzyme (ACE) inhibition, has not been explored. We randomized subtotally (5/6) nephrectomized rats to receive vehicle, the ACE inhibitor, perindopril (6 mg/l), tranilast (400 mg/kg/day), or their combination for 12 weeks. When compared with sham-nephrectomized animals, subtotally nephrectomized animals had reduced creatinine clearance, proteinuria, glomerulosclerosis, interstitial fibrosis, tubular atrophy, and evidence of TGF-β activity, as indicated by the abundant nuclear staining of phosphorylated Smad2. These manifestations of injury and TGF-β activation were all attenuated by treatment with either tranilast or perindopril, with the latter also attenuating the animals’ hypertension. When compared with single-agent treatment, the combination of tranilast and perindopril provided additional, incremental improvements in creatinine clearance, proteinuria, and glomerulosclerosis, and a reduction in nuclear phsopho-Smad2 beyond single-agent treatment. These findings indicate that the combination of tranilast and perindopril was superior to single-agent treatment on kidney structure and function in the remnant kidney model, and suggests the potential for such dual therapy in kidney disease that continues to progress despite blockade of the renin–angiotensin system
Numerical framework for seismic collapse assessment of rigid wall-flexible diaphragm structures
This study focuses on the development of a two dimensional (2D) simplified numerical framework of rigid wall-flexible diaphragm (RWFD) structures that can be used to validate seismic design approaches. This type of low-rise industrial buildings, which is widely used in North America, incorporates rigid in-plane concrete or masonry walls and flexible in-plane wood, steel or “hybrid” roof diaphragms. The numerical modeling is detailed enough to capture the nonlinear seismic response of RWFD buildings, but simplified enough to efficiently conduct a large number of nonlinear time-history dynamic analyses. The 2D numerical modeling framework is based on a three step sub-structuring approach including: (1) a hysteretic response database for diaphragm connectors, (2) a 2D inelastic roof diaphragm model incorporating hysteretic connector response and (3) a simplified 2D building model incorporating hysteretic diaphragm model response. The diaphragm connector database (step 1) was developed for both wood and steel deck connectors using cyclic test data available in the literature. Two well-known hysteretic models (Wayne-Stewart and CUREE-SAWS) were used for estimating/fitting hysteretic parameters of each connector type. The analytical model of the inelastic roof diaphragm (step 2) was generated to account for the elastic shear deformation of deck panels, elastic flexural deformations of chord members as well as inelastic deformations of deck-to-frame connectors (from the connector database-step 1). This model includes monotonic and cyclic analysis capabilities. The last step of the proposed analytical framework is a simplified two dimensional model of a RWFD building developed in RUAUMOKO2D to account for the inelastic response of roof diaphragms (based on the analytical roof diaphragm model-step 2) and the out-of-plane walls as well as second order (P-Δ) effects. Both the proposed analytical model of the roof diaphragm and the proposed simplified building model were validated with experimental and analytical studies available in the literature. Furthermore, a sensitivity study was conducted to examine the effect of: (i) analysis time step, (ii) different base fixity of the out-of-plane walls, (iii) P-Δ effects, (iv) inherent viscous damping and (v) direction of shaking on the collapse assessment of RWFD structures
Massive over-representation of solute-binding proteins (SBPs) from the tripartite tricarboxylate transporter (TTT) family in the genome of the α-proteobacterium Rhodoplanes sp. Z2-YC6860.
Lineage-specific expansion (LSE) of protein families is a widespread phenomenon in many eukaryotic genomes, but is generally more limited in bacterial genomes. Here, we report the presence of 434 genes encoding solute-binding proteins (SBPs) from the tripartite tricarboxylate transporter (TTT) family, within the 8.2 Mb genome of the α-proteobacterium Rhodoplanes sp. Z2-YC6860, a gene family over-representation of unprecedented abundance in prokaryotes. Representing over 6 % of the total number of coding sequences, the SBP genes are distributed across the whole genome but are found rarely in low-GC islands, where the gene density for this family is much lower. This observation, and the much higher sequence identity between the 434 Rhodoplanes TTT SBPs compared with the average identity between homologues from different species, is indicative of a key role for LSE in the expansion. The TTT SBP genes were found in the vicinity of genes encoding membrane components of transport systems from different families, as well as regulatory proteins such as histidine-kinases and transcription factors, indicating a broad range of functions around the sensing, response and transport of organic compounds. A smaller expansion of TTT SBPs is known in some species of the β-proteobacteria Bordetella and we observed similar expansions in other β-proteobacterial lineages, including members of the genus Comamonas and the industrial biotechnology organism Cupriavidus necator, indicating that strong environmental selection can drive SBP duplication and specialisation from multiple evolutionary starting points
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Bacterial periplasmic nitrate and trimethylamine-N-oxide respiration coupled to menaquinol-cytochrome c reductase (Qcr): implications for electrogenic reduction of alternative electron acceptors.
The periplasmic reduction of the electron acceptors nitrate (Em +420 mV) and trimethylamine-N-oxide (TMAO; Em +130 mV) by Nap and Tor reductases is widespread in Gram-negative bacteria and is usually considered to be driven by non-energy conserving quinol dehydrogenases. The Epsilonproteobacterium Campylobacter jejuni can grow by nitrate and TMAO respiration and it has previously been assumed that these alternative pathways of electron transport are independent of the proton-motive menaquinol-cytochrome c reductase complex (QcrABC) that functions in oxygen-linked respiration. Here, we show that a qcrABC deletion mutant is completely deficient in oxygen-limited growth on both nitrate and TMAO and is unable to reduce these oxidants with physiological electron donors. As expected, the mutant grows normally on fumarate under oxygen-limited conditions. Thus, the periplasmic Nap and Tor reductases receive their electrons via QcrABC in C. jejuni, explaining the general absence of NapC and TorC quinol dehydrogenases in Epsilonproteobacteria. Moreover, the specific use of menaquinol (Em -75 mV) coupled with a Qcr complex to drive reduction of nitrate or TMAO against the proton-motive force allows the process to be electrogenic with a H+/2e- ratio of 2. The results have general implications for the role of Qcr complexes in bacterial oxygen-independent respiration and growth
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