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  • 1
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Estuarine sediments commonly form major sinks for contaminants released during industrial activity. Many industrial processes lead to the release of metals initially in solution, which can then be adsorbed on to, for example, Fe hydroxides or clay minerals. However, in the mining industry, there are two major contaminant waste streams: (1) metals discharged in solution via mine drainage; and (2) particulate grains of the ore-forming or related minerals released after ore processing. The release of particulate waste can have a major long-term impact on environmental geochemistry. In this study, we have mapped the distribution of arsenic, copper, tin and zinc within the surficial sediments of the Fal Estuary, Cornwall, UK, an area that drains a historically important polymetallic mining district. There are clear spatial variations in the contaminants, with the highest levels (〉 2800 p.p.m. As, 〉 5000 p.p.m. Cu, 〉 3000 p.p.m. Sn and 〉 6000 p.p.m. Zn) within Restronguet Creek on the western side of the estuary. Mineralogical studies show that small (〈 20 µm) grains of detrital arsenopyrite, chalcopyrite, cassiterite and sphalerite are very abundant within the surface sediments. Most of the sulphide grains are fractured, but mineralogically unaltered, although some grains show alteration rims caused by oxidation of the sulphides. The geochemistry and mineralogy are indicative of sediment supply from the discharge of particulate waste into the estuary during historical mining activity. Subsequently, this particulate waste has been largely physically and biologically reworked within the surface sediments. Although considerable effort has been made to minimize contaminants released via mine drainage into the estuary, the potential flux of contaminants present within the intertidal and subtidal sediments has not been addressed. Benthic invertebrates living within the area have adapted to be metal tolerant, and it is likely that the dominant source of bioavailable metals is a result of alteration of the particulate mine waste present within the intertidal and subtidal sediments.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK and Malden, USA : Blackwell Science Ltd
    International journal of consumer studies 27 (2003), S. 0 
    ISSN: 1470-6431
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    International journal of consumer studies 26 (2002), S. 0 
    ISSN: 1470-6431
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    International journal of consumer studies 25 (2001), S. 0 
    ISSN: 1470-6431
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
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  • 5
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The genome sequence of Helicobacter pylori suggests that this bacterium possesses several Fe acquisition systems, including both Fe2+- and Fe3+-citrate transporters. The role of these transporters was investigated by generating insertion mutants in feoB, tonB, fecA1 and fecDE. Fe transport in the feoB mutant was ≈ 10-fold lower than in the wild type (with 0.5 μM Fe), irrespective of whether Fe was supplied in the Fe2+ or Fe3+ form. In contrast, transport rates were unaffected by the other mutations. Complementation of the feoB mutation fully restored both Fe2+ and Fe3+ transport. The growth inhibition exhibited by the feoB mutant in Fe-deficient media was relieved by human holo-transferrin, holo-lactoferrin and Fe3+-dicitrate, but not by FeSO4. The feoB mutant had less cellular Fe and was more sensitive to growth inhibition by transition metals in comparison with the wild type. Biphasic kinetics of Fe2+ transport in the wild type suggested the presence of high- and low-affinity uptake systems. The high-affinity system (apparent Ks = 0.54 μM) is absent in the feoB mutant. Transport via FeoB is highly specific for Fe2+ and was inhibited by FCCP, DCCD and vanadate, indicating an active process energized by ATP. Ferrozine inhibition of Fe2+ and Fe3+ uptake implied the concerted involvement of both an Fe3+ reductase and FeoB in the uptake of Fe supplied as Fe3+. Taken together, the results are consistent with FeoB-mediated Fe2+ uptake being a major pathway for H. pylori Fe acquisition. feoB mutants were unable to colonize the gastric mucosa of mice, indicating that FeoB makes an important contribution to Fe acquisition by H. pylori in the low-pH, low-O2 environment of the stomach.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 37 (2000), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Reductions in growth rate caused by fusidic acid-resistant EF-G mutants in Salmonella typhimurium correlate strongly with increased mean cell size. This is unusual because growth rate and cell size normally correlate positively. The global transcription regulator molecule ppGpp has a role in co-ordinating growth rate and division, and its basal level normally correlates inversely with cell size at division. We show that fusidic acid-resistant EF-G mutants have perturbed ppGpp basal levels during steady-state growth and perturbed induced levels during starvation. One mutation, fusA1, associated with the slowest growth rate and largest cell size, causes a reduction in the basal level of ppGpp to one-third of that found in the wild-type strain. Other fusA mutants with intermediate or wild-type growth rates and cell sizes have either normal or increased basal levels of ppGpp. There is an inverse relationship between the basal level of ppGpp in vivo and the degree to which translation dependent on mutant EF-G is inhibited by ppGpp in vitro. This enhanced interaction between mutant EF-G and ppGpp correlates with an increased KM for GTP. Our results suggest that mutant EF-G modulates the production of ppGpp by the RelA (PSI) pathway. In conclusion, fusidic acid-resistant EF-G mutations alter the level of ppGpp and break the normal relationship between growth rate and cell size at division. It would not be surprising if other phenotypes associated with these mutants, such as loss of virulence, were also related to perturbations in ppGpp levels effected through altered transcription patterns.
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  • 7
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Serratia sp. ATCC 39006 (39006) uses a complex hierarchical regulatory network allowing multiple inputs to be assessed before genes involved in secondary metabolite biosynthesis are expressed. This taxonomically ill-defined Serratia sp. produces a carbapenem antibiotic (Car; a β-lactam) and a red pigmented antibiotic, prodigiosin (Pig; a tripyrrole), which are controlled by the smaIR quorum sensing (QS) locus. SmaR is a repressor of Pig and Car when levels of N-acyl- l-homoserine lactones, produced by SmaI, are low. In this study, we demonstrate direct DNA binding of purified SmaR to the promoter of the Car biosynthetic genes and abolition of this binding by the QS ligand. We have also identified multiple new secondary metabolite regulators. QS controls production of secondary metabolites, at least in part, by modulating transcription of three genes encoding regulatory proteins, including a putative response regulator of the GacAS two-component signalling system family, a novel putative adenylate cyclase and Rap (regulator of antibiotic and pigment). Mutations in another gene encoding a novel predicted global regulator, pigP, are highly pleiotropic; PigP has a significant ‘master’ regulatory role in 39006 where it controls the transcription of six other regulators. The PigP protein and its homologues define a new family of regulators and are predicted to bind DNA via a helix-turn-helix domain. There are regulatory overlaps between the QS and PigP regulons that enable the information from different physiological cues to be funnelled into the control of secondary metabolite production.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The analysis of a candidate biosynthetic gene cluster (97 kbp) for the polyether ionophore monensin from Streptomyces cinnamonensis has revealed a modular polyketide synthase composed of eight separate multienzyme subunits housing a total of 12 extension modules, and flanked by numerous other genes for which a plausible function in monensin biosynthesis can be ascribed. Deletion of essentially all these clustered genes specifically abolished monensin production, while overexpression in S. cinnamonensis of the putative pathway-specific regulatory gene monR led to a fivefold increase in monensin production. Experimental support is presented for a recently-proposed mechanism, for oxidative cyclization of a linear polyketide intermediate, involving four enzymes, the products of monBI, monBII, monCI and monCII. In frame deletion of either of the individual genes monCII (encoding a putative cyclase) or monBII (encoding a putative novel isomerase) specifically abolished monensin production. Also, heterologous expression of monCI, encoding a flavin-linked epoxidase, in S. coelicolor was shown to significantly increase the ability of S. coelicolor to epoxidize linalool, a model substrate for the presumed linear polyketide intermediate in monensin biosynthesis.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    International journal of consumer studies 27 (2003), S. 0 
    ISSN: 1470-6431
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    International journal of consumer studies 29 (2005), S. 0 
    ISSN: 1470-6431
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: Research evidence suggests that UK consumers are facing significant problems with goods and services and are in need of information and advice to avoid or redress such situations. Consumers are not always aware of their rights nor where they can access consumer advice services. In 2000, the Department of Trade and Industry launched the Consumer Support Network (CSN) programme in Great Britain to improve consumer access to expert, accurate and timely advice. One challenge faced by these Networks and many other agencies is to assess the needs of consumers for consumer information and advice services. A needs assessment is required as a key element in the effective planning and development of services in each Network at a local level. The focus of the needs assessment at the local level is to encourage Networks to consider suitable solutions to meet the needs of people in their communities. This paper provides a review of the development of Consumer Support Networks in Great Britain and discusses the importance of needs assessment to service providers such as CSNs and other agencies. It reveals the complexity associated with conducting effective needs assessments including the various aspects of needs, consumer segmentation and characteristics of consumer information and advice. Further research is being carried out at Queen Margaret University College, UK, with a view to the development of a scientific model for the assessment of need for consumer information and advice services.
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