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  • 11
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A new facility for simultaneous extended X-ray absorption of fine structure (EXAFS), X-ray diffraction and photoluminescence measurements under high pressures has been developed for use on station 9.3 at the Daresbury Laboratory Synchrotron Radiation Source. This high-pressure facility can be used at any suitable beamline at a synchrotron source. Full remote operation of the rig allows simultaneous collection of optical and structural data while varying the pressure. The set-up is very flexible and can be tailored for a particular experiment, such as time- or temperature-dependent measurements. A new approach to the collection of high-pressure EXAFS data is also presented. The approach significantly shortens the experimental times and allows a dramatic increase in the quality of EXAFS data collected. It also opens up the possibility for EXAFS data collection at any pressure which can be generated using a diamond cell. The high quality of data collected is demonstrated with a GaN case study. Particular attention will be paid to the use of energy-dispersive EXAFS and quick-scanning EXAFS techniques under pressure.
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  • 12
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The mechanisms regulating stomatal response following exposure to low (5°C) soil temperature were investigated in aspen (Populus tremuloides Michx.) seedlings. Low soil temperature reduced stomatal conductance within 4 h, but did not alter shoot xylem pressure potential within 24 h. The xylem sap composition was altered and its pH increased from 6.5 to 7.1 within the initial 4 h of the low temperature treatment. However, the increase in abscisic acid (ABA) concentration in xylem sap was observed later, after 8 h of treatment. These changes were accompanied by a reduction in the electrical conductivity and an increase in the osmotic potential of the xylem sap. The timing of physiological responses to low soil temperature suggests that the rapid pH change of the xylem sap and accompanying changes in ion concentration were the initial factors which triggered stomatal closure in low temperature-treated seedlings, and that the role of the more slowly accumulating ABA was likely to reinforce the stomatal closure. When leaf discs were exposed to xylem sap extracted from low soil temperature-treated plants, stomatal aperture was negatively correlated with ABA and positively correlated with K+ concentrations of the xylem sap. The stomatal opening in the leaf discs linearly increased in response to exogenous KCl concentrations when K+ concentrations were in the similar range to those detected in the xylem sap. The lowest concentration of exogenous ABA to induce stomatal closure was several-fold higher compared with the concentration present in the xylem sap.
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  • 13
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: SpoIVB is the critical determinant for intercompartmental signalling of pro-σK processing during sporulation in Bacillus subtilis. We show here that the SpoIVB serine peptidase can cleave the SpoIVFA protein, which is one component of the pro-σK processing complex. SpoIVFA has been shown elsewhere (Rudner, D.Z., and Losick, R., 2002, Genes Dev 16: 1007–1018) to tether BofA and SpoIVFB in a membrane-embedded heteroligomeric complex in which BofA directly inhibits the activity of SpoIVFB. Cleavage of SpoIVFA would provide the necessary signal to dissolve this complex and release BofA-mediated inhibition on the zinc metalloprotease, SpoIVFB, that is responsible for cleaving pro-σK to its mature form. We also show that the SpoIVB PDZ domain is required for self-recognition and trans cleavage of SpoIVB and is probably also used to target an internal motif within the C-terminal region of SpoIVFA exposed in the space between the inner and outer forespore membranes. This work reveals the mechanism of intercompartmental signalling and provides a unified model as to how σK-directed gene expression in the mother cell is co-ordinated with events in the forespore chamber.
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  • 14
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: SpoIVB is essential for intercompartmental signalling in the σK-checkpoint of Bacillus subtilis. SpoIVB is synthesized in the spore chamber and is the signal which activates proteolytic processing of pro-σK to its mature and active form σK. We show here that SpoIVB is a serine peptidase of the SA clan. Expression of SpoIVB in Escherichia coli has shown that SpoIVB is able to self-cleave into at least three discrete products, and in vitro studies have shown cleavage in trans. Autoproteolysis of SpoIVB is tightly linked to the initiation of the two developmental functions of this protein, signalling of pro-σK processing and a yet, uncharacterized, second function which is essential for the formation of heat-resistant spores. In B. subtilis, SpoIVB is synthesized as a zymogen and is subject to two levels of proteolysis. First, autoproteolysis generating intermediate products, at least one of which is proposed to be the active form, followed by processing by one or more enzymes to smaller species. This could provide a mechanism for switching off the active SpoIVB intermediate(s) and suggests a similarity to other proteolytic cascades such as those found in blood coagulation.
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  • 15
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The process of spore formation in Bacillus subtilis is dependent upon a sophisticated program of gene expression that is regulated both temporally and spatially by a series of alternate sigma factors, in conjunction with a number of transcriptional regulators. One of these, SpoVT, regulates forespore-specific σG-dependent transcription and is related at the amino acid level to the major stationary phase sentinel, AbrB, whose mode of DNA recognition appears to be non-classical. Here, we report that the C-terminal domain of SpoVT is crucial to its correct folding and function, and how the DNA-binding domain from AbrB cannot complement the closely homologous domain of SpoVT in vivo. We also establish the oligomeric state of SpoVT and its component domains. Finally, we demonstrate that the regulation of transcriptional control by SpoVT is unexpectedly more complicated than its counterpart, AbrB, and that the latent non-specific DNA-binding activity of the N-terminal domain of SpoVT is modulated by the C-terminal domain, which perhaps in combination with another unknown factor, confers specificity.
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  • 16
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. o394-o395 
    ISSN: 1600-5368
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In the title compound, C14H21NO5S2, the imine group belonging to the tosylamide substituent occupies an axial position at the S atom of the thiane ring; the latter adopts a chair conformation. The torsion angle C(Ph)—S(O2)—N=S in the bridge between the two rings is −93.6 (2)° and the S—N=S bond angle is 122.15 (14)°.
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  • 17
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. o456-o457 
    ISSN: 1600-5368
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: All hydroxy groups on the parent compound, trehalose, have been substituted with acetate groups and the solvent of recrystallization, ethyl acetate, has been incorporated into the crystal lattice to give the title compound, C28H38O19·C4H8O2.
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  • 18
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. o77-o78 
    ISSN: 1600-5368
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In the title compound, C32H46O19·0.7H2O, all hydroxy groups on the parent compound, trehalose, have been substituted and some disordered bound water is located in the weakly diffracting crystal.
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  • 19
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Large-scale ecological surveillance data were analysed to determine the locations of apparent eutrophication effects across common British vegetation types between 1990 and 1998. Plant species composition was recorded from a total of 9514 fixed plots located in a stratified, random sample of 501 1 km squares across Britain. Changes in plant species composition along a gradient of substrate fertility were inferred from statistical tests of change in mean Ellenberg fertility value calculated for each fixed plot. Plots were grouped by eight vegetation types, five landscape features (hedges, road verges, watercourse banks, small biotopes, larger units in fields and unenclosed land) and six environmental zones. Tests of change in mean Ellenberg value were carried out on all combinations of these strata. Decision tree modelling was used to identify groups of test outcomes sharing the same direction of change and where each group was defined by a minimum number of strata. Post hoc power analysis was used to select statistically non-significant test outcomes that could be used to infer stability in the sampled sub-population.Out of a total of 142 tests of change in fertility value, 67% were increases, 8% were reductions and 25% indicated stability. The best overall predictor of increases in fertility value, and therefore of shifts in favour of plants suited to higher substrate fertility, was vegetation type. Irrespective of landscape feature and environmental zone, increased means were associated with infertile grasslands, moorland, upland woodlands and heath/bog. Already highly fertile grasslands and woodland assemblages in lowland Britain remained largely stable. The small number of decreasing test outcomes were associated with arable land in Scotland, Wales and western England. These patterns of change are hypothesized to reflect pervasive land-use drivers combined with the inherent responsiveness of the vegetation.
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  • 20
    ISSN: 1365-2516
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Recombinant factor VIIa (rfVIIa) has been widely used for the treatment and prevention of bleeding episodes in haemophiliacs with high-titre inhibitors. High single doses are the treatment of choice for joint and muscle bleeds in those patients. There are only a few reports on the value of rfVIIa in cirrhotic patients with haemostatic impairment but this drug can consistently correct the prothrombin time in these individuals. We report a case of a good response to a single high dose of rfVIIa in a patient with advanced liver disease who suffered from severe refractory postoperative haematuria.
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