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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant pathology 44 (1995), S. 0 
    ISSN: 1365-3059
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Mycelial growth, polyamine concentrations and the activities of enzymes of polyamine biosynthesis and catabolism were examined in Phytophthora infestans and Pythium ultimum grown in the presence of difluoromethylornithine (DFMO), an inhibitor of omithine decarboxylase (ODC), and difluoro-methylarginine (DFMA), an inhibitor of arginine decarboxylase (ADC). Growth of P. infestans was reduced by DFMO and a mixture of DFMO + DFMA, but was increased by DFMA at concentratiotis of 5 MM and greater, Polyamine concentrations and ODC activity were significantly reduced in P. infestans grown on all inhibitor treatments. In contrast, growth, polyamine concentrations and enzyme activities were not affected in P, ultimum exposed to the inhibitors.It seems unlikely that P. infestans and P. uttimum possess ADC activity, as neither of the products of ADC activity (agmatine and putrescine) could be detected in ADC assays. Although ODC from P. infestans was sensitive to DFMO, ODC from P. uttimum was insensitive to the inhibitor. Moreover, uptake of DFMO by P. infestans was three times greater than that observed by P. ultimum.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Intra- and inter-sample similarities for four populations of the annual grass weed Phalaris minor from Haryana state, India, were examined using inter-simple sequence repeat (ISSR) DNA markers. Levels of polymorphism within and between populations were low in comparison with values reported from other grassy weed species. Analysis of inter-population similarities allowed a partial differentiation of the four populations and of pairs of populations classified by cropping system. Analysis of the intra-population similarity data showed a weak but consistent and statistically significant negative correlation between the molecular similarity of seedlings and the physical distance between their mother plants over distances up to 40 m (the maximum separation tested) in all four populations. The consistency of the observed relationship between molecular similarity and physical separation, and the differences in cultivation practices at the four sites, suggested that the relationship may be a result of localized out-crossing, rather than an effect of localized seed rain. The results of the analyses are discussed in relation to the potential for evolution of multiple traits in the weed in response to changes in the wheat production system in the region.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 160-164 
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The structure of a tetragonal crystal of bovine pancreatic RNase B complexed with d(pA)4 was determined by molecular replacement and difference Fourier methods. This crystal belongs to space group P41212 and has unit-cell dimensions a = b = 44.5, c = 156.5 Å. The model consists of the enzyme and a tetranucleotide with fractional occupancies, suggesting multiple modes of oligonucleotide binding. It does not include any polysaccharide residues or solvent molecules. After refinement at 2.7 Å, the R value was 0.163 with acceptable stereochemistry. The model illustrates a set of well defined interactions for substrate binding, particularly between the central dinucleotide and the enzyme.
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 256-261 
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Xylanase from the bacterial plant pathogen Erwinia chrysanthemi (E.C. 3.2.1.8), expressed in E. coli, has been crystallized for X-ray diffraction analysis both in the presence and the absence of its polymeric substrate 4-O-methyl glucuronoxylan. In all cases it was found that the quality, time of appearance, and reproducibility of both the native and complex crystals were significantly enhanced by heating of the protein to 323 K prior to dispensing the crystallization trials. Crystals of the native protein are ideal for X-ray diffraction analysis, producing Bragg reflections beyond 1.5 Å resolution with virtually no degradation with time. The native crystals are in space group P21, with a = 39.33, b = 49.46, c = 90.85 Å and β = 101.58°. Other polymorphs have also been obtained and their cell parameters determined. Crystallization of the enzyme in the presence of polymeric substrate yields two distinctly different crystals at different concentrations of the xylan. These are thought to be complexes of the protein with stable products of the enzymatic reaction. A similar result had been obtained previously with pancreatic α-amylase and its substrate glycogen.
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  • 5
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 724-733 
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The protein thaumatin was studied as a model macromolecule for crystallization in microgravity-environment experiments conducted on two US Space Shuttle missions (USML-2 and LMS). In this investigation, we have evaluated and compared the quality of space- and earth-grown thaumatin crystals using X-ray diffraction analyses, and characterized them according to crystal size, diffraction resolution limit and mosaicity. Two different approaches for growing thaumatin crystals in the microgravity environment, dialysis and liquid–liquid diffusion, were employed as a joint experiment by our two investigative teams. Thaumatin crystals grown in a microgravity environment were generally larger in volume and the total number of crystals was less, relative to crystals grown on earth. They diffracted to significantly higher resolution and with improved diffraction properties, as judged by relative plots of I/σ versus resolution. The mosaicity of space-grown crystals was significantly less than that of crystals grown on earth. Increased concentrations of protein in the crystallization chambers in microgravity led to larger crystals. The data presented here lend further support to the idea that protein crystals of improved quality can be obtained in a microgravity environment.
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  • 6
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 28 (1995), S. 362-365 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A persistent problem in macromolecular crystallization is that of the promotion of easily and rapidly grown microcrystals to a size and quality sufficient for X-ray diffraction analysis. This is often true even for highly purified proteins, viruses and nucleic acids where recrystallization shows no benefit. It has been found that in some cases larger and better-formed crystals can be grown by graduated finely sampled screens of pH at high values in the neighborhood of 8.5, and at low values around 4.0. This was shown to be quite crucial for the crystallization of several proteins. It is suggested that this approach may owe its success to the precise manipulation of the protonation state of only a few critical carboxyl and basic side chains essential in the formation of intermolecular salt bridges.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 143 (1996), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract In the light leaf spot fungus Pyrenopeziza brassicae, the kinetics of uptake of sucrose, glucose and fructose are all biphasic. At low and high concentrations, glucose and fructose share a high-affinity and a low-affinity hexose carrier respectively, with Kms of 3.5 and 4.6 μM for uptake of glucose and fructose respectively by the high-affinity system, and Kss of 690 and 750 uM for uptake of glucose and fructose by the low-affinity system. The data also suggest the existence of separate high-affinity and low-affinity uptake systems for sucrose. P. brassicae possesses both soluble and paniculate invertase activity, with pH optima of 5.0 and 4.0 respectively. Activity of the particulate invertase is considerably in excess of the highest rates of sucrose uptake.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0649
    Keywords: PACS: 42.60 b–d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 19  W/cm2 range with improved shot-to-shot energy stability. This system gives a resulting brightness of ∼3.3×1021 W cm-2 sr-1.
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  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature structural biology 2 (1995), S. 956-959 
    ISSN: 1072-8368
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The growth of six protein and virus crystals was investigated in situ using atomic force microscopy. Most of the crystals grew principally on steps generated by two-dimensional nucleation on surfaces though some grew by development of spiral dislocations. Apoferritin grew by a rarely encountered ...
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  • 10
    Publication Date: 2009-12-28
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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