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  • 2000-2004  (421)
  • 1925-1929
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  • 11
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 44 (2002), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Spo0A~P is the essential response regulator and transcription factor for sporulation initiation in Bacillus subtilis. The phosphorylation level of Spo0A in the cell is determined by the sensor kinase activity of the phosphorelay, donating phosphoryl groups, and the antagonistic effects of dephosphorylation mediated by the Rap and Spo0E families of phosphatases. In this study, spo0A mutations were generated that encoded proteins less sensitive to the activity of Spo0E than the wild-type protein. The Spo0A substitutions N12K, P60S, L62P and F88L are surface exposed and localize to the same face of the molecule as the active site and in its close proximity on the β1–α1, β3–α3 and β4–α4 loops. The corresponding surface in the Spo0F response regulator was shown previously to be involved in the interaction with the RapB phosphatase, as well as the KinA histidine kinase and the Spo0B phosphotransferase. Thus, residues occupying the same position (N12:Q12, F88:Y84) and the same loops in Spo0A or Spo0F are involved in the interaction with the structurally unrelated Spo0E and RapB phosphatases, respectively, in addition to kinases and phosphotransferase. The specificity in phosphatase target recognition must be the result of side-chain variability within the response regulators and the interactions they promote. The residues involved in Spo0E interaction are identical in all Spo0A orthologues from spore-forming Bacilli encoding Spo0E phosphatases.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    Journal of metamorphic geology 18 (2000), S. 0 
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Following the early Eocene collision of the Indian and Asian plates, intracontinental subduction occurred along the Main Central Thrust (MCT) zone in the High Himalaya. In the Kishtwar–Zanskar Himalaya, the MCT is a 2 km thick shear zone of high strain, distributed ductile deformation which emplaces the amphibolite facies High Himalayan Crystalline (HHC) unit south-westwards over the lower greenschist facies Lesser Himalaya. An inverted metamorphic field gradient, mapped from the first appearance of garnet, staurolite and kyanite index minerals, is coincident with the high strain zone. Petrography and garnet zoning profiles indicate that rocks in the lower MCT zone preserve a prograde assemblage, whereas rocks in the HHC unit show retrograde equilibration. Thermobarometric results derived using THERMOCALC indicate a P–T  increase of c. 180 °C and c. 400 MPa across the base of the MCT zone, which is a consequence of the syn- to postmetamorphic juxtaposition of M1 kyanite grade rocks of the HHC unit on a cooling path over biotite grade footwall rocks, which subsequently attain their peak (M2) during thrusting. Inclusion thermobarometry from the lower MCT zone reveals that M2 was accompanied by loading, and peak conditions of 537±38 °C and 860±120 MPa were attained. M1 kyanite assemblages in the HHC unit, which have not been overprinted by M2 fibrolitic sillimanite, were not significantly affected by M2, and conditions of equilibration are estimated as 742±53 °C and 960±180 MPa.There is no evidence for dissipative or downward conductive heating in the MCT zone. Instead, the primary control on the distribution of peak assemblages, represented by the index minerals, is postmetamorphic ductile thrusting in a downward propagating shear zone. Polymetamorphism and diachroneity of equilibration are also important controls on the thermal profile through the MCT zone and HHC unit.
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  • 13
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 1367-1367 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This talk will describe proposed studies of atomic- and nanoscale dynamics in condensed matter which take advantage of the high coherent x-ray flux to be produced by future x-ray free-electron laser (FEL) sources, such as the Linac Coherent Light Source at Stanford. In particular, I will focus on the current status and future prospects for photon correlation spectroscopy using coherent x-rays (XPCS), and the use of the ultrashort pulse structure of the x-ray FEL to observe dynamics into the femtosecond range. © 2002 American Institute of Physics.
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  • 14
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A technique for selective characterization of the structure of free and buried thin-film interfaces by vibrationally resonant sum frequency generation spectroscopy is described. Manipulation of Fresnel coefficients by choice of film thickness on a reflecting substrate allows simultaneous optimization of the signal from the desired interface and minimization of the signal from other interfacial sources. This technique is demonstrated for the free polystyrene (PS)/air and the buried PS/spin-on glass interfaces. Our spectra show that the pendant phenyl group orientation is similar at the buried and free interfaces, with the phenyls pointing away from the bulk PS at each interface.
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  • 15
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1809-1811 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present in situ surface x-ray scattering measurements of PbTiO3 epitaxy by metal–organic chemical-vapor deposition. Oscillations in crystal truncation rod intensity corresponding to layer-by-layer growth are observed under a variety of growth conditions. At lower PbO overpressures, we observe a transition to step-flow growth and an increased rate of recovery after growth, indicating a higher surface mobility. © 2002 American Institute of Physics.
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  • 16
    Electronic Resource
    Electronic Resource
    Oxford, UK and Boston, USA : Blackwell Publishers
    Financial accountability and management 16 (2000), S. 0 
    ISSN: 1468-0408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: We examine boards of directors of medical research charities and find that medical charities spend less on program activities and more on fund-raising when the executive director of the charity serves on the board of directors, especially when the board is small. Executive salaries are also higher at charities where management is represented on the board. Management and general expenses and fund balances are, however, unrelated either to the presence of an insider on the board or to the size of the board.
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  • 17
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Weed research 44 (2004), S. 0 
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Classical Mendelian experiments were conducted to determine the genetics and inheritance of quinclorac and acetolactate synthase (ALS)-inhibitor resistance in a biotype of Galium spurium. Plants were screened with the formulated product of either quinclorac or the ALS-inhibitor, thifensulfuron, at the field dose of 125 or 6 g active ingredient (a.i.) ha−1 respectively. Segregation in the F2 generation indicated that quinclorac resistance was a single, recessive nuclear trait, based on a 1 : 3 segregation ratio [resistant : susceptible (R : S)]. Resistance to ALS inhibitors was due to a single, dominant nuclear trait, segregating in the F2 generation in a 3 : 1 ratio (R : S). The genetic models were confirmed by herbicide screens of F1 and backcrosses between the F1 and the S parent. F2 plants that survived quinclorac treatment set seed and the resulting F3 progeny were screened with either herbicide. Quinclorac-treated F3 plants segregated in a 1 : 0 ratio (R : S), hence F2 progenitors were homozygous for quinclorac resistance. In contrast, F3 progeny segregated into three ratios: 1 : 0, 3 : 1 and 0 : 1 (R : S) in response to ALS-inhibitor treatment. This segregation pattern indicates that their F2 parents were either homozygous or heterozygous for ALS-inhibitor resistance. Therefore, there were clearly two distinct resistance mechanisms encoded by two genes that were not tightly linked as demonstrated by segregation patterns of the F3.
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  • 18
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of mycorrhizal infection, soil P availability and fruit production on the male function of reproduction were examined in two cultivars of tomato (Lycopersicon esculentum Mill.). Tomato plants were grown in a greenhouse under three treatment combinations: non-mycorrhizal, low P (NMPO); non-mycorrhizal, high P (NMP3); and mycorrhizal, low P (MPO). In addition, all treatment combinations were grown both with and without fruit. Fruit production decreased final leaf biomass, flower production and in vitro pollen tube growth rates, often reducing the beneficial effects of increased P uptake. Thus, fruit production diverted resources from subsequent vegetative growth, flower production and pollen development. As the growing season progressed, mean pollen production per flower and in vitro germination and tube growth decreased. Mycorrhizal infection and high soil P conditions increased final leaf biomass, flower production, mean pollen production per flower (in one cultivar) and in vitro pollen tube growth rates. Thus, mycorrhizal infection and high soil P conditions increased pollen quantity and quality, thereby enhancing fitness through the male function. Similar trends in these treatments suggested that mycorrhizal effects on the male function were largely the result of improved P acquisition.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 123 (2004), S. 0 
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Broccoli is well recognized as a source of glucosinolates and their isothiocyanate breakdown products. Glucoraphanin is one of the most abundant glucosinolates present in broccoli and its cognate isothiocyanate is sulphoraphane, a potent inducer of mammalian detoxication (phase 2) enzyme activity and anti-cancer agent. This study was designed to measure: glucosinolate levels in broccoli florets from an array of genotypes grown in several environments; the elevation of a key phase 2 enzyme, quinone reductase, in mammalian cells exposed to floret extracts; and total broccoli head content. There were significant environmental and genotype-by-environment effects on levels of glucoraphanin and quinone reductase induction potential of broccoli heads; however, the effect of genotype was greater than that of environmental factors. The relative rankings among genotypes for glucoraphanin and quinone reductase induction potential changed, when expressed on a per head basis, rather than on a concentration basis. Correlations of trait means in one environment vs. means from a second were stronger for glucoraphanin and quinone reductase induction potential on a per head basis than on a fresh weight concentration basis. Results of this study indicate that development of a broccoli phenotype with a dense head and a high concentration of glucoraphanin to deliver maximum chemoprotective potential (high enzyme induction potential/glucoraphanin content) is a feasible goal.
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  • 20
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Publishing Ltd.
    Plant species biology 19 (2004), S. 0 
    ISSN: 1442-1984
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Solanum carolinense has a gametophytic self-incompatibility (GSI) system that is typical of the Solanaceae in which pistils produce specific S-RNase proteins that disrupt the growth of pollen tubes sharing the same S-allele. However, unlike most self-incompatible plants Solanum carolinense is a weed. Self-incompatibility is uncommon in weeds because disturbed habitats require frequent recolonization (hence populations are repeatedly founded by few individuals bearing a limited number of S-alleles), effective population sizes are small (supporting few S-alleles) and habitats are ephemeral (so there is limited time for the migration of additional S-alleles into populations). We carried out a series of greenhouse experiments using clonal replicates (rhizome cuttings) of plants from two natural populations of S. carolinense to determine if there is variation in the strength of GSI within these populations. We found that the growth rate of self-pollen tubes and self-fertility increases with floral age. That is, flowers become more self-compatible as they age. Moreover, we found that self-fertility increases on plants in which the first 20 flowers receive no cross pollen. That is, when few or no fruits are produced on the first 20 flowers, self-pollination is more likely to result in fruit/seed set. Finally, we found that genotypes differ in their degree of self-fertility indicating that there is broadsense heritability for plasticity in the strength of self-incompatibility. These findings indicate that some genotypes of S. carolinense are capable of producing self-seed when cross pollen is scarce, even though the plants have a functional GSI system.
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