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  • 1
    Electronic Resource
    Electronic Resource
    Influence of gene dosage and autoregulation of the regulatory genes INO2 and INO4 on inositol/choline-repressible gene transcription in the yeast Saccharomyces cerevisiae (1997)
    Springer
    Current genetics 31 (1997), S. 462-468 
    Details
    ISSN: 1432-0983
    Keywords: Key words Transcriptional regulation ; Phospholipid biosynthesis ; Saccharomyces cerevisiae ; INO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of structural genes of phospholipid biosynthesis in yeast is mediated by the inositol/choline-responsive element (ICRE). ICRE-dependent gene activation, requiring the regulatory genes INO2 and INO4, is repressed in the presence of the phospholipid precursors inositol and choline. INO2 and, to a less extent, INO4 are positively autoregulated by functional ICRE sequences in the respective upstream regions. However, an INO2 allele devoid of its ICRE functionally complemented an ino2 mutation and completely restored inositol/choline regulation of Ino2p-dependent reporter genes. Low-level expression of INO2 and INO4 genes, each under control of the heterologous MET25 promoter, did not alter the regulatory pattern of target genes. Thus, upstream regions of INO2 and INO4 are not crucial for transcriptional control of ICRE-dependent genes by inositol and choline. Interestingly, over-expression of INO2, but not of INO4, counteracted repression by phospholipid precursors. Possibly, a functional antagonism between INO2 and a negative regulator is the key event responsible for repression or de-repression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002940050231
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  • 2
    Electronic Resource
    Electronic Resource
    Involvement of MAP-kinases and -phosphatases in uptake and intracellular replication of Listeria monocytogenes in J774 macrophage cells (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 157 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In this study we show that protein tyrosine kinases and also protein tyrosine phosphatases are involved in the uptake of Listeria monocytogenes by J774 macrophages to a different extent than in the uptake of inert latex beads. In addition, protein tyrosine kinases are necessary for the intracellular growth and survival of L. monocytogenes. The expression of the MAP kinase phosphatase MKP-1, a protein tyrosine phosphatase, is induced upon infection, and phagocytosis of L. monocytogenes by J774 cells overexpressing the MKP-1 protein is reduced compared to control cells. The decreased phagocytosis of L. monocytogenes as a result of the MKP-1 overexpression in J774 macrophages suggests that the activation of the MAP kinase(s) ERK-1 and/or ERK-2 is an essential requirement for the uptake of L. monocytogenes by J774 macrophages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb12763.x
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamics of hydrogen-bonded liquids confined to mesopores: A dielectric and neutron spectroscopy study (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 2016-2024 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we present and discuss experimental results on molecular mobility in propylene glycol and its three oligomers confined to the ∼100 A(ring) pores of a controlled porous glass. The objective is to elucidate the finite size effects on the dynamics of hydrogen-bonded liquids of different molecular weights but identical chemical composition. The methods of dielectric and neutron spectroscopy have been employed to investigate both the low- and high-frequency features as a function of temperature. We find that all fluids in pores separate into two distinct liquid phases. (i) molecules physisorbed at the surface which exhibit a dramatic frustration of their mobility related to a substantial positive shift of the glass transition temperature Tg by up to ΔTg≈+47 K; and (ii) relatively "free'' molecules in the inner pore space subject to only moderate retardation of the α and normal mode relaxation and substantial broadening of the distribution of relaxation times. The shift in Tg for the α process with ΔTg≈+5 K is maximal for the monomer liquid and gradually diminishes with increasing molecular weight or decreasing intermolecular hydrogen bonding. The inelastic neutron spectrum of confined propylene glycol shows the boson peak as expected in bulk strong and intermediate glass formers in the vicinity of Tg. This effect can be attributed to the finite-size induced crossover from long wave vibrations characteristic of a continuous medium to localized vibrations in a confined geometry. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469728
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  • 4
    Electronic Resource
    Electronic Resource
    The electron cyclotron absorption diagnostic at the Rijnhuizen tokamak project (1997)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 4439-4447 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new 20-channel electron cyclotron absorption diagnostic has been developed at the Rijnhuizen tokamak project. It is the first time the electron pressure profile in a tokamak plasma can be measured directly with a time resolution of 1 ms. The diagnostic measures simultaneously the emission and absorption of the second harmonic electron cyclotron frequencies. Microwaves are injected from the high field side and detected at the low field side in the equatorial midplane. The transmitted power is measured after a single pass through the plasma column. The absorption measurements are complicated by nonresonant losses: refraction of the injected microwaves (losses up to 100%), and scattering of microwaves by density fluctuations (losses 2%–3%). A fast algorithm has been developed to obtain a quantitative measure for these nonresonant losses. This calculation method is based on a parametrization of the experimental data. Combining the electron cyclotron absorption (ECA) measurements and the parametrization provides a reliable tool for determining the optical depth, the electron temperature, and the electron pressure. A good agreement was found between pressure and temperature profiles, measured with ECA and other diagnostics. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148411
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  • 5
    Electronic Resource
    Electronic Resource
    Investigation of ion sawtooth activity by Rutherford scattering : Proceedings of the tenth topical conference on high temperature plasma diagnostics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 327-329 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The Rutherford scattering diagnostic at TEXTOR has been used to investigate the time evolution of the ion velocity distribution during sawtooth activity. Coherent averaging techniques have been employed to obtain better statistics. The time evolutions of central ion and electron density were found to be strongly correlated in four out of five cases. In one case, where saturation of the sawteeth occurred, a discrepancy between the two has been found, which could be attributed to an influx of impurities towards the end of the sawtooth. Changes of about 20% in the central toroidal rotation of the bulk ions have been found during sawtooth crashes of neutral beam injected discharges, whereas no changes were found in the ohmic case. No statistically reliable statements can be made about changes in the ion temperature. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146401
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  • 6
    Electronic Resource
    Electronic Resource
    Transcriptional control of the yeast acetyl-CoA synthetase gene, ACS1, by the positive regulators CAT8 and ADR1 and the pleiotropic repressor UME6 (1997)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 26 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The ACS1 gene, encoding one out of two acetyl-CoA synthetase isoenzymes of Saccharomyces cerevisiae, is strictly regulated at the transcriptional level by the carbon source of the medium. While ACS1 is poorly expressed in the presence of a high glucose concentration, a several hundred-fold derepression occurs with ethanol as the sole carbon source or under conditions of sugar limitation. The molecular mechanism responsible for the carbon source control of ACS1 turned out to be highly complex. A carbon source-responsive element (CSRE), previously identified upstream of gluconeogenic structural genes, and a binding site of the alcohol dehydrogenase regulator, Adr1p, together mediate about 80% of the derepressed gene activity. Binding of Adr1p synthesized by Escherichia coli to the ACS1 control region was shown by an electrophoretic mobility shift assay. In addition to these activating elements, two URS1 motifs confer negative control on the ACS1 promoter. The URS1 element was found to be a constitutive repression site, which is most effective from a downstream position with respect to an upstream activation site (UAS). In a mutant lacking the URS1-binding factor, Ume6p, ACS1 expression was partially glucose insensitive. Ume6p must counteract transcription factors that are constitutively active. Site-directed mutagenesis of Abf1p binding sites in the ACS1 promoter significantly reduced gene expression in the ume6 mutant, grown under repressing conditions. Thus, a functional balance of the pleiotropic positive factor Abf1p and the negative factor Ume6p is in part responsible for glucose repression of ACS1. The combined influence of the regulated UAS elements, CSRE and Adr1p binding site, mediates a strong increase in ACS1 expression under derepressing conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.5611937.x
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  • 7
    Electronic Resource
    Electronic Resource
    Constitutive and carbon source-responsive promoter elements are involved in the regulated expression of the Saccharomyces cerevisiae malate synthase gene MLS1 (1997)
    Springer
    Molecular genetics and genomics 255 (1997), S. 619-627 
    Details
    ISSN: 1617-4623
    Keywords: Key wordsSaccharomyces cerevisiae ; Gluconeogenesis ; Malate synthase ; Transcriptional regulation ; MLS1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The malate synthase gene, MLS1, of the yeast Saccharomyces cerevisiae is transcriptionally regulated by the carbon source in the growth medium. A MLS1-lacZ fusion gene, expressed at a basal level in the presence of 2% glucose, is derepressed more than 100-fold under conditions of sugar limitation. No evidence for MLS1 induction by oleic acid was found. By deletion analysis of the MLS1 control region, we identified two sites, UAS1 and UAS2, as important for efficient derepression of the gene. Both sites contain sequences that resemble the previously characterized carbon source-responsive element (CSRE) found in the promoter of the isocitrate lyase gene ICL1. Indeed, UAS1 and UAS2 in the MLS1 upstream region turn out to be functional CSRE sequence variants. This finding allowed us to define a modified version of the CSRE consensus sequence (CCRTYSRNCCG). Protein binding to UAS1MLS1 was observed with extracts from derepressed but not from repressed cells, and could be competed for by an excess of the unlabelled CSRE(ICL1) sequence. No competition was observed with a mutated CSRE variant. Site-directed mutagenesis of both CSREs in the MLS1 promoter reduced gene activation under derepressing conditions to 20% of the wild-type level. The same decrease was observed with the wild-type MLS1 promoter in a cat8 mutant, lacking an activator of CSRE-dependent transcription. The CSRE/Cat8p-independent activation of MLS1 is mediated by constitutive UAS elements. The pleiotropic transcription factor Abf1p, which binds to the MLS1 upstream region, may contribute to constitutive activation. Thus, in order to ensure the severe glucose repression of MLS1 observed, repressor elements that respond to the carbon source must counteract constitutive activation. In summary, ICL1 and MLS1 share common cis-acting elements, although a distinct mechanism of carbon source control also contributes to MLS1 regulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050536
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of pollen competitive environment on pollen performance in Mirabilis jalapa (Nyctaginaceae) (1997)
    Springer
    Sexual plant reproduction 10 (1997), S. 101-106 
    Details
    ISSN: 1432-2145
    Keywords: Key words Pollen ; Pollen competition ; Pollen performance ; Microgametophyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We examined the influence of pollen competitive environment on pollen performance in Mirabilis jalapa. We used the number of pollen grains and the number of pollen tubes per pistil as measures of pollen competition. Pollen germination, pollen tube penetration into the style, and pollen tube growth rates were used as measures of pollen performance. All three measures of pollen performance were affected by the competitive environment. Pollen germination was greatest at intermediate pollen load sizes. The percentage of germinated pollen grains that penetrated the stigma and grew into the style decreased with pollen load size. Pollen tube growth rate in the style was greater and more variable with larger numbers of pollen tubes in the style. Controlling for the degree of selection at the stigma indicated that pollen-pollen or pollen-style interactions were the likely causes of increased growth rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050074
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  • 9
    Electronic Resource
    Electronic Resource
    Reliability-Based Optimization of structural systems (1997)
    Springer
    Mathematical methods of operations research 46 (1997), S. 287-307 
    Details
    ISSN: 1432-5217
    Keywords: Reliability-based optimization ; structural reliability ; cost function ; nonlinear programming ; Monte Carlo simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract A method to carry out a Reliability-Based Optimization (RBO) of especially nonlinear structural systems is introduced. Statistical uncertainties involving both structural and loading properties are considered. The concept is based on the separation of structural reliability analyses and the optimization procedures. Two approaches are discussed, depending on the interaction of reliability analysis and mathematical programming and the way of representation of the limit state functions (LSF) of the structure. As, for cases of practical significance, the LSF is known only pointwise it is approximated by Response Surfaces (RS). For the response calculations Finite Element (FE) procedures are utilized. Failure probabilities are determined by applying variance reducing Monte Carlo simulation (MCS) techniques such as Importance Sampling (IS). Following the reliability analysis, the optimization procedure is controlled by the NLPQL algorithm. A numerical example in terms of a template ocean platform exemplifies the procedures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01194858
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  • 10
    Electronic Resource
    Electronic Resource
    Cloning and DNA sequence analysis of pepQ, a prolidase gene from Lactobacillus delbrueckii subsp. lactis DSM7290 and partial characterization of its product (1995)
    Springer
    Molecular genetics and genomics 247 (1995), S. 494-500 
    Details
    ISSN: 1617-4623
    Keywords: Prolidase ; Metalloprotease ; Lactobacillus delbrueckii subsp. lactis ; Nucleotide sequence analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From a genomic library of Lactobacillus delbrueckii subsp. lactis (DSM7290) DNA, in the low-copy-number vector pLG339, a recombinant clone was selected, which complemented a mutation in the prolidase gene (pepQ) of Escherichia coli UK173. Nucleotide sequence analysis revealed an open reading frame of 1104 nucleotides corresponding to a protein of 368 amino acids with a calculated pI of 4.64 and a molecular mass of 41087 Da. The start site of pepQ transcription was determined by primer extension analysis with mRNA prepared from L. delbrueckii. Based on homology of the gene product to various peptidases and on the substrate specificity determined, the peptidase was designated PepQ. The influence of various protease inhibitors and cations on peptidase activity indicated that PepQ is a metalloprotease. The absence of a membrane-spanning domain and a signal peptide sequence argues for a cytoplasmic localization of the enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293152
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