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  • 1
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0983
    Keywords: Multidrug resistance ; Candida albicans ; Saccharomyces cerevisiae ; ABC transporters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By functional complementation of a PDR5 null mutant of Saccharomyces cervisiae, we have cloned and sequenced the multidrug-resistance gene CDR1 of Candida albicans. Transformation by CDR1 of a PDR5-disrupted host hypersensitive to cycloheximide and chloramphenicol resulted in resistance to cycloheximide, chloramphenicol and other drugs, such as the antifungal miconazole, with collateral hypersensitivity to oligomycin, nystatin and 2,4 dinitrophenol. Our results also demonstrate the presence of several PDR5 complementing genes in C. albicans, displaying multidrug-resistance patterns different from PDR5 and CDR1. The nucleotide sequence of CDR1 revealed that, like PDR5, it encodes a putative membrane pump belonging to the ABC (ATP-binding cassette) superfamily. CDR1 encodes a 1501-residue protein of 169.9 kDa whose predicted structural organization is characterized by two homologous halves, each comprising a hydrophobic region with a set of six transmembrane stretches, preceded by a hydrophilic nucleotide binding fold.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 9 (1987), S. 132-140 
    ISSN: 0392-6737
    Keywords: Electromagnetic wave propagation in plasma ; Antennas in plasma ; plasma-filled wave guides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Si è studiata la propagazione delle onde elettromagnetiche in una guida d’onda su un piatto parallelo con un limite ondulato e riempiti con un plasma caldo uniassiale in movimento. Sono state derivate la relazione di dispersione e le espressioni di campo per i modi TM. Sono stati studiati in dettaglio gli effetti della temperatura e la velocità di spostamento sui modi di propagazione. Le onde veloci e lente sono grandemente influenzate dalla temperatura e dalla velocità di spostamento, mentre la guida d’onda è influenzata in maniera non significativa. È anche stato discusso l’effetto dell’ondulazione. Si deriva la relazione di dispersione dei modi TE in questo caso e si trova che essa è la stessa della guida d’onda riempita con spazio libero.
    Abstract: Резюме Исследуется распространение электромагнитных волн в волноводе с параллельными пластинами, имеющем одну гофрированную границу и заполненном одноосной нагретой дрейфующей плазмой. Выводятся дисперсионное соотношение и полевые выражения для TM-мод. Подробно изучается влияние температуры и скорости дрейфа на распространение мод. Температура и скорость дрейфа сильно влияют на быстрые и медленные волны, тогда как влияние на волну волновода является незначительным. Также обсуждается эффект гофрирования. В этом случае выводится дисперсионное соотношение для TE-мод и получается тот же результат, как в случае волновода с пустым пространством.
    Notes: Summary The e.m. wave propagation in a parallel-plate wave guide withone boundary corrugated and filled with uniaxial warmdrifting plasma has been studied. The dispersion relation and the field expressions for the TM-modes have been derived. The effects of the temperature and the drift velocity on the propagation modes have been studied in detail. The fast and the slow waves are greatly affected by the temperature and the drift velocity, whereas the wave guide wave is insignificantly affected. The effect of the corrugation has also been discussed. The dispersion relation of the TE-modes, in this case, has been derived and found to be same as that of the wave guide filled with free space.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 9 (1987), S. 1389-1396 
    ISSN: 0392-6737
    Keywords: Electromagnetic wave propagation in plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Si è studiata la propagazione di onde elettromagnetiche in una guida d'onda piano parallela con contorno corrugato, riempita con plasma isotropico disperdente calore. Si deducono le relazioni di dispersione e le espressioni di campo per i modi TE e TM. Entrambi i modi sono influenzati dalla presenza del corrugamento. Le caratteristiche del modo TM sono state analizzate in dettaglio usando un diagramma frequenza-costante di fase con velocità di deriva e temperatura come parametri. I modi TM sono influenzati in maniera significativa dalla velocità di deriva e dalla temperatura del plasma, mentre i modi TE rimangono inalterati.
    Abstract: Резюме Исследуется распространение электромагнитных волн в волноводе с одной гофрированной поверхностью, заполненном изотропнои теплой дрейфующей плазмой. Выводятся дисперсионные соотношения и выражения для поля в случае TE и TM мод. Наличие рифленой поверхности влияет на обе моды. Подробно анализируются характеристики TM моды, используя частотно-фазовую диаграмму, причем дрейфовая скорость и температура рассматриваются как параметры. Дрейфовая скорость и температура плазмы существенно влияют на TM моды, тогда как TE моды остаются без изменения.
    Notes: Summary The propagation of electromagnetic waves in one boundary-corrugated parallel-plate waveguide filled with isotropic warm drifting plasma has been investigated. The dispersion relations and the field expressions for the TE and the TM modes have been derived. Both the modes are affected by the presence of corrugation. The characteristics of the TM mode have been analysed in detail using frequency-phase constant diagram with drift velocity and temperature as parameters. The TM modes are significantly affected by the drift velocity and temperature of the plasma, while the TE modes remain unaffected.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 84 (1991), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Phosphate uptake studies in different strains of the dimorphic pathogenic yeast Candida albicans were undertaken to show that this yeast actively transported phosphate with an apparent Km in the range of 90–170 μM. The uptake was pH dependent and derepressible under phosphate starvation. Vanadate-resistant (van) mutants of C. albicans showed a 20–70% reduction in the rate of phosphate uptake in high phosphate medium and was associated with an increased Km and reduced Vmax. The magnitude of depression under phosphate starvation was different between van mutants. These results demonstrate that van mutants may have developed resistance by modifying the rate of entry of vanadate.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 114 (1993), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The primary mode of action of azoles is the inhibition of cytochrome P-450 dependent 14α-demethylase, a key enzyme in ergosterol biosynthesis in fungi. Our results demonstrated that Candida albicans cells grown in the presence of 10 μg ml−1 of miconazole (miconazole-grown), do not possess ergosterol in their plasma membranes and this ergosterol depletion leads to a drastic change in membrane fluidity as shown by fluorescence polarization measurements and unsaturation index. There was an increase in membrane order in miconazole-grown cells and a reduced rate of uptake of amino acids. We also checked for membrane permeability changes in normal mid-log phase cells (normal-grown) in short incubations (10 min) with 10 μg ml−1 miconazole (miconazole-incubated). Interestingly, the amino acid uptake rates except that Gly were not affected significantly in these cells. The results suggest that in the miconazole-incubated cells, the drug is not able to alter the level of ergosterol of inhibit ergosterol biosynthesis during 10 min incubation and therefore the interaction of the drug neither leads to significant disorganization of membrane components, nor affects permease activity, whereas in the miconazole-grown cells there is ergosterol depletion leading to accumulation of biosynthetic intermediates, resulting in membrane rearrangement thereby causing a major fluidity change. This fluidity change may explain the drastic reduction of amino acid transport in miconazole-grown cells. To investigate whether the reduction in amino acid transport was only due to change in membrane fluidity, as a consequence of absence of ergosterol, the PM-ATPase activity was checked in the miconazole-grown cells and was found to be unaffected, which suggests that changes in amino acid uptake were due to change in membrane fluidity.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 79 (1991), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Amino acid uptake studies in Azotobacter vinelandii were undertaken to determine whether absence of uptake could be a possible reason for the difficulty in isolating auxotrophic mutants in this organism. A. vinelandii cells were found to be capable of transporting amino acids via an active mechanism. Kinetic studies with four amino acids and respiratory inhibitors confirmed the presence of energy dependent amino acid uptake systems. The Kt values for l-glutamate, l-alanine, l-cysteine and l-lysine were 10, 23, 91 and 233 μM, respectively. Incorporation of amino acids into trichloroacetic acid precipitable fractions further confirmed that the transported amino acids were incorporated into proteins. Thus the lack of at least some classes of amino acid auxotrophs of A. vinelandii is probably not because of poor transport of amino acids.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 38 (1973), S. 1004-1010 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 176 (1999), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We previously demonstrated that the CDR1 gene, encoding a multidrug transporter in Candida albicans, is differentially upregulated by various drugs and steroids. In order to get an insight into the molecular basis of the induction of this gene we analyzed its promoter region. The transcription start site was mapped to 63 nucleotides upstream of the initiating ATG. Reporter assays revealed the presence of four upstream activating and four upstream repressing sequence domains along the entire promoter. Like the native gene, promoter-luciferase recombinants showed enhanced activity in response to various stresses like drugs, human steroid hormones and heavy metals. Mutational analysis demonstrated that while the proximal promoter (−345/+1) contains all the regulatory domains required for its induction by various other stresses, the miconazole response is mediated via the distal promoter (−857/−1147), harboring an AP-1 site. The involvement of the AP-1 element in mediating the latter effect was evident by an increase in AP-1 binding activity following miconazole treatment.
    Type of Medium: Electronic Resource
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