Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 0749-503X
    Keywords: cell walls ; protease ; β-glucanase ; lysis ; yeast ; antifungal drugs ; glucan ; mannoprotein ; S. cerevisiae ; C. albicans ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The rate of formation of spheroplasts of yeast can be used as an assay to study the structural integrity of cell walls. Lysis can be measured spectrophotometrically in hypotonic solution in the presence of Zymolyase, a mixture of cell wall-digesting enzymes. The optical density of the cell suspension decreases as the cells lyse. We optimized this assay with respect to enzyme concentration, temperature, pH, and growth conditions for several strains of Saccharomyces cerevisiae. The level of variability (standard deviation) was 1-5% between trials where the replications were performed on the same culture using enzyme prepared from the same lot, and 5-15% for different cultures of the same strain. This assay can quantitate differences in cell wall structure (1) between exponentially growing and stationary phase cells, (2) among different S. cerevisiae strains, (3) between S. cerevisiae and Candida albicans, (4) between parental and mutated lines, and (5) between drug- or chemically-treated cells and controls. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dense films of poly[(4-ethylphenoxy)(phenoxy)phosphazene] (PEPP), a potentially attractive ion-exchange membrane material, were crosslinked to varying degrees using UV light and a photoinitiator. This polymer contained two kinds of substituents: phenoxy groups to be used for possible functionalization (e.g., sulfonation) and ethylphenoxy side-chains for photocrosslinking, where hydrogens at the benzylic carbons could be abstracted by a photoinitiator-leaving macroradicals that after recombination formed covalent bonds. The polyphosphazene polymer was synthesized, mixed with a photoinitiator, shaped into a thin film by solvent casting, and irradiated with UV light for a specified period of time. Benzophenone (BP), was selected as the photoinitiator because it was miscible with poly-phosphazene, had the highest rate of hydrogen abstraction, and absorbed UV light of 365 nm wavelength. The half-life of benzophenone in 50 μm-thick irradiated films was determined to be 20 min. When the BP-PEPP molar ratio was increased from 0 to 0.5, the glass transition temperature increased after irradiation from -8.8 to 53.5°C. At the same time, the equilibrium swelling in dimethylacetamide, at 25°C, decreased from infinity to 0.31. Tensile strength tests of the crosslinked films revealed a nonlinear dependence on BP-PEPP molar ratio. © 1996 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0887-6266
    Keywords: polyamide chains in solution, thermal flexibility of ; intrinsic viscosity of poly(p-phenylene terephthalamide) and poly(m-phenylene isophthalamide) of equal molecular weights, temperature dependence of ; flexibility mechanism for polyamide chains in solution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Intrinsic viscosities of poly(p-phenylene terephthalamide) (PPTA) and poly(m-phenylene isophthalamide) (PMIA) samples of the same molecular weight are determined in 90%, 96% and 100% sulfuric acid at temperatures from 0 to 130°C. Conditions are established under which the degree of coiling of PPTA molecule is close to that for PMIA. Experimental data are compared with the results of theoretical calculations of the Kuhn segment length. In the light of this comparison, some quantitative characteristics of the deformational flexibility mechanism for aromatic polyamide chains and the hindrance to intramolecular rotation are discussed. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0959-8103
    Keywords: Polydiacetylene ; thermal analysis ; 13C NMR ; chromism ; fluorescence ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polydiacetylene (2) of varying molecular weight has been formed by UV- or 60Co γ-irradiation of the diacetylene PhCH2CO2(CH2)9-C≡C—C≡C(CH2)9O2CCH2Ph (3), with conversion of 30-〉95%. Samples of (2) with differing physical properties have been studied, in the bulk phase, by CPMAS 13C NMR and VIS/UV spectroscopy and by DSC; complementary spectroscopic data on solutions of (2), including fluorescence studies, are also reported. Spectroscopic studies support the presence of an extended planar conjugated backbone in ‘as polymerised’ blue-black samples of (2), from which various forms of red-coloured polymer, with shorter conjugation lengths, can be obtained. Studies of the thermal behaviour indicate the existence of several differing thermal transitions for these materials and the results are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Optical and hydrodynamic properties of poly(biphenylsulfoneterephthalamide) (PPhSTPhA) (systematic IUPAC name: poly(iminoterephthaloylimino-2,2′-sulfonylbiphenyl-4,4′-diyl)) in sulfuric acid were investigated by means of flow birefringence and viscometry. Analysis of experimental molecular weight dependence on the shear optical coefficient made it possible to determine optical anisotropy of a monomer segment and a monomeric unit and the rigidity of the macromolecules. It was established that the molecules of this heterocyclic polyamide have the conformation of a kinetically rigid coil.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0192-253X
    Keywords: Signal transduction ; G-proteins ; adenylyl cyclase ; gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have cloned and characterized three genes (CAR1, CAR2, CAR3) encoding potential cell surface, cyclic adenosine 3′:5′ monophosphate (AMP) receptors from Dictyostelium discoideum. The three proteins are predicted to be substantially similar in amino acid sequence throughout most of their transmembrane (TM) and loop domains but are distinctly different in their carboxyl terminal segments. In addition, all three genes possess an intron which interrupts an equivalent codon of TM3.CAR1 is expressed early in development when the cAMP relay system is being established. As development proceeds multiple size forms of CAR1 RNA are detected which apparently result from differences in their 5′-untranslated regions. Late in development levels of CAR1 RNA decrease. In contrast, CAR2 encodes a single sized RNA which is expressed only during postaggregative development. CAR3 expression is ∼10% of CAR1 during early development, is maximal during tight aggregate formation but declines thereafter. Only one size class of CAR3 mRNA is detected throughout development.Because RNA for each of the three genes is present in postaggregative cells, it was of interest to determine the cell type distribution of each RNA. Gene-specific probes were hybridized to RNAs isolated from cells of Percoll gradient-enriched prespore and prestalk fractions and relative levels of hybridization compared. CAR1 and CAR3 show approximately the same pattern of accumulation; a 3-4 fold enrichment in prestalk cells. CAR2, however, is highly enriched in prestalk cells, more than 10 fold relative to prespore cells.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0192-253X
    Keywords: receptors ; transmembrane signalling ; Dictyostelium ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Using antibodies specific for the 3′, 5′-cyclic AMP (cAMP) cell surface receptor of Dictyostelium discoideum, we have screened γgtll expression libraries and isolated a series of cDNAs derived from cAMP receptor mRNA during early development. The identity of the cDNA clones was verified by multiple criteria: (1) β-galactosidase fusion proteins synthesized by isolated cDNA clones stain intensely with cAMP receptor directed antiserum, (2) these fusion proteins affinity purify antibodies specific for the cAMP receptor, (3) the cDNA probes hybridize to a 2 kb mRNA whose change in relative level of abundance during development parallels that of receptor mRNA as assayed by in vitro translation, (4) the 2 kb mRNA size equals that of receptor mRNA as determined by in vitro translation of size fractionated poly (A)+ RNA, and (5) RNA transcribed in vitro from cDNAs containing the entire protein-coding region produces a polypeptide by in vitro translation with an apparent molecular weight in close agreement with that of nascent cAMP receptor protein produced by in vitro translation of cellular RNA.The DNA sequence predicts an open reading frame of 392 amino acids. The deduced amino acid sequence contains seven domains enriched in hydrophobic residues. A model is proposed in which the cAMP cell-surface receptor traverses the lipid bilayer seven times in a pattern similar to that of other receptors, such as rhodopsin, which interact with G-proteins. The structural similarities suggest a gene family of related surface receptors from such evolutionarily diverse species as Dictyostelium, yeast, and mammals.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...