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  • Life and Medical Sciences  (28)
  • Phanerochaete chrysosporium  (11)
  • Dopamine  (5)
  • Lignin model compounds  (5)
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  • 1
    ISSN: 1432-0983
    Schlagwort(e): Phanerochaete chrysosporium ; Transformation ; Heterologous expression ; Basidiomycetes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Protoplasted basidiospores of two different adenine auxotrophs of the lignin-degrading basidiomycete Phanerochaete chrysosporium were transformed to prototrophy using plasmids containing genes encoding adenine biosynthetic enzymes from Schizophyllum commune. Fragments containing these genes were subcloned into pUC18 and P. chrysosporium transformants obtained with these subclones were analyzed. The subclones were mapped for restriction sites and the approximate locations of the complementing genes were determined. One of these plasmids was used to transform the Neurospora crassa auxotrophic strain ade2, thereby identifying the S. commune ade5 biosynthetic gene as encoding phosphoribosylaminoimidazole synthetase.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0983
    Schlagwort(e): Phanerochaete chrysosporium ; DNA transformation ; Basidiomycete ; Adenine biosynthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A clone containing the Phanerochaete chrysosporium ade1 gene was isolated from a λEMBL3 genomic library using the ade5 gene encoding aminoimidazole ribonucleotide synthetase, from Schizophyllum commune, as a probe. A 6.0 kb fragment incorporating the ade1 gene was subcloned into pUC18 (pADE1) and used to transform the P. chrysosporium ade1 auxotrophic strain. Transformation frequencies were similar to those obtained previously with the S. commune ade5 gene; however, homologous transformants arose earlier than heterologous transformants. The transformants were mitotically and meiotically stable and Southern blot analysis indicated that the plasmid, pADE1, integrated ectopically in single or multiple copies. The pADE1 insert was mapped for restriction sites and the approximate location of the ade1 gene within the insert was determined.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-2072
    Schlagwort(e): Latent inhibition ; Dopamine ; Ondansetron ; 5HT3 antagonists ; Amphetamine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Latent inhibition (LI) is a behavioural phenomenon whereby preexposure to a stimulus without reinforcement interferes with the formation of subsequent associations to that stimulus. Using preexposure to a tone stimulus which subsequently serves as a conditioned stimulus for suppression of licking, we have confirmed that LI is disrupted by a low dose of amphetamine. Haloperidol was able to prevent this effect of amphetamine. Ondansetron, a selective and potent 5HT3 receptor antagonist, was also shown to be effective at blocking the amphetamine-induced disruption of LI at a dose of 0.01 mg/kg, but not at 0.1 mg/kg. In addition, it was demonstrated that ondansetron could enhance LI; using only ten preexposures, no LI was obtained in the saline group, but was apparent in animals given ondansetron, an effect which has been previously shown with haloperidol. Haloperidol, at the higher dose used, reduced suppression of licking, however, ondansetron at the effective dose had no such effect. It is concluded that ondansetron is able to attenuate increases in dopamine activity, produced pharmacologically with amphetamine without affecting baseline dopamine activity. The implications of these findings for a possible antipsychotic action of ondansetron are discussed.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-2072
    Schlagwort(e): Nicotine ; Latent inhibition ; Dopamine ; N. accumbens ; Haloperidol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Latent inhibition (LI) is a cognitive process whereby repeated exposure of a stimulus without consequence impedes the formation of subsequent associations with that stimulus. A number of studies in the rat have reported that LI is impaired by moderate systemic doses of amphetamine, an effect believed to be mediated via dopamine (DA) release in the nucleus accumbens. We and others have reported that nicotine has a selective effect in releasing DA in the accumbens rather than the caudate nucleus. We have therefore examined the ability of nicotine to disrupt LI, using a conditioned emotional response paradigm. Pre-exposure of a tone stimulus impaired subsequent conditioning between that stimulus and mild footshock, as indexed by suppression of licking by the tone subsequently presented alone. This LI effect was prevented, by an effect confined to the pre-exposed group, by doses of 0.4 or 0.6 mg/kg nicotine SC, which are accumbens selective, given before pre-exposure and before conditioning. The effect of nicotine in disrupting LI was prevented by prior administration of haloperidol at a dose (0.5 mg/kg) reported to reverse the disruptive effect of amphetamine on LI. Although the amphetamine effect requires two administrations, the effect of two administrations of nicotine was reproduced by a single dose of nicotine given before conditioning, but not by a single dose before pre-exposure. The results are discussed in relation to studies in human control and schizophrenic subjects, which suggest that increased DA activity in humans is also associated with impaired LI. The results indicate that nicotine does indeed increase functional DA activity in the rat accumbens; the consequent disruption of LI critically depends upon an action at the time of conditioning, and is independent of processes which occur during pre-exposure. In more general terms, this indicates the potential of drug experiments to complement behavioural studies on the mechanism of latent inhibition.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 63 (1979), S. 273-280 
    ISSN: 1432-2072
    Schlagwort(e): Dopamine ; Lateral inhibition ; Attention ; Schizophrenia ; Model for schizophrenia ; Schizophrenic symptoms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A hypothesis is briefly discussed proposing that schizophrenic symptoms are due to a breakdown in a mechanism by which conscious attention is limited and directed. It is shown that this mechanism can be modelled in terms of a simple nerve network in which every channel inhibits all the others. Failure of this inhibition would cause the defect hypothesised to occur in schizophrenia. It is shown that if dopamine is given a central role as transmitter in such a network then the various predictions about the biochemistry of schizophrenia that follow are not only consistent with the evidence for the ‘dopamine theory’ of schizophrenia, but also with much of the evidence held to be contrary to that theory. While not purporting to be an experimentally validated description of schizophrenia, this model goes beyond the single amine theories of schizophrenia and links dysfunctions in amine systems with specific behavioural control mechanisms. Given the current state of knowledge, such models can make only limited predictions about the biochemistry of schizophrenia. However, an attempt to link behavioural and biochemical systems in this way will be crucial for the development of viable animal models of schizophrenia.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-0983
    Schlagwort(e): Phanerochaete chrysosporium ; DNA transformation ; Basidiomycete ; Uracil auxotrophs ; Homothallism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Uracil auxotrophs of Phanerochaete chrysosporium were isolated using 5-fluoroorotate resistance as a selection scheme. The ura3 auxotrophs deficient in orotidylate decarboxylase and ura5 auxotrophs deficient in orotate phosphoribosyl transferase were characterized by enzyme assays and complementation tests. The ura5 auxotrophs were transformed to prototrophy with the ura5 gene from the ascomycete Podospora anserina. The ura3 auxotrophs were transformed to prototrophy with the ura3 gene from the basidiomycete Schizophyllum commune. The P. chrysosporium ura3 gene was isolated from a γEMBL3 genomic library using the S. commune ura3 gene as a probe. A 6.6-kb fragment incorporating the ura3 gene was subcloned into Bluescript SK+(pURA3.1) and used to transform P. chrysosporium ura3 auxotrophic strains. The pURA3.1 insert was mapped for restriction sites and the approximate location of the ura3 gene within the insert was determined. Double auxotrophic strains were transformed with either of two marker genes and the resulting single auxotrophic strains were crossed to demonstrate genetic recombination between two nuclei of identical genetic background.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 123 (1979), S. 319-321 
    ISSN: 1432-072X
    Schlagwort(e): Basidiomycete ; Vanillic acid ; Vanillate hydroxylase ; Monooxygenase ; Methoxy-p-hydroquinone ; Lignin biodegradation ; Phanerochaete chrysosporium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A soluble enzyme fraction from Phanerochaete chrysosporium catalyzed the oxidative decarboxylation of vanillic acid to methoxy-p-hydroquinone. The enzyme, partially purified by ammonium sulfate precipitation, required NADPH and molecular oxygen for activity. NADH was not effective. Optimal activity was displayed between pH 7.5–8.5. Neither EDTA, KCN, NaN3, nor o-phenanthroline (5 mM) were inhibitory. The enzyme was inducible with maximal activity displayed after incubation of previously grown cells with 0.1% vanillate for 30h.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 121 (1979), S. 37-41 
    ISSN: 1432-072X
    Schlagwort(e): Basidiomycete ; Basidiospores ; Fruit body ; Hymenium ; Catabolite repression ; Nitrogen repression ; cAMP ; Phanerochaete chrysosporium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In Phanerochaete chrysosporium fruit body formations is subject to strong catabolite repression by glucose in the presence of physiological levels of nitrogen. Walseth cellulose was found to be the best source of carbon for the induction of fruit body and consequent basidiospore synthesis. Ejected basidiospores collected from cultures grown under these conditions for two weeks are contaminated with neither conidia nor mycelial fragments and are therefore suitable for genetic analysis of recombination. Under conditions of nitrogen limitation, the glucose catabolite repression of fruit body synthesis was relieved. Exogenous adenosine 3′,5′-monophosphate but not other related nucleotides, also relieved glucose catabolite repression of fruit body formation.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1432-072X
    Schlagwort(e): Phanerochaete chrysosporium ; Lignin model compounds ; β-Aryl ether dimers ; Metabolism ; Methoxyhydroquinone ; Alkyl-phenyl cleavage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The white rot basidiomycete Phanerochaete chrysosporium metabolized guaiacylglycol-β-guaiacyl ether (I) in high nitrogen, shaking and stationary cultures. 2-(o-Methoxyphenoxy) ethanol (X), 2-(o-methoxyphenoxy) acetic acid (IX) and methoxy-phydroquinone (MHQ) were identified as products of the metabolism of (I). P. chrysosporium also metabolized guaiacylglycerol-β-guaiacyl ether (IV) in high nitrogen stationary cultures. 2-(o-Methoxyphenoxy)-1,3 propanediol (XII) and 3-hydroxy, 2-(o-methoxy-phenyxy) propionic acid (XIV) were identified as products of the metabolism of (IV). Finally, P. chrysosporium metabolized α-deoxyguaiacylglycol-β-guaiacyl ether (VI) and α-deoxyguaiacylglycerol-β-guaiacyl ether (VII) in limiting nitrogen cultures. 2-(o-Methoxyphenoxy) ethanol (X) and 2-(o-methoxyphenoxy)-1,3 propanediol (XII) were identified as products of the metabolism of VI and VII respectively indicating α hydroxylation of those substrates with subsequent alkyl-phenyl bond cleavage. Metabolites were identified after comparison with chemically synthesized standards by GLC-mass spectrometry.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1432-072X
    Schlagwort(e): Phanerochaete chrysosporium ; Lignin degradation ; Veratryl alcohol ; Secondary metabolism ; Mutants ; Phenol oxidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A pleiotropic mutant of Phanerochaete chrysosporium 104-2 lacking phenol oxidase and unable to form fruit bodies and a revertant strain 424-2 were isolated after UV mutagenesis. Strains 104-2 and 424-2 had no apparent dysfunction in primary metabolism with glucose as a carbon source. Unlike the wild type strain and strain 424-2, strain 104-2 was unable to evolve 14CO2 from 14C ring, side chain and 3-O-14C-methoxy labeled lignin. In addition, strain 104-2 was unable to evolve 14CO2 from a variety of lignin model compounds including 14C-4′-methoxy labeled veratrylglycerol-β-guaiacyl (V) ether, γ-14C-guaiacylglycerol-β-guaiacyl ether (VI), as well as 1-(14C-4′-methoxy, 3′-methoxyphenyl)1,2 propene (III) and 1-(14C-4′-methoxy-3′-methoxyphenyl) 1,2 dihydroxypropane (IV). The addition of peroxidase/H2O2 to cultures of strain 104-2 did not alter its capacity to degrade the labeled lignins. A variety of unlabeled lignin model compounds previously shown to be degraded by the wild type organism including β-aryl ether dimers and diaryl propane dimers were also not degraded by the mutant 104-2. The revertant strain 424-2 regained the capacity to degrade these compounds. The substrates described are degraded by oxygen requiring system(s) expressed during the secondary phase of growth, suggesting this pleiotropic mutant is possibly defective in the onset of postprimary metabolism. The inability of the mutant to produce the secondary metabolite veratryl alcohol and to elaborate enzymes in the veratryl alcohol biosynthetic pathway supports this hypothesis.
    Materialart: Digitale Medien
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