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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 21 (1949), S. 707-709 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biochemistry 50 (1981), S. 997-1024 
    ISSN: 0066-4154
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Biology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Advances in Biophysics 20 (1985), S. 109-135 
    ISSN: 0065-227X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Lake chubsuckers (Erimyzon sucetta) were exposed to coal ash–polluted sediments under conservative experimental conditions (filtered artificial soft water and abundant uncontaminated food). After 4 months of exposure, fish grazing the polluted sediments had significantly elevated body burdens of Se, Sr, and V. Selenium levels were particularly elevated, reaching mean whole body concentrations of 5.6 μg/g dry mass by the end of experimental manipulations. Twenty-five percent of fish exposed to pollutants died during the study. All surviving fish exposed to ash exhibited substantial decreases in growth and severe fin erosion. Total nonpolar lipids were two times higher in fish from the control treatment, but percent lipid did not differ between treatments. Because fish were presented with the same amount of food during the study, it appears fish exposed to ash utilized more energy for daily activities and/or were less efficient at converting available energy to tissues for growth and storage. The results were particularly interesting because we were unable to detect differences in standard metabolic rate (SMR) of fish between treatments. Increased energy expenditures not detectable in estimates of maintenance based on SMR, such as costs of digestion or activity, may have contributed to decreased energetic efficiency. Our findings corroborate previous studies which have documented the toxicity of ash-derived pollutants in fish.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 251 (1996), S. 591-598 
    ISSN: 1617-4623
    Keywords: Key words Escherichia coli ; ribA ; GTP cyclohydrolase II ; Oxidative stress ; soxRS regulon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We isolated a promoter that is inducible by paraquat, a superoxide-generating agent, from Escherichia coli using the promoter-probe plasmid pRS415. Sequence analysis revealed that the promoter derives from the ribA gene encoding GTP cyclohydrolase II, which is the first enzyme in the biosynthetic pathway of riboflavin. We fused the lacZ gene with the ribA promoter to monitor the expression of the gene in the single-copy state. LacZ expression from the ribA promoter was induced about eight-fold by 200 μM paraquat. Other known superoxide generators, menadione and plumbagin, also induced the expression of β-galactosidase in the fusion strain. On the other hand, no significant induction was observed following treatment with hydrogen peroxide, ethanol or heat shock. Induction of β-galactosidase was significantly reduced by the introduction of a Δsox-8 : : cat or soxS3 : : Tn10 mutation into the fusion strain, indicating that the ribA gene is a member of the soxRS regulon. The transcriptional start site was determined by primer extension analysis and putative binding sites for SoxS in both orientations were identified. GTP cyclohydrolase II activity in soluble extracts of E. coli increased more than three-fold on treatment with paraquat. This increase was dependent on the soxRS locus, and reflects the increase in transcript levels. However, flavin pools did not change significantly. A possible role for ribA induction during superoxide stress is discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 261 (1999), S. 374-380 
    ISSN: 1617-4623
    Keywords: Key wordsEscherichia coli ; ribA ; GTP cyclohydrolase II ; SoxS binding ; RNA polymerase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ribA gene, encoding GTP cyclohydrolase II in Escherichia coli, is a member of the soxRS regulon, which is induced by superoxide-generating agents. By evaluating lacZ expression driven by the ribA promoter carrying different lengths of upstream region in a monolysogen, we found that the superoxide-responsive element resides between 56 and 94 nucleotides upstream of the transcriptional start site. Purified SoxS protein bound to this region and protected nucleotides between positions −80 and −58 from degradation by DNase I. This region contains a putative SoxS-binding sequence (soxbox) in reverse orientation. The SoxS protein interacted specifically with four guanine residues within the soxbox sequence, as demonstrated by methylation interference analysis. These results clearly indicate that SoxS binds to the reversed soxbox sequence in the ribA gene, while in other known genes of the soxRS regulon it binds to the normally oriented soxbox. Possible modes of interaction between SoxS and RNA polymerase are discussed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 251 (1996), S. 591-598 
    ISSN: 1617-4623
    Keywords: Escherichia coli ; ribA ; GTP cyclohydrolase II ; Oxidative stress ; soxRS regulon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We isolated a promoter that is inducible by paraquat, a superoxide-generating agent, fromEscherichia coli using the promoter-probe plasmid pRS415. Sequence analysis revealed that the promoter derives from theribA gene encoding GTP cyclohydrolase II, which is the first enzyme in the biosynthetic pathway of riboflavin. We fused thelacZ gene with theribA promoter to monitor the expression of the gene in the single-copy state. LacZ expression from theribA promoter was induced about eight-fold by 200 µM paraquat. Other known superoxide generators, menadione and plumbagin, also induced the expression ofβ-galactosidase in the fusion strain. On the other hand, no significant induction was observed following treatment with hydrogen peroxide, ethanol or heat shock. Induction ofβ-galactosidase was significantly reduced by the introduction of a Δsox-8::cat orsoxS3::Tn10 mutation into the fusion strain, indicating that theribA gene is a member of thesoxRS regulon. The transcriptional start site was determined by primer extension analysis and putative binding sites for SoxS in both orientations were identified. GTP cyclohydrolase II activity in soluble extracts ofE. coli increased more than three-fold on treatment with paraquat. This increase was dependent on thesoxRS locus, and reflects the increase in transcript levels. However, flavin pools did not change significantly. A possible role forribA induction during superoxide stress is discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 96 (1934), S. 50-51 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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