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  • 1
    ISSN: 1432-072X
    Keywords: cAMP ; Regulation ; Chlorophyll synthesis ; Chlorella fusca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The intracellular concentration of cAMP in the green alga Chlorella fusca was in the range of 2 · 10-9 to 10-8 moles/g dry weight and was strongly dependent on the growth conditions. The cAMP level was high with high light intensity, low nitrate or glucose concentration. Intracellular cAMP increased only by factor of 2 when high amounts (up to 10-3 M) of cAMP were added to the medium. Most of the given cAMP was converted to 5′-AMP. Addition of cAMP had little effect on the chlorophyll content of the cells, only at 10-6 M some enhancement in photoautotrophic cultures was observed. On the other hand high amounts of cAMP in the medium increased the growth rate. DBcAMP* showed a positive effect on chlorophyll synthesis and growth rate at much lower concentrations compared to cAMP. Stimulation effects of exogenous cAMP on the synthesis of chlorophyll were also observed in mixotrophic cultures with a high glucose/nitrate ratio, conditions where chlorophyll synthesis is repressed. Similar to autotrophic conditions DBcAMP was more effective than cAMP. These data indicate that cAMP may act in a system controlling the chlorophyll content of the cells in response to nutrients or light.
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  • 2
    ISSN: 1432-072X
    Keywords: Rhodospirillum rubrum ; Phosphatidylethanolamine ; Chromatophores ; Lipid distribution ; TNBA modification ; Membrane asymmetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution of phosphatidylethanolamine in the two lipid layers of chromatophores ofRhodospirillum rubrum has been analysed by chemical modification of phosphatidylethanolamine (PE) with trinitrobenzenesulfonic acid (TNBA) at low temperatures. Around 45±1% of the total phosphatidylethanolamine is labelled by this procedure independent on chromatophore purity, vesicle size, action of proteases and growth state of the cells. This demonstrates a complete modification of the accessible phosphatidylethanolamine and an asymmetric distribution of phosphatidylethanolamine, with 45% of the phosphatidylethanolamine in the outer part of the bilayer.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 57 (1967), S. 392-405 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In Gegenwart von ATP, Mn2ü (oder Mg2ü), CoA und Glutathion fixieren zellfreie Extrakte aus Sporophoren von Agaricus bisporus selbst in Abwesenheit exogener CO2-Acceptoren in erheblichem Maße Kohlendioxyd. Entsprechend der Hemmbarkeit dieser CO2-Fixierungsreaktionen durch Avidin und p-Chloromercuribenzoat handelt es sich bei diesen zum mindesten teilweise um durch Biotin-Enzyme katalysierte Vorgänge. Einer der endogenen CO2-Acceptoren ist sehr washrscheinlich mit aus Isovaleriansäure gebildetem β-Methylcrotonyl-CoA identisch. Die experimentellen Ergebnisse werden im Zusammenhang mit den bekannten physiologischen Effekten von CO2 auf Fruktifikation und Morphogenese des Kulturchampignons diskutiert. Es scheint, daß Biotin-abhängige Carboxylierungsreaktionen eine der biochemischen Grundlagen für den Kontrolleinfluß von Kohlendioxyd im Lebenscyclus von A. bisporus darstellen.
    Notes: Summary Cell-free extracts of sporophores of Agaricus bisporus incorporate considerable amounts of carbon dioxide into organic acids even without added substrate, provided that ATP, Mn2ü or Mg2ü, Coenzyme A and glutathione are present. These CO2-fixation reactions are inhibited by avidin and p-chloromercuribenzoate. It is therefore concluded that at least part of these reactions are katalyzed by biotin enzymes. One of the endogenous CO2-acceptors is probably identical with β-methylerotonyl-CoA, formed from isovaleric acid. The experimental results are diseussed in relation to the well-known physiological effects of carbon dioxide on fructification and morphogenesis in the cultivated mushroom. It is suggested that biotin-dependent carboxylations might represent the biochemical basis for the centrolling function of CO2 in the life cycle of A. bisporus.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 58 (1967), S. 339-356 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Aceton stimuliert die Inkorporation von H14CO3 - in organische Säuren durch zellfreie Extrakte von Agaricus bisporus. Als Endprodukte dieser CO2-Fixierung treten radioaktives Malat, Fumarat sowie Aspartat auf, und zwar unabhängig davon, ob H14CO3 - oder 1,3-14C-Aceton als Tracer verwendet wird. Beim eigentlichen Carboxylierungsprodukt handelt es sich sehr wahrscheinlich um Acetessigsäure. 2. Da die Inkorporation von 14CO2 im Acetonsystem die Gegenwart von ATP, Mg2+, CoA sowie GSH erfordert und durch Avidin und pCMB eine starke Hemmung erfährt, muß die Carboxylierung von Aceton zum mindesten indirekt von einem Biotinenzym abhängig sein. 3. Der Kulturchampignon enthält, wie hier erstmals gezeigt, eine Acetacetatdecarboxylase. Es werden mögliche Ursachen der beim Fruktifikationsbeginn auftretenden Ketogenese diskutiert.
    Notes: Summary 1. Acetone is shown to stimulate the incorporation of bicarbonate into organic acids by cell-free extracts of Agaricus bisporus. Radioactive malate, fumarate and aspartate were determined as end products of this CO2-fixation, regardless whether H14CO3 - or 1,3-14C-acetone was used as a tracer. Acetoacetate is an intermediate in the reaction sequence leading from acetone to these acids, an observation that indicates a carboxylation of the ketone. 2. The incorporation of HCO3 - mentioned above requires the presence of ATP, Mg2+, CoA and GSH; it is inhibited by avidin and pCMB. It is therefore suggested that the carboxylation of acetone depends on biotin, at least in an indirect manner. 3. The presence of acetoacetate decarboxylase in the common mushroom is shown and possible reasons for ketosis as occuring in the first phase of fruiting are discussed.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 54 (1966), S. 1-13 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary Cellfree extracts of Cl. butyricum catalyze the phosphoroclastic cleavage and the reversal of the reaction, the reductive carboxylation of acetylphosphate to pyruvate. Treatment of the extracts with DEAE-Cellulose removes the ferredoxin and the extract looses its catalytic activity. Adding back ferredoxin to DEAE-treated extracts restores the activity for synthesizing pyruvate up to 40%. Pyruvate serves as substrate for various reactions, which can be stimulated by DPN, Mn, and an amino donor.
    Notes: Zusammenfassung Zellfreier Extrakt von Clostridium butyricum kann die phosphoroclastische Reaktion und deren Umkehrung, die reduktive Carboxylierung von Acetylphosphat zu Brenztraubensäure, katalysieren. Durch die Behandlung an einer DEAE-Cellulosesäule wird das Ferredoxin vom Extrakt separiert; der Extrakt verliert dabei seine enzymatische Wirksamkeit. Durch Rekombination werden bis zu 40% der ursprünglichen Enzymaktivität wiederhergestellt. Aus dem gebildeten Pyruvat werden, besonders in Anwesenheit von Diphosphopyridinnucleotid, Glutamin und Mangan, weitere Verbindungen synthetisiert.
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  • 6
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Pyruvat kann durch belichtete Zellen von R. rubrum assimiliert und zur Synthese verschiedener Zellbestandteile verwendet werden. Ist das Angebot an Substrat und Lichtenergie groß genug, so wird ein Teil der Brenztraubensäure in Speicherstoffe eingebaut. Suspension der Zellen in Phosphat-puffer und Inkubation unter Wasserstoff stimuliert die Bildung des Speicherstoffes Poly-β-Hydroxybuttersäure. Die Synthese eines ebenfalls als Speicherstoff in R. rubrum bekannten Polysaccharids konnte vor allem bei großem Substratüberfluß und Inkubation unter Stickstoff beobachtet werden; es wurde jedoch auch unter optimalen Bedingungen nur ein geringer Anteil der total aufgenommenen Brenztraubensäure zur Synthese dieses Speicherpolysaccharids verwendet.
    Notes: Summary Illuminated cells of R. rubrum assimilate pyruvate and use it for the ynthesis of different cell components. A sufficient supply of substrate and light energy provided, part of the pyruvate is built into storage products. If the cells are suspended in phosphate buffer and kept under an atmosphere of molecular hydrogen the formation of the β-hydroxybutyrate polymer is stimulated. An excess of substrate and incubation under molecular nitrogen leads to the synthesis ofa polysaccharide, also known as storage product in R. rubrum; but even under optimal conditions only a small part of the pyruvate is used for the synthesis of this storage polysaccharide.
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  • 7
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary ATP was measured in samples of activated sludge under field conditions for several hours in a waste water treatment plant. The mean level of ATP in the sludge is relatively independent of the inflow of organic material, however a fast increase in the supply of organic material results in a simultaneous increase in the ATP. Since the inflow of the waste water treatment plant is continuously changing, oscillations in the ATP level are seen. It is concluded that average levels of ATP may give some information on the biological state of the activated sludge, while single determinations are not meaningful.
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  • 8
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary From enrichment cultures inoculated with water and sediments of a waste-water pond of a sugar refinery several photosynthetic nonsulphur bacteria have been isolated and tested for the ability to produce molecular hydrogen in the light. Strains have been found that utilize the freshly used, untreated waste substrate with higher yields than the laboratory strain used so far. Under the test conditions one strain showed higher hydrogen production rates from waste water than from any synthetic substrate.
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  • 9
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Autotrophic as well as heterotrophic bacteria and fungi play an important role for the industrial recovery of metals from low-grade ore or, in general, from low-grade mineral resources. The same inorganic bacterial pathways that are responsible for huge and expensive corrosion problems can be used for economical biohydrometallurgical applications. Metals and metalloids can be microbially transformed by oxidation, reduction, alkylation, dealkylation, solubilization, and␣precipitation mechanisms. Biohydrometallurgy, a branch of classical metallurgy, is not as widely publicized as other areas of metallurgy, e.g. pyrometallurgical or hydrometallurgical processes. Since 1990, approximately 15 international patent applications concerning biohydrometallurgical techniques have been claimed under the Patent Cooperation Treaty in contrast to a large number of patents concerning pyro- and hydrometallurgical techniques. Nevertheless, it is a very important field of investigation, especially for the future when aspects of a sustainable development have to be considered. New processes to support this development are applicable, at least on a laboratory scale. Bacterial leaching processes for the recovery of metals from solid residues are applied for low-grade ore, and, more recently, for fly ash, galvanic sludges, or, in general, for industrial wastes. It is possible to recover leached metals and to recycle them in metal-manufacturing industries. In addition, by removing the metals from residues, the environmental quality is improved, and the material can be re-used for construction purposes.
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  • 10
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary From enrichment cultures inoculated with water and sediments of a waste-water pond of a sugar refinery several photosynthetic nonsulphur bacteria have been isolated and tested for the ability to produce molecular hydrogen in the light. Strains have been found that utilize the freshly used, untreated waste substrate with higher yields than the laboratory strain used so far. Under the test conditions one strain showed higher hydrogen production rates from waste water than from any synthetic substrate.
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