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  • 1
    Electronic Resource
    Electronic Resource
    Biosynthesis and fate of compatible solutes in extremely halophilic phototrophic eubacteria (1990)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 75 (1990), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Most halophilic and halotolerant eubacteria are able to accumulate compatible solutes from their environment during salt stress. They are usually able to synthesize sugars and amino acids. These compatible solutes, however, are of less importance in extremely halophilic eubacteria, where usually glycinebetaine or ectoine is required. Extremely halophilic phototrophic sulfur bacteria of the genus Ectothiorhodospira are able to synthesize the three compatible solutes glycinebetaine, trehalose and ectoine. While glycinebetaine is the major compatible solute under all conditions the percentage of trehalose and ectoine varies depending on the availability of nitrogen sources. Using acetate plus bicarbonate as simultaneous substrates the three compatible solutes were analysed by 13C-NMR spectroscopy. The label found indicated the following biosynthesis pathways: glycine, derived from glyoxylate out of the Kornberg cycle, undergoes a three-fold methylation with S-adenosylmethionine as methyl donor. The latter is derived from the tetrahydrofolate pathway. Several enzymes of this pathway have been found and are under investigation. The labelling of trehalose indicates that the Calvin cycle is blocked in the presence of acetate. The two glucose moieties of trehalose are linked by trehalose-6-phosphate synthase. The enzyme was characterized. Ectoine is synthesized from aspartate via aspartophosphate, aspartate semialdehyde and α, β-diaminobutyrate. Dilution stress leads to rapid excretion of betaine and ectoine, followed by immediate uptake to balance overshoot excretion. Trehalose is not excreted under dilution stress but is degraded by trehalase and subsequently metabolized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb04098.x
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  • 2
    Electronic Resource
    Electronic Resource
    Degradation of the compatible solute trehalose in Ectothiorhodospira halochloris: isolation and characterization of trehalase (1990)
    Springer
    Archives of microbiology 153 (1990), S. 600-606 
    Details
    ISSN: 1432-072X
    Keywords: Ectothiorhodospira halochloris ; Osmoregulation ; Betaine ; Phototrophic bacteria ; Haloalkaliphilic bacteria ; Trehalase ; Trehalose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Trehalase, which hydrolyzes the disaccharide trehalose to α-d-glucose was isolated and partially purified (124-fold) from the phototrophic halo-alkaliphilic bacterium Ectothiorhodospira halochloris. The molecular mass was determined to be 480,000 and the isoelectric point pH 5.6. Temperature optimum was found to be 40°C and the pH-optimum 7.8–8.1. In spite of its high K m-value of 0.5 M, trehalase of E. halochloris was shown to be specific for trehalose. Trehalase is activated by phosphate which is, however, not involved in the reaction mechanism. The enzyme is activated by the compatible solute betaine and inhibited by salts. In the presence of betaine the K m-value is lowered from 0.5 M to 0.16 M; moreover, betaine partially protects enzymatic activity from salt inhibition. The findings indicate that betaine might regulate the trehalose level in the cells by affecting trehalase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245272
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The role of trehalose as a substitute for nitrogen-containing compatible solutes (Ectothiorhodospira halochloris) (1990)
    Springer
    Archives of microbiology 153 (1990), S. 607-613 
    Details
    ISSN: 1432-072X
    Keywords: Anaerobic phototrophic bacteria ; Halophilic eubacteria ; Osmoadaptation ; Betaine Ectoine ; Trehalose ; Compatible solutes ; Ectothiorhodospira halochloris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The halophilic phototrophic bacterium Ectothiorhodospira halochloris is able to synthesize both nitrogen-containing (betaine, ectoine) and nitrogen-free (trehalose) compatible solutes. In the absence of external ammonium and under nitrogen-limited growth conditions ectoine was metabolized and trehalose partly replaced betaine. The cytoplasmic trehalose concentration did not exceeded 0.5 mol/kg water (approx. 30% of total compatible solutes). A decreasing content of betaine in cells growing under nitrogen limitation is a result of decreased biosynthesis. Apparently, the betaine pool cannot be used as a nitrogen source, not even in a situation of total nitrogen depletion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245273
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Low price conspiracy: Trade regulation and the case of Japanese electronics (1990)
    Springer
    Atlantic economic journal 18 (1990), S. 59-67 
    Details
    ISSN: 1573-9678
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Conclusion The analysis of low price conspiracy suggests that even if it were legal, it requires very special and uncommon conditions. Such conditions were not present in the U.S. television industry, and the Supreme Court correctly concluded that the evidence did not support the existence of a low price conspiracy involving Japanese television manufacturers. The Court indicated that persuasive actual cost evidence must be presented to overcome economic logic that predation is very unlikely. Predation can still be shown but the standard of proof is high. After all allegations of low price conspiracy may be more likely to limit competition than any actual low price conspiracy itself.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02299020
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    Paper (German National Licenses)
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