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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Langmuir 11 (1995), S. 375-376 
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Marine luminescent bacteria of the genera Vibrio and Photobacterium as well as Photorhabdus (Xenorhabdus) luminescens, an enterobacterium mutualistically associated with insect pathogenic soil nematodes, display different levels of salt tolerance when grown on nutrient broth medium (5% w/v NaCl for marine species and 3% w/v for Prb. luminescens). Osmolytes (compatible solutes) synthesized and/or accumulated for haloadaptation were identified using HPLC techniques and 13C-NMR spectroscopy. All species investigated in this study accumulated betaine and ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidine carboxylic acid) from the medium under elevated osmotic conditions. External supply of osmolytes improved both growth and salt tolerance. Only species belonging to the genus Vibrio were able to synthesize the compatible solute ectoine de novo. Glutamate also participated in osmoadaptation while trehalose was only found in V. fischeri species. In Prb. luminescens13C-NMR spectroscopy also revealed the presence of choline when grown on complex medium.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 12069-12071 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 165 (1998), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 161 (1998), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Using transposon mutagenesis we generated a salt-sensitive mutant of the halophilic eubacterium Halomonas elongata impaired in the biosynthesis of the compatible solute ectoine. HPLC determinations of the cytoplasmic solute content showed the accumulation of a biosynthetic precursor of ectoine, l-2,4-diaminobutyric acid. Ectoine and hydroxyectoine were not detectable. This mutant failed to grow in minimal medium with NaCl concentrations exceeding 4%. However, when supplemented with organic osmolytes, the ability to grow in high-salinity medium (15% and higher) was regained. We cloned and sequenced the regions flanking the transposon insertion in the H. elongata chromosome. Sequence comparisons with known proteins revealed significant similarity of the mutated gene to the l-2,4-diaminobutyric acid acetyltransferase from the ectoine biosynthetic pathway in Marinococcus halophilus. Analysis of a PCR product demonstrated that the ectoine biosynthetic genes (ectABC) follow the same order as in M. halophilus.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 128 (1995), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Molecular genetic studies of halophilic eubacteria have been limited by the lack of a suitable method for mutagenesis. To overcome this, we established a transposon mutagenesis procedure for the ectoine-producing, halophilic bacterium Halomonas elongata. We used suicide plasmids pSUP101 and pSUP102-Gm to introduce the transposons Tn5 and Tn7732 respectively into H. elongata via Escherichia coli SM10 mediated conjugation. Our finding that H. elongata is sensitive to aminoglycoside antibiotics at low salinity enabled us to apply transposons that mediate kanamycin resistance. The insertions of transposon In 1732 occurred at different sites in the chromosome of H. elongata, as proved by Southern hybridization analysis. Phenotypic analysis revealed that different auxotrophic and salt sensitive mutants were generated by mutagenesis with transposon Tn1732. To our knowledge this is the first report of a successful application of a transposon for direct generalized mutagenesis in a halophilic eubacterium.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1433-4909
    Keywords: Key wordsβ-Hydroxyectoine ; Betaine ; RNase A ; Differential scanning calorimetry ; Enzyme stabilization ; Osmolytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thermodynamic aspects of protein stabilization by two widespread naturally occurring osmolytes, β-hydroxyectoine and betaine, were studied using differential scanning calorimetry (DSC) and bovine ribonuclease A (RNase A) as a model protein. The osmolyte β-hydroxyectoine purified from Marinococcus was found to be a very efficient stabilizer. At a concentration of 3 M it increased the melting temperature of RNase A (T m ) by more than 12 K and gave rise to a stability increase of 10.6 kJ/mol at room temperature. The heat capacity difference between the folded and unfolded state (ΔC p ) was found to be significantly increased. Betaine stabilized RNase A only at concentrations less than 3 M. Also, here ΔC p was found to be increased. Calculation of the number of water molecules that additionally bind to unfolded RNase A resulted in surprisingly low numbers for both osmolytes. The significant stabilization of RNase A by β-hydroxyectoine makes this osmolyte an interesting stabilizer in biotechnological processes in which enzymes are applied in the presence of denaturants or at high temperature.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cancer chemotherapy and pharmacology 43 (1999), S. S78 
    ISSN: 1432-0843
    Keywords: Key words Thalidomide ; PSA ; LNCaP cells ; PC-3 cells ; cDNA array
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Thalidomide has been shown to have species- and metabolic-dependent antiangiogenic activity in vitro and in vivo, suggesting its potential in treating human angiogenesis-dependent pathologies such as solid tumors. Based on promising preclinical studies, thalidomide has entered phase II clinical trials for prostate, brain, breast cancer, and Kaposi's sarcoma. However, the antiangiogenic mechanism of action is largely unresolved, as are its effects on tumor-associated gene expression, cytokine secretion, etc. We have investigated the effects of thalidomide on: 1) the secretion of prostate-specific antigen (PSA) in a human androgen-dependent prostate cell line; 2) growth and viability of human prostate cells; and 3) differential gene expression profiles of thalidomide-treated vs untreated human prostate cells. A human androgen-dependent prostate carcinoma cell line (LNCaP) and a human androgen-independent prostate carcinoma cell line (PC-3) were incubated with thalidomide 0.6, 6, or 60 μg/mL for 5–6 days. Secreted PSA from LNCaP cells was measured using a commercial enzyme-linked immunosorbant assay. Cell viability studies were conducted in both LNCaP and PC-3 cells using the same thalidomide concentrations. Furthermore, the differential gene expression of thalidomide-treated LNCaP cells was compared to that of untreated control cells using a commercially available human cancer cDNA expression array system. Thalidomide-treated LNCaP cells demonstrated increased PSA/cell levels at all concentrations tested compared to untreated control cells. Thalidomide demonstrated a cytostatic effect in LNCaP cells but had no appreciable effect on PC-3 cell viability compared to untreated control cells. Comparison of cDNA expression arrays hybridized with thalidomide-treated LNCaP cDNA probes suggests that thalidomide may up- or downregulate expression of angiogenesis-related genes, i.e., vitronectin, but these differential effects require further verification. Thalidomide over a range of doses has demonstrated nontoxic, cytostatic activity in LNCaP cells and significant upregulation of LNCaP cell PSA secretion in vitro. Furthermore, preliminary data from cDNA nucleic acid arrays of thalidomide-treated LNCaP cells suggest that thalidomide upregulates a potential angiogenic modulatory protein, the vitronectin precursor, which may eventually link thalidomide's antiangiogenic activity with modulation of angiogenic vascular integrin pathways.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Fermilab experiment E735 located at the CO intersection region of the $$\sqrt s = 1.8$$ TeV $$p\bar p$$ collider analysed over 900 Φ→K + K − events. Measured were the transverse momentum spectrum, the correlation between the average transverse momentum 〈pt〉 and the charged particle multiphcityN c , as well as the probability of Φ production per charged track,N Φ /N c , versusN c . We have also made an estinate of the total inclusive cross section for Φ mesons, $$\sigma (p\bar p \to \phi X) = 7.3 \pm 2.2 mb$$ .
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 306-313 
    ISSN: 0006-3592
    Keywords: Halomonas elongata ; osmotic shock ; fed-batch ; compatible solutes ; ectoine ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel biotechnological process called “bacterial milking” has been established for the production of compatible solutes using the Gram-negative bacterium Halomonas elongata. Following a high-cell-density fermentation which provided biomass up to 48 g cell dry weight per liter, we applied alternating osmotic shocks in combination with crossflow filtration techniques to harvest the compatible solutes ectoine and hydroxyectoine. H. elongata, like other halophilic or halotolerant microorganisms, produces compatible solutes in response to the salinity of the medium. When transferred to a low salinity medium (osmotic downshock), H. elongata cells rapidly released their solutes to achieve osmotic equilibrium. Subsequent reincubation in a medium of higher salt concentration resulted in resynthesis of these compatible solutes and - after a defined regeneration time - the procedure could be repeated. By repeatedly performing this “bacterial milking” process (at least nine times) we were able to produce large amounts of ectoines with a biomass productivity of 155 mg of ectoine per cycle per gram cell dry weight. Further purification of the products was achieved by a simple two-step procedure based on cation exchange chromatography and crystallization. The principles described in this article may also be useful for the production of other low-molecular-weight compounds. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 306-313, 1998.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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