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  • 1
    ISSN: 1432-072X
    Keywords: Key wordsHydrogenovibrio marinus ; Hydrogen-oxidizing bacterium ; Marine bacteria ; Obligate chemolithoautotroph ; Form I RuBisCO ; sequences ; 16S rRNA gene sequence ; Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two form ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) genes from the obligately autotrophic, marine hydrogen oxidizer Hydrogenovibrio marinus were sequenced. The deduced amino acid sequences of both RuBisCOs revealed that they are similar to those of sulfur oxidizers (Thiobacillus) and a purple sulfur bacterium (Chromatium vinosum). According to the 16S rRNA gene sequences, H. marinus is also affiliated with these microorganisms, members of Thiomicrospira being the closest relatives. Sequence similarities of the 16S rRNA genes and of the RuBisCO genes among these γ-Proteobacteria suggest a common autotrophic ancestry. An ancestor of purple sulfur bacteria might be a common root of H. marinus and related sulfur oxidizers.
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  • 2
    ISSN: 1420-9071
    Keywords: Key words. Macrophage; endothelial cell; atherosclerosis; lipoprotein metabolism; cholesterol; apoptosis; host defence; Alzheimer's disease.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. In this review, we summarize the structure and function of the scavenger receptor family of proteins including class A (type I and II macrophage scavenger receptors, MARCO), class B (CD36, scavenger receptor class BI), mucinlike (CD68/macrosialin, dSR-CI) and endothelial (LOX-1) receptors. Two motifs have been identified as ligand-binding domains a charged collagen structure of type I and II receptors, and an immunodominant domain of CD36. These structures can recognize a wide range of negatively charged macromolecules, including oxidized low-density lipoproteins, damaged or apoptotic cells, and pathogenic microorganisms. After binding, these ligands can be either internalized by endocytosis or phagocytosis, or remain at the cell surface and mediate adhesion or lipid transfer through caveolae. Under physiological conditions, scavenger receptors serve to scavenge or clean up cellular debris and other related materials, and they play a role in host defence. In pathological states, they mediate the recruitment, activation and transformation of macrophages and other cells which may be related to the development of atherosclerosis and to disorders caused by the accumulation of denatured materials, such as Alzheimer's disease.
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  A bacterium, Azotobacter chroococcum 4A1M, isolated from a soil sample, produced an alginate-decomposing enzyme in the culture broth. The enzyme was purified to an electrophoretically homogeneous state. The purified enzyme showed maximum activity at pH 6.0 and 60° C; it was stable up to 60° C at pH 6.0 and activated by Ca2+ and inhibited strongly by Hg2+. The molecular mass of the enzyme was estimated to be 23 kDa by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and 24 kDa by gel filtration. Therefore, the enzyme was considered to be monomeric. The NH2-terminal amino acid sequence was determined to be H2N-Ala-Ser-Ile-Ala-Ile-Thr-Asn-Pro-Gly-Phe. The enzyme reacted only on the polymannuronate block of alginic acid, and two main reaction products were obtained when short-chain polymannuronate was used as a substrate. The degrees of polymerization of the two products were three and two respectively.
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  • 4
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A bacterium, Azotobacter chroococcum 4A1M, isolated from a soil sample, produced an alginate-decomposing enzyme in the culture broth. The enzyme was purified to an electrophoretically homogeneous state. The purified enzyme showed maximum activity at pH 6.0 and 60°C;it was stable up to 60°C at pH 6.0 and activated by Ca2+ and inhibited strongly by Hg2+. The molecular mass of the enzyme was estimated to be 23 kDa by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and 24 kDa by gel filtration. Therefore, the enzyme was considered to be monomeric. The NH2-terminal amino acid sequence was determined to be H2N-Ala-Ser-Ile-Ala-Ile-Thr-Asn-Pro-Gly-Phe. The enzyme reacted only on the polymannuronate block of alginic acid, and two main reaction products were obtained when short-chain polymannuronate was used as a substrate. The degrees of polymerization of the two products were three and two respectively.
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  • 5
    ISSN: 1573-7357
    Keywords: 66.20.+d ; 67.50.Dg ; 67.50.Fi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the viscosity and the slip length are reported for both the normal liquid and superfluid3He within the slip approximation. We used the hollow torsional oscillator. For the normal liquid3He the slip length is shorter than the theoretical expectation and there is no anomaly near the superfluid transition, but the viscosity shows the anomalous deviation from the Fermi liquid behavior which is thought to be attributed to the superfluid fluctuation. For the superfluid3He, the temperature dependence of the slip length agrees with the theory qualitatively and the viscosity agrees well with the theory quantitatively as far as the slip approximation is valid.
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  • 6
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have measured the viscosity, η, and the slip length, ζ, of normal and superfluid 3 He using a torsional oscillator with a thick sample space. We coated the oscillating surface with 2.5 layers of 4 He film to study how the 4 He thin film changes the scattering mechanism of 3 He quasiparticles at the cell wall at 5 bar and 21 bar. In the normal phase, the temperature dependence of the viscosity was changed a little by the 4 He film at 21 bar but no change was observed at 5 bar. The slip length was enhanced by 4 He coating at 5 bar. This enhancement indicates the increase of specularity of 3 He quasiparticles scattering at the oscillating surface. On the other hand, a reduction of the slip length was observed at 21 bar. In the superfluid phase, the temperature dependence of ζ supports the existence of Andreev reflection even with 4 He film on the surface at 5 bar and 21 bar.
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  • 7
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have performedcwNMR experiments on superfluid 3 He confined to a parallel-plate geometry with a μm scale spacing for a wide pressure range. A static field was applied parallel or perpendicular to the plate surface. The spectra of two absorption signals, a main and a satellite, have been observed below the superfluid transition temperature in a parallel field. As the temperature decreased, the main signal decreased with shifts to higher frequencies, and the satellite grew with shifts to much higher frequencies. From the temperature dependence of these signals and the result in the perpendicular field, it is confirmed that the main signal and the satellite correspond to the A phase signal (ABM state) and the B phase signal (BW state), respectively. The temperature dependence of the two signals indicates that a phase transition from the A phase to the B phase occurs with decreasing temperature. By analyzing these signals, we determine A–B transition temperatures experimentaly. TheA–Btransition temperature normalized by the superfluid transition temperature is 0.95 at 20 bar, and decreased further to 0.70 at 0 bar for a thickness of 0.88 μm for pure 3 He. The values of TAB/TC were slightly elevated when covering the surface with 4.5 layers of 4 He film, which suggests that this transition is also influenced by the surface condition.
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  • 8
    ISSN: 1432-203X
    Keywords: Key words Arabidopsis HSP18.2 ; HSP promoter ; Heat shock ; GUS chimeric gene ; Nicotiana plumbaginifolia ; Organ-specific expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The expression of the Arabidopsis heat-shock protein (HSP) 18.2 promoter β-d-glucuronidase (GUS) chimera gene was studied in various organs of the transgenic Nicotiana plumbaginifolia during the recovery phase at normal temperatures (20–22  °C) following heat-shock (HS) treatment. The optimum HS temperature for GUS activity in the anthers, petals and capsules was 42  °C, but in immature seeds and the placentas of capsules it was 36  °C and 39  °C, respectively. No apparent GUS activity was observed in any organs except for dry seeds after HS at 45  °C, although the activity in dry seeds was apparent even after HS at 48  °C. After HS at 42  °C, GUS activity in the flower tissues was the highest before anthesis and declined thereafter.
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  • 9
    ISSN: 1432-203X
    Keywords: Key words Arabidopsis HSP18.2 ; Heat shock protein promoter ; β-Glucuronidase ; Nicotiana plumbaginifolia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The expression of the Arabidopsis heat shock protein (HSP) 18.2 promoter-β-d-glucuronidase (GUS) chimera gene was investigated in transgenic Nicotiana plumbaginifolia plants during the recovery phase at normal temperatures (20–22  °C) after a heat shock (HS) treatment. GUS activity increased during the recovery phase after HS at 42  °C for 2 h, and maximal GUS activity was observed after 12 h at normal temperatures, at levels 50–100 times higher than the activity immediately after HS. After HS at 44  °C, little GUS activity was observed during the first 20–24 h at normal temperatures, but the activity increased gradually thereafter, to reach a maximum at 40–50 h. After HS at 45  °C, no GUS activity was observed throughout the experimental period. RT-PCR analysis showed that GUS mRNA remained for 10 h after a 2-h HS at 42  °C and for 40 h after a 2-h HS at 44  °C. These findings demonstrate that brief HS treatment, especially at a sublethal temperature, induces a long-term accumulation of HSP-GUS mRNA during the recovery phase.
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  • 10
    ISSN: 1432-203X
    Keywords: Key wordsAtropa belladonna ; Transformed root cultures ; Scale-up ; Tropane alkaloids ; Modified stirred bioreactors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A scale up of transformed root cultures of Atropa belladonna from a 300-ml flask to a 30-l tank was accomplished without any reduction in alkaloid productivity. Cutting treatment of seed cultures showed no distinct effect on root growth, morphology, and alkaloid content in conical flasks during 1 month of culture. Randomly cut roots thus grown were further cultivated in 3-l and 30-l modified stirred bioreactors for a scale-up culture. After 1 month of culture, 1490 mg of tropane alkaloids was produced by a 30-l culture of A. belladonna transformed roots. These roots contained the same level of atropine (5.4 mg/ g dw) as the roots of this plant grown in the field for 12 months and still contained a considerable amount of other alkaloids including 1.6 mg/g dw of 6-β-hydroxyhyoscyamine, 0.9 mg/g dw of scopolamine, and 2.0 mg/g dw of littorine.
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