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  • 1
    Electronic Resource
    Electronic Resource
    Pilot scale production of a recombinant human epidermal growth factor, secreted by Bacillus brevis, using expanded bed adsorption (1998)
    Springer
    Journal of industrial microbiology and biotechnology 21 (1998), S. 208-214 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: human epidermal growth factor; Bacillus brevis recombinants; expanded bed adsorption; fermentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recombinant Bacillus brevis which carried an expression plasmid encoding the human epidermal growth factor (EGF) gene on a cryptic high-copy number plasmid, pHT926, extracellularly produced EGF in its biologically active form at a concentration of over 1.5 g L−1 in the culture broth in a 30-L jar fermenter. The culture broth also contained some other EGF compounds, which mainly consisted of oligomeric and polymeric forms with disulfide bonds. We developed a simple purification method for EGF, without prior cell removal from the culture broth, comprising cation exchange expanded bed adsorption followed by ultrafiltration with UF 10 000 and 3000 membranes. The EGF compounds were efficiently separated from the EGF in its native form in the expanded bed adsorption step. With this purification method, only EGF in its native form was recovered from the culture broth, with a yield of nearly 80%, and 90% purity. This efficient and economic system has made it possible to use EGF as a pharmaceutical in the livestock industry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900570
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  • 2
    Electronic Resource
    Electronic Resource
    Gene expression of Bacillus subtilis subtilisin E in Thermus thermophilus (1999)
    Springer
    Journal of industrial microbiology and biotechnology 23 (1999), S. 214-217 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: gene expression; subtilisin E; Thermus thermophilus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Bacillus subtilis subtilisin E gene was cloned into an expression vector of the extreme thermophile, Thermus thermophilus. Active subtilisin E was produced in E. coli, indicating that the Thermus promoter functions in E. coli. When the plasmid was further introduced into T. thermophilus, the subtilisin E gene was expressed and the gene product accumulated as an inactive pro-form, because the autoprocessing of the wild-type enzyme to the active-form did not occur at 50°C or above.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900722
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  • 3
    Electronic Resource
    Electronic Resource
    Isolation of freeze-tolerant laboratory strains of Saccharomyces cerevisiae from proline-analogue-resistant mutants (1997)
    Springer
    Applied microbiology and biotechnology 47 (1997), S. 405-411 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Since some amino acids, polyols and sugars in cells are thought to be osmoprotectants, we expected that several amino acids might also contribute to enhancing freeze tolerance in yeast cells. In fact, proline and charged amino acids such as glutamate, arginine and lysine showed a marked cryoprotective activity nearly equivalent to that of glycerol or trehalose, both known as major cryoprotectants for Saccharomyces cerevisiae. To investigate the cryoprotective effect of proline on the freezing stress of yeast, we isolated proline-analogue-resistant mutants derived from a proline-non-utilizing strain of S. cerevisiae. When cultured in liquid minimal medium, many mutants showed a prominent increase, two- to approximately tenfold, in cell viability compared to the parent after freezing in the medium at −20 °C for 1 week. Some of the freeze-tolerant mutants were found to accumulate a higher amount of proline, as well as of glutamate and arginine which are involved in proline metabolism. It was also observed that proline-non-utilizer and the freeze-tolerant mutants were able to grow against osmotic stress. These results suggest that the increased flux in the meta-bolic pathway of specific amino acids such as proline is effective for breeding novel freeze-tolerant yeasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050948
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanism of l-methionine overproduction by Escherichia coli: the replacement of Ser-54 by Asn in the MetJ protein causes the derepression of l-methionine biosynthetic enzymes (1999)
    Springer
    Applied microbiology and biotechnology 52 (1999), S. 179-185 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract We derived l-methionine-analogue-resistant mutants from Escherichia coli JM109 strain by mutagenesis with N-methyl-N′-nitro-N-nitrosoguanidine and selected the potent l-methionine-overproducing strains by microbioassay using lactic acid bacteria. One of the mutants, strain TN1, produced approximately 910 mg l-methionine/l following the addition of 0.1% yeast extract to fundamental medium containing glucose and ammonium sulfate. The l-methionine biosynthetic enzymes, cystathionine γ-synthase and cystathionine β-lyase, of the l-methionine-overproducing mutants were little repressed by l-methionine. To analyse the mechanism of l-methionine overproduction in the mutant strains, the metJ gene coding for the E. colimet repressor, MetJ protein, was cloned and sequenced by the polymerase chain reaction. The same single-amino-acid subsitution (wild-type Ser → Asn) at position 54 was observed in four independent l-methionine-producing mutants. When the wild-type metJ gene was then introduced into strain TN1 having the mutant metJ gene, the level of enzyme synthesis and the l-methionine productivity in the transformants were found to revert to those of the wild-type. It was therefore considered that only one point mutation in the metJ gene occurred in the l-methionine-producing mutants. These results demonstrate the important role of residue 54 of the MetJ protein in l-methionine overproduction, probably because of the derepression of l-methionine biosynthetic enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051506
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  • 5
    Electronic Resource
    Electronic Resource
    Cryopreservation of in vitro-grown shoot tips of taro (Colocasia esculenta (L.) Schott) by vitrification. 1. Investigation of basic conditions of the vitrification procedure (1997)
    Springer
    Plant cell reports 16 (1997), S. 594-599 
    Details
    ISSN: 1432-203X
    Keywords: Key words Shoot tips ; Cryopreservation ; Vitrification ; Taro [Colocasia esculenta (L.) Schott.] ; Tropical crops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro-grown shoot tips of taro (Colocasia esculenta (L.) Schott.) were successfully cryopreserved by vitrification. Excised shoot tips precultured on solidified MS supplemented with 0.3 M sucrose and maintained under a 16 h phtoperiod at 25°C for 16 h were loaded with a mixture of 2 M glycerol plus 0.4 M sucrose for 20 min at 25°C. The shoot tips were then sufficiently dehydrated with a highly concentrated vitrification solution (PVS2) for 20 min at 25°C prior to immersion into liquid nitrogen. Successfully vitrified and warmed shoot tips resumed growth within 7 days and developed shoots directly without intermediate callus formation. The average rate of shoot recovery amounted to around 80%, and the vitrification protocol appeared to be very promising for the cryopreservation of taro germplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050285
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  • 6
    Electronic Resource
    Electronic Resource
    Cryopreservation of invitro-grown shoot tips of taro (Colocasia esculenta (L.) Schott) by vitrification. 1. Investigation of basic conditions of the vitrification procedure (1997)
    Springer
    Plant cell reports 16 (1997), S. 594-599 
    Details
    ISSN: 1432-203X
    Keywords: Shoot tips ; Cryopreservation ; Vitrification ; Taro [Colocasia esculenta (L.) Schott.] ; Tropical crops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Invitro-grown shoot tips of taro (Colocasia esculenta (L.) Schott.) were successfully cryopreserved by vitrification. Excised shoot tips precultured on solidified MS supplemented with 0.3M sucrose and maintained under a 16 h phtoperiod at 25°C for 16 h were loaded with a mixture of 2M glycerol plus 0.4M sucrose for 20 min at 25°C. The shoot tips were then sufficiently dehydrated with a highly concentrated vitrification solution (PVS2) for 20 min at 25°C prior to immersion into liquid nitrogen. Successfully vitrified and warmed shoot tips resumed growth within 7 days and developed shoots directly without intermediate callus formation. The average rate of shoot recovery amounted to around 80%, and the vitrification protocol appeared to be very promising for the cryopreservation of taro germplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275498
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  • 7
    Electronic Resource
    Electronic Resource
    The Critical Role of the Cuo Chains in Metallizing the C-axis in YBa2Cu3O7−δ (1999)
    Springer
    Journal of low temperature physics 117 (1999), S. 1271-1275 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report measurements of the normal state c-axis magnetoresistance (MR) of untwinned single crystals of slightly overdoped YBa 2 Cu 3 O 7−δ . An orbital contribution to the transverse MR, a signature of coherent c- axis motion, arises only from the component of the magnetic field perpendicular to the CuO chains. This result implies that the CuO chains are primarily responsible for coherent transport along the c-axis in YBa 2 Cu 3 O 7−δ and that those regions of the CuO 2 planes that do not involve the chains remain two-dimensional, even in the absence of a normal state gap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022596306616
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  • 8
    Electronic Resource
    Electronic Resource
    Vortex Lattice Melting in YBa2Cu4O8 with H∥ab (1999)
    Springer
    Journal of superconductivity 12 (1999), S. 583-586 
    Details
    ISSN: 1572-9605
    Keywords: Flux lattice melting ; anisotropic superconductor ; c-axis resistivity ; YBa2Cu4O8
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We report c-axis resistivity measurements in the mixed state of YBa2Cu4O8 with the magnetic field applied parallel to the a-, b-, and c-axes. For all orientations of the magnetic field, a “kink” is observed in the resistive transition, associated with the first-order melting of an anisotropic three-dimensional vortex lattice. Whereas the melting lines for H∥b and H∥c obey the expected relation H m = H 0(1 − T/T c ) n with n = 1.5, H m (T) for H∥a follows a different temperature dependence with a lower exponent. This result is consistent with a suppression of the melting line due to a reduction in the dimensionality of YBa2Cu4O8 in this field geometry, as observed in normal-state magnetoresistance measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007708923730
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  • 9
    Electronic Resource
    Electronic Resource
    Search for magnetic order in undoped and doped spin‐gap systems by μSR (1997)
    Springer
    Hyperfine interactions 104 (1997), S. 37-42 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We introduce our μSR investigations of spin‐gap systems, such as, (1) a 2‐leg spin‐ladder material SrCu2O3, (2) a Haldane material (S=1 spin‐chain) Y2BaNiO5, (3) a spin‐Peierls material CuGeO3, (4) a spin‐chain# material Sr6Ca8Cu24O41. All of these antiferromagnetic spin systems are characterized by a spin‐gap between the singlet ground‐state and the triplet first excited states. In the above‐mentioned materials, we confirmed the absence of magnetic order down to milli‐Kelvin regime, supporting the non‐magnetic feature of the ground‐state. If a spin‐gap system is doped with charges and/or vacancies at the spin site, unpaired spins are induced out of the singlet ground‐state. In some materials, doping completely destroys the singlet ground‐state and induces a bulk magnetic order. We report μSR investigations of doped materials as well, which clarifies the existence/absence of a magnetic order upon doping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012686617527
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetics of the oxygen exchange reaction ofOrthopediodic acid in aqueous acidic solution at elevated pressures (1997)
    Springer
    Reaction kinetics and catalysis letters 62 (1997), S. 383-389 
    Details
    ISSN: 1588-2837
    Keywords: Orthoperiodic acid ; oxygen exchange ; activation volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Oxygen exchange reaction in H5IO6 was investigated by the NMR line-broadening method at elevated pressures. Kinetic parameters were obtained as kex 298=3.58×103 s−1, ΔH *=54.8±0.8 kJ mol−1, ΔS *=7±2 J mol−1K−1, and ΔV *=4.7±0.5 cm3 mol−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02475480
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