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  • Articles  (6)
  • amino acids  (6)
  • Springer  (6)
  • American Chemical Society
  • 1995-1999  (6)
  • 1996  (6)
  • Process Engineering, Biotechnology, Nutrition Technology  (6)
Collection
  • Articles  (6)
Publisher
  • Springer  (6)
  • American Chemical Society
Years
  • 1995-1999  (6)
Year
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cytotechnology 21 (1996), S. 81-89 
    ISSN: 1573-0778
    Keywords: apoptosis ; hybridoma ; amino acids ; starvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Two mouse hybridoma cell lines cultured in different basal media with the iron-rich protein-free supplement were subjected to deliberate starvation by inoculation into media diluted with saline to 50% or less. In the diluted media the growth was markedly suppressed and a large fraction of cells died by apoptosis. The cells could be rescued from apoptotic death by individual additions of amino acids, such as glycine, L-alanine, L-serine, L-threonine, L-proline, L-asparagine, L-glutamine, L-histidine, D-serine, β-alanine or taurine. Amino acids with hydrophobic or charged side chains were without effect. The apoptosis preventing activity manifested itself even in extremely diluted media, down to 10% of the standard medium. The activity of L-alanine in the protection of cells starving in 20% medium was shown also in semicontinuous culture. In the presence of 2 mM L-alanine the steady-state viable cell density more than doubled, with respect to control, and the apoptotic index dropped from 37% in the control to 16%. It was concluded that the apoptosis-preventing amino acids acted as signal molecules, rather than nutrients, and that the signal had a character of a survival factor. The specificity of present results, obtained with two different hybridomas, supports our view (Franěk and Chládková-Šrámková, 1995) that the membrane transport macromolecules themselves may play the role of the recognition elements in a signal transduction pathway controlling the survival of hybridoma cells.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 17 (1996), S. 47-52 
    ISSN: 1476-5535
    Keywords: amino acids ; aromatics ; E. coli ; DAHP ; PEP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Different approaches to increasing carbon commitment to aromatic amino acid biosynthesis were compared in isogenic strains ofEscherichia coli. In a strain having a wild-type PEP: glucose phosphotransferase (PTS) system, inactivation of the genes encoding pyruvate kinase (pykA andpykF) resulted in a 3.4-fold increase in carbon flow to aromatic biosynthesis. In a strain already having increased carbon flow to aromatics by virtue of overexpression of thetktA gene (encoding transketolase), thepykA and/orpykF mutations had no effect. A PTS glucose+ mutant showed a 1.6-fold increase in carbon flow to aromatics compared to the PTS+ control strain. In the PTS− glucose+ host background, overexpression oftktA caused a further 3.7-fold increase in carbon flow, while inactivation ofpykA andpykF caused a 5.8-fold increase. When all of the variables tested (PTS− glucose+,pykA, pykF, and overexpressedtktA) were combined in a single strain, a 19.9-fold increase in carbon commitment to aromatic biosynthesis was achieved.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 16 (1996), S. 374-376 
    ISSN: 1476-5535
    Keywords: soy ; hydrolysate ; nutrient ; fermentation ; ethanol ; amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An optimized soy-based medium was developed for ethanol production byEscherichia coli KO11. The medium consists of mineral salts, vitamins, crude enzymatic hydrolysate of soy and fermentable sugar. Ethanol produced after 24 h was used as an endpoint in bioassays to optimize hydrolysate preparation. Although longer fermentation times were required with soy medium than with LB medium, similar final ethanol concentrations were achieved (44–45 g ethanol L−1 from 100 g glucose L−1). The cost of materials for soy medium (excluding sugar) was estimated to be $0.003 L−1 broth, $0.006 L−1 ethanol.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cytotechnology 20 (1996), S. 33-41 
    ISSN: 1573-0778
    Keywords: insect cells ; metabolism ; energetics ; amino acids ; fluxes ; oxygen uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-0778
    Keywords: amino acids ; endothelium ; fermentation ; glycoconjugates ; microcarriers ; spinner cultivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Five types of dextran-based microcarriers (Dormacell™, Pfeifer and Langen) with different concentrations of dimeric DEAE anion-exchange groups (nitrogen contents from 1.2 up to 2.9%) were tested as growth substrates for the cultivation of human umbilical vein endothelial cells (HUVECs). All microcarriers were gelatinized before use to improve cell adhesion. The one with the highest DEAE-group density was found to be most suitable for HUVEC propagation reaching final cell densities of 8×105 viable cells ml-1 (95% viability) using microcarrier concentrations of 3 g l−1. Furthermore, metabolic data of glucose/lactate and amino acid metabolism are presented in this study. The concentrations of 18 amino acids were monitored throughout cultivation. A considerable decrease of glutamine and inverse increase of glutamate was observed. Cultivation with initial glucose concentration of 16.5 mmol l−1 resulted in high glutamine consumption rates, whereas high glucose-supplemented starting culture medium (30 mmol l-1) gave considerably lowered rates, indicating altered glutamine metabolism due to different glucose feeding. The glucose consumption and lactate production rates increased 2.6 fold and 3.5 fold, respectively, due to switch over from low to high glucose supplemented cultures. The rate of glucose metabolism was found not to be directly related to cell growth, because almost identical growth rates and doubling times were obtained. Considering the remaining 16 amino acids measured, serine concentrations considerably declined and glycine as well as alanine concentrations raised strongly. Most amino acid values were found insignificantly altered during 14 days of cultivation. Spinner vessel cultures served as inoculum for up scale propagation of HUVECs in membrane stirred 2 liter bioreactors. About 5×109 HUVECs were produced, which were used for the isolation and structural characterization of glycosphingolipids, cell membrane compounds, which are suggested to be involved in e.g. selectin-carbohydrate interaction (cell-cell adhesion), carcinogenesis and atherogenesis.
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  • 6
    ISSN: 1573-0778
    Keywords: lymphoblastoid cell line ; amino acids ; glucose ; lactate ; batch culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract This work presents data on the carbohydrate and amino acid metabolism of a lymphoblastoid cell line producing an IgG1 antibody. In static culture, it was observed that lactate levels were significantly lowered when the cells were cultured on galactose as a carbon source. The use of carbohydrate substitution may be useful in lowering lactate levels, if it is established that this component is toxic to the cells. In addition, carbohydrate substitution may be used to modify glycosylation patterns and hence pharmacokinetic properties of glycoproteins. The amino acids glutamine and tryptophan were shown to be limiting in batch culture on this medium (DR, a 1:1 mixture of DMEM and RPMI, with 4mM glutamine). Amino acids produced included alanine, proline and glutamate. Serine was consumed to exhaustion, which was followed by a depletion of extracellular glycine. Amino acid metabolism, specific antibody productivity and specific growth rate were shown to be functions of the inoculation density in stirred flask culture. The results have implications for the design of media for both low and high density antibody manufacture by these cell lines.
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