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  • 1
    Electronic Resource
    Electronic Resource
    Extension of Sp2/0 hybridoma cell viability through interleukin-6 supplementation (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 439-446 
    Details
    ISSN: 0006-3592
    Keywords: cell culture viability ; apoptosis ; IL-6 ; hybridomas ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sp2/0 hybridoma cells die principally by apoptosis in batch culture. We have found that cultures of the Sp2/0 hybridoma exhibit increased viability in response to interleukin 6 (IL-6) supplementation relative to control cultures during serum shiftdown experiments. When shifted from a medium containing 10% fetal bovine serum (FBS) to a medium with 1% FBS, IL-6 supplemented cultures displayed viabilities and viable cell densities similar to control cultures containing 10% FBS. The degree of the survival response induced varied in accordance with the severity of the shiftdown, as cells resuspended in a high serum medium showed little observable enhancement in viability. The extension in culture viability was not accompanied by an observable decrease in growth relative to control cultures, indicating that the effect was not a consequence of growth inhibition. These results suggest the existence of serum components with behavior functionally similar to IL-6, with respect to enhancing cell survival, and that under certain experimental conditions IL-6 serves as a survival factor. In contrast to the extended viability displayed by cultures supplemented with IL-6, Sp2/0 cultures transfected with IL-6 cDNA expression vectors displayed a growth inhibitory response relative to control cultures. This inhibitory response was characterized by an extended lag phase following inoculation, and a decrease in batch culture cell yield. The depression in cell yield varied with serum concentration, with the largest depression occurring at high serum concentrations. We conclude that interactions between components in serum, presumably growth factors, and cytokines play an important role in altering the behavior of industrially relevant cell lines in culture. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 439-446, 1997.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Growth factor and Bcl-2 mediated survival during abortive proliferation of hybridoma cell line (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 164-171 
    Details
    ISSN: 0006-3592
    Keywords: cell death ; apoptosis ; bcl -2 ; cell culture ; cell viability ; growth factors ; survival factors ; abortive proliferation ; hybridomas ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cultures of the CRL-1606 hybridoma (ATCC) have been reported to undergo continuous proliferation with simultaneous death during nutrient limited fed-batch fermentations. The bcl-2 proto-oncogene has been shown to prevent cell death under a variety of otherwise death inducing conditions. We were interested in elucidating the nature of the massive death observed in cultures of CRL-1606, specifically with respect to the possible environmental causes, and the ability of overexpressed human bcl-2 (hbcl-2) to mitigate cell death. Abortive proliferation, or continuous proliferation in the presence of continuous death, could be induced in serum free cultures of CRL-1606 through the withdrawal of insulin provided the culture was competent for cell proliferation. Culture competency for proliferation was found to be solely determined by the presence of cell culture nutrients. Abortive proliferation was defective in cultures transfected with hbcl-2 and the enhanced viability observed resulted from an increased viable cell population and at the expense of the nonviable cell population normally found in untransfected cultures. Abortive proliferation was also observed in serum containing cultures upon serum shiftdowns. Like the insulin-supplemented serum free culture system, hbcl-2 transfected cultures exhibited defects in the abortive proliferation process. These results suggest that the massive death observed during nutrient-limited fed-batch fermentation originate, in part, from growth or survival factor limitations. Hence, approaches to design cell culture media that account for the cell's proliferation requirements without accounting for the cell's survival requirements may represent a cell death sentence. Given the transformed nature of the hybridomas, we conclude that the abortive proliferation of CRL-1606 is a consequence of inappropriate cell cycle entry in a survival factor limited environment. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 164-171, 1998.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Studies of transcriptional state heterogeneity in sporulating cultures of bacillus subtilis (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 234-242 
    Details
    ISSN: 0006-3592
    Keywords: gene expression ; Bacillus subtilis ; transcriptional state heterogeneity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Using a flow cytometry-based technique for detecting p-galactosidase. lacZ fusions have been used to study the pattern of gene expression exhibited by stationary phase cultures of Bacillus subtilis that have initiated the developmental pathway of spore formation. We have found that within such cultures there exist two distinct cell types: one that has induced the developmental program of gene expression and one that has not. This heterogeneity among transcriptional states is shown to be established early during the stationary phase and plays a significant role in influencing later stationary phase events. Additionally, when this technique is used to study gene expression in mutants that display altered patterns of gene expression, we are able to conclude that the cellular apparatus responsible for sensing and transducing stationary phase developmental signals represents a bottleneck that controls the expression of certain early stationary phase genes. These findings provide a demonstration of the utility of single cell measurements of gene expression and indicate that unless culture heterogeneity is properly taken into account, standard measurements of gene expression may not provide information suitable for the analysis of events occurring at the cellular level. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260470215
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