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  • 1
    Electronic Resource
    Electronic Resource
    New Routes to Plant Secondary Products (1987)
    [s.l.] : Nature Publishing Company
    Nature biotechnology 5 (1987), S. 800-804 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] For some years, there has been great interest in the exploitation of plant cell cultures to produce fine chemicals. With a few exceptions, progress in commercialization has been slow, largely due to the low and/or unstable productivity of many undifferentiated cultures. Recent developments leading ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nbt0887-800
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  • 2
    Electronic Resource
    Electronic Resource
    The stimulation of anthraquinone production by Cinchona ledgeriana cultures with polymeric adsorbents (1986)
    Springer
    Applied microbiology and biotechnology 24 (1986), S. 35-41 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Anthraquinones produced by suspension cultures of Cinchona ledgeriana are released into the medium, which becomes saturated with products late in the growth cycle. When a high affinity polymeric adsorbent, such as the macro-reticular Amberlite XAD-7, is added to the culture the concentration of anthraquinone in the medium is maintained at a low level and production may be stimulated 15-fold, yielding up to 20 mg/1/day. More than 90% of the product is released from the cells. For maximal yields it is shown that both the amount of adsorbent used and the time after sub-culture at which it is added to the system are critical. The value of such a method for product recovery from immobilised cells is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266282
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  • 3
    Electronic Resource
    Electronic Resource
    Purification and properties of putrescine N-methyltransferase from transformed roots of Datura stramonium L. (1994)
    Springer
    Planta 193 (1994), S. 9-15 
    Details
    ISSN: 1432-2048
    Keywords: Datura ; Cadaverine ; Putrescine-N-methyltransferase ; Root culture (Agrobacterium-transformed) ; Tropane alkaloid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Putrescine-N-methyltransferase (PMT; EC 2.1.1.53), the first enzyme in the biosynthetic pathway leading from putrescine to tropane and pyrrolidine alkaloids, has been purified about 700-fold from root cultures of Datura stramonium established following genetic transformation with Agrabacterium rhizogenes. The native enzyme had a molecular weight estimated by gel-permeation chromatography on Superose-6 of 40 kDa; sodium dodecyl sulphate-polyacrylamide gel electrophoresis of the peak fractions from Superose-6 chromatography revealed a band of 36 kDa molecular weight. Kinetic studies of the purified enzyme gave K m values for putrescine and S-adenosyl-l-methionine of 0.31 mM and 0.10 mM, respectively, and K i values for S-adenosyl-l-homocysteine and N-methylputrescine of 0.01 mM and 0.15 mM, respectively. The enzyme was active with some derivatives and analogous of putrescine, including 1,4-diamino-2-hydroxybutane and 1,4-diamino-trans-but-2-ene. Little activity was observed with 1,4-diamino-cis-but-2-ene and none with 1,3-diaminopropane or 1,5-diaminopentane (cadaverine), indicating a requirement for substrate activity of two amino groups in a trans conformation, separated by four carbon atoms. A large number of monoamines were inhibitors of the enzyme. Though not a substrate, cadaverine was a competitive inhibitor of the enzyme, with a K i of 0.04 mM; the significance of this in relation to the biosynthesis of cadaverine-derived alkaloids is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191600
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  • 4
    Electronic Resource
    Electronic Resource
    Abiotic factors elicit sesquiterpenoid phytoalexin production but not alkaloid production in transformed root cultures of Datura stramonium (1991)
    Springer
    Plant cell reports 10 (1991), S. 111-114 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The treatment of root cultures of Datura stramonium with copper and cadmium salts at external concentrations of approximately 1mM has been found to induce the rapid accumulation of high levels of sesquiterpenoid defensive compounds, notably lubimin and 3-hydroxylubimin. These compounds were undetectable in unelicited cultures. No net change was seen in the alkaloid content of the system following treatment with Cu2+ or Cd2+, the tropane alkaloid titre apparently being insensitive to elicitation. However, a considerable rapid and, in some instances, reversible release of alkaloid was observed. This resulted in the appearance of up to 50–75% of the total alkaloid in the medium after 40–60 h. Subsequently, in cultures treated with Cu2+ ions, though not in cultures treated with Cd2+ ions, this alkaloid was re-absorbed. These observations show how, in a single system, different groups of secondary products can show distinct differences in their responses to potential elicitors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232039
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  • 5
    Electronic Resource
    Electronic Resource
    Toxicity of quinoline alkaloids to cultured Cinchona ledgeriana cells (1987)
    Springer
    Plant cell reports 6 (1987), S. 118-121 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The toxicity of Cinchona alkaloids to cell cultures of C. ledgeriana has been studied in relation to alkaloid uptake and possibilities for selecting high-yielding cell lines. The most toxic, quinine, was completely toxic at 5.5 mM. Both quinine and quinidine were more toxic than their unmethoxylated precursors, cinchonidine and cinchonine. The permanently-charged metho-chlorides of quinine and cinchonidine were less toxic than the parent alkaloids, despite showing similar accumulation ratios in 5-day uptake experiments at sub-toxic concentrations (ca 1.7mM). The toxicity of the natural quinoline alkaloids appears to be a non-specific effect which may be caused by intracellular alkalinisation following uptake of the uncharged bases. The use of precursors of quinine and quinidine as toxic agents for the selection of cell lines with enhanced quinine and quinidine production is ruled out by the lower toxicity of these precursors and by the correlation of an apparently non-specific toxicity with uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276667
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  • 6
    Electronic Resource
    Electronic Resource
    Production of terpenes by differentiated shoot cultures of Mentha citrata transformed with Agrobacterium tumefaciens T37 (1990)
    Springer
    Plant cell reports 8 (1990), S. 601-604 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Crown gall initiation on Mentha × piperita var. citrata (Ehrh.) Briq. (mint) was investigated using a range of wild type and mutant strains of Agrobacterium tumefaciens. Axenic transformed shoot cultures of Mentha ‘citrata’ were established on plant stems inoculated with the nopaline strain T37 of Agrobacterium tumefaciens. The presence of T-DNA in the transformed tissues and the absence of bacterial contamination was established by Southern Blot hybridisation, using 32P labelled fragments of the T-DNA and virulence region of the Ti plasmid as probes. The shoot cultures synthesised a mint oil fraction which contained the major terpenes characteristic of the parent plant in quantities similar to those found in intact tissue. Oil glands were observed to be present on the leaves of the transformed culture using scanning electron microscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00270063
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  • 7
    Electronic Resource
    Electronic Resource
    Apparent free space and cell volume estimation: A non-destructive method for assessing the growth and membrane integrity/viability of immobilised plant cells (1984)
    Springer
    Plant cell reports 3 (1984), S. 161-164 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pre-existing methods for measuring cell or organelle volume based on the selective permeability of biological membranes have been modified to make them suitable for determining the intracellular volume of immoblised cells. When a freely permeable substance (e.g. tritiated water) and an impermeable substance (14C labelled mannitol is often suitable) are mixed with an immobilised cell culture, the two substances are diluted to different degrees. The extent of the difference allows the total intracellular volume of intact cells to be calculated. This volume is shown to be a useful parameter for assessing cell growth. The application of the method to follow membrane integrity and cell viability is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00270214
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  • 8
    Electronic Resource
    Electronic Resource
    Permeabilization of Cinchona ledgeriana cells by dimethylsulphoxide. effects on alkaloid release and long-term membrane integrity (1984)
    Springer
    Plant cell reports 3 (1984), S. 262-265 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dimethyl sulphoxide (DMSO) has been used to permeabilize cells of Cinchona ledgeriana in suspension culture and promote the release of intracellular alkaloids. 5–6% v/v is required before any release is seen, and greater than 20% DMSO is required for full release. Even at these high levels of DMSO release is slow, taking in excess of seven hours to reach completion. Conditions which produce significant release of alkaloids have a deleterious effect on cells. Many of the membranes permeabilized did not recover their ability to selectively exclude compounds such as mannitol when the DMSO was removed. It is concluded that DMSO is not a suitable material for inducing alkaloid release in any biotechnological exploitation of alkaloid production by C. ledgeriana.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00269308
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  • 9
    Electronic Resource
    Electronic Resource
    The use of the polymerase chain reaction in plant transformation studies (1991)
    Springer
    Plant cell reports 10 (1991), S. 221-224 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transformed root lines of Nicotiana species, containing NPTII and Gus genes, were used to study the parameters affecting the use of the Polymerase Chain Reaction as a routine analytical tool for quickly analysing plant transformants for the presence of a foreign gene. The basic reaction mix as described by Cetus Corporation (Saiki 1989) was close to optimal for successful PCR amplification of internal sequences of both NPTII and Gus from genomic plant DNA. The temperature of primer annealing in the PCR protocols was found to be the most important variable, as low temperatures caused amplification of artefact bands and smearing after analysis on ethidium bromide agarose gels. Various formulae for calculating the Tm for binding of primers of various lengths (20–30 bases) are described in relation to predicting suitable annealing temperatures in the PCR. For tobacco species the PCR reaction worked efficiently with up to 2 μg of genomic DNA. However, with DNA from Mentha species (mint), an inhibitor of the PCR process was co-extracted with the DNA which prevented amplification of target sequences, if more than 10 ng of genomic DNA was present in the reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232562
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  • 10
    Electronic Resource
    Electronic Resource
    Over-expressing a yeast ornithine decarboxylase gene in transgenic roots of Nicotiana rustica can lead to enhanced nicotine accumulation (1990)
    Springer
    Plant molecular biology 15 (1990), S. 27-38 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium rhizogenes-transformed root cultures ; Nicotiana rustica ; nicotine ; ornithine decarboxylase ; putrescine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transformed root cultures of Nicotiana rustica have been generated in which the gene from the yeast Saccharomyces cerevisiae coding for ornithine decarboxylase has been integrated. The gene, driven by the powerful CaMV35S promoter with an upstream duplicated enhancer sequence, shows constitutive expression throughout the growth cycle of some lines, as demonstrated by the analysis of mRNA and enzyme activity. The presence of the yeast gene and enhanced ornithine decarboxylase activity is associated with an enhanced capacity of cultures to accumulate both putrescine and the putrescine-derived alkaloid, nicotine. Even, however, with the very powerful promoter used in this work the magnitude of the changes seen is typically only in the order of 2-fold, suggesting that regulatory factors exist which limit the potential increase in metabolic flux caused by these manipulations. Nevertheless, it is demonstrated that flux through a pathway to a plant secondary product can be elevated by means of genetic manipulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017721
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