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  • 1
    ISSN: 1432-203X
    Keywords: Key words Peppermint ; Transformation ; Co-cultivation ; Coconut water ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Substantial improvement in peppermint (Mentha x piperita L. var. Black Mitcham) genetic transformation has been achieved so that the frequency of transgenic plants regenerated (percent of leaf explants that produced transformed plants) was 20-fold greater than with the original protocol. Essential modifications were made to conditions for Agrobacterium tumefaciens co-cultivation that enhanced infection, and for selection of transformed cells and propagules during regeneration. A systematic evaluation of co-cultivation parameters established that deletion of coconut water from the co-cultivation medium resulted in substantially increased transient β-Glucuronidase (GUS) activity, in both the frequency of explants expressing gusA and the number of GUS foci per explant (〉700 explants). Co-cultivation on a tobacco cell feeder layer also enhanced A. tumefaciens infection. Enhanced transformation efficiencies were further facilitated by increased selection pressure mediated by higher concentrations of kanamycin in the medium during shoot induction, regeneration, and rooting: from 20 to 50 mg/l in shoot induction/regeneration medium and from 15 to 30 mg/l in rooting medium. Raising the concentration of kanamycin in media substantially lowered the number of "escapes" without significant reduction in plant regeneration. These modifications to the protocol yielded an average transformation frequency of about 20% (〉2000 explants) based on expression of GUS activity or the tobacco antifungal protein, osmotin, in transgenic plants. Genetic transformation of peppermint has been enhanced to the extent that biotechnology is a viable alternative to plant breeding and clonal selection for improvement of this crop.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-203X
    Keywords: Key words Peppermint ; Transformation ; Agrobacterium ; GUS ; Transgenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The first transgenic peppermint (Mentha×piperita L. cultivar Black Mitcham) plants have been obtained by Agrobacterium-mediated transformation by cocultivation with morphogenically responsive leaf explants. Basal leaf explants with petioles, from leaves closest to the apex of in-vitro-culture-maintained shoots (5 cm), exhibited optimal shoot organogenetic responsiveness on medium supplemented with thidiazuron (8.4 µm). Shoot formation occurred at sites of excision on the leaf blade and petiole either directly from cells of the explant or via a primary callus. Analyses of transient GUS activity data indicated that DNA delivery by microprojectile bombardment was more effective than Agrobacterium infection. However, no transgenic plants were obtained from over 22,000 leaf explants after particle bombardment. Cocultivation of leaf explants with Agrobacterium strain EHA 105 and kanamycin selection produced transgenic plants. Greater transient and stable -glucuronidase (GUS) activities were detected in explants or propagules transformed with the construct where gusA was driven by the pBISN1 promoter rather than a CaMV 35S promoter. Eight plants were subsequently regenerated and verified as transgenic based on detection of the nptII transgene by PCR and Southern blot analyses. The Southern analyses indicated that the plants were derived from eight unique transformation events. All transgenic plants appeared morphologically normal. Analyses of GUS activities in leaves sampled from different portions of these transgenic plants, 10 months after transfer to the greenhouse, indicated that six out of the eight original regenerants were uniformly transformed, i.e., did not exhibit chimeric sectors.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 21 (1975), S. 176-177 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 31 (1985), S. 410-414 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Heat treatment of “shell” molybdena-alumina catalyst pellets results in macroscopic redistribution of the molybdena. Redistribution is minimal at 625°C but extensive at 750°C. After 6 hours at 750°, a sharp maximum is observed in the radial distribution. This is a result of opposing factors: radial diffusion inward from the initial shell, and preferential sintering of the alumina support in the shell region. Loss of molybdena by vaporization is not appreciable at 750°C but is serious at 875°C. A computer program has been developed to convert SEM-EDAX (scanning electron microscopy energy-dispersive analysis of x-ray) data for unpolished pellet section to a quantitative, smooth profile of Mo concentration as a function of reduced radial position.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 20 (1974), S. 515-522 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new analysis is presented for the extraction of Arrhenius parameters from experimental measurements of ignition temperatures during catalytic oxidation over electrically-heated metal wires. Butane oxidation on high purity platinum wires has yielded reproducible experimental results for the reaction rate and has provided consistent estimates of the Arrhenius parameters. First-order kinetics was assumed. The present treatment contains explicit consideration of: (1) the ohmic heating term; and (2) the end conduction heat loss from the catalytic wire. The effects of wire length, diameter, and configuration are reconciled when the ignition phenomenon is refferred to the center-point temperature of the wire.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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