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  • 1
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] By defining the somatic embryo developmental stage which expressed β-glucuronidase (GUS) at a high level yet was also competent to form embryogenic callus at a high frequency under selection, we obtained transformed Picea glauca (white spruce) embryogenic callus, embryos and seedlings ...
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  • 2
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Gibberellin-growth retardant interactions on the vegetative growth and flowering of the vine Clerodendrum thomsoniae Balf. were studied using both exogenous treatments and biologically testing the acid fraction attained from the plant extract. The growth retardant, ancymidol, greatly retarded stem elongation and markedly increased flowering under inductive environments. Gibberellin A3 (GA3) application to the shoot tip stimulated vine growth, prevented flowering under inductive environments, and completely overcame ancymidol-induced effects. In contrast to GA3, treatment with GA7 had little effect on vegetative growth but increased flowering under inductive environments. The elevated activity of gibberellin-like compounds, as determined by bioassay, were similar except for a marked increase in levels in ancymidol-treated plants grown under inductive environmental conditions. Microscopic examination of the stem tip indicated that the action of the growth regulators involved the induction of floral buds. Thus, in Clerodendrum, ancymidol appears to stimulate an unknown gibberellin(s) and simultaneously acts antagonistically with GA3.
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  • 3
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Protoplast donor tissues (leaves of shoots in culture) from a herbaceous plant (Solanum etuberosum) and two woody species (Populus alba × P. grandidentata cv. Crandon and Betula platyphylla szechuanica) were compared during plasmolysis in a range of osmotic agents and potentials. Cells from both Solanum and Populus, species proven to be amenable to protoplast division and regeneration, plasmolyzed readily at higher osmotic potentials than cells from Betula, a species recalcitrant to prolonged culture after protoplast isolation. Betula leaf mesophyll cells exhibited persistent membrane-to-wall attachments and many failed to plasmolyze even under extreme osmolarity. Although their leaves exhibited similar photosynthetic rates, photosynthetic capacity was lost from Betula protoplasts upon isolation, and retained by Solanum protoplasts. Differential stress after isolation was not detectable through vital staining, but only Solanum and Populus gave both high protoplast yields and high plating efficiencies in continued culture.
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  • 4
    ISSN: 1432-203X
    Keywords: Key words Solanum tuberosum L. ; In vitro tuberization ; Micropropagation ; Invertase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Potato microtubers are used as pathogen-tested in vitro stocks for certified seed potato production. Microtubers grown in a rotating bioreactor grew at a faster rate when the medium was replaced frequently. Although the total microtuber number was not affected, the number of microtubers over 1 g quadrupled when 75% of the medium was replaced every 2 weeks when compared with no medium refreshment. Significantly slower microtuber growth rates resulted when a lower sugar concentration (40 g 1−1 instead of 80 g 1−1) was used or when a mixture of glucose and fructose replaced sucrose. Although high sucrose levels are necessary for optimal microtuber production, the sucrose supplied was rapidly hydrolyzed into glucose and fructose, making the long-term maintenance of desirable sucrose levels difficult. These results indicate that successful strategies to reduce sucrose hydrolysis without inhibiting microtuber growth will improve the efficiency of sucrose utilization in potato microtuber bioreactors.
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  • 5
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three different target tissues (protoplast-derived cells, nodules, and stems) and two unrelated hybrid genotypes of Populus (P. alba x P. grandidentata ‘Crandon’ and P. nigra ‘Betulifolia’ x P. trichocarpa) have been stably transformed by electric discharge particle acceleration using a 18.7 kb plasmid containing NOS-NPT, CaMV 35S-GUS, and CaMV 35S-BT. Four transformed plants of one hybrid genotype, NC5339, containing all 3 genes were recovered and analyzed. Two expressed GUS and one was highly resistant to feeding by 2 lepidopteran pests (the forest tent caterpillar, Malacosoma disstria, and the gypsy moth, Lymantria dispar.) Pretreatment of the target tissues, fine-tuning of the bombardment parameters, and the use of a selection technique employing flooding of the target tissues were important for reliable recovery of transformed plants.
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  • 6
    ISSN: 1573-5028
    Keywords: conifer ; gene expression ; heterologous promoters ; inducible promoter activity ; particle acceleration ; transient assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electrical discharge particle acceleration was used to test the transient expression of numerous inducible angiosperm promoters in a gymnospermPicea glauca (white spruce). Promoter expression was assayed in three different tissues capable ofin vitro regeneration, zygotic embryos, seedlings and embryogenic callus. The promoters tested include the light-inducibleArabidopsis and soybean ribulose-1,5-bisphosphate small subunit promoters and a maize phosphoenolpyruvate carboxylase promoter; a soybean heat-shock-inducible promoter, a soybean auxin inducible promoter and a maize alcohol dehydrogenase promoter. Promoters were cloned into a promoter-less expression vector to form a promoter-β-glucuronidase-nopaline synthase 3′ fusion. A similar construct was made using the cauliflower mosaic virus 35S (CaMV 35S) promoter as a control. All promoters were expressed in white spruce embryos, yet at levels lower than CaMV 35S. In addition, in the embryos the heat-shock and the alcohol dehydrogenase promoters showed inducible expression when given the proper induction stimulus. In seedlings, expression of all promoters was lower than in the embryos and expression was only inducible with the heat-shock promoter in the cotyledons. Of the tissues tested, the expression level of all promoters was lowest in embryogenic callus. Interestingly, the expression of the β-glucuronidase gene in embryogenic callus was restricted to the proembryonal head cells regardless of the promoter used. These results clearly demonstrate the use of particle bombardment to test the transient expression of heterologous promoters in organized tissue and the expression of angiosperm promoters in a gymnosperm.
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  • 7
    ISSN: 1573-5044
    Keywords: conifer ; cytokinin ; organogenesis ; Picea glauca ; tissue culture ; white spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Picea glauca (white spruce) zygotic embryos and one-week-old-seedling epicotyl explants were placed on either Woody Plant Medium (WPM) or half-strength Schenk & Hildebrandt (1/2S&H) medium supplemented with varying levels of benzyladenine (BA) (0.1, 1.0, 10, 50, 100 μM), zeatin (10, 50, 100 μM) or thidiazuron (TDZ) (0.01, 0.1 μM). In addition to differences in the number of buds induced at three months on the two media, buds induced on WPM were visually more uniform, less vitrified and elongated faster. On 1/2S&H supplemented with BA, maximum bud induction from embryos occurred on 1.0 μM BA with 0.01 μM TDZ with higher BA concentrations inhibitory to bud induction. In contrast, on WPM there was little difference in the number of buds induced from embryos placed on 10, 50 and 100 μM BA with or without TDZ. One-week-old-seedling epicotyl explants required higher BA levels on 1/2S&H, as bud induction at three months was greatest at 10 μM BA. On WPM, as with the embryos, there were only minor differences in the number of buds induced from epicotyl explants on the various BA levels. Zeatin was more effective at inducing buds than BA with both media. From embryos, bud induction was greatest on 50 or 100 μM zeatin without TDZ and 50 or 100 μM zeatin with or without TDZ on 1/2S&H and WPM respectively. From epicotyl explants on 1/2S&H, there was little difference in the number of buds induced with the zeatin concentrations used, while with WPM, 50 and 100 μM zeatin induced the greatest number of buds. Interestingly, with BA, the epicotyl explants needed a higher level than the embryos for maximal response, while with zeatin, the level was the same for both embryos and epicotyl explants. Long-term (six month) survival was higher on WPM than with 1/2S&H. Additionally, embryos had a higher percentage of genotypes surviving at six-months when compared with epicotyl explants. For overall survival and development of the buds, 50 μM zeatin with 0.01 μM TDZ was the best treatment tested.
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