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  • 1
    Electronic Resource
    Electronic Resource
    PSTV sequence similarity to large rRNA (1990)
    Springer
    Plant molecular biology 14 (1990), S. 625-627 
    Details
    ISSN: 1573-5028
    Keywords: viroid ; PSTV ; rRNA ; similarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027509
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Transgene expression variability (position effect) of CAT and GUS reporter genes driven by linked divergent T-DNA promoters (1991)
    Springer
    Plant molecular biology 17 (1991), S. 49-60 
    Details
    ISSN: 1573-5028
    Keywords: CAT ; GUS ; mas promoters ; position effect ; reporter genes ; transgene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forty-five individually transformed clonal tobacco callus lines were simultaneously assayed for both chloramphenicol acetyltransferase (CAT) and β-glucuronidase (GUS) activity resulting from expression of introduced reporter genes driven by the adjacent and divergent mannopine (mas) promoters. Excluding lines in which one or both of the enzyme activities was essentially zero, the activities of the reporter genes varied by as much as a factor of 136 (CAT) and 175 (GUS) between individual transformants. Superimposed upon the high degree of inter-clonal expression variability was an intra-clonal variability of 3–4-fold. The observed degree of intra-clonal reporter gene activity may be more extreme because of the regulatory characteristics of the mannopine promoters, but must still be addressed when considering the limitations of reporter gene-based analysis of transgene function and structure. There was no consistent correlation between the expression levels of the introduced CAT and GUS genes since the ratio of GUS to CAT activities (nmol min-1 mg-1) within individual lines varied from 0.05 to 49. Even divergent transcription from two directly adjacent promoter regions (both contained within a 479 bp TR-DNA fragment) is insufficient to guarantee concurrent expression of two linked transgenes. Our quantitative data were compared to published data of transgene expression variability to examine the overall distribution of expression levels in individual transformants. The resulting frequency distribution indicates that most transformants express introduced transgenes at relatively low levels, suggesting that a potentially large number ofAgrobacterium-mediated transformation events may result in silent transgenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00036805
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The expression of a chimeric soybean beta-tubulin gene in tobacco (1987)
    Springer
    Molecular genetics and genomics 209 (1987), S. 633-633 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331178
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The expression of a chimeric soybean beta-tubulin gene in tobacco (1987)
    Springer
    Molecular genetics and genomics 207 (1987), S. 328-334 
    Details
    ISSN: 1617-4623
    Keywords: Tubulin ; Cell transformation ; Gene expression ; Ti plasmid ; Agrobacterium tumefaciens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A chimeric tubulin gene has been constructed by the fusion of a genomic sequence containing a truncated soybean beta-tubulin gene with 2 kb of upstream DNA to the 3′ untranslated region containing the polyadenylation signal from transcription unit 7 of the octopine Ti plasmid pGV117. The chimeric gene has been incorporated into the Ti plasmid transformation vector pGV3850::pAP2034, along with a selectable marker gene active in plants (the neomycin phosphotransferase II gene, conferring kanamycin resistance). Strains of Agrobacterium tumefaciens haboring the plasmids were used to transform Nicotiana tabacum by the leaf disk method and plants were regenerated from transformed cells. Transgenic plants were self fertilized and the segregation of kanamycin resistance was assayed. DNA and RNA were extracted from transgenic plants, fractionated by agarose gel electrophoresis, blotted to nitrocellulose and hybridized to a probe specific for the chimeric gene to assess its structure and expression in transgenic plants. The chimeric gene was stably integrated into the tobacco genome without rearrangements and it was expressed as a polyadenylated RNA of 1.7 kb in the transformants. Genetic analysis revealed that the kanamycin-resistant phenotype was inherited in a Mendelian fashion over two generations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331597
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  • 5
    Electronic Resource
    Electronic Resource
    Bryophytes as experimental models for the study of environmental stress tolerance: Tortula ruralis and desiccation-tolerance in mosses (2000)
    Springer
    Plant ecology 151 (2000), S. 73-84 
    Details
    ISSN: 1573-5052
    Keywords: Bryophytes ; Desiccation ; Mosses ; Tortula ruralis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The development of a complete understanding of how plants interact with the environment at the cellular level is a crucial step in advancing our ability to unravel the complexities of plant ecology particularly with regard to the role that many of the less complex plants (i.e., algae, lichens, and bryophytes) play in plant communities and in establishing areas for colonization by their more complex brothers. One of the main barriers to the advancement of this area of plant biology has been the paucity of simple and appropriate experimental models that would enable the researcher to biochemically and genetically dissect the response of less complex plants to environmental stress. A number of bryophytes model systems have been developed and they have been powerful experimental tools for the elucidation of complex biological processes in plants. Recently there has been a resurgent interest in bryophytes as models systems due to the discovery and development of homologous recombination technologies in the moss Physcomitrella patens (Hedw.) Brach & Schimp. In this report we introduce the desiccation-tolerant moss Tortula ruralis (Hedw.) Gaert., Meyer, and Scherb, as a model for stress tolerance mechanisms that offers a great deal of promise for advancing our efforts to understand how plants respond to and survive the severest of stressful environments. T. ruralis, a species native to Northern and Western North America, has been the most intensely studied of all bryophytes with respect to its physiological, biochemical, and cellular responses, to the severest of water stresses, desiccation. It is our hope that the research conducted using this bryophyte will lay the foundationfor not only the ecology of bryophytes and other less complex plants but also for the role of desiccation-tolerance in the evolution of land plants and the determination of mechanisms by which plant cells can withstand environmental insults. We will focus the discussion on the research we and others have conducted in an effort to understand the ability of T. ruralis to withstand the complete loss of free water from the protoplasm of its cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026598724487
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Inhibition of tobacco NADH-hydroxypyruvate reductase by expression of a heterologous antisense RNA derived from a cucumber cDNA: Implications for the mechanism of action of antisense RNAs (1993)
    Springer
    Molecular genetics and genomics 239 (1993), S. 425-434 
    Details
    ISSN: 1617-4623
    Keywords: NADH-hydroxypyruvate reductase (HPR) ; Heterologous antisense RNA ; Antisense RNA inhibition ; Transgenic tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tobacco plants were genetically transformed to generate antisense RNA from a gene construct comprised of a full-length cucumber NADH-dependent hydroxypyruvate reductase (HPR) cDNA placed in reverse orientation between the cauliflower mosaic virus 35S promoter and a nopaline synthase termination/polyadenylation signal sequence. In vivo accumulation of antisense HPR RNA within eight independent transgenic tobacco plants resulted in reductions of up to 50% in both native HPR activity and protein accumulation relative to untransformed tobacco plants (mean transgenote HPR activity=67% wild type, mean transgenote HPR protein=63% wild type). However, in contrast to previous reports describing antisense RNA effects in plants, production of the heterologous HPR antisense RNA did not systematically reduce levels of native tobacco HPR mRNA (mean transgenote HPR mRNA level=135% wild type). Simple regression comparison of the steady-state levels of tobacco HPR mRNA to those of HPR antisense RNA showed a weak positive correlation (r value of 0.548, n=9 ; n is wild type control plus eight independent transformants; significant at 85% confidence level), supporting the conclusion that native mRNA levels were not reduced within antisense plants. Although all transgenic antisense plants examined displayed an apparent reduction in both tobacco HPR protein and enzyme activity, there is no clear correlation between HPR activity and the amount of either sense (r=0.267, n=9) or antisense RNA (r=0.175, n=9). This compares to a weak positive correlation between HPR mRNA levels and the amount of HPR activity observed in wild-type SRI tobacco plants (r=0.603, n=5). The results suggest that in vivo production of this heterologous HPR antisense RNA is inhibitory at the level of HPR-specific translation and produces its effect in a manner not dependent upon, nor resulting in, a reduction in steady-state native HPR mRNA levels. In this context, the observed antisense effect appears to differ mechanistically from most antisense systems described to date.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276941
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    Paper (German National Licenses)
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