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  • 11
    Electronic Resource
    Electronic Resource
    Lokalisation der Peroxidase-Isoenzyme in Protoplasten und Zellwänden von Nicotiana tabacum L. (1975)
    Springer
    Planta 122 (1975), S. 259-268 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Upon disk-electrophoresis with guaiacol as a substrate the peroxidase-isoenzymes of Nicotiana tabacum (L.) were localized on the gels in two anodic and two cathodic groups. By preparation of protoplasts and isolation of cell walls it was possible to show that only cathodic enzymes are located in the protoplasts in measurable amounts, whereas all the isoenzymes, anodic and cathodic, can be found associated with cell walls. The different groups of isoenzymes are bound to the cell wall in different ways as evidenced by differences in their extration. It seems possible that different biological functions are associated with the different groups of isoenzymes. The isoenzyme patterns of different organs and tissues of tobacco show qualitative differences only in the anodic (i.e. wall located) isoenzymes. It is suggested that the ontogenetic change in peroxidase-patterns is direct evidence of biochemical differences in the cell walls of the different tissues and organs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385274
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  • 12
    Electronic Resource
    Electronic Resource
    Cytology of budding and cleavage in tobacco mesophyll protoplasts cultivated in saline medium (1978)
    Springer
    Planta 142 (1978), S. 11-21 
    Details
    ISSN: 1432-2048
    Keywords: Budding ; Cleavage ; Mesophyll ; Protoplasts ; Tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tobacco (Nicotiana tabacum L., cv. Maryland) mesophyll protoplasts cultivated in saline medium divide by bud formation, migration of one nucleus into the bud, and subsequent furrowing. This process was investigated light and electron microscopically. The cytoplasm of the growing bud is richer in dictyosomes, rough endoplasmic reticulum profiles, mitochondria, and small vacuoles than is the cytoplasm of the mother cell, but in early stages lacks plastids. Only patches of wall material are found; most of the cell surface appears naked. Oriented sections of the cleavage furrow do not reveal a contractile ring of microfilaments under the fixation conditions used. The furrow is flanked by numerous microtubules, and is rich in coated vesicles. Nuclear division appears normal, but the phragmoplast vesicles appear empty, and the phragmoplast seems to disintegrate again later. The nucleus migrating into the bud does not show any signs of associated contractile structures. The results demonstrate that, in principle, higher plant cells are capable of a mode of division usually said to be “yeast-like”. The events of karyokinesis and cell plate formation are not therefore obligatorily linked processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385114
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  • 13
    Electronic Resource
    Electronic Resource
    Budding and cleavage division of tobacco mesophyll protoplasts in relation to pseudo-wall and wall formation (1975)
    Springer
    Planta 125 (1975), S. 1-13 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two saline media, differing primarily in the presence or absence of NH4 + but also in the concentration of sucrose, were developed for culture of tobacco (Nicotiana tabacum L.) mesophyll protoplasts. In the R0.6 medium, which does not contain NH4 + and only 1 g/l sucrose, protoplasts divide 2–3 times by budding and form only a pseudo-wall, i.e. a nonrigid structure containing polysaccharides. Later the cells degenerate, and sustained division does not take place. In the W 0.6 medium, which contains NH4 + and 30 g/l sucrose, the protoplasts form a rigid wall and divide by cleavage of the cells. After a few divisions, the walls of practically all of the newly formed cells degenerate into pseudo-walls, and the divisions cease. Only a few cells keep a wall, continue to divide, and form colonies. A very high frequency of colony formations from protoplasts is obtained by culturing protoplasts for a week in R0.6 or W 0.6 and then diluting the culture with a sugar medium. A detailled study of the inorganic and organic components of the saline media showed a strong interaction between the nitrogen supply and the cytokinin requirement. The advantages of the saline media in obtaining cell colonies from protoplasts, the problems associated with budding-type division, the causes of the cessation of division when no complete wall is formed, and the conditions necessary for wall formation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388868
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  • 14
    Electronic Resource
    Electronic Resource
    Importance of the wall for cell division and in the activity of the cytoplasm in cultured tobacco protoplasts (1975)
    Springer
    Planta 123 (1975), S. 33-40 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When tobacco (Nicotiana tabacum L.) mesophyll protoplasts are cultivated in a medium in which osmotic pressure is maintained by using salts instead of sugars they divide 2–3 times although they never form a rigid wall which could be separated from the cytoplasm by the use of plasmolysis. Only a non-rigid pseudo-wall is present during division, showing that a rigid wall is not required for cell division. Diluting the salt medium with 5 volumes of sugar medium leads to the formation of a rigid wall as well as the initiation of sustained divisions. It is proposed that the complete wall is the place of synthesis of the substance(s) necessary for the division activity of the cytoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388058
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  • 15
    Electronic Resource
    Electronic Resource
    Time course of hormonal control of the first mitosis in tobacco mesophyll protoplasts cultivated in vitro (1979)
    Springer
    Planta 147 (1979), S. 181-185 
    Details
    ISSN: 1432-2048
    Keywords: Mitosis ; Nicotiana ; Phytohormones ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The presence of auxin and cytokinin is necessary for the induction of mitosis in tobacco mesophyll protoplasts cultivated in vitro. In their absence, protoplasts firstly accumulate inhibitors of mitosis in the culture medium, possibly because of non-coordinated cell-wall synthesis, and secondly evolve a nonmitotic and degenerative metabolism. By changing the intoxified medium, it is possible to show that auxin is necessary from the beginning of culture, while cytokinin is only required later to allow a step in the development of the mitotic apparatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388735
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  • 16
    Electronic Resource
    Electronic Resource
    Wavelets, generalized white noise and fractional integration: The synthesis of fractional Brownian motion (1999)
    Springer
    The journal of Fourier analysis and applications 5 (1999), S. 465-494 
    Details
    ISSN: 1531-5851
    Keywords: Fractional ARIMA ; midpoint displacement technique ; fractional Gaussian noise ; fractional derivative ; generalized functions ; self-similarity ; Primary 60G18 ; secondary 41A58 ; 60F15.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We provide an almost sure convergent expansion of fractional Brownian motion in wavelets which decorrelates the high frequencies. Our approach generalizes Lévy's midpoint displacement technique which is used to generate Brownian motion. The low-frequency terms in the expansion involve an independent fractional Brownian motion evaluated at discrete times or, alternatively, partial sums of a stationary fractional ARIMA time series. The wavelets fill in the gaps and provide the necessary high frequency corrections. We also obtain a way of constructing an arbitrary number of non-Gaussian continuous time processes whose second order properties are the same as those of fractional Brownian motion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01261639
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  • 17
    Electronic Resource
    Electronic Resource
    Characterization of a germin-like protein gene expressed in somatic and zygotic embryos of pine (Pinus caribaea Morelet) (1998)
    Springer
    Plant molecular biology 38 (1998), S. 1179-1190 
    Details
    ISSN: 1573-5028
    Keywords: apoplast ; cDNA cloning ; conifer embryogenesis ; gene expression ; germin-like proteins ; Pinus caribaea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Germin-like proteins (GLPs) ionically bound to the walls of preglobular somatic embryos of Pinus caribaea Morelet are markers of this early developmental stage. In order to reveal the physiological implications of such markers during early embryo development, we isolated a cDNA clone from somatic embryos predicted to encode a protein with sequence similarity to GLPs. PcGER1 has an open reading frame corresponding to a 220 amino acid polypeptide with a putative N-glycosylation site on Asn-69. The presence of a 24 amino acid putative signal peptide supports the hypothesis of an apoplastic location. The N-terminal 20 amino acid sequence of the predicted mature protein is identical to the amino terminal sequence of GP111, one of the extracellular pine GLPs previously identified. Southern blot hybridizations indicate that PcGER1 is probably unique in the pine genome. Transcripts homologous to PcGER1 are abundant in all embryogenic lines, absent from nonembryogenic lines, and present in quiescent zygotic embryos but not in the female gametophyte, the haploid storage tissue of conifers. Their abundance sharply decreases during germination. Isolation of gf-0.8, a genomic fragment identical to PcGER1 cDNA sequence, confirms that no introns disrupt the coding region as it has been already described for wheat gf-2.8 and gf-3.8 genomic clones. Recombinant PcGER1, produced in Escherichia coli, is recognized by antibodies raised against the GP111 N-terminal nonapeptide and the unglycosylated wheat germin monomer. The implications of GLPs in pine embryogenesis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006033622928
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  • 18
    Electronic Resource
    Electronic Resource
    mRNAs newly synthesized by tobacco mesophyll protoplasts are wound-inducible (1990)
    Springer
    Plant molecular biology 15 (1990), S. 485-496 
    Details
    ISSN: 1573-5028
    Keywords: protoplasts ; P.R. proteins ; tobacco ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used 2-dimensional (2D) non-equilibrium pH gradient gel electrophoresis (NEPHGE) of in vitro synthesized proteins and northern hybridization with labelled cDNAs coding for three pathogenesis related (P.R.) proteins, to analyze the shift in mRNA content induced by the isolation and culture of tobacco mesophyll protoplasts. The in vitro protein pattern of mRNAs from freshly isolated protoplasts is characterized by the absence of most leaf spots and the appearance of 19 new spots. After 6 hours of culture, the mRNAs coding for the P.R. proteins become detectable and after 12 hours the protoplasts contain an mRNA population almost typical of callus cells. The different steps involved in the isolation and culture of protoplasts were analysed. Cutting off the leaf and sterilization do not change the mRNA set. In contrast, the mechanical injury applied to the leaf in order to facilitate the penetration of the enzymatic mixture induces a modification of the mRNA content identical to that resulting from protoplast isolation. Wounding is the essential event inducing dedifferentiation. Varying the culture medium and conditions leads to only limited modifications of the mRNA pattern. These results are discussed on the basis of present knowledge of the reaction of the plant to wounding and we suggest that wound healing callus and in vitro callus correspond to the same differentiation state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019165
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  • 19
    Electronic Resource
    Electronic Resource
    Nucleotide sequence of a cDNA encoding a tobacco thioredoxin (1991)
    Springer
    Plant molecular biology 17 (1991), S. 143-147 
    Details
    ISSN: 1573-5028
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00036817
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  • 20
    Electronic Resource
    Electronic Resource
    Analysis of DNA of male and femaleSphaerocarpos donnellii Aust. (Liverwort) (1973)
    Springer
    Molecular genetics and genomics 124 (1973), S. 167-176 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The karyotypes of females and males ofSphaerocarpos donnellii differ in that there is a large essentially heterochromatic X chromosome in the female (approx. 25 volume-% of the autosomes) and a small Y chromosome in the male (0.1–3 volume-% of the autosomes). DNA from females and males differ in buoyant densities in cesium chloride equilibrium gradients (1.7025 and 1.7035g cm-3, respectively) and in melting points (87.5 and 88.5°C in SSC). The differences are statistically significant. Base analyses revealed 2.5 Mol-% of the rare base 5-methyl cytosine. Upon reassociationSphaerocarpos DNA behaves kinetically in a heterogeneous manner. About 22% of the DNA is repetitive with an average kinetic complexity of 1.6×108 daltons. The kinetic complexity of the slow reassociating DNA fraction, considered to be of the single copy type, is 3.2×1010 daltons. No difference in the renaturation behavior between DNA of males and females could be detected with the techniques used. Our data thus indicate that X chromosomal DNA cannot contain large amounts of highly repeated nucleotide sequences and that it is slightly enriched in AT content compared to the autosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00265149
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