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  • 1
    Electronic Resource
    Electronic Resource
    Motility in ungerminated grass pollen: association of myosin with polysaccharide-containing wall-precursor bodies (P-particles) (1997)
    Springer
    Sexual plant reproduction 10 (1997), S. 65-66 
    Details
    ISSN: 1432-2145
    Keywords: Key words Triticum aestivum ; Pollen vegetative cell ; Intracellular motility ; P-particles ; Myosin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Grass pollens lack a dormancy period, remaining in a partly hydrated state at maturation with the contents of the vegetative cell continuing in active motion thereafter. The polysaccharide-containing wall-precursor bodies, derived mainly from previous dictyosome activity (P-particles), move randomly throughout much of the vegetative cell, but at the apertural pole of the grain many follow tracks related to actin fibrils focused on the single aperture. Isolated P-particles are shown by immunofluorescence localization using an antimyosin antibody to be associated individually with myosin. This, together with the fact that movement in the vegetative cell is arrested reversibly by cytochalasins, indicates that their motility is actomyosin based.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050068
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  • 2
    Electronic Resource
    Electronic Resource
    The structure and prophylactic role of the angiosperm embryo sac and its associated tissues:Zea mays as a model (1999)
    Springer
    Protoplasma 209 (1999), S. 256-272 
    Details
    ISSN: 1615-6102
    Keywords: Embryo sac ; Viral infection ; Cuticle ; Zea mays ; Pollination ; Fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Various developmental phases can be distinguished in the definition of the archesporium and the early life of the embryo, takingZea mays (maize) as a model within the family Gramineae, and other families where pertinent: (1) the isolation of the megasporocyte and the functional spore derived from it; (2) the maturation of the specialized walls of the embryo sac, and their reinforcement by ensheathments derived from the contiguous nucellar cells during a sequence of phased genetic ablation; (3) the differentiation of the synergids, the associated flange, and the filiform apparatuses; (4) the blocking of the pollen tube pathway by secondary secretions in the micropylar region and the coagulation of the pollen tube cytoplasm within the filiform apparatuses during the process of fertilization; and finally (5) the development of a compound cutinized envelope of four fused layers (six where the outer integument is also involved) after fertilization. For the nascent haploid generation, the period of maximum vulnerability in respect to both pathogen invasion and the transition from diplophase control occurs during these phases. It is concluded that many of the protective features form a prophylactic shield and are key components of the angiosperms in general, which may have contributed to their evolutionary success as a group. Other physiological or biochemical adaptations or barriers may also supplement the mainly structural features described here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01453454
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  • 3
    Electronic Resource
    Electronic Resource
    Organelle movement and fibrillar elements of the cytoskeleton in the angiosperm pollen tube (1988)
    Springer
    Sexual plant reproduction 1 (1988), S. 16-24 
    Details
    ISSN: 1432-2145
    Keywords: Pollen tube ; Organelle movement ; Actin microfilament bundles ; Iris pseudacorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Continuous observation of organelles and other cytoplasmic inclusions in the older stretches of living pollen tubes of Iris pseudacorus shows that in the more attentuated parts of the protoplast they move along single, mainly longitudinally oriented fibrils, corresponding to those previously isolated from other species and shown to contain bundles of uniformly polarised actin microfilaments. The traffic associated with each fibril is unidirectional, but organelles move along them independently, sometimes with conspicuously different velocities. Larger columns of cytoplasm passing along the tube are associated with several such fibrils, as revealed in occasional discontinuities and also in columns isolated from the tube in suitable medium without fixation. The dimensions of the individual fibrils suggest that the bundles of actin microfilaments are not likely to be enclosed in a unit membrane corresponding to a tonoplast. If so, the nature of the continuous cavities traversed by numerous fibrils in the older parts of the pollen tube requires reappraisal, since these are more likely to be volumes of attentuated cytoplasm comparable with that of the central cavity of the sieve tube than vacuoles of the normal plant-cell type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227017
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  • 4
    Electronic Resource
    Electronic Resource
    Some permeability properties of angiosperm pollen grains, pollen tubes and generative cells (1988)
    Springer
    Sexual plant reproduction 1 (1988), S. 65-73 
    Details
    ISSN: 1432-2145
    Keywords: Helleborus foetidus ; Galanthus nivalis ; Pollen-grain and pollen-tube permeability ; Generative cell wall ; Generative cell permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The permeability of pollen grains, pollen tubes and generative cells of Helleborus foetidus and Galanthus nivalis has been investigated using four probes spanning a wide range of molecular weights: 4,6-diamidino-2-phenyl indole (DAPI; mol.wt. 350). Evans blue (mol.wt. 960), FITC-dextran (average mol.wt. 19400) and FITC-albumin (average mol.wt. 67000). DAPI penetrated into the vegetative cells of desiccated and hydrated pollen, and also entered growing pollen tubes. In contrast, the generative cells of hydrated pollen and of pollen tubes were highly resistant to penetration, as they were when isolated in osmotically balancing medium. Evans blue failed to enter intact generative cells under any of the conditions tested. The dye ultimately entered the vegetative cells of some pollen grains, but these were non-germinable. Growing pollen tubes invariably resisted penetration. Neither of the high molecular weight conjugates entered germinable pollen grains or intact pollen tubes. The results suggest that it is highly unlikely that DNA fragments of high molecular weight can enter viable pollen, pollen tubes or generative cells under any normal conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189264
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  • 5
    Electronic Resource
    Electronic Resource
    Actomyosin and movement in the angiosperm pollen tube: an interpretation of some recent results (1989)
    Springer
    Sexual plant reproduction 2 (1989), S. 199-207 
    Details
    ISSN: 1432-2145
    Keywords: Pollen tube ; Actin ; Myosin ; Organelle movement ; Vegetative nucleus movement ; Generative cell movement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Recent confirmations of the presence of myosin in angiosperm pollen tubes indicate that an energy-transducing actomyosin system is involved in the motility system of the vegetative cells. Myosin has been localised by immunofluorescence on the surfaces of vegetative nuclei and generative cells. It has been shown to be associated with individual amyloplasts in grass pollen, and there are indications that it is present on other particulate bodies in the cytoplasm. The organelles in the leading part of the tube move along separate traffic lanes of acropetal and basipetal polarity, known from electron microscopy and phalloidin labelling to contain numbers of fibrils containing aggregates of actin microfilaments; in older segments the movement can be related to single, uniformly polarised, fibrils. Circulatory flow is maintained at the proximal end by the looping of the fibrils in the grain or at callose plugs. Such loops do not occur at the apex, where entering organelles undergo random movement before becoming associated with basipetal streams. Vegetative nuclei and generative cells interact with several fibrils, and it is suggested that they are held in the leading part of the protoplast in unstable equilibrium between acropetal and basipetal forces. Constantly changing form, especially of the vegetative nucleus, is one consequence of these varying stresses. Possible analogies with the intracellular motility system of the giant cells of the Characeae are noted, and it is suggested that lipid globuli and other nonorganellar bodies may be transported in the pollen tube by association with myosin-bearing membranes similar to those involved in endoplasm movement in the characean cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195579
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamic aspects of apical zonation in the angiosperm pollen tube (1990)
    Springer
    Sexual plant reproduction 3 (1990), S. 187-194 
    Details
    ISSN: 1432-2145
    Keywords: Pollen tube apical zonation ; Actin cytoskeleton ; Organelle movement ; Tip growth mechanism ; Epilobium angustifolium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the apical 10–20 μm of actively extending pollen tubes of Epilobium angustifolium, in a zone where the polysaccharide-containing wall precursor bodies (P-particles) dominate and where their movements on superficial observation seem to be random, there is in fact a concerted flux, acropetal movement taking place along the flanks of the tip zone, with a basipetal return flow along the centre. Detailed tracking of individuals shows that lipid globuli (diameters up to 1.5 μm) and amyloplasts (dimensions up to 5.5 × 2.5 μm) follow similar patterns of movement, but are sorted out in the sub-apical region, the smaller bodies penetrating further towards the apex. The findings are interpreted as indicating that the well-documented apical zonation of the pollen tube is maintained in the fluid circumstances of the growing tube by the filtering of cytoplasmic inclusions through the actin cytoskeleton, which, in conformity with recent fine-structural and other observations, is envisaged as consisting of a network of cross-linked microfilaments and microfilament aggregates at the tube tip giving place progressively to a system of more ordered, longitudinally oriented fibrils in the older parts of the tube. The implications for the operation of the actomyosin motility system and the tip growth mechanism are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00205228
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  • 7
    Electronic Resource
    Electronic Resource
    Comparative physical mapping of the 5S and 18S-25S rDNA in nine wild Hordeum species and cytotypes (1999)
    Springer
    Theoretical and applied genetics 98 (1999), S. 1-9 
    Details
    ISSN: 1432-2242
    Keywords: Key words In situ hybridization ; Hordeum ; Karyotype evolution ; rDNA ; Barley
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Absract  The physical locations of the 5S and 18S-25S rDNA sequences were examined in nine wild Hordeum species and cytotypes by double-target in situ hybridization using digoxigenin-labelled 5S rDNA and biotin-labelled 18S-25S rDNA as probes. H. vulgare ssp. spontaneum (2n=2x=14; I-genome) had a similar composition of 5S and 18S-25S rDNA to cultivated barley (H. vulgare ssp. vulgare, I-genome), with two major 18S-25S rDNA sites and minor sites on four of the other five chromosomes; three chromosomes had 5S rDNA sites. The closely related H. bulbosum (2x; also I-genome) showed only one pair of 5S rDNA sites and one pair of 18S-25S rDNA sites on different chromosomes. Four wild diploid species, H. marinum (X-genome), H. glaucum and H. murinum (Y-genomes) and H. chilense (H-genome), differed in the number (2–3 pairs), location, and relative order of 5S and the one or two major 18S-25S rDNA sites, but no minor 18S-25S rDNA sites were observed. H. murinum 4x had three chromosome pairs carrying 5S rDNA, while the diploid had only a single pair. Two other tetraploid species, H. brachyantherum 4x and H. brevisubulatum 4x (both considered to have H-type genomes), had minor 18S-25S rDNA sites, as well as the major sites. Unusual double 5S rDNA sites – two sites on one chromosome arm separated by a short distance – were found in the American H-genome species, H. chilense and H. brachyantherum 4x. The results indicate that the species H. brachyantherum 4x and H. brevisubulatum 4x have a complex evolutionary history, probably involving the multiplication of minor rDNA sites (as in H. vulgare sensu lato), or the incorporation of both I and H types of genome. The rDNA markers are useful for an investigation of chromosome evolution and phylogeny.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051033
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  • 8
    Electronic Resource
    Electronic Resource
    The evaluation of pollen quality, and a further appraisal of the fluorochromatic (FCR) test procedure (1984)
    Springer
    Theoretical and applied genetics 67 (1984), S. 367-375 
    Details
    ISSN: 1432-2242
    Keywords: Pollen testing ; Pollen germination ; Fluorochromatic reaction (FCR) ; Lilium longiflorum ; Narcissus pseudonarcissus ; Helleborus niger ; Primula vulgaris ; Medicago sativa ; Lucerne ; Alfalfa ; Lyco-persicum esculentum ; Tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Methods currently available for evaluating pollen quality in vitro include, (a) tests of germinability; (b) tests of the stainability of the vegetative cell contents; (c) tests for enzyme activity, and (d) the fluorochromatic procedure (FCR), which tests principally the integrity of the plasmalemma of the vegetative cell. Using germinability in vitro as a standard, a comparison has been made between histochemical methods of classes (b), (c) and (d) in application to various pollens, immature, mature, and treated in ways known to affect viability and membrane state. Predictably, the lowest correlation was obtained with tests of stainability. The highest was given by the FCR, which generally provided an excellent guide to potential germinability. The FCR procedure is subject to various limitations, however, (a) A high correlation between FCR and germinability can only be expected when mature, ripe pollen is used; with immature pollen, the FCR will predict excessively high potential germinability. (b) The FCR may also predict a higher potential level of pollen function than in vitro germinability when the germination medium is sub-optimal. In this situation, however, it will generally give a better guide to fertilising capacity, (c) The FCR is not a test of pollen viability. Like germinability in vitro, it can yield a negative score with pollen which is nevertheless capable of functioning. For example, false negatives will be obtained with some species if the pollen is not properly pre-conditioned by rehydration before testing, an important point in monitoring stored pollen. The paper includes a brief discussion of the rationale of pollen testing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272876
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  • 9
    Electronic Resource
    Electronic Resource
    Wide hybridization: pollination of Zea mays L. by Sorghum bicolor (L.) Moench (1985)
    Springer
    Theoretical and applied genetics 70 (1985), S. 252-258 
    Details
    ISSN: 1432-2242
    Keywords: Zea mays ; Sorghum bicolor ; Wide crossing ; Pollination technique ; Post-pollination effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Foreign pollen tubes in the stigma of Zea mays can be prevented from reaching the ovary cavity by the unusual length of the pollen tube pathway. A simple and rapid procedure is described for overcoming this difficulty by pollinating the basal parts of the stigmas without removing the ensheathing bracts (“husks”). The method maintains high humidity in the vicinity of the ovaries, and by conserving photosynthetic tissues probably also ensures a more normal O2 /CO2 balance in the neighbourhood of the stigmas than do bagging procedures. It is shown that Sorghum pollen tubes readily reach the ovary after pollination by the method. Their presence induces some of the characteristic post-pollination effects caused by Zea pollen tubes, but they frequently also stimulate premature enlargement of the nucellus and lysis of nucellar cells. Although Sorghum tubes have been traced across the inner ovary wall, they have not been seen to enter the micropyle, and hybrid embryos have not yet been obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304908
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  • 10
    Electronic Resource
    Electronic Resource
    Genomic in situ hybridization to identify alien chromosomes and chromosome segments in wheat (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 778-786 
    Details
    ISSN: 1432-2242
    Keywords: Genomic probing ; In situ hybridization ; Interphase cytogenetics ; Physical mapping ; Triticum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genomic in situ hybridization was used to identify alien chromatin in chromosome spreads of wheat, Triticum aestivum L., lines incorporating chromosomes from Leymus multicaulis (Kar. and Kir.) Tzvelev and Thinopyrum bessarabicum (Savul. and Rayss) Löve, and chromosome arms from Hordeum chilense Roem. and Schult, H. vulgare L. and Secale cereale L. Total genomic DNA from the introgressed alien species was used as a probe, together with excess amounts of unlabelled blocking DNA from wheat, for DNA:DNA in-situ hybridization. The method labelled the alien chromatin yellow-green, while the wheat chromosomes showed only the orange-red fluorescence of the DNA counterstain. Nuclei were screened from seedling root-tips (including those from half-grains) and anther wall tissue. The genomic probing method identified alien chromosomes and chromosome arms and allowed counting in nuclei at all stages of the cell cycle, so complete metaphases were not needed. At prophase or interphase, two labelled domains were visible in most nuclei from disomic lines, while only one labelled domain was visible in monosomic lines. At metaphase, direct visualization of the morphology of the alien chromosome or chromosome segment was possible and allowed identification of the relationship of the alien chromatin to the wheat chromosomes. The genomic in-situ hybridization method is fast, sensitive, accurate and informative. Hence it is likely to be of great value for both cytogenetic analysis and in plant breeding programmes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227384
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