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  • 1
    Electronic Resource
    Electronic Resource
    Periodic deposition of arabinogalactan epitopes in the cell wall of pollen tubes of Nicotiana tabacum L. (1992)
    Springer
    Planta 188 (1992), S. 532-538 
    Details
    ISSN: 1432-2048
    Keywords: Arabinogalactan epitope (immunofluores-cence localization) ; Cell wall ; Monoclonal antibody (JIM 8, MAC 207) ; Nicotiana ; Pollen tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The monoclonal antibodies MAC 207 and JIM 8, recognizing arabinogalactan epitopes, were used to localize the corresponding antigenic sites in pollen tubes of Nicotiana tabacum L. grown in vitro or semi in vivo. The analysis of the immunofluorescence labelling was performed by means of confocal laser scanning microscopy. Most pollen tubes were labelled along their length, with the exception of the tip region, in a ring-like pattern with remarkable periodicity. The diameter of the rings was approx. 12 μm and the distance between two rings was about 6 μm. No labelling of the cytoplasm, the vegetative nucleus or the generative cell was observed. The presence of labelling in the non-apical tube wall after pectinase and cellulase digestion indicates that the epitopes for MAC 207 and JIM 8 are located in the inner callosic sheath of the pollen-tube wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197045
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  • 2
    Electronic Resource
    Electronic Resource
    Enforced growth-rate fluctuation causes pectin ring formation in the cell wall of Lilium longiflorum pollen tubes (1996)
    Springer
    Planta 200 (1996), S. 41-49 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall (pectin ring) ; Enforced growth fluctuation ; Intracellular free Ca2+ ; Lilium ; Pollentube ; Turgor pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Normally growing lily (Lilium longiflorum Thunb.) pollen tubes cultured in standard sucrose medium display a relatively steady tip-growth pattern and a rather even pectin sheath in the cell wall. In an attempt to better understand pulsatory growth, observed in some species, e.g., Petunia, and its possible role in causing the formation of thickened cell wall rings, we have imposed marked fluctuations in the growth-rate of lily pollen tubes. The appropriate growth-perturbing conditions were achieved by modulating the medium osmolarity or by applying caffeine, a non-turgor inhibitor, in a specially designed incubation chamber with a controlled medium flow. The relatively non-esterified pectin deposition in the wall of the growth-interrupted pollen tubes was detected by immunofluorescence microscopy using a monoclonal antibody, JIM 5. The observations show that the periods of slow or inhibited growth correspond to the times when the thickened walls are deposited. Since the growth fluctuations were induced by both turgor- and non-turgor-related means, the proposed endogenous regulatory role of turgor pressure is questioned. Other factors, such as the tip-focused Ca2+ gradient which was demonstrated by ratiometric ion imaging, and the alteration in the extensibility of the cell wall, which correlated with pectin esterification/de-esterification, emerge as candidates for the regulation of growth fluctuations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196647
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  • 3
    Electronic Resource
    Electronic Resource
    The expression of a potato (Solanum tuberosum) S-RNase gene in Nicotiana tabacum pollen (1995)
    Springer
    Sexual plant reproduction 8 (1995), S. 77-84 
    Details
    ISSN: 1432-2145
    Keywords: Self-incompatibility ; S RNase ; Solanum tuberosum ; Transgenic plants ; Pollen ; Tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Self-incompatibility in the Solanaceae is controlled by a single multiallelic genetic locus, the S locus. The stylar gene products of the S locus are abundant glycoproteins with ribonuclease activity, secreted in the transmitting tract tissue of the pistil. To investigate the structural and functional integrity and possible phenotypic effects of expression of the S-gene product in the male gametophyte, N. tabacum plants were transformed with a construct containing the genomic S 2 -RNase coding sequence from S. tuberosum under the control of the promoter of the pollen-specific LAT52 gene from tomato. The expression pattern of the S 2 RNase in the male gametophyte at both the protein and RNA level was found to be identical to that already reported for expression of the β-glucuronidase (GUS) gene directed by the LAT52 promoter in transgenic tomato and tobacco. The S 2 -RNase gene fusion led to a tissue-specific and developmentally regulated accumulation of the S 2 polypeptide in pollen of transgenic tobacco plants. The transgenic protein product was of the same size and charge as the potato stylar product, had ribonuclease activity, and was glycosylated. The transgenic plants, however, did not show any morphological variations in their flower organs, and their fertility was not influenced by the accumulation of the S 2 -RNase protein in pollen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230892
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  • 4
    Electronic Resource
    Electronic Resource
    Wall-bound proteins of pollen tubes after self- and cross-pollination in Lilium longiflorum (1983)
    Springer
    Theoretical and applied genetics 67 (1983), S. 11-16 
    Details
    ISSN: 1432-2242
    Keywords: Wall bound proteins ; Pollen tubes ; Incompatibility ; Lily ; Lilium longiflorum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Wall-bound proteins of Lilium longiflorum pollen tubes grown in vivo constitute 20–27% of the dry matter. Twenty-two-twenty-six percent of these proteins are NaCl soluble. Wall-bound proteins of in vivo pollen tubes are present in amounts 5–7 times that found in tubes grown in vitro. The protein pattern of wall-bound proteins is different between in vitro and in vivo grown pollen tubes. There are two kinds of pollen tube wall proteins: loosely bound and tightly bound. The latter are NaCl insoluble, contain hydroxyproline and are assumed to be covalently bound. No significant differences have been found in the amount of wall-bound proteins present between pollen tubes resulting after self-pollination and those resulting from cross-pollination. However, some band differences between self- and cross pollen tubes have been observed after gel electrophoresis. It can be supposed that some wall-bound proteins of pollen tubes are associated with the incompatibility reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00303915
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  • 5
    Electronic Resource
    Electronic Resource
    Microtubular organization during asymmetrical division of the generative cell inGagea lutea (1995)
    Springer
    Journal of plant research 108 (1995), S. 269-276 
    Details
    ISSN: 1618-0860
    Keywords: Gagea lutea ; Generative cell ; Microtubule organization ; Mitosis ; Sperm cell dimorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Video microscopy and conventional or Confocal Laser Scanning Microscopy after DAPI staining and anti-α-tubulin labelling were used to study the asymmetrical division of the generative cell (GC) inGagea lutea. Pollen was cultured for up to 8 hr in a medium containing 10% poly (ethylene glycol), 3.0% to 3.8% sucrose, 0.03% casein acid hydrolysate, 15 mM 2-(N-morpholinoethane)-sulphonic acid-KOH buffer (pH 5.9) and salts. In the pollen grain, the GC had a spherical or ovoid shape and contained a fine network of intermingled microtubules. As the GC entered into the pollen tube, it assumed a cylindrical shape with a length often exceeding 250 μm. A cage of microtubules then developed around the nucleus. The presence of dense and thick microtubular bundles in front of the generative nucleus within the GC coincided with the translocation of the nucleus to the leading end of the GC. No pre-prophase band was ever detected, but a distinct prophase spindle of microtubules was formed. In some GCs a tubulin-rich dot became visible at each pole of the spindle. After nuclear envelope breakdown, the bundles of microtubules spread between the chromosomes and became oriented into parallel arrays. The spindle became shorter at metaphase, and there was no tubulin labelling at the site of the metaphase plate. At anaphase, the microtubular apparatus lost its spindle-shape and a bridge of prominent bundles of microtubules connected the two daughter nuclei. At telophase, the site of the cell plate remained unstained by the anti-α-tubulin antibody, but a distinct phragmoplast of microtubules was formed more closely to the leading nucleus, resulting in the formation of unequal sperm cells (SCs). The leading SC was up to 2.5 times smaller than the following SC and it contained a smaller or equal number of nucleoli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02344352
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  • 6
    Electronic Resource
    Electronic Resource
    Ultrastructural immunolocalization of periodic pectin depositions in the cell wall ofNicotiana tabacum pollen tubes (1995)
    Springer
    Protoplasma 187 (1995), S. 168-171 
    Details
    ISSN: 1615-6102
    Keywords: Cell wall ; Immunocytochemical localization ; JIM5 antibody ; Pectins ; Pollen tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The monoclonal antibody (MAb) JIM5, marking acidic pectins, was used to localize ultrastructurally pectin molecules in the pollen tube wall ofNicotiana tabacum. Longitudinal sections of LR-White embedded pollen tubes were exposed to antibody treatment; accumulations of pectins were identified by counting the density of the gold particles representing the pectin epitopes along the pollen tube wall. Significant accumulations of gold grains were marked and the distances between them were measured. In many pollen tubes a more or less regular distribution of the accumulations was observed along the tube indicating a periodical deposition of pectin. The distances between the accumulations were 4–6 μm. Most of the label was found in the inner part of the outer layer of the bilayered cell wall. These findings correspond to and confirm the earlier observation by our group reporting ring-shaped periodical deposits in pollen tubes after immunofluorescence labelling with the MAb JIM5 under the confocal laser scanning microscope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280245
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  • 7
    Electronic Resource
    Electronic Resource
    Immunogold localization of arabinogalactan proteins, unesterified and esterified pectins in pollen grains and pollen tubes ofNicotiana tabacum L. (1995)
    Springer
    Protoplasma 189 (1995), S. 26-36 
    Details
    ISSN: 1615-6102
    Keywords: Nicotiana tabacum ; Pollen ; Pollen tube ; Cell wall ; Immunogold localization ; Pectins ; Arabinogalactan proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The monoclonal antibodies JIM 5 (against unesterified pectin), JIM 7 (against methyl esterified pectin), MAC 207 (against arabinogalactan proteins, AGPs), and JIM 8 (against a subset of AGPs) were utilized singly or in combinations for immunogold labelling of germinated pollen grains and pollen tubes ofNicotiana tabacum. Pectins were localized in the inline of pollen grain, unesterified pectin being more abundant than the esterified one. AGPs were co-localized with pectin in the inline, but were present preferably close to the plasma membrane. In pollen tubes, AGPs, unesterified and esterified pectins were co-localized in the outer and middle layers of the cell wall. The density of the epitopes was not uniform along the length of the pollen tube, but showed alterations. In the pollen tube tip wall esterified pectin was abundantly present, but not AGPs. In the cytoplasm esterified pectin and AGPs were detected in Golgi derived vesicles, indicating their role in the pathway of the cell wall precursors. In the “cell wall” of generative cell only AGPs, but no pectins were localized. The co-localization of pectins and AGPs in the cell wall of pollen grain and pollen tube might play an important role, not only in maintenance of the cell shape, but also in cell-cell interaction during pollen tube growth and development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280289
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  • 8
    Electronic Resource
    Electronic Resource
    The wall ofPinus sylvestris L. pollen tubes (1999)
    Springer
    Protoplasma 208 (1999), S. 26-36 
    Details
    ISSN: 1615-6102
    Keywords: Callose ; Cell wall ; Cellulose ; Pinus sylvestris ; Pectin ; Pollen tube ; Tip growlh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The wall ofPinus sylvestris pollen and pollen tubes was studied by electron microscopy after both rapid-freeze fixation and freeze-substitution (RF-FS) and chemical fixation. Fluorescent probes and antibodies (JIM7 and JIM5) were used to study the distribution of esterified pectin, acidic pectin and callose. The wall texture was studied on shadow-casted whole mounts of pollen tubes after extraction of the wall matrix. The results were compared to current data of angiosperms. TheP. sylvestris pollen wall consists of a sculptured and a nonsculptured exine. The intine consists of a striated outer layer, that stretches partly over the pollen tube wall at the germination side, and a striated inner layer, which is continuous with the pollen tube wall and is likely to be partly deposited after germination. Variable amounts of callose are present in the entire intine. No esterified pectin is detected in the intine and acidic pectin is present in the outer intine layer only. The wall of the antheridial cell contains callose, but no pectin is detectable. The wall between antheridial and tube cell contains numerous plasmodesmata and is bordered by coated pits, indicating intensive communication with the tube cell. Callose and esterified pectin are present in the tip and the younger parts of the pollen tubes, but both ultimately disappear from the tube. Sometimes traces in the form of bands remain present. No acidic pectin is detected in either tip or tube. The wall of the pollen tube tip has a homogenous appearance, but gradually attains a fibrillar character at aging, perhaps because of the disappearance of callose and pectin. No secondary wall formation or callose lining can be seen wilh the electron microscope. The densily of the cellulose microfibrils (CMF) is much lower in the tip than in the tube. Both show CMF in all but axial and nontransverse orientations. In conclusion,P. sylvestris and angiosperm pollen tubes share the presence of esterified pectin in the tip, the oblique orientations of the CMF, and the gradual differentiation of the pollen tube wall, indicating a possible relation to tip growth. The presence of acidic pectin and the deposition of a secondary-wall or callose layer in angiosperms but not inP. sylvestris indicales that these characteristics are not related to tip growth, but probably represent adaptations to the fast and intrastylar growth of angiosperms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279072
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  • 9
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    Propofol inhibits proliferation and induces neuroapoptosis of hippocampal neurons in vitro via downregulation of NF-κB p65 and Bcl-2 and upregulation of caspase-3 (2014)
    Wiley
    Details
    Publication Date: 2014-11-29
    Description: Propofol is widely used in paediatric anaesthesia and intensive care unit because of its essentially short-acting anaesthetic effect. Recent data have shown that propofol induced neurotoxicity in developing brain. However, the mechanisms are not extremely clear. To gain a better insight into the toxic effects of propofol on hippocampal neurons, we treated cells at the days in vitro 7 (DIV 7), which were prepared from Sprague–Dawley embryos at the 18th day of gestation, with propofol (0.1–1000 μM) for 3 h. A significant decrease in neuronal proliferation and a remarkable increase in neuroapoptosis were observed in DIV 7 hippocampal neurons as measured by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide assay and apoptosis assay respectively. Moreover, propofol treatment decreased the nuclear factor kappaB (NF-κB) p65 expression, which was accompanied by a reduction in B-cell lymphoma 2 (Bcl-2) mRNA and protein levels, increased caspase-3 mRNA and activation of caspase-3 protein. These results indicated that downregulation of NF-κB p65 and Bcl-2 were involved in the potential mechanisms of propofol-induced neurotoxicity. This likely led to the caspase-3 activation, triggered apoptosis and inhibited the neuronal growth and proliferation that we have observed in our in vitro systems. Copyright © 2014 John Wiley & Sons, Ltd.
    Print ISSN: 0263-6484
    Electronic ISSN: 1099-0844
    Topics: Biology , Medicine
    Published by Wiley
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  • 10
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    Probability prediction of peak break‐up water level through vine copulas (2019)
    Wiley
    Details
    Publication Date: 2019
    Description: Abstract Prediction of the peak break‐up water level, which is the maximum instantaneous stage during ice break‐up, is desirable to allow effective ice flood mitigation, but traditional hydrologic flood routing techniques are not efficient in addressing the large uncertainties caused by numerous factors driving the peak break‐up water level. This research provides a probability prediction framework based on vine copulas. The predictor variables of the peak break‐up water level are first chosen, the pair copula structure is then constructed by using vine copulas, the conditional density distribution function is derived to perform a probability prediction, and the peak break‐up water level value can then be estimated from the conditional density distribution function given the conditional probability and fixed values of the predictor variables. This approach is exemplified using data from 1957 to 2005 for the Toudaoguai and Sanhuhekou stations, which are located in the Inner Mongolia Reach of the Yellow River, and the calibration and validation periods are divided at 1986. The mean curve of the peak break‐up water level estimated from the conditional distribution function can capture the tendency of the observed series at both the Toudaoguai and Sanhuhekou stations, and more than 90% of the observed values fall within the 90% prediction uncertainty bands, which are approximately twice the standard deviation of the observed series. The probability prediction results for the validation period are consistent with those for the calibration period when the nonstationarity of the marginal distributions for the Sanhuhekou station are considered. Compared with multiple linear regression results, the uncertainty bands from the conditional distribution function are much narrower; moreover, the conditional distribution function is more capable of addressing the nonstationarity of predictor variables, and the conclusions are confirmed by jackknife analysis. Scenario predictions for cases in which the peak break‐up water level is likely to be higher than the bankfull water level can also be conducted based on the conditional distribution function, with good performance for the two stations.
    Print ISSN: 0885-6087
    Electronic ISSN: 1099-1085
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley
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