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  • Lilium longiflorum  (4)
  • Tip growth  (4)
  • (Me2SiNCN)4  (1)
  • Betula pendula  (1)
  • COMPUTER PROGRAMMING AND SOFTWARE  (1)
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  • 1
    ISSN: 1432-2048
    Keywords: Key words: Calyculin A ; Lilium ; Okadaic acid ; Pollen ; Protein phosphorylation ; Tip growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Inhibitors of type-2A protein phosphatase (PPase-2A), calyculin A (cal A) and okadaic acid (OA), inhibit pollen grain germination and growth of pollen tubes of Lilium longiflorum Thunb. at nanomolar concentrations. Half-maximal inhibition of cytoplasmic PPase-2A activity was below 0.1 nM for cal A and at 0.7 nM for OA. Other protein phosphatase inhibitors (tautomycin, cypermethrin, and dephostatin) were less effective. The OA- and cal A-sensitive as well as dephostatin-sensitive PPase activity in the cytoplasm did not change during germination and growth of pollen tubes. Addition of cal A and OA disturbed the direction of pollen tube growth and the distribution of cytoplasmic organelles and caused cell wall thickenings as observed by light and electron microscopy. Inhibition of PPase-2A caused multiple effects at the cellular level, cytoskeletal elements being a putative target of PPase-2A activity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 187 (1995), S. 155-167 
    ISSN: 1615-6102
    Keywords: Calcium ; Channels ; Ion pumps ; Pollen ; Potassium ; Tip growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary One of the most interesting aspects of plant fertilization is the growth and orientation of the pollen tube from the stigma to the ovary. Considerable research has been carried out in this field but little is yet known about the mechanisms involved in the growth process. Recent research has been focused on the regulation of molecular events in order to discover the specific genes involved in tube growth. Important results in the biochemical and physiological aspects of molecular regulation have been reported. The following review attempts to cover these aspects. It is primarily based on talks presented by the authors at the 13th International Congress on Sexual Plant Reproduction and is mainly addressed to non-experts in the fields of electrophysiology and ion signalling. We aim to present a general overview of electrical currents, ion dynamics, and ion transporters in pollen, and their possible role during pollen tube germination and growth. Together with results on other tip-growing cells, a general model of pollen tube germination and growth as a self-organizing process is proposed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1615-6102
    Keywords: Immunolocalization ; H+-ATPase ; Tip growth ; Lilium longiflorum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A heterogeneous distribution of H+-ATPase was visualized in germinated pollen ofLilium longiflorum using monoclonal antibodies raised against plasma membrane H+-ATPase. Immunolocalization studies of protoplasts and subprotoplasts derived from pollen tubes and sectioned pollen grains and pollen tubes show that H+-ATPases are abundant in the plasma membrane of pollen grains but are absent or sparsely distributed in the plasma membrane of pollen tubes. This polar distribution of H+-ATPases is probably the basis of the endogenous current pattern measured in growing lily pollen and involved in pollen tube tip growth.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 187 (1995), S. 132-137 
    ISSN: 1615-6102
    Keywords: Electroporation ; Electropermeabilization ; Lilium longiflorum ; Pollen grains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electroporation was used to introduce plasma membrane impermeable molecules into the cytoplasm of pollen grains ofLilium longiflorum. Ungerminated pollen grains were exposed to the fluorescent dye quin2 or FITC-labelled dextrans and electroporated with exponentially decaying voltage pulses of 250 to 2000 V/cm and time constants of 0.01 to 10 μs. The number of electroporated pollen grains increased with the strength and duration of the voltage pulses, and with the osmolarity of the external medium. Optimal results were obtained with pulses of 1000 V/cm and 10 μs time constant, and with 900 mM mannitol in the electroporation buffer. The size of the pores produced in the plasma membrane by electroporation allowed uptake of 40 kDa dextran but not 70 kDa dextran. The rate of germination of pollen grains was low immediately after electroporation, but increased with time in pollen growth medium. The conditions of electroporation reported here may be used to load genetic material into pollen grains for the production of transgenic plants.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1615-6102
    Keywords: Elodea densa ; Eremosphaera ; Laser microsurgery ; Lilium longiflorum ; Patch-clamp ; Nicotiana tabacum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In plant cells the cell wall is a formidable obstacle in many physiological studies such as patch-clamp measurements and cell labelling with antibodies. Enzymatic digestion of the cell wall, in order to release a protoplast, has a number of disadvantages; therefore we worked out an alternative method to gain access to the plasma membrane. The wall of specialized cells from three higher plant species and one unicellular alga were perforated using the focussed UV light of a nitrogen laser. In order to enhance the absorption of the UV light by the walls, a dye was used that binds specifically to cell wall components. Extrusion of the protoplast or parts thereof was controlled by a regulated gradual decrease of the osmolarity of the solution surrounding the cells. Cytoplasmic streaming and chloroplast circulation were maintained in the protoplasts, demonstrating their viability after the wall perforation with the laser. Continuous deposition of new cell wall material by the polar tip of pollen tubes after surgical removal of the wall at the tip is another demonstration of the viability of the cells. Formation of high resistance seals between the plasma membrane and a patch pipet was surprisingly difficult. The role of ‘Hechtian strands’ and continuing synthesis of cell wall material in seal formation is further investigated. Other applications for the surgical laser are: fusion of two cells or vacuoles, analysis of the composition of specific parts of the cell wall, and release of the vacuole from an identified cell type for patchclamp studies.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 198 (1997), S. 1-8 
    ISSN: 1615-6102
    Keywords: Lilium longiflorum ; Pollen tube ; Pressure probe ; Tip growth ; Turgor pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The turgor pressure of growing pollen tubes of the lily (Lilium longiflorum Thunb.) has been recorded using a turgor pressure probe. Insertion of the probe's micropipette was routinely accomplished, providing recording periods of 20 to 30 min. Probe insertion did not affect tube growth. The stable turgor values ranged between 0.1 and 0.4 MPa, the mean value being 0.209 ± 0.064 MPa (n=106). A brief increase in turgor, generated by injection of oil through the pressure probe, caused the tube to burst at its tip. Burst pressures ranged between 0.19 and 0.58 MPa, that is, individual lily pollen tubes do not withstand turgor pressure approaching twice their regular turgor pressure. In contrast, parallel experiments using the incipient plasmolysis technique yielded a mean putative turgor pressure of 0.79 MPa either using sucrose (n=24) or mannitol (n=25). Surprisingly, turgor pressure was not significantly correlated with tube growth rate which ranged from zero to 13 μm/min. Nor did it correlate with tube length over the tested range of 100 to 1600 μm. In addition the influence of the medium's osmolality was surprisingly low: raising the external osmotic pressure from 0.36 to 1.08 MPa, with sucrose or mannitol, only caused mean turgor pressure to decline from 0.27 to 0.18 MPa. We conclude that growing lily pollen regulates its turgor pressure remarkably well despite substantial variation in tube growth rate, tube length, and osmotic milieu.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1615-6102
    Keywords: Allergens ; Allergy ; Betula pendula ; Immunolabelling ; Pollen grains ; Tapetum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Although intact pollen grains are assumed to be the primary carrier of pollen allergens, specific immunoreactive components have been found in other aerosol fractions, e.g., starch grains and remains of tapetal cells Cryo-scanning-electron-microscopy results demonstrate the presence of a clear network of strands connecting the tapetum with the microspores. The distribution of protein in tapetal orbicules, pollen wall, and pollen cytoplasm was tested by histochemical stains for light microscopy and transmission electron microscopy. The protein is mainly localized at the apertures and starch grains in the cytoplasm of pollen and in the core and on the surface of tapetal orbicules. Monoclonal antibodies Bv-10, BIP3, and BIP4 have been used to locate the cellular sites of pollen and tapetal allergens inBetula pendula (syn.B. verrucosa). The application of rapid-freeze fixation prevented relocation of allergens from their native sites. The allergens are predominantly found in the starch grains and to lesser extent in the exine. We also tested interactions between mature birch pollen and human fluids: saliva, nostrils fluid, and eyes solution. The aim was to mimic more closely the in vivo situation during allergenic response. In all cases we observed several pollen grains that were burst and had released their cytoplasmic contents. In the nose the allergens are released from the pollen within minutes. In rhinitis, nasal pH is increased from the normal pH 6.0 to 8.0. When we used nasal fluid at pH 8.0, the number of ruptured pollen grains increased. The mechanism that might induce formation of small allergen-bearing particles from living plant cells is discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 620 (1994), S. 1357-1363 
    ISSN: 0044-2313
    Keywords: (Me2SiNCN)4 ; Me3SiNCNSiMe3 ; X-Ray ; NMR ; IR ; Raman ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Crystal and Molecular Structures of (Me2SiNCN)4 (1) and Me3SiNCNSiMe3 (2)Synthesis, spectroscopic characterization (NMR, IR, Raman and MS) and crystal structure of the novel compound 1 are described. The molecules form almost planar 16 membered rings with four SiMe2-groups connected to four NCN groups. The corresponding compound 2 exhibits a phase transition from the HT phase 2a to the LT phase 2b at 131 K. Consecutive X-ray structure determinations of the molecular structures of both modifications were performed on a crystal, grown in situ on the diffractometer at 231 K.
    Notes: Für die neuartige Verbindung 1 werden Synthese, spektroskopische Charakterisierung (NMR, IR, Raman und MS) und die Kristallstruktur beschrieben. Das Molekül besteht aus einem nahezu planaren 16gliedrigen Ring, in dem vier SiMe2-Gruppen mit vier NCN-Gruppen verknüpft sind. Die Vergleichsverbindung 2 zeigt eine Phasenumwandlung von der HT-Phase 2a in die TT-Phase 2b bei 131 K. Die Molekülstrukturen beider Modifikationen wurden nacheinander durch Röntgenstrukturanalyse an einem in situ bei 231 K auf dem Diffraktometer gezüchteten Kristall bestimmt.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 2019-06-28
    Description: This paper describes a set of C++ extensions to the CLIPS language and their embodiment in CLIPS++. These extensions and the implementation approach of CLIPS++ provide a new level of embeddability with C and C++. These extensions are a C++ include statement and a defcontainer construct; (include (c++-header-file.h)) and (defcontainer (c++-type)). The include construct allows C++ functions to be embedded in both the LHS and RHS of CLIPS rules. The header file in an include construct is the same header file the programmer uses for his/her own C++ code, independent of CLIPS. The defcontainer construct allows the inference engine to treat C++ class instances as CLIPS deftemplate facts. Consequently existing C++ class libraries may be transparently imported into CLIPS. These C++ types may use advanced features like inheritance, virtual functions, and templates. The implementation has been tested with several class libraries, including Rogue Wave Software's Tools.h++, GNU's libg++, and USL's C++ Standard Components. The execution speed of CLIPS++ has been determined to be 5 to 700 times the execution speed of CLIPS 6.0 (10 to 20X typical).
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA. Lyndon B. Johnson Space Center, Third CLIPS Conference Proceedings, Volume 1; p 29-33
    Format: application/pdf
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