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  • 1
    ISSN: 0309-1651
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0309-1651
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We report on the application of a pyrogallol red-vanadium complex (PR-V) for ultracytochemical staining of proteinaceous structures in animal tissues and cell cultures. This dye may be used as a general purpose stain in electron microscopy. In contrast to osmium tetroxide, the price of the material is low and no toxic vapors are produced. The PR-V complex was prepared by addition of vanadium (IV) oxide sulfate to pyrogallol red dissolved in acetate buffer (pH 5.6). The formation of the complex was indicated by a color change from purplered (λmax=520 nm) to violet (λmax=539 nm) which occurred at equimolar concentrations of the dye and the metal salt. Under these conditions PR-V was stable for several days. The mechanism of PR-V binding was checked in dot blots using different proteins as well as heparin for control. While heparin remained unstained, proteins were stained in a dose-dependent manner. Deamination of proteins with nitric oxide strongly reduced PR-V staining in dot blots as well as in cell cultures. Optimal staining results of animal cells and tissues were obtained in specimens that had been mildly fixed for at least 1 h or longer with a mixture of 0.1% glutaraldehyde and 1.0% paraformaldehyde dissolved in phosphate-buffered saline, pH 7.2, washed with acetate buffer, pH 5.6, and subsequently treated with PR-V in the presence of 50% ethanol at room temperature. Control specimens without PR-V but treated en bloc with uranyl acetate or sodium molybdate showed similar contrast but less details in the ultrastructure of the tissue. All specimens were embedded in epoxy resin and ultrathin sections were stained conventionally with uranyl and lead salt solutions. In electron micrographs, membrane-associated particles, stress fibers and filaments of the cell cortex, collagen fibrils, tight junctions and desmosomes, and other proteinaceous components were clearly visualized only in the PR-V-treated speciments. In conclusion, the ability to bind selectively and specifically to proteinaceous structures makes PR-V a versatile stain to study the localization and distribution of these structures in cells and tissues at the ultrastructural level.
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  • 4
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In electron micrographs it could be shown that hazelnut (Corylus avellana) pollen grains are covered on their surface by a diffusible 10 nm thick lamellar layer. On pollen surface as well as in pollen extract this layer could be precipitated and stained by the polycationic dye Cuprolinic blue. By subsequent application of both immunogold labeling with serum from a hay-fever patient allergic to tree pollen grains and histochemical detection with Cuprolinic blue this pollen surface layer proved to be an effective antigen.
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  • 5
    ISSN: 0014-4827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 117 (1983), S. 154-157 
    ISSN: 1615-6102
    Keywords: Paraflagellar body membrane ; Freeze-fracture ; Euglena ; Phototaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The membrane overlying the paraflagellar body (PFB) ofEuglena gracilis is structurally specialized when studied with the freeze-fracture technique. This membrane area is characterized by exclusion of larger-sized (10–14nm) intramembrane particles and appears relatively smooth. In a limited region this membrane is closely appressed to the plasmalemma of the reservoir adjacent to the eyespot globules. The membrane specializations in the PFB-membrane ofEuglena are discussed in relation to photoreception and sensory transduction during phototaxis.
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  • 7
    ISSN: 1615-6102
    Keywords: Immunocytochemistry ; Centrin ; Ca2-modulated contractile protein ; Flagellar apparatus ; Green algae ; Fibrous flagellar roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The two main types of fibrous flagellar roots present in the flagellar apparatus of green algae (system I and system II fibers) are immunologically distinct as indicated by the localization of a Ca2+-modulated contractile protein (centrin) exclusively in one type (system II fibers) but not in the other type (system I fibers). A polyclonal antibody generated against the major protein of the striated flagellar roots (system II fibers) of the quadriflagellate green algaTetraselmis striata was used to localize centrin by immunofluorescence and pre- and postembedding immunogold electron microscopy in the flagellar apparatus ofSpermatozopsis similis, S. exsultans, Chlamydomonas reinhardtii, Dunaliella bioculata, Polytomella parva and gametes ofMonostroma grevillei andEnteromorpha sp. Whereas the antibody recognizes centrin in connecting fibers and system II fibers, no labeling occurs in system I fibers in all taxa investigated. This study presents the first evidence that system I fibers lack centrin and indicates that the two main types of fibrous flagellar roots in green algae are biochemically distinct.
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  • 8
    ISSN: 1615-6102
    Keywords: Chlorosarcinopsis gelatinosa ; Eyespot membranes ; Phototaxis ; Zoospore settlement ; Zoospores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eyespot membranes in zoospores of the green algaChlorosarcinopsis gelatinosa were studied with the freeze-fracture technique. The PF of the plasmalemma overlying the eyespot lipid globules contains significantly greater numbers of intramembraneous particles (IMP; 8,200 IMP/μm2) compared to other areas of the plasmalemma (2,100 IMP/μm2). In the eyespot area the EF of the plasmalemma reveals no IMP, but regularly arranged depressions corresponding to the PF particles. Sizes of PF particles are not significantly different between the eyespot area and other areas of the plasmalemma. Zoospore settlement starts approximately two hours after release and involves in sequence, rounding up of the cells, retraction of the flagella and secretion of a cell wall. Eyespot membrane specializations on the PF of the plasmalemma disappear during flagellar retraction and before cell wall secretion. The functional significance of eyespot membrane specializations is discussed in accordance with the view that these membranes are engaged in photoreception and primary sensory transduction relating to green algal phototaxis.
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  • 9
    ISSN: 1615-6102
    Keywords: Eyespot ; Phototaxis ; Tetraselmis cordiformis (Stein)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The eyespot region of the flagellateTetraselmis cordiformis Stein (Chlorophyceae) was investigated with the freeze-fracture technique. The only fracture faces observed in this region were the two complementary fracture faces (PF and EF) of the outer chloroplast envelope membrane. Intramembranous particle numbers on both fracture faces of this membrane were significantly higher in the eyespot region as compared to regions outside the eye-spot. Higher numbers of particles on the PF face in the eyespot region were mainly caused by an increase in particle numbers of the size class 6–8 mm, while on the EF face particle size distribution was not significantly different between eyespot and other regions. Functional implications are discussed and evidence is presented that the outer chloroplast envelope membrane may be the site of photoreceptor location in green algal phototaxis.
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  • 10
    ISSN: 1615-6102
    Keywords: Algae ; Chloroplast envelopes ; Filipin-sterol complexes ; Freeze-fracture ; Higher plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The occurrence and planar distribution of 3-β-hydroxysterols in chloroplast envelope membranes of different algae and higher plants has been studied with the freeze-fracture technique using the polyene antibiotic filipin as cytochemical marker. The inner chloroplast envelope membrane in all organisms studied is devoid of filipin-sterol complexes. The outer chloroplast envelope membranes of isolated higher plant chloroplasts (spinach, pea) and of chloroplasts of the mossPolytrichum piliferum are lacking filipin-sterol complexes, thus indicating a very low concentration of 3-β-hydroxysterols in chloroplast envelope membranes of higher plants. In contrast filipin-sterol complexes are abundant in the outer chloroplast envelope membrane of the flagellatesChlamydomonas reinhardii, Cryptomonas erosa, andEuglena gracilis. The chloroplast-ER surrounding the plastid ofCryptomonas erosa also exhibits filipin-sterol complexes. Functional and phylogenetic aspects of these observations are discussed.
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