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  • 1
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    Effect of Water-Table Depth on Shoot Growth, Root Growth, and Nodulation of Myrica Gale Seedlings (1983)
    Wiley
    Details
    Publication Date: 1983-07-01
    Print ISSN: 0022-0477
    Electronic ISSN: 1365-2745
    Topics: Biology
    Published by Wiley on behalf of British Ecological Society.
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    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    Fluorescence microscopic localization of actin in pollen tubes: Comparison of actin antibody and phalloidin staining (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 216-224 
    Details
    ISSN: 0886-1544
    Keywords: actin microfilaments ; cytochalasin ; immunofluorescence ; phalloidin ; cytoplasmic streaming ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A comparison of actin localization in pollen tubes of Nicotiana has been made using a monoclonal actin antibody and rhodamine-phalloidin (RP). The monoclonal antiactin, based on Western blotting of pollen tube extract, labels a polypeptide at 45 kD that comigrates with muscle actin. A 51-kD unknown protein and three bands less than 45 kD, presumed to be proteolytic fragments of actin, are also observed. Structural observaations using this antibody reveal a network of axially oriented strands of microfilaments (MFs). The MFs are distributed throughout the length of the pollen tube except at the very tip, where diffuse staining is usually observed. A similar pattern of MFs is evident after RP staining. When pollen tubes are treated with cytochalasins (CB or CD) cytoplasmic streaming is inhibited, as is tube elongation. Microscopic analysis reveals that the microfilament (MF) pattern is markedly altered; however, the antibody and RP produce different staining patterns. The antibody reveals many MF strands that distribute throughout the tube length and extend into the very tip. In contrast, RP shows mostly a diffuse staining pattern with only a few short clumps of filamentous material. Immunogold labelling of sections of pollen tubes prepared by rapid-freeze fixation and freeze substitution reveals that actin MF bundles are indeed present after cytochalasin treatment. Our results thus question reports in the literature, based on phalloidin staining, asserting that cytochalasin fragments or destroys actin MFs.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970120404
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  • 3
    Electronic Resource
    Electronic Resource
    A method for rapid freeze fixation of plant cells (1986)
    Springer
    Protoplasma 131 (1986), S. 153-165 
    Details
    ISSN: 1615-6102
    Keywords: Freeze substitution ; Hafnium tetrachloride ; Plant cell ultrastructure ; Rapid freeze fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We describe here an apparatus that permits rapid freeze fixation of whole cells, which are then prepared by freeze substitution and resin embedment for examination in the EM. The freezing device utilizes a rotary solenoid that rapidly plunges the specimen holder, a formvar-film-covered thin wire loop, into a well of stirred liquid propane at −180
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01285037
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructure of freeze-substitutedFrankia strain HFPCcI 3, the actinomycete isolated from root nodules ofCasuarina cunninghamiana (1985)
    Springer
    Protoplasma 127 (1985), S. 64-72 
    Details
    ISSN: 1615-6102
    Keywords: Actinomycete ; Casuarina ; Frankia ; Freeze-substitution ; Quick-freezing ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Frankia strain HFPCcI 3 is an actinomycete isolated from root nodules ofCasuarina cunninghamiana. In culture it exhibits typicalFrankia morphology and may produce three distinct morphological forms: branching septate hyphae, terminal or intercalary sporangia, and specialized structures termed vesicles which are the purported site of nitrogenase activity. An examination of the ultrastructure of all three morphological forms using both conventional chemical fixation (CF) and quick-freezing followed by freeze-substitution (FS) reveals some interesting differences between the two fixation methods. Unique to FS material are: 1. smooth membrane profiles; 2. lack of mesosomes; 3. lack of discernible nucleoid regions with condensed chromatin; 4. clarity of cytoplasmic elements such as ribosomes and granular bodies; 5. large cytoplasmic tubules in hyphae and young sporangia; 6. outer wall layer not widely separated from the spherical portion of the vesicle, and 7. bundles of microfilaments in vesicles. The quality of preservation after FS appears to be far superior to that obtained with CF. Accordingly the structures observed after FS are thought to represent more faithfully the structure of the living cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273702
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  • 5
    Electronic Resource
    Electronic Resource
    Actin-endoplasmic reticulum complexes inDrosera (1990)
    Springer
    Protoplasma 155 (1990), S. 116-126 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Cytoplasmic streaming ; Drosera ; Endoplasmic reticulum ; Freeze fixation ; Freeze substitution ; Hyperbaric freezing ; High pressure freezing ; Immunogold localization ; Microfilaments ; Plasmalemma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In epidermal cells ofDrosera tentacles that have been preserved for ultrastructural analysis through high pressure freeze fixation and freeze substitution we describe the frequent occurrence of microfilament (MF)-endoplasmic reticulum (ER) complexes. These are found throughout the cytoplasm where they are observed in close association with the plasmalemma (PL), the tonoplast, nuclei, mitochondria, chloroplasts, and microbodies. The MF component of the complexes is identified as actin based on immunogold labelling with actin antibodies. The actin-ER complexes are prominent in the cortical cytoplasm. In this region a network of predominantly tubular ER occupies an intermediary position in which it associates closely with both the PL and the actin MFs. We suggest that the ER, especially those elements adjacent to the PL in the cortical cytoplasm, stabilizes the actin MFs and provides the necessary anchor against which the forces for cytoplasmic streaming are generated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322621
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  • 6
    Electronic Resource
    Electronic Resource
    Vesicle production and fusion during lobe formation inMicrasterias visualized by high-pressure freeze fixation (1992)
    Springer
    Protoplasma 170 (1992), S. 104-114 
    Details
    ISSN: 1615-6102
    Keywords: Dictyosomes ; Golgi vesicles ; Micrasterias ; Morphogenesis ; Vesicle fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two different types of Golgi vesicles involved in wall formation can be visualized during lobe growth inMicrasterias when using high-pressure freeze fixation followed by freeze substitution. One type that corresponds to the “dark vesicles” (DV) described in literature seems to arise by a developmental process occurring at the Golgi bodies with the single vesicles being forwarded from one cisterna to the next. The other vesicle type appears to be produced at thetrans Golgi network without any visible precursors at the Golgi cisternae. A third type of vesicle, produced by median andtrans cisternae, contains slime; these are considerably larger than those previously mentioned and they do not participate in wall formation. The distribution of the two types of cell wall vesicles at the cell periphery and their fusion with the plasma membrane are shown for the first time, since chemical fixation is too slow to preserve a sufficient number of vesicles in the cortical cytoplasm. The results indicate that fusions of both types of vesicles with the plasma membrane are possible all over the entire surface of the growing half cell. However, the DVs are much more concentrated at the growing lobes, where they form queues several vesicles deep behind zones on the plasma membrane thought to be specific fusion sites. The structural observations reveal that the regions of enhanced vesicle fusion correspond in general to the sites of calcium accumulation determined in earlier studies. By virtue of the absence of the DVs in the region of cell wall indentations the second type of wall forming vesicle appears prominent; they too fuse with the plasma membrane and discharge their contents to the wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378786
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  • 7
    Electronic Resource
    Electronic Resource
    Early development ofRhizobium-induced root nodules ofParasponia rigida. I. Infection and early nodule initiation (1984)
    Springer
    Protoplasma 123 (1984), S. 26-37 
    Details
    ISSN: 1615-6102
    Keywords: Infection ; Invasion ; Multicellular Root Hairs ; Parasponia ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The first of two major steps in the infection process in roots ofParasponia rigida (Ulmaceae) following inoculation byRhizobium strain RP501 involves the invasion ofRhizobium into the intercellular space system of the root cortex. The earliest sign of root nodule initiation is the presence of clumps of multicellular root hairs (MCRH), a response apparently unique amongRhizobium-root associations. At the same time or shortly after MCRH are first visible, cell divisions are initiated in the outer root cortex of the host plant, always subjacent to the MCRH. No infection threads were observed in root hairs or cortical cells in early stages. Rhizobial entry through the epidermis and into the root cortex was shown to occur via intercellular invasion at the bases of MCRH. The second major step in the infection process is the actual infectionper se of host cells by the rhizobia and formation of typical intracellular infection threads with host cell accommodation. This infection step is probably the beginning of the truly symbiotic relationship in these nodules. Rhizobial invasion and infection are accompanied by host cortical cell divisions which result in a callus-like mass of cortical cells. In addition to infection thread formation in some of these host cortical cells, another type of rhizobial proliferation was observed in which large accumulations of rhizobia in intercellular spaces are associated with host cell wall distortion, deposition of electron-dense material in the walls, and occasional deleterious effects on host cell cytoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283179
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructure of freeze-substituted pollen tubes ofLilium longiflorum (1992)
    Springer
    Protoplasma 167 (1992), S. 215-230 
    Details
    ISSN: 1615-6102
    Keywords: Lilium ; Freeze substitution ; Pollen tubes ; Rapid freeze fixation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In view of the importance of the lily pollen tube as an experimental model and the improvements in ultrastructural detail that can now be attained by the use of rapid freeze fixation and freeze substitution (RF-FS), we have reexamined the ultrastructure of these cells in material prepared by RF-FS. Several previously unreported details have been revealed: (1) the cytoplasm is organized into axial “slow” and “fast” lanes, each with a distinct structure; (2) long, straight microtubule (MT) and microfilament (MF) bundles occur in the cytoplasm of the fast lanes and are coaligned with every organelle present; (3) the cortical cytoplasm contains complexes of coaligned MTs, MFs, and endoplasmic reticulum (ER); (4) the cortical ER is arranged in a tight hexagonal pattern and individual elements are closely appressed to the plasma membrane with no space between; (5) mitochondria and ER extend into the extreme apex along the flanks of the pollen tube, and vesicles and ER are packed into an inverted cone-shaped area at the center of the apex; (6) MF bundles in the tip region are fewer, finer, and in random orientation in comparison to those of the fast lanes; (7) the generative cell (GC) cell wall complex contains patches of plasmodesmata; (8) The GC cytoplasm contains groups of spiny vesicles that are closely associated with and seem to be fusing with or pinching off from mitochondria, and (9) the vegetative nucleus (VN) contains internal MT-like structures as well as numerous cytoplasmic MTs associated with its membrane and also located between the VN and GC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01403385
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