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  • 1
    Electronic Resource
    Electronic Resource
    Observations on the time course of wall development at the surface of isolated protoplasts (1978)
    Springer
    Planta 139 (1978), S. 85-91 
    Details
    ISSN: 1432-2048
    Keywords: Antirrhinum ; Cellulose ; Nicotiana ; Protoplasts ; Scanning microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The formation of cell wall fibres at the surface of isolated leaf protoplasts has been studied by scanning electron microscopy. Fibres are not formed on incubated protoplasts until a lag period has elapsed. This period is about 8 h for leaf protoplasts of Nicotiana tabacum and about 45 h for leaf protoplasts of Antirrhinum majus. In the case of Antirrhinum protoplasts the length of the lag period is dependent on the concentration of osmoticum present during the incubation period. If regenerating protoplasts are briefly treated with dilute cellulase, the newly formed wall is completely digested. Such protoplasts are capable of producing new fibres at the surface within minutes of their return to a nutrient medium. These results are discussed in terms of the likely source of the lag period and its significance in wall regeneration studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390815
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cell-wall differentiation during growth of electrically polarised protoplasts of Physcomitrella (1982)
    Springer
    Planta 156 (1982), S. 241-248 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall (fine structure) ; Electric fields ; Physcomitrella ; Polarity ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts of Physcomitrella patens have been grown in continuous electric field of 50 V cm-1, resulting in a predictable pattern of filament emergence. The events preceding the visible formation of a polar axis have been examined by electron microscopy. The first sign of polarity is the formation of a thickened inner wall layer over the potential growth site. Elongation of the filament is preceded by the appearance of a layer of heavily stained amorphous material at the external surface of the thickened wall. This material marks the region of initial extension of the filament, but it is not produced once extension has begun, and further growth of the filament results in the retention of the material as an annular ring at its base. The wall of the filament has a complex thickened structure which is a result of the osmotic conditions under which the protoplasts are grown. These results are discussed in terms of the development of the polar axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393731
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Membrane mobility and the Concanavalin A binding system of the plasmalemma of higher plant protoplasts (1977)
    Springer
    Planta 136 (1977), S. 253-259 
    Details
    ISSN: 1432-2048
    Keywords: Concanavalin A ; Plasmalemma ; Protoplasts ; Scanning Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The binding of a colloidal gold-Concanavalin A (ConA) complex to the plasmalemma of tobacco leaf protoplasts has been investigated using scanning electron microscopy. At 5° C the particles of gold-ConA appear to be randomly distributed over the surface of the protoplast. If the temperature is raised, the particles associate into clusters. Saturation of the membrane with particles can only occur when the weight of ConA in solution exceeds 1 μg/104 protoplasts in suspension, and when its concentration exceeds 15 μg/ml. These results are discussed in terms of the properties of the ConA binding site and the mobility of such sites within the membrane surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385993
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Structure and association of wall fibrils produced by regenerating tobacco protoplasts (1979)
    Springer
    Planta 146 (1979), S. 203-210 
    Details
    ISSN: 1432-2048
    Keywords: Cellulose ; Microfibrils ; Negative staining ; Nicotiana ; Protoplasts ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study has been made of the wall fibrils produced by tobacco protoplasts, using scanning electron microscopy in conjunction with negative staining. It has been shown that the fibres seen in scanning electron microscopy correspond to aggregates of microfibrils. These aggregates are only visible where they are lifted clear of the protoplast surface. Negative staining of fixed protoplasts shows that the aggregation of microfibrils into the fibres visible in scanning electron microscopy is probably produced by air-drying. Gentle disruption of microfibrils produces both random broken fragments and bundles of short pieces of fibrillar material about 60 nm in length. This material is present in undisrupted young walls, but not in undisrupted older walls. The microfibrils in young walls seem much more fragile and liable to breakage than those in older walls. These results are discussed in terms of the interpretation of scanning electron microscope images and the mechanism of cellulose microfibril formation by higher plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388233
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Studies on the growth and development of protoplasts of the moss, Physcomitrella patens, and its control by light (1981)
    Springer
    Planta 151 (1981), S. 331-338 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall ; Microtubules ; Physcomitrella ; Polarity ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts prepared from protonemal cultures of the moss Physcomitrella patens begin to regenerate a new cell wall within 1 h of removal from cellulase. The wall is seen as a gradually thickening mat of fibres when examined by scanning electron microscopy. Development of filaments from protoplasts takes place in the majority of cases only after one or more cell divisions have occurred. The direction of emergence of filaments is random in uniform light, but strongly negatively phototropic in bright unidirectional horizotal light. Filament growth is also strongly negatively phototropic. The influence of unidirectional light can be destroyed by incubating protoplasts in the presence of colchicine. Filaments growing in unidirectional light have cytoplasmic microtubules running along their long axes and in close association with large organelles. These results are discussed in terms of the potential for this system for the study of polarity in plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393287
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Coumarin inhibition of microfibril formation at the surface of cultured protoplasts (1977)
    Springer
    Planta 133 (1977), S. 267-273 
    Details
    ISSN: 1432-2048
    Keywords: Cellulose Coumarin ; Microfibrils ; Plasmalemma ; Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of including coumarin in the culture medium of isolated tobacco leaf protoplasts has been studied by scanning microscopy. Fibre formation is completely suppressed for 48 h in concentrations of 200 and 250 mg/l of coumarin. Continuous culture in these concentrations of coumarin does not result in cell division or colony formation, although an atypical wall is visible after 4 days. The effect of coumarin is reversible. Viability of protoplasts exposed for 48 h to 200 mg/l coumarin is unaffected in terms of plating efficiency and infectability with virus. These results are discussed in relation to cell wall synthesis and the possible use of coumarin in prolonging the protoplast state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380688
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Studies of the recovery of tobacco mesophyll protoplasts from an evacuolation treatment (1985)
    Springer
    Protoplasma 126 (1985), S. 140-146 
    Details
    ISSN: 1615-6102
    Keywords: Electron microscopy ; Evacuolation ; Protoplasts ; Tobacco ; Vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mesophyll protoplasts ofNicotiana tabacum cv. Xanthi were subjected to centrifugation through a Percoll gradient. This resulted in the removal of the central vacuole from each protoplast, and improved mechanical and osmotic stability. Electron microscope studies showed that the remaining cell contents, including small vacuoles, were of normal morphology. Fixation of protoplasts at various times during subsequent culture showed that the central vacuole was restored after about 12 hours. Cell-wall formation was well advanced after 24 hours of culture. These results are discussed in terms of the potential use of evacuolate protoplasts and the mechanisms of vacuole formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01287680
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    Paper (German National Licenses)
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