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  • 1
    Electronic Resource
    Electronic Resource
    Variation in stomatal aperture in leaves of Avena fatua L. observed by low-temperature scanning electron microscopy (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 12 (1989), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. A novel technique to record the variability of stomatal aperture over the leaf surface is described. This combines observations of leaf surfaces using low-temperature scanning electron microscopy (LTSEM), with digital image analysis to produce the most accurate aperture measurements obtained to date. Leaf samples are rapidly immobilized by cryo-fixation in liquid nitrogen and stored in a purpose-built cryo-storage system. Specimens can be collected in the field, remote from the cryopreparation system, and stored for up to several weeks before being examined on the LTSEM. The advantages of this method are that the time frame of the measurements is accurately known, and is identical for all stomatal apertures in a sample, and the precision of the measurements is not limited by the resolving power of the microscope. Measurements of stomatal aperture were obtained from leaves of field grown Avena fatua using the above procedure. Leaf surface conductance (gsur) was determined by porometry immediately before cryo-fixation of the same region of the leaf. Measurements of aperture size showed a high degree of variability within each specimen, with coefficients of variation similar to those found in previous studies. Stomatal conductance (gs) was calculated from stomatal dimensions using formulae derived elsewhere. A linear regression between the computed values of gs and porometric estimates of gsur showed good agreement with the regression line passing through the origin with a slope of 1.0 (R2=0.96). Applications of the experimental system are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1989.tb01968.x
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of polishing and abrasion on the diffusive conductance of leaf surface of Festuca arundinacea Schreb. (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 9 (1986), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Leaf surfaces of Festuca arundinacea Schreb. were subjected to controlled polishing and abrasion on a test-bed designed to simulate components of abrasive wind damage. Both treatments substantially increased the leaf surface conductance, particularly the polishing treatment. Scanning electron micrographs of cryo-fixed leaf surfaces showed displacement and smoothing of the epicuticular waxes, damage to the cuticle, collapse of epidermal cells and fracture of trichomes. The importance of the epicuticular waxes in determining leaf diffusivity and permeability is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1365-3040.ep11611633
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Water droplets and ice deposits in leaf intercellular spaces: redistribution of water during cryofixation for scanning electron microscopy (1987)
    Springer
    Planta 172 (1987), S. 20-37 
    Details
    ISSN: 1432-2048
    Keywords: Cell surfaces ; Cryofixation ; Freezing (extracellular, intracellular) ; Ice deposit (leaf) ; Intercellular space ; Leaf (water, ice) ; Phaseolus (leaf, cryofixation) ; Water droplet (artefacts, leaf)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An experimental study is described of the formation of extracellular deposits on the surfaces of cells in freeze-fractured, frozen-hydrated primary leaves of Phaseolus vulgaris examined by low-temperature scanning electron microscopy. The deposits, observed under a range of experimental conditions, consisted of (a) droplets with diameters of 1.5 to 3.0 μm, (b) droplets with diameters of 10 to 30 μm, (c) crystals with diameters of 1.0 to 6.0 μm, and (d) granules with diameters up to 0.15 μm. The types of deposit were influenced by specimen cooling rate, and their distribution was influenced by the direction of the thermal gradient during cooling. All deposits were predominantly water ice. The quantities of deposited water (up to 4.0% of the leaf water content) increased as the cooling rate was reduced. It is concluded that the ice deposits were primarily artefacts of cryofixation and do not represent the location of water in vivo, as recently suggested. We propose that the deposits arose in four main ways: (1) displacement of water from underlying cells by a pressure wave resulting from the volume increase of intracellular water as it freezes, (2) evaporation of water from warmer cells and its condensation onto colder cells, (3) withdrawal of water from underlying cells by extracellular ice crystallization, (4) condensation of pre-existing water vapour in the intercellular spaces onto cells. The significance of the findings is discussed in relation to the use of lowtemperature scanning electron microscopy in studies of plant morphology and for localizing water and soluble ions within plant cells and tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403025
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  • 4
    Electronic Resource
    Electronic Resource
    The genesis of intercellular spaces in developing leaves ofPhaseolus vulgaris L. (1986)
    Springer
    Protoplasma 132 (1986), S. 90-98 
    Details
    ISSN: 1615-6102
    Keywords: Phaseolus vulgaris ; Intercellular spaces ; Leaves ; Cellulolysis ; Cell wall ; Cryo scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Observations by light, transmission electron and scanning electron microscopy have shown that intercellular spaces (ICS) are formed schizogenously in expanding leaves ofPhaseolus vulgaris. ICS formation occurs in predictable positions at the junctions between three or more cells, and follows three phases of development. The first, initiation, phase occurs soon after cell division, and is marked by the formation of an electron-dense osmiophilic body, probably proteinaceous, at the end of the cell plate/middle lamella of the daughter cell wall and across the adjacent piece of the primary wall of the mother cell. This part of the mother cell wall is digested, involving cellulolysis. The second phase, of cell separation, is marked by the first appearance of the ICS. InPhaseolus primary leaves this phase begins about day 3 after sowing, at which time the leaf area is about 1 cm2. In the final enlargement phase, lysis of cell wall material continues in the region of the middle lamella, and mechanical tensions arising from the rapid expansion of the lamina lead to further separation of the mesophyll cells so that spaces enlarge and merge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275795
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    Paper (German National Licenses)
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