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  • 1990-1994  (2)
  • 1955-1959
  • Immunocytochemistry  (1)
  • Ozone uptake  (1)
  • 1
    ISSN: 1432-2285
    Keywords: Ozone uptake ; Stomatal conductance ; Spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The uptake of air pollutants depends both on pollutant concentration and on stomatal conductance. This paper deals with the uptake of ozone (O3) from the air into the needles of Norway spruce [Picea abies (L.) Karst.] under ambient climatic conditions. Regulation of O3 uptake by the stomata is shown and also the difference between the “physiologically active O3 concentration” and the O3 concentration of the ambient air. Data from the sun and shade crown of spruce trees at 1000 m a.s.l. are presented. Analysis of data from three vegetation periods has shown that at low ambient O3 concentrations the O3 uptake is largely regulated by stomatal conductance. Water vapour pressure deficit (VPD) of the atmosphere is the climatic factor which showed the highest positive correlation with O3 concentration. However, a high leaf-air VDP led to stomatal closure, thus reducing the O3 uptake in the needles despite high O3 concentrations in the ambient air. The potential O3 stress caused by high O3 concentrations can be strongly mitigated by this natural closing of the stomata and the simultaneous occurrence of moderate drought stress.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 272 (1993), S. 183-192 
    ISSN: 1432-0878
    Keywords: Retina ; Müller cells ; Neuron-specific enolase ; Immunocytochemistry ; Quantitative analysis ; Ultrastructure ; Bufo marinus (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have previously shown that an antibody against neuron-specific enolase (NSE) selectively labels Müller cells (MCs) in the anuran retina (Wilhelm et al. 1992). In the present study the light- and electron-microscopic morphology of MCs and their distribution were described in the retina of the toad, Bufo marinus, using the above antibody. The somata of MCs were located in the proximal part of the inner nuclear layer and were interconnected with each other by their processes. The MCs were uniformly distributed across the retina with an average density of 1500 cells/mm2. Processes of MCs encircled the somata of photoreceptor cells isolating them from each other by glial sheath, except for those of the double cones. Some of the photoreceptor pedicles remained free of glial sheath. Electron-microscopic observations confirmed that MC processes provide an extensive scaffolding across the neural retina. At the outer border of the ganglion cell layer these processes formed a non-continuous sheath. The MC processes traversed through the ganglion cell layer and spread beneath it between the neuronal somata and the underlying optic axons. These processes formed a continuous inner limiting membrane separating the optic fibre layer from the vitreous tissue. Neither astrocytic nor oligodendrocytic elements were found in the optic fibre layer. The significance of the uniform MC distribution and the functional implications of the observed pattern of MC scaffolding are discussed.
    Type of Medium: Electronic Resource
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