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  • 1980-1984  (4)
  • 1975-1979  (1)
  • 1970-1974
  • 1920-1924
  • Slow muscle fibres  (3)
  • Water permeability  (2)
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Years
  • 1980-1984  (4)
  • 1975-1979  (1)
  • 1970-1974
  • 1920-1924
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Fine structure of plant cuticles in relation to water permeability: The fine structure of the cuticle of Clivia miniata reg. leaves (1981)
    Springer
    Planta 152 (1981), S. 259-267 
    Details
    ISSN: 1432-2048
    Keywords: Clivia ; Cuticle development and fine structure ; Water permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fine structure of the upper cuticular membrane (CM) of Clivia miniata leaves was investigated using electron microscopy. The CM is made up of a thin (130 nm) lamellated cuticle proper (CP) and a thick (up to 7 μm over periclinal walls) cuticular layer (CL) of marbled appearance. Evidence is presented to show that the electron lucent lamellae of the CP do not simply represent layers of soluble cuticular lipids (SCL). Instead, the lamellation is probably due to layers of cutin differing in polarity. It is argued that the SCL in the Cp are the main barrier to water. Thickening of the CM during leaf development takes place by interposition of cutin between the CM and the cellin wall. The cutin of young, expanding leaves has a high affinity for KMnO4 and is therefore relatively polar. As leaves mature, the external CL underneath the CP becomes non-polar, as only little contrast can be obtained with permanganate as the post fixative.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385154
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Water permeability of periderm membranes isolated enzymatically from potato tubers (Solanum tuberosum L.) (1983)
    Springer
    Planta 158 (1983), S. 294-301 
    Details
    ISSN: 1432-2048
    Keywords: Periderm membranes ; Solanum, periderm ; Suberin ; Tuber ; Water permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fine structure and water permeability of potato tuber periderm have been studied. Periderm membranes (PM) were isolated enzymatically using pectinase and cellulase. They were composed of, about six layers of phellem cells arranged in radial rows. The walls of phellem cells consist of cellulosic primary and tertiary walls and suberized secondary walls which are lamellated. Middle lamellae and primary walls contain lignin. Since the PM did not disintegrate during enzymatic isolation it appears that lignin also extends into the secondary suberized walls. The water permeability of PM was low, ranging from 1–3·10-10 m s-1. This low water permeability developed only during storage of tubers in air. Periderm membranes from freshly harvested tubers had a relatively high permeability. The low permeability of PM from stored tubers is attributed to soluble lipids associated with suberin since: (1) extraction of soluble lipids from PM increased permeability by more than 100-fold, (2) a phase transition of soluble lipids was observed between 46 and 51° C, and (3) only the permeability of PM decreased during storage while the permeability of extracted PM remained unchanged. Evidence is presented that two pathways for water movement exist in parallel. Pathway 1 is represented by middle lamellae and primary walls extending in radial direction across the membranes. This pathway has a relatively high specific permeability. Pathway 2 is represented by a polylaminated structure made up of tangential walls of phellem cells which are orientated normal to the direction of water flow. This pathway has a low specific permeability because of the properties of secondary walls incrusted with soluble lipids. It is calculated that about 10% of the water flows across pathway 1 and 90% across pathway 2 which has a volume fraction of 0.995.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397330
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of nerve length and temperature on the induction of action potentials in denervated slow muscle fibres of the frog (1977)
    Springer
    Pflügers Archiv 372 (1977), S. 17-22 
    Details
    ISSN: 1432-2013
    Keywords: Slow muscle fibres ; Action potential ; Nerve stump ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A. Pyriformis and extensor longus digiti IV muscles of Rana temporaria were denervated by cutting the sciatic or peroneal nerve at various distances from the muscles. Slow fibres were identified by their membrane time constants, and examined for their ability to produce action potentials in response to intracellularly applied current pulses. B. The slow muscle fibres acquired the ability to generate action potentials several days after denervation. The duration of this latent period depended on the length of the peripheral nerve stump, and on the temperature at which the frogs were kept after the operation. C. At 18°C the latent period increased by 0.36 days per mm of sciatic nerve stump. At 11.5° C the corresponding value was 0.7 days/mm. The effect of length of the peroneal nerve was smaller than that of the sciatic nerve. D. It is suggested that the peripheral nerve stump serves as a reservoir of ‘trophic’ material which is transported towards the slow fibres at a rate of 2.8 mm/day (at 18° C) and seems to block the formation of Na channels. TheQ 10 value of this transport system would be 2.7.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582201
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Acetylcholine-sensitivity and local regenerative activity in denervated frog slow muscle fibres (1984)
    Springer
    Pflügers Archiv 402 (1984), S. 88-93 
    Details
    ISSN: 1432-2013
    Keywords: Slow muscle fibres ; Denervation ; ACh-sensitivity ; Local electrical activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 1. The distribution of acetylcholine (ACh)-sensitive membrane areas was determined in 11–75 days denervated slow muscle fibres ofRana temporaria by iontophoretic application of acetylcholine. The fibres were also stimulated directly, and their electrical activity was recorded with an intra- and an extracellular electrode. 2. During the first two weeks following denervation the size of the ACh-sensitive fibre surface was similar to that of normal slow fibres, but a spreading out of ACh-sensitivity occurred between the 13th and 20th day. 3. The slow fibre membrane did not become homogeneously ACh-sensitive; even after long periods of denervation large local sensitivity gradients could be observed. Throughout the denervation period maximum values of ACh-sensitivity were in the same range as in normal slow fibres. 4. Action potentials were fully developed when ACh-sensitivity started to spread out. Extracellularly recorded inward currents varied in amplitude along the fibre surface, and either one or two peaks were observed in individual fibres. 5. The spatial relationship between inward current peaks and peaks of ACh-sensitivity was investigated in 12 fibres. Fifteen inward current peaks were located at distances of 30–640 μm from points of maximum ACh-sensitivity; only once did the centers of ACh-sensitivity and excitability coincide. 6. It is concluded that Na channels are incorporated into nonjunctional membrane areas of denervated slow fibres; this process preceds the incorporation of ACh-receptors by approximately one week.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584836
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Distribution of acetylcholine-sensitivity in frog slow muscle fibres (1983)
    Springer
    Pflügers Archiv 397 (1983), S. 300-305 
    Details
    ISSN: 1432-2013
    Keywords: Slow muscle fibres ; ACh ; Sensitivity ; Distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 1) The distribution of acetylcholine-sensitive membrane areas in slow muscle fibres of pyriformis muscles of Rana temporaria was examined by iontophoretic application of acetylcholine from high resistance pipettes. 2) ACh-sensitivity varied considerably along individual slow fibres and from fibre to fibre. In some fibres the sensitivity was restricted to segments of less than 100 μm, in others it was continuous over several millimeter. Segments of variable length, but up to several millimeter, were completely insensitive to acetylcholine. Highly sensitive spots (〉1,000 mV/nC) were found occasionally, their diameter being of the order of 10–20 μm only. The occurrence at rather regular intervals of ACh-sensitive areas was a rare observation; no evidence was found for a generalized ACh-sensitivity. 3) There were marked differences in the lengths of ACh-sensitive segments between surface fibres and fibres located in deeper layers of the muscles. 4) It is concluded that the ACh-sensitive membrane areas correspond to individual nerve muscle contacts of the small motor system whose spatial distribution is extremely variable. In superficial slow fibres the synaptic contacts seem to be located predominantly on the internal circumference of the fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580265
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    Paper (German National Licenses)
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