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  • 1985-1989  (2)
  • 1986  (2)
  • Hordeum (enzymes)  (1)
  • Protoplasts  (1)
  • 1
    ISSN: 1432-2048
    Keywords: Aleurone (enzyme secretion) ; α-Amylase ; Gibberellin and enzyme secretion ; Hordeum (enzymes) ; Monensin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of monensin on the secretion of α-amylase and other enzymes from the aleurone layer of barley (Hordeum vulgare L. cv. Himalaya) was studied by electrophoresis followed by fluorography and by pulse-chase and organelle-isolation experiments. Monensin markedly inhibits the secretion, but not the synthesis, of α-amylase, acid phosphatase, and at least four other proteins from the aleurone layer. Monensin treatment causes α-amylase to accumulate within the protoplast, but its effect on the different α-amylase isoenzymes is not equal. The accumulation of isoenzyme 2 is not influenced by monensin while isoenzymes 1, 3 and 4 are not secreted but rather accumulate in the cell when monensin is included in the incubation medium. The α-amylase and acid-phosphatase activities which accumulate within the aleurone cells following treatment with monensin are localized in an organelle having a buoyant density greater than that of endoplasmic reticulum and less than that of mitochondria. In pulse-chase experiments with [35S]methionine, labelled proteins accumulate in this organelle in the presence of monensin and do not appear in the incubation medium. We conclude that monensin inhibits the secretion of proteins from the barley aleurone layer by influencing their intracellular transport.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1615-6102
    Keywords: Barley aleurone ; Fluorescein diacetate ; Propidium iodide ; Protoplasts ; Viability determination ; Vital stains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The utility of numerous dyes for determining the viability of barley (Hordeum vulgare L. cv. Himalaya) aleurone protoplasts was studied. Protoplasts isolated from the barley aleurone layer synthesize and secrete α-amylase isozymes in response to treatment with gibberellic acid (GA) and Ca2+. These cells also undergo dramatic morphological changes which eventually result in cell death. To monitor the viability of protoplasts during incubation in GA and Ca2+, several types of fluorescent and nonfluorescent dyes were tested. Evans blue and methylene blue were selected as nonfluorescent dyes. Living cells exclude Evans blue, but dead cells and cell debris stain blue. Both living and dead cells take up methylene blue, but living cells reduce the dye to its colorless form whereas dead cells and cell debris stain blue. The relatively low extinction coefficient of these dyes sometimes makes it difficult to distinguish blue-stained cells against a background of blue dye. Several types of fluorescent dyes were tested for their ability to differentially stain dead or living cells. Tinopal CBS-X, for example, stains only dead cells, and its high extinction coefficient allows its ultraviolet fluorescence to be recorded even when preparations are simultaneously illuminated with visible light. To double-stain protoplasts, the most effective stain was a combination of fluorescein diacetate (FDA) and propidium iodide (PI). By employing a double-exposure method to record the fluorescence from cells stained with both FDA and PI, dead and living cells could be distinguished on the basis of fluorochromasia.
    Type of Medium: Electronic Resource
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