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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 4 (1981), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Sites of acid-phosphatase activity were found in the differentiating root protophloem of Nymphoides peltata by lead-salt and by azo-dye methods. Different substrates revealed different subcellular locations of the enzyme. The substrates β-glycerophosphate (β-GP) and naphthol ASBI phosphate revealed enzyme activity at similar sites within the sieve element. These sites included plasmodesmata, dictyosomes and small vacuoles in the cytoplasm. The substrate p-nitrophenylphosphate (p-NPP), however, revealed additional sites of acid-phosphatase activity which were not detectable by either naphthol ASBI phosphate or β-GP. For example, the inner region of the wall in mature sieve elements showed conspicuous acid-phosphatase activity only when p-NPP was used as substrate. The significance of the different locations of acid phosphatase within the sieve element is discussed.The convoluted ER, characteristic of immature sieve elements of N. peltata, failed to show acid-phosphatase activity whichever substate was used. By contrast, the stacked ER found in the parietal layer of mature sieve elements showed prominent acid-phosphatase activity regardless of the substrate used. The demonstration of acid-phosphatase activity in the stacked ER, and by both lead-salt and azo-dye methods, suggests that this organelle is a true site of acid-phosphatase activity.The onset of acid-phosphatase activity in the ER in later stages of sieve-element differentiation is compatible with the view that stacked ER plays a role in the final autolysis of the sieve-element protoplast.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science, Ltd
    Plant, cell & environment 26 (2003), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 17 (1994), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: During plasmolysis of onion epidermal cells, the contracting protoplast remains connected to the cell wall by an intricate, branched system of plasma membrane (PM) ‘Hechtian strands’ which stain strongly with the fluorescent probe DiOC6. In addition, extensive regions of the cortical endoplasmic reticulum (ER) network remain anchored to the cell wall during plasmolysis and do not become incorporated into the contracting protoplast with the other cell organelles. These ER profiles become tightly encased by the PM as the latter contracts towards the centre of the cell. Thus, although the cortical ER is left outside the main protoplast body, it is nonetheless still bound by the PM of the cell. As well as being anchored to the wall, the cortical ER remains intimately linked with plasmodesmata and retains continuity between cells via the central desmotubules which become distended during plasmolysis. The PM also remains in close contact with the plasmodesmatal pore following plasmolysis. It is suggested that plasmodesmata, although sealed, may not be broken during plasmolysis, their substructure being preserved by continuity of both ER and PM through the plasmodesmatal pore. A structural model is presented which links the behaviour of PM, ER and plasmodesmata during plasmolysis.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 10 (1987), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract An experimental system has been developed for studying efflux of 14C assimilates in growing potato tubers. Small wells are cut into the phloem-rich perimedulla and filled with trap solutions of varying composition which inhibit or promote assimilate efflux. One well on each tuber acts as the treatment while a second well acts as the control. Movement of 14C into wells occurred at comparable rates to that found in intact tissue, harvested from importing tubers in the form of microcores. Sucrose was the predominant translocated sugar in the stolon and was not hydrolysed in either the wells or the microcores following unloading. Efflux into wells containing agar traps was stimulated 40-fold relative to buffer controls by the addition of 20 mol m−3 EGTA to the agar. This was interpreted as passive efflux to the apoplast due to increased membrane permeability in the pathway between the sieve elements and the collecting wells. The EGTA stimulation was reversed by addition of Ca2+. 14C efflux into buffered solutions was inhibited significantly by both DNP and PCMBS, suggesting the involvement of active and carrier-mediated transport components. However, it was not possible to determine whether these compounds acted at the site of unloading only, or on the short-distance transfer step between phloem and collecting wells. The rate of tracer efflux was not significantly different when 1 mol m−3 and 300 mol m−3 sucrose were applied to the wells, indicating insensitivity of solute movement to low apoplastic solute concentrations. However, raising the solute concentration to 800 mol m−3 caused a severe inhibition of tracer efflux. These results were duplicated with mannitol as the osmoticum. It is suggested that plasmolysis prevented further efflux by disruption of a predominantly symplastic transport pathway between the phloem and collecting wells.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 6 (1983), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The movement of fluorescein, a symplastic fluorescent tracer, into isolated caryopses of wheat and barley is described. The dye followed the pathway to the endosperm which has been proposed previously from anatomical studies, namely a movement from the phloem, through cells of the pigment strand and nucellar projection, followed by a radial spread of the dye from the endosperm cavity into the starchy endosperm. By contrast, the fluorochromes calcofluor white M2R and ANS remained confined to the apoplast and failed to cross the ‘xylem discontinuity’ at the base of the caryopses.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 4 (1981), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Mitochondria were found to be aligned along the upper periclinal walls of aleurone and endosperm cells in developing rice caryopses. The significance of this distribution is discussed in relation to previous studies of solute transport in rice.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 5 (1982), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Acid phosphatase was found cytochemically in intercellular spaces in the root of Nymphoides peltata. Different methods, using lead salts and azo-dyes, gave similar results. Reaction product appeared on material, possibly cytoplasmic, within the intercellular spaces and also against the outer walls of cells which formed the intercellular spaces. Possible functions of acid phosphatase in intercellular spaces are discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 5 (1982), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The fluorescent probe 8-anilino-l-naphthalene sulphonic acid (ANS) has been evaluated as a histochemical stain for plant tissues. The wide specificity of the compound for hydrophobic binding sites limits its analytical use, but renders it of considerable value as a general fluorescent stain for use in epi-illumination fluorescence microscopy. Used in this way it is analogous to the light-microscope stain toluidine blue. ANS has also been found to be a sensitive vascular tracer.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Planta 156 (1982), S. 461-465 
    ISSN: 1432-2048
    Keywords: Apoplast ; Hordeum (plasmatubules) ; Plasmalemmasome ; Plasmatubule ; Symplast ; Transfer cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tubular evaginations of the plasmalemma of the scutellar epithelial cells of barley are described. The evaginations are similar to those present at other sites where solute flux occurs for a limited period only and wall development of the transfer-cell form has not occured. Differential uptake of the fluorescent dyes fluorescein, which moves into the symplast, and 8-anilino-1-naphthalene sulphonic acid, which remains in the apoplast only, indicates that the scutellar epithelial cells contain the boundary between the apoplast and symplast. We suggest that i) the plasmalemma evaginations, which have a specific form and localisation, may be referred to as plasmatubules rather than by the general term plasmalemmasome, and that ii) the plasmatubules may act in membrane amplification in a short-term structural modification which is an alternative to transfer cells.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Planta 180 (1990), S. 555-561 
    ISSN: 1432-2048
    Keywords: Allium ; Apoplast ; Endocytosis (fluidphase) ; Epidermis ; Plasmolysis/deplasmolysis ; Vesicle (endocytic)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A transient plasmolysis/deplasmolysis (plasmolytic cycle) of onion epidermal cells has been shown to induce the formation of fluid-phase endocytic vesicles. Plasmolysis in the presence of the membrane-impermeant fluorescent probes Lucifer Yellow CH (LYCH) and Cascade Blue hydrazide resulted in the uptake of these probes by fluid-phase endocytosis. Following deplasmolysis, many of the dye-containing vesicles left their parietal positions within the cell and underwent vigorous streaming in the cytoplasm. Vesicles were observed to move within transvacuolar strands and their movements were recorded over several hours by video-microscopy. Within 2 h of deplasmolysis several of the larger endocytic vesicles had clustered around the nuclear membrane, apparently lodged in the narrow zone of cytoplams surrounding the nucleus. In further experiments LYCH was endocytically loaded into the cells during the first plasmolytic cycle and Cascade Blue subsequently loaded during a second plasmolytic cycle. This resulted in the introduction of two populations of endocytic vesicles into the cells, each containing a different probe. Both sets of vesicles underwent cytoplasmic streaming. The data are discussed in the light of previous observations of fluid-phase endocytosis in plant cells.
    Type of Medium: Electronic Resource
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