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  • 1
    Electronic Resource
    Electronic Resource
    Automated pressure probe for measurement of water transport properties of higher plant cells (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2614-2619 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A computer-assisted instrument was constructed to measure the fundamental physical properties that regulate water transport at the cell level in plants. With this automated pressure probe, we measure a cell's hydrostatic pressure by inserting an oil-filled glass capillary into the cell. The capillary is connected to a pressure sensor and to a plunger controlled by a stepper motor. At the capillary tip an interface forms between the cell sap and oil. The image of this interface is directed through a microscope to a video camera. The interface position is detected by a video processor sampling at 60 Hz and is regulated by a microcomputer which advances or retracts the plunger at rates up to 280 steps per second. To determine the hydraulic conductance of cell membranes, the computer carries out pressure-relaxation and pressure-clamp experiments. Pressure is recorded with a resolution of 0.02 bar and is regulated in pressure-clamp experiments at ±0.02 bar. The instrument measures the cell volumetric elastic modulus by injecting or removing small volumes from the cell while simultaneously measuring cell turgor pressure. This system was tested on the cells of pea seedlings and proved superior to the previous techniques, especially for pressure-clamp experiments and volumetric elastic modulus determinations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139068
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  • 2
    Electronic Resource
    Electronic Resource
    The relationship between xyloglucan endotransglycosylase and in-vitro cell wall extension in cucumber hypocotyls (1993)
    Springer
    Planta 190 (1993), S. 327-331 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall (expansion, enzymes) ; Cucumis (cell wall expansion) ; Enzyme (cell wall) ; Protein (cell wall extension inducing) ; Xyloglucan endotransglycosylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It has been proposed that cell wall loosening during plant cell growth may be mediated by the endotransglycosylation of load-bearing polymers, specifically of xyloglucans, within the cell wall. A xyloglucan endotransglycosylase (XET) with such activity has recently been identified in several plant species. Two cell wall proteins capable of inducing the extension of plant cell walls have also recently been identified in cucumber hypocotyls. In this report we examine three questions: (1) Does XET induce the extension of isolated cell walls? (2) Do the extension-inducing proteins possess XET activity? (3) Is the activity of the extension-inducing proteins modulated by a xyloglucan nonasaccharide (Glc4-Xyl3-Gal2)? We found that the soluble proteins from growing cucumber (cucumis sativum L.) hypocotyls contained high XET activity but did not induce wall extension. Highly purified wall-protein fractions from the same tissue had high extension-inducing activity but little or no XET activity. The XET activity was higher at pH 5.5 than at pH 4.5, while extension activity showed the opposite sensitivity to pH. Reconstituted wall extension was unaffected by the presence of a xyloglucan nonasaccharide (Glc4-Xyl3-Gal2), an oligosaccharide previously shown to accelerate growth in pea stems and hypothesized to facilitate growth through an effect on XET-induced cell wall loosening. We conclude that XET activity alone is neither sufficient nor necessary for extension of isolated walls from cucumber hypocotyls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196961
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  • 3
    Electronic Resource
    Electronic Resource
    An oat coleoptile wall protein that induces wall extension in vitro and that is antigenically related to a similar protein from cucumber hypocotyls (1993)
    Springer
    Planta 191 (1993), S. 349-356 
    Details
    ISSN: 1432-2048
    Keywords: Acid growth ; Avena (coleoptile growth) ; Cell wall extension ; Expansin ; Protein (cell wall)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant cell walls expand considerably during cell enlargement, but the biochemical reactions leading to wall expansion are unknown. McQueen-Mason et al. (1992, Plant Cell 4, 1425) recently identified two proteins from cucumber (Cucumis sativus L.) that induced extension in walls isolated from dicotyledons, but were relatively ineffective on grass coleoptile walls. Here we report the identification and partial characterization of an oat (Avena sativa L.) coleoptile wall protein with similar properties. The oat protein has an apparent molecular mass of 29 kDa as revealed by sodium dodecyl sulfate-polyacrylamide gel eletrophoresis. Activity was optimal between pH 4.5 and 5.0, which makes it a suitable candidate for “acid growth” responses of plant cell walls. The oat protein induced extension in walls from oat coleoptiles, cucumber hypocotyls and pea (Pisum sativum L.) epicotyls and was specifically recognized by an antibody raised against the 29-kDa wall-extension-inducing protein from cucumber hypocotyls. Contrary to the situation in cucumber walls, the acid-extension response in heat-inactivated oat walls was only partially restored by oat or cucumber wall-extension proteins. Our results show that an antigenically conserved protein in the walls of cucumber and oat seedlings is able to mediate a form of acid-induced wall extension. This implies that dicotyledons and grasses share a common biochemical mechanism for at least part of acid-induced wall extensions, despite the significant differences in wall composition between these two classes of plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195692
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