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Results for “Pectins/metabolism”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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3 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Structural polarity in the Chara rhizoid: a reevaluation

The Chara rhizoid is a useful model system to study gravitropism since all phases of gravitropism occur in a single cell. Despite years of study, a complete description of the distinctive ultrastructure of Chara rhizoids is not available. Therefore, in this paper, we reevaluate the ultrastructural features of vertically grown rhizoids, which have a structural polarity consisting of seven distinct zones. We also characterize the apical vesicles and the cell wall in these rhizoids by using antibodies against pectic polysaccharides. These studies demonstrate that the cell wall consists of two pectinaceous domains and that a distinct population of apical vesicles contain methyl esterified pectin.

NASA Program Space Biology Research Associates↗
NASA NTRS1999

Polymer mobility in cell walls of cucumber hypocotyls

Cell walls were prepared from the growing region of cucumber (Cucumis sativus) hypocotyls and examined by solid-state 13C NMR spectroscopy, in both enzymically active and inactivated states. The rigidity of individual polymer segments within the hydrated cell walls was assessed from the proton magnetic relaxation parameter, T2, and from the kinetics of cross-polarisation from 1H to 13C. The microfibrils, including most of the xyloglucan in the cell wall, as well as cellulose, behaved as very rigid solids. A minor xyloglucan fraction, which may correspond to cross-links between microfibrils, shared a lower level of rigidity with some of the pectic galacturonan. Other pectins, including most of the galactan side-chain residues of rhamnogalacturonan I, were much more mobile and behaved in a manner intermediate between the solid and liquid states. The only difference observed between the enzymically active and inactive cell walls, was the loss of a highly mobile, methyl-esterified galacturonan fraction, as the result of pectinesterase activity.

NASA Discipline Plant Biology↗
NASA NTRS1978

Effects of experimental hypogravity on peroxidase and cell wall constituents in the dwarf marigold

Dwarf Marigolds grown from seed under experimental hypogravity are modified in lignin content, hemicellulose composition, and peroxidase activity. The two conditions used, clinostats and flotation, induced changes differing in magnitude but qualitatively similar. Most responses on clinostats required corrections for vertical axis rotational effects, thus limiting the value of these instruments in free-fall simulation. These findings extend earlier observations suggesting that increased peroxidase and decreased lignin are characteristic of growth under experimental hypogravity.

Cell Wall/metabolism↗