Patterns of polysaccharide biosynthesis in differentiating cells of maize root-tips

Abstract

1. The patterns of incorporation of radioactivity from d-[6-(3)H]-, d-[1-(14)C]-, d-[U-(14)C]- and d-[6-(14)C]-glucose and [U-(14)C]myoinositol into the neutral sugars and uronic acids of the polysaccharides synthesized in different regions of the root-tip of maize were determined. 2. The root-cap tissue synthesized a slime in which a polysaccharide that contained a high proportion of fucose (32%) and galactose (21%) was found. This polysaccharide is synthesized only by the root-cap cells, and very little polysaccharide containing fucose is synthesized in adjacent tissues. Part of the meristematic tissue of the root is surrounded by the cap cells. A section of the root that contains both these tissues can be analysed, and the polysaccharide synthesized by the meristematic region can be obtained since the contribution of the root-cap cells can be found by the amount of fucose formed. 3. It was shown that there is very little difference in the polysaccharide synthesis of the meristematic region from that of the cells immediately behind it. In the more mature cells, however, the amount of xylose synthesized relative to that of arabinose is increased, and the proportion of xylose and arabinose formed in the matrix polysaccharides is increased whereas that of galactose is decreased. 4. The effect of 2,4-dichlorophenoxyacetic acid (2,4-D) on polysaccharide synthesis was to bring about a decrease in the relative amount of galactose synthesized in the matrix polysaccharides of cells immediately adjacent to the meristematic region and also in the more mature tissue. The growth factor also increased the amount of xylose synthesized relative to that of arabinose in the more mature tissue. These metabolic effects were related to a very obvious change in the morphological appearance of the root-tips. 5. Radioactivity from [U-(14)C]myoinositol was incorporated mainly into xylose, arabinose and galacturonic acid rather than into the hexoses, although small amounts of these sugars were formed.

A Histochemical Study of Polysaccharide Distribution in Eucalypt Mycorrhizas

“…The staining properties of the extracellular material in Eucalyptus fastigata are identical to those of the Zea mays root cap polysaccharide: both are metachromatic with Toluidine Blue and both are weakly PAS-positive. Z. mays root cap slime has been collected and analysed, and the hydrolysate shown to contain a range of neutral sugars: predominantly galactose, glucose and fucose, with traces of glucuronic and galacturonic acid (see Harris and Northcote, 1970). The staining characteristics of Eucalyptus fastigata root cap polysaccharide suggest that it too contains uronic acid residues.…”

(1,3)‐β‐d‐Glucan Synthase from Budding and Filamentous Cultures of the Dimorphic Fungus Candida albicans

“…Spots were detected using alkaline silver nitrate [20]. Radioactively labelled material was located as described by Harris and Northcote [21]. Samples of radioactively labelled a-( 1,4)-linked glucan, prepared using enzymes from C. albicans [22], were also treated by these procedures.…”

Sur l'expression ultrastructurale de la differenciation des cellules vegetales.

“…1961, Northcote et Pickett-Heaps 1966, Juniper et Roberts 1966. Dauwalder et al 1966, 1969, Harris et Northcote 1970, Rougier 1971, Goff 1973, Dexheimer et al 1978.…”