The glucuronoxylans and the helicoidal shift in cellulose microfibrils in linden wood: Cytochemistryin muro and on isolated molecules

Autor: Michèle Mosiniak, Danièle Reis, Brigitte Vian, J. C. Roland
Rok vydání: 1986
Předmět:
Zdroj: Protoplasma. 131:185-199
ISSN: 1615-6102
0033-183X
DOI: 10.1007/bf01285040
Popis: In fibres of wood, the classical S1 and S2 layers are connectedvia a transition zone where a helicoidal texture occurs. In order to understand the actual mechanism of cellulose microfibril rotation in this zone, the study of relationship between cellulose and matrix was undertaken cytochemically at the ultrastructural level. Glucuronoxylans,i.e., the main hemicellulose component of hardwood, were studied in cell walls of linden tree. Xylanase-gold complexes were used as a new cytochemical tool to directly and specifically label glucuronoxylans within the wall of fibres. Subtractive localization (KOH or DMSO extraction and PATAg test or shadowing) associated with chemical analysis was carried out as control. The study of isolated glucuronoxylan molecules was undertaken in parallel. Both from direct (xylanase-gold labeling) and indirect techniques (extractions), glucuronoxylans appear preferentially concentrated in the transition zone which overlaps the layers S1 and S2. A comparison between KOH and DMSO extraction indicates a difference in accessibility of glucuronoxylans distributed across the whole wall and those located in the transition zone. Isolated molecules have a rodlike aspect and show a tendancy to spatially organize in parallel alignment. Cytochemical labeling of the isolated molecules concerns covalent linkages, vic-glycol groups and acid side groups along the main chain. The preferential localization indicates that in the helicoidal zone glucuronoxylans constitute a thick matrix embedding the cellulose microfibrils in the course of rotation. This data leads to a discussion of how these localized matrix molecules could intervene in the assembly and the twisted morphogenesis of the fibre cell wall.
Databáze: OpenAIRE
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