In situ analysis of cell wall polymers associated with phloem fibre cells in stems of hemp, Cannabis sativa L.

Abstract The aim of this study was to determine the effect of removing extractives from the woody core of hemp (chènevotte) on the chain mobility of hemicelluloses and lignins, which can react during technological transformation such as de-fibering and/or composite materials production. Extractives are molecules with low molecular weight, which are present in the cell wall matrix and can be readily removed by solvents. In the present paper, the nature and amounts of extractives, removed under different conditions and with solvents of different polarities, were determined. The mobility and structural relaxations of lignins and hemicelluloses were stu-died in situ by dynamic mechanical analysis and dielectric analysis under controlled moisture content. Extractions at low temperature led to rigidification of lignins and plasticizing of hemicelluloses, probably due to local changes by the selective removal of molecules interacting with the polymers. Probably, the accessibility of hemicelluloses to plasticizing water was increased at controlled humidity. In contrast, hot extractions including water induced rigidification of the hemi-celluloses and plasticizing of lignins. This could be related to a combination of molecule extractions and chemical modi-fications of both polymers. This interpretation is supported by the variation of activation energy for relaxation of hemi-celluloses. It can be concluded that each type of extraction has a clear specific effect on the relaxation properties of the amorphous cell wall polymers.

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Bacterial surface antigen-specific monoclonal antibodies used to detect beer spoilage pediococci

Canadian Journal of Microbiology ◽

10.1139/w99-060 ◽

1999 ◽

Vol 45 (8) ◽

pp. 670-677 ◽

Cited By ~ 12

Author(s):

Michael S Whiting ◽

W M Ingledew ◽

Sun Y Lee ◽

Barry Ziola

Keyword(s):

Cell Wall ◽

Monoclonal Antibodies ◽

Surface Antigen ◽

Surface Antigens ◽

Bacterial Surface ◽

Cell Wall Polymers ◽

Good Potential ◽

Protease Treatment ◽

Beer Spoilage

Fourteen monoclonal antibodies (Mabs) were isolated that react with surface antigens of Pediococcus beer spoilage organisms, including P. damnosus, P. pentosaceous, P. acidilactici, and unspeciated isolates. Immunoblotting, enzyme immunoassays (EIAs) of protease- and neuraminidase-treated surface antigen extracts, carbohydrate competition EIAs, and cardiolipin EIAs were used to characterize the bacterial antigens involved in Mab binding. Antigen stability in situ was tested by protease treatment or surface antigen extraction of washed bacteria. In most cases, the Mabs bind to Pediococcus surface antigens that appear to be covalently bound cell wall polymers resistant to alteration or removal from the bacterial surface. These bacterial surface antigen reactive Mabs show good potential for rapid, sensitive, and specific immunoassay detection of Pediococcus beer spoilage organisms.Key words: beer spoilage organism, immunoassay, monoclonal antibodies, Pediococcus, surface antigens.

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In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100083035 ◽

1978 ◽

Vol 36 (2) ◽

pp. 434-435

Author(s):

D. Reis ◽

B. Vian ◽

J. C. Roland

Keyword(s):

Cell Wall ◽

Self Assembly ◽

Plant Cell Wall ◽

Higher Plants ◽

Three Dimensional ◽

Cytochemical Study ◽

Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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