Valonia cell walls

Highly crystalline 0-chitin is obtained from pogonophore tubes and the spines of certain diatoms, and is analogous in both crystallinity and morphology to the cellulose obtained from Valonia cell walls. Intensity data (10) were obtained for 61 observed non-meridional reflections for a specimen of dispersed (sonicated) crystallites of pogonophore tube (Oligobrachia... 

Zimmerman, U., Steudle, E. Lelkes, P.I. (1976). Turgor pressure regulation in Valonia utricularis. Effect of cell wall elasticity and auxin. Plant Physiology, 58, 608-13. 

Fibril arrangements in the cell wall of Valonia (12,000 X), (Electron micrograph from A. Frey-Wyssling and K. Miihlethaler, Ultrastructural Plant Cytology, Elsevier Science Publishers, Amsterdam, 1965, p. 298. Reprinted with permission from Elsevier Science Publishers.)... 

Cellulose is insoluble in water because of the high affinity of the polymer chains for one another. Its individual polymeric chains have molecular weights of 50,000 or greater. The molecular chains of cellulose interact in parallel bundles of about 2,000 chains. Each bundle constitutes a single microfibril. Many microfibrils arranged in parallel constitute a macrofibril, which can be seen under the light microscope. Figure 12.10 shows the inner cell walls of the plant Valonia the fibrils in the wall are almost pure cellulose. 

T ine structural studies on woody cell walls attacked by ectoenzymes of fungi in situ are numerous (cf. 1,2). In contrast, investigations on the selective degradation of cell walls by enzymes isolated from fungi are few. Jutte and Wardrop (3) attempted the use of crude commercial cellu-lase preparations to determine the degradation pattern of Valonia cellulose and beechwood fibers. Similar use of commercial preparations of enzymes was made by Reis and Roland (4) to evaluate the nature of diverse cell walls and to show the distribution of polysaccharides. An endo-/ -l,4-xylanase with specific xylanolytic activities was isolated from a commercial cellulase preparation using chromatographic methods and... 

Figure 6. Potential difference across cell wall in the (large) green photosynthesizing alga Valonia utricularis as a function of temperature. Note abrupt changes near 15° and 29°C. (From Drost-Hansen and Thorhaug, 1967).

Fig. 2.—Cellulose Microfibrils from Valonia macrophysa. (The purified cell-wall was mechanically dispersed in distilled water, dried, and shadowed. Note the tabular shape and the compound nature of the microfibrils.)...

Sample Preparation. Valonla cellulose was obtained from the cell walls of valonia maovophysa. The valonla cell walls were purified as follows. They were washed with water thoroughly, boiled in a 1% NaOH aquous solution for 4 hr, and washed well with water. Then they were immersed In 0.1% acetic acid to neutralize the trace of the alkali, washed with water, and dried. 

A prerequisite for this model of stmetural interconversion is the existence of arrays of parallel-packed chains in a single microfibril, the arrays being oriented in up and down directions. The occurrence of such an arrangement was demonstrated in the highly crystalline and well-organized cell-wall of Valonia. Cellulose microfibrils are statistically distributed in opposite polarities wifltin given arrays, where they are packed side by... 

Fig. 42. Dif action-contrast transmission electron microscopy of a fragment of Valonia ventricosa cell-wall cross-sectioned perpendicular to one of the main microfibrillar directions. The pictme is printed in reverse contrast, so that the cross-sectioned microfibrils appear as white squares. (See Color Plate 17.)...

Sugiyama I, Harada H., Fujiyoshi Y., and Uyeda N. 1985. Lattice images from ultrathin sections of cellulose microfibrils in the cell wall of Valonia macrophysa Rutz. Planta 166 161-168. 

Crystals of ivory nut D-mannan have been grown on microfibrils from Valonia sp. cellulose. These crystals were in the form of perpendicularly orientated lamellae with widths of ca. 10 A as revealed by electron microscopy. The structure has been designated a shish-kebab type structure. Precipitation of the D-mannan on beaten softwood pulp fragments also gave shish-kebab type structures, indicating that the cellulosic fibre cell wall is a good substrate for orientated crystallization of D-mannan. 

High-resolution images of cellulose I microcrystals [155] demonstrated the application of CM-AFM to the study of large biopolymers. Here, the 0.52 nm repeat along the chains of the cellulose from Valonia ventricosa (a dark-green balloon-Uke marine alga) was observed. AFM has also been used to study the polysaccharides present in wheat straw cell walls [156], where clear differences can be seen both before and after de-waxing. Cellulose appeared to form microfibrils which were orientated in one direction. These fibrils measured some 20 nm in diameter and are believed to contain as many as 60-80 cellulose molecular chains. 

J Blackwell, PD Vasko, JL Koenig. Infrared and Raman spectra of the cellulose from the cell wall of Valonia ventricosa. J Appl Phys 41 4375-4379,1970. 

Fig. 2.23. Outermost lamellae of the wall of the alga Valonia ventricosa. EM picture at X 25,000. (From R. D. Preston, The Molecular Architecture of Plant Cell Walls, Chapman Hall, London, 1952.)...

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