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Variations in the structure of neutral sugar chains in the pectic polysaccharides of morphologically different carrot calli and correlations with the size of cell clusters (1996)

Kikuchi, A. ; Edashige, Y. ; Ishii, T. ; [et al.]

Springer

Planta 198 (1996), S. 634-639

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ISSN: 1432-2048

Keywords: Callus ; Cell wall ; Daucus (cell walls) ; Morphogenesis ; Neutral sugar ; Pectin

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Carrot (Daucus carota L.) embryogenic callus (EC) loses its embryogenic competence and becomes nonembryogenic callus (NC) during long-term culture. With the loss of embryogenic competence, the cell clusters become smaller and the extent of intercellular attachments is reduced. Pectic fractions prepared from EC and NC were separated into two subfractions by gel filtration. A difference in sugar composition between EC and NC was found only in the high-molecular-mass (ca. 1300 kDa) subfraction, and the ratio of the amount of arabinose to that of galactose (Ara/Gal) was strongly and positively correlated with the size of cell clusters in several different cultures. From the results of sugar-composition and methylation analyses, and the results of treatment with exo-arabinanase, models of the neutral sugar chains of pectins from EC and NC are proposed. Both neutral sugar chains are composed of three regions. The basal region is composed of linearly linked arabinan 5-Araf〉 moieties in both types of callus. The middle galactan region is composed of 6-linked galactose, some of which branches at the 3 and 4 positions, and this region is larger and more frequently branched in NC than in EC. Finally, the terminal arabinan region is composed of 5-linked arabinose, branched at the 3 position, and the size of the terminal arabinan is larger in EC than in NC. The significance of the neutral sugar chains of pectins in the interaction of cell wall components and intercellular attachment is discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00262652

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Compatibility and tensile behavior of polypropylene/ethylene-propylene rubber blends (1995)

Nomura, T. ; Nishio, T. ; Fujii, T. ; [et al.]

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 35 (1995), S. 1261-1271

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ISSN: 0032-3888

Keywords: Chemistry ; Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: This study clarifies and quantifies factors which increase the ductility of a low-molecular-weight propylene homopolymer having an intrinsic viscosity of 0.89 dl/g. The tensile behavior of homopolymer/ethylene-propylene rubber (EPR) blends was studied from the viewpoint of the associated molecular structure of EPR and its compatibility with the homopolymer. When EPR is “dissolved” in a homopolymer, the glass transition temperature (Tg) of the amorphous phase of a homopolymer was found to shift to a lower temperature, with homopolymer/EPR compatibility being subsequently evaluated using this shift, i.e., Δtg. Results show two conditions are required to improve the ductility of the low-molecular weight propylene homopolymer: ΔTg must be ≥ 3°C and ≥ 30 wt% EPR must be blended with the homopolymer.

Additional Material: 18 Ill.