Differentiating sieve elements

Polymorphic behaviour seems also to be present in differentiating sieve elements of Acer [35], although continuity of the membrane across the... 

Figure 7.6 The cubic membrane system of differentiating sieve elements, showing the occurrence of a P- (a) and a G-PCS (b) in the same ceU. The section of the P-PCS has not been identified, while the lower right in (b) is a projection close to the [111] direction of the G-PCS. See text for further details, (c) A gyroid cubic membrane projected along the [211] direction.

A well-developed gyroid membrane can also be identified in the differentiating sieve elements of Nymphoides peltata investigated in [40], in which planes cut approximately normal to the 211 plane are evident (Fig. 7.6(c)). These and similar sections of the gyroid (see [57] for another example) are sometimes very difficult to assign, and can be confused with certain sections of the P-PCS structure. We have found it particularly important to investigate the influence of section thickness to avoid any confusion. 

Postulated as xylogenic factor during induction of 114 wound vessel differentiation in Coleus Transfer cells in sieve elements of legumes 109... 

Plants often synthesize and store active phytochemicals in specific organs. For example, glandular trichomes on the surface of leaves and stems in a variety of plants provide a major site for phytochemical synthesis, storage and secretion [10]. These differentiated organs express genes of various secondary metabolic pathways, as well as proteins associated with defence responses (e.g., superoxide dismutase in tobacco leaves] [10] or sulfur metabolism in [11]). The biosynthesis of various benzylisoqui-noline-derived alkaloids in opium poppy occurs in specific cells localized in sieve elements, whereas the final products accumulate in specialized... 

Tphe breakthrough curve for a fixed-bed adsorption column may be pre-dieted theoretically from the solution of the appropriate mass-transfer rate equation subject to the boundary conditions imposed by the differential fluid phase mass balance for an element of the column. For molecular sieve adsorbents this problem is complicated by the nonlinearity of the equilibrium isotherm which leads to nonlinearities both in the differential equations and in the boundary conditions. This paper summarizes the principal conclusions reached from a recent numerical solution of this problem (1). The approximations involved in the analysis are realistic for many practical systems, and the validity of the theory is confirmed by comparison with experiment. 

Considering a mass balance across a differential element in the froth of a sieve tray (Figure 12.57), the expressions for the vapor and liquid phase mass transfer units are... 

Aloni R (1980) Role of auxin and sucrose in the differentiation of sieve and tracheary elements in plant tissue cultures. Planta 150 255-263 Aloni R, Jacobs WP (1977 a) Polarity of tracheary regeneration in young internodes of Coleus (Labiatae). Am J Bot 64 395-403... 

Jacobs WP (1970) Regeneration and differentiation of sieve-tube elements. Int Rev Cytol 28 239-273... 

For the vapor passing through the liquid on the tray, the vapor concentration is changing from y-y to yont and should be calculated by differential method. Take a differential element Ah on the sieve tray as shown in Fig. 4.28, we have... 

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