Branching apical

The Boehmeria nivea is a dicot and angiosperm, is adapted to moist tropical climates and deep soils, is a perennial plant, occupies the land all year round and, when under cultivation, it is without branches (apical dominance, apical buds pinched off). 

Oae found that for both base- and acid-catalyzed hydrolysis of phenyl benzenesul-fonate, there was no incorporation of 0 from solvent into the sulfonate ester after partial hydrolysis. This was interpreted as ruling out a stepwise mechanism, but in fact it could be stepwise with slow pseudorotation. In fact this nonexchange can be explained by Westheimer s rules for pseudorotation, assuming the same rules apply to pentacoordinate sulfur. For the acid-catalyzed reaction, the likely intermediate would be 8 for which pseudorotation would be disfavored because it would put a carbon at an apical position. Further protonation to the cationic intermediate is unlikely even in lOM HCl (the medium for Oae s experiments) because of the high acidity of this species a Branch and Calvin calculation (See Appendix), supplemented by allowance for the effect of the phenyl groups (taken as the difference in between sulfuric acid and benzenesulfonic acid ), leads to a pA, of -7 for the first pisTa of this cation about -2 for the second p/sTa. and about 3 for the third Thus, protonation by aqueous HCl to give the neutral intermediate is likely but further protonation to give cation 9 would be very unlikely. 

Numbers used in this cycle AG° for hydroxide plus monomethyl sulfate, assumed to be the same as for dimethyl sulfate estimated above AG° for ionization of monomethyl sulfate AG° for tautomerization of the anionic adduct, based on pK values estimated by the method of Branch and Calvin AG° for ionization of the apically protonated adduct, based on a pK estimated by the method of Branch and Calvin.)... 

Preparation of hydrilla explants. A stainless steel razor was used to remove the distal 4 to 5 cm ("apical explants") from either rooted hydrilla, or hydrilla freshly received from the field. Subtending sections containing two adjacent intact nodes ("2-node explants") with whole whorls of leaves were removed, but 1 to 2 intervening nodes were left above the next cut (Figure 2). No 2-node explants were taken below (proximal to) a subtending lateral branch. All explants were kept in tap water for 2 4 hours in a growth chamber before use in bioassays (25°C, 14-h day, ca. 200 pE m-2 sec-1). 

Figure 11.1 Ultrastructure of the human lung alveolar barrier. The tissue specimen is obtained via lung resection surgery. (A) Section through a septal wall of an alveolus. The wall is lined by a thin cellular layer formed by alveolar epithelial type I cells (ATI). Connective tissues (ct) separate ATI cells from the capillary endothelium (en) within which an erythrocyte (er) and granulocyte (gc) can be seen. The minimal distance between the alveolar airspace (ai) and erythrocyte is about 800-900 nm. The endothelial nucleus is denoted as n. (B) Details of the lung alveolar epithelial and endothelial barriers. Numerous caveolae (arrows) are seen in the apical and basal plasma membranes of an ATI cell as well as endothelial cell (en) membranes. Caveolae may partake transport of some solutes (e.g., albumin). (C) ATII cells (ATII) are often localised in the comers of alveoli where septal walls branch off. (D) ATII cells are characterised by numerous multilamellar bodies (mlb) which contain components of surfactant. A mitochondrion is denoted as mi.

Sporangia consisting of transformed apical portions of short branches.Order Sphacelariales... 

Figure 2 shows the effect of the inoculated root tip part on the growth of P. ginseng hairy roots. The end part, whose apical meristem of root tip had been excised prior to inoculation, was grown to a total biomass 1.6 times greater than that of the center parts, which are the root tip part after being excised about 10 mm from the end part. In all experiments, new lateral branch formation was observed on the inoculated main root tip. 

The root tip with apical meristem showed length enhancement with lateral root formation. However, the center root tip formed lateral roots without length enhancement of the original root tip (Fig. 3). Some researchers have reported the effect of the apical dominance on growth, which was observed as an increase in specific growth rate for inocula formed by branched roots (12,14). 

Some suggest the concept that diversity of the hairy root tip—cell division, elongation, and maturation regions—is necessary for optimal growth rate (15). The best growth of root tips is consistent with the formation of new branches in maturation zones and enhancement of apical dominance (14). 

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