A 7 nt insert between positions 187 195, apparently interacts with a 7 nt tract between positions 305 311 (see Figure 4) and is predicted to result in a slight alteration of the secondary structure between conserved elements 20 and 25 [ 40], resulting in an extension of the stem between elements 20 and 22 and the formation of a 4 bp and a 7 bp stem loop between elements 23 and 25 (see Figure 4).
In line with these considerations, AR PC axons in vitro undergo simultaneous extension of both stem axon and terminal tree.
Regardless of their age, cultured PCs appear to recapitulate an intrinsically coded program, involving initial navigation of the main neurite towards the target field and subsequent expansion of the terminal trees, accompanied by interstitial extension of the stem axon.
Several studies have shown that the Wnt7A/FZD7 pathway establishes front-rear cell polarity and directional migration of human myogenic progenitors and facilitate the extension of satellite stem cells, all by activating PI3K/Akt pathway and Rac1 (Bentzinger et al., 2014, 2013).
Another type of meristem of limited life is called intercalary; it is responsible for the extension of some stems (as in the grasses) by the addition of new tissues remote from the growing points.
Rosenblatt, a well-known PBS commentator and the author of eight previous books, promises in his preface that his book, written in "an extension of feeling stemming from Sept. 11," is the "larger story" about America that for many years "was writing itself in my mind".
The work utilizes elegant mouse modeling to demonstrate a previously unrecognized mechanism of Hh ligand delivery to the hippocampal stem cell population and elucidates a fascinating extension of the hippocampal "stem cell niche" outside of the brain.
Think of these lobes like "leaf fingers", or extensions of the stem.
Development on the main stem proceeds by the accumulation of primordia on the apical meristem, their development into physical structures, the extension of the true stem up through the enveloping leaf sheaths, the emergence of the ear, anthesis (through grain filling) and physiological maturity (Kirby, 1990 , 1993 Kirby et al., 1999).
Further extension of the hairpin stem results in a loss of RNAi activity.
The total axon length, calculated by adding up the extension of the main stem and terminal branches (Figure 1C), was significantly higher in postnatal than in embryonic PCs (Figure 1D; E17, 281.40±18.40 µm; P0, 502.57±27.85 µm; Mann-Whitney Rank Sum Test, P<0.001).
