PMC

Forest plot of the included studies comparing (A) UC overall rate of extension. Extension over the time: (B) UC overall rate of extension at 5 years and (C) UC overall rate of extension at 10 years

Inhibition of integrin-laminin interactions with a β1 integrin function-blocking antibody (AB) decreases axon extension rate and attachment. (A) On laminin coated substrata, 11 μg/mL of the β1 integrin antibody inhibited axon extension rate by 57%, while 2.2 μg/mL of the antibody did not affect axon extension rate. As a control, treatment with 22 μg/mL of an anti-tubulin antibody (DM1A) did not affect extension rate. Treatment of axons growing on polylysine with 11 μg/mL of the anti-β1 integrin antibody did not affect extension rate. Data collected from pre and post antibody treatment experiments. Paired t-test used for comparisons. n = axons. (B) Effects of the β1 integrin antibody on neuronal cell attachment to laminin or polylysine coated substrata. The concentration of β1 integrin antibody that decreased axon extension rate by 57% (11 μg/mL) inhibited cell attachment on laminin by 47%. Treatment with 11 μg/mL of the control anti-tubulin antibody did not affect attachment on laminin. Treatment with 11 μg/mL of the β1 integrin antibody did not affect attachment on polylysine. Welch t-test used for comparisons. n = 16 cultures per group.

Characteristics of TobLTP2-Mediated Cell Wall Loosening.
(A) Extension rate of cucumber hypocotyl cell walls upon incubation with 5 μg/mL LTP inactivated by benzene (plus sign) or β-sitosterol (closed circle) and applied at the time indicated by the symbols. After 20 to 25 min of incubation, the LTP inhibited by benzene or β-sitosterol was removed by washing the hypocotyls. Fresh LTP (5 μg/mL) was then applied (arrowheads) to confirm that the hypocotyl cell wall was still responsive to LTP activity. All extension rate graphs show representative results from five independent measurements. The average relative increases in extension rate were 0.9 ± 0.2 (LTP preincubated with β-sitosterol), 3.8 ± 1.0 (fresh LTP, β-sitosterol), 0.9 ± 0.2 (LTP preincubated with benzene), and 3.9 ± 0.8 (fresh LTP, benzene).
(B) Cell wall–loosening activity of LTP at different pH values. The relative increase in extension rate was calculated by dividing the maximum extension rate by the rate just before LTP addition.

Visual representation of phytomer extension. The phytomer is shown at nine stages: (1) and (2) the leaf extension zone consists only of blade tissue; (3) tip emerges and sheath is initiated; (4) blade starts the linear phase as ; (5) sheath is still in exponential mode and occupies a growing fraction of the leaf extension zone, so the length of the blade extension zone decreases (blade still extends rapidly, but at a decreasing rate); (6) sheath starts linear extension as collar of the previous phytomer emerges; (7) blade extension stops as sheath occupies the whole leaf growing zone; (8) sheath extension has stopped due to its emergence out of the tube; internode has either stopped (short internode) or started linear extension (long internode); (9) internode has completed its linear extension. The key events involved in the coordination rules are shown as vertical arrows. The phases of extension are shown below. Note that, in order to position all important events, this scheme does not take into account the change of rules for sheath dynamics at tassel initiation: the rules for sheath are shown for the period before tassel initiation, while the internodes have a period of linear extension only after tassel initiation.