Fig. 1
From: N-Cadherin based adhesion and Rac1 activity regulate tension polarization in the actin cortex
Micropipette aspiration for cortical tension quantification. (a) A schematic of the aspiration process for a single suspended cell. An aspiration pressure, \(\triangle P\), in the range of 40-250 Pa is applied to deform the F-actin cortex. The Young-Laplace equation is used to extract cortical tension. \(R_{\textrm{p}}\) is the micropipette radius, \(R_{\textrm{c}}\) is the cell radius, \(L_{\textrm{p}}\) is the length of cell aspirated into the micropipette, and \(\gamma _{0}\) is the cortical tension for single suspended cells. \(\Delta P_{cr}\) is the pressure when \(L_{p}=R_{p}\) is reached. (b) A single engineered L929 cell expressing a relatively high level of N-cadherin receptors (LAN-High) and undergoing aspiration was observed in bright-field, RFP, and GFP channels. Arrowheads indicate the aspirated region. Scale bar is 10 µm. (c) An example of the applied aspiration pressure profile with 30-sec hold time (left axis) and the corresponding evolution of the normalized protrusion length, \(L_{p}/R_{p}\) (right axis); \(n=5\). (d) Dependence of cortical tension measurement on the hold time. \(n=16\) for 10, 20, and 30 s; \(n=9\) for 60 s.
