1. Elastic Properties of Pore-Spanning Apical Cell Membranes Derived from MDCK II Cells 
Stefan Nehls, Andreas Janshoff 
Biophysical Journal 
Volume 113, Issue 8, Pages (October 2017)
DOI: /j.bpj
Copyright © 2017 Biophysical Society Terms and Conditions

2. Figure 1
Schematic representation of membrane patches yielded by sandwich cleavage. The membrane (red) on a porous mesh (gray) is still containing actin (green) and linker proteins (blue). To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2017 Biophysical Society Terms and Conditions

3. Figure 2
Parameterization of a conical indenter (empty triangle) with half-opening angle 90°−θ poking into a flat circular membrane. Without indentation, the membrane will be at the same height as the rim (black boxes left and right), giving u(r) = 0. During indentation to a total indentation depth of utot, the membrane (red line) will be deformed into the pore. Two parts of the membrane will be treated separately; the inner part will stick on the conus’ surface, whereas at the certain movable contact point (r = a, u = ua) the membrane will free itself from the conus. To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2017 Biophysical Society Terms and Conditions

4. Figure 3
Fluorescence images of membrane patches deposited on porous substrates. Staining of apical membrane in red with CellMask Orange (a) and F-actin in green using phalloidin (b) shows an inhomogeneous distribution of actin on top of the patches. The patch on the top right (arrow) generates almost no intensity from attached actin, whereas the other patches show remnants of the cortex especially associated with microvilli. Staining of F-actin (red, c) and ezrin (green, d) shows colocalization in pointlike structures identified as microvilli. Similar patterns are found in cultured MDCK II cells stained for F-actin (red, e) and ezrin (green, f). Scale bars, 20 μm. To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2017 Biophysical Society Terms and Conditions

5. Figure 4
Scanning ion conductance microscopy image of the surface of MDCK II cells after fixation with paraformaldehyde. Protrusions from the cell surface, i.e., microvilli, are visible as small bright features. Scale bar, 5 μm.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2017 Biophysical Society Terms and Conditions

6. Figure 5
FRAP of apical membrane patches. Shown are the fluorescence micrographs of membrane-labeled patches before (a) and immediately after bleaching (b). The fluorophores were bleached in four spots on four different patches. After 2 min, the homogenous distribution of fluorophores was restored (c). Bottom-right panel shows the average recovery of fluorescence intensity. Scale bars, 20 μm. To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2017 Biophysical Society Terms and Conditions

7. Figure 6
Force-distance curves (a) obtained from different locations on substrate-supported apical membrane patches. Indentations performed on the rim (black, left pictogram) as well as on empty pores (blue, right pictogram) show a very steep increase of force due to hard-wall repulsion. Indentations in the center of membrane-covered pores show a complex nonlinear force response (red, green, mid pictogram). Membrane rupture is indicated as a sudden decrease of force (red). The fit (b, line) according to Eq. 12 nicely represents the experimental data (crosses). The results of the computation of membrane shape (small pictograms, jet colormap) during deformation by a cantilever (gray colormap) are shown for indentation depths of 100 nm (left) and 300 nm (right). To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2017 Biophysical Society Terms and Conditions

8. Figure 7
Logarithmically scaled histogram of compressibility moduli KA (a) and linear histogram of prestress T0 (b) values obtained from isolated apical membrane sheets deposited on porous materials and subjected to central indentation. Distributions are shown as histograms (bars) with kernel density estimation (dark line). Total number of values is n = 350 with the highest probability at KA = 27 mN m−1 and T0 = 0.36 mN m−1. To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2017 Biophysical Society Terms and Conditions

9. Figure 8
Kernel density estimates of KA (a) and T0 (b) for the different treatments of apical membrane sheets. The apparent area compressibility modulus KA is highest after treatment with GDA (blue) and lowest after treatment with Pronase E (red), whereas untreated cells (green) show values in between. Prestress values T0 are very similar regardless of the treatment. To see this figure in color, go online.
Biophysical Journal  , DOI: ( /j.bpj )
Copyright © 2017 Biophysical Society Terms and Conditions