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. 2021 Jan 16;120(4):607–617. doi: 10.1016/j.bpj.2021.01.009

Figure 2.

Figure 2

Stretching increases the oil concentration in the bilayer depending on the phospholipid composition. (A) Schematic representation of the triolein DEV formation protocol. To report triolein distribution, triolein was supplemented with 0.05% (w/w) triolein-NBD. (B) Left shows confocal images of PC triolein DEVs under hypotonic shock with triolein tagged by triolein-NBD. Line scans show a triolein-NBD signal colocalizing with the bilayer. Scale bars, 5 μm. Right shows corresponding quantification of triolein-NBD signal and bilayer area variation. During bilayer stretching, triolein-NBD signal increased and quickly dropped after deflation. (C) Representative confocal fluorescence images of a PC triolein DEV at the maximal bilayer expansion state (high tension) and at the “unstretched” state (low tension). Line scans allow for quantification of triolein-NBD fluorescence intensity in the bilayer in each state. “Triolein enrichment” was computed by taking the fluorescence ratio between stretched state/unstretched state. Scale bars, 5 μm. (D) Triolein enrichment measured for PC (n = 8), PA-PC (n = 5), PE-PC (n = 4), DPPC-PC (n = 3), and PufaPC-PC (n = 8) triolein DEVs. Mean ± SD. (E) Plot of the critical bilayer strain ratio between DEVs/GUVs against the triolein enrichment for previous phospholipid compositions. Statistical analysis revealed a significant slope different from zero for a linear fit (dotted lines). Mean ± SD. ***p < 0.001; **p < 0.01; *p < 0.05. To see this figure in color, go online.