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. 2016 Mar 8;110(5):1139–1149. doi: 10.1016/j.bpj.2016.01.010

Figure 2.

Figure 2

Single-particle tracking of individual lipid dye molecules and diffusion analysis. (A) Time-lapse images of a DiI-C12 molecule tracked in the cytoplasmic membrane of a live E. coli cell (horizontal scale bar, 1 μm). Indicated are frame numbers; time interval between two consecutive frames = 12 ms. (B) Illustration of a simulated 3D diffusion trajectory in the curved membrane of an E. coli cell. (C) Simulated MSD (left) and CPD (right) curves in 3D (blue) and projected in 2D (gray). As illustrated, 2D projection yields a 30% reduced diffusion coefficient using MSD analysis and distorts the monoexponentially decaying CPD of 3D displacements. (D) Schematic of IPODD: 2D displacement distribution (gray) can be processed via IPODD to find the most likely 3D displacement distribution (blue). Fits to Rayleigh distributions (red) indicate that the distortion introduced by 2D projection is restored in the resulting 3D displacement distribution (42).