(Color online) Dependence of the apparent length of the labeled segment on its real length as given by Eq. (16) for (close to the aspect ratio of the sampling volume in our setup). The lengths are given in the units of confocal volume radius , . The apparent length of very long segments approaches . Inset: Ratio of the apparent length to the real length of the labeled segment. Labeled segment lengths of result in .
(Color online) Calculated dependencies of FCS correlation function on the transverse mean-square displacement of semiflexible polymer segment. FCS correlation functions are normalized by their zero-time values (to have unit amplitude) and transverse MSD is given in the units of confocal volume radius . The dashed curve is given by standard FCS expression Eq. (14) for isotropic motion. The other curves are calculated from Eq. (12) and its limiting cases, Eqs. (13) and (15), for different values of , left to right: 0, 1, 2, 5, 15, . Inset: Same curves in semilog scale allowing to assess wider range of .
(Color online) Photon count trace of partially labeled actin filaments (sample 1). The photon trace is collected with resolution and split into bins. The data points represent photon counts per bin. (a) Full trace over the duration of one measurement, (b) zoom into first of measurement. Bursts (dotted line) due to the passage of labeled parts are separated by the intervals of background noise (solid line).
(Color online) Total (dotted line), background (thin solid line), and signal (thick solid line) correlation functions of partially labeled filaments (sample 1). is obtained by analyzing the complete photon trace, is caused by the diffusion of free fluorophore and is calculated from the photon trace in between the bursts in Fig. 3. is the correlation function resulting from the motion of F-actin labeled segments after background subtraction. The dashed line is the correlation function of homogeneously labeled actin (sample 2) after subtraction of background noise. The correlation function of sample 2 was normalized to have the same amplitude as that of sample 1 in order to facilitate the comparison of temporal behavior.
(Color online) The kinetics of random motion of actin filaments’ segments. Experimental measurements on locally labeled (full circles) and on homogeneously labeled (open circles) are compared to the theoretical predictions. Solid line: hydrodynamic theory of Kroy and Frey (Ref. 15). Dashed lines (top to bottom): hydrodynamic theories of Harnau et al. (Ref. 12), of Granek (Ref. 14) and nonhydrodynamic theory. The parameters used for the calculation are , filament diameter of , solvent viscosity , and filament length of .
(Color online) Theoretical fits to the experimental measurements of monomers’ MSD Circles: data on homogeneously labeled actin filaments. Solid line: fit with Granek theory (Ref. 14). Fit line with the theory of Harnau et al. (Ref. 12) is almost indistinguishable from the solid line and is not drawn. Dashed line: fit with the theory of Kroy and Frey (Ref. 15). See text for the fitting parameters and discussion.
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