Fig. 5: In-vivo single-particle tracking and microrheology with EB-NS.

a Experimental scheme for microinjection of EB-NS into syncytial Drosophila embryos. During the syncytial blastoderm stage, the peripheral nuclei are linked to the actin cortex of the plasma membrane (red). b EB-NS (red) inside a Drosophila embryo during gastrulation stage (stage 6) expressing Histone2Av-GFP (green) that labels the nuclei. Overview and magnified region (orange rectangle) with GFP (green), NIR EB-NS (red), and overlay channels are shown. Arrows pinpoint to the two EB-NS in this field of view. Scale bar = 10 µm (overview) and 5 µm (other channels). c Color-coded trajectories representing the instantaneous velocity of three tracked nanosheets moving in the space between the nuclei (lag time = 0.1 s). Particles #1, #2, and #3 have diameters (measured in the image) of 0.64 µm, 0.68 µm, and 0.52 µm, and are most likely resolution-limited. Scale bar = 5 µm. d Van Hove histogram of displacements of two subpopulations of injected EB-NS: close to nuclei vs. distant from nuclei. The distance (Δr) was computed for all points of all trajectories as the minimum distance to the border of any nucleus. e Van Hove plot of all tracked EB-NS and Gaussian fit for small displacements (range [−0.03 μm, +0.03 μm]). The tails (see arrows) of the distribution exceed the Gaussian curve, which indicates the presence of active processes in Drosophila that lead to larger displacements than expected from thermal motion. n = 38 tracked EB-NS (21 embryos).