Figure 3.

Single-molecule detection and tracking. (a) Illustration of the excitation path and cross section of the embryo at the region of interest. Imaging at the lower left quadrant of the embryo reduced optical aberrations. (b) Single raw image of 10 kDa Dextran-Alexa647 and the temporal average of NrgGFP with superimposed trajectories. Scale bar, 10 μm. Subregion and tracks show examples for fast (left), medium (center), and slow (right) particles. Scale bar, 5 μm. (c) Cumulative distribution function (CDF) of jump distances pooled from three different embryos and a three-component fitted model. Additionally, the CDF and a fitted curve (two-component model) are shown for Rab5-GFP particles found in the Drosophila embryo. (d) Example of Alexa647 bleaching steps found during the first seconds of imaging with the 642 nm laser line.