Fig. 1.

ES cells present an atypical organization of microtubules in interphase with nucleation centers. 3D confocal images of ES cells co-transfected with H2B-mCherry (red) and EMTB-3xGFP (green) (A, B) or EB3-GFP (C, D). A 3D reconstruction of representative cells showing the organization of the microtubule network (Additional file 1: Supplementary Video S1 and Additional file 2: Supplementary Video S2). Other examples of 3D reconstructions can be found in Additional file 14: Supplementary Fig. S6. B Maximum intensity projection image merged with the transmission image collected at a single plane of the z-stack; the arrow points to a microtubule-enriched cellular protrusion extending to another cell. The top image was digitally saturated to facilitate the observation of the protrusion. C Representative, single-plane image of a cell expressing EB3-GFP (top); zoom-in images of the cell region delimited by the dashed square at four different frames of the time-lapse movie showing an EB3 comet in close contact to the nucleus (bottom). D Maximum intensity projection images obtained from a 100-image stack obtained during a time-lapse experiment lasting 166.6 s (left); flow maps of the EB3-GFP comets (right). The pink asterisk shows a microtubule nucleation center from which EB3 comets emanate. Scale bars: 10 μm. Other examples of the analysis of EB3 comets can be found in Additional file 15: Supplementary Video S8