DEV00603 Movies

Files in this Data Supplement:

• Movie1 - Mitoses at the neural plate stage are parallel to the neuroepithelium (refer to Fig. 2). Neural plate of a zebrafish embryo during convergence to form the neural keel. The embryo received an injection of mRNA encoding tau:GFP at the two-cell stage; the right half of the neural plate is labelled more strongly than the left half. Notice the planar orientation of the mitotic spindle and the ensuing mitoses throughout the neural plate. The overwhelming majority of cells in the neural plate divide apically. Prior to division, many cells form processes, which are polarised towards the midline. One of those cells, which can be observed through most of the movie, is indicated with an arrow. This cell undergoes convergence approximately above the cells, which were its neighbours prior to leaving the epithelium in order to divide. One of those neighbouring epithelial cells is indicated with an asterisk. Notice that the more lateral of the daughter cells reintegrates into the epithelium.
• Movie 2 - Mitoses at the neural plate stage are parallel to the neuroepithelium (refer to Fig. 4). A fragment of the neural plate (surrounded by the large nuclei of the enveloping layer) of a Tg(H2AF/Z)^kca37 ; Tg(H2AF/Z)^kca66embryo has been photographed from above at 1 minute intervals. Anterior is towards the left. Cell nuclei can be seen to converge towards the midline (in the middle) and to sink-in during the process of neural plate in-folding to form the neural keel (out of the plane of focus). As convergence proceeds, the width of the neural plate shrinks. Notice that all mitoses are planar, i.e. parallel to the neuroepithelium. Anterior is towards the left.
• Movie 3 - Mitoses at the neural keel/rod stage are perpendicular to the neuroepithelium (refer to Fig. 5). The neural rod at the level of the transition between hindbrain and spinal cord (in the middle surrounded by the somites) of a Tg(H2AF/Z)^kca37 ; Tg(H2AF/Z)^kca66embryo has been photographed from above at 1 minute intervals. Mitotic divisions occur at the region of apposition of the walls of the neural rod, i.e. the apical poles of the neuroepithelial cells (in the middle of the neural rod). One of the many mitoses visible in this time lapse is labelled with arrows. Notice that the two daughter cells integrate on opposite sides. The same applies to all the other mitoses visible in this movie. Anterior is towards the top.
• Movie 4 - Mitotic spindle forms parallel to the neuroepithelium and rotates by 90° (refer to Fig. 5). Mitosis at the neural rod stage of an embryo that expresses tau:GFP. Notice that the centrosome divides, both centrosomes migrate to opposite poles, and the spindle forms prior to rotation. After division, daughter cells are incorporated on opposite sides. Anterior is towards the top.
• Movie 5 - Mitoses at the neural tube stage are parallel to the neuroepithelium (refer to Fig. 4). Mitoses at the neural tube stage of a Tg(H2AF/Z)^kca37 ; Tg(H2AF/Z)^kca66embryo. The neural tube is visible in the middle surrounded somites on both sides. One nucleus has been highlighted with an arrow at 19 minutes. This cell will divide later (arrow at 43-63 minutes). Notice that the plane of cleavage in all mitoses is perpendicular to the neurocoele.
• Movie 6 - Stereotypic orientation of the mitotic spindle changes from neural rod to neural tube. Time-lapse movie (1.5 minute intervals) to show the progressive change of mitotic spindle orientation during the transition from neural rod to neural tube. Arrows indicate divisions in different orientations. The arrows between 4.5 and 27 minutes point to a mitosis whose products integrate in different sites, corresponding to the pattern at the neural keel/rod stage. A mitosis is shown between 28.5 and 57 minutes with an oblique orientation of the spindle. However, both daughter cells integrate on the same side of the neural rod. Finally, the arrows from 82 minutes to 111 minutes point to a division with a parallel orientation of the mitotic spindle, corresponding to the pattern characteristic of the neural tube stage. Several examples of all three types can be seen.
• Movie 7 - Post-mitotic cells migrate into subventricular regions (refer to Fig. 6). Time-lapse movie (1.5 minute intervals) of a Tg(H2AF/Z)^kca37 ; Tg(H2AF/Z)^kca66 embryo to illustrate the migration of post-mitotic cells to the subventricular region of the neural tube. The embryo is oriented slightly obliquely, such that both halves are not in register. One cell in metaphase has been marked with an arrow in 16.9. Orientation of the metaphase plate is dorsoventral. After division in 31.2 (arrows indicate both daughter nuclei), one of the nuclei (left arrow) moves towards the subventricular region to join differentiating cells in the external region of the spinal cord. Notice the migrating cells of the primordium of the lateral line organs at the top of the photographs. Anterior is towards the left.