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Movies 1A-G.
These movies correspond to the nuclei in Fig. 1, except that there is no corresponding movie for Fig. 1H. Movies are labeled with the same letter as in Fig. 1. These movies illustrate chromatin rearrangement and bouquet formation in meiotic prophase of maize. Images of each nucleus were acquired using a DeltaVision Microscopy system (Applied Precision) followed by computational deconvolution (see Golubovskaya et al., 2002). This results in a 3D data stack. Shown here are 3D rotations of whole nuclei. There is always some distortion in the Z dimension (going towards and away from the objective), which often results in the apparent elongation of structures when the nuclei are viewed on their sides (halfway through each movie). Chromatin (stained with DAPI) is shown in red, telomeres (FITC) are shown in green, centromeres (Cy3 or Cy5) are shown in blue in A, B, G, and the single 5SrRNA (Cy3 or Cy5) locus is shown in blue in C, D, F, H. In movie 1E, chromatin is shown in blue, 5SrRNA in red, and telomeres in green to enhance visualization of the pairing 5SrRNA foci.
Files in this Data Supplement:
Movie 1A. Leptotene. Telomeres and centromeres are distributed throughout the nuclear volume. Chromosomes can be seen as thin threads almost like beads on a string, and heterochromatin knobs appear spherical.
Movie 1B. Late Leptotene. Telomeres are attached to the inner surface of the nuclear envelope (NE). Centromeres are distributed throughout the nuclear volume. Chromosomes are still completely unsynapsed but appears more condensed.
Movie 1C. Early Zygotene. Telomeres are gathered in a narrow patch on the NE, but are not yet completely clustered. Chromatin is more condensed, and some regions are beginning to synapse. This can be seen more easily in the supplemental material as thicker and apparently paired regions of the chromosomes. Some knobs are round, and some are elongated. The two 5SrRNA foci, seen here as blue dots, one on each homolog, are obviously not paired.
Movies 1D and 1E. Classic Zygotene. Telomeres are clustered in the bouquet. These cells are very typical of the maize bouquet. Chromatin structure has not changed from earlier zygotene, except that more chromosome regions are paired. This is readily apparent in the supplemental material. The 5SrRNA foci are still not paired, but we imagine that they are in the process of pairing in E (compare distances between 2 foci in C, D and E).
Movie 1F. Pachytene. All chromosomes are completely paired and synapsed. This can be seen as a doubled chromatin width (compare E and F), and there is only one 5SrRNA focus. All telomeres are still on the NE, but they are beginning to disperse from the bouquet.
Movie 1G. Late Pachytene. All chromosomes are still completely paired and synapsed, but telomeres are being released from the NE. Centromeres (G) are dispersed throughout the nucleus. The chromatin appears thinner in G due to a different fixation.
Movies 2A and 2B. These movies show the polarization of centromere and telomeres at the leptotene-zygotene transition. This stage is very transient and rarely seen. Notice that almost all of the telomeres are in one hemisphere while almost all centromeres are in the opposite hemisphere.
Movie 3. This movie shows an S. pombe nucleus in the horsetail stage (bouquet stage). The centromeres and telomeres are labeled with swi6-GFP, which is a component of heterochromatin. There is a green background in the entire nucleus. The bright green dot at the leading edge is the telomere cluster. The fainter dots inside the nucleus are the centromeres. This movie was acquired by Carrie Cowan while at UC Berkeley using a DeltaVision Microscopy system (Applied Precision).
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