Fig. 5. Loss of east leads to abnormal movements of chromosomes during prometaphase. Time-lapse recordings of cell divisions in mitotic domains of live embryos expressing histone—GFP reveal irregular patterns of congression to the metaphase plate (see Movies 2 and 3, http://jcs.biologists.org/supplemental). The beginning of prometaphase is chosen as timepoint zero. (A) In control embryos, on nuclear envelope breakdown, condensed chromosomes remain clustered in the center of the cell and rapidly orient themselves perpendicular to the future axis of division (+02:00). (B) In east(mat)^hop-1, chromosomes were seen to break up into distinct clumps of DNA or (C) to stray to the periphery of the cell. Compare A and C at timepoint +02:00 minutes: chromosomes in the wt cell are aligned centrally perpendicular to the future axis of division, whereas the chromosomes in east mutant cell are positioned near the cell cortex parallel to the future axis of division. Compare the three live recordings at timepoint +04:30 minutes: while chromosomes in the control cell are undergoing anaphase (A), chromosomes in the east cells are still split up into distinct groups (B) or located near the cortex in an abnormal orientation (C). However, with a time delay, chromosomes in mutant cells eventually manage to arrive in the center and complete mitosis. Stippled lines outline the boundaries of the cells.