Multiple chromosomal populations of topoisomerase II detected in vivo by time-lapse, three-dimensional wide-field microscopy

A study analyzes the in vivo distribution of DNA topoisomerase II (topo II) during the cell cycle of living Drosophila melanogaster embryos through time-lapse, three-dimensional, wide-field sequences. The nucleus is revealed to have three separate topo II populations of a spatially and temporally regulated localization. Topo II's exodus from the nucleus during mitosis and its ability to localize on sites which are precisely needed by the chromosome indicate the impact of separate pools on chromosome condensation and topo II's use in forecasting structural dynamics in chromosomes.