Abstract.
When DNA topoisomerase II (topo II) activity is inhibited with a non-DNA-damaging topo II inhibitor (ICRF-193), mammalian cells become checkpoint arrested in G2-phase. In this study, we analyzed chromosome structure in cells that bypassed this checkpoint. We observed a novel type of chromosome aberration, which we call Ω-figures. These are entangled chromosome regions that indicate the persistence of catenations between nonhomologous sequences. The number of Ω- figures per cell increased sharply as cells evaded the transient block imposed by the topo II-dependent checkpoint, and the presence of caffeine (a checkpoint-evading agent) potentiated this increase. Thus, the removal of nonreplicative catenations, a process that promotes chromosome individualization in G2, may be monitored by the topo II-dependent checkpoint in mammals.
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Received: 19 July 1999; in revised form: 20 October 1999 / Accepted: 7 January 2000
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Giménez-Abián, J., Clarke, D., Devlin, J. et al. Premitotic chromosome individualization in mammalian cells depends on topoisomerase II activity. Chromosoma 109, 235–244 (2000). https://doi.org/10.1007/s004120000065
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DOI: https://doi.org/10.1007/s004120000065