PhD defence M.E. (Maria) Oomen

Chromosomes are the structural units that contain the information of our genome. Therefore, chromosome folding is tightly modulated in order to enable transcriptional regulation, protection from DNA damage and maintenance of epigenetic characteristics. Seemingly counterintuitive, chromosomes undergo dramatic conformational changes as cells progress through the cell cycle. After DNA replication, sister chromatids need to detangle and ultimately condense in order to enable proper separation into the two new daughter cells in mitosis. Even more striking, iconic interphase structures such as TADs and compartments are dissolved in mitosis and mitotic chromosomes are organized in a helical loop array mediated by loop extruding machineries. However, mitotic bookmarks such as histone modifications, histone variants and even certain chromatin binding factors are maintained, which
could enable the fast reestablishment of the interphase chromosome organization upon mitotic exit. The scope of this thesis has been to explore the characteristics of mitotic
chromosomes. On a small scale, we have studied the binding dynamics of CTCF, a key architectural protein in interphase chromosomes, and the mitotic bookmarks around CTCF binding sites in differentiated cells and stem cells. On a larger genomic scale, we observed interactions between and along sister chromatids in budding yeast, for which we developed a novel Hi-C technique, SisterC.

Due to corona, the PhD defences do not take place publicly in the usual way in the Senate Hall or in the Professor Andries Querido Room. The candidates will defend their dissertation either in a small group or online.