Imaging chromatin in embryonic stem cells∗

Chromatin recently emerged as one of the governing factors for self-renewal and pluripotency of embryonic stem (ES) cells. Stem cell chromatin is distinct from that of somatic or differentiated cells in several different structural and functional aspects including chromatin modifications, global chromatin arrangement and condensation and compaction of chromosome territories. Live imaging methods further demonstrate that chromatin-binding proteins are more dynamic is ES cells. Here I review recent advances in imaging methods that allow investigations of chromatin and chromatin proteins, mostly in embryonic stem cells, and suggest that the nucleus itself in undifferentiated ES cells is less constrained, giving rise to a ‘breathing’ chromatin conformation in ES cells.