Figure 3.

The chromosomal context of human NORs located on acrocentric short arms. (A) Schematic human acrocentric chromosome short arm showing the NOR (rDNA array), expanded below into rDNA repeats, and the PJ (orange) and DJ (green) regions. The DJ region is further expanded to show the location of inverted repeats (light green arrows), DJ promoters and transcripts, Acro138 repeat blocks (red), and CER satellite (blue). (B) Cartoon showing the transition from normal nucleolar organization to segregated nucleolar organization in response to AMD treatment or the introduction of rDNA double-strand breaks (DSBs). rDNA (red) retreats from the nucleolar interior (black) to the nucleolar periphery, forming caps adjacent to DJ sequences (green) that are embedded in PNH (dark blue) (Floutsakou et al. 2013; van Sluis and McStay 2015).