(A) Immunofluorescence of 3xFLAG-tagged DPY-21 confirmed the cell-cycle dependent recruitment of DPY-21 to X chromosomes. Enlargements of individual nuclei at different stages of the cell cycle from a confocal image of a
dpy-21(5'-FLAG) XX embryo at 277-cell stage stained with DAPI and antibodies against SDC-3, DPY-27 and FLAG. 3xFLAG-tagged DPY-21 colocalizes with SDC-3 and DPY-27 on X during interphase but dissociates from X during mitosis, while SDC-3 and DPY-27 remain on X throughout the cell cycle. Scale bar, 1 um.