Nuclear labeling and DNA content tracking with Histone-2B fluorescent fusion protein.

(A) Fluorescence and brightfield micrographs showing uniform PGK-H2BeGFP fluorescence in nuclei of cardiomyocytes derived from a FACS-enriched stable line. Spontaneous contractile activity is apparent in Supplemental Movie S1. H2B eGFP expression correlated with DAPI by flow cytometry (R2 = 0.733, see text). (B) Examples of tracking of PGK-H2BmCherry hESCs cells, also from a FACS-enriched stable line, undergoing cytokinesis at the border of an undifferentiated colony. Lower left inset shows fluorescence intensity of 10 images before and 10 images after cell division of the individual cells in the larger figure (n = 5). Upper right inset shows heatmap representation of H2BmCherry fluorescence intensity of a single dividing cell. (C) Tracks calculated automatically using ImageJ Plugin [17] from time-lapse images of H2BmCherry fluorescence at the border of undifferentiated ESC colony over a 2 day period (Methods). Yellow boxes indicate frames of movie clips in Supplemental Movie S2. (D) Time frames showing a single track of the H2Bmcherry centroid (blue).