Fig. 4

Two-color mixing assay for determination of the material state of chromatin condensates. 12-mer nucleosomal arrays (60 bp linkers) were reconstituted with recombinant Xenopus histone octamers in which histone H4 was labeled with Alexa 488 or Alexa 649. Labeled arrays were incubated in either 4 mM MgCl₂ (A) or 150 mM K Acetate/1 mM Mg Acetate plus 0.1 mg/ml BSA, 5 mM DTT, and 5% glycerol (B) to form condensates. The green and red labeled condensates were then mixed for 20 min, followed by fluorescence microscopy. Shown are the images obtained in the green channel (left), red channel (center), and overlay (right) after the 20 min incubation. Data courtesy of Dr. Thomas Tolsma