Figure 1. Somatic H1 Cannot Substitute for H1M at Endogenous Concentrations.
(A) Individual chromosomes assembled in mock-depleted (ΔMOCK) or H1M-depleted (ΔH1M) extracts, or H1M-depleted extracts supplemented with 0.4 μM or 1.5 μM H1M or H1A. H1M consistently rescued more efficiently than H1A, even at lower concentrations.
(B) Quantification of chromosome morphology from the experiment described in (A). Images of individual chromosomes (n > 30) were thresholded and their average fiber lengths and breadths calculated and plotted.
(C) 3.5 μM somatic H1 rescues H1M-depleted chromosome morphology similar to a lower concentration of H1M. Average lengths and breadths of individual chromosomes (n > 40) and representative chromosomes are shown. Since somatic H1 causes interphase compaction at this concentration, H1 proteins were added only at the onset of mitosis. Scale bars, 10 μm; error bars, standard error. See also Figure S1.