Extended Data Fig. 3: Characterization of histone-depletion.

(A) Bright field images of a chromosome before and after histone depletion by treatment with 1 M mono valent salt for 15 min. (B) Fluorescence images before and after histone depletion of a chromosome stained with the intercalator SYBR Gold. Scale bar equals 2 μm. (C) Box plot of the Chromosome length at 50 pN before, during and after histone depletion by treatment with 1 M monovalent salt for 10 min (in the presence of polyamines), N = 10 chromosomes. The box plot marks the quartiles of the distribution, the whiskers show the whole distribution, and the center line marks the median. (D) Following the depletion of histones by monitoring the fluorescence intensity of EGFP-labelled H2B (N = 4 chromosomes). Here, control refers to imaging of the chromosome while in regular buffer to account for bleaching (N = 2 chromosomes). (E) Monitoring the stability of histones under force by measuring the fluorescence intensity of EGFP-labelled H2B (N = 4 chromosomes). The chromosome was kept for 5 minutes at the respective force and the EGFP intensity was measured before and after that force clamp. While there is some bleaching due to multi-photon absorption of the trapping laser, there is no impact of the force. Error bars show the standard error of the mean.