... stretching was performed in 100 mm NaCl,1.5 mm MgCl2. The stretching profiles were recordedwith either constant stretching speeds or at constantforce. The force–extension curves showed characteristicsawtooth ... thechromatin fiber [9–11] as well as for the maintenanceKeywordschromatin, micro-manipulation, nucleosome,optical tweezersCorrespondenceJ. Bednar, CNRS, Laboratoire deSpectrometrie Physique, ... ofhistone H3 or its phosphorylation, is essential forchromosome condensation. EMBO J 20, 6383–6393.13 Scrittori L, Hans F, Angelov D, Charra M, Prigent C& Dimitrov S (2001) pEg2 aurora-A kinase,...