Chromosome condensation in Xenopus mitotic extracts without histone H1.

The contribution of histone H1 to mitotic chromosome condensation was examined with the use of a cell-free extract from Xenopus eggs, which transforms condensed sperm nuclei into metaphase chromosomes. When H1 was removed from the extract, the resultant metaphase chromosomes were indistinguishable from those formed in complete extract. Nucleosomal spacing was the same for both. Thus, H1 is not required for the structural reorganization that leads to condensed metaphase chromosomes in this egg extract.