[Changes in the structure of the chromosomal nucleohistone fibrils on removal of divalent cations and histone H1].

A technique of freeze--drying was applied in studies on submicroscopic organization of metaphase chromosomes from Chinese hamster. In the buffer without bivalent cations the chromosomes increased in size; the removal of bivalent cations with EDTA resulted in a large swelling of chromosomes. Regularly organized nucleosomal filaments of a "beads-on-a-string" type appeared on the periphery of chromosomes. The regular organization of the fibers is damaged as soon as histone H1 is removed. An increase in the ionic strength of solution in the absence of bivalent cations results in chromosome compactization, although the regular fibrillar structure being not restored.