Self-organization of histone-jointed three-dimensional DNA network

A three-dimensional deoxyribonucleic acid (DNA) network was self-organized in a space between two cover slips, which was filled with an aqueous solution of lambda DNA mixed with multivalent cations such as Ca2+ and histone; the former behaves as a DNA fixation factor on the cover-slip surface and the latter as a junction and pillar construction factor for the network. The geometry and the components of the three-dimensional DNA network thus formed were observed by fluorescence microscopy. It is revealed that (1) the three-dimensional network is based on two-dimensional networks formed on the inner surfaces of the two cover slips, (2) the three-dimensional network is composed of junctions for forming the two-dimensional networks, chains for connecting two adjacent junctions, and pillars connecting the two-dimensional network on one cover-slip surface to the other, and (3) the chains are made of bundles of stretched lambda DNA molecules, and the junctions and the pillars are made of the aggregates of DNA–histone complexes.