Fragmentation of 'nuclear matrix' on a mica target.

Chromatin depleted nuclei ('nuclear matrix') of Ehrlich ascites cells were characterized and fragmented by glycerol shot technique (particle fragmentation). The preparations reveal that 'nuclear matrix' is entirely composed of granules and fibres. Prominent size classes of granules are 10 to 20 nm and 25 to 40 nm, respectively. Most of the granules remain attached to fibres during the fragmentation process. The diameter of the fibres corresponds with double-stranded DNA visualized under identical conditions. The RNP-like nature of the particles is shown by their proteinase K/RNase sensitivity. Since the 'nuclear matrix' architecture becomes instable in high salt buffer after pretreatment with RNase which changes the RNP-particle-like material it must be inferred that the RNP/DNA interaction is a prerequisite for the high salt stability of the 'nuclear matrix' complex.