[Dependence of the chromatin condensation process on the temperature and ionic strength of the media: investigation using gel electrophoresis in low density agarose].

Conformational mobility of 30 nm nucleosomal fiber under temperature variations at different ionic strength of the medium has been analyzed. A new property of chromatin organization has been characterized, namely, nucleosomal solenoid condensation in response to increase of temperature. This property is analogous to salt-induced condensation and becomes particularly prominent at low ionic strength. In this context previously obtained data on changes in the DNA linking number of topological domains are discussed. It is concluded that these changes probably arise from modification of supernucleosomal level of chromatin organization.