[Comparative characteristics of the "ultrasonic" fractions of rabbit leukocyte (neutrophil) and brain chromatin].

Ratios and composition of "ultrasonic" fractions of chromatin in cells with different transcription intensity were studied. The hardly extracted residual fraction of chromatin makes up to about 80% DNA in leukocytes (neutrophils) and about 20% in brain tissue. Comparative characterization of fractions showed that residual DNP of brain and liver include, in addition to fragments of inactive condensed chromatin, the sites actively involved in the synthesis of RNA. The residual DNP of leukocytes, on the contrary, possesses a number of characteristics of inactive chromatin. A hypothesis is discussed of the necessity of close contacts between the most intensively transcribed RNAs and nuclear membrane lipid components, resulting in the incorporation of transcribed sites into the residual fraction.