[Changes in the activity of different forms of RNA polymerase in the rat brain during postnatal development].

The dynamics of various forms of RNA-polymerases of the rat's brain was studied in the course of postnatal development, using autoradiography and fractionation of enzyme preparation purified from the matrix DNA admixture. In the brain of new-born rats, synthesis of ribosomal RNA proceeds more intensively, with form I enzyme being most active, due to a most active ribosomal RNA synthesis. As the brain develops, by the 12-14 days of life the activity of form I enzyme was found to decrease, whereas that of form II enzyme--to increase.