[Changes in the activity of different forms of RNA polymerase in the rat brain during postnatal development]. / Izmenenie aktivnosti raznykh form RNK-polimerazy v golovnom mozge krysy v khode postnatal'nogo razvitiia.

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.

[Cytochrome oxidase of rat liver nuclear membranes and its interaction with mitochondrial cytochrome oxidase]. / Tsitokhromoksidaza iadernykh obolochek pecheni krysy i ee vzaimootnoshenie s mitokhondrial'noi tsitokhromoksidazoi

The percent of mitochondrial protein contamination in nuclei decreased 10-fold (from 18 to 1.8%) under purification of protein-labelled mitochondria before their introduction into nuclei-free homogenate, cytochromoxidase activity being unchanged. Thus, cytochromoxidase activity of nuclei does not correlate with the amount of nuclei-adsorbed mitochondrial protein, which demonstrates the presence of nuclear cytochromoxidase independent on mitochondrial protein. Radioactivity of protein-labelled mitochondria is proportially distributed between globuline, deoxyribonucleoprotein, acid and residual nuclear proteins, as it is shown under fractionation of nuclei isolated from protein-labeled mitochondria containing homogenate. The comparison of mitochondrial protein contamination of nuclear membranes and their possible contamination with cytochromoxidase and suecinate-cytochrome-c-reducatase activities revealed that cytochromoxidase activity of nuclear membranes is twice higher and succinate-cytochrome-c-reductase activity is considerably lower than it can be referred to mitochondrial protein contamination. The ratio of cytochrome-c-oxidase and succinate-cytochrome-c-reductase activities in isolated nuclear membranes is 4-7 times as high as that in mitochondrial membranes under the same isolation procedure. The data obtained make possible to consider the cytochromoxidase activity of nuclear membranes to be really nuclear enzyme, and not a contominant of nucleipreparation with mitochondrial membranes.