[Effect of superhelical DNA on the transcription of cloned genes of the T4 phage].

The effect of DNA superhelicity on the transcription of T4 DNA fragments containing early genes uvs W, Y and late genes 25-29 was studied. RNA polymerase transcribes both early and late phage genes within the supercoiled recombinant plasmid. Late genes relative transcription increases essentially when T4-modified RNA polymerase is used.

[Temperature-sensitive mutant Escherichia coli for the B-subunit of DNA-gyrase. The effect on replication and transcription].

A temperature sensitive mutant affecting the B-subunit of DNA gyrase was isolated. The mutation leads to the thermolability of DNA gyrase in vitro and to the plasmid DNA relaxation in vitro. The immediate stop of the increase in mutant culture titre has been observed under nonpermissive conditions.

[Interactions of subunits of DNA gyrase].

Interaction of DNA gyrase A- and B-subunits during the process of DNA supercoiling was studied. For this purpose a E. coli Cour-1 mutant resistant to coumermycin and containing a mutation in the B-subunit of DNA gyrase was isolated and the influence of the DNA gyrase A-subunit specific inhibitor-nalidixic acid-on DNA supercoiling by wild-type and mutant enzymes was investigated.

DNA replication and transcription in a temperature-sensitive mutant of E. coli with a defective DNA gyrase B subunit.

A temperature-sensitive mutant of E. coli with a defective DNA gyrase B subunit has been obtained. The mutation is expressed in the thermolability of DNA gyrase in vitro and in DNA relaxation in vivo.

Changed properties of the A subunit in DNA gyrase with a B subunit mutation.

To investigate the interaction of subunits A and B of DNA gyrase during DNA supercoiling, a Cour mutant of Escherichia coli was obtained and the effect of nalidixic acid on the supercoiling of DNA by wild-type and mutant enzymes was assayed. The enzyme of the Cour strain proved to be more sensitive to nalidixic acid than the wild-type DNA gyrase. Hence the mutation affecting the B subunit can also change the properties of the A subunit, which fact suggests that the two subunits of DNA gyrase are in contact during DNA supercoiling.

[Effects of cycloheximide and chlorotetracycline on the activities of RNA-polymerases in mouse liver nuclei].

The activities of RNA-polymerases I and II in mouse liver nuclei isolated after injection of various poisons to mice were studied. An increased activity of RNA-polymerase I in the nuclei isolated from mouse liver after injection of the inhibitors of translation, i.e.

[Role of mitochondria in the process of steroidogenesis induced by gonadotropins].

Specific inhibitors of RNA and protein synthesis in mitochondria, ethidium bromide and chloramphenicol, suppress the increase in the uterine weight of sexually immature mice and the in vitro maturation of oocytes of anuran amphibians induced by gonadotropins. The effect of steroid hormones on the uterus of mice and the oocytes of amphibians is not prevented by the inhibitors of macromolecular syntheses in mitochondria. In in vivo experiments, the doses of ethidium bromide inhibiting RNA synthesis in the liver mitochondria of mice stimulate RNA synthesis in the nuclei.

[Characteristics of somatic cell hybrids (mouse X Chinese hamster) with ratios of chromosome sets different from the parent species. IV. An electrophoretic analysis of several enzymes of the dehydrogenase class].

Electrophoretic mobilities in polyacrylamide gel of five dehydrogenases: NADP-dependent malate dehydrogenase (NADP-MDH), 6-phosphogluconate dehydrogenase (6PGD), alcohol dehydrogenase (ADH), glucose-6-phosphate dehydrogenase (G6PD) and glutamate dehydrogenase (GDH) were investigated in a series of mouse X Chinese hamster somatic cell hybrids. Seven hybrid lines with different ratio of chromosome sets of hamster and mouse: 1 : 1, 2 : 1, 3 : 1 and 1 : 2 respectively were studied. NADP-MDH and 6PGD of both parental species and intermediate hybrid hands were present in all hybrids except two lines.

[Characteristics of somatic cell hybrids (mouse X Chinese hamster) with different ratios of parental species chromosome sets. IV. Electrophoretic analysis of several enzymes of the dehydrogenase class].

Electrophoretic mobilities in polyacrylamide gel of five dehydrogenases: NADP-dependent malate dehydrogenase (NADP-MDH), 6-phosphogluconate dehydrogenase (6PGD), alcohol dehydrogenase (ADH), glucose-6-phosphate dehydrogenase (G6PD) and glutamate dehydrogenase (GDH) were investigated in a series of mouse X Chinese hamster somatic cell hybrids. Seven hybrid lines with different ratio of chromosome sets of hamster and mouse: 1:1, 2:1, 3:1 and 1:2 respectively were studied. NADP-MDH and 6PGD of both parental species and intermediate hybrid bands were present in all hybrids except two lines.