[The bounds of the riboflavin operon in Bacillus subtilis].

All the structural genes of riboflavin biosynthesis are shown to be located on the 2.8 MD DNA fragment, using the collection of plasmids, carrying the Bacillus subtilis riboflavin operon fragments and Bacillus subtilis strains, containing various deletions of rib-operon for analysis. The proximal Bgl II site is shown to be located between promoter P1 and the first structural gene ribG.

[Disorder of the repair of DNA double-stranded breaks in radiosensitive mutants of Saccharomyces cerevisiae yeasts].

DNA double-strand break repair and restoration of viability in X-irradiated diploid yeast cells homozygous for rad50, rad51, rad52, rad55 mutations were studies under conditions of keeping the cells in non-nutrient medium, after irradiation. All the cells were synchronized at the G1 stage of the cell cycle. In contrast to the wild-type yeast, this group of mutants are unable to repair DNA double-strand breaks and do not enhance viability, when kept in non-nutrient medium after irradiation.

[Stability and the biodestruction of polymer compositions for joining and replacing bone tissue].

Ethylcyanacryl-based compositions were subjected to gravimetric studies with the use of standard specimens in numerous laboratory tests and in 60 experiments on rabbits. Compositions with various fillers were studied. A relatively high elimination rate or orotic acid, microcapsulated in dextrane, from polymerized blocks was found.