[The role of AmtB, GlnK and glutamine synthetase in regulation of transcription factor TnrA in Bacillus subtilis].

The nitrogen is a macroelement for all alive cells, from bacteria to animals. Although NH3/NH4+ are highly toxic to animal, they are the preferred source of nitrogen for the most microorganisms and are assimilated by glutamine synthetase in the GOGAT cycle. The nitrogen limitation triggers a number of regulatory processes and activates many genes, providing the utilizing of alternative nitrogen sources.

[Study of mutagenic activity of fullerene and some of its derivatives using His+ reversions of Salmonella typhimurium as an example].

The influence of three new derivatives of fullerence C60 ([61]dimethoxyphosphoryl[61]carbethoxy-methano[60]fullerene, [61]-(dimethoxyphosphoryl-[61]-carbmethoxy-methanofullerene, and 1-methyl-2-(3,5-di-tertbutyl-4-hydroxy-phenyl)-3,4-fulleropyrrolidine) on the appearance of His+ reversions in the Salmonella typhimurium strain BA13 was studied. It was ascertained that the effect of fullerene derivatives on the occurrence of mutations depends on the type of the molecular group with which fullerene interacts. The biological effect is determined not only by the action of the group associated with fullerene.

Purine receptor agonists protect the genome of plant and animal cells from clastogen damage.

Purine receptor agonists adenosine, cyclohexyladenosine, phenylisopropyladenosine, dimethylaminopurine riboside, ATP, and ADP reduced the level of chromosome aberrations and the number of micronuclei induced by ethylmethane sulfonate and cyclophosphamide in plants (Crepis capillaris) and mice. Possible mechanisms of the protective effect of these ligands are discussed.

[Phenotypic characterization of Bacillus subtilis mutants with decreased exonuclease I activity].

A Bacillus subtilis strain containing a mutation decreasing exonuclease I activity by up to 25% as compared to normal cells of the original BD46 strain was developed. A decrease in B. subtilis exonuclease I activity increased the sensitivity of mutant cells to UV irradiation and mitomycin C, decreased the frequency of recombination during chromosomal transduction and transformation, decreased the frequency of transposon Tn917 translocation from plasmid to the bacterial chromosome, and did not affect the frequency of plasmid transformation.