Adaptation to mountain γ-background: bacteria speciation.

PURPOSE: To study the adaptation of bacteria to the natural γ-background of mountains and anthropogenic emissions from nuclear power plants; to establish the main factors of variability and speciation of bacteria. METHOD: Analysis of materials on the radiation background and its impact on living organisms in the landscape of Armenia, calculation of the absorbed dose by microbes due to rock radiation. RESULTS: The review shows the death, reproduction, radioresistance and speciation of bacteria in changing conditions of low variable natural and anthropogenic γ-background. CONCLUSION: We assume that γ-rays from rocks activate cellular epigenetic mechanisms that regulate genome expression, signaling and, ultimately, variability of bacteria. Some of them have already been studied, others require research.

Hybridization kinetics of DNA fragments in the presence of ligands intercalating into DNA-duplexes.

In this work the hybridization kinetics of DNA fragments on underlayer has been studied, when besides single-stranded DNA molecules there are also ligands in the medium that are able to intercalate into DNA-duplexes. A system of differential equations was obtained that describes the correlative change of the number of DNA-duplexes on the underlayer and the change of the number of ligands intercalating into DNA-duplexes. It was shown that the rate of underlayer filling by DNA-duplexes increases along with the enhancement of both equilibrium constant of formation reaction of DNA-duplexes and the concentration of DNA targets in the solution. It was also shown that the intercalation kinetics of ligands into DNA-duplexes relevantly depends on relation of dissociation rate constant of DNA-duplex to dissociation rate of the ligand complex with DNA-duplex.Communicated by Ramaswamy H. Sarma.

Adsorption of ligands on macromolecules in the fluctuating medium.

In the present work fluctuations of number of ligands adsorbed on macromolecule are investigated. We have taken into account the adsorption and desorption of ligands under the circumstance of some adsorption centers fluctuations affected by medium fluctuation. The correlation function and spectral density of number of ligands adsorbed on macromolecule are calculated. The properties of these fluctuations which allow identifying a noisemaker are determined. It has been shown, thatfas andsluggis adsorption can be distinguished by properties of dispersion and spectral density. It has been also shown, that comparison of experimental and theoretical correlation functions (or spectral densities) allows to calculate constants of ligand - adsorption center binding and unbinding.

Kinetics of adsorption of extended ligands on DNA at small fillings.

In the present work, the adsorption kinetics of extended ligands on DNA duplexes at small fillings when molecules of DNA duplexes are on the underlayer within diffusion layer has been investigated. Both diffusion of ligands in solution (diffusion stage) and adsorption of ligands (kinetic stage) are taken into consideration at adsorption of ligands on DNA duplexes. Nonlinear system of differential equations describing adsorption of ligands where not only diffusion stage but also kinetic stage is taken into account, is obtained, moreover the equations allow localizing duplexes in arbitrary place within diffusion layer. Numeric solution of the equations makes possible to investigate the filling kinetics of DNA duplexes by ligands depending on parameters controlling adsorption process. It has been shown that depending on relation between adsorption parameters different kinetic regimes of adsorption - kinetic, complex, and diffusion regimes may be realized.