Dependence of the E. coli promoter strength and physical parameters upon the nucleotide sequence

The energy of interaction between complementary nucleotides in promoter sequences of E. coli was calculated and visualized. The graphic method for presentation of energy properties of promoter sequences was elaborated on. Data obtained indicated that energy distribution through the length of promoter sequence results in picture with minima at −35, −8 and +7 regions corresponding to areas with elevated AT (adenine-thymine) content. The most important difference from the random sequences area is related to −8. Four promoter groups and their energy properties were revealed. The promoters with minimal and maximal energy of interaction between complementary nucleotides have low strengths, the strongest promoters correspond to promoter clusters characterized by intermediate energy values

Response of exfoliated human buccal epithelium cells to combined gamma radiation, microwaves, and magnetic field exposure estimated by changes in chromatin condensation and cell membrane permeability

Modulation of the biological effects produced by ionizing radiation (IR) using microwave and magnetic fields has important theoretical and practical applications. Response of human buccal epithelium cells to different physical agents (single and combined exposure to 0.5–5 Gy γ-radiation (60Co); microwaves with the frequency of 36.64 GHz and power densities of 0.1 and 1 W/m2, and static magnetic field with the intensity of 25 mT) has been investigated. The stress response of the cells was evaluated by counting heterochromatin granules quantity (HGQ) in the cell nuclei stained with orcein. Membrane permeability was assessed by the percentage of cells stained with indigocarmine (cells with damaged membrane). The increase of heterochromatin granules quantity (HGQ), i.e. chromatin condensation was detected at the doses of 2 Gy and higher. Changes in the cell membrane permeability to indigocarmine expressed the threshold effect. Membrane permeability reached the threshold at the doses of 2–3 Gy for the cells of different donors and did not change with the increase of the dose of γ-radiation. Cells obtained from different donors revealed some individual peculiarities in their reaction to γ-radiation. The static magnetic field and microwaves applied before or after γ-radiation decreased its impact, as revealed by means of HGQ assessment