[Effect of mutations in the uvrA and recA genes on the photoreactivity of Escherichia coli cells irradiated by UV light (250 and 313 nm)]. / Vliianie mutatsii v genakh uvraA i recA na fotoreaktiviruemost' kletok Escherichia coli, obluchennykh UF-svetom (250 i 313 nm).

The relative contribution of photo- and non-photoreactivable damages to the lethal effect of far-(250 nm) and mid-(313 nm) wave UV in isogenic bacterial cells Escherichia coli WP2 (wild type, uvrA and recA mutants) was estimated. It has been demonstrated that the value of non-photoreactivable damages increases with lambda of UV (250----313 nm) and depends on the genotype (uvrA and recA).

[Spectrum of formation of photo- and non-photoreactivated damage in E. coli cells irradiated with UV light (250-334 nm)]. / Spektr obrazovaniia foto- i nefotoreaktiviruemykh povrezhdenii u kletok E. coli, obluchennykh UF-svetom (250-334nm).

A relative contribution of photoreactivated (modified by visible light) and non-photoreactivated (modified by temperature) damages to UV-irradiated (250-334 nm) E. coli B cells was estimated. The contribution of damages modified by temperature to a lethal effect of UV-radiation was invariable within the range from 250 to 334 nm. The photoreactivation of E. coli B cells was also independent of lambda-inactivating UV-light within 250-313 nm, and its value exceeded that of the wild-type E. coli WP2 which did not vary by the mode of UV-damages repair. Moreover, in contrast to E. coli B. cells, the value of the photoreactivation of E. coli WP2 decreased, as lambda-inactivating UV-light increased from 250 to 313 nm.

[Combined effect of photoreactivation and temperature on the survival of cells from E. coli B, irradiated with short-wave UV light]. / Kombinirovannoe deistvie fotoreaktivatsii i temperatury na vyzhivaemost' kletok E. coli B, obluchennykh korotkovolnovym UF-svetom.

A study was made of the survival curves of E. coli B(fil+/lon-) exposed to far UV-light (lambda = 254 nm) plated immediately after liquid holding recovery and after photoreactivation and incubated overnight at 37 degrees and 42 degrees. It was shown that the survival rate was always higher at 42 degrees C irrespective of the modification technique applied. Since the temperature-induced modification was significant after complete elimination of pyrimidine dimers (PD) a conclusion was made that UV-light, in addition to PD, induced just one more type of damages modified by temperature.

[The oxygen effect in E. coli cells. Role of the photoreactivated component in modifying the oxygen effect in E. coli WP2 uvrA6 cells]. / Kislorodnyi éffekt u kletok E. coli. Rol' fotoreaktivuemogo komponenta v modifikatsii kislorodnogo éffekta u kletok E. coli WP2 uvr A6.

A study was made of a contribution of photoreactivated lesions to the oxygen effect (OE) manifestation in cells of UV-sensitive E. coli WP2 uvrA6. It was shown that the contribution of the photoreactivated lesions depends upon radiation energy and gas conditions in which radiation is delivered. The OE value in the uvrA6-mutant may be modified in the irradiation conditions preventing induction of the photoreactivated lesions (gamma-irradiation in the presence of nigrosine, and X-irradiation).

[Theoretical analysis of the effect of the photoreactivation of E. coli cells irradiated with gamma quanta]. / Teoreticheskii analiz éffekta fotoreaktivatsii kletok E. coli, obluchennykh gamma-kvantami.

The assumption that the formation of pyrimidine dimers in E. coli cells, placed in a transient aqueous medium exposed to gamma-quanta, is conditioned by Cerenkov radiation laid the basis for the development of a biophysical model to explain the photoreactivation effect observed. The dependence of the effect upon gamma-radiation energy and the volume of the exposed suspension is predicted and compared with experimental data.