[NaCl-induced photoinhibition and the recovery of the photosynthetic activity of katG- mutant of the cyanobacterium Synechocystis sp. PCC 6803].

The joint effects of 0.5 M NaCI and light of different intensities on the activity of the photosynthetic apparatus and ATP contents in cells of the katG- mutant of cyanobacterium Synechocystis sp. PCC 6803 have been studied.

[Orange-red light reduces the inhibition by UV-A of the proliferation of rat fibroblasts and influences their attachment in a dose-dependent fashion].

The effects of ultraviolet-A (UV-A, lambdam = 365 nm) and orange-red light (lambdam = 625 nm) on the attachment and proliferation of embryonic skin-muscle rat fibroblasts were investigated. It was found that orange-red light (ORL) produces both the stimulatory and inhibitory actions on the attachment and proliferation of fibroblasts, whereas UV-A radiation caused only the inhibition of the processes. Upon consecutive irradiation in both variants: ORL --> UV and UV --> ORL, the synergistic effect of the inhibitory action in both spectral regions was observed.

[Effect of oxidative stress inductors on the photosynthetic apparatus in cyanobacterium Synechocystis sp. PCC 6803 Prq20 mutant resistant to methyl viologen].

The damaging effect of oxidative stress inductors: methyl viologen, benzyl viologen, cumene hydroperoxide, H2O2, menadion, and high irradiance on the photosynthetic apparatus of cyanobacterium Synechocystis sp. PCC 6803 in cells of the wild type strain and the methyl viologen-resistant Prq20 mutant with the disrupted function of the regulatory gene prqR has been investigated by measuring the delayed fluorescence of chlorophyll a and the rate of CO2dependent -O2 gas exchange. It has been shown that the damage to the photosynthetic apparatus in the Prq20 mutant as compared with the wild type was less in the presence of methyl viologen and benzyl viologen.

[Low radiance in the region of wavelengths 620-660 nm reduces the UV-B-induced damage to photosystem II in spinach leaves].

The effect of monochromatic preirradiation in the region of wavelengths 550-730 nm on the parameters of variable and delayed fluorescence in primary spinach leaves irradiated with UV-B was investigated. It was shown that irradiation of leaves with UV-B at lambda(M) = 300 nm reduced photoinduced changes in variable and delayed fluorescence as well as increased the half rise-time of maximum fluorescence. Preirradiation in the region of 620-660 nm (I = 2-4 W x m(-2)) reduced partly the damage to photosystem II induced by UV-B, whereas preirradiation at lambda(m) = 550, 600, 700, and 730 nm had no significant influence.