Mutation induction in directly exposed cells is currently regarded as the main component of the genetic risk of ionizing radiation for humans. However, recent data on the transgenerational increases in mutation rates in the offspring of irradiated parents indicate that the genetic risk could be greater than predicted previously. Here, we have analysed transgenerational changes in mutation rates and DNA damage in the germline and somatic tissues of non-exposed first-generation offspring of irradiated inbred male CBA/Ca and BALB/c mice. Mutation rates at an expanded simple tandem repeat DNA locus and a proteincoding gene (hprt) were significantly elevated in both the germline (sperm) and somatic tissues of all the offspring of irradiated males. The transgenerational changes in mutation rates were attributed to the presence of a persistent subset of endogenous DNA lesions (double-and singlestrand breaks), measured by the phosphorylated form of histone H2AX (c-H2AX) and alkaline Comet assays. Such remarkable transgenerational destabilization of the F 1 genome may have important implications for cancer aetiology and genetic risk estimates. Our data also provide important clues on the still unknown mechanisms of radiation-induced genomic instability.

Pisum sativum (L.) plants were grown under "white" luminescent lamps, W [45 µmol(quantum) m -2 s -1 ] or under the same irradiation supplemented with narrow spectrum red light-emitting diodes (LEDs), RE [λ max = 660 nm, ∆λ = 20 nm, 40 µmol(quantum) m -2 s -1 ]. Significant differences in the chlorophyll (Chl) a fluorescence parameters, degree of State 1-State 2 transition, and the pigment-protein contents were found in plants grown under differing spectral composition. Addition of red LEDs to the "white light" resulted in higher effective quantum yield of photosystem 2 (PS2), i.e. F' v /F' m , linear electron transport (φ PS2 ), photochemical quenching (q P ), and lower non-photochemical quenching (q N as well as NPQ). The RE plants were characterised by higher degree State 1-State 2 transition, i.e. they were more effective in radiant energy utilisation. Judging from the data of "green" electrophoresis of Chl containing pigment-protein complexes of plants grown under various irradiation qualities, the percentage of Chl in photosystem 2 (PS2) reaction centre complexes in RE plants was higher and there was no difference in the total Chl bound with Chl-proteins of light-harvesting complexes (LHC2). Because the ratio between oligomeric and monomeric LHC2 forms was higher in RE plants, we suggest higher LHC2 stability in these ones.

Aim. To investigate structural and functional modifications of major components of photosynthetic membranes of endemic antarctic species D. antarctica under UV-B radiation. Methods. For quantitative determination of photosynthetic membrane components we used Arnon’s method (for chlorophylls and carotenoids); separation of carotenoids was carried out by Merzlyak’s method; polar lipids were isolated by Zill and Harmon method in modification of Yakovenko and Mihno; glycolipids separation and identification we carried out by Yamamoto method; and sulfoquinovosyl diacylglycerol content was determined by Kean method. The separation, disintegration and determination of pigment-protein complexes of chloroplasts were carried out by Anderson method. Authenticity of differences between the mean arithmetic values of indices was set after the Student criterion. Differences were considered as reliable at p 0.05. Results. We determined structural and functional changes in lipids, carotenoids and pigment-protein complexes at the photosyntetic apparatus level in D. antarctica plants under UV-B radiation. Conclusions. Adaptation of D. antarctica plants to UV-B radiation is accompanied by a cascade of physiological and biochemical rearrangements at the level of photosynthetic apparatus, manifested as the changes in pigment, lipid and pigment-protein complexes conten

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