[Effect of antioxidant-ambiol on the radiation adaptive response].

For studying of the mechanism of adaptive response of plants the seeds of soft wheat Triticum aestivum cultivar Moscovskaya 39 were irradiated in doses 0.25, 50 and 0.25 + 50 Gy and the frequency of cells with aberrations and the mitotic activity in the meristem of seedlings were scored. The pre- and post-treatments of seeds with antioxidant--ambiol were also used. It was found that the exposure of seeds to 0.25 Gy reduce the effects of challenge dose of 50 Gy: the mitotic index increases and the frequency of cells with aberrations decreases--the adaptive response appear. It was also found that the pretreatment with ambiol reduce the effects of the irradiation in the dose of 50 Gy. Post-treatment was less efficiently. Both treatments raise the adaptive response. The correlation between the frequency of aberrant cells and the mitotic index was found and, regardless of the type of treatment all points of experiment fall on the common regression line with the regression coefficient -0.85 (p < 0.01). These facts serve as evidence (1) that the radioprotective effect by the pre- and post-treatment occurs by a common mechanism and (2) that the in the exhausted concentration antioxidant does not change the extent of genome damage inflicted by irradiation. The evidence is consistent with the hypothesis that a nonspecific inducible process of stimulated repopulation was a mechanism of adaptive response of plants.

[On antimutagenesis mechanism in plants].

The effect of nitrosylmethylurea (NMU) on the mitotic index and the frequency of cells with aberrations, as well as the effects of pre- and posttreatment with antioxidant ambiol on the NMU effects were studied on seedlings of common winter wheat Triticum aestivum, cultivar Moskovskaya 39. Both pre- and posttreatment with ambiol resulted in antimutagenic effect but after posttreatment, the effect was lower. Irrespective of type of seedling treatment with ambiol and the time of their fixation (45, 48, and 51 h), when mitotic index is plotted versus frequency of cells with aberrations, all experimental points fall on the same regression line with coefficient of correlation of -0.82 (P < 0.001). This implies that the same mechanism underlies antimutagenic effect irrespective of when the antimutagen was applied, before or after the knockout mutagen dose. This also suggests that the antimutagenic effect is independent of the degree of the mutagen-induced damage, because by the time of posttreatment, the volume of genome damage is already determined and the antimutagen fails to change it. Finally, this suggests that irrespective of time of antimutagen treatment, the mutation frequency is reduced by the mechanism of stimulated repopulation.

[Stimulated repopulation as a basis of antimutagenesis and the adaptive response in plants]. / Stimulirovannaia repopuliatsiia kak osnova fenomenov antimutageneza i adaptivnogo otveta u rastenii.

Wheat seeds were used to study (1) modification of the radiation adaptive response (AR) with antioxidant anphen and (2) modification of the clustogenic effect of N-methyl-N-nitrosourea (MNU) with various agents. Pretreatment with anphen enhanced AR. Each pretreatment (irradiation with 0.25 Gy, treatment with anphen, treatment with anphen followed by irradiation with 0.25 Gy) decreased aberration frequency. This parameter proved to be in a linear dependence with mitotic index (MI) with correlation coefficient -0.978; the regression line passed through the point corresponding to spontaneous MI and spontaneous aberration frequency. Upon treatment with MNU, the antimutagenic effect was observed for various pretreatments (a low concentration of MNU, antioxidant phenoxan, irradiation with 0.25 Gy). Again, MI and aberration frequency were in inverse proportion with correlation coefficient -0.99, and the regression line passed through the point with spontaneous MI and spontaneous aberration frequency. The same dependence was observed for previously published data on modification of radiation AR with phenoxan. The results were hard to explain in terms of the repair-associated mechanism of AR and the antimutagenic effect. Hence, a nonspecific inducible process of stimulated repopulation was assumed to be a common mechanism of AR and the antimutagenic effect in plants.

[Radiation adaptive response in wheat. Phenomenology and possible mechanism]. / Radiatsionnyi adaptivnyi otvet u pshenitsy. Fenomenologiia i veroiatnyi mekhanizm.

It was demonstrated that preliminary irradiation of wheat seeds with doses of 0.10 and 0.25 Gy reduced the sensitivity to the clastogenic action of the challenge doses of gamma-irradiation at 10 and 20 Gy, but not to a doses at 50 and 100 Gy. The adaptive response (AR) was observed. It was found that the pretreatment of seeds with antioxidant (anphen and phenoxan) before the adaptive irradiation increased the AR and revealed it after the challenge dose of 50 Gy. The formed AR was observed also on the following studies of the development of plants in particular in M1 and M2. The phenomenon is genetically determined. It has been established that the frequency of aberrant cells in each variant of the experiment (exposure of seeds to a challenge dose without pretreatment; with preliminary irradiation at a conditioning dose; pretreatment with antioxidant; treatment of seeds with antioxidant followed by exposure to conditioning doses and to a challenge doses) is in inverse proportion to the observed mitotic index and that in the experiment on the whole the frequency of aberrant cells has a linear relationship to the mitotic index with a correlation coefficient near-1, the regression line passing through the point corresponding to the spontaneous mitotic index and to the spontaneous frequency of cells with aberrations. Since the obtained results can hardly be explained in terms of the repair mechanisms of adaptive response, the authors assume that they suggest the existence of a common mechanism of formation of both an adaptive response and an antimutagenic effect in plants and that this mechanism functions as a nonspecific inducible process of stimulated repopulation.

[Effect of Agrobacterium tumefaciens (Smith and Town). Conn. on the functional properties of human blood lymphocytes]. / Vliianie Agrobacterium tumefaciens (Smith and Town). Comm. na funktsional'nye svoistva limfotsitov krovi cheloveka.

Agrobacterium tumefaciens has been shown to affect the proliferation of intact lymphocytes as well as lymphocytes stimulated by PHA action. Inoculation of bacteria into the cultures of intact lymphocytes and incubation during 72 h resulted in increased incorporation of [3H]-thymidine into the DNA of cultivated cells. The bacteria are capable of inhibition of lymphocytes proliferation stimulated by PHA.

[Physicochemical changes in DNA and deoxyribonucleoprotein caused by potassium cyanate]. / Fiziko-khimicheskie izmeneniia v DNK i dezoksiribonukleoproteide, vyzyvaemye tsianatom kaliia

The influence of KNCO on the structural integrity of the DNP salt solutions was studied. By the methods of sedimentation, viscosimetry, spectrophotometry and circular dichroism it was shown that KNCO failed to induce degrading the polynucleotide DNA strands and weakened the bonds between the DNA and protein.