[Influence of abscisic acid and fluridone on the content of phytohormones and polyamines and the level of oxidative stress in plants of Mesembryanthemum crystallinum L. under salinity]

The effect of abscisic acid (ABA) and fluridone on the content of endogenous phytohormones and free polyamines and the intensity of oxidative stress was studied in plants of Mesembryanthemum crystallinum L. under salinity. It was shown that the pretreatment of plant roots with 1 μM ABA, followed by the action of 300 mM NaCl, caused a protective effect and improved the physiological state of the plants, which was manifested in increased biomass and content of available cytokinins and reduced values of the indicators of oxidative stress. It was noted that the inhibitor fluridone reduced the effect of ABA and acted as a pro-oxidant.

Nickel accumulation in rape shoots (Brassica napus L.) increased by putrescine

Application of exogenous putrescine (Put) increases nickel accumulation in rape shoots (Brassica napus), improving potential for phytoremediation of contaminated soils. Plants were grown within a growth chamber in water culture for five weeks, then 250-500 microM NiCl2 was added to rooting media. Within 5 days of treatment, damaging effects of nickel manifested as a reduction of root system size and a decrease of Cu and especially Fe content in young leaves. Spraying leaves of adult plants with Put markedly reduced toxic effects of Ni on root growth, enhanced leaf supply with Fe, and increased Ni content in young leaves by 2.5 times. Plant growth in medium with elevated levels of Ni stimulated accumulation of endogenous spermidine (Spd), spermine (Spm), and especially Put (by 4 times as compared with the control). Results suggest that Ni-induced accumulation of endogenous polyamines in rape leaves is caused by activation of long-distance metal transport within the plant and reduction of its toxicity due to Put chelating action.

Exogenous cadaverine induces oxidative burst and reduces cadaverine conjugate content in the common ice plant

The effect of free cadaverine (Cad) on its conjugates formation was analyzed in roots of the common ice plants (Mesembryanthemum crystallinum L.). It was found for the first time that Cad could induce oxidative burst in the roots of adult plants, as was evident from the sharp decrease in the content of Cad soluble or insoluble conjugates. This unusual effect was associated with the increased oxidative degradation of exogenous Cad (1mM, 1.5h) and intense H(2)O(2) production in the root cells of adult plants. Root treatment of both juvenile and adult plants with H(2)O(2) (1mM, 1.5h) reduced the content of soluble Cad conjugates and increased the content of their components, free Cad and phenols. We also found that one of the possible reasons of the negative effect of exogenous diamine on the formation of conjugated forms in adult roots was alkalization of the root apoplast at Cad addition to nutrient medium and the unusual O(2)(-) synthase function as a pH-dependent guaiacol peroxidase in the presence of a high content of H(2)O(2). This was confirmed by the data on the accumulation of O(2)(-) and enhanced superoxide dismutase activity in adult roots under treatment with Cad. It is possible that the accumulation of O(2)(-) together with H(2)O(2) was also responsible for oxidative burst, which induced a decrease in the content of Cad conjugates in adult roots of the common ice plants.

The "clinic" medical-dosimetric database of Mayak production association workers: structure, characteristics and prospects of utilization

To study early (deterministic) and long-term effects of radiation exposure, the "Clinic" medical-dosimetric database for the Mayak Production Association worker cohort has been established at the Southern Urals Biophysics Institute (SUBI). This paper describes the principles of organization, structure and prospects of future utilization of this database.