[Accumulation of magnetic nanoparticles in plants grown on soils of Apsheron peninsula].

The disclosure of magnetic nanoparticles in five plant species growing in Apsheron peninsula have been detected by the EPR method. The EPR spectra of these nanoparticles proved to be similar to those of synthesized magnetic nanoparticles. The result demonstrated that plants are capable of absorbing magnetic nanoparticles from the soil. The accumulation of nanoparticles in plants is confirmed by the presence of a broad EPR signal whose maximum position of the low-field component changes from g = 2.38 and halfwidth of the signal of 32 mT at room temperature to g = 2.71 and 50-55 mT at 80 K. The intensity of the broad EPR signal for plants grown in radioactively contaminated areas (170-220 mkR per h) was substantially lower compared with plants grown on clean soil. The parameters of the broad EPR signal and its dependence on the temperature of recording were identical with those for synthetic magnetic nanoparticles. The photosynthetic activity and changes in the genome of irradiated plants by the analysis of PCR products were studied.

Two types of kinetics of membrane potential of water plant leaves illuminated by ultraviolet light.

The effects of ultraviolet-B (UV-B) radiation on plasma membrane of water plant (Elodea canadensis, Vallisneria spiralis) cells were investigated by using microelectrode methods. A fast and reversible depolarization of membrane potential occurs initially during exposure of leaf cells to UV on a white light background, after which a slow phase of depolarization sets in. On action series, UV is pulsed for 15 s, with dark interval of 3 min, no monotonous response of systems on the UV excitation is observed. The action spectrum of the fast UV response lies in the interval of 300-330 nm and that of the slow phase-in the interval of 280-300 nm. The input impedance of membranes remains unchanged during the period of exposure. It is concluded that the H(+)-extruding complex of plant cell plasma membranes really consists of two types of interrelated electronic H(+)-pumps: an H(+)-pump of redox-active nature and the H(+)-pump of the H(+)-ATPase enzyme complex. Clearly, during the exposure of leaf cells to UV light, initially, the H(+)-pump of redox-active nature and then H(+)-ATPase are inhibited. It is proposed that the initial chromophore of UV-B light on plasma membrane can be one of the components of H(+)-pump of redox-active nature. It is probably the molecular of quinone.

[Structural organization of rimorphin and its synthetic analogs]. / Strukturnaia organizatsiia rimorfina i ego sinteticheskikh analogov.

The spatial structure and conformations of rimorphin were investigated using theoretical conformational analysis. The spatial organization of the peptide can be described by a set of 11 low-energy conformations of the backbone. By solving the reverse conformational problem, a number of modified amino acid sequences ([Ala2], [Ala3], [MePhe9], [MeLys10], [MeVal11], and [MeVal12]-analogs of rimorphin) were determined that have spatial structures corresponding to the set of low-energy conformations and should, therefore, possess physiological activity.

[Light-dependent paramagnetic center in photosystem 2 of higher plants]. / Svetozavisimyi paramagnitnyi tsentr v fotosisteme 2 vysshikh rastenii.

In subchloroplast fragments of photosystem II from Vicia faba, free from P700 contamination, a free-radical ESR signal (singlet of 9 G peak-to-peak line-width, g approximately 2,0025) appears under illumination in presence of silicomolybdate as electron acceptor. Using ESR-active electron donors and acceptors as well as conventional redox reagents Hill activity of preparations has been evaluated under different conditions. Evidences are presented that the light-induced dark-reversible silicomolybdate-dependent ESR signal is of the same origin as photobleaching centered at 680 nm which has been earlier interpreted as a result of P680 center of photosystem II oxydation. The relaxation properties of this paramagnetic center as measured by microwave power saturation are different from that of P700+-center in photosystem I.

[Molar extinction of pigment in the reaction center of photosystem II chloroplasts]. / Moliarnaia ékstinktsiia pigmenta v reaktsionnom tsentre fotosistemy II khloroplastov.

The absolute spin number in the Photosystem I chloroplast fragments from Vicia faba plant photooxidized in the presence of silicomolybdate has been carefully measured by means of camparison of ESR signals of P680-centers and of nitroxyl free radical aqueous solution. The data obtained together with simultaneous measurement of light-induced bleaching centered at 680 nm have been used to determine the molar extinction of reduced P680-center epsilon680 = 0.66 . 10(5) M-1 cm-1.

[Reduction paths of reaction centers of photosystem I of photosynthesis]. / O putiakh vosstanovleniia reaktsionnykh tsentrov fotosistemy I fotosinteza

The behaviour of ESR signal I in blue-green algae and chloroplasts is considered under various illumination and with various previous treatment. It is shown that the main process determining the kinetics of P700 plus reduction is the reaction with reduced components of the electron transfer chain between the two photosystems. If the accumulation of the products is inhibited by any way, then the reduction rate depends on the reactions with reducing agents in the incubation medium accumulated under irradiation before experiment. These exogenic reducing agents may be removed from the chloroplasts with repeated washings, and from algae-by means of the dark incubation for a long time. The relation of cyclic and noncyclic electron transfer is considered with and without artificial cyclic flow mediator.