[Length of Meristematic and Fully Elongated Root Cells Related to Haploid DNA Content].

The lengths of meristematic (l(m)) and fully-elongated cells (l(e)) were measured in the roots of 118 monocot and dicot species of herbaceous plants from 20 angiosperm families. The results were analyzed using the data on haploid DNA content (C(val)) for the same species from the website (http://data.kew.org/cvalues). The distribution range of lm, le, and C(val) was wider in monocot plants compared to dicots. Values of l(m) and l(e) in monocot and lm in dicot species correlated positively with C(val). Dependence of lm and le on C(val) was similar in diploid and polyploid species, both monocots and dicots. The average length of root cells differed less than the root length.

[The role of ethylene in activation division cell quiescent center in the cut maize roots].

In the present work we used two maize cultivars in which root meristem responded differently to root tip excision: in Interkras-375 MW we observed meristem opening due to the activation of cell divisions in the quiescent center (QC), while in Krasnodar-194 MW the meristem remained closed. Excised root tips of Interkras M B-375 were shown to produce much more ethylene than excised root tips of Krasnodar-194 MW The inhibitor of ethylene biosynthesis L-α-ethoxyvinyl 2amino-glycine-HCl (AVG) and inhibitors of ethylene action AgNO3 and 1-methyl-cyclopropene (MCP) prevented meristem opening in excised root tips of Intekras-375 MW. The obtained results allow us to conclude that ethylene plays an important role in the activation of cell divisions in the QC of excised root tips.

[The strategy of emergency aid to patients with botulism].

This clinical observation demonstrates difficulty of differential diagnostics of botulism in a patient suspected to have acute pancreatitis and admitted to a multifield medical institution. Difficulties of interpretation of urgent clinical and instrumental examination are discussed. The therapeutic strategy is described.

[Activation of cell division in the quiescent center of excised maize root tip].

The phenomenon of activation of cell proliferation in the quiescent center of excised maize roots is described. The root tips were grown on wet filter paper in Petri dishes. This phenomenon was observed in 8 to 14 maize cultivars and was absent in excised Arabidopsis root tips. The distribution of mitoses in meristems greatly varied in roots of individual seedlings from the same seed lot and seedlings of different cultivars. Meristem opening was observed after the removal of small root tips not longer than 3 mm and intact seminal roots. Sucrose (2%) and 10(-6)-10(-8) M indole-3-acetic acid did not prevent meristem opening. These findings indicate that the state of quiescent center is maintained by a system of intercellular and interorgan relations, which are to be clarified.

[Nonspecific resistance in psychotropic agent poisoning complicated with pneumonias].

Nonspecific resistance was studied in patients in acute psychotic poisoning complicated with varying pneumonias. The indices obtained during long (120-min) blood incubation with an object of phagocytosis, namely phagocytic index, phagocytic number, bactericidity index, HCT test, and cytochemical activity index were shown to be of the highest informative value that characterizes the state of nonspecific mechanisms of immune protection. The diminished microphagocytic functional activity along with the severity of pneumonia was ascertained to result in the development of an inflammatory process.

Oxidative stress and formation and maintenance of root stem cells.

The hypothesis of L. Feldman and his coworkers, according to which a more oxidizing environment in the cells of root quiescent center results from high activity of ascorbate oxidase activated by indoleacetic acid (IAA) accumulating in these cells, is discussed. The high activity of ascorbate oxidase is responsible for lowered concentrations of the reduced form of ascorbic acid and glutathione and high content of reactive oxygen species in quiescent center cells. The oxidative stress represses proliferation of the cells. Inhibitors of IAA transport attenuate the oxidative stress, thus suggesting a role of IAA as an activator of ascorbate oxidase. Interestingly, the high concentration of IAA in dividing cap cells adjacent to the quiescent center cells did not cause retardation of cell proliferation and oxidative state in these cells.

[Stem cells in the root and the problem of stem cells in plants].

Plant cells are capable of reversible transition from the proliferating to the stem state. This transition is determined by a system of cell-cell interactions and interrelationships between plant parts. Stem cells defined as the cells preserving the capacity to divisions and differentiation for a long time arise repeatedly during development of the root and shoot primordial, rather than are clones of a population of stem cells laid down at a certain stage of embryogenesis. The quiescent center cells, rather than the surrounding actively dividing cells, best correspond to the characteristics of stem cells according to Loeffler and Potten. The factors that determine the quiescent center formation and maintenance in the root have been analyzed. The available data suggest that among these factors, indoleacetic acid transport and cap influence are of paramount significance. The cap formation precedes the quiescent center formation both during the root development and in the course of meristem regeneration after the root decapitation. The capacity of tem cell formation by the meristem suggests that not only meristem arises from the stem cells, but also that stem cells are formed from actively dividing cells. Repeated formation of stem cells allows long-term preservation of the capacity of plants for open morphogenesis and vegetative propagation.

Exposure to low-intensive superhigh frequency electromagnetic field as a factor of carcinogenesis in experimental animals.

Inbred albino mice and C57Bl/6 mice were exposed to nonthermal radiation of 37 GHz frequency in order to detect delayed effects caused by repeated irradiation. The detected pathomorphological changes and the dynamics of their formation suggest that these factors are responsible for delayed formation of immunodeficiency provoking mutagenic and carcinogenic effects.

Adaptation of plants to altered shoot orientation relative to the gravity vector.

Wheat Triticum aestivum L., carrots Daucus carota L., Chinese cabbage Brassica pekinensis Rupr., and African marigold Tagetes patula L. were grown at natural and inverted orientation in the Earth gravitational field. Light vector was set unidirectional or opposite directional relative to the gravity vector. Shoot orientation relative to the gravity vector was set natural or invert. Plants grew in the special pots furnished with plane or cylindrical hydrophilic porous membranes. The membrane allowed to stabilize a water potential in the root zone at the fixed level. Seeds were put into a fiber ion-exchange artificial soil overlaying horizontal hydrophilic plates of porous titanium or anchored to porous metal-ceramic tubes. Plants grew at the PPF level 550 +/- 20 micromoles/(m2 s) during 24-hr lighting and at the water potential level at the membrane surface (-1.00) +/- 0.08 kPa. Normal plants were obtained both at the natural and at the inverse shoot orientation in the all experiments. The wheat plants were yielded healthy germinating seeds no matter plant orientation. In the inverse orientation, no negative influence for plant biomass accruing was marked, but the increasing of shoot to root mass ratio was considerable. However carrot root crop mass decreasing was not revealed in the inverse orientation. The results demonstrated substantial dependence of morphological and physiological characteristics of higher plants on the gravity factor.

[The problem of stem cells in plants]. / Problema stvolovykh kletok u rastenii.

The uppermost cells of the root and shoot apical meristems are considered as stem cells. They are similar, in many features, to the stem cells of animals. But, unlike animals, the stem cells can repeatedly arise in plants during morphogenesis and regeneration or in tissue culture from actively dividing or differentiated cells. When the stem cells are removed, they can be repeatedly restored from the actively dividing cells. The maintenance of the population of stem cells is determined by interaction between the stem cells and actively dividing cells located below according to the feedback principle. The protein synthesized in the stem cells determines how the lower located cells affect the stem cells. Specificity of stem cell identification in plants is discussed.

Proton pumping in growing part of maize root: its correlation with 14-3-3 protein content and changes in response to osmotic stress.

The spatial pattern of mitotic activity, cell elongation, rate of H+ fluxes, and 14-3-3 protein content were determined in Zea mays roots. We found that the regions along the apical part of the growing root conversely differ in their proton pumping activity. Higher rate of H+ efflux coincides with higher growth rate and correlates with increased 14-3-3 protein content in membrane preparations. The segment consisting of the root cap and the apical part of the meristem exerts net inward proton pumping, which can be inverted under fusicoccin treatment or osmotic stress. In the latter case, this inversion is accompanied by accumulation of 14-3-3 protein in plasma membranes. The results obtained highlight 14-3-3 protein as an obvious candidate for the fine regulation of plasma membrane H+-ATPase in root apex.

[Differences in growth and ontogenetic development of plants grown in the Earth gravitational field in the natural and inverse orientation]. / Razlichiia v roste i ontogeneticheskom razvitii rastenii, vyrashchivaemykh v gravitatsionnom pole zemli pri estestvennoi i invertnoi orientatsii.

Wheat plants Triticum aestivum L., Apogee cultivar, were grown in the natural and inverse orientation of the Earth gravitational field. Special vegetation containers with double bottom were used for the cultivation. The upper bottom made of porous titanium served as a hydrophilic porous membrane stabilizing aquatic potential in the root-inhabited zone at a given level. Normal plants yielding viable seeds were obtained for both natural and inverse orientation. In our experiments, the inverse orientation induced dry weight accumulation by the plants as well as development of productive tillering shoots and increased the shoot-root dry weight ratio.

Cell cycle and its parameters in flowering plants.

Data on the duration of cell cycle and its phases in meristems are reviewed for 170 species from 93 genera of 38 families of higher plants. The reviewed cell cycle parameters are submitted in tabulated form, including taxonomic and anatomical characteristics of particular subjects, methods, experimental conditions, duration of cell cycle and its phases, and references. The influence of environmental factors on the cell cycle and temperature dependence of cell cycle parameters are considered in addition to certain features and causes of daily dynamics of mitotic index. Special attention is paid to the problem of comparability of different results of determination of cell cycle duration. As shown below, the only correct comparison of cell cycle parameters in different species is that, which is based on the evidence provided at species-specific optimum temperatures. A rather simple method for determining the optimum temperature of cell division and growth is based on the analysis of root growth rate. Critical temperature points are defined to serve for determination of optimum temperature for the cell cycle. As shown below, retardation of growth rate at low temperatures results from the proportional increase in the duration of cell cycle phases, while at the minimum temperature the morphological characteristics of meristem remain unchanged. Cell division anomalies or morphogenesis disruption that occur as cell cycle parameters change may be due presumably to the shock temperature action within the tolerant limits. Our experiments have suggested that the rhythm of illumination may exert essential influence on the parameters, structure and stationarity of the cell cycle.

[Analysis of possible mechanisms of regulation of root branching]. / Analiz vozmozhnykh mekhanizmov reguliatsii vetvleniia kornia.

The formation of lateral roots under the influence of growth inhibitors and phytohormons were studied with germs of corn and flax. All corn primordiums develop into the lateral roots without dormancy period, while some flax primordiums are delayed in development. Removal of root apical meristem (decapitation) does not result in the increase in number of lateral roots of corn germs. Decapitation of flax germs induces the development of some dormant primordiums, that leads to the considerable increase in number of lateral roots. Formation of additional primordium under decapitation does not take place. Auxin stimulates the formation of additional primordiums in flax, but does not effect the number of mature lateral roots. In corn germs synthetic auxin stimulates the development of additional primordiums in root zone, where primordiums are forming after the disturbance. It is shown that the time of primordium development does not change under inhibitor influence, if they do not selectively effect mitoses. It seems that auxins regulate initiation of pericycle division and formation of primordiums of lateral roots on the stage of development of meristematic protuberance. Cytokinins influence the development of already existed primordiums of lateral roots but do not effect the formation of new ones. Constancy of time of primordium formation and independence of their development on the state of the main root need future investigations. The authors suppose that regulation of these processes is non-hormonal.

[Variations in the size of mitotic cells in the root meristem]. / Variabel'nost' razmerov mitoticheskix kletok v meristeme kornia.

Variations in the length of mitotic and interphase cells were analyzed in various tissues of wheat roots and in the cortex of maize roots. Reliable differences were shown in the length of mitotic cells in individual files-clones of cells of the same tissue. The mean lengths of dividing cells in different roots differed to a lesser extent than those of different files in the same tissue of one root. Within the file, the length of sister simultaneously dividing cells differed the least, while the difference of lengths of neighbor simultaneously dividing nonsister cells was bigger. The mean length of interphase cells in any file was always less than that of mitotic cells by a factor of 1.45. This ratio was almost invariable for files and tissues in both plants we studied and corresponded to that of an exponentially growing cell population. In addition, a very small number of cells were found (less than 1%) in meristems, which are longer than the mitotic cells. The length of these cells exceeded those of mitotic cells by less than twice. The origin of such cells is discussed. The length of mitotic cells near the quiescent center is more variable than in the middle of the meristem in the cortex of both plants. In the meristem basal part, the mitotic cells were no longer than those in the middle of the meristem but there were no small dividing cells. In the wheat epidermis, the cells are differentiated into trichoblasts and atrichoblasts and, therefore, the length of dividing cells is highly variable. The cell length is essential for their transition to mitosis for all studied proliferating meristem cells.