[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.

[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.

[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.

[Dependence of biological activity of triamine type platinum (II) complexes on their composition and structure]. / Zavisimost' biologicheskoi aktivnosti kompleksov platiny(II) triaminovogo tipa ot ikh sostava i stroeniia.

The growth-inhibiting effect on the roots of maize and cucumber shoots was studied. We tested 53 triamine complexes of platinum (cis*- and trans*-[Pt(NH3)*2LCl]Cl, cis*- and trans*-[PtHx*2LCl]Cl and [PtenLCl]Cl, where Hx is hydroxylamine, en is ethylenediamine, and L are various heterocycles, which either have biological activity and occur in the cells or have no biological activity and are foreign to the cells). The cis*-[Pt(NH3)*2LCl]Cl and [PtenLCl]Cl complexes showed cytostatic properties, and the latter were effective at higher concentrations. Small changes in the composition of ligand L led to marked changes in the biological activity of the complexes. In order to characterize the effect of the complexes, we first determined the time of development of the lateral root from its initial appearance to its divergence from the main root (Tlat). The complexes with cytostatic properties markedly inhibited root branching and increased Tlat. The other complexes had virtually no effect on Tlat and reduced the zone of lateral roots only at the expense of inhibition of the main root growth. The complexes with cytostatic properties markedly inhibited the main root growth with time. Parallel studies conducted in the Oncological Research Center, Russian Academy of Medical Sciences have shown that the complexes with cytostatic properties display distinct antitumor activity.

[The growth-inhibiting activity of mixed complexes of platinum(II) with ammonia and cycloalkylamines]. / Rostingibiruiushchaia aktivnost' smeshannykh kompleksov platiny(II) s ammiakom i tsikloalkilaminami.

The effect was studied of mixed cys- and 3-, 4-, 5-, 6-nomial cycloalkylamines or substituted 2-, 3-, 4-methyl- and 4-hydroxycyclohexylamines as well as similar carboxylatocomplexes containing anions of malonic hydroxymalonic, succinic and malic acids on the growth of corn sprout roots. Complexes with non-substituted cycloalkylamines possessed the most pronounced cytostatic activity. Complexes with substituted cyclohexylamines were less active than their non-substituted analogue as well as other complexes with lesser size of cyclic substitute. The cytostatic activity of carboxylatocomplexes, as compared to that of chlorocomplexes, generally manifested itself at ten times higher concentraiton and depended not only on the size of cycloalkylamine but also on the nature of acidoligand.

[The biological activity of platinum and methionine complexes: the antitumor action and inhibition of root growth by complexes of differing compositions and structures]. / Biologicheskaia aktivnost' kompleksov platiny s metioninom: protivoophukholevoe deistvie i ingibirovanie rosta kornei kompleksami raznogo sostava i struktury.

The effect of 21 methionine-platinum(II) and (IV) complexes on growth and division of cells in maize seedling roots has been studied. The studied complexes did not possess properties inherent in typical cytostatic compounds, e.g. cis-dichlorodiammineplatinum (DDP). They inhibited root growth at higher concentrations as compared to DDP. In contrast to DDP, the studied complexes inhibited cell elongation to a similar or greater extent than cell division, did not prevent lateral root formation, and their inhibitory effect did not change with time. No correlation between the level of tumor growth inhibition and the pattern of root growth was observed.