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71.
Mestechkina NM Shcherbukhin VD Bannikova GE Varlamov VP Drozd NN Tolstenkov AS Makarov VA Tikhonov VE 《Prikladnaia biokhimiia i mikrobiologiia》2008,44(1):111-116
Galactomannan from seeds of Cyamopsis tetragonoloba (L.) Taub. (guar) was depolymerized using immobilized enzymatic preparation celloviridin. A set of fragments whose molecular weights varied from 12.6 to 245.6 kDa was obtained. Sulfated derivatives of components of all fractions were synthesized, in which the content of HSO3(-) groups was 48.05% +/- 2.31. All preparations exhibited anticoagulant activity, which was recorded in vitro in two tests--aIIa and aXa. The antithrombin activity (aIIa) was high (up to 65-87 U/mg) and did not depend on the molecular weight of a sulfated derivative; in the second test (aXa), the effect of molecular weight was observed. Biospecific electrophoresis allowed us to detect the ability of galactomannan sulfates to form complexes with protamine sulfate, a classic antidote to heparin. 相似文献
72.
A model of time-delay recurrently coupled spatially segregated neural assemblies is here proposed. We show that it operates
like some of the hierarchical architectures of the brain. Each assembly is a neural network with no delay in the local couplings
between the units. The delay appears in the long range feedforward and feedback inter-assemblies communications. Bifurcation
analysis of a simple four-units system in the autonomous case shows the richness of the dynamical behaviors in a biophysically
plausible parameter region. We find oscillatory multistability, hysteresis, and stability switches of the rest state provoked
by the time delay. Then we investigate the spatio-temporal patterns of bifurcating periodic solutions by using the symmetric
local Hopf bifurcation theory of delay differential equations and derive the equation describing the flow on the center manifold
that enables us determining the direction of Hopf bifurcations and stability of the bifurcating periodic orbits. We also discuss
computational properties of the system due to the delay when an external drive of the network mimicks external sensory input. 相似文献
73.
N. N. Pozdnyakova S. V. Nikiforova O. E. Makarov O. V. Turkovskaya 《Applied Biochemistry and Microbiology》2011,47(5):543-548
The effect of polycyclic aromatic hydrocarbons (PAHs) on the time course of laccase production by the fungus Pleurotus ostreatus D1 under conditions of submerged cultivation on Kirk’s medium has been studied. It has been shown that phenanthrene, fluoranthene,
pyrene, and chrysene actively induce this enzyme, whereas fluorene and anthracene had a smaller effect. Addition of Mn2+ ions to cultivation medium elevates the laccase activity twofold and more in the presence of all the studied PAHs. Electrophoresis
under nondenaturing conditions demonstrates induction of additional laccase forms by xenobiotics. Ligninolytic peroxidase
activities are undetectable under the conditions used. 相似文献
74.
Vladimir G. Onipchenko Alii M. Kipkeev Mikhail I. Makarov Anna D. Kozhevnikova Victor B. Ivanov Nadejda A. Soudzilovskaia Dzhamal K. Tekeev Fatima S. Salpagarova Marinus J. A. Werger Johannes H. C. Cornelissen 《Ecological Research》2014,29(4):529-534
Snow roots are specialized structures recently discovered in the Caucasian alpine snow-bed plant Corydalis conorhiza. They form extensive networks that grow into snow packs against gravity, most probably to gather nitrogen from snow. Here we test the hypothesis that snow roots are true winter organs, i.e., they should already start growth early in winter to lay down the infrastructure for N capture from snow packs well before their melt-out. This would require winter surface and soil temperatures continuously close to or above freezing. Excavations of snow roots from snow packs in January and May, accompanied by temperature recordings and anatomical observations, supported our hypothesis. These findings complete the annual cycle of snow root phenology. They also emphasize the evolutionary and ecological significance of these specialized winter organs. Moreover, their likely association with a particular abiotic temperature and snow regime will facilitate the search for snow roots in other species. 相似文献
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77.
Alekseenko SV Toporova SN Makarov FN 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2002,88(3):324-328
Single cortical columns of areas 17, 18 in the cat were microiontophoretically injected with horseradish peroxidase. Spatial and laminar distributions of retrogradell labelled cells in both areas were investigated. Following injections in area 17 or in area 18 the labelled cells' region in area 17 was elongated (in a tangential plane) along the representation of visual field horizontal meridian. However the labelled cells' region in area 18 was elongated along the representation of vertical meridian. Such projection patterns appear to be common in these cortical areas throughout the central 10 degrees on various elevations (from -40 degrees to +10 degrees) of the visual field representation. Thus the spatial arrangement of intrinsic and extrinsic connections in each area coincides, at the same time in area 17 they are orthogonal to area 18. The following visual information exchange scheme may be suggested. Area 17 may supply the area 18 with more detailed information on the horizontal component of the visual image, and in the opposite direction the information on the vertical component of the same image may be supplied. 相似文献
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The characteristics and the possible mechanisms of action of cytotoxic ribonucleases (RNases), promising antitumor drugs, are described. Original experimental data and the results of analysis of recent publications have made it possible to identify the cellular components providing for the selective effects of exogenous RNases on tumor cells, on the one hand, and to estimate the contributions of individual molecular determinants to the enzyme cytotoxicity, on the other hand. The predominant effect of the electric charge of the RNase molecule on the induction of cell death has been demonstrated. The cytotoxic effects of RNases are determined by the catalytic cleavage of accessible RNA, the action of the products of its hydrolysis, and the noncatalytic electrostatic interaction of the exogenous enzyme with cell components. Potential RNase targets in a tumor cell and the role of modulation of calcium-dependent potassium channels and the ras oncogene in RNase-induced cell damage are considered. The effect of cytotoxic RNases on gene expression by affecting RNA interference is discussed.Translated from Molekulyarnaya Biologiya, Vol. 39, No. 1, 2005, pp. 3–13.Original Russian Text Copyright © 2005 by Ilinskaya, Makarov. 相似文献
80.