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G. A. Romanov V. Ya. Taran L. Chvojka O. N. Kulaeva 《Journal of Plant Growth Regulation》1988,7(1):1-17
Purified fractions of soluble proteins from barley leaves have been shown to contain specific binding sites fortrans-zeatin, a natural cytokinin. Such binding is very strong in vitro in concentrated solutions of some salts (ammonium sulfate or potassium phosphate) with optimum at pH 7–8 and temperature within the range 0–20°C. The cytokinin-binding sites have high affinity for zeatin (Kd1.5·10–8 M) and low capacity corresponding to 1–1.5 pmol zeatin per milligram of initial soluble protein. Cytokinin binding is reversible; it is due to protein (or proteins) with molecular weight 40–45 kDa. This protein(s) does not bind3H-adenine and3H-abscisic acid. The ability of various compounds to displace3H-zeatin from its high-affinity binding sites is in strict accordance with their biological cytokinin activities. Other phytohormones as well as fusicoccin do not displace3H-zeatin from its binding sites. Specific zeatin binding is sensitive to heat, alkali, and pronase, but not to RNase treatment. The 150- to 200-fold purification of cytokinin-binding proteins was achieved by a combination of ammonium sulfate precipitation and Ultrogel AcA-54- and DEAE-cellulose chromatography. The zeatin-binding protein(s) from barley leaves is suggested to take part in cytokinin action in vivo. 相似文献
3.
TheRhizobium tropici strain CFN 299 was maintained on PY medium and was grown in minimal medium (MM) with sucrose, glucose, fructose and glutamate (or their combination) as carbon sources. Bacteria were able to simultaneously use different carbon sources and, with a combination sucrose and glutamate, the growth rate was faster than with either carbon source alone. Sucrose transport was induced by sucrose and partially repressed by glucose and glutamate if they were included in MM as additional carbon sources. The transport of sucrose was active because both an uncoupler (dinitrophenol, DNP) and inhibitors of terminal oxidation (KCN, NaN3) severely reduced sucrose uptake. Sucrose transport was also sensitive to a functional sulfhydryl reagent but was much less sensitive to EDTA and arsenate. We obtained nonlinear Lineweaver-Burk plots for the uptake of sucrose (by sucrose-grown bacteria), and this implied the existence of at least two uptake mechanisms. Invertase (EC 3.2.1.26) is the main enzyme for sucrose hydrolysis in this organism. This enzyme was induced by sucrose and had high activity in mid-log phase cells when sucrose was the sole carbon source (0.2%). Invertase activity was not detected in growth medium. In general, the results obtained support the idea, thatR. tropici is adapted to sucrose utilization and to multicarbon nutrition during its interaction with plants. 相似文献
4.
L P Gorshunova V A Maksimova-Todorova V A Romanov K A Vanag A V Nabokova 《Biulleten' eksperimental'no? biologii i meditsiny》1978,85(5):567-569
Specific antigen was identified by the immunofluorescent test in the walls of the brain blood vessels, in the neurons, and in the glial cells of albino newborn mice and Syrian hamsters inoculated subcutaneously with 4 different batches of live measles vaccine. The pathomorphological test of the brain tissue revealed mainly vascular disturbances. The data obtained testify to the presence of residual neurotropism in the attenuated measles virus (strain "L-16"). 相似文献
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Experiments on white random-bred male mice were made to study the effect of L-thyroxine on cell proliferation of the hypotetraploid strain of Ehrlich's ascites carcinoma. It was shown that prolonged thyroxine administration (during 6 days of carcinoma growth) lead to synchronization of cell proliferation and the maximum values of the mitotic index was found 3 hours earlier then in the control experiments. At the same time thyroxine did not exert any noticeable effect on the average daily magnitudes of the number of DNA-synthesizing cells and did not change the pattern of modulations in the radioactive index. The changes in the mitotic index and radioactive index were asynchronous in control and experimental animals. Analogous results were found for hyperdiploid strain of Ehrlich's ascites tumor. Ploidy of cells did not influence the tipe rhythms of the cell proliferation and its reaction on the action of thyroxine. 相似文献
7.
Partially purified antichalone and chalone from the liver of the mammals possess significant antiradical activity revealed by the chemiluminiscent analysis in the system capable of generating free radicals. Chemiluminiscent damping degree is proportional to the quantity of antichalone and chalone in the system. During the first three days the activity of antichalone is increased, while that of chalone in decreased in the liver of partially hepatectomized rats. In 14 days after partial hepatectomy the activity of both antichalone and chalone decreased, but their ratio is normalized. Thus, the regeneration of the liver in different periods after the operation takes place when the condition of antichalone/chalone system in the organ is unequal. 相似文献
8.
Paul S Marley Aboubacar Toure Jay Shebayan DA Aba AO Toure AG Diallo 《Archives Of Phytopathology And Plant Protection》2013,46(1):29-34
Fourteen elite sorghum lines were evaluated for their resistance to Striga hermonthica at three locations in Nigeria and Mali. Results showed that many of the lines especially MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64 (Keninkédié) and the check SRN 39 remained resistant to Striga in all locations with low emerged Striga counts, while SAMSORG 14 had the highest Striga infestation in all locations. Considerable variation in reaction to Striga infestation was observed on Séguètana, 97-SB-F5DT-63 (Wasa), 97-SB-F5DT-65, CMDT 38, CMDT 39 and CMDT 45 which were susceptible to Striga at Samaru, Nigeria but were resistant to Striga at both locations in Mali. Based on low Striga resistance and high grain yield, lines MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64, 97-SB-F5DT-65, CMDT 39 and SAMSORT 14 have been nominated for wider evaluation across more West African countries. 相似文献
9.
Roni D. Gordon Wei Qiu Vladimir Romanov Kim Lam Maria Soloveychik Diana Benetteraj 《Journal of biomolecular structure & dynamics》2013,31(10):1057-1065
The nitrilases include a variety of enzymes with functional specificities of nitrilase, amidase, and hydrolase reactions. The crystal structure of the uncharacterized protein SA0302 from the pathogenic microorganism Staphylococcus aureus is solved at 1.7?Å resolution. The protein contains 261 amino acids and presents a four-layer αββα sandwich with a chain topology similar to that of a few known CN-hydrolase folds. In the crystal, the proteins are arranged as dimers whose monomers are related by a pseudo twofold rotation symmetry axis. Analysis of the sequences and structures of CN-hydrolases with known 3D structures shows that SA0302 definitely is a member of Branch 10 (Nit and NitFhit) of the nitrilase superfamily. Enzyme activities and substrate specificities of members of this branch are not yet characterized, in contrast to those of the members of Branches 1–9. Although the sequence identities between Branch 10 members are rather low, less than 30%, five conserved regions are common in this subfamily. Three of them contain functionally important catalytic residues, and the two other newly characterized ones are associated with crucial intramolecular and intermolecular interactions. Sequence homology of the area near the active site shows clearly that the catalytic triad of SA0302 is Glu41-Lys110-Cys146. We suggest also that the active site includes a fourth residue, the closely located Glu119. Despite an extensive similarity with other Nit-family structural folds, SA0302 displays an important difference. Protein loop 111–122, which follows the catalytic Lys110, is reduced to half the number of amino acids found in other Nit-family members. This leaves the active site fully accessible to solvent and substrates. We have identified conservative sequence motifs around the three core catalytic residues, which are inherent solely to Branch 10 of the nitrilase superfamily. On the basis of these new sequence fingerprints, 10 previously uncharacterized proteins also could be assigned to this hydrolase subfamily. An animated interactive 3D complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:19 相似文献
10.
Mikhail Yu. Steklov Sergey N. Lomin Dmitry I. Osolodkin Georgy A. Romanov 《Plant cell reports》2013,32(6):781-793
Cytokinins are ubiquitous plant hormones; their signal is perceived by sensor histidine kinases—cytokinin receptors. This review focuses on recent advances on cytokinin receptor structure, in particular sensing module and adjacent domains which play an important role in hormone recognition, signal transduction and receptor subcellular localization. Principles of cytokinin binding site organization and point mutations affecting signaling are discussed. To date, more than 100 putative cytokinin receptor genes from different plant species were revealed due to the total genome sequencing. This allowed us to employ an evolutionary and bioinformatics approaches to clarify some new aspects of receptor structure and function. Non-transmembrane areas adjacent to the ligand-binding CHASE domain were characterized in detail and new conserved protein motifs were recovered. Putative mechanisms for cytokinin-triggered receptor activation were suggested. 相似文献