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排序方式: 共有302条查询结果,搜索用时 46 毫秒
91.
92.
Dr. Michael A. Belenky Maya S. Konstantinova Andrey L. Polenov 《Cell and tissue research》1979,204(2):319-331
The proximal neurosecretory contact region (PNCR) of the lamprey, a homologue of the median eminence of tetrapods, was studied by light, fluorescence and electron microscopy. Paraldehyde fuchsin-positive neurosecretory fibers are seen mainly in the central part of the rostral subdivision of the PNCR. The Falck-Hillarp technique reveals a weak, mainly diffuse yellow-green fluorescence in the PNCR. The ultrastructure of the tanycyte layer of the PNCR is very similar to that in the neurohypophysis of the same species, although the funnel-shaped protrusions of the third ventricle in the rostral part of the PNCR are more frequent than in the neurophypophysis. Peptidergic A1 and A2 neurosecretory fibers are characterized by neurosecretory granules of 120-200 nm and 100-150 nm in diameter, respectively. Monoaminergic B type fibers contain granules 80-100 nm in diameter. Neurosecretory terminals and the vascular endfeet of tanycytes make contact with the basement membrane of the avascular connective tissue layer separating the PNCR from the hypophysial pars distalis. It is suggested that both peptide and monoamine neurohormones diffuse through the thick connective tissue septa into the underlying blood vessels which supply the pars distalis and thus affect the function of its glandular cells. 相似文献
93.
94.
K. V. Antonov I. D. Konstantinova A. I. Miroshnikov 《Nucleosides, nucleotides & nucleic acids》2013,32(1-3):153-159
Abstract A new approach to the synthesis of 2′,3′-dideoxyadenosine and 2′,3′-dideoxyinosine based on deoxygenation of 2′,3′-di-O-mesylnucleosides was developed. 相似文献
95.
M. A. Rosenfeld A. N. Shchegolikhin A. V. Bychkova V. B. Leonova M. I. Biryukova E. A. Kostanova M. L. Konstantinova 《Biochemistry. Biokhimii?a》2013,78(10):1171-1179
Ozone-induced oxidation of fibrinogen has been investigated. The conversion of oxidized fibrinogen to fibrin catalyzed either by thrombin or by a reptilase-like enzyme, ancistron, in both cases is accompanied by production of gels characterized by a higher weight/length ratio of fibrils in comparison with the native fibrin gels. IR spectra of the D and E fragments isolated from unoxidized and oxidized fibrinogen suggest a noticeable transformation of functional groups by oxidation. A decrease in content of N-H groups in the peptide backbone and in the number of C-H bonds in aromatic structures, as well as a decrease in the intensity of the C-H valence vibrations in aliphatic fragments CH2 and CH3 were found. The appearance in the differential spectra of the D fragments of rather intense peaks in the interval of 1200–800 cm?1 clearly indicates the interaction of ozone with amino acid residues of methionine, tryptophan, histidine, and phenylalanine. Comparison of the differential spectra for the D and E fragments suggests that fibrinogen fragment D is more sensitive to the oxidant action than fragment E. Using EPR spectroscopy, differences are found in the spectra of spin labels bound with degradation products of oxidized and unoxidized fibrinogen, the D and E fragments, caused by structural and dynamical modifications of the protein molecules in the areas of localization of the spin labels. The relationship between the molecular mechanism of oxidation of fibrinogen and its three-dimensional structure is discussed. 相似文献
96.
Microorganisms in a Disposal Site for Liquid Radioactive Wastes and Their Influence on Radionuclides
Tamara N. Nazina Evgenya A. Luk'yanova Elena V. Zakharova Larisa I. Konstantinova Stepan N. Kalmykov Andrei B. Poltaraus 《Geomicrobiology journal》2013,30(5):473-486
Deep subsurface horizons used for the disposal of liquid low- and intermediate-level radioactive wastes of the Siberian Chemical Complex (SCC, Russia) were studied by microbiological, radioisotope, and molecular biological methods. It was shown that a diverse microbial community inhabited the groundwater. The cell numbers of microorganisms of the major metabolic groups and the rates of sulfate reduction, denitrification, and methanogenesis in natural groundwater were low and increased in the zone of wastes dispersion. More than 40 strains belonging to the genera Kocuria, Microbacterium, Pseudomonas, Pantoea, Acinetobacter, Enterobacter, Klebsiella, Stenotrophomonas, Sphingomonas, Staphylococcus, Acidivorax, Shewanella, and Desulfosporosinus were isolated from the disposal sites. Among the isolates, the microorganisms were found that were able to concentrate actinides and other transuranium elements. Aerobic bacteria were able to sorb various radionuclides in laboratory experiments; however, biosorption was low in sample of groundwater and in carbonate solutions containing several radionuclides. Reduction of U(VI) by a sulfate-reducing enrichment culture from the site and reduction of U(VI) and Np(V) by an isolate Shewanella were observed in the presence of various organic substrates. These results show the necessity of further ecosystem characterization based on microbiological and radiochemical studies and modeling of biogeochemical processes at the deep disposal sites for liquid radioactive wastes. 相似文献
97.
E. Yu. Yuzbasheva T. V. Yuzbashev T. K. Konstantinova I. A. Laptev N. I. Perkovskaya S. P. Sineokii 《Applied Biochemistry and Microbiology》2011,47(8):744-753
The closest homologue of the Saccharomyces cerevisiae Flo1p cell wall protein was detected in Yarrowia lipolytica yeast (YALI0C09031p) by the method of genomic analysis, and capacity of its N- and C-domains to expose the Lip2 lipase on
the cell surface was studied. The efficient fixation of the enzyme on the Y. lipolytica cell wall surface was demonstrated. The activity of the cell-bound lipase was 9170 and 3200 units per 1 g of dry solid matter
when using N- and C-domains of the cell wall protein, respectively. At the same time, in the case of immobilization using
the N-domain, approximately 30% of the total lipase activity was detected in the culture medium, whereas when using C-domain
of the cell wall protein YALI0C09031p, practically all lipase was in the immobilized state. Obtained values of the level of
the cell-bound lipase activity considerably exceed previously published data opening a prospect for new technological solutions
which meet industrial needs. 相似文献
98.
Alternaria leaf spots of gerbera (Gerbera jamesonii H. Bolus ex J. D. Hook) were observed on plants from different greenhouses on commercial plants in Bulgaria. The symptoms of the disease on the leaves were characterized by the development of brown, small, scattered dots, which gradually enlarged and coalesced to form large, oval, circular or irregular, brown to black lesions with concentric rings. Affected plants showed lower vitality, suppressed development and fewer, smaller, distorted in shape flowers. Alternaria isolates, obtained from infected leaf tissues were grown in pure culture and the morphological characteristics of the colony and sporulation apparatus were determined. DNA, extracted from the fungal isolates was subjected to polymerase chain reaction (PCR) with primers ITS1/ITS4, amplifying the internal transcribed spacer (ITS) regions. The resulting products were sequenced and compared for homology with other species in the GeneBank. The isolates showed 94% homology of the ITS region with either Alternaria alternata, A. arborescens, A. tenuissima, A. longipes, A. lini or A. smyrnii. None of the studied isolates was amplified with the A. alternata specific primers AAF2/AAR3, indicating that they are pathogenic varieties of it or belong to another species. Pathogenicity tests on 10 gerbera cultivars revealed that all of them were susceptible to Alternaria leaf spot. Additional tests on nine other crops (Solanum lycopersicum, Calendula officinalis, Capsicum annuum, Celosia argantea, Pelargonium spp., Petunia hybrida, Nicotiana tabacum, Cucurbita moscata and Raphanus sativus var. radicina) and on tomato or pepper fruits, potato tubers and carrot roots also indicated that all tested plant species were potential hosts of the disease. This is the first report of highly virulent isolates of Alternaria spp. in Bulgaria that cause leaf spots on gerbera in greenhouses. 相似文献
99.
Tsimokha AS Mittenberg AG Evteeva IN Kulichkova VA Kozhukharova IV Ermolaeva IuB Konstantinova IM 《Tsitologiia》2007,49(7):552-560
The induction of apoptosis in K562 cells by doxorubicin (DR) was used as a model to investigate changes in the subunit composition, phosphorylation state and enzymatic activities of 26S proteasomes in cells undergoing the programmed death. Here we have shown for the first time that proteasomes isolated from the nuclei of control and induced K562 cells differ in their subunit patterns, as well as in the phosphorylation state of subunits on threonine and tyrosine residues. It has been shown for the first time that trypsin- and chymotrypsin-like, and the endoribonuclease activities of nuclear 26S proteasomes are affected under influence of DR on K562 cells. Treatment of K562 cells with DR leads to modification of zeta/alpha5 and iota/alpha6 proteasomal subunits associated with RNase activity of proteasomes. These findings confirm our hypothesis about so-called reprogramming of nuclear proteasomes population in undergoing apoptosis K562 cells which is manifested by changes in proteasomal composition, phosphorylation state, and enzymatic activities during the programmed cell death. 相似文献
100.