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排序方式: 共有186条查询结果,搜索用时 15 毫秒
1.
I L Kuz'mina A A Timofeev S V Germanov L V Levchenko M A Kulish 《Biulleten' eksperimental'no? biologii i meditsiny》1986,101(2):163-165
The effect of antioxidant--alpha-tocopherol--on Ca2+-transporting system in sarcoplasmic reticulum (SR) of the rabbit skeletal muscles was studied in hypercholesterolemia (HC). alpha-tocopherol administration to animals with HC produced a break on the curve of temperature dependence of Ca-ATPase activity at about 20 degrees C, that disappeared in HC, increased the rate of "rapid" SH-group binding by thiol reagents, and normalized the level of unsaturated fatty acids in SR membranes without altering phospholipid content. It is suggested that the damage of Ca-ATPase in HC is mainly due to activation of lipid peroxidation. 相似文献
2.
mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species 总被引:4,自引:0,他引:4
Reconstructions of the human-African great ape phylogeny by using
mitochondrial DNA (mtDNA) have been subject to considerable debate. One
confounding factor may be the lack of data on intraspecific variation. To
test this hypothesis, we examined the effect of intraspecific mtDNA
diversity on the phylogenetic reconstruction of another Plio- Pleistocene
radiation of higher primates, the fascicularis group of macaque (Macaca)
monkey species. Fifteen endonucleases were used to identify 10 haplotypes
of 40-47 restriction sites in M. mulatta, which were compared with similar
data for the other members of this species group. Interpopulational,
intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of
divergence time and branching order incorporating this variation were
substantially different from those based on single representatives of each
species. We conclude that intraspecific mtDNA diversity is substantial in
at least some primate species. Consequently, without prior information on
the extent of genetic diversity within a particular species, intraspecific
variation must be assessed and accounted for when reconstructing primate
phylogenies. Further, we question the reliability of hominoid mtDNA
phylogenies, based as they are on one or a few representatives of each
species, in an already depauperate superfamily of primates.
相似文献
3.
The synthesis and degradation of rat brain synaptosomal proteins were studied in three groups of animals: trained the behaviour pattern in the maze, "pseudo-trained" and control. These processes were assessed from protein specific radioactivity after 1, 3 days and after 1, 3, 6 and 9 weeks following intraventricular injection of 14C-lysine. The experiments showed three fractions differing in overall values of half-life (T50). An increase in specific radioactivity of brain proteins of trained animals was revealed as compared to that in "pseudo-trained" and control rats. T50 was recorded to rise for slow-metabolizing fractions of synaptosomal proteins of trained rats. Participation of synaptosomal proteins in the mechanisms of long-term memory is discussed. 相似文献
4.
Isolation of calcium pump system and purification of calcium ion-dependent ATPase from heart muscle.
D O Levitsky M K Aliev A V Kuzmin T S Levchenko V N Smirnov E I Chazov 《Biochimica et biophysica acta》1976,443(3):468-484
The procedure for the isolation of the highly active fraction of sarcoplasmic reticulum from pigeon and dog hearts is described. The method is based on the partial loading of heart microsomes with calcium and oxalate ions and the precipitation of loaded vesicles in sucrose and potassium chloride concentration gradients. Preparations obtained possess high activity of Ca2+-dependent ATPase and are also able to accumulate up to 10 mumol Ca2+ per mg protein. Purification of sarcoplasmic reticulum membranes is accompanied by a decrease in concentration of cytochrome a+a3 and an increase in the content of [32P]phosphoenzyme. The basic components in "calcium-oxalate preparation" from hearts are proteins with molecular weights of about 100000 (Ca2+-dependent ATPase) and 55000 Calcium-oxalate preparation from pigeon hearts was used for subsequent purification of Ca2+-dependent ATPase. Specific activity of purified enzyme from pigeon hearts is 12-16 mumol Pi/min per mg protein. Enzyme activity of purified Ca2+-dependent ATPase is inhibited by EGTA and is not sensitive to azide, 2,4-dinitrophenol and ouabain. The data obtained demonstrate the similarity of calcium pump systems and Ca2+-dependent ATPases isolated from heart and skeletal muscles. 相似文献
5.
Roelfsema MR Levchenko V Hedrich R 《The Plant journal : for cell and molecular biology》2004,37(4):578-588
During drought, the plant hormone abscisic acid (ABA) induces rapid stomatal closure and in turn reduces transpiration. Stomatal closure is accompanied by large ion fluxes across the plasma membrane, carried by K+ and anion channels. We recorded changes in the activity of these channels induced by ABA, for guard cells of intact Vicia faba plants. Guard cells in their natural environment were impaled with double-barrelled electrodes, and ABA was applied via the leaf surface. In 45 out of 85 cells tested, ABA triggered a transient depolarization of the plasma membrane. In these cells, the membrane potential partially recovered in the presence of ABA; however, a full recovery of the membrane potentials was only observed after removal of ABA. Repetitive ABA responses could be evoked in single cells, but the magnitude of the response varied from one hormone application to the other. The transient depolarization correlated with the activation of anion channels, which peaked 5 min after introduction of the stimulus. In guard cells with a moderate increase in plasma membrane conductance (DeltaG < 5 nS), ABA predominantly activated voltage-independent (slow (S)-type) anion channels. During strong responses (DeltaG > 5 nS), however, ABA activated voltage-dependent (rapid (R)-type) in addition to S-type anion channels. We conclude that the combined activation of these two channel types leads to the transient depolarization of guard cells. The nature of this ABA response correlates with the transient extrusion of Cl- from guard cells and a rapid but confined reduction in stomatal aperture. 相似文献
6.
Briukhanov AF Levchenko BI Tikhenko NI Degtiareva LV Tsygankova RE Sysoliatina GV Leshchenko IV Tokhov IuM 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2003,(6):56-59
The data obtained in the analysis of the epidemiological situation in tularemia in the zone of inundation in the Stavropol Territory in 2002 are presented. The current systematic epidemiological surveillance, as well as the data of urgent epizootological and epidemiological survey in the zone of inundation permitted the objective prognostication of the situation in tularemia and formed the basis for the rational planning and realization of prophylactic measures. 相似文献
7.
Levchenko A 《Biotechnology and bioengineering》2003,84(7):773-782
Years of careful experimental analysis have revealed that signaling molecules are organized into complex networks of biochemical reactions exquisitely regulated in time and space to provide a cell with high-fidelity information about an extremely noisy and volatile environment. A new view of signaling networks as systems consisting of multiple complex elements interacting in a multifarious fashion is emerging, a view that conflicts with the single-gene or protein-centric approach common in biological research. The postgenomic era has brought about a different, network-centric methodology of analysis, suddenly forcing researchers toward the opposite extreme of complexity, where the networks being explored are, to a certain extent, intractable and uninterpretable. Both the cartoons of simple pathways and the very large "hair-ball" diagrams of large intracellular networks are also representations of static worlds, superficially devoid of dynamics and chemistry. These representations are often viewed as being analogous to stably linked computer and neural networks rather than dynamically changing networks of chemical interactions, where the notions of concentration, compartmentalization, and diffusion may be the primary determinants of connectivity. Arguably, the systems biology approach, relying on computational modeling coupled with various experimental techniques and methodologies, will be an essential component of analysis of the behavior of signal transduction pathways. Combining the dynamical view of rapidly evolving responses and the structural view arising from high-throughput analyses of the interacting species will be the best approach toward efforts toward greater understanding of intracellular signaling processes. 相似文献
8.
SspB dimers bind proteins bearing the ssrA-degradation tag and stimulate their degradation by the ClpXP protease. Here, E. coli SspB is shown to contain a dimeric substrate binding domain of 110-120 N-terminal residues, which binds ssrA-tagged substrates but does not stimulate their degradation. The C-terminal 40-50 residues of SspB are unstructured but are required for SspB to form substrate-delivery complexes with ClpXP. A synthetic peptide containing the 10 C-terminal residues of SspB binds ClpX, stimulates its ATPase activity, and prevents SspB-mediated delivery of GFP-ssrA for ClpXP degradation. This tripartite structure--an ssrA-tag binding and dimerization domain, a flexible linker, and a short peptide module that docks with ClpX--allows SspB to deliver tagged substrates to ClpXP without interfering with their denaturation or degradation. 相似文献
9.
Menshutkin VV Kazanskiĭ AB Levchenko VF 《Zhurnal evoliutsionno? biokhimii i fiziologii》2010,46(6):450-460
The history of rise and development of evolutionary methods in Saint Petersburg school of biological modelling is traced and analyzed. Some pioneering works in simulation of ecological and evolutionary processes, performed in St.-Petersburg school became an exemplary ones for many followers in Russia and abroad. The individual-based approach became the crucial point in the history of the school as an adequate instrument for construction of models of biological evolution. This approach is natural for simulation of the evolution of life-history parameters and adaptive processes in populations and communities. In some cases simulated evolutionary process was used for solving a reverse problem, i. e., for estimation of uncertain life-history parameters of population. Evolutionary computations is one more aspect of this approach application in great many fields. The problems and vistas of ecological and evolutionary modelling in general are discussed. 相似文献
10.