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991.
992.
Rab GTPases require special machinery for protein prenylation, which include Rab escort protein (REP) and Rab geranylgeranyl transferase (RGGT). The current model of Rab geranylgeranylation proposes that REP binds Rab and presents it to RGGT. After geranylgeranylation of Rab C-terminal cysteines, REP delivers the prenylated protein to membranes. The REP-like protein Rab GDP dissociation inhibitor (RabGDI) then recycles the prenylated Rab between the membrane and the cytosol. The recent solution of crystal structures of the Rab prenylation machinery has helped to refine this model and provided further insights. The hydrophobic prenyl binding pocket of RGGT and geranylgeranyl transferase type-I (GGT-I) differs from that of farnesyl transferase (FT). A bulky tryptophan residue in FT restricts the size of the pocket, whereas in RGGT and GGT-I, this position is occupied by smaller residues. A highly conserved phenylalanine in REP, which is absent in RabGDI, is critical for the formation of the REP:RGGT complex. Finally, a geranylgeranyl binding site conserved in REP and RabGDI has been identified within helical domain II. The postprenylation events, including the specific targeting of Rabs to target membranes and the requirement for single versus double geranylgeranylation by different Rabs, remain obscure and should be the subject of future studies. 相似文献
993.
V L Bianky L Z Ka?danov S N Novikov 《Zhurnal vysshe? nervno? deiatelnosti imeni I P Pavlova》1979,29(6):1239-1247
An attempt was made to obtain with the help of selection-genetic method, mice lines with genetically determined differences in lateralization of the fore-legs (right-, left-handedness). In 5 generations of selection, 302 animals-offsprings were studied, obtained through crossing of the lines CBA X C57BL/6. Two parameters of asymmetry were investigated: direction and degree. It is shown that the genotype controls the degree of the lateralization of the fore-legs, whereas the direction of lateralization is not subjected to a rigid genetic control. In the studied mice population, "right-handed" mice prevail over "left-handed" ones, which seems to be due to their dwelling conditions in the early ontogenesis. 相似文献
994.
The occurrence of foeveola palatina was studied in 264 patients. The distance of the foveola palatina from the papilla incisiva and palatinal raphe was measured. Light and electron microscopic examinations were carried out on specimens obtained from cadavers. It was found that ducts of functioning mucous glands open into the foveolar lumen lined by stratified epithelium. 相似文献
995.
Recurrence plots of neuronal spike trains 总被引:2,自引:0,他引:2
The recently developed qualitative method of diagnosis of dynamical systems — recurrence plots has been applied to the analysis of dynamics of neuronal spike trains recorded from cerebellum and red nucleus of anesthetized cats. Recurrence plots revealed robust and common changes in the similarity structure of interspike interval sequences as well as significant deviations from randomness in serial ordering of intervals. Recurring episodes of alike, quasi-deterministic firing patterns suggest the spontaneous modulation of the dynamical complexity of the trajectories of observed neurons. These modulations are associated with changing dynamical properties of a neuronal spike-train-generating system. Their existence is compatible with the information processing paradigm of attractor neural networks. 相似文献
996.
Low molecular weight peptidic component extracted from maturing male sex organs of Chara tomentosa, capable of inducing increased condensation of chromosomes and profound changes in the cell cycle progression, was applied
to gametophytes of Anemia phyllitidis. Morphogenetic effects were studied with regard to cell divisions and GA3-induced antheridiogenesis. As compared with both the GA
3
−
and GA
3
+
control samples, the extract-treated prothallia exhibited considerably lowered number of cells and altered morphology. Antheridial
differentiation in prothallia of A. phyllitidis was severely inhibited when peptidic extract was added to medium containing GA3. Considering endocytotic uptake, evidenced in root meristems, and those effects which have been observed in plant and human
cells, the activity of extracts obtained from male sex organs of Chara may be interpreted as inhibitory influence acting via repression or modification of the genetic device of the cells rather, than a direct consequence of the retardation of cell
division cycles. 相似文献
997.
A latex test was elaborated which served for evaluation of quality of rabbit immune sera for antigen 0 of selected Gram-negative bacteria. Sensitivity and specificity of this test in comparison with passive hemagglutination and immunoenzymatic DOT-ELISA reactions was evaluated. These studies were performed on immune sera for antigen O of Salmonella groups B, C1, C2, D and E, Yersinia pseudotuberculosis and in antigen preparations for above listed microorganisms both in homologous and heterologous systems. It was found that sensitivity of the latex test is 9 to 160 times lower than that of passive hemagglutination and 7 to 307 lower than for DOT-ELISA. Sensitivity of the latex test and passive hemagglutination reaction was evaluated on the basis of results of cross reaction between studied antigens and unabsorbed rabbit sera, establishing so called sensitivity indexes, which were informing how many times heterologous titer is lower than homologous titer. So evaluated sensitivity of the latex test was close to sensitivity of the passive hemagglutination reaction. It was found that slide latex test is characterized by satisfactory sensitivity and good sensitiveness and may be used for evaluation of antibody level 0 antigens of Salmonella and Yersinia. The value of this test is characterized by high repeatability of results, as well as low work and time-consuming. 相似文献
998.
Two HSV-1 strains were used in the study: McIntyre laboratory strain and "eye" strain isolated from a patient. Temperature-sensitive clone of HSV-1 was isolated from McIntyre strain as a consequence of virus replication carried out at lowered temperature (28 degrees C). Temperature-resistant clones were obtained from both strains through passages at 39 degrees C and through heating for four times at 45 degrees C. Pathogenic properties of the temperature clones obtained were determined in inbred mice Balb/c and CFw/Pzh. A loss of pathogenicity for mice of temperature-sensitive clone and an increase of pathogenicity of temperature-resistant clones were noted as compared to parental strains. It was found that an introduction of temperature-sensitive clone, with lowered virulence immunizes against highly virulent temperature-resistant clone. 相似文献
999.
There are "slow" and "rapid" acetylator phenotypes in mice according to N-acetyltransferase activity (E.C. 2.3.1.5) (N-AT). The results of direct, back- and reciprocal crosses of mice lines with rapid acetylation phenotype (C57BL/He) show monogenic autosomic control of acetylation locus (Ac) with rapid allele dominance and sex dependence upon N-AT activity in males. So, genetic polymorphism according to the Ac locus exists in mice as well as in some other animal species and in humans. The results obtained in this study demonstrated the correlation between the N-AT level in mice and their predisposition to malignant tumors as well as dependence of cyclophosphamide action on the N-AT activity upon the genotype of an individual, which suggests a certain role of the Ac locus in tumor development. 相似文献
1000.