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31.
Studies on the nature of replicating DNA of HeLa cells 总被引:5,自引:0,他引:5
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Marion Barclay R. K. Barclay V. P. Skipski Olga Terebus-Kekish C. H. Mueller Ellen Shah W. L. Elkins 《The Biochemical journal》1965,96(1):205-209
1. Lipoproteins were measured in sera from 11 young women having a similar environment and diet. Sera were obtained at weekly intervals over a 12-week period. The values of the lipoproteins during periods in the normal ovulatory cycle were compared to assess their relation to reported hormone concentrations in blood. 2. Only the 4–0sf (HDL2) (d 1·125 sodium chloride) fraction changed significantly; it increased at ovulation in ten of the 11 subjects and fell as menstruation approached. 3. There was greater variability in most of the low-density rather than the high-density lipoproteins within individuals. The lipoprotein class most characteristic for an individual was the 4–0sf or HDL2 fraction. 相似文献
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Three states for the formyl peptide receptor on intact cells 总被引:2,自引:0,他引:2
Three distinct states of the formyl peptide receptor have been described. These are: 1) the ternary complex of ligand, receptor, and G protein (LRG); 2) the rapidly dissociating occupied receptor (ligand-receptor complex (LR]; and 3) a desensitized slowly dissociating guanine nucleotide-insensitive receptor (desensitized ligand-receptor complex ("LRX"]. During cell activation there is a rapid interconversion among receptor states from a rapidly dissociating form (t 1/2 approximately 10 s) to a slowly dissociating form (t 1/2 greater than or equal to 2 min). Neither the dynamics of the states nor their interconversion is influenced by ribosylation of G protein in the presence of pertussis toxin. In contrast to ribosylation, treatment of cells with either 2-deoxyglucose or fluoride ion, both of which lead to a loss of adenine and guanine nucleotides, causes a time-dependent change in ligand dissociability. After short periods of treatment (5-15 min) rapid dissociation is observed; after longer times (30-60 min), slow dissociation is once again detected. When intact cells are first ribosylated and then energy-depleted, only a rapidly dissociating receptor is detected. These results are discussed in terms of a model with the following elements: 1) intact cell dynamics during cell activation are dominated by an energy-dependent interconversion from LR to LRX; 2) under activation conditions, LRG appears and disappears too rapidly to be detected; 3) in cells depleted of energy and guanine nucleotide, LRG is stabilized; 4) in cells both ribosylated and depleted of energy, LR is stabilized. 相似文献
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Sensory interaction and sensory adaptation in short- and long-lasting space flights (SF) and the dynamics of stability of adaptive shifts were studied by the phenomenology of spontaneous and visually induced illusory reactions. It was shown that perceptive impairment developed during the initial adaptation to microgravity should be considered regular reactions of sensory systems under given environmental conditions rather than special features of the individuals examined. The classification of spontaneous illusory reactions (SIR) under conditions of microgravity and the results of investigation of the vertical vection (vection is a visual illusion evoked by the optokinetic stimulation) are presented. The following previously unknown phenomena were registered for the first time: inversion of the vertical vection illusion (VVI) evoked by vertical and sinusoidal optokinetic stimulation, impairment of perception of the body schema during VVI, change in the character of VVI, and development of VVI asymmetry. During long-lasting existence under conditions of weightlessness the anomalous perceptive reactions continued to be registered episodically (the period of adaptation was replaced by that of deadaptation). A hypothesis was suggested for the possible mechanisms of the phenomena found. [Translated from Fiziologiya Cheloveka, vol. 21, no. 4, p. 50-62, July-August, 1995] 相似文献
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Dis3, implicated in mitotic control, binds directly to Ran and enhances the GEF activity of RCC1. 总被引:9,自引:0,他引:9 下载免费PDF全文
E Noguchi N Hayashi Y Azuma T Seki M Nakamura N Nakashima M Yanagida X He U Mueller S Sazer T Nishimoto 《The EMBO journal》1996,15(20):5595-5605
Using the two-hybrid method, we isolated a Saccharomyces cerevisiae cDNA encoding a protein homologous to Schizosaccharomyces pombe protein Dis3sp, using as bait, human GTPase Ran. The DIS3 gene is essential for viability and complements S.pombe mutant dis3-54 which is defective in mitosis. Although Dis3sc has no homology to RanBP1, it bound directly to Ran and the S.cerevisiae Ran homologue Cnr1, but not to the S.cerevisiae RCC1 homologue Srm1. Upon binding to Ran with a 1:1 molar ratio, Dis3sc enhanced a nucleotide-releasing activity of RCC1 on Ran. In the presence of Dis3sc, the K(m) of RCC1 on Ran decreased by half, while the kcat was unchanged. In vivo, Dis3sp was present as oligomers of M(r) 670-200 kDa as previously reported, and the 200 kDa oligomer of Dis3sp was found to include Spi1 and Pim1, the S.pombe homologues of Ran and RCC1, respectively. Although the biological function of the heterotrimeric oligomer consisting of Dis3, Spi1 and Pim1 is unknown, our results indicate that Dis3 is a component of the RCC1-Ran pathway. 相似文献
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The rate of decay of genetic variation is determined for randomly mating autotetraploid populations of finite size, and the equilibrium homozygosity under mutation and random drift is calculated. It is shown that heterozygosity is lost at a slower rate than in diploid populations, and that the equilibrium heterozygosity with mutation and random drift is higher than for diploids. Outcrossing populations as well as populations that randomly self are analyzed. A method of comparing genetic variation between autotetraploid and diploid populations is proposed. Our treatment suggests that the ``gametic homozygosity' provides a unified approach for comparing genotypes within a population as well as comparing genetic variation between populations with different levels of ploidy. 相似文献
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J. Torabinejad R. J. Mueller 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,86(2-3):288-294
Summary Four hybrids were obtained between three Australian Elymus taxa and three cereal grains: wheat, rye, and barley. Mean meiotic metaphase-I configurations were 41.14 I, 0.42 rod II, 0.003 ring II, and 0.01 III for E. scabrus var plurinervis x Triticum aestivum (1 hybrid plant), 22.27 I, 2.63 rod II, 0.06 ring II, and 0.12 III for E. scabrus var scabrus x Secale cereale (4 hybrid plants), and 26.65 I, 0.66 rod II, 0.00 ring II, and 0.01 III for E. scabrus var plurinervis x Hordeum vulgare (13 hybrid plants). The I genome of barley also paired very little in a BIII hybrid of apomictic E. rectisetus x H. vulgare (2 hybrid plants). Megasporogenesis in this BIII hybrid was at least facultatively apomeiotic, with the same sort of nuclear elongation, apomeiotic division, and dyad formation seen previously in E. rectisetus itself. All four hybrid combinations were sterile. While spike morphology in the E. scabrus x T. aestivum and E. scabrus x H. vulgare hybrids were intermediate to their parents, E. scabrus x S. cereale and E. rectisetus x H. vulgare looked like their maternal parents. 相似文献