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91.
H. Kang G. Namkoong 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1980,58(3-4):181-191
Summary The influence of unbalanced mating systems — factorial mating (FM) and random loss of families after a full diallel crossing (RS) — on the ultimate probability of gene fixation (u()) and the time required to fix or lose a gene (t()) are investigated. The average u() of these systems is smaller than that of random mating, and the range of u() for a given initial parental genotype combination is very large (close to one for most initial genotypic combinations). The average u() of different parental genotypic combinations of a given gene frequency are different. These systems accelerate the t().This article was written and prepared by U.S. Government employees on official time, and it is therefore in the public domain 相似文献
92.
A suspension ofPlasmodium berghei obtained by lysis with saponin of red blood cells from an infected rat showed high hemolytic activity, when incubatedin vitro with normal rat red blood cells. The hemolysis was a temperature-dependent process and was dependent on the concentration
of the parasite. Plasma ofPlasmodium berghei infected albino rats also possessed lytic activity. 相似文献
93.
94.
95.
Luminol chemiluminescence was used to detect activation of the respiratory burst oxidase in bovine eosinophils and neutrophils. Extracellular and intracellular chemiluminescence were measured by supplementing the medium with horseradish peroxidase and catalase, respectively. Pure bovine eosinophils (> 90%), maximally stimulated with 1 nmol/l phorbol 12-myristate-13-acetate (PMA) showed ten times more extracellular luminol-dependent chemiluminescence (CL) than maximally stimulated pure bovine neutrophils (> 96%). Extracellular CL from eosinophils was preferably induced over intracellular CL by both PMA (27-fold difference) and platelet-activating factor (PAF) at 2 μmol/l (9-fold difference), but not by calcium ionophore A23187 (15 μmol/l). Time course information was used in the following experiments to distinguish between the mode of action of various stimulants. A progressively longer lag period was observed in eosinophil suspensions treated with decreasing doses of PMA, whereas platelet-activating factor induced a dose-dependent increase in the maximum response with no change in time to peak CL. The time course of extracellular CL was almost identical to intracellular CL for all stimulants tested, providing no evidence to suggest that extracellular CL stems from a different enzyme system than intracellular CL. Eosinophils generated most extracellular CL when stimulated with PMA, whereas neutrophils were most efficiently stimulated with A23187, which induced intracellular CL in eosinophils as well as in neutrophils. This accords with the greater tendency of neutrophils to ingest and kill microorganisms, whereas eosinophils are armed to destroy large extracellular targets. 相似文献
96.
Previous studies from this laboratory have shown that the phosphorylation of the S6 protein of the ribosomes is catalyzed by at least two different and separable kinase activities in PC12 cells. One of these activities is increased by treatment of the cells with nerve growth factor, the other by treatment of the cells with epidermal growth factor. The present work shows that these two factors stimulate the phosphorylation of S6 with quite different kinetics, and that both the number of phosphates incorporated into S6 and the phosphopeptide pattern of S6 are different in cells treated with nerve growth factor than in cells treated with epidermal growth factor. The characteristics of the nerve growth factor-sensitive S6 kinase and of the epidermal growth factor-sensitive kinase were also clearly different. Substrate specificity and inhibitor studies indicated that neither was identical to cyclic AMP-dependent kinase, kinase C, or the calcium/calmodulin-dependent kinases. However, two major phosphopeptides produced by S6 phosphorylation in nerve growth factor-treated cells were also seen on phosphorylation of S6 by cyclic AMP-dependent kinase in vitro. In addition, when rat liver 40S ribosomal subunits were pretreated with cyclic AMP-dependent kinase in vitro, the action of the nerve growth factor-sensitive S6 kinase was increased about twofold. 相似文献
97.
X-ray absorption fine structure experiments were performed to study structural and dynamic aspects of the active site of various forms of myoglobin. The structures determined for deoxyMb, MbCO, and MbO2 are consistent with the structure established by X-ray absorption fine structure experiment and X-ray crystallography. The first shell of ferrous MbNO determined contains 5 nitrogens located at 2.02 A and a short NO bond length of 1.76 A. This study focuses on the change of the XAFS Debye-Waller factor with temperature, which is a measure of thermal and static disorder. It was found that the changes of Debye-Waller factor with temperature for the Mb proteins, except deoxyMb, are consistent with a simple Einstein model, in which a single frequency was assumed for the bond stretching modes. In contrast, the temperature dependence of deoxyMb cannot be fitted to the Einstein model and a large disorder was found at low temperatures, which indicates the existence of conformational substates of the active site. 相似文献
98.
A circular dichroism-based detection system presents several advantages in the HPLC analysis of chiral compounds because of the selective monitoring of optically active molecules. Its use allows reliable determination of enantiomeric excesses and elution order. To this end, the application of empirical, semiempirical, and nonempirical methods to get stereochemical information from the CD signal is reported. Furthermore, recording the CD spectra on line and evaluation of the dissymetry factor make the CD detection very powerful in characterizing the stereochemistry of chiral eluates. 相似文献
99.
Summary A metamorphosis-inducing factor was isolated from medium conditioned by either metamorphosing larvae or 3-day postmetamorphic primary polyps. The factor has a molecular weight 8 kDa and is heatlabile. It does not induce metamorphosis of isolated posterior fragments and is therefore not identical to the internal signal described by Schwoerer-Böhning et al. (1990). The biological significance of the substance is currently unclear, therefore its inducing activity may be a side effect. 相似文献
100.
Takashi Ariizumi Naomi Moriya Hideho Uchiyama Makoto Asashima 《Development genes and evolution》1991,200(4):230-233
Summary Human recombinant activin A, which is identical with erythroid differentiation factor (EDF), was tested for its mesoderm-inducing activity in concentrations from 0.3–50 ng/ml, using ectoderm of Xenopus late blastula (Stage 9) as the responding tissue. At a low concentration of activin A, blood-like cells, mesenchyme, and coelomic epithelium were induced; at a moderate concentration muscle and neural tissue, and at a high concentration notochord. Activin A thus induced all mesodermal tissues in a dose-dependent manner, such that a low dose induced ventral structures and a high dose induced dorsal structures. Activin may act as an intrinsic inducing molecule responsible for establishing the dorso-ventral axis in early Xenopus development.
Offprint requests to: M. Asashima 相似文献