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61.
62.
Flow cytometry analysis of DNA degradation in thymocytes of gamma-irradiated or hydrocortisone treated rats 总被引:1,自引:0,他引:1
V A Pechatnikov V N Afanasyev B A Korol V N Korneev S R Rochev YuAUmansky 《General physiology and biophysics》1986,5(3):273-284
The pattern of DNA degradation in thymocytes of irradiated or hydrocortisone-treated rats has been studied by means of flow cytometry of the cells, treated with probes specifically bound to the AT or GC-pairs of DNA. It has been shown that the death of thymocytes is accompanied by a decrease in their DNA content. The main features of the occurrence and accumulation of cells with a DNA content less than the normal diploid level correspond with those of internucleosomal DNA fragmentation: such cells appear after a 1 hour lag-period, their accumulation is prevented by cycloheximide injection and is lower at 300 Gy than at doses of 10 to 30 Gy. At the same time, no increase in permeability of the cell membrane to ethidium bromide was observed up to the sixth hour after irradiation. Most of the thymocytes dying under the action of irradiation or hydrocortisone are in the G0 or G1 phases of the cell cycle. The method used allows detection of the cells with cleaved but not removed DNA. 相似文献
63.
A M Ugolev B Z Zaripov N N Iezuitova A A Gruzdkov I S Rybin M I Voloshenovich A A Nikitina N T Punin MYuTokgaev 《Comparative biochemistry and physiology. A, Comparative physiology》1986,85(4):593-612
Literature data and the results of our investigations using both generally accepted and original perfusion techniques of the isolated loop of the rat small intestine in in vivo experiments are reviewed. Significant differences in the functioning of the small intestine under conditions of acute and chronic experiments are revealed. It has been established that in chronic experiments as compared to acute ones: (a) the absorption of glucose, galactose, fructose and glycine is 2-5 times higher; (b) Kt as well as Jmax values of the transport of these nutrients differ considerably; (c) Na+-independent mechanism of glucose and glycine transport predominates; (d) higher rates of membrane hydrolysis and more effective interactions between enzyme and transport systems of the enterocyte brush border membranes are observed; (e) functional characteristics of the small intestine affected by various experimental factors are more stable. The conclusion is made that it is necessary to revise current views of the scale and regularities of digestive-transport processes in the small intestine under physiological conditions. The importance of the suggested approaches for general and comparative physiology and biochemistry is discussed. 相似文献
64.
Utilization of energy stored in the form of Na+ and K+ ion gradients by bacterial cells 总被引:7,自引:0,他引:7
I I Brown A N Galperin MYuGlagolev V P Skulachev 《European journal of biochemistry》1983,134(2):345-349
The hypothesis that Na+ and K+ gradients have an energy storing function [V. P. Skulachev (1978) FEBS Lett. 87, 171-176] has been tested in experiments with Escherichia coli, the marine bacterium Vibrio harveyi, an extremely halophilic Halobacterium halobium and a fresh-water cyanobacterium Phormidium uncinatum from Lake Baikal living at an extremely low salt concentration. The capability of these microorganisms to maintain delta microH was compared using motility as a delta microH-supported function. It was found that in all cases the gradient of monovalent cations is competent to prolong the period of active motility after other energy sources are exhausted. Maximal prolongation was found in H. halobium, which in a Na+ medium was still motile when light was switched off for 9 h under anaerobic conditions. In V. harveyi the motility was maintained for 1 h, in E. coli for about 10 min and in Ph. uncinatum for about 2 min. Thus the delta microH buffer capacity of the monovalent cation gradient is proportional to the content of these cations in the habitat. It was also found that in Ph. uncinatum only delta pK is effective, whereas in E. coli and V. harveyi both delta pK and delta pNa are. In E. coli when the K+ release is completed and the cells become motionless, motility can be temporarily restored by adding NaCl which initiates an H+ efflux. Under conditions of exhaustion of energy sources, the Na+ and K+ gradient was shown to stabilize potential in H. halobium cells, measured with a tetraphenylphosphonium probe. In H. halobium and E. coli, the anaerobic ATP level was found to stabilize when the Na+ and K+ gradients were present. Addition of N,N'-dicyclohexylcarbodiimide destabilized this level, which indicated that Na+ and K+ gradients could support de novo ATP synthesis. It is concluded that the data obtained are in agreement with the concept of the energy storing by the Na+ and K+ gradients. Other functions of these gradients and the mechanisms of their formation are discussed. 相似文献
65.
Y Wada A Hayashi F Masanori I Katakuse T Ichihara H Nakabushi T Matsuo T Sakurai H Matsuda 《Biochimica et biophysica acta》1983,749(3):244-248
Molecular secondary ion mass spectrometry has characterized the structure of a new fetal hemoglobin variant, Hb F Izumi, without separation of peptides or amino acid analysis. First, the mass spectrum of a tryptic digest of the abnormal gamma globin revealed a decreased by 72 mass units in the molecular mass of peptide T-1,2, indicating the presence of a Glu leads to Gly substitution. Next, the analysis of the digest produced by the addition of staphylococcal protease, which specifically cleaves glutamyl peptide bonds, determined the site of substitution at 6th glutamic acid residue in peptide T-1,2 which contains two glutamic acid residues. Since this mass spectrometric approach provides digitalized data on peptide analysis, we call it 'digit printing'. The high sensitivity of this technique is especially promising for the analysis of molecular abnormality in various genetic disorders. 相似文献
66.
Inhibition of neuronal sodium and potassium ion activated adenosinetriphosphatase by pyrithiamin 总被引:1,自引:0,他引:1
Since one of the electrophysiological effects of pyrithiamin, an antimetabolite of thiamin, suggested an interference with sodium pump mechanisms, the effect of pyrithiamin on Na+,K+-ATPase was investigated. We found that whereas preincubation of the antimetabolite with nonneuronal preparations of Na+,K+-ATPase produced only minimal inhibition, the enzyme derived from brain preparations was markedly inhibited. This inhibition could be prevented by thiamin but not reversed. The kinetic study showed that pyrithiamin acts in a noncompetitive manner with respect to the activation of the enzyme by ATP, Na+, and K+. Pyrithiamin inhibited Na+-dependent phosphorylation and K+-stimulated phosphatase as well as ouabain binding, and these inhibitions were parallel with that of the overall Na+,K+-ATPase reaction. In addition, the antimetabolite caused a significant change in the turbidity of the enzyme suspension. The results suggest that pyrithiamin may induce a structural change of the enzyme complex. 相似文献
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70.
System for the Investigation of the Bacteriophage-directed Synthesis of Diphtherial Toxin 总被引:11,自引:1,他引:10 下载免费PDF全文
Lytic corynebacteriophage betahv64(tox+) has been characterized, and methods for studying the expression of its tox(+) gene in nontoxinogenic Corynebacterium diphtheriae strain C7(s)(-)(tox-) described. During one cycle of viral growth there was a 1 million-fold increase in extracellular toxin. Both the conditions of the experiment and the use of purified phage, free from toxin, support the conclusion that all of the toxin was newly formed. This toxin was immunochemically indistinguishable from standard toxin produced by the PW8(r)(Pdi)(tox+) strain. Chloramphenicol was found to be an effective agent for synchronizing the initiation of viral growth. Once chloramphenicol was removed, intracellular toxin appeared and continued to increase throughout the latent period. Proflavine, added early in the latent period, blocked phage maturation without similarly affecting yields of toxin. Iron exerted a limited inhibitory effect on final toxin levels attained. 相似文献