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21.
T Takabatake M Hasegawa T Nagano M Hirobe 《The Journal of biological chemistry》1992,267(7):4613-4618
The O2-. production by aerobically cultured Escherichia coli in the presence of benzofurazan (1), 4,7-dimethylbenzofurazan (2), 4,7-dibromobenzofurazan (3), 4-bromo-6-cyanobenzofurazan (4), and 4,7-dicyanobenzofurazan (5) was examined by using the cytochrome c reduction method in order to elucidate the mechanism of cytotoxicity of benzofurazans. Adding compound 5 to E. coli cell suspension caused cytochrome c reduction, which was completely inhibited by superoxide dismutase. The rate of cytochrome c reduction was in the order of 1 = 2 = 3 less than 4 less than 5, which correlates well with that of the reduction potentials of these benzofurazans. Adding glucose to the E. coli cell suspension-compound 5-cytochrome c system accelerated the rate of cytochrome c reduction. The formation of 4,7-dicyanobenzofurazan anion radical in the cell suspension-compound 5-glucose system in the absence of O2 was followed by ESR spectroscopy. The ESR signal of the anion radical disappeared when O2 was added. Compound 5 was shown to have an approximately 10-fold greater increasing effect on the flux of O2-. by E. coli than paraquat (PQ) by the cytochrome c reduction method. The results were confirmed by the electrochemical method with an oxygen electrode. However, compound 5 had a bacteriostatic, but not lethal, effect, while PQ had both effects. The effect of compound 5 and PQ on lethality of E. coli showed a dramatic difference when E. coli was exposed to these two compounds and washed prior to testing the effects of that exposure. This difference probably arose because compound 5 readily leaked from the cells during dilution and plating. Also, the reduced form of compound 5 exits from the cells more readily than the reduced form of PQ and then generates O2-. in the medium by autoxidation. This suggests the importance of the intracellular production of O2-., rather than the extracellular production of O2-., for lethal effect. 相似文献
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N Iwai Y Yamano S Chaki F Konishi S Bardhan C Tibbetts K Sasaki M Hasegawa Y Matsuda T Inagami 《Biochemical and biophysical research communications》1991,177(1):299-304
The nucleotide and amino acid sequences for rat type I angiotensin II receptor were deduced through molecular cloning and sequence analysis of its complementary DNAs. The rat angiotensin II receptor consists of 359 amino acid residues and has a sequence similar to G protein-coupled receptors. The expression of this receptor gene was detected in the adrenal, liver and kidney by Northern blotting. Sodium deprivation positively modulated the expression of the receptor gene in the adrenal. No detectable change was observed in the expression levels of this receptor gene between spontaneously hypertensive rats and Wistar-Kyoto rats in the tissues examined including the adrenal, brain, kidney and liver. Interestingly the expression of this receptor gene was developmentally regulated. 相似文献
25.
Cell-division inhibitor produced by a killer strain of cellular slime mold Polysphondylium pallidum 总被引:1,自引:1,他引:0
The killer strain CK-8 of cellular slime mold Polysphondylium pallidum produces a cell-division inhibitor, in addition to a killer factor. This inhibitor represses cell division of many strains and species of cellular slime molds, except CK-8 itself and its complementary mating-type strain. It is sensitive to both heat and trypsin, and capable of binding to Con A. Its apparent molecular mass is more than 100 kDa. Repression of cell division by this inhibitor is reversed by trypsin treatment of the cells. 相似文献
26.
Anti-platelet aggregating and disaggregating activities of the chemically stable 6,9-methano prostaglandin I2 (6,9-methano PGI2) were investigated. 6,9-Methano PGI2 inhibited ADP-induced platelet aggregation in PRP from humans, rabbits and rats. 6,9-Methano PGI2 also inhibited rabbit platelet aggregation induced by ADP, collagen, thrombin, arachidonic acid and 11,9-epoxy-methano PGH2. Antiaggregating activities of 6,9-methano PGI2 were 0.3 to 2.0 times greater than those of PGE1. 6,9-Methano PGI2 facilitated platelet disaggregation in a dose related manner. Antiaggregating and disaggregating activities of 6,9-methano PGI2 were markedly enhanced by incubation with the phosphodiesterase inhibitor, theophylline. 相似文献
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An improved culture medium for mouse blastocysts 总被引:7,自引:0,他引:7
Akiko Spindle 《In vitro cellular & developmental biology. Plant》1980,16(8):669-674
Summary Eagle's basal medium, modified to contain essential amino acids at the concentrations optimal for mouse blastocyst hatching,
attachment, and outgrowth, supported in vitro development of the mouse blastocyst better than other tissue culture media tested.
This medium was improved for growth and differentiation of the inner cell mass by doubling the concentration of amino acids
and glucose and by adding uridine (10−5
M) and β-mercaptoethanol (10−5
M). In this improved medium nearly all blastocysts grown from the two-cell stage hatched and formed trophoblast outgrowths,
and 62% developed into two-layer egg cylinders.
This work was supported by the U.S. Department of Energy. 相似文献
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The preferential codon usages in variable and constant regions of immunoglobulin genes are quite distinct from each other. 总被引:7,自引:3,他引:4 下载免费PDF全文
The pattern of codon utilization in the variable and constant regions of immunoglobulin genes are compared. It is shown that, in these regions, codon utilizations are quite distinct from one another: For most degenerate codons, there is a selective bias that prefers C and/or G ending codons to U and/or A ending codons in the constant region compared with the bias in the variable region. This would strongly suggest that, in immunoglobulin genes, the bias in code word usage is determined by other factors than those concerning with the translational mechanism such as tRNA availability and codon-anticodon interaction. A possibility is also suggested that this differance of code word usage between them is due to the existence of secondary structure in the constant region but not in the variable region. 相似文献