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91.
M Takigawa Y Nishida F Suzuki J Kishi K Yamashita T Hayakawa 《Biochemical and biophysical research communications》1990,171(3):1264-1271
Treatment of yolk-sac membranes of 4-day-old chick embryos with spermine or spermidine resulted in angiogenesis in the membranes. The angiogenic activity of spermine was stronger than that of spermidine. Putrescine, polylysine and histamine did not induce angiogenesis in the membranes. Administration of putrescine, spermidine and spermine increased their respective levels in yolk-sac membranes, but no interconversion of these amines was observed. The increases in spermidine and spermine levels in yolk-sac membranes preceded induction of angiogenesis. The angiogenesis induced by spermine was inhibited by tissue inhibitors of metalloproteinases, that is, TIMP and TIMP-2. These findings suggest that spermine and spermidine are angiogenesis factors in yolk-sac membranes of chick embryos and that matrix metalloproteinases represented by collagenase are involved in their action. 相似文献
92.
Recovery of uranium by immobilized microorganisms 总被引:2,自引:0,他引:2
Akira Nakajima Takao Horikoshi Takashi Sakaguchi 《Applied microbiology and biotechnology》1982,16(2-3):88-91
Summary Some attempts were made to recover uranium from sea and fresh water using immobilized Streptomyces viridochromogenes and Chlorella regularis cells. The cells immobilized in polyacrylamide gel have the most favorable features for uranium recovery; high adsorption ability, good mechanical properties, and applicability in a column system. The adsorption of uranium by the immobilized cells is not affected by the pH values between 4 and 9. These results show that uranium adsorption becomes independent of pH after immobilization. The amounts of uranium adsorbed by the immobilized cells increased linearly with temperature, suggesting that the adsorption of uranium by the immobilized cells is an endothermic reaction. The immobilized cells can recover uranium almost quantitatively from both fresh and sea water containing uranium, and almost all uranium adsorbed is desorbed with a solution of Na2CO3. Thus the immobilized cells of Streptomyces and Chlorella can be used repeatedly in adsorption-desorption process.Studies on the Accumulation of Heavy Metal Elements in Biological Systems. XXI 相似文献
93.
Takao Shimizu Kigen Kondo Osamu Hayaishi 《Archives of biochemistry and biophysics》1981,206(2):271-276
In the presence of heme and reduced glutathione, prostaglandin (PG) endoperoxides underwent rapid conversion to malondialdehyde and 12l-hydroxy-5,8,10-heptadecatrienoic acid. In addition, PG endoperoxides as well as lipid peroxides produced malondialdehyde to yield a red pigment during the thiobarbituric acid reaction with different efficiencies. The relative rates of the reaction were: 1,1,3,3-tetraethoxypropane, 100; PGG2, 55; PGH2, 32; and 15-hydroperoxyarachidonic acid, 6. The thiobarbituric acid reactive materials in rabbit serum decreased by 25–60%, after intravenous administration of aspirin (a cyclo-oxygenase inhibitor) and with a concomitant decline of serum PG levels. These results, taken together, suggested that serum thiobarbituric acid values, considered to be an indicator of lipid peroxide levels, were to a significant extent due to PG endoperoxides and their derivatives. 相似文献
94.
Hiroshi Hayakawa Kanji Ishizaki Masao Inoue Takashi Yagi Mutsuo Sekiguchi Hiraku Takebe 《Mutation research》1981,80(2)
DNA-repair characteristics of xeroderma pigmentosum belonging to complementation group F were investigated. The cells exhibited an intermediate level of repair as measured in terms of (1) disappearance of T4 endonuclease-V-susceptible sites from DNA, (2) formation of ultraviolet-induced strand breaks in DNA, and (3) ultraviolet-induced unscheduled DNA synthesis during post-irradiation incubation. The impaired ability of XP3YO to perform unscheduled DNA synthesis was restored, to half the normal level, by the concomitant treatment with T4 endonuclease V and ultraviolet-inactivated Sendai virus. It is suggested that xeroderma pigmentosum cells of group F may be defective, at least in part, in the incision step of excision repair. 相似文献
95.
Electrotonic Coupling between Adjacent Internodal Cells of Chara braunii: Transmission of Action Potentials beyond the Node 总被引:1,自引:0,他引:1
Many nodal cells are interposed between two internodal cellsof Chara braunii. When an action potential conducted in an internodereached the node, no electrical activation in the nodal cellscould be found, although an area of the membrane bordering thenodal cells in this internode was partially activated (end-membraneaction potential). When the action potential approached thenode along the stimulated internode, an electrotonic potentialchange (depolarization) was produced in the other internode.This depolarization was greatly depressed by the end-membraneaction potential of the stimulated internode, so that hardlyany transmission took place. The ratio of the potential changein the surface membrane of the adjoining ("postsynaptic") internode(cell b) to that of the stimulated one (cell a), the couplingratio, eb/ea, can be estimated from a simple equivalent circuitof the nodal region composed of two surface-membrane resistances(Ra, Rb) and intercellular resistance (Rn). If Rn remains thesame, a higher ratio should be produced with a larger Rb, butthe ratio does not depend on any change in Ra, which could beproved experimentally. Transmission of the action potentialbeyond the node was frequent when the coupling ratio was increasedand when the threshold that elicits the action potential waslowered by immersing the node in a K or Na salt solution.
1 Present address: Department of Physiology, Tohoku UniversitySchool of Dentistry, Sendai 980, Japan. (Received December 1, 1980; Accepted January 23, 1981) 相似文献
96.
Potassium uptake rhythm in the long-day duckweed Lemna gibbaG3 grown at 26?C disappeared at temperatures below 12?C. However,when the plants were returned to 26?C, the rhythm immediatelyrestarted from circadian time 12 with its normal wave form.Temperature steps from 20 to 30?C or from 30 to 20?C did notmodify the phase of the rhythm, although a step from 15 to 30?Cor from 30 to 15?C evoked a distortion in the wave form withoutintroducing any reproducible phase shift. Various periods of 9 or 4?C given during the subjective dayphase reduced the pace of rhythm progress by 40 or 60%, whilethose given during the subjective night phase did not. Theseresults suggest that the subjective day and night phases arethe energy charge and discharge phases for the underlying oscillator,respectively. Energy fluxes for the oscillators are brieflydiscussed.
1Present address: National Institute for Basic Biology, Okazaki444, Japan.
2Present address: Aichi Gakuin University, Chikusa, Nagoya 464,Japan. (Received August 25, 1979; ) 相似文献
97.
The energy relationships of the potassium uptake rhythm in aflow-medium culture of a duckweed, Lemna gibba G3, were investigated. Respiratory inhibitors or uncouplers (NaCN, 2,4-dinitrophenoland carbonyl-cyanide m-chlorophenylhydrazon) reduced the mesoror the average rate of potassium uptake, without remarkablydecreasing the amplitude of the rhythm. NaN3, however, preferablysurpressed the amplitude at a concentration as low as 106M. Both dichloro-phenyldimethylurea and the removal of CO2 graduallydecreased the average rate of the uptake, although the rhythmicityitself was not eliminated completely in the absence of CO2.In N2, the average rate of uptake was reduced to zero, but rhythmwith a small amplitude survived. These observations suggested that respired photosynthates provideenergy for sustaining the average of potassium uptake and thatsome light dependent processes control the amplitude of therhythm. Exogenous sugar could make the potassium uptake rhythmappear for a relatively short time in the dark.
1This study was carried out in the National Institute for BasicBiology and the Biological Institute, Faculty of Science, NagoyaUniversity (Received October 24, 1979; ) 相似文献
98.
John A. Rupley Leslie S. Forster Takao Torikata Robert E. Johnson Clifford C. ONeal 《Biochemical and biophysical research communications》1980,93(3):654-660
Equilibrium, thermochemical, and time-resolved fluorescence measurements have been carried out in order to compare pig heart lactate dehydrogenase (LDH) and cytoplasmic malate dehydrogenase (MDH). The differences in the thermodynamic parameters for binding of NADH and NAD+ show the same pattern for both enzymes. The stronger binding of NADH is entropy-based, which can be understood as reflecting electrostatic interactions. The tryptophan fluorescence of MDH and LDH differ for the free enzymes and in quenching by NADH. The differences can be accounted for in terms of a single long-lived tryptophan residue present in LDH and not in MDH. 相似文献
99.
A collagenase, active against native helical collagen, was initially found in the explant medium of bovine dental pulp. In contrast to the collagenases from other oral tissues, all the pulp enzyme released was in a latent form which was activated by trypsin treatment, 4-aminophenylmercuric acetate, and some chaotropic agents. The activated enzyme was inhibited by low concentrations of EDTA and calf serum. The molecular weight of activated enzyme was tentatively estimated at 45,000 daltons by gel filtration. The enzyme attacked undenatured collagen in solution at 20°C producing characteristic products and . 相似文献
100.
As a continuation of previous papers [Biopolymers (1976) 15 , 879; (1978) 17 , 1508], the low-frequency dielectric relaxation of DNA solutions was studied with a four-electrode cell and the simultaneous two-frequency measurement. Below a critical concentration, the dielectric relaxation time agrees with the rotational relaxation time estimated from the reduced viscosity and is almost independent of DNA concentration Cp, and the dielectric increment is proportional to Cp. The critical concentration is approximately 0.02% of DNA for molecular weight Mr 2 × 106 and 0.2% for Mr 4.5 × 105 in 1 mM NaCl. Dielectric relaxations are compared for samples before and after deproteinization, and the protein contamination is found to have a minor effect on the dipole moment of DNA. The effect of a mixed solvent of water and ethanol on the dielectric relaxation of DNA is well interpreted in terms of changes in viscosity and the dielectric constant of the solvent, assuming that the relaxation arises from rotation of the molecule with a quasi-permanent dipole due to counterion fluctuation. 相似文献