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21.
Takafumi Tadano Hiroki Otani Masanori Taira Igor B. Dawid 《Genesis (New York, N.Y. : 2000)》1993,14(3):204-211
Mesoderm development in Xenopus laevis depends on inductive cell interactions mediated by diffusible molecules. The mesoderm inducer activin is capable of redirecting the development of animal explants both morphologically and biochemically. We have studied the induction of four regulatory genes, Mix. 1, goosecoid (gsc), Xlim-1 and Xbra in such explants by activin, and the influence of other factors on this induction. Activin induction of gsc is strongly enhanced by dorsalization of the embryo by LiCl, while expression of the other genes is only slightly enhanced. The protein synthesis inhibitor cycloheximide (CHX) inhibits the activin-dependent induction of Xbra partially, while induction of Mix. 1 and Xlim- 1 is essentially unaffected. In contrast, gsc shows strong superinduction in the presence of activin and CHX, and can be induced in animal explants by CHX alone. Induction and superinduction by CHX have previously been observed for immediate early genes in a variety of systems, notably for the activation of c-fos expression by serum stimulation, but have not been reported in early amphibian embryos. © 1993Wiley-Liss, Inc. 相似文献
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Physical effects of negative air ions in a wet sauna 总被引:10,自引:0,他引:10
I. Watanabe Hiroshi Noro Yoshinori Ohtsuka Yukio Mano Yuko Agishi 《International journal of biometeorology》1997,40(2):107-112
The physical effects of negative air ions on humans were determined in an experimental sauna room equipped with an ionizer.
Thirteen healthy persons took a wet sauna bath (dry bulb temperature 42° C, relative humidity 100%, 10 min exposure) with
or without negative air ions. The subjects were not told when they were being exposed to negative air ions. There were no
differences in the moods of these persons or changes in their blood pressures between the two saunas. The surface temperatures
of the foreheads, hands, and legs in the sauna with negative ions were significantly higher than those in the sauna without
ions. The pulse rates and sweat produced in the sauna with ions were singificantly higher than those in the sauna without
ions. The results suggest that negative ions may amplify the effects on humans of the sauna.
Received: 31 March 1995 / Revised: 25 July 1995 / Accepted: 26 July 1996 相似文献
25.
Michiyoshi Masuda Kimio Isiglo Hideki Yamoka Takafumi Matsumoto Manabu Takahashi 《Biochemical and biophysical research communications》1984,119(3):920-925
The fate of 3H-thymidine incorporated into newly synthesized DNA of CHO cells was analyzed by either the estimation of the incorporated radioactivity per cell or sedimentation in alkaline sucrose gradient. Under conditions in which DNA synthesis proceeded continuously, of incorporated radioactivity was periodically lost and regained during a 90 min chase, corresponding to a cyclic change in the sedimentation profiles. When DNA synthesis was inhibited by hydroxyurea no cyclic change of the incorporated radioactivity was observed. The cyclic changes were regarded as the result of an actual metabolic change in3H-labelled DNA probaly joining to one of the newly formed sister strands of DNA and the loss of radioactivity seems to require active continued DNA synthesis. 相似文献
26.
Studies on transfer ribonucleic acids and related compounds. XL. Synthesis of an eicosaribonucleotide corresponding to residues 35-54 of tRNAfMet from E. coli. 总被引:4,自引:3,他引:1
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An E. coli tRNAfMet fragment [C-A-U-A-A-C-C-C-G-A-A-G-G-U-C-G-U-C-G-G (bases 35-f54)] containing the anticodon triplet has been synthesized by the phosphotriester method involving protected oligonucleotide blocks. Di- or tri-nucleotide blocks were prepared by condensation of 2'-O-(o-nitrobenzyl) nucleotide derivatives and used for the synthesis of pentanucleotide blocks. The 5'-hydroxy, heterocyclic amino and internucleotide linkage were protected with monomethoxytrityl, acyl and p-chlorophenyl groups, respectively. The 3'-phosphates of the pentanucleotides, except for the GUCGG block where 2'-O-benzoyl 3'-O-(o-nitrobenzyl) N-isobutyrylguanosine was used, were protected with p-chlorophenyl and anilido groups. The anilido groups were removed by treatment with isoamyl nitrite and the 3'-phosphodiesters of resulting pentamers were activated with mesitylenesulfonyl nitrotriazolide to give protected decanucleotides in yields of 61-89%. The two decanucleotides were condensed similarly to yield the protected eicosanucleotide in a yield of 59%. The product was deblocked and purified by ion-exchange chromatography on DEAE-Sephadex A-25 and characterized by enzymatic hydrolysis after labelling the 5'-end by phosphorylation using polynucleotide kinase and [gamma-32P]ATP. 相似文献
27.
Masato Hirata Takafumi Hamachi Eiichi Suematsu Toshitaka Koga 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1983,763(4)
Effects of N-formyl chemotactic peptides on the Ca2+ influx and efflux were investigated in guinea-pig peritoneal macrophages using an isotope tracer. fMet-Leu-Phe did not enhance the influx of 45Ca2+ into macrophages, whereas it stimulated the efflux of 45Ca2+ from macrophages at concentrations ranging from 10−10 M to 10−7 M. fMet-Met-Met and fMet-Leu also stimulated the 45Ca2+ efflux, albeit at much higher concentrations, while there was no stimulation with fMet. The mitochondrial inhibitors, oligomycin and NaN3, did not modify the 45Ca2+ efflux induced by the chemoattractants, yet they did induce the release of 45Ca2+ from the mitochondria. On the other hand, higher concentrations of the calmodulin antagonists, chlorpromazine and trifluoperazine, induced the release of 45Ca2+ from the NaN3-insensitive Ca2+ store site and mimicked the enhancement of the 45Ca2+ efflux by N-formyl chemotactic peptides. Thus, N-formyl chemotactic peptides appear to increase the levels of intracellular free Ca2+ in guinea-pig peritoneal macrophages, probably by inducing the release of Ca2+ from the NaN3-insensitive Ca2+ store site. 相似文献
28.
Masato Hirata Takafumi Hamachi Eiichi Suematsu Toshitaka Koga 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1983,763(4):339-345
Effects of N-formyl chemotactic peptides on the Ca2+ influx and efflux were investigated in guinea-pig peritoneal macrophages using an isotope tracer. fMet-Leu-Phe did not enhance the influx of 45Ca2+ into macrophages, whereas it stimulated the efflux of 45Ca2+ from macrophages at concentrations ranging from 10?10 M to 10?7 M. fMet-Met-Met and fMet-Leu also stimulated the 45Ca2+ efflux, albeit at much higher concentrations, while there was no stimulation with fMet. The mitochondrial inhibitors, oligomycin and NaN3, did not modify the 45Ca2+ efflux induced by the chemoattractants, yet they did induce the release of 45Ca2+ from the mitochondria. On the other hand, higher concentrations of the calmodulin antagonists, chlorpromazine and trifluoperazine, induced the release of 45Ca2+ from the NaN3-insensitive Ca2+ store site and mimicked the enhancement of the 45Ca2+ efflux by N-formyl chemotactic peptides. Thus, N-formyl chemotactic peptides appear to increase the levels of intracellular free Ca2+ in guinea-pig peritoneal macrophages, probably by inducing the release of Ca2+ from the NaN3-insensitive Ca2+ store site. 相似文献
29.
T Hakoshima T Itoh K Gohda K Tomita S Uesugi S Nishikawa H Morioka E Ohtsuka M Ikehara 《FEBS letters》1991,290(1-2):216-220
Complex of a mutant ribonuclease T1 (Y4SW) with a non-cognizable ribonucleotide, 2′AMP, has been determined and refined by X-ray diffraction at 1.7 Å resolution. The 2′AMP molecule locates at a new base-binding site which is remote from the guanine-recognition site, where 2′GMP was found to be bound. The nucleotide adopts the anti conformation of the glycosidic bond and C3′-exo sugar pucker. There exists a single hydrogen bond between the adenine base and the enzyme, and, therefore, the site found is apparently a non-specific binding site. The results indicate that the binding of 2′AMP to the guanine-recognition site is weaker than that to the new binding site. 相似文献
30.
An endonuclease activity in human polymorphonuclear neutrophils that removes 8-hydroxyguanine residues from DNA+ 总被引:9,自引:0,他引:9
M H Chung H S Kim E Ohtsuka H Kasai F Yamamoto S Nishimura 《Biochemical and biophysical research communications》1991,178(3):1472-1478
An endonuclease that specifically removes 8-hydroxyguanine (oh8Gua) from DNA has been isolated from Escherichia coli. As the amount of oh8Gua produced in DNA of X-ray-irradiated mice is known to decrease with time after irradiation, an attempt was made to find a similar activity in human polymorphonuclear neutrophils (PMNs) using a synthetic dsDNA containing oh8Gua as a substrate. The PMN enzyme was isolated free of other DNases, and found to cleave the substrate DNA simultaneously at 2 sites, the phosphodiester bonds 5' and 3' to oh8Gua, producing free hydroxyl and phosphate groups, respectively. The enzyme showed almost no activity on DNAs containing other kinds of modified base tested or mismatched DNA. Thus human cells also contain an endonuclease that specifically removes oh8Gua residues from DNA. 相似文献