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排序方式: 共有332条查询结果,搜索用时 15 毫秒
1.
Effects of water-soluble matter adhering to rat hairs on fibroblasts were examined. The dialysate of the wash water of rat hairs significantly enhanced the cell proliferation of both diploid human dermal fibroblasts (DHDF) and diploid rat fibroblasts (DRDF). The cell growth-promoting activity was partially purified by a gel filtration column chromatography. The activity permeates through a ultrafiltration membrane (M.W. cut off: 500). Analyses of its chemical nature show that it is soluble in water, dimethyl sulfoxide or acetonitrile, insoluble in other organic solvents examined, stable to heat or pH shock, and resistant to a bacterial protease. 相似文献
2.
Preliminary screening of polycyclic mutagens is achieved within 20 min by using a biomimetic electrode composed of an oxygen electrode and a copper-phthalocyanine membrane. When benzo[alpha]pyrene (0.05 mM) was added to the buffer solution in the presence of 0.98 M hydrogen peroxide, the current of the phthalocyanine electrode decreased. A linear relationship was obtained between the current decrease and the benzo[alpha]pyrene concentration over the range 0.19-0.60 mM. The minimum measurable concentration for benzo[alpha]pyrene was 0.01 mM. Such responses were not obtained for other organic compounds such as alcohol, ether, n-hexane and cyclohexane. The copper-phthalocyanine membrane electrode has selectively detected polycyclic mutagens such as amino acid pyrolysis products. The current decrease was 1.18-1.46 microA when 0.05 mM amino acid pyrolysis products were employed. 相似文献
3.
The present study was carried out to determine whether K+, Mg2+, PO4(3-), and HCO3- in a medium are necessary for inducing the acrosome reaction in ejaculated goat spermatozoa. Washed goat spermatozoa were resuspended in K-1 medium, containing NaCl, KCl, CaCl2, MgCl2, NaH2PO4, and NaHCO3; in K-2 medium, containing NaCl, CaCl2, NaH2PO4, and NaHCO3; in K-3 medium, containing NaCl, CaCl2, and NaHCO3; and in K-4 medium, containing only NaCl and CaCl2, followed by preincubation in a sealed glass tube at 39.5 degrees C for 1, 2, or 3 h. The sperm acrosome reaction was evaluated by the trypan blue-Giemsa method and hamster test. The results were essentially the same in all cases. Following preincubation for 1 h, however, the percentage of acrosome-reacted spermatozoa, the proportion of zona-free hamster eggs penetrated by spermatozoa, and the average number of spermatozoa in the vitellus of these penetrated eggs were low; all values indicated a significant increase with preincubation for 2 and 3 h. The presence of K+, Mg2+, PO4(3-), and HCO3- in the medium thus does not appear necessary for inducing the acrosome reaction in goat spermatozoa, since they can undergo the reaction during preincubation in a simple physiological salt solution containing only NaCl and CaCl2 when preincubated in sealed glass tubes at 39.5 degrees C. 相似文献
4.
Mayumi Shimizu Kazunari Inaba Toyokazu Yoshida Takayoshi Toda Akio Iwashima Toshio Mitsunaga 《Physiologia plantarum》1995,93(1):93-98
Three thiamine-binding proteins of 17-19 kDa (STBP-I, II, and III) were purified from sesame seed (Sesamum indicum L.). Each of the proteins was composed of two subunits of equal molecular mass and each subunit consisted of a large polypeptide and a small polypeptide linked by a disulfide bond(s). They were rich in glutamic acid (or glutamine) and arginine. Their binding activities were optimal at neutral pH. They bound specifically free thiamine but not thiamine phosphates. STBP-I had higher affinity for thiamine than STBP-II or STBP-III. STBP-II and STBP-III bound one molecule of thiamine per molecule, and STBP-I bound 0.5 molecule. The amino acid composition and structure of the STPBs were similar to those of 2S storage proteins. 相似文献
5.
The complete primary structure of a galactose-specific lectin contained in the venom of the rattlesnake, Crotalus atrox, was determined. The lectin is composed of two covalently linked, identical subunits, each consisting of 135 amino acid residues. Under physiological conditions the lectin proved to be highly aggregated. The venom lectin contained 9 half-cystines, 8 of which formed four intrasubunit disulfide bridges (Cys3-Cys14, Cys31-Cys131, Cys38-Cys133, and Cys106-Cys123), while Cys86 was involved in an intersubunit disulfide bridge. Because of the high content of disulfide bridges, the intact lectin was extremely resistant to tryptic digestion. The determined amino acid sequence was found to be homologous with those of the so-called carbohydrate recognition domains of Ca2(+)-dependent-type lectins in animal. Among them, 8 amino acid residues (Cys31, Gly69, Trp92, Pro97, Cys106, Asp120, Cys123, and Cys131) were completely conserved. Leu40, Trp67, and Trp81 were also well conserved. The rattlesnake venom lectin showed high hemagglutinating activity. These results, together with the occurrence of similar lectins in crotalid venoms, suggest that these lectins have evolved in order to make the venom a more effective weapon to capture prey animals. 相似文献
6.
We studied the taxonomic positions of the rapidly growing organism Mycobacterium fortuitum and phenotypically related organisms. We confirmed that "Mycobacterium peregrinum" ATCC 14467T (T = type strain) is genetically independent of M. fortuitum ATCC 6841T by using various DNA hybridization conditions. Strains that were genetically identified as "M. peregrinum" were phenotypically differentiated from M. fortuitum ATCC 6841T. Thus, we propose that "M. peregrinum" should be revived as an independent species, Mycobacterium peregrinum sp. nov., nom. rev. The type strain is strain ATCC 14467. M. fortuitum subsp. acetamidolyticum ATCC 35931T exhibited a high level of DNA relatedness to M. fortuitum ATCC 6841T. The hybridized DNAs maintained stable heteroduplexity at high stringency; thus, we confirmed that M. fortuitum subsp. acetamidolyticum is identical to M. fortuitum ATCC 6841T. We found that M. chelonae subsp. abscessus ATCC 19977T is genetically different from M. chelonae subsp. chelonae NCTC 946T on the basis of the results of quantitative hybridization even under optimal conditions. There was no reason to maintain this organism as a subspecies of M. chelonae. Thus, we propose that M. chelonae subsp. abscessus should be elevated to species status as Mycobacterium abscessus (Kubica et al.) comb. nov. The type strain is strain ATCC 19977. 相似文献
7.
The effect of extraction of weakly bound Ca2+ by low-pH treatment on the O2-evolving apparatus was studied by use of low-temperature electron paramagnetic resonance (EPR) and X-ray absorption spectroscopy. In low-pH-treated PSII membranes, an S2 EPR multiline signal with modified line shape was induced by illumination at 0 degrees C, but its signal amplitude decreased upon lowering the excitation temperature with concomitant oxidation of cytochrome (cyt) b-559 in place of Mn. The half-inhibition temperature for formation of the modified multiline signal was found at -33 degrees C, which was much higher than that for formation of the normal S2 state in untreated control membranes. Signal IIf was normally induced down to -30 degrees C, but its dependence on excitation temperature was different from that for modified S2. This was interpreted as indicating that the low-temperature blockage of modified S2 formation is due to the incapability of electron abstraction from the Mn cluster. The Mn K-edge of X-ray absorption near-edge structure (XANES) spectrum shifted to lower energy by 0.8 eV after low-pH treatment, but the shift was reversed by addition of Ca2+. Upon illumination at 0 degrees C of treated membranes, the K-edge energy was up-shifted by 0.8 eV, but was not upon illumination at 210 K. These results were interpreted as indicating that extraction of weakly bound Ca2+ by low-pH treatment gives rise to structural and functional modulations of the Mn cluster. 相似文献
8.
Structure of genomic DNA for rat platelet phospholipase A2 总被引:2,自引:0,他引:2
A genomic DNA for rat platelet phospholipase A2 was isolated by screening a rat genomic library with oligonucleotide probes based on its published amino acid sequence. The rat platelet phospholipase A2 gene had a total length of about 2.5 kb and contained five exons and four introns. The intron-exon structure of the rate gene was similar to that of human non-pancreatic phospholipase A2. 相似文献
9.
Kenji Maeda Shunsuke Kawaguchi Toshimitsu Niwa Toyokazu Ohki Kaizo Kobayashi 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1980,221(2):199-204
A gas chromatographic—mass spectrometric analysis was used to separate and identify abnormal compounds in the nail of psoriatic patients. The nail was extracted with heated ethanol, and the extract was analyzed with and without trimethylsilylation. Tetradecanoic acid octadecyl ester, hexadecanoic acid octadecyl ester and octadecanoic acid octadecyl ester were first identified in the psoriatic nail, but were not detected in normal nail. 相似文献
10.
Comparisons were made of the renal ornithine transcarbamylase (OTC) activities within different groups of chickens including Japanese native breeds. OTC activities varied markedly within these groups. The Cochin Bantam breed and White Leghorn B line had an especially high activity, about 400 units/g of kidney, in contrast to two Japanese native breeds, Japanese Game (white variety) and Banshuu Gashiwa, and the California Gray breed, which showed a very low activity, the values being almost undetectable. In crossing experiments using the California Gray breed as a tester strain, Cochin Bantam OTC represents a simple autosomal incompletely dominant trait similar to the White Leghorn B line OTC. Kinetic studies using partially purified OTC preparations from the White Leghorn B line and Cochin Bantam breed revealed that both enzymes were identical for a variety of enzymic characteristics. In light of these results, the physiological significance of chick kidney OTC is discussed. 相似文献