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1.
Hideaki Naoe Tatsuyuki Chiyoda Jo Ishizawa Kenta Masuda Hideyuki Saya Shinji Kuninaka 《Biochemical and biophysical research communications》2013,430(2):757-762
Differentiation of placental trophoblast stem (TS) cells to trophoblast giant (TG) cells is accompanied by transition from a mitotic cell cycle to an endocycle. Here, we report that Cdh1, a regulator of the anaphase-promoting complex/cyclosome (APC/C), negatively regulates mitotic entry upon the mitotic/endocycle transition. TS cells derived from homozygous Cdh1 gene-trapped (Cdh1GT/GT) murine embryos accumulated mitotic cyclins and precociously entered mitosis after induction of TS cell differentiation, indicating that Cdh1 is required for the switch from mitosis to the endocycle. Furthermore, the Cdh1GT/GT TS cells and placenta showed aberrant expression of placental differentiation markers. These data highlight an important role of Cdh1 in the G2/M transition during placental differentiation. 相似文献
2.
The medium of 12-day-old culturs of tobacco cells (Nicotianatabacum L., var Xanthi; line XD-6S) contain c.a. 160mg/literof protein, of which 14% of the constituent ami no acids werefound to be hydroxyproline. By sequential column chromatographiesand CsCl density-gradient centrifugation, a basic hydroxyproline-richglycoprotein was purified from the medium and found to havean amino acid composition typical of extensin; with a high levelof hydroxyproline (33mole%), tyrosine (13%), and lysine (14%).The glycoprotein contained 42% (w/w) of sugars, among whicharabinose was the major component (85%). The proportion of thisextensin in the proteins in the culture medium was estimatedto be much higher than that of arabino-galactan protein (about5 times higher) on a protein basis, with extensin comprisingbetween 25% and 41%, and probably about 37% of the proteinsin the medium. (Received September 19, 1988; Accepted December 26, 1988) 相似文献
3.
Localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats An immunohistochemical study 总被引:1,自引:0,他引:1
Dr. Shinji Tamura Sumio Kawata Mitsuhiro Okamoto Seiichiro Tarui 《Cell and tissue research》1988,252(2):397-401
Summary Immunohistochemical localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats was studied by indirect fluorescent antibody staining technique. A polyclonal antibody for cytochrome P-450MC purified from hepatic microsomes of 3-methylcholanthrene-pretreated rats was used for this experiment. A strong immunofluorescence was found to be localized in the cytoplasm of the surface epithelium of the mucosa in the colon of 3-methylcholanthrene-pretreated rats. A faint immunofluorescence was also observed in the epithelium of untreated rats. 7-Ethoxycoumarin O-deethylase activity of colonic microsomes was significantly enhanced by 3-methylcholanthrene-pretreatment in parallel with an increase in the intensity of immunostaining for cytochrome P-450MC in Western blotting analysis. This is the first report on the localization of cytochrome P-450 in the colonic mucosa. 相似文献
4.
Cortical microtubules (MTs) in protoplasts prepared from tobacco (Nicotiana tabacum L.) BY-2 cells were found to be sensitive to cold. However, as the protoplasts regenerated cell walls they became resistant
to cold, indicating that the cell wall stabilizes cortical MTs against the effects of cold. Since poly-l-lysine was found to stabilize MTs in protoplasts, we examined extensin, an important polycationic component of the cell wall,
and found it also to be effective in stabilizing the MTs of protoplasts. Both extensin isolated from culture filtrates of
tobacco BY-2 cells and extensin isolated in a similar way from cultures of tobacco XD-6S cells rendered the cortical MTs in
protoplasts resistant to cold. Extensin at 0.1 mg·ml−1 was as effective as the cell wall in this respect. It is probable that extensin in the cell wall plays an important role
in stabilizing cortical MTs in tobacco BY-2 cells. 相似文献
5.
Hisao Kurazono Shinji Yamasaki Orn-anong Ratchtrachenchai G. Balakrish Nair Yoshifumi Takeda 《Microbiology and immunology》1996,40(4):303-305
Vibrio cholerae O139 isolated from different countries, as well as from different locations within a country, were examined using macrorestriction DNA analysis to determine the clonality of the O139 strains. NotI digests of genomic DNA of representative strains from Nepal, India, Bangladesh, China, Thailand, and Malaysia revealed very similar but not identical patterns. Examinations of the banding patterns generated by pulsed-field gel electrophoresis of strains isolated within countries revealed complete homogeneity. These results further reiterate the spread of an identical clone of V. cholerae O139 although it appears that genetic polymorphism among the O139 strains is becoming apparent. 相似文献
6.
Shinji Yamasaki Zaw Lin Hiromasa Shirai Akito Terai Yuichi Oku Hideaki Ito Mari Ohmura Tadahiro Karasawa Teizo Tsukamoto Hisao Kurazono Yoshifumi Takeda 《Microbiology and immunology》1996,40(5):345-352
To identify the type of Verotoxins (VT) produced by Verocytotoxin-producing Escherichia coli (VTEC), a sensitive bead-enzyme-linked immunosorbent assay and polymerase chain reaction with common and specific primers to various VTs (VT1, VT2, VT2vha, VT2vhb, and VT2vp1) were developed. Together with colony hybridization tests with oligo- and polynucleotide probes, these methods were applied to VTEC isolates to type the VT produced. The toxin types of 26 of 37 strains were identified, but the reaction profiles in assays of the remaining 11 strains suggested the existence of new VT2 variants. The application of these identification procedures may be useful as a tool for clinical and epidemiological studies of VTEC infection. 相似文献
7.
Shiraha H Koide N Hada H Ujike K Nakamura M Shinji T Gotoh S Tsuji T 《Biotechnology and bioengineering》1996,50(4):416-421
We designed a bioartificial liver support system in which encapsulated multicellular spheroids of rat hepatocytes were utilized as a bioreactor in a hollow fiber cartridge. The spheroids, formed in a positively charged polystyrene dish that contained hormonally defined medium, were encapsulated into microdroplets of agarose that contained about 9 x 10(7) rat hepatocytes. The medium, including 150 mL reservoir volume, was circulated in a closed circuit in which the cartridge was inserted. The pH and levels of dissolved oxygen were monitored and automatically regulated so that they were maintained within a constant range for 72 h. Albumin accumulated in the circuit at the rate of 2.0 mg/L/h in this system. When the bioreactor cells in the system were replaced with Hep G2 cells, a human hepatoblastoma cell line, albumin accumulated at the rate of 0.15 mg/L/h. The spheroids of primary culture hepatocytes had 13 times higher albumin-producing capacity than the aggregates of Hep G2. The serum of a patient with fulminant hepatic failure was circulated in this system with the spheroids of primary culture hepatocytes. The concentration of branched amino acid (BCAA) in the circuit significantly increased during the 48 h circulation, while the concentration of aromatic amino acid (AAA) and methionine decreased. The ratio of BCAA/AAA increased from 0.640 to 0.772, indicating that the hepatocyte spheroids had improved the imbalance of the amino acid profile in the serum. These findings indicate that this system may be a useful model for an artificial liver support. (c) 1996 John Wiley & Sons, Inc. 相似文献
8.
Shinji Tokuyama Hiroyuki Miya Kazunori Hatano Takeshi Takahashi 《Applied microbiology and biotechnology》1994,40(6):835-840
A novel enzyme, N-acylamino acid racemase, was purified to homogeneity from Streptomyces atratus Y-53 and characterized. This enzyme catalyzes the interconversion of optically active N-acylamino acids. The relative molecular mass (Mr) of the enzyme was estimated to be about 41 000 and 244 000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration, respectively, indicating that the enzyme is composed of six subunits with an equal Mr. The enzyme showed a broad substrate specificity toward N-acylamino acids, such as N-acetylmethionine, N-chloroacetylphenylalanine and N-chloroacetylvaline. The apparent Michaelis constant (Km) values for N-acetyl-l-methionine and N-acetyl-d-methionine were calculated to be 15.2 and 5.6 mm, respectively. Enzyme activity was markedly enhanced by divalent metal ions, such as Co2+, Mg2+ and Mn2+, and was inhibited by metal-chelating reagent, indicating that the enzyme is a metalloenzyme. We propose to name the enzyme N-acylamino acid racemase (acylamino acid racemase).
Correspondence to: S. Tokuyama 相似文献
9.
Taishin Nomura Shunsuke Sato Shinji Doi Jose P. Segundo Michael D. Stiber 《Biological cybernetics》1994,72(1):55-67
The Bonhoeffer-van der Pol (BVP) oscillator is a valuable dynamical system model of pacemaker neurons. Isochrons, phase transition curves (PTC), and two dimensional bifurcation diagrams served to analyze the neuron's response to periodic pulse stimuli. Responses are described and explained in terms of the nonlinear dynamical system theory. An important issue in the generation of spikes by pacemaker neurons is the existence of both slow and fast dynamics in the state point's trajectory in the phase plane. It is this feature in particular that makes the BVP oscillator a faithful model of living pacemaker neurons. Comparison of the model's responses with those of a living pacemaker was based also on return maps of interspike intervals. Analyzed in detail were the complex discharges called stammering which involve interspike intervals that arise unpredictably and exhibit histograms with several modes separated by the equal intervals.Supported by Trent H. Wells Jr. Inc. 相似文献
10.
Chunyu Cao Hisao Kurazono Shinji Yamasaki Keiko Kashiwagi Kazuei Igarashi Yoshifumi Takeda 《Microbiology and immunology》1994,38(6):441-447
The gene encoding a Verotoxin 2 variant, VTvp1, was mutated by oligonucleotide-directed site-specific mutagenesis. Among 6 mutant toxins encoded by the mutated genes, E167Q-R170L (glutamic acid at position 167 and arginine at position 170 from N-terminus of the A subunit were replaced by glutamine and leucine, respectively) was found to have markedly decreased activities; inhibition of protein synthesis, Vero cell cytotoxicity and mouse lethality of the purified E167Q-R170L were 1/1,900, 1/125,000 and 1/2,000, respectively, of those of the purified wild-type VT2vp1. Since the antigenic property of the E167Q-R170L was demonstrated to be similar to that of the wild-type VT2vp1 by Ouchterlony double gel diffusion test and by neutralization test of Vero cell cytotoxicity of the VT2vp1, a possibility to use the mutant VT2vp1, E167Q-R170L, as a toxoid is discussed. 相似文献