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121.
Makoto Takeuchi Shin-ichi Hisanaga Takashige Umeyama Nobutaka Hirokawa 《Journal of neurochemistry》1992,58(4):1510-1516
A microtubule-associated protein (MAP) with a molecular mass of 72-kDa that was purified from porcine brain by using its property of heat stability in a low pH buffer was characterized. Low-angle rotary shadowing revealed that the 72-kDa protein was a rodlike protein approximately 55-75 nm long. The 72-kDa protein bound to microtubules polymerized from phosphocellulose column-purified tubulin (PC-tubulin) with taxol and promoted the polymerization of PC-tubulin in the absence of taxol. Microtubules polymerized by the 72-kDa protein showed a tendency to form bundles of several microtubules. Quick-freeze, deep-etch electron microscopy revealed that the 72-kDa protein formed short crossbridges between microtubules. We performed peptide mapping to analyze the relationship of the 72-kDa protein to other heat-stable MAPs, and the results showed some resemblance of the 72-kDa protein to MAP2. Cross-reactivity with a monoclonal anti-MAP2 antibody further suggested that the 72-kDa protein and MAP2 are immunologically related. To study the relationship between the 72-kDa protein and MAP2C, a smaller molecular form of MAP2 identified in juvenile rat brain, we prepared the 72-kDa protein from rat brain by the same method as that used for porcine brain. The fact that the 72-kDa protein from juvenile rat brain was also stained with our monoclonal anti-MAP2 antibody also suggested that the 72-kDa protein is an MAP2C homologue of the porcine brain. 相似文献
122.
Among the mammalian tachykinins, substance P (SP) has been shown to be the most potent at modulating the response due to nicotinic acetylcholine receptor stimulation of bovine adrenal chromaffin cells. SP-like immunoreactivity has been detected in nerve terminals innervating the adrenal medulla; however, little is known of the presence of other tachykinins in this tissue. In this study, reverse-phase HPLC was used to fractionate peptides in bovine adrenal medullary extracts, and the fractions were analyzed by radioimmunoassay using antisera to SP or neurokinin A (NKA). The results show that both NKA- and SP-like immunoreactivities are present in the adrenal medulla. The presence of neurokinin B is also indicated. The presence of multiple tachykinins in this tissue raises questions as to their functions in the adrenal medulla. 相似文献
123.
Inhibition of soybean lipoxygenase (L-1) and potato 5-lipoxygenase (5-PLO) by the pyrazoline derivatives phenidone and BW755C only occurs after oxidation of these compounds by the peroxidase-like activity of the lipoxygenases. There is a clear relationship between this oxidation and the irreversible inactivation of L-1. The final product of phenidone oxidation by L-1, 4,5-didehydrophenidone, is not responsible of this inactivation, but the species derived from a one-electron oxidation of phenidone plays a key role in L-1 inactivation. In the absence of O2, inactivation of 1 mol of L-1 occurs after the oxidation of 34 mol of phenidone and the covalent binding of 0.8 mol of phenidone-derived metabolite(s) to L-1. In the presence of O2, inactivation of 1 mol of L-1 occurs already after oxidation of 11 mol of phenidone and only involves the covalent binding of 0.4 mol of phenidone-derived metabolite(s) to L-1. A mechanism is proposed for L-1 inactivation by phenidone, which involves the irreversible binding of a phenidone metabolite to the protein and the oxidation of an L-1 amino acid residue (in the presence of O2). 相似文献
124.
Fluorescent microscopy was proved to be effective for structural identification of permineralized plant tissues in calcite
nodules from the Upper Cretaceous of Hokkaido, Japan. A minute, scale-like projection on the bract of a fossil Taxodiaceous
cone is identified as a true ovuliferous scale because it is bordered with a continuous epidermis that exhibits prominent
fluorescence. The presence of the ovuliferous scale suggests that the fossil is aTaiwania archetype. 相似文献
125.
To examine the differences of the growth and reproduction of different-aged plants, 0-, 1-, and 2-year plants ofAmorphophalus konjac were investigated. RGR and daily net production per unit productive part, relative net-production rate (α′), of the 0-year
plant were largest, although NAR was highest in the 2-year plant. This was due to the large LAR of the 0-year plant, owing
to its large SLA. With increase in age, LAR decreased and NAR increased. Thus, it appeared that the age of plant exerts two
opposite effects on dry-matter production. Since these effects cancel each other out, differences in RGR and α′ between the
two older plants were not significant. We estimated that plant size appears to be primarily responsible for these effects.
The 0-year plant showed the least distribution ratio of net production into reproductive (storage) organs, and the highest
productivity of the reproductive part. The ratio of the production of corm to total reproductive-part production, the D-reproduction
index, was independent of age, and critical size in vegetative propagation could not be detected. 相似文献
126.
Takashi Ariizumi Naomi Moriya Hideho Uchiyama Makoto Asashima 《Development genes and evolution》1991,200(4):230-233
Summary Human recombinant activin A, which is identical with erythroid differentiation factor (EDF), was tested for its mesoderm-inducing activity in concentrations from 0.3–50 ng/ml, using ectoderm of Xenopus late blastula (Stage 9) as the responding tissue. At a low concentration of activin A, blood-like cells, mesenchyme, and coelomic epithelium were induced; at a moderate concentration muscle and neural tissue, and at a high concentration notochord. Activin A thus induced all mesodermal tissues in a dose-dependent manner, such that a low dose induced ventral structures and a high dose induced dorsal structures. Activin may act as an intrinsic inducing molecule responsible for establishing the dorso-ventral axis in early Xenopus development.
Offprint requests to: M. Asashima 相似文献
127.
128.
Summary Analysis of the errors caused by a drift in background fluorescence is performed for a fluorescence probe operated in a backscatter
configuration. In some cases, significant errors can result if changes in background fluorophores during the course of fermentation
are not accounted for. It is shown that the probe's sensitivity to background fluorophores must be considered to calibrate
a fluorescence probe properly. 相似文献
129.
Kiyoshi Ohkawa Takashi Hatano Naoko Takizawa Kazue Shinmoto Kyosuke Yamada Makoto Matsuda Koji Takada Yutaka Tsukada 《In vitro cellular & developmental biology. Animal》1992,28(6):449-454
Summary A human yolk sac tumor cell line, TG1, which was established from a testicular yolk sac tumor, was found to replicate continuously
in a chemically defined medium supplemented with Na2SeO3 (ISRPMI). TG1 produced several plasma proteins and growth factors: albumin, alpha-fetoprotein (AFP), ferritin, carcinoembryonic
antigen, beta-2-microglobulin, polyamine, neuron specific enolase, tissue polypeptide antigen, transferrin (Tf), epidermal
growth factor, and platelet derived growth factor. By analysis of lectin (LcHA)-affinity electrophoresis, to examine the microheterogeneity
of carbohydrate chains of synthetic glycoproteins, TG1 cells cultured with ISRPMI produced only LcHA reactive Tf and AFP based
on core fucose attached to asparagine-linkedN-acetylglucosamine residues instead of LcHA-nonreactive Tf and AFP produced by TG1 cells cultured with fetal bovine serum
(FBS)-containing medium.α1-6 Fucosyltransferase activity was significantly greater in the TG1 cells cultured with ISRPMI (39.9±1.5 pmol · h−1 · mg−1 protein) than cultured with FBS-containing media (18.2±1.2 pmol · h−1 · mg−1 protein). These results have indicated that the selective increase ofα1-6 fucosyltransferase occurred when the cells were cultured with the FBS-free synthetic media. 相似文献
130.
Yoshiteru Harada Kunio Tanaka Yasushiro Uchida Akinori Ueno Sachiko Oh-ishi Yamashita Kowa Masataka Ishibashi Hiroshi Miyazaki Makoto Katori 《Prostaglandins & other lipid mediators》1982,23(6)
Injection of γ-carrageenin into t he pleural cavity of rats caused the accumulation of the pleural exudate. When levels of prostaglandins (PGs) and thromboxane (TX) B2 were quantified by gas chromatography-mass spectrometry as their methyl ester (ME)-dimethyllisopropylsilyl (DMiPS) ether or ME-methoxine-DMiPS ether derivatives, 6-keto-PGF1α reached the maximum at 1 hr after carrageenin, then PGE2 and TXB2 showed peaks at 3 hr and waned off before 9 hr. he PGF2α level was kept low, but PGD2, PGE1 and PGF1α were not detected. Aspirin (100 mg/kg, i.p.) significantly decreased the PG and TXB2 levels and suppressed the rate of plasma exudation until 5 hr, but did not at 7 hr, when it was measured by the amount of exuded pontamine sky blue injected intravenously. OKY-025 (300 mg/kg, i.p.), a selective TXA synthetase inhibitor, and tranylcypromine (20 mg/kg, i.p.), a PGI synthetase inhibitor, could not extensively inhibit the accumulation of the exudate. These results suggest that the cyclooxygenase products of arachidonic acid, particularly PGE2, definitely play an important role in the exudation during the first 5 hr. 相似文献