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51.
Outer and inner follicle cell-enclosed oocytes (oocyte complexes) of Halocynthia roretzi underwent germinal vesicle breakdown (GVBD) within 2 hr when transferred from ovaries to normal seawater of pH 8 (NSW). Extrusion of test cells (TC) into the perivitelline space and elevation of the chorion also occurred. This phenomenon was designated as spontaneous oocyte maturation.
Seawater of low pH, protease inhibitors such as leupeptin or soybean trypsin inhibitor (SBTI), and calcium deficiency inhibited the spontaneous maturation only when introduced to the NSW during the first 10 minutes of incubation. GVBD-blocked complexes underwent GVBD after addition of trypsin regardless of pH or the absence of calcium ions. The oocytes from which follicle cells were removed with glycosidase did not undergo GVBD in NSW, but addition of trypsin triggered GVBD in these defolliculated oocytes (TC oocytes). Furthermore, incubation media in which spontaneous maturation had occurred, induced GVBD in the TC oocytes. This GVBD-inducing activity was heat-labile and was inhibited by leupeptin.
These results indicate that in the first step of the spontaneous oocyte maturation, outer and/or inner follicle cells give a signal to the oocyte itself or TC oocyte. This signal is likely to be trypsin-like. 相似文献
Seawater of low pH, protease inhibitors such as leupeptin or soybean trypsin inhibitor (SBTI), and calcium deficiency inhibited the spontaneous maturation only when introduced to the NSW during the first 10 minutes of incubation. GVBD-blocked complexes underwent GVBD after addition of trypsin regardless of pH or the absence of calcium ions. The oocytes from which follicle cells were removed with glycosidase did not undergo GVBD in NSW, but addition of trypsin triggered GVBD in these defolliculated oocytes (TC oocytes). Furthermore, incubation media in which spontaneous maturation had occurred, induced GVBD in the TC oocytes. This GVBD-inducing activity was heat-labile and was inhibited by leupeptin.
These results indicate that in the first step of the spontaneous oocyte maturation, outer and/or inner follicle cells give a signal to the oocyte itself or TC oocyte. This signal is likely to be trypsin-like. 相似文献
52.
Kazuhiro Watanabe Kaori Takanashi Susumu Imaoka Yoshihiko Funae Sumie Kawano Katsuhiro Inoue Tetsuya Kamataki Hidetoshi Takagi Itsuo Yoshizawa 《The Journal of steroid biochemistry and molecular biology》1991,38(6):737-743
For identification of microsomal cytochrome P-450 (P-450) enzymes which catalyze 2- or 4-hydroxylations of estrogens in the rat liver, estradiol (E2) and estradiol 17-sulfate (E2-17-S) were selected as the substrates and incubated with various kinds of purified P-450 enzymes: PB-1, PB-2, PB-4 and PB-5 obtained from phenobarbital-treated male rats (Sprague-Dawley); MC-1 and MC-5 from 3-methylcholanthrene-treated male rats; and UT-1, UT-2, UT-4 and UT-5 from untreated animals. The reactions were carried out under the P-450-reconstructed system, and the resulting products were determined by HPLC using electrochemical detection. All the enzymes tested were shown to have varying degrees of catalytic activities for 2-hydroxylation of the two substrates; UT-1 and UT-2 had the highest activity. Of the induced P-450 enzymes, PB-2 and MC-1 showed fairly high catalytic activity for 4-hydroxylation of E2. The P-450 enzymes obtained from the untreated male rats, especially UT-4, showed the highest catalytic activity for 4-hydroxylation of the two substrates. From these results and also from kinetic experiments, the P-450 enzymes which catalyze 2- and 4-hydroxylations of estrogen were considered to be different species. A part of E2 was converted to such metabolites as estrone and those having a hydroxyl group at positions 6β, 15 or 16, each production of which was estimated to be catalyzed by single or multiple P-450s. 相似文献
53.
Fission Yeast DNA topoisomerase II (165 kD) consists of an enzymatically active 125-kD core, approximately 10-kD NH2-terminal and 30-kD COOH-terminal domains. The question addressed in the present study is what is the role of the topo II termini. Although deletion of either the NH2 or the COOH terminus is viable, deletion of both termini is lethal; the termini share an essential role for viability. We show here that topo II phosphorylation sites are localized in the terminal domains, but dephosphorylated topo II is still active. The topo II terminal sequences are required for nuclear localization; topo II double terminal deletion mutants are deficient for nuclear targeting, whereas wild-type and single deletion mutant topo IIs are transported into the nucleus with different efficiencies. Functional subdomains in the NH2 terminus are further dissected; we identified a 15 amino acid nuclear localization sequence (NLS) which is essential for viability and nuclear localization when the COOH terminus is deleted. This NLS could be substituted with SV-40 large T-antigen NLS. Two other functional subdomains were found; a non-essential acidic stretch which is phosphorylated and apparently enhances the nuclear localization and an essential hydrophilic stretch of unknown function. Motifs similar to these three NH2-terminal subdomains are also found in the COOH terminus. Our results support the possibility that phosphorylation of topo II does not play an essential role in fission yeast. 相似文献
54.
Kazuhiro Nakamura Yasuhiro Goto Naoko Yoshie Yoshio Inoue 《International journal of biological macromolecules》1992,14(6):321-325
It was found that an optically active copolyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), denoted as P(3HB-co-3HV), is synthesized by Alcaligenes eutrophus H16 from several amino acids under various fermentation conditions. The optimum condition for the biosynthesis from one amino acid, threonine, was investigated and its biosynthetic pathway was discussed on the basis of the relation between the fermentation condition and the co-monomer composition of the produced polyesters. 相似文献
55.
Effect of erythroid differentiation factor on megakaryocytic differentiation of L8057, a murine megakaryoblastic leukemia cell line. 总被引:3,自引:0,他引:3
M Nishimura K Kaku Y Azuno K Okafuji Y Etoh M Shiozaki H Sasaki T Inoue T Kaneko 《Biochemical and biophysical research communications》1991,181(3):1042-1047
To assess the potent effect of erythroid differentiation factor (EDF) on megakaryocytopoiesis, effect of EDF on megakaryocytic differentiation of L8057, a murine megakaryoblastic cell line, was examined. EDF potentiated AchE induction of L8057 in a dose dependent manner. The potency of EDF on megakaryocytic differentiation is comparable to that on erythroid differentiation reported previously. The present results suggest that EDF may play a regulatory role in megakaryocytopoiesis as well as in erythropoiesis. 相似文献
56.
Takeshi Shimomura Toshiyuki Honda Chiharu Oouchi Jun Kondo Kazuhiro Nagaike 《Cytotechnology》1991,6(1):1-11
The recombinant human apolipoprotein E (Apo-E) produced by Chinese hamster ovary cells (CHO-322 cells) in serum free culture was degraded to 24K and 23K fragments that contained N-terminal amino acid. The degradation site of Apo-E to 24K fragment was between Arg180 and Leu181 and the C-terminal amino acid of 23K fragment was Gly169. In fetal bovine serum (FBS)-containing culture, the degradation was inhibited. However, in calf serum (CS) the inhibitory activity was not detected. Thus, we attempted the purification of the factor with this inhibitory activity from FBS. A protease inhibitor was purified to give a single peak from FBS by ammonium sulfate precipitation and combination of several column chromatographies. When this FBS-derived protease inhibitor (FBS-d-PI) was added to serum-free culture of CHO-322 cells, degradation of recombinant Apo-E to the 24K and 23K fragments was dose-dependently suppressed and accumulation of intact Apo-E in culture supernatant was observed. FBS-d-PI was found to be a glycoprotein with relative molecular size of 75K daltons under reducing condition, and 85K daltons under nonreducing condition by SDS-PAGE. A complex of FBS-d-PI and a cellular protease was also detected in culture supernatant by western blot analysis using mouse monoclonal antibodies against FBS-d-PI. 相似文献
57.
A new catshark,Scyliorhinus tokubee sp. nov., is described based on specimens from the coast of Shirahama, eastern Izu Peninsula, southern Japan. The present species is distinguished from other congeners in having a particular coloration with dark saddles, blotches and numerous small light spots, a wide oral cleft, the anterior nasal flap not reaching the oral cleft, a short interspace between the dorsal fins, developed clasper hooks, and some meristic characters (number of vertebrae, jaw teeth, and spiral valve turns). This species has been bred under captivity for several years in Shimoda Floating Aquarium. 相似文献
58.
59.
Toshiharu Nagatsu Kazuhiro Oka Takeshi Kato 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1979,163(3):247-252
A highly sensitive assay for tyrosine hydroxylase (TH) activity by high-performance liquid chromatography (HPLC) with amperometric detection was devised based on the rapid isolation of enzymatically formed DOPA by a double-column procedure, the columns fitted together sequentially (the top column of Amberlite CG-50 and the bottom column of aluminium oxide). DOPA was adsorbed on the second aluminium oxide column, then eluted with 0.5 M hydrochloric acid, and assayed by HPLC with amperometric detection. d-Tyrosine was used for the control. α-Methyldopa was added to the incubation mixture as an internal standard after incubation. This assay was more sensitive than radioassays and 5 pmol of DOPA formed enzymatically could be measured in the presence of saturating concentrations of tyrosine and 6-methyltetrahydropterin. The TH activity in 2 mg of human putamen could be easily measured, and this method was found to be particularly suitable for the assay of TH activity in a small number of nuclei from animal and human brain. 相似文献
60.
Kazuhiro Haraguchi Shigeru Saito Hiromichi Tanaka Tadashi Miyasaka 《Nucleosides, nucleotides & nucleic acids》2013,32(2-4):483-493
Abstract Pummerer-type rearrangement of uracil nucleosides having a phenylseleno group in the 2′-, 3′-, and 5′-positions took place upon oxidation with MCPBA in CH2Cl2 followed by treatment with acid anhydrides to yield α-acyloxyselenides. 相似文献