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991.
Mammalian cells are extensively used for production of biopharmaceuticals. Most cells used in industry have infinite proliferative capacity, which provides a high number of cells and corresponding productivity. However, infinite cells will continue to multiply even after cell density reaches sufficient levels. This excess proliferation aggravates the culture environment and induces low productivity. Therefore, after cell density reaches sufficient levels, downregulation of proliferation would prevent such aggravation and extend the culture period and improve productivity. To realize such suitable proliferation, we aimed to establish a novel cell line whose proliferation was spontaneously downregulated after reaching a sufficient population level. Mutagenesis using high-energy beam irradiation was used. CHO-DP12 cells were irradiated with 2.5 Gy X-rays and screened with hydroxyurea and 5-fluorouracil to eliminate any cells multiplying after confluence and to concentrate desired mutants. One clone was established and named CHO-M1. Cell cycle analysis indicated that CHO-M1 cells had a similar cell cycle profile in the exponential growth phase, but cells rapidly accumulated in G1 phase just before confluence and did not progress through the cell cycle. This suggested that until confluence, proliferation of CHO-M1 was similar to parental CHO, but after confluence, it was inhibited and under G1 arrest. The specific antibody production rate of CHO-M1 was kept high, even after confluence, while that of parental CHO was drastically decreased in stationary phase. These results suggest that the desired cell line was successfully established and that high-energy beam irradiation could be an efficient mutagenic technique for breeding industrial cells. 相似文献
992.
Yasukiyo Umemura Tadashi Inoue Masamichi Takagi 《Bioscience, biotechnology, and biochemistry》2013,77(7):1269-1273
The aim of this research was to examine the inhibitory effect of aflatoxin B1, one of the most potent hepatocarcinogen, on the translational step in mouse liver. It has been shown that polysomes were released in vitro from microsomal membrane prepared from rat liver by incubation with aflatoxin B1 and that this release of ribosomes was prevented by addition of corticosterone in the incubation medium.In this paper, the same phenomenon was proved to occur in vivo by an improved fractionation methods, in which ribosome-distributions can be analyzed quantitatively, not only between free and membrane-bound states but also between monosomes and polysomes. Administration of aflatoxin B2 to mice induced reductions of membrane-bound ribosomes and polysomes, with concomitant increases of free ribosomes and monosomes in liver. Simultaneous administration of corticosterone prevented this alteration of ribosome-distributions.From these results, it was deduced that a release of polysomes from membrane occurred primarily by administrating aflatoxin, which then caused a shortening of half-life of mRNA on polysomes, resulting in an increase of the amount of monosomes. 相似文献
993.
Keisuke Kitamura Toshio Takagi Kazuo Shibasaki 《Bioscience, biotechnology, and biochemistry》2013,77(9):1837-1844
The acidic and the basic subunits were shown to be present in equimolar amounts in the 11S globulin molecule by the densitometric scanning of the SDS gel and the molecular weight consideration. The four acidic subunits (A1, A2, A3 and A4) were found to be present in the approximate molar ratio of 1:1:2:2. Four basic subunits separated and designated as B1, B2, B3 and B4 based on the relative mobilities in the acidic gel in 7 m urea were found to be present in the approximate molar ratio of 1:1:2:2. The four basic subunits were fractionated in approximately same amounts into three different peaks, peak I (B1 and B2), peak II (B3) and peak III (B4) by CM-Sephadex C–50 column chromatography in the presence of 6 m urea. Three kinds of intermediary subunits of 11S globulin were fractionated with DEAE-Sephadex A–50 in the absence of reducing agents in 6 m urea, and disulfide bonds appeared to participate in the binding between the acidic and the basic subunits in the molar ratio of 1: 1 with the following combinations; A1 and A2 combined with B3, A3 with B1 and B2, and A4 with B4. In view of the above results and molecular weight consideration, a new model of subunit structure was proposed for 11S globulin. 相似文献
994.
Masanosuke Takagi Masanari Mizutani Ichiro Matsuda Sôzaburo Ono 《Bioscience, biotechnology, and biochemistry》2013,77(5):793-796
The alkylation of α, β-unsaturated esters with n-butylbromide gave stereoselectively α-butyl-β, γ-cis-unsaturated esters in the presence of alkali amide in liquid ammonia. On the other hand, the alkylation of β, γ-cis or trans-unsaturated esters afforded α-butyl-β, cis or trans-unsaturated esters with retention of configuration. These alkylations provide a new synthetic method of preparing α-alkyl β, γ-cis or trans-unsaturated esters. 相似文献
995.
A new flocculant for microbial cells was purified by ethanol precipitation and gel chromatography from the culture fluid of Paecilomyces sp. I-1. Isoelectric focusing of the flocculant (PF-101) showed a single band at pH 8.5, and its molecular weight was estimated to be over 300,000 daltons by the ultra-filtration method. The results of elemental analysis, the IR spectrum and investigation of the acid hydrolysate by gas and liquid chromatography and colorimetrie analysis suggested that PF-101 was a polysaccharide composed of galactosamine. About 80% of the galactosamine residues were N-unsubstituted and 8% were N-acetylated. Studies on deaminative cleavage, periodate oxidation and Smith degradation suggested that the galactosamine residues were mainly linked by α (→4)-linkaees. 相似文献
996.
Yoshikazu Takagi Takane Fujimori Tsuyoshi Hata Hajime Kaneko Kunio Kato 《Bioscience, biotechnology, and biochemistry》2013,77(3):705-706
Glutamine production was investigated by coupling of glutamine synthetase from Gluconobacter suboxydans with a sugar fermentation system of baker's yeast (energy generating system). Under the optimum condition, 22 mM glutamine was formed in 3 hr, and the yield was 92% based on the substrate glutamate. The first step of the process was the accumulation of fructose 1,6-diphosphate (FDP) as a reservoir of fermentation energy, in the presence of a high concentration of inorganic phosphate; and the second step was accomplished by coupling the degradation of FDP with glutamine synthetase reaction through an ADP-ATP system. The effects of enzyme concentration, additives in the reaction mixture and others on glutamine formation were investigated, and the importance of three factors was pointed out: (a) the ratio of activity of energy generating system to utilizing system, (b) contaminated enzyme(s) in the energy utilizing system and (c) the enzymatic properties of the energy utilizing system. 相似文献
997.
998.
Takeshi Kitahara Katsutoshi Miura Yasuhiro Warita Yoshikazu Takagi Kenji Mori 《Bioscience, biotechnology, and biochemistry》2013,77(4):1129-1133
A novel synthesis of ( ± )-methyl epijasomonate (2) and the first synthesis of ( ± )-methyl cucurbate (4) were achieved starting from 2-allylcyclohexane-1,3-dione (8). The synthetic epimer 2 had a stronger jasmin flavor than the trans-isomer 1 with 95% purity. 相似文献
999.
Akihiro Okitani Osamu Takagi Masao Fujimaki 《Bioscience, biotechnology, and biochemistry》2013,77(8):939-946
The process of the denaturation of “myosin B” solution was studied by the measurement of ATPase activity, SH groups, sedimentation behaviour and flow birefringence. When “myosin B” solution was stored at lower temperature, lower pH or higher ionic strength, the interaction between myosin A and actin became less strong, and further storage brought about an irreversible dissociation.The condition for measuring Mg-modified ATPase activity of “myosin B” at low ionic strength was explained in the relation with superprecipitation. 相似文献
1000.
Toshizo Nagasawa Heiji Takagi Kozo Kawakami Takao Suzuki Yoshikazu Sahashi 《Bioscience, biotechnology, and biochemistry》2013,77(6):441-447
Browning of green broad bean appears only in the seed-coat, and not in cotyledon. This phenomenon coincides with the facts that phenolic compounds such as l-tyrosine and 3,4-dihydroxyphenylalanine are localized in the seed-coat tissues. But little is known about the browning mechanism of the seed-coat at present.In this study, the presence of dopa-o-β-d-glucoside was confirmed in addition to those phenolic compounds mentioned above, and the distribution of this substance in tissues of green broad bean was examined by paper chromatography. A clear indication of the relationships between the mechanism of brown pigmentation and the biosynthesis of dopa-o-β-d-glucoside in vivo was also presented. 相似文献