• Proceedings of the Korean Society of Grassland Science Conference
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• 2003.06a
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• pp.174-175
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• 2003

• Korean Journal of Microbiology
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• v.26 no.3
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• pp.215-222
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• 1988

The effect of ammonia and glutamine on nitrogenase activity of Rhodopseudomonas sphaeroides was examined. The nitrogenase activity of this strain was inhibited by ammonia and glutamine. When ammonia and glutamine were exhausted, nitrogenase activity promptly resumed at its original rate. Methionine sulfoximine (MSX), irreversible glutamine synthetase (GS) inhibitor, is a structural analogue of glutamate. MSX was used in order to know whether the nitrogenase activity was inhibited by ammonia and glutamine directly or not. The ability of MSX to prevent nitrogenase switch-off by ammonia was found to be dependent upon the phase of culture. When the cells were sampled after 12 hour culture, $500{\mu}M$ MSX would not prevent the nitrogenase switch-off by ammonia. Twenty one percents of GS actibity was inhibited by $500{\mu}M$ of MSX and concentration of released ammonia decreased. But nitrogenase activiy was still inhibited by ammonia. However, nitrogenase switch-off after 20 hours would be prevented by $100{\mu}M$ of MSX. On the other hand, GS activity was ingibited completely by $100{\mu}M$ MSX and concentration of released ammonia somewhat increased. But nitrogenase activity was not inhibited. The data indicated that the inhibition of in vivo nitrogenase actibity of Rp. sphaeroides by ammonia seemed to be mediated by products of ammonia assimilation rather than by ammonia itself.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.219.2-219
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• 1999

No Abstract, See Full Text

• Proceedings of the PSK Conference
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• 2001.04a
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• pp.156.1-156.1
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• 2001

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.98-105
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• 1989

The examination to find out how the activity of glutamine synthetase (GSA) develop in each wheat leaves during the growth period was carried out. GSA/g FW/leaf were very low at leaf differentiation stage and increased highly several times by unfolding and development of leaf, and declined deeply with the advance of senescence in each leaves. GSA/g FW/leaf were risen gradually from the every lower leaves to the every upper leaves, in consequence activity level and maximum peak per g fresh weight of 7th-flag leaves were two or three times higher than those at the 1st-4th leaves in all of 12 applied nitrogen treatments, thereupon. the highest activities per g fresh weight showed in the 8th leaves. GSA/g FW/leaf was shown two peaks in the 6th-flag leaves and one peak in 1st-4th leaves, respectively. GSA/g FW/leaf (except for senescence leaves) and GSA/plant were increased gradually to the infloresscence emerging stage and were shown the first maximum peak at 13 days before anthesis, then were declined rapidly. to the milk ripe stage (7 days after anthesis). and were shown the second maximum peak at the early dough ripe stage (22 days after anthesis) .

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.212-212
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• 1996

Effects of ginseng total saponin(GTS) on changes in the glutamatergic nervous system induced by AF64A were studied in rats. Rats were pretreated with the infusion of AF64A (3mM) into lateral ventricle and were posttreated with GTS (50mg/kg, j.p) for 1 week. Twenty four hrs after the last administration, rats were sacrified and each brain resions was dissected ; striatum, hippocampus and frontal cortex. At each brain regions, total glutamate and other amino acids levels, [$^3$H]MK801 binding sites and glutamine synthetase activity were measured using HPLC-ECD, ligand binding assay and enzyme activity assay, respectively. The AF64-induced increase in the levels of total glutamate in hippocampus were significantly decreased by the administration of GTS. Furthermore, that compared with saline and GTS was decreased in striatum. The levels of total GABA compared with saline and GTS were declined in frontal cortex. Moreover, the AF64A-induced decrease in the levels of total taurine were significantly increased by the administration of GTS to extents of normal states. The numbers of [$^3$H]MK801 binding sites were differently affected in brain resiojns ; the decrease in hippocampus and no change in both striatum and frontal cortex, Glutamine synthetase activity was significantly increased in hippocampus. In comparision with saline and GTS, that was significantly decreased in striatum These results suggest that GTS may adjust the levels of glutamate, GABA and taurine constantly and may induce increase of glutamine synthetase activity declined.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.5
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• pp.468-475
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• 1992

In order to understand more clearly the integration between N-assmilation and C-metabolism in relation to N fertilization, a pot experiment with 5 different level of N fertilization(0, 5, 10, 25, 50 mM NO$_3$$_{[-10]}$ ) was conducted in Manchester, U.K. The peas (Pisum sativum L., cv. Early Onward) were sown in vermiculate (5 cm depth) and cultivated for 6 days under temperature controlled dark room conditions ($25^{\circ}C$). The plants received frequent irrigation with a nutrient solution: it was fertilized every 2 days, 3 times a day at 10h, 13h, 16h respectively. Elevated NO$_3$$^{[-10]}$ concentration, the activity levels of NR, NiR, total GS(crude extract), GS$_2$(plastid) in both root and shoot were increased and reached the peak in 5～25 mM, except NiR specific activity which increased its activity continually until 50 mM NO$_3$$^{[-10]}$ treatment. Total activities of GS (crude extract) in both root and shoot became higher than those of GS$_2$(Plastid), and the activity ratios of total GS in the crude extract and GS$_2$ in the plastids were 3.0 to 4.3 in root, but 3.2 to 10.6 in shoot. It was concluded that the reductants and A TP from OPPP itself should be enough to achieve the high rate of NR, NiR, GS$_1$, GS$_2$ in plant root and shoot for reduction or assimilation of nitrogen, but these enzyme activities might be inhibited by an excess of NO$_3$$^{[-10]}$ influx over the reduction capacity.

• Biomolecules & Therapeutics
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• v.5 no.1
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• pp.36-42
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• 1997

To investigate effects of ginseng total saponin (GTS) on the ethylcholine aziridnium ion (AF64A) -induced glutamatergic nervous system, rats were pretreated with the infusion of AF64A (3 nmole) into lateral ventricle and were posttreated with 50 mg/kg of GTS, i.p., for 1 week. Twenty four hours after the last administration, rats were sacrificed and the levels of glutamate and taurine, [$^3$H]dizocilpine ([$^3$H]MK801) binding sites and glutamine synthetase activity were assessed in striatum, hippocampus and frontal cortex. The levels of striatal glutamate after GTS treatment in rats were decreased. And the levels of glutamate were decreased in striatum and frontal cortex and increased in hippocampus by the infusion of AF64A. However, the AF64A-induced changes of glutamate were returned to the control level by the administration of GTS in striatum, frontal cortex and hippocampus. After the infusion of AF64A, the level of taurine was decreased in striatum and increased in hippocampus. GTS administrations in the AF64A-treated rats restored to the control level of taurine in the decreased striatal level of taurine, but not in the elevated level of hippocampal taurine. The specific [$^3$H]MK801 binding sites in hippocampus was significantly decreased but not in striatum and frontal cortex after the administration of AF64A. Although GTS itself did not affect the specific [$^3$H]MK801 binding sites, GTS administrations in the AF64A-treated rats did decrease the binding sites of (\`H)Mk801 in all examined regions. The activities of striatal glutamine synthetase were decreased after GTS treatment. The activities of striatal glutamine synthetase (GS) were decreased in AF64A-treated groups. However, the decreased striatal GS activities by AF64A were returned to the control level by GTS treatment. Furthermore, GTS administrations in the AF64A-treated rats increased the hippocampal GS activities. The results indicatethat GTS may adjust the levels of glutamate and taurine constantly and may induce increase in AF64A-induced decrease of GS activity. Thus, it suggests that GTS may antagonize changes in central glutamatergic nervous system induced by AF64A. Also it suggests that the actions of GTS may differently affect in the disease state.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1986.12a
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• pp.517.2-517
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• 1986

The regulation of 3 ammonia assimilatory enzymes GDH(glutamate dehydrogenase), GS(glutamine synthetase) and GOGAT (glutamate synthase), have been examined in C. glutamicum for the biosynthesis of glutamate and glutmine. The cell free extracts of 3 kinds of arg, his and trp auxotrophs were investigated the activities of -ketoglutarate dehydrogenase, GDH, GS, and GOGAT on the media cultured with nitrogen excess and limiting conditions. Trp and his howed higher level of glutamate and glutamine than that of parental strain. The inhibition of GS activities by ADP suggested that GS is regulated by energy charge in C. glutamicum. The results with his, trp, glyc, ala, ser, and GMP implied that a system of feedback inhibition were effective. Three enzyme biosynthesis is repressed by nitrogen sources such as trp, pro, glyc, ala, ser and tyrosine.

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.218.1-218
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• 2005