• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.133-141
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• 1995

The effects of allelochemicals from medicinal plants have been studied as photo-synthetic inhibitor for photoautotrophic(PA) cultured cells. The extracts from 9 plant species were used for measuring the physiological effects on the liverwort cultured cell in following areas; germination inhibition, chlorophyll contents, hill activity, cell viability, photosynthetic oxygen evolution,and protein pattern changes on SDS PAGE. Germination inhibitions were detected in all plant after treating with 10% extract. Especially, treatment with 10% extract from Pulsatilla koreana and Aconitum carmichael inhibited germinations completely. Chlorophyll fornation was inhibited completely by treating PA cells with extract of Pulsatilla koreana, whose effect was similar to that of DCMU 10-3M, inhibitor for photosynthetic electron trans-fer. The treatment with extract from Pulsatilla koreana on PA cell showed the highest hill activity and the lowest cell viability among extracts studied. Oxygen releasing has been decreased down to 14-77% after treating with extracts from Pinellia ternata, Araliacont inentaila, Pulsatilla koreana and Vitex rotundifolia. Especially, 60$\mu$l of Pulsatilla koreana extract into 2ml mixture of PA cell inhibit-ed oxygen release up to 50%. Protein bands on SDS-PAGE, 14kD, 31kD, 41kD, 53kD, and 73kD, were not detected after treating Pulsatilla koreana extract on PA cells.

• Journal of Photoscience
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• v.9 no.2
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• pp.373-375
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• 2002

Lhcb genes encoding light-harvesting chlorophyll-a/b binding (LHC) proteins of photosystem (PS) II were comprehensively characterized using the expressed sequence tag (EST) databases in the green alga, Chlamydomonas reinhardtii. The gene family was composed of eight Lhcb genes including four new genes, which were isolated and sequenced. The effects of light intensity on the levels of mRNAs accumulation of multiple Lhcb genes were studied under various conditions. The results indicate that Lhcb genes are coordinately regulated in response to light conditions, and repressed when the input light energy exceeded the requirement for $CO_2$ assimilation. The effects of high light on the expression of the Lhcb genes observed in the presence of an electron transport inhibitor, DCMU, and in mutants deficient in photosynthetic reaction centers suggest the presence of two alternative mechanisms for regulating the genes expression under high-light conditions.

• Applied Biological Chemistry
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• v.33 no.3
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• pp.264-267
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• 1990

Representative synthetic piericidin-like compounds, such as hydroxypyridine and hydroxyquinoline derivatives, which showed high inhibition activity against NADH-ubiquinone oxidoreductase on the respiratory chain revealed good fungicide activity. Especially, hydrolrypyridine ones showed high activity against rice blast (Pyricularia oryzae) and barley powdery mildew (Erysiphe graminis).

• Biomolecules & Therapeutics
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• v.16 no.1
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• pp.1-8
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• 2008

Mitochondria are important sensor of apoptosis. $H_2O_2-induced$ cell death rate was enhanced by serum deprivation. In this study, we investigated whether serum deprivation using 0.5 or 3 % FBS induces apoptotic cell death through mitochondrial enzyme activation as compared to 10 % FBS. Apoptotic cell death was observed by chromosome condensation and the increase of sub-G0/G1 population. Serum deprivation reduced cell growth rate, which was confirmed by the decrease of S-phase population in cell cycle. Serum deprivation significantly increased caspase-9 activity and cytochrome c release from mitochondria into cytosol. Serum deprivation-induced mitochondrial changes were also indicated by the increase of ROS production and the activation of mitochondrial enzyme, succinate dehydrogenase. Mitochondrial enzyme activity increased by serum deprivation was reduced by the treatment with rotenone, mitochondrial electron transport inhibitor. In conclusion, serum deprivation induced mitochondrial apoptotic cell death through the elevation of mitochondrial changes such as ROS production, cytochrome c release and caspase-9 activation. It suggests that drug sensitivity could be enhanced by the increase of mitochondrial enzyme activity in serum-deprived condition.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.183-187
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• 1999

To establish an efficient screening system for new herbicides using plant cultured cells, responses of tobacco photomixotrophic cultured (PH) cells to various herbicides with different modes of action were surveyed by measuring the cell growth and ion conductivity in medium. The cells were cultured in Murashige and Skoog (MS) medium containing 0.7mg/L 2,4-D, 0.3mg/L kinetin and 30 g/L sucrose at $25^{\circ}C$ in the light (100 rpm). Chemicals were treated to suspension cultures of tobacco PH cells at the time of subculture. The cell growth and ion conductivity in the medium were investigated on 12 days after chemical treatment. The ion conductivity assay gave well correlated results to the cell growth inhibition data. The responses of tobacco PM cells were dependent on the modes of action of chemicals tested. Atrazine, an inhibitor of photosynthetic electron transport (PET), strongly inhibited both the cell membrane and cell growth ($IC_{50}$/, about 1 $\mu$M). Butachlor (an inhibitor of cell division), glufosinate (an inhibitor of amino acid biosynthesis), and fluridone (an inhibitor of carotenoid biosynthesis) showed a dose-dependent inhibition. However, Quinclorac, a herbicide with an auxin activity, did not affect the cell growth and ion leakage. These results suggested that tobacco PM cells is suitable materials for the simple screening of new herbicides such as PET, amino acid biosynthesis, ceil division inhibitors by measuring the cell growth and ion conductivity.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.189-200
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• 2005

Biological nitrogen fixation is an important process for academic and industrial aspects. This review will briefly compare industrial and biological nitrogen fixation and cover the characteristics of biological nitrogen fixation studied in Azotobacter vinelandii. Various organisms can carry out biological nitrogen fixation and recently the researches on the reaction mechanism were concentrated on the free-living microorganism, A. vinelandii. Nitrogen fixation, which transforms atmospheric $N_2$ into ammonia, is chemically a reduction reaction requiring electron donation. Nitrogenase, the biological nitrgen fixer, accepts electrons from biological electron donors, and transfers them to the active site, FeMo-cofactor, through $Fe_4S_4$ cluster in Fe protein and P-cluster in MoFe protein. The electron transport and the proton transport are very important processes in the nitrogenase catalysis to understand its reaction mechanism, and the interactions between FeMo-cofactor and nitrogen molecule are at the center of biological nitrogen fixation mechanism. Spectroscopic studies including protein X-ray crystallography, EPR and $M{\ddot{o}}ssbauer$, biochemical approaches including substrate and inhibitor interactions as well as site-directed mutation study, and chemical approach to synthesize the FeMo-cofactor model compounds were used for biological nitrogen fixation study. Recent research results from these area were presented, and finally, a new nitrogenase reaction mechanism will be proposed based on the various research results.

• Applied Biological Chemistry
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• v.34 no.1
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• pp.43-48
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• 1991

New quinoline compounds were designed, synthesized, and examined with submitochondria. Most compounds showed high activity against NADH-ubiquinone oxidoreductase. Inhibition activity was mainly affected by the length of the lipophilic part, regardless of bulkiness or location of a phenyl group in the side chain. The $\beta-methyl$ group was demons)rated to be the optimal functionality on the nuclei of the quinoline derivatives so 4hat either deletion or insertion of a methylene on the group eliminated its activity.

• Advances in Traditional Medicine
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• v.10 no.4
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• pp.239-253
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• 2010

Coenzyme $Q_{10}$ ($CoQ_{10}$, or ubiquinone) is an electron carrier of the mitochondrial respiratory chain (electron transport chain) with antioxidant properties. In view of the involvement of $CoQ_{10}$ in oxidative phosphorylation and cellular antioxidant protection a deficiency in this quinone would be expected to contribute to disease pathophysiology by causing a failure in energy metabolism and antioxidant status. Indeed, a deficit in $CoQ_{10}$ status has been determined in a number of neuromuscular and neurodegenerative disorders. Primary disorders of $CoQ_{10}$ biosynthesis are potentially treatable conditions and therefore a high degree of clinical awareness about this condition is essential. A secondary loss of $CoQ_{10}$ status following HMG-CoA reductase inhibitor (statins) treatment has been implicated in the pathophysiology of the myotoxicity associated with this pharmacotherapy. $CoQ_{10}$ and its analogue, idebenone, have been widely used in the treatment of neurodegenerative and neuromuscular disorders. These compounds could potentially play a role in the treatment of mitochondrial disorders, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, Friedreich's ataxia, and other conditions which have been linked to mitochondrial dysfunction. This article reviews the physiological roles of $CoQ_{10}$, as well as the rationale and the role in clinical practice of $CoQ_{10}$ supplementation in different neurological diseases, from primary $CoQ_{10}$ deficiency to neurodegenerative disorders. These will help in future for treatment of patients suffering from neurodegenerative disease.

• Journal of Photoscience
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• v.5 no.1
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• pp.1-10
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• 1998

The susceptibility of chilling-resistant spinach plants. and of chilling-sensitive squash plants to photoinhibition was compared in terms of the activity of photosystem II, in relation to the deuce of fatty acid unsaturation of chloroplast membrane lipids. From thylakoid membranes of the plants. monogalactosyl diacylgtycerol, digalactosyl diacylglycerol. sulfoquinovosyt diacylglycerol, and phosphatidylglycerol were seperated as major lipid classes. It was found that the content of cis-unsaturated fatty acids of phosphatidylglycerol was greater by 32% in spinach than that in squash. When leaf disks were exposed to light at 5$\circ$C, 15$\circ$C and 25$\circ$C, photochemical efficiency of photosystem II. measured as the ratio of the variable to the maximum fluorescence of chlorophyll, declined markedly in squash plants, as compared to spinach plants. When leaf disks were exposed to strong light in the presence of lincomycin, an inhibitor of protein synthesis in chloroplasts, photoinhibition was accelerated in the two types of plants. Moreover, lincomycin treatment abolished the differences in the degree of susceptibility to strong light, which had been observed between the two types of plants. When the extent of photoinhibition of photosystem II-mediated electron transport was compared in thylakoid membranes isolated from the two types of plants, there were no differences in the degree of inactivation of photosystem II activity. However, when intact leaf disks were exposed to strong light either at 10$\circ$C or at 25$\circ$C, and then were allowed to recover either at 17$\circ$C or at 25$\circ$C in dim light. chilling-resistant plants such as spinach and pea showed marked recovery from photoinhibition, in contrast to chilling-sensitive plants, such as squash and sweet potato. whose recovery was strongly dependent on the temperature. These findings are discussed in relation to the unsaturation of fatty acids in membrane phosphatidylglycerol. It appears that fatty acid unsaturation of membrane lipids accelerates the recovery of photosystem H from photoinhibition, without affecting the photo-induced inactivation process of photosystem II associated with photoinhibition.

• Korean Journal of Weed Science
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• v.18 no.3
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• pp.246-256
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• 1998

The objective of this study was to investigate the cause of anthocyanin accumulation in the corn leaves treated with metsulfuron-methyl. The accumulation of anthocyanin and total sugar was increased with the time after metsulfuron-methyl application and with the greater herbicide concentration as well. The anthocyanin increase was alleviated by the combined treatment of DUMU or the tank-mixture treatment of metsulfuron-methyl, isoleucine and valine. Metsulfuron-methyl could not enhance the anthocyanin formation in the nonchlorophyllous tissue in which photosynthetic carbohydrate production was limited. Upon the exogenous supply of sucrose, however, the contents of anthocyanin was increased in the both chlorophyllous and nonchlorophyllous leaf segment of corn without the herbicide treatment. On the other hand, the herbicide itself did not influence Hill reaction in vitro and photosynthesis electron transport in vivo. The anthocyanin accumulation by metsulfitronmethyl did not occur in the corn mutants deficient in the structural gene of anthocyanin synthesis, but corns deficient in the regulatory gene had the anthocyanin accumulation only in R-r and r-r type. The above results suggest that the purple pigmentation in the corn leaves treated with metsulfuron-methyl is related to the accumulation of photosynthetic carbohydrate which can stimulate the. regulatory gene related to anthocyanin biosynthetic pathway.