• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.538-543
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• 1994

Effect of partial oxygen pressure on the cell growth and the activities of oxidative defense enzymes were measured in the continuous culture of Streptomyces coelicolor. Both the wild type and the mutant strain resistant to hydrogen peroxide were cultured and the dry cell weight of the two cultures were measured at different oxygen tensions. Growth of the wild type was inhibited by oxygen at above 0.5 vvm. Growth of the hydrogen peroxide resistant mutant was stimulated by pure oxygen at 0.5 vvm but was inhibited by oxygen at 1.0 vvm. Therefore, growth of the hydrogen peroxide resistant mutant was less affected by the deleterious oxidative stress of oxygen. Activities of the several defense enzymes were also measured at different oxygen tensions. Activities of catalase and glucose-6-phosphate dehydrogenase increased significantly as oxygen pressure increased in the wild type culture. In the mutant, however, increase in those enzyme activities was not obvious whereas the uninduced levels of the above enzymes were higher than those of wild type. As judged by Western blotting, the amount of the major catalase increased as the oxygen pressure increased. This indicates that the induction of the catalase activity by oxygen pressure is mostly due to the increase in the expression level for the major catalase.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.2
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• pp.84-91
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• 2000

Mycopasma contamination of tissue culture cells easily evades detection and, thus, represents a continous therat to cell biologists. In case where infected cell can not simply be replaced, attempts have to be made to eradicate mycoplacma from the tissue culture cells. A variety of anti-microbial agents have been shown to be toxic to mycoplasma strains ; however, cell associated mycoplasma are often protected from antibiotics at concentrations shown to be effective in vitro. Antibiotic concentrations high enough to be lethal to cell as sociated mycoplasmas frequently are also detrimentrations to the host cells, while moderately increased antibiotic levels tolerated by the host cells often lead to only temporary growth suppression and/or to the emergence of mycoplasma strains resistanct even to high concentrations of the antibiotis applied. Hare, a genetic approach for the elimination of mycoplasma from tissue culture cells that overcomes thens limitations is described. By expression of a selection marker conferring resistance to an otherwise toxic agent, Acholeplasma laidlawii infected BHK-21 cells used as the model system were enabled to temporarily tolerate antibiotic concentrations high enough to be lethal to cell associated mycopalsma while leaving the host cells unharmed. Upon successful mycoplasma eradicated, cultvation of the cured host cells in the absence of the selective agent yielded revertant cell clones that had regained susceptibillity to the toxic agent. Cressation of the selection marker expression was shown to result from the loss of the selection marker DNA, which is a consequence of the fact that the stable and permanent integration of foreign DNA in eucaryotic cell chrosomes is highly inefficient. Thus, the cells were cured from mycoplasma yet remained biochemically unaltered.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.3
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• pp.187-194
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• 1998

This study was conducted to investigate the effect of antagonistic bacteria and pathogenic fungi on growth and yields of white clover(Trifo1iurn repens L.) in continuous cropping soil(CCS) and non-continuous cropping soil(NCCS). The gowth experiment of white clover was conducted at pots in a vinyl house. White clover was established by seeding into pots of 12 cm in diameter and 9 cm in depth containing 1:l mixture of soil and vermiculite with antagonistic bacteria and pathogenic fungi. In dark culture experiment, white clover lived longer in treatment of antagonistic bacteria than in treatment of control, but lived shorter in CCS than in NCCS. Dry weight of white clover was increased by the inoculation of the antagonistic bacteria(p< 0.05), but decreased by the inoculation of the pathogenic fungi(p< 0.05) both CCS and NCCS. In conclusion, bacterization of white clover with antagonistic bacteria enhances the growth and yield of white clover.

• The Korean Journal of Mycology
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• v.21 no.4
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• pp.323-331
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• 1993

The protoplast formation and intergeneric protoplast fusion between Gliocladium virens and Trichoderma harzianum were attempted to obtain fusants. Protoplast formation was the most effective when the strains were treated with concentration of 5 mg/ml of Novozyme 234 and Cellulase at $25^{\circ}C$ for 3 hours in phosphate buffer, pH 6.5, supplemented with 0.6 M sorbitol as osmotic stabilizer. Auxotrophic mutants of G. virens G88 did not grow in minimal medium and benomyl resistant T. harzianum T95 from wild types, however, was selected by treatment with UV light as genetic marker to isolate fusants. When the intergeneric protoplast fusion between G. virens G88 and T. harzianum T95 was carried out using 30% PEG 4000 containing 10 mM $CaCl_{2}$, and 50 mM glycine (pH 8.5) as fusogenic agent at $25^{\circ}C$ for 10-15 min, the fusion frequency was $0.8{\times}10^{-4}$. Fusants obtained from intergeneric protoplast fusion were spontaneously segregated into va rious strains by continous culture on complete medium. Several intergeneric hybrids were classified into three types: parent-like hybrids, segregants, and recombinants.

• Korean Journal of Plant Tissue Culture
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• v.25 no.3
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• pp.195-200
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• 1998

Callus induction from leaf and stem explants of Arabidopsis thaliana was successfully obtained when leaf explants were cultured on MS medium containing 2.0 mg/L 2,4-D in the dark and also, when stem explants were cultured on CP medium containing 0.5 mg/L 2,4-D and 0.1 mg/L BAP. Explant-derived sliced calli were suspension-subcultured every week in CP liquid medium with 0.5 mg/L 2,4-D and 0.1 mg/L BAP in the dark, and shoot-forming cell clusters of nodular, pale yellow and knobby type were selected after 7-8 weeks of culture. Shoots were initiated from the green spots of the selected shoot forming calli cultured on MS regeneration medium containing 0.05 mg/L IAA, 7.0 mg/L 2-iP and 30 g/L sucrose under continous illumination for four weeks. Shoot regeneration frequency (calli regenerating at least one shoot) was more than 50%. For plant regeneration, excised shoots were trnasferred to hormone free medium for root initiation after 4 weeks of culture. The regenerants were bolting after 2 weeks of culture and formed in vitro flowering buds within bracts after 4 weeks of culture.

• Journal of Digital Convergence
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• v.13 no.10
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• pp.41-50
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• 2015

This study targeted volunteers to identify the variables that affect the attitude for participating in the volunteer activities going forth, and their effect. The independent are consisted of personal characteristic variables, participation related variables, management process variables. As for the dependent variables, they included the will to participate continually and degree of participation. The major findings are as follows : First, volunteer work agency try to activate housewives' participants. Second, the volunteer work agency need to improve and develop the programs which are consisted of more 3-hours per participation and three times per month. Third, so the motivations are the most important variables affect the sustainability, volunteer programs must be established to realize effective experience learning and social participation. Forth, a systematic management for the volunteer programs must be established to activate more participation.

• Journal of Ginseng Research
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• v.27 no.2
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• pp.78-85
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• 2003

By the Agrobacterium rhizogenes A$_4$ were induced a transformed callus of ginseng hairy root and examine to find the possibility whether it can produce certain ginsenoside. Investigations for a finding out to optimal culture medium showed that BA application is better than more factorial composition between auxins and cytokinins. For the induction of hairy root callus of ginseng, l/2 MS medium containing 1 to 3 mg of benzyladenine(BA) per liter gave the best result. The growth of ginseng hairy root callus(GHC) cultured with the 1/2MS medium supplemented with 2 mg BA/L was selected for best suspension cultures. The optimum concentration of BA for ginsenosides production was found to be 2 mg/L. Probably the inoculum size of callus plays a role with the ginsenoside production in suspension culture. AS for inoculum size of callus, 50 mg was superior to 150 mg for growth and ginsenoside production. Ginsenoside contents were highest in the suspension culture grown for four weeks under continuous light condition. In fact that continous light treatment promote strongly the synthesis of ginsenoside of the hairy root callus is first result in the world and the numerously induced root hairs of the callus leads a new method for ginsenoside production.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.902-907
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• 1998

In this study the anaerobic degradation of nitrate by in GFM (gel and foam matrix) and bead gel immobilized Paracoccus denitrificans DSM 65 in continous culture was conducted. A novel GFM immobilization system was developed in order to improve conventional system (bead). With increasing nitrate concentration in water, the nitrate reduction rate was increased. The observed maximum denitrification rate by in GFM immobilized cells was 177 mg/L h in buffered water, while that was 33 mg/L h in tap water. In comparison with bead system the reduction activity by GFM system showed $1.2{\sim}2.1$ times better. The denitrification activity was not changed after 16 days storage at $5^{\circ}C$ and also showed better activity than that of free cells or even bead immobilized cells.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.351-356
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• 1997

This experiment was aimed to find out the measures or soil managements in continuous melon cultivation and to produce the high quality of yellow melon in plastic film house culture. The experiment was designed with surveying of farmer's field and conducted for 4 years. The most effective measure of soil managements was to cultivate paddy rice in June after harvesting the melon and next ways were treated with submergence or the plastic film for 40days during the period of high temperature of summer and plowed over 50cm depth with plough machine. To decrease the soil problems in continous cultivation, the addition of red earth soil of 500M/T per 10a with increasing the application rates of rice straw and fertilizer (N, P, K) in 30% and 10% respectively was effective in plastic film house culture. The effect of soil amendment application was continued for two years at least and it increased the commercial quality and sugar content in brix of yellow melon in 10% and 2.6 degree respectively.

• Korean Journal of Plant Tissue Culture
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• v.26 no.2
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• pp.127-132
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• 1999

Protoplasts were isolated from the leaf mesophyll tissue of in vitro 4-weeks-old Arabidopsis thaliana and cultured in MS liquid medium supplemented with 2.0 mg/L NAA, 0.5 mg/L BAP and 9% mannitol in the dark at $25^{\circ}C$. When protoplast-derived microcolonies were dehydrated, the frequency of callus induction enhanced approximately 7-fold higher compared with non-dehydrated microcolonies in CP medium. Fifty callus lines were selected from dehydrated microcolonies. Shoots were efficiently initiated from the green spots of the selected shoot forming calli cultured on MS regeneration medium supplemented with 0.05 mg/L IAA, 7.0 mg/L 2-iP and 30 g/L sucrose under continous illumination for 4 weeks. Shoot regeneration frequencies (calli regenerating at least one shoot) were 3.5%~56%. Histological observations of shoot forming callus revealed that tracheary elements initiated from inner compact cells, and that meristemoids developed to shoot primordia and shoots. Roots were induced from these regenerating shoots on MS medium without phytohormones. These regenerants were successfully transplanted into potting soil. Morphological characterization of 50 protoplast-derived plants showed that the frequency of normal type was 78%.