• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.4
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• pp.297-302
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• 1999

Cotyledonary abnormalities were observed in secondary somatic embryos which were developed from calli cultured on MS medium with various concentrations of 2,4-D. In MS medium containing hormone-free or $0.1mg/{\ell}$ 2,4-D, the frequency of normal embryo formation with two cotyledons were above 57%. According to concentration of 2,4-D increment the frequency of normal embryos were decreased. In MS medium containing $4mg/{\ell}$ 2,4-D, the frequency of normal embryo formation was just 10%. The rate of germination was as follows; 37.7% of somatic embryos had one cotyledon, 85% two cotyledons, 38% three cotyledons, 35% four cotyledons, 25% five cotyledons and 29% trumpet-like cotyledons. About 80% of the embryos with two cotyledons were converted into normal plants, but one, three or four cotyledons were only 6.8~10%. The five or trumpet-like embryos were not developed into normal plants.

• Journal of The Korean Astronomical Society
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• v.55 no.2
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• pp.59-66
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• 2022

Stellar magnetic activity is important for formulating the evolution of the star. To represent the stellar magnetic activity, the S index is defined using the Ca II H+K flux measure from the Mount Wilson Observatory. Mg II lines are generated in a manner similar to the formation of Ca II lines, which are more sensitive to weak chromospheric activity. Mg II flux data are available from the International Ultraviolet Explorer (IUE). Thus, the main purpose of this study was to analyze the magnetic activity of stars. We used 343 high-resolution IUE spectra of 14 main-sequence G stars to obtain the Mg II continuum surface flux and Mg II line-core flux around 2,800 Å. We calculated S index using the IUE spectra and compared it with the conventional Mount Wilson S index. We found a color (B - V ) dependent association between the S index and the Mg II emission line-core flux. Furthermore, we attempted to obtain the magnetic activity cycles of these stars based on the new S index. Unfortunately, this was not successful because the IUE observation interval of approximately 17 years is too short to estimate the magnetic activity cycles of G-type stars, whose cycles may be longer than the 11 year mean activity cycle of the sun.

• Korean Journal of Plant Tissue Culture
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• v.27 no.6
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• pp.461-468
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• 2000

For the enhancement of ginsenoside production in hairy roots cultures of Panax ginseng, the uptake rate of inorganic elements and ginsenoside contents were investigated by different concentrations of about phosphorus (P $O_{4}$$^{[-10]}$ ) and nitrogen (N $H_{4}$$^{+}$, N $O_{3}$$^{[-10]}$ ) sources. According to increased phosphorus and nitrogen sources, the uptake rate of $Mg^{2+}$ and F $e^{2+}$ in ginseng hairy roots were significantly increased. The uptake rate of F $e^{2+}$ in 5.15 mM N $H_{4}$$^{+}$ was higher at 47.5% than that in 20.6 mM, whereas that of C $u^{2+}$ in 10.3 mM were higher at 123.1% than that in 41.2 mM. These results indicated that phosphorus and nitrogen sources act not only elevated growth of hairy roots but also the uptake-enhancement of the irons and other ions. The optimum concentration of phosphorus and nitrogen sources for the contents of free sugars were different to kinds of free sugars. The optimum concentration of phosphorus and nitrogen sources for the ginsenoside formation in ginseng hairy roots cultures were highest at the most low concentration of all. The contents of ginsenoside-R $b_2$and -Rc in 0.31 mM P $O_{4}$$^{[-10]}$ were increased to 44.7% and 29.9% than that in 0.62 mM P $O_{4}$$^{[-10]}$ , respectively. The contents of ginsenoside-R $b_2$ and -Rc in 5.15 mM N $H_{4}$$^{+}$ were increased to 21.7% and 31.9% than that in 10.30 mM N $H_{4}$$^{+}$, respectively. The contents of ginsenoside-R $b_2$and -Rc in 4.7 mn N $O_{3}$$^{[-10]}$ were also increased to 17.6% and 25.5% than that in 9.4 mM N $O_{3}$$^{[-10]}$ , respectively. These results indicate that enhancement of the ginsenoside formation in ginseng hairy roots was feasible by new medium modulation of concentration of phosphorus and nitrogen sources.rogen sources.

• Microbiology and Biotechnology Letters
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• v.50 no.4
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• pp.548-556
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• 2022

Acylases can have a significant effect on biofilm formation owing to their quorum quenching activity. In this study, we investigated the effects of acylase treatment episodes on multispecies biofilm development. A consortium composed of 9 species belonging to different genera was allowed to form biofilms for 5 days under various treatment episodes (different treatment periods, 1, 2, 3, or 4 days; and two application timings, beginning or later) at 1, 5, 10, 20 and 50 mg·l^-1 acylase concentrations. The acylase treatment for 5 days showed that acylase concentration was negative with biofilm development (linear regression, Y = -0.05·x + 2.37, p < 0.05, R² = 0.88). Acylase was more effective in reducing biofilm formation when it was applied in the beginning (vs. in later development stage) at all acylase concentrations (p < 0.05). ANOVA indicated that treatment period was significant on biofilm formation in both application timings at ≥ 10 mg·l^-1 (p < 0.05). Linearity test results showed that all slope values between period and biofilm were negative in both timings at ≥ 10 mg·l^-1 (p < 0.05, except for the later application at 20 mg·l^-1). When temporal biofilm dynamics were monitored at 20 mg·l^-1, biofilms gradually increased with time at all treatment episodes (p < 0.05), and slope values in linear regression between biofilm and time were lower when acylase was applied in the beginning (p < 0.05). Our findings suggest the importance of the acylase treatment period and application timing on biofilm control.

• Journal of the Korean Chemical Society
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• v.25 no.1
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• pp.26-29
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• 1981

Reactions of m-xylene were studied in a fixed-bed type micropulse reactor over cation-exchanged dealuminated mordenite and zeolite Y catalysts. Over H-mordenite catalysts higher catalyst pretreatment temperature as well as dealumination resulted in the increase of the formation of disproportionation product. $Ba^{2+}- and Mg^{2+}-$exchanged mordenite catalysts showed the shape selectivity in the disproportionation reaction of m-xylene, that is, the formation of trimethylbenzene decreasing sharply as the degree of cation exchange increased.

• Journal of Life Science
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• v.31 no.3
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• pp.330-337
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• 2021

This study was conducted to investigate the potential of Stewartia koreana as oral healthcare materials. The antibacterial activity of ethanol extracts from leaves and branches of S. koreana against oral bacteria was confirmed. The leaf and branch extracts (1 mg/disc) showed antibacterial activity against P. gingivalis only among several tested oral bacteria. The leaf extracts showed higher antibacterial activity, with values similar to those of chlorhexidine, which was used as a positive control. The MIC of the leaf extract against P. gingivalis was 0.4 mg/ml and showed bacteriostatic action. The inhibitory effects of the extract on biofilm formation and on gene expression related to biofilm formation by P. gingivalis were determined by biofilm biomass staining, scanning electron microscopy (SEM), and qRT-PCR analysis. The biofilm production rate and cell growth of P. gingivalis in the cultures treated with 0.2-2.0 mg/ml of S. koreana leaf extracts were significantly decreased in a concentration-dependent manner. The inhibitory effect on the formation of P. gingivalis biofilms at concentrations of 1 mg/ml was confirmed by SEM. The qRT-PCR analysis showed concentration-dependent suppression of the fimA and fimB gene expression associated with fimbriae formation in the cultures treated with 0.2-2.0 mg/ml S. koreana leaf extract. These results support the conclusion that S. koreana leaf extracts can be used as oral healthcare materials derived from natural materials, as demonstrated by the antibacterial action and inhibition of biofilm formation of P. gingivalis.

• Biomolecules & Therapeutics
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• v.21 no.3
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• pp.204-209
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• 2013

Osteoprotegerin (OPG) is a secreted glycoprotein and a member of the tumor necrosis factor receptor superfamily. It usually functions in bone remodeling, by inhibiting osteoclastogenesis through interaction with a receptor activator of the nuclear factor ${\kappa}B$ (RANKL). Transglutaminases-2 (Tgase-2) is a group of multifunctional enzymes that plays a role in cancer cell metastasis and bone formation. However, relationship between OPG and Tgase-2 is not studied. Therefore, we investigated the involvement of 12-O-Tetradecanoylphorbol 13-acetate in the expression of OPG in MG-63 osteosarcoma cells. Interleukin-$1{\beta}$ time-dependently induced OPG and Tgase-2 expression in cell lysates and media of the MG-63 cells by a Western blot. Additional 110 kda band was found in the media of MG-63 cells. 12-O-Tetradecanoylphorbol 13-acetate also induced OPG and Tgase-2 expression. However, an 110 kda band was not found in TPA-treated media of MG-63 cells. Cystamine, a Tgase-2 inhibitor, dose-dependently suppressed the expression of OPG in MG-63 cells. Gene silencing of Tgase-2 also significantly suppressed the expression of OPG in MG-63 cells. Next, we examined whether a band of 110 kda of OPG contains an isopeptide bond, an indication of Tgase-2 action, by monoclonal antibody specific for the isopeptide bond. However, we could not find the isopeptide bond at 110 kda but 77 kda, which is believed to be the band position of Tgase-2. This suggested that 110 kda is not the direct product of Tgase-2's action. All together, OPG and Tgase-2 is induced by IL-$1{\beta}$ or TPA in MG-63 cells and Tgase-2 is involved in OPG expression in MG-63 cells.

• Journal of Plant Biotechnology
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• v.44 no.1
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• pp.49-55
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• 2017

We investigated the callus induction and plant regeneration ability of 16 maize genotypes, including the Korean inbred lines, using 9 to 15 day-old immature zygotic embryos from maize grown in pots and from field cultures. Immature zygotic embryos placed on MS medium supplemented with L-proline 0.7 g/L, MES 0.5 g/L, Dicamba 1.5 mg/L, 2,4-D 0.5 mg/L, $AgNO_3$ 4 mg/L, and sucrose 20 g/L, showed the highest frequency of callus induction. The highest number of shoots regenerated when the embryogenic callus were transferred to MS medium supplemented with 5 mg/L zeatin. The root formation was observed when shoots were grown on MS medium supplemented with 0.2 mg/L indole-3-butyric acid (IBA). Additionally, under the same culture conditions, immature zygotic embryos from maize grown in the field also had a high frequency of plant regeneration. Except one genotype, 15 genotypes showed callus induction and shoot regeneration. Among the 16 genotypes tested, H99, B98, HW3, and B73 yielded the best plant regeneration. H99 showed maximum shoot formation from the primary embryogenic callus. The results suggest that genotypes and growth conditions of the maize plant plays very important roles for enhancing the embryogenesis competence of immature zygotic embryos. The successful regeneration from immature zygotic embryos of maize inbred lines provides a basis for molecular breeding of new cultivars by genetic transformation.

• Korean Journal of Plant Tissue Culture
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• v.22 no.1
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• pp.7-11
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• 1995

Protoplasts were isolated from hypocotyl tissues of 5-day-old Brassica oleracea var capitata Green Challenger seedlings. Several media were used for protoplast culture and shoot regeneration. The shoot-regeneration rapacity of protoplast derived callus depended on the initial culture medium. Protoplasts were cultured in liquid medium (B5 medium supplemented with CaCl2, 2H2O 600mg/L, g1ucose 20g/L, D-mannito1 70g/L, NAA lmg/L, BA lmg/L, 2.4-D 0.25 mg/L)at 27$^{\circ}C$ under the dark After 5 to 10 days, cultlues were diluted with medium with a reduced osmotic stabilizer and then transferred to illuminated conditions. The culture medium was changed with the fresh medium at 7- to 10-day-intervals until the formation of microcallus. Hypocotyl protoplast-derived callus proliferated when transferred to MS medium supplemented with NAA lmg/L, BA 1mg/L and GA$_3$ 0.02mg/L. Upon transfer to MS basal medium without growth regulators, roots were produced. In an attempt to increase the regeneration frequency, 10g/L polyvinylpyrrolidone was added to the regeneration medium, but the shoot regeneration was mot improved. The regenerated whole plants were acclimated in a sterized soilless mixture(vermiculite 2;perlite 2;peat moss1) in a culture room.

• Korean Journal of Materials Research
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• v.20 no.7
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• pp.370-373
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• 2010

In fabricating plasma display panels, the photolithographic process is used to form patterns of barrier ribs with high accuracy and high aspect ratio. It is important in the photolithographic process to control the refractive index of the photosensitive paste. The composition of this paste for photolithography is based on the $B_2O_3-SiO_2-Al_2O_3$ glass system, including additives of alkali oxides and rare earth oxides. In this work, we investigated the density, structure and refractive index of glasses based on the $B_2O_3-SiO_2-Al_2O_3$ system with the addition of $Li_2O$, $K_2O$, $Na_2O$, CaO, SrO, and MgO. The refractive index of the glasses containing K2O, Na2O and CaO was similar to that of the [BO3] fraction while that of the SrO, MgO and Li2O containing glasses were not correlated with the coordination fraction. The coordination number of the boron atoms was measured by MAS NMR. The refractive index increased with a decrease of molar volume due to the increase in the number of non-bridging oxygen atoms and the polarizability. The lowest refractive index (1.485) in this study was that of the $B_2O_3-SiO_2-Al_2O_3-K_2O$ glass system due to the larger ionic radius of $K^+$. Based on our results, it has been determined that the refractive index of the $B_2O_3-SiO_2-Al_2O_3$ system should be controlled by the addition of alkali oxides and alkali earth oxides for proper formation of the photosensitive paste.