• Korean Journal of Environmental Biology
• /
• v.22
• /
• pp.54-62
• /
• 2004

We examined the impacts of anthyopogenic pollutant (benzo〔a〕pyrene) on the growth and photosynthesis of five marine phytoplankton species (Skeletonema costatum, Heterosigma akashiwo, Prorocentrum dentatum, P. minimum, Aknshiwo sanguinea), which are dominant in Korean coastal water. After the 72 h exposure to benzo〔a〕pyrene, the dramatic decrease in cell numbers was observed in the range of 1 to 10 $\mu\textrm{g}$ L$^{-1}$ for S. costatum, P. minimum, P. dentatum, whereas for A. sanguinea and H. akashiwo at the low concentrations 0.1 to 1 $\mu\textrm{g}$ L$^{-1}$ . Among the 5 phytoplankton species, the highest growth inhibition concentration ($IC_{50}$/) was 6.20 $\mu\textrm{g}$ L$^{-1}$ for P. minimum, followed by 2.14 $\mu\textrm{g}$ L$^{-1}$ for P. dentatum, 1.68 $\mu\textrm{g}$ L$^{-1}$ for S. costatum, 0.74 $\mu\textrm{g}$ L$^{-1}$ for H. akashiwo, 0.10 $\mu\textrm{g}$ L$^{-1}$ for A. sanguinea. The five species exposed to the low concentration of 1 $\mu\textrm{g}$ L$^{-1}$ were recovered after transferring to new media, but the species exposed to the high concentrations of 10 and 100 $\mu\textrm{g}$ L$^{-1}$ were not recovered, with the exception of P. minimum. Those results indicate that the thecate dinoflagellate P. minimum is most tolerant to the chemical and the athecate dinoflagellate A. sanguinea is not. Geneyally, the cell-specific photosynthetic capacity of H. akashiwo exposed to the low concentrations of 0.1 and 1 $\mu\textrm{g}$ L$^{-1}$ was higher than that of the cells in the control, whereas the cells exposed to the high concentrations of 5 and 10 $\mu\textrm{g}$ L$^{-1}$ showed the negligible photosynthetic level by the first few days of the experiment. In the case of the cells exposed to the concentration of 5 $\mu\textrm{g}$ L$^{-1}$ , after 12 days of the experiment the photosynthetic capacity was increased toward the end of the experiment. This indicates that H. akashiwo may utilize the benzo〔a〕pyrene as a carton source for its growth when exposed to low concentrations. Results suggest that anthropogenic pollutants such as benzo〔a〕pyrene may have significant influence on the succession of phytoplankton species composition and the primary production in coastal marine environments.

• Journal of Life Science
• /
• v.19 no.11
• /
• pp.1529-1537
• /
• 2009

To elucidate further the antitumor effects of a natural L-arginine analogue, L-canavanine, the mechanism underlying apoptogenic activity of L-canavanine and its modulation by protein tyrosine kinase $p56^{lck}$ was investigated in human Jurkat T cells. When the cells were treated with 1.25 to 2.5 mM L-canavanine for 36 h, several apoptotic events including mitochondrial membrane potential (${\Delta\Psi}m$) loss, activation of caspase-9, -3, -8, and -7, poly (ADP-ribose) polymerase (PARP) degradation, and DNA fragmentation were induced without alteration in the levels of Fas or FasL. These apoptotic changes were more significant in $p56^{lck}$-deficient Jurkat clone JCaM1.6 than in $p56^{lck}$-positive Jurkat clone E6.1. The L-canavanine-induced apoptosis observed in $p56^{lck}$-deficient JCaM1.6 cells was significantly reduced by introducing $p56^{lck}$ gene into JCaM1.6 cells by stable transfection. Treatment of JCaM1.6/lck cells with L-canavanine caused a transient 1.6-fold increase in the kinase activity of $p56^{lck}$. Both FADD-positive wild-type Jurkat T cell clone A3 and FADD-deficient Jurkat T cell clone I2.1 exhibited a similar susceptibility to the cytotoxicity of L-canavanine, excluding involvement of Fas/FasL system in triggering L-canavanine-induced apoptosis. The L-canavanine-induced apoptotic sub-$G_1$ peak and activation of caspase-3, -8, and -7 were abrogated by pan-caspase inhibitor (z-VAD-fmk), whereas L-canavanine-induced activation of caspase-9 was not affected. These results demonstrated that L-canavanine caused apoptosis of Jurkat T cells via the loss of ${\Delta\Psi}m$, and the activation of caspase-9, -3, -8, and -7, leading to PARP degradation, and that the $p56^{lck}$ kinase attenuated the ${\Delta\Psi}m$ loss and activation of caspases, and thus contributed as a negative regulator to L-canavanine-induced apoptosis.

• Journal of Plant Biotechnology
• /
• v.32 no.4
• /
• pp.301-306
• /
• 2005

Conditions for efficient organogenesis and plant regeneration from Dianthus gratianopol suspension cultured cells were established. Shoot-forming calli of glossy surface, pale green and knobby type were selected from leaf explant-derived calli and were suspension-subcultured every week in CP liquid medium with 1.0 mg/L 2,4-D and 0.5 mg/L BAP. Combinations of 1.0 mg/L 2,4-D and 0.5 mg/L BAP, and 1.5 mg/L 2,4-D and 0.5 mg/L BAP were effective for the induction of regenerative callus from the suspension cultured cell clusters. Multiple shoot primordia were initiated from the green spots of these regenerative callus and formed shoots on MS medium with 1.0 mg/L TDZ and 0.5 mg/L PAA. Shoot regeneration frequency (calli regenerating at least one shoot) was about 87%. For plant regeneration, proliferated shoots were excised and transferred to MS medium with 0.1 mg/L NAA for root initiation after 9 weeks of culture. The regenerants were potted in soil and formed the flowering buds and petals. Also, adventitious shoots were formed from the excised green shoot primordia of regenerative callus and these shoots proliferated successfully and regenerated to whole plants.

• BMB Reports
• /
• v.32 no.5
• /
• pp.480-485
• /
• 1999

Tyrosine phenol-lyase of thermophilic Symbiobacterium sp. SC-1, which is obligately and symbiotically dependent on thermophilic Bacillus sp. SK-1, was purified and characterized. The enzyme is composed of four identical subunits and contains approximately 1 mol of pyridoxal 5'-phosphate (PLP) per mol subunit as a cofactor. The enzyme showed absorption maxima at 330 and 420 nm, and lost this absorption profile by treatment with phenylhydrazine. The apparent dissociation constsnt, $K'_D$, for PLP was determined with the apoenzyme to be about $1.2\;{\mu}M$. The isoelectric point was 4.9. The optimal temperature and pH for the $\alpha,\beta$-elimination of L-tyrosine were found to be $80^{\circ}C$ and pH 8.0, respectively. The substrate specificity of the enzyme was very broad: L-amino acids including L-tyrosine, 3,4-dihydroxyphenyl-L-alanine (L-DOPA), L-cysteine, L-serine, S-methyl-L-cysteine, $\beta$-chloro-L-alanine, and S-(o-nitrophenyl)-L-cysteine all served as substrates. D-Tyrosine and D-serine were also decomposed into pyruvic acid and ammonia at rates of 7% and 31% relative to their corresponding L-enantiomers, respectively. D-Alanine, which was inert as a substrate in a, $\beta$-elimination, was the only D-amino acid racemized by the enzyme. The $K_m$ values for L-tyrosine, L-DOPA, S-(o-nitrophenyl)-L-cysteine, $\beta$-chloro-L-alanine, and S-methyl-L-cysteine were 0.19, 9.9, 0.36, 12, and 5.5 mM, respectively.

• Journal of Plant Biotechnology
• /
• v.33 no.2
• /
• pp.99-104
• /
• 2006

This study was performed to investigate regeneration of plants differentiated from hybrid embryos between L. longifilorum Georgia and L. elegans Kakutanohikari. In addition, proliferation of callus and process of differentiation were investigated by histological observation. The germination of hybrid embryos was observed in 86 individuals from 48 slice cultures. Plant regeneration was effective on a medium supplemented with 1 mg/L HPh, and only callus proliferation was the highest in combination of 0.1 mg/L HPh and 1 mg/L BA. Also, plant regeneration was the most effective on a medium supplemented with 50 mg/L pyridoxine. We concluded that somatic embryos were formed from procambium of callus and proliferation of embryonic or proembryonic cells were stimulated with NAA from procambial cells.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.3 no.2
• /
• pp.93-102
• /
• 1970

1. On the basis of the samples collected on the eastern coast of Koje-Do from May to September, 1969, studies have been made on the growth and the relationships between the carapace length and the body length, and between the carapace length and the body weight of Penaeus japonicus Bate. 2. The mean carapace length of P. japonicus was 51mm in May, 57mm in June, 47mm in July and 50mm in September respectively. 3. As a result of the present studies two populations of P. japonicus exist in waters around Koje-Do, namely the spring and fall spawning populations. 4. The relationship between the carapace length ($\iota$) and the body length(L) and between the carapace length and the body weight (W) are indicated by the following equations: May $$L=2.6544{\iota}+3.1258$$ $$W=1.892{\iota}^{1.9844}$$ June $$L=2.8659{\iota}+2.1796$$ $$W=1.082{\iota}^{2.4323}$$ July $$L=2.5840{\iota}+3.3090$$ $$W=1.290{\iota}^{2.3094}$$ September $$L=2.4234{\iota}+4.5775$$ $$W=1.599{\iota}^{2.1857}$$ 5. With regard to the relationships between the carapace length and the body length and between the carapace length and the body weight there is no significant difference between the populations spawning in June and September. 6. The relationships between the carapace length ($\iota$) and the body length (L) and between the carapace length and the body weight (W) for the samples cultured at three different localities are indicated by the following equations: Koje-do $$L=3.7738{\iota}+0.0805\;(r=0.934)$$ $$W=0.4690{\iota}^{3.0713}$$ Oma-do $$L=2.993{\iota}+1.6455\;(r=0.990)$$ $$W=0.6328{\iota}^{2.6579}$$ Kumdang-do $$L=3.2749{\iota}+0.9055\;(r=0.983)$$ $$W=0.5768{\iota}^{2.8076}$$ 7. During the larval stages the relationship between the body length (L) and the rearing day (D) is indicated by the following equations: Zoeal stages (1-3) L=0.1279D+0.2686 (r=0.979) Mysis (1) - Post larva (6) L=0.1697D+0.5634 (r=0.994) Post-larvs (7) - Post larvs (21) L=0.1344D+1.9501 (r=0.978)

• Journal of the Korean Mathematical Society
• /
• v.35 no.4
• /
• pp.981-997
• /
• 1998

We shall show first general Metivier operators ${D_y}^2+(x^{2l}+y^{2k}){D_x}^2,l,k=1,2,....,have {G_{x,y}}^{{\theta,d}}$-hypoellipticity in the vicinity of the origin (0,0), where $\theta=\frac{l(1+k)}{l(1+k)-k},\;d=\frac{\theta+k}{1+k}$ (＞1), and finally the optimality of these exponents {$\theta$, d} will be shown.

• Communications of the Korean Mathematical Society
• /
• v.22 no.2
• /
• pp.209-218
• /
• 2007

In this paper we investigate the ${\ell}^p$ space structure of the Banach envelope of $WeakL_1$. In particular, the Banach envelope of $WeakL_1$ contains a complemented Banach sublattice that is isometrically isomorphic to the nonseparable Banach lattice ${\ell}^p$, ($1{\leq}p<\infty$) as well as the separable case.

• Korean Journal of Plant Resources
• /
• v.19 no.2
• /
• pp.315-322
• /
• 2006

This experiment was conducted to investigate the induction rate of callus and antioxidative activity of rosemary and lavender. Callus induction rate of rosemary was 92% and 94% at 0.5mg/L and 1.0mg/L of 2,4-D in the media, respectively. The antioxidative activities of rosemary appeared differently according to the callus cultured under various concentrations of plant growth regulators. The strongest effect was observed at 0.1mg/L of 2,4-D extract, with $43{\pm}1.5{\mu}g/mL$ of an RC50 value. Callus induction rate of lavender was 98% and 99% at 1.0mg/L of 2,4-D and 1.0mg/L of NAA in the media, respectively. The regeneration rate of roots lavender was 85% at 1.0mg/L of NAA in the media. Antioxidative activities of lavender appeared diffently according to the callus cultured under plant growth regulators. The strongest effect was observed in 0.1mg/L of 2,4-D extract, with $37.6{\pm}0.9{\mu}g/mL$ of an RC50 value, which could be compared with value of leaf.

• The Korean Journal of Applied Statistics
• /
• v.18 no.1
• /
• pp.43-56
• /
• 2005

In this study, a robust estimation method for the first-order autocorrelation coefficient in the time series model following AR(l) process with additive outlier(AO) is investigated. We propose the L-type trimmed least squares estimation method using the preliminary estimator (PE) suggested by Rupport and Carroll (1980) in multiple regression model. In addition, using Mallows' weight function in order to down-weight the outlier of X-axis, the bounded-influence PE (BIPE) estimator is obtained and the mean squared error (MSE) performance of various estimators for autocorrelation coefficient are compared using Monte Carlo experiments. From the results of Monte-Carlo study, the efficiency of BIPE(LAD) estimator using the generalized-LAD to preliminary estimator performs well relative to other estimators.