• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.77-85
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• 2008

Grazing rates (GR) and pseudofaeces production (PFP) of native snail, Chinese mystery snail (Cipangopaludina chinensis malleata Reeve) on natural colonial morphs of Microcystis aeruginosa was measured. C. chinensis was collected from the upstream of the Geum River (Boryeong, Korea), where they co-habituated with Unio douglasiae and Lanceolaria acrorhyncha. The experiments were performed to evaluate the GR and PFP at different conditions such as; incubation time (1, 3, 5, 7, 9 and 11 hr), body size (3 to 6.1 cm, n=28), snail density (0.5, 1, 1.5 and 2.0 ind. $L^{-1}$) and prey concentration (168.3, 336.7, 505.0 and $673.0{\mu}g\;Chl-{\alpha}L^{-1}$). All experiments were triplicated, and conducted in transparent acrylic vessel (3L in volume). Regarding feeding time, a highest GR (0.538L $gAFDW^{-1}h^{-1}$) and PFP $(7.18mgAFDW^{-1})$ appeared at 1hr and 7hr after snail stocking, respectively. Interestingly, the snail, smaller than 4.5cm in body size, showed a wide range of GR ($-4.173{\sim}1.087L\;gAFDW^{-1}h^{-1}$) for the initial period (1 and 4hrs of stocking), compared to those greater than 4.5cm, which showed a stable FR, higher than 0.5L $gAFDW^{-1}h^{-1}$. Upon density effect, the density of 1.5 ind. $L^{-1}$ induced the most effective inhibition on Microcystis biomass with highest PFP. On the prey concentration, highest GR (0.897L $gAFDW^{-1}h^{-1}$) and PFP (3.67 mg $gAFDW^{-1}h^{-1}$) were induced at the level of $168.3{\mu}g\;Chl-{\alpha}L^{-1}$ and $673{\mu}g\;Chl-{\alpha}L^{-1}$, respectively. GR and PFP of this freshwater snail on the cyanobacterial bloom (M. aeruginosa) varied with the feeding conditions, and they were comparatively high for a short period of time less than 7hrs regardless of the stocking condition. Our results suggest that this freshwater snail has a potential to control cyanobacterial bloom when provided with suitable condition.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.155-166
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• 2007

We carried out a study on the marine environment, such as water temperature, salinity, density and chlorophyll ${\alpha}$, and the distribution of phytoplankton community, such as species composition, dominant species and standing crops in the Southwestern Sea of Korea during early summer 2005. According to the analysis of a T-S diagram, three characteristics of water masses were identified. We classified them into Korean and Chinese coastal water, the cold water and the oceanic water. The first was characterized by high temperature and low salinity in the surface layer influenced by river run offs from China and Korea, the second by low temperature and salinity in bottom layer originated from the bottom cold water of the Yellow Sea, and the third by high temperature and high salinity influenced by Tsushima warm currents. The internal discontinuous layer among them was formed at the intermediate depth (about $10{\sim}20\;m$ layer). And the thermal front appeared in the central parts between Tsushima warm currents and Korean and Chinese coastal waters in the Southwestern Sea of Korea. Chlorophyll ${\alpha}$ concentration was high values in the Korean coastal waters and sub-surface layers. But It was low concentration in the Tsushima warm currents regions. The $Chl-{\alpha}$ maximum layers appeared in the sub-surface layer below thermocline. The phytoplankton community in the surface and stratified layers was composed of a total of 40 species belonging to 26 genera. Dominant species were 2 diatoms, Paralia sulcata, Skeletonema costatum and a dinoflagellate, Scripsiella trochoidea. Standing crops of phytoplankton in the surface layer were very low with cell density ranging from 5 to $3.8\;{\times}\;10^3\;cells/L$. Diatoms were controlled by the expanded low salinity coastal waters of the low salinity with high concentrations of nutrients. Otherwise phytoflagellates were dominant in the high temperature regions where the Tsushima warm currents approches the Southwestern Sea of Korea in early summer.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.1-10
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• 2008

We patterned water quality of agricultural reservoirs according to the differences of six physico-chemical environmental factors (TN, TP, DO, BOD, COD, and SS) using four different ordination methods: Principal Components Analysis (PCA), Detrended Correspondence Analysis (DCA), Nonmetric Multidimensional Scaling (NMS), and Isometric Feature Mapping (Isomap). The data set was obtained from the water quality monitoring networks operated by the Ministry of Agriculture and Forestry and the Ministry of Environments. Chlorophyll-${\alpha}$ displayed the highest correlation with COD, followed by TP, BOD, SS, and TN (p<0.01), while negatively correlated with altitude and bank height of the reservoirs (p<0.01). Although four different ordination methods similarly patterned the reservoirs according to the gradient of nutrient concentration, PCA and NMS appeared to be the most efficient methods to pattern water quality of reservoirs based on the explanation power. Considering variable scores in the ordination map, the concentration of nutrients was positively correlated with Chl-${\alpha}$, while negatively correlated with altitude and bank height. These ordination methods may help to pattern agricultural reservoirs according to their water quality characteristics.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.224-232
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• 2000

Inorganic nutrient concentrations in relation to springtime physical parameters of the Yellow Sea were investigated during April 1996. Three major water masses, i.e., the Yellow Sea Warm Current Water (YSWC), Coastal Current Water (CCW) and Changjiang River Diluted Water (CRDW), prevailed in the study area. Water masses were vertically wel1 mixed throughout the study area, and nutrients were supplied adequately from bottom to surface layer. As result of ample nutrients supplied by vertical mixing together with progressed daylight condition, springtime phytoplankton blooms were observed, which was responsible for the depletion of inorganic nutrients in surface water column. Low nutrients concentration in bottom water of the central Yellow Sea (Stn. D9; nitrate: <2 ${\mu}$M, phosphate: <0.3 ${\mu}$) was associated with the entrance of YSWC which is characterized by high temperature and salinity. Influenced by runoff and vertical tidal mixing, CCW with high nutrient concentrations probably associated with China and Korea coastal waters with high nutrients concentration. For the local scale of inorganic nutrient distribution, nutrient transfers from coast to central areas were limited due to restriction imposed by tidal fronts (Stn. D6) and thus affected the horizontal nutrient profiles. Relatively high phytoplankton biomass was observed in the tidal front (Chl-${\alpha}$=12.38 ${\mu}$gL$^{-1}$) during the study period. Overall, the springtime nutrient distribution patterns in the Yellow Sea appeared to be affected by: (1) Large-scale influx of YSWC with low nutrient concentrations and CCW with high nutrient concentrations influenced by Korea and China coastal waters; (2) vertical mixing of water mass and phytoplankton distribution; and (3) local-scale tidal front as well as phytoplankton blooms alongthe tidal front.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.338-342
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• 2008

This study was performed to screen and select Lactobacillus strains from chicken feces for probiotic use in animals. Of these strains, strain AU had the highest immunostimulatory effect. Therefore, strain A12 was characterized as a potential probiotic. Strain A12 was tentatively identified as Lactobacillus acidophilus A12, using the API 50 CHL kit based on a 99.9% homology. L. acidophilus A12 was highly resistant to artificial gastric juice (pH 2.5) and bile acid (oxgall). Based on results from the API ZYM kit, leucine arylamidase, crystine arylamidase, acid phosphatase, naphthol-AS-BI-phosphohydrolase, ${\alpha}$-galactosidase, ${\beta}$-galactosidase, ${\alpha}$-glucosidase, ${\beta}$-glucosidase, and N-acetyl-${\beta}$-glucosamidase were produced by strain A12. L. acidophilus A12 showed resistance to several antibiotics (nisin, gentamicin, and erythromycin). The amount of interleukin $(IL)-1{\alpha}$ in $20{\times}$ concentrated supernatant from L. acidophilus A12 was approximately 156pg/ml. With regard to antioxidant activity, L. acidophilus A12 supernatant showed 60.6% DPPH radical scavenging activity. These results demonstrate the potential use of L. acidophilus A12 as health-promoting probiotics.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.255-264
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• 2017

To evaluate the water quality changes in agricultural reservoir covered with floating photovoltaic solar-tracking systems, the water quality variations with time and depth were monitored on both six sites for light blocking zones and four sites for light penetration zones after the installation of floating photovoltaic solar-tracking systems in Geumgwang reservoir at Anseong-si, Kyeonggi province. For one year with 16 monitoring events, water quality parameters [i.e., water temperature, pH, dissolved oxygen (DO), chlorophyll-a (Chl-a), and blue-green algae (BGA)] were monitored at depths of 0.3 m, 1 m, 3 m, and 5 m, while chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were monitored at depths of 0.3 m. Statistically, the difference in all water quality parameters was not significantly different (p > 0.05) at the level of significance of 0.05. Based on these results, the water quality data from light blocking zones (site 1~6) and light penetration zones (site 7~10) were clustered, and were compared with time and depth. As a result, the difference in water temperature, pH, DO, COD, TN, TP, Chl-a, and BGA between light blocking zones and light penetration zones was not significant (p > 0.05) with different time and depth. For Chl-a and BGA, some data from light blocking zones greater than light penetration zones were temporary observed due to the severe drought, low water storage rate, and over growth of periphyton. However, this temporal phenomenon did not impact the water quality. Considering the small water surface area (${\leq}0.5%$) covered by floating photovoltaic solar-tracking systems, the mixing effect of whole Geumgwang reservoir caused by Ekman current and continuous discharge were more dominant than the effect of reduced solar irradiance. Further study is warranted to monitor the changes in water quality and aquatic ecosystems with greater water surface area covered by floating photovoltaic solar-tracking systems for a long time.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1997.04a
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• pp.105-105
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• 1997

Reactive oxygen species(ROS)에 의한 세포독성이나 DNA손상은 노화와 암에 밀접한 관련이 있다. 본연구에서는 ROS중 hydroxyl radical 생성에 관여되는 $H_2O$$_2$에 의해 유도되는 산화적 세포독성이나 DNA손상에 억제적으로 작용할 수 있는 천연물을 창출하기 위한 연구를 하였다. 인삼(Panax Ginseng)C.A. Meyer의 석유에텔의 추출물(GPE)과 일부분획성분(P2)에 대하여 in vitro에서 지질과산화억제효과 및 프리라디칼소거효과를 시험하고 CHL Cell에서의 $H_2O$$_2$ 유도 세포독성과 산화적 DNA손상에 미치는 영향을 연구하였다. 한편 이들 물질을 기존의 항산화제인 ascorbic acid, dl-$\alpha$-tocopheorl 및 $\beta$-carotene등과 비교하였다.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.377-380
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• 2002

Wetland systems are widely accepted natural water purification systems around the world in nonpoint sources pollution control. In this study, the field experiment to reduce nonpoint source pollution loadings from agricultural drainage and polluted stream waters using wetland and pond system was performed. The removal rate of $BOD_5$, TSS, TN, TP, and $Chl-{\alpha}$ was 52%, 90%, 56%, 59%, and 81%, respectively. Performance of the experimental system was compared with existing data base (NADB), and it was within the range of general system performance. Overall the water quality improvement was apparent in wetland and pond system.

• Journal of the korean society of oceanography
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• v.31 no.1
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• pp.18-22
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• 1996

The effect of exogenous oxygen on hydrogen photoproduction was examined in the synchronously grown cells of marine Synechococcus sp. Miami BG 043511 under conditions of high cell density (0.6-0.8 mg chl-${\alpha}$ $ml^{-1}$) and high light intensity (1000 ${\mu}$E $m^{-2}$ $s^{-1}$). Hydrogen evolution after 20-h incubation did not decline under the initial oxygen concentrations up to 20%, but declined by half under 34% oxygen. 50% and 100% oxygen gas phase did not completely inhibit the hydrogen photoproduction during 40-h incubations. After 2-day pretreatment under 100% exogenous oxygen the hydrogen photoproduction capabilities were not irreversibly inhibited, which was demonstrated in the subsequent 9-day incubation under initial 0, 50 and even under 100% oxygen gas phase. This strain could be useful for developing a hydrogen photoproduction system under atmospheric oxygen concentration.

• BMB Reports
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• v.32 no.4
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• pp.363-369
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• 1999

The orf8(chlD) gene cloned from Streptomyces antibioticus T$\"{u}$99 was overexpressed using an E. coli system to confirm its biological function. Induction of the E. coli strain transformed with recombinant plasmid pRFJ 1031 containing orf8 resulted in the production of a 43,000 dalton protein. Glucose-1-phosphate thymidylyltransferase activity of the cell extract obtained from the transformed strain was 4-5 times higher than that of the control strain. The expressed protein was purified 18-fold from E. coli cell lysate using three chromatographic steps with a 17% overall recovery to near homogeneity. The N-terminal amino acid sequence of the purified protein agrees with the nucleotide sequence predicted from the orf8 gene. The SDS-PAGE estimated subunit mass of 43,000 dalton agrees well with that calculated from the amino acid composition deduced from the nucleotide sequence of the orf8 gene (43,000 Da). Also, the native enzyme has a monomeric structure with a molecular mass of 43,000 dalton. The purified protein showed glucose-1-phosphate thymidylyltransferase activity catalyzing a reversible bimolecular group transfer reaction, and was highly specific for dTTP and ${\alpha}$-D-glucose 1-phosphate as substrates in the forward reaction, and for dTDP-D-glucose and pyrophosphate in the reverse reaction.