• 한국수산과학회지
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• 제32권3호
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• pp.359-367
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• 1999

적조 다발지역인 진동만에서 살조세균의 동태를 파악하기 위하여, 1998년 5월 19일부터 7월 7일까지, chlorophyll-a 및 살조세균의 계수$\cdot$분리하였고, 분리한 살조세균의 살조특성을 조사하였다. 본 연구기간동안 살조세균의 밀도는 $6.0\times10^1\~6.4\times10^5$cell $\ell^{-1}$의 범위에서 변동하였으며, chlorophyll-a의 농도의 증가 및 감소에 대하여 각각 1주일의 lag time을 두고 이와 동일한 변동양상을 나타내었다. 현장시료에서 분리된 3종의 살조세균 H519S5-4, H605S5-15 및 H605S5-22 균주의 살조범위를 침편모조류 Heterosigma akashiwo와 Chattonelia sp., 와편모조류 Gymnodinium catenatum, Gyrodinium impudicum 및 Cochlodinium polyklikoides, 규조류 Chaetoceros sp., Cescinodiscus granii, Ditylum brightwellii 및 Thalassiosira rotula를 대상으로 조사하였다. H60585-22 균주는 실험에 사용된 9종의 미세조류를 전부 사멸시켜 광범위한 살조범위를 나타내었다. 또한, 균주 H605S5-15는 H. akashiwo, G. catenatum, T. rotula 및 Chattonella sp.에 대하여, H519S5-4는 H. akashiwo, Chattonella sp., Chaetoceros sp. 및 G. catenatum에 대하여 살조력을 나타내었다. 살조유형은 3종 모두 세포 외 물질을 분비하여 살조하는 살조인자분비형 세균으로 나타났다. 세균이 나타내는 살조력은 식물성 플랑크톤의 군집동태에 영향을 미치는 중요한 요인이며, 연안에서 적조의 급격한 소멸에 관여하는 것으로 사료된다.

• 한국수산과학회지
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• 제34권6호
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• pp.605-610
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• 2001

이 연구에서는 해산어의 종묘 생산 과정에서 rotifer의 다음 단계 먹이생물로 이용되고 있는 Artemia의 대체 먹이생물로서 Diaphanosoma celebensis의 배양 환경 중 염분 농도가 미치는 영향을 검토하였다. 염분 농도 0 ppt에서 45ppt 사이에서 5 ppt 간격으로 염분 조정된 10단계의 조건하에서 D. celebensis의 증식 밀도, 안정배양 가능정도 (RPGI: Relative Population Growth Index) 그리고 먹이섭 이력 (RCN; Remaining Cell Numbers)을 비교 검토하였다. 그 결과, 염분 농도 0ppt에서 45ppt까지 10단계의 염분 배양 환경하에서 가장 높은 증식 밀도, 안정 배양도 (RPGI) 그리고 양호한 섭이력 (RCN)이 관찰된 실험구는 염분 농도 20ppt였으며, $15\~35ppt$의 염분 배양 환경하에서도 비교적 안정적인 배양 결과가 관찰되었고 20ppt를 중심으로 저염분 또는 고염분 배양 조건으로 갈수록 증식, RPGI 그리고 RCN은 저하되는 경향이 뚜렷하였다. 그리고 염분 농도 0ppt에서는 실험 개시 직후 전 개체가 사망하였다. 이 연구 결과 D. celebensis는 해산어의 종묘 생산 과정에서 Artemia의 대체 먹이생물로 광범위한 염분 농도 범위하에서 비교적 손쉽게 배양 가능할 것으로 판단되었다.

• The Plant Pathology Journal
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• 제30권3호
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• pp.288-298
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• 2014

We examined the efficacy of a bacterium for biocontrol of the root-knot nematode (RKN) Meloidogyne hapla in carrot (Daucus carota subsp. sativus) and tomato (Solanum lycopersicum). Among 542 bacterial isolates from various soils and plants, the highest nematode mortality was observed for treatments with isolate C1-7, which was identified as Bacillus cereus based on cultural and morphological characteristics, the Biolog program, and 16S rRNA sequencing analyses. The population density and the nematicidal activity of B. cereus C1-7 remained high until the end of culture in brain heart infusion broth, suggesting that it may have sustainable biocontrol potential. In pot experiments, the biocontrol efficacy of B. cereus C1-7 was high, showing complete inhibition of root gall or egg mass formation by RKN in carrot and tomato plants, and subsequently reducing RKN damage and suppressing nematode population growth, respectively. Light microscopy of RKN-infected carrot root tissues treated with C1-7 showed reduced formation of gall cells and fully developed giant cells, while extensive gall cells and fully mature giant cells with prominent cell wall ingrowths formed in the untreated control plants infected with RKNs. These histopathological characteristics may be the result of residual or systemic biocontrol activity of the bacterium, which may coincide with the biocontrol efficacies of nematodes in pots. These results suggest that B. cereus C1-7 can be used as a biocontrol agent for M. hapla.

• Ocean and Polar Research
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• 제34권1호
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• pp.65-71
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• 2012

Gambierdiscus toxicus, Adachi et. Fukuyo, is a benthic ciguatoxin-producing armored dinoflagellate, often attached to macroalgae. This organism is the primary causative agent of ciguatera fish poisoning which occurs in tropical and subtropical regions. However, regardless of the fact that the population of Gambierdiscus spp. has expanded to such temperate areas from sub-trophic and trophic areas, monitoring of G. toxicus has been lacking in the Korean coastal waters of temperate areas. This study was performed at the uninhabited Baekdo Islands off the southern coast of Korea and at Seopsom Island in the vicinity of Seogwipo, Jeju Province during April and May, 2011. Cell densities of Gambierdiscus spp. on macroalgae at Baekdo and Jeju Island ranged from zero to 56.4 cells $g^{-1}$. Maximum density was recorded on the brown alga Cladophora japonica at St. 3 of Jeju Island. In particular, the cell densities of Gambierdiscus spp. were influenced by the substrate characteristics of macroalgae. In the future, the continuous monitoring of toxic benthic dinoflagellate is necessary to predict and prevent ciguatera poisoning in Korean coastal waters.

• Journal of Microbiology and Biotechnology
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• 제16권11호
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• pp.1661-1677
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• 2006

Rhizobium and related genera are soil bacteria with great metabolic plasticity. These microorganisms survive in many different environments and are capable of eliciting the formation of nitrogen-fixing nodules on legumes. The successful establishment of symbiosis is precisely regulated and requires a series of signal exchanges between the two partners. Quorum sensing (QS) is a prevalent form of population density-dependent gene regulation. Recently, increasing evidence indicates that rhizobial quorum sensing provides a pervasive regulatory network, which plays a more generalized role in the physiological activity of free-living rhizobia, as well as during symbiosis. Several rhizobia utilize multiple, overlapping quorum sensing systems to regulate diverse properties, including conjugal transfer and copy number control of plasmids, exopolysaccharide biosynthesis, rhizosphere-related functions, and cell growth. Genomic and proteomic analyses have begun to reveal the wide range of functions under quorum-sensing control.

• 환경생물
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• 제18권1호
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• pp.95-104
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• 2000

In order to elucidate chatracteristics of water quality and seasonal dynamics of phytoplankton community in Kyungpo lake, the weekly variation of algal population and 11 environmental factors were investigated from March 1998 to February 1999. A total 121 species of phytoplankton belonged to 57 genera, 4 genera 7 species of the Euglenophyceae, 1 genera 2 species of the Chrysophyceae, 2 genera 3 species of the Cryptophyceae, 1 genera 1 species of the Dinophyceae, 6 genera 9 species of the Cyanophyceae, 28 genera 78 species of the Bacillario-phyceae and 15 genera 21 species of the Chlorophyceae, was identified. Cryptomonas sp., Chamydomonas sp., Nitzschia frustulum, Oscillatoria sp., Lyngbya sp, and Dictyosphaerium pulchellum occurred successively as dominant phytoplankton species from March 1998 to February 1999. Density of phytoplankton cell number showed the peak in early April when Chlamydomoas sp. was dominated. The diversity index of phytoplankton community showed low values in the dominating period of Cryptomonas sp. and Chlamydomonas sp. The concentration of chlorophyll a fluctuated between 1.09 and 107.7$\mu\textrm{g}$ㆍ1$^{-1}$. Water temperature, salinity, DO, conduc tivity and SS were ranged 0.5-27.8$^{\circ}C$, 2.8-25.2 ppt, 4.62-19.21 mgO$_2$ㆍ1$^{-1}$, 5.33-34.76 mS/cm and 0.017-0.184 mgㆍ1$^{-1}$, respectively. Annual means of Secchi disc transparency was 36cm and thai of pH value was 8.5. The concentrations of PO$_4$-P was ranged 0.0012-0.077 mgㆍ1$^{-1}$ , and showed high value from August to October. The concentrations of NO$_2$-N, NO$_3$-N and NH$_4$-N was ranged 0.0011-0.1 mgㆍ1$^{-1}$, 0.074-3.33mgㆍ1$^{-1}$ and 0.0024-0.259 mgㆍ1$^{-1}$, respectively. Among environmental factors, water temperature was negatively correlated with DO, salinity and conductivity, DO was positively correlated with salinity and conductivity. Chlorophyll a, one of the indicies of eutropication in lake, was negatively correlated with NH$_4$-N. The cell density of Cryptomonas sp., which was the most dominant species in this lake, was negatively correlated with transparency. [Kyoungpo lake, Phytoplankton, Cryptomonas sp. , Chlamydomonas sp., Seasonal variation].

• Journal of Ginseng Research
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• 제12권2호
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• pp.104-113
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• 1988

여러가지 농도의 cholesterol을 함유한 배지에서 배양한 CHO 세포내로 흡입된 cholesterol 양을 조사한 결과 흡입량이 배지의 cholesterol 농도에 비례하였으므로 cholesterol 흡입은 확산에 의한 것으로 생각된다. $^{125}I$으로 표지된 저밀도 지방단백질($^{125}I$-LDL)을 이용하여 여러가지 농도의 cholesterol을 함유한 배지에서 배양한 CHO 세포와 cholesterol이 없는 정상배지에서 배양한 CHO 세포에서의 LDL 수용체의 합성양상을 조사한 결과 배지에 가해준 cholesterol이 LDL 수용체 합성을 억제함을 확인하였다. Cholesterol의 LDL 수용체 생합성 억제작용에 미치는 ginsenoside의 영향을 조사하기 위해 ginsenoside와 cholesterol을 함께 함유한 배지에서 배양한 CHO 세포(시험군)과 cholesterol만을 포함한 배지에서 배양한 CHO 세포(대조군)에서의 LDL 수용체의 활성양상을 분석한 결과 대조군에 비해 시험군에서의 LDL 수용체 활성이 크게 증가하였다. RNA 및 단백질 합성도 시험군이 대조군보다 증가하였음을 관찰하였다. 그러나 이와 같은 실험조건하에서의 대조군과 시험군의 cholesterol농도를 측정한 결과 시험군의 cholesterol 농도가 대조군보다 훨씬 저하되고 있었다. Ginsenoside의 cholesterol농도 저하작용을 관찰하기 위해 CHO세포에서의 cholesterol의 steroid hormone(estradiol, progesterone)으로의 전환에 미치는 ginsenoside의 영향을 조사한 결과 ginsenoside는 cholesterol의 hormone으로의 전환을 촉진하였음이 확인되었다. 위와 같은 실험결과로 볼 때 ginsenoside는 CHO 세포내부에서의 cholesterol의 LDL 수용체 합성억제를 완화시켜 주는 것이라고 생각된다.

• Fisheries and Aquatic Sciences
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• 제3권1호
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• pp.26-32
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• 2000

Monospecific red tide by a toxic dinoflagellate belonging to the genus Alexandrium occurred at Chindong Bay in the southern coast of Korea and continued from April 6th to 15th in 1997. The ratio of its cell number to total phytoplankton cell number was much higher than $95\%$. This organism was identified as Alexandrium tamarense, although slight morphological differences were found comparing to the original and successive descriptions of the species. We found neither anterior nor posterior attachment pores in these cells of the bloom population. The occurrence of red tide caused by A. tamarense was first reported in Korea. Its plate formula is Po, Pc, 4', 6"c, 8s, 5"' and 2"". Thecal plates are thin with pore-like ornamentation. In those plates, the anterior part of the first apical plate (1') is narrower and its posterior end has sometimes a block-like accessory, but this variation was considered within the range of the morphological variability of this taxon. The cell density during the red tide exhibited a wide range of variation by the depth of water column, ranging from $2\times10^6$ cells$l^{-1}$ to $5\times10^6$ cells·$l^{-1}$. Water temperature varied from 11.8 to $12.3^{\circ}C$. Toxicity of A. tamarense during red tide was measured as $8.8\times10^5$. $MU\;\cdot\;cell^{-1}$ by mouse bioassay.

• Nutrition Research and Practice
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• 제2권4호
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• pp.289-294
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• 2008

Pre-B-cell leukemia transcription factor 1 (PBX1), which is located on chromosome 1q23, was recently reported to be associated with type 2 diabetes mellitus. We examined whether single nucleotide polymorphisms (SNPs) of the PBX1 gene are associated with overweight/obesity in a Korean population. We genotyped 66 SNPs in the PBX1 gene and investigated their association with clinical phenotypes found in 214 overweight/obese subjects and 160 control subjects using the Affymetrix Targeted Genotyping chip array. Seven SNPs (g.+75l86C>T, g.+78350C>A, g.+80646C>T, g.+138004C>T, g.+185219G>A, g.+191272A>C, and g.+265317T>A) were associated with the risk of obesity in three models (codominant, dominant, and recessive) (P=0.007-0.05). Haplotype 1 (CAC) and 3 (TAC) of block 3 and haplotype 2 (GGAAT) of block 10 were also strongly associated with the risk of obesity. In the control group, subjects that had homozygote for the major allele for both g.+185219G>A and g.+191272A>C showed lower high density lipoprotein-cholesterol (HDL-C) level compared to those possessing the minor allele, suggesting that the association between the homozygote for the major allele for both g.+185219G>A and g.+191272A>C and HDL-C is attributable to the increased risk of obesity. This study suggests that the PBX1 gene is a possible risk factor in overweight/obese patients.

• 한국환경과학회지
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• 제19권8호
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• pp.951-960
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• 2010

Sediment works as a resource for electric cells. This paper was designed in order to verify how sediment cells work with anodic material such as metal and carbon fiber. As known quite well, sediment under sea, rivers or streams provides a furbished environment for generating electrons via some electron transfer mechanism within specific microbial population or corrosive oxidation on the metal surfaces in the presence of oxygen or water molecules. We experimented with one type of sediment cell using different anodic material so as to attain prolonged, maximum electric power. Iron, Zinc, aluminum, copper, zinc/copper, and graphite felt were tested for anodes. Also, combined type of anodes-metal embedded in the graphite fiber matrix-was experimented for better performances. The results show that the combined type of anodes exhibited sustainable electricity production for ca. 600 h with max. $0.57\;W/m^2$ Al/Graphite. Meanwhile, graphite-only electrodes produced max. $0.11\;W/m^2$ along with quite stationary electric output, and for a zinc electrode, in which the electricity generated was not stable with time, therefore resulting in relatively sharp drop in that after 100 h or so, the maximum power density was $0.64\;W/m^2$. It was observed that the corrosive reaction rates in the metal electrodes might be varied, so that strength and stability in the electric performances(voltage and current density) could be affected by them. In addition to that, COD(chemical oxygen demand) of the sediment of the cell system was reduced by 17.5~36.7% in 600 h, which implied that the organic matter in the sediment would be partially converted into non-COD substances, that is, would suggest a way for decontamination of the aged, anaerobic sediment as well. The pH reduction for all electrodes could be a sign of organic acid production due to complicated chemical changes in the sediment.