• Korean journal of applied entomology
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• v.34 no.3
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• pp.266-277
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• 1995

The adult brown planthopper possesses tow oval shaped compound eyes which, on their ventral borders, curve around the base of the antennae. Compound eye of the adult brown planthopper is recognised apposition eye which each ommatidium is optically isolated from it surroundings, the rhabdoms receiving light only from their own corneal lens. Each ommatidium possesses its own dioptric apparatus formed from the cuticular cornea and an underlying crystalline cone. The retinula cells lying immediately beneath the crystalline cone have their individual rhabdomeres tightly opposed to form one central, closed rhbdom. The rhabdom stretches from the spex of the crystalline cone nearly to the basement membrane and is approximately 110~120 $\mu\textrm{m}$ in length. The crystalline cone is surrounded by a pair of primary pigment cells an these in turn are surrounded by accessory pigment cells. Accessory pigment cells extend beyond the crystalline cone surrounding the retinular cells in the distal region of the eye. The crystalline cone is surrounded by the distal-most regions of the retinula cells show the presence of seven cells and sections taken proximally in the last quarter of the omatidium before the basement membrane is reached, reveal the presence of a small, eighth retinula cell which also contributes to the central rhabdom. Each ommatidium has a central rhabdom formed from the modified inner border of all of the retinula cells. Th rhabdom consists of micrvilli arising from the inner wall of each retinula cell. In cross section th microvilli exhibit a characteristic honeycomb appearance. Pigment cells comprise the primary pigment cells enveloping the crystalline cone, the accessory pigment cells extending from the inner surface of the comea to the basement membrane and the small pigment cells of the basement membrane.

• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.194-202
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• 2003

To isolate alga-lytic bacteria, a number of samples were collected from Lake of Sukchon and Pal'tang reservoir where cyanobacteria blooming occurred. HY0210-AK1, which exhibited high alga-lytic activity, was isolated using Anabaena cylindrica lawn. The morphological and biochemical characteristics of the isolate HY0210-AK1 were very similar to that of the genus Rhizobium. Taxonomic identification including 16S rDNA base sequencing and phylogenetic analysis indicated that the isolate Hy0210-AK1 had a 99.1% homology in its 16S rDNA babe sequence with Sphingobium herbicidovorans. A. cylindrica NIES-19 was susceptible to the alga-lytic bacterial attack. The growth-inhibiting offset of the bacterium was not different on A. cylindrica NIES-19 when Sphingobium herbicidovorans HY0210-AK1 was in the lag, exponential, and stationary growth phase, although the alga-Iytic effect of S. herbici-dovorans HY0210-AK1 that in stationary growth phase was somewhat pronounced at the first time of inoculation. When S. herbicidovorans HY0210-AK1 was inoculated was inoculated with $1\times 10^{8}$ CFU $ml^{-1}$ together with A cylindrica NIES-19, the bacterium proliferated and caused algal lysis. A. cylindrica NIES-19 died when S. herbicidovorans HY0210 AKl was added to the algal culture but not when duly the filtrates from the bacterial culture was added. This suggests that extracellular substances are not responsible for inhibition of A. cylindrica NIES-19 and that algal Iysis largely attributed to direct interaction between S. herbicidovorans HY0210-AK1 and A. cylindrica NIES-19. The alga-lytic bacterium HY0210-AK1 caused cell lysis and death of three strain of Micro-cystis aeruginosa, but revealed no alga-Iytic effects on the Stephanodiscus hantzschii.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.58-64
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• 2007

Overwintering adults of sycamore lace bug (Corythucha ciliata) infected by an unidentified pathogenic fungus were found on the stems of street trees of sycamore in Cheongju city. The objective of this study was to describe this entomopathogenic fungus infecting overwintering sycamore lace bug adults. This unidentified fungus colonized the insect adult body and formed white colony with subglobose clusters of conidiocarps. The size of conidiocarps was 300 to $400{\mu}m$ and each conidium was 15 to $20{\mu}m$. The conidiospore was globus and 2.5 to $3.0{\mu}m$ in diameter, and the hyphae were 1 to $5{\mu}m$ thick. This fungus was successfully isolated and cultivated on potato dextrose agar medium (PDA). The fungal colony was white and then became light yellow. When conidia from this pure culture were inoculated into the overwintering adults, the fungus formed conidiocarps with the same morphology on the insect body and the lethal rate by the fungus was $88{\pm}16%$. This fungus has over 99% homology with Cordyceps bassiana (imperfect fungal name is Beauveria bassiana) in ITS-5.8s rDNA base sequence. The fungal ecology and the infection process of the fungus into its host need to be clarified before using this fungus as a biological control agent.

• Korean System Dynamics Review
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• v.2 no.2
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• pp.25-40
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• 2001

This paper describes the forecast of power plant construction in a competitive korean electricity market. In Korea, KEPCO (Korea Electric Power Corporation, fully controlled by government) was responsible for from the production of the electricity to the sale of electricity to customer. However, the generation part is separated from KEPCO and six generation companies were established for whole sale competition from April 1st, 2001. The generation companies consist of five fossil power companies and one nuclear power company in Korea at present time. Fossil power companies are scheduled to be sold to private companies including foreign investors. Nuclear power company is owned and controlled by government. The competition in generation market will start from 2003. ISO (Independence System Operator will purchase the electricity from the power exchange market. The market price is determined by the SMP(System Marginal Price) which is decided by the balance between demand and supply of electricity in power exchange market. Under this uncertain circumstance, the energy policy planners such as government are interested to the construction of the power plant in the future. These interests are accelerated due to the recent shortage of electricity supply in California. In the competitive market, investors are no longer interested in the investment for the capital intensive, long lead time generating technologies such as nuclear and coal plants. Large unclear and coal plants were no longer the top choices. Instead, investors in the competitive market are interested in smaller, more efficient, cheaper, cleaner technologies such as CCGT(Combined Cycle Gas Turbine). Electricity is treated as commodity in the competitive market. The investors behavior in the commodity market shows that the new investment decision is made when the market price exceeds the sum of capital cost and variable cost of the new facility and the existing facility utilization depends on the marginal cost of the facility. This investors behavior can be applied to the new investments for the power plant. Under these postulations, there is the potential for power plant construction to appear in waves causing alternating periods of over and under supply of electricity like commodity production or real estate production. A computer model was developed to sturdy the possibility that construction will appear in waves of boom and bust in Korean electricity market. This model was constructed using System Dynamics method pioneered by Forrester(MIT, 1961) and explained in recent text by Sternman (Business Dynamics, MIT, 2000) and the recent work by Andrew Ford(Energy Policy, 1999). This model was designed based on the Energy Policy results(Ford, 1999) with parameters for loads and resources in Korea. This Korea Market Model was developed and tested in a small scale project to demonstrate the usefulness of the System Dynamics approach. Korea electricity market is isolated and not allowed to import electricity from outsides. In this model, the base load such as unclear and large coal power plant are assumed to be user specified investment and only CCGT is selected for new investment by investors in the market. This model may be used to learn if government investment in new unclear plants could compensate for the unstable actions of private developers. This model can be used to test the policy focused on the role of unclear investments over time. This model also can be used to test whether the future power plant construction can meet the government targets for the mix of generating resources and to test whether to maintain stable price in the spot market.

• Journal of Life Science
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• v.30 no.2
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• pp.122-128
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• 2020

Although Candida albicans is the major fungal pathogen of candidemia, severe infections by non-albicans Candida (NAC) spp. have been increasing in recent years. Among NAC spp., C. glabrata has emerged as the second most common pathogen. However, few studies have been conducted to investigate its structure, epidemiology, and basic biology. In the present study, multi-locus sequence typing (MLST) was performed with a total of 102 C. glabrata clinical isolates that were isolated from various types of clinical specimen. For MLST, six housekeeping genes-FKS, LEU2, NMT1, TRP1, UGP1, and URA3-were amplified and sequenced. The results were analyzed using the C. glabrata database. Out of a total of 3,345 base-pair DNA sequences, 49 variable nucleotide sites were found, and the results showed that 12 different sequence types (ST) were identified from the 102 clinical isolates. The data also demonstrated that the undetermined ST1 was the most predominant ST in Korea. Further, seven undetermined STs (UST) containing UST2-8 were classified at specific loci. The data from this study may provide a fundamental database for further studies on C. glabrata, including its epidemiology and evolution. The data may also contribute to the development of novel antifungal agents and diagnostic tests.

• Journal of Life Science
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• v.25 no.5
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• pp.507-514
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• 2015

D-Xylulose is phosphorylated to D-xylulose-5-phosphate by D-xylulose kinase before it enters glycolysis via the nonoxidative pentose phosphate pathway. A gene encoding a novel D-xylulose kinase (XK) from K. gwangalliensis strain SJ2 was sequenced and expressed in E. coli. The sequence of the isolated XK gene was 1,419 bp, encoding 472 amino acids. The XK protein was more closely related to the Arthrobacter phenanthrenivorans XK than to the Bifidobacterium catenulatum one, as reflected in the sequence identity (54.9% vs. 38.7%). The XK gene was subcloned into the pCold-II expression vector. The resulting plasmid was transformed into E. coli strain BL21 (DE3) cells and the expression of the recombinant XK protein was induced by the addition of IPTG. The resulting protein was expressed as a fusion protein of approximately 48 kDa containing a N-terminal six-histidine extension that was derived from the expression vector. The expressed protein was homogenized by affinity chromatography and showed enzymatic activity corresponding to D-xylulose kinase. XK enzyme kinetic studies with D-xylulose and ATP showed a Km of 250±20 μM and 1,300±50 μM, respectively. The results obtained from this study will provide a wider knowledge base for the characterization of D-xylulose kinase at the molecular level.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.790-799
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• 1997

The purpose of this study is to investigate the effects of yeast addition as starter on kimchi fermentation. The strains used as starter were Saccharomyces sp. YK-17 and Saccharomyces fermentati YK-19 isolated from kimchi, grew under anaerobic condition and low temperature, which showed the acid and base resistances. Chemical and microfloral changes, as well as the sensory properties of starter added kimchi during fermentation were compared with the control fermented without starter. The acidity of kimchi juice was lower and pH was higher in starter added kimchi than the control. Particularly addition of S. fermentati YK-19 prolonged the optimally fermented period (pH 4.0, acidity $0.6{\sim}0.8%$) up to more than 63%. The content of lactic acid, the major non-volatile organic acid in kimchi, was increased rapidly followed by S. sp. YK-17 and S. fermentati YK-19 group. The microfloral changes were found a little different among the samples. Among the microorganisms, Leuconostoc sp. and Lactobacillus sp. showed highest change, and Streptococcus sp. and Pediococcus sp. showed ralatively low change. The growth of Lactobacillus sp. which was the main acidifing microorganism was inhibited by starter addition, particularly by S. fermentati YK-19. The sensory characteristics of acidic and moldy flavor were significantly reduced by the addition, while fresh flavor was increased in starter added group.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1157-1163
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• 1996

Bangah, one of the herbs grown in Korea, was investigated for its antioxidant activity. The ether extracts of bangah herb was separated into neutral, phenolic, acidic and basic fractions and further separated into subfractions. Antioxidative activities were measured by hydrogen donating activity (HDA), peroxide value (POV), thiobarbituric acid (TBA) value and inhibition activity against lipid peroxidation of rat liver microsomes, The subfraction components were identified by GC/MS and NMR. Phenolic, though being very small in quantity, showed higher antioxidant activity at all assay system by hydrogen donating activity. POV, TBA value and inhibition activity against lipid peroxidation of rat liver microsomes. Five subfractions(P-1, P-2, P-3, P-4 and P-5) were fractionated from phenolic fraction of bangah herbs, and subfraction P-2 among them showed strong antioxidant activity on a level with BHT or gallic acid at each assay system. Four compounds (peak I, peak II, peak III and peak IV) were isolated by gas chromatogram of TMS derivatives of subfraction P-2 and thes compounds were confirmed to be phenolic substance having -OH and COOH group. There subfractions (N-1, N-2 and N-3) were fractionated from neutral fraction of bangah herbs, and subfraction N-2 among them showed highest antioxidant activity and inhibition activity against lipid peroxidation of rat liver microsomes. Subfraction N-2 was indentified to be estragole by H-NMR spectroscopy.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.917-923
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• 2002

Inhibitory mechanism of the anticoagulant polysaccharide purified from Codium fragile was investigated. The anticoagulant compounds (Cf-30-IV-4-ii, CF-30-IV) prolonged the clotting time at both activated partial thrombo-plastin time (aPTT) and thrombin time (TT). The Inhibition factor assay of instrinsic coagulation pathway in the blood showed that the anticoagulant polysaccharide (CF-30-IV-4-ii) inhibited other factors such as Ⅷ, Ⅸ, Ⅵ and Ⅷ of the coagulation cascade, which did not affect the lupus anticoagulant AB activity. In the thrombin inhibition pattern the CF-30-IV-4-ii did not directly influence the fibrine formation mediated by thrombin but af-fected the anticoagulant activity through the activation of antithrombin III. Base on these result, the anticoaglant polysaccharide (CF-30-IV-4-ii) was considered to inhibit serine pretense involved in the blood coagulation cascade through the enhancing antithrombin III activity. The residual effects of anticoagulant activity and antithrombosis were tested with ICR mice. The anticoagulant polysaccharide (CF-30-W) kept its anticoagulant activitv for 6 hrs with 100% survival at a dose of 150 mg/kg in the antithromboisis test. The anticoagulant effect of CF-30-RF in ex vivo was proportional to the concentration of intravenously injected dose up to 100 mg/kg.

• Journal of Environmental Health Sciences
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• v.28 no.1
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• pp.21-29
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• 2002

To identify and evaluate the dichlorobenzidine(DCB)-DNA adducts in liver cell and bladder epithelial cells by $^{32}$ P-postlabeling and GC/MS-SIM, we orally exposed the dichlorobenzidine(20mg/kh body wt./day) to male Sprague-Dawley rats(l85$\pm$10g) for 14 days. Two kinds of DCB-DNA adduct(A1 and A2) were found at the same site of thin layer chromatogram of $^{32}$ P-postlabeling method in liver cells and bladder epithelial cells. In liver cells, relative adduct labeling(RAL) $\times$ 10$^{12}$ of DCB-DNA adduct A1 were 34.1$\pm$3.71 and 69.9$\pm$5.02, that of adduct A2 were 74.1$\pm$10.1 and 105.1$\pm$10.1 on 10 and 14 days after treatment, respectively. And in bladder epithelia cells, RAL $\times$ 10$^{12}$ of DCB-DNA adduct A1 were 5.92$\pm$1.60 and 15.9$\pm$1.31, that of adduct A2 were 9.81$\pm$2.81 and 22.8$\pm$1.79 on 10 and 14 days after treatment, respectively. DCB metabolites formed DNA adducts were monoacetyl-dichlorobenzidine(acDCB) and diacetyl-dichlorobenzidine(di-acDCB), which was identify by gas chromatography/mass spectrometry-scan ionization mode(GC/MS-SIM), after hydrolysis of DCB-DNA adducts isolated from live cells and bladder epithelial cells. The base peak of acDCB were 252 and 294 m/z, and that of di-acDCB were 252, 294 and 336 m/z. In conclusion, the exposed DCB formed two kinds of DCB-DNA adduct, the proximate materials of that were acDCB and di-acDCB in liver and bladder epithelial cells. And the above GC/MS-SIM method was found the DCB-DNA adducts could be monitoring by gas chromatography.