• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.417-433
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• 2011

The study tested QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation and HPLC-MS/ MS analysis for measurement of pesticide residues in fruit and vegetable. 240 kinds of pesticides spiked at three levels of 90, 45, 9 ng/g in lettuce and apple. For QuEChERS sample preparation, graphitized carbon black (GCB) was used for only lettuce in dispersive-SPE as absorbent. Matrix-matched standard calibration was used for quantitative analysis of HPLC-MS/MS. 218 pesticides (91%) in apple and 207 pesticides (86%) in lettuce showed recoveries in the range of 70~120% with $RSD{\leq}20%$. The lowest calibrated level (LCL) were 4.5 ng/g for 192 pesticides, 9 ng/g for 42 pesticides, 45 ng/g for 3 pesticides and 3 pesticides were not detected at all concentration levels. The results showed that the QuEChERS sample preparation and HPLC-MS/MS analysis can be applied to multi-residue analysis of pesticides in vegetables and fruits.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.148-155
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• 2014

The transfer pattern of chlorpyrifos present in soil to cucumber plants were assessed and reported with plant growth, concentration dependency, and duration. Cucumber seedlings cultivated in a growth chamber for 30 days and a greenhouse for 120 days. Weight and length of cucumbers cultivated in the chamber increased with the increasing time, while the uptake of chlorpyrifos by cucumber increased a period from 0 to 15 days and decreased after 15 days. Uptake rates of chlorpyrifos into a cucumber plant were 1.0~1.3% to initial amounts treated with 20 and 40 mg/kg to soil. Most chlorpyrifos residues were detected in root, followed by stem and leaf. Results of the greenhouse test showed that chlorpyrifos amounts in cucumber fruits were present less than LOQ (0.02 mg/kg), and chlorpyrifos was mainly found in the root of the cucumber plant. Chlorpyrifos absorbed in a cucumber under greenhouse condition was smaller than that in chamber condition as 0.03~0.04%. Degradation patterns of chlorpyrifos in soils were similar during indoor and outdoor tests with half-lives of 25.8~73.0 days. These results may be useful for establishing the management strategy of residual pesticides in soil environment.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.537-546
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• 2015

Classical swine fever (CSF) is a highly contagious disease of pigs caused by CSF virus (CSFV). E2 is the major viral envelope protein of immune dominance that induces neutralizing antibodies and confers protection against CSFV infection. The B/C domains of E2 are variable among CSFV isolates, which could affect immunogenicity and binding to antibodies. We attempted to characterize the epitope recognized by a monoclonal antibody 2B6 (mAb-2B6) raised against the E2 B/C domains of the vaccine C-strain and to examine if mutations in the epitope region would affect antibody binding and viral neutralization. The epitope specific for mAb-2B6 recognition is linear, spanning five residues ⁷⁷⁴DGXNP⁷⁷⁸ in the B/C domains. The residue N777 is indispensable for the specificity. The epitope exists only in group 1 strains, but not in those of group 2. The recombinant viruses containing individual mutations on the epitope region lost the reactivity to mAb-2B6. The mutant virus RecC-N777S had low replication potential, about 10-fold decrease in the yield of progeny virus particles, whereas the mutant virus RecC-P778A reverted to proline upon continuous passaging. The mutations on the mAb-2B6 epitope region did not affect neutralization by anti-C-strain polyclonal sera from pigs. Deletion from aa774 covering the mAb-2B6 epitope, but not that from aa781, also affected binding with the polyclonal antibodies from vaccinated pigs, although the major binding region for the vaccinated antibodies is aa690-773.

• Journal of Microbiology and Biotechnology
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• v.23 no.4
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• pp.499-510
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• 2013

Among 25 isolates, Aspergillus fumigatus ASH (JX006238) was identified as a potent producer of homocysteine ${\gamma}$-lyase. The nutritional requirements to maximize the enzyme yield were optimized under submerged (SF) and solid-state fermentation (SSF) conditions, resulting in a 5.2- and 2.3-fold increase, respectively, after the last purification step. The enzyme exhibited a single homogenous band of 50 kDa on SDS-PAGE, along with an optimum pH of 7.8 and pH stability range of 6.5 to 7.8. It also showed a pI of 5.0, as detected by pH precipitation with no glycosyl residues. The highest enzyme activity was obtained at $37-40^{\circ}C$, with a $T_m$ value of $70.1^{\circ}C$. The enzyme showed clear catalytic and thermal stability below $40^{\circ}C$, with $T_{1/2}$ values of 18.1, 9.9, 5.9, 3.3, and 1.9 h at $30^{\circ}C$, $35^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$, and $60^{\circ}C$, respectively. Additionally, the enzyme $K_r$ values were 0.002, 0.054, 0.097, 0.184, and 0.341 $S^{-1}$ at $30^{\circ}C$, $35^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$, and $60^{\circ}C$, respectively. The enzyme displayed a strong affinity to homocysteine, followed by methionine and cysteine when compared with non-S amino acids, confirming its potency against homocysteinuria-related diseases, and as an anti-cardiovascular agent and a specific biosensor for homocysteinuria. The enzyme showed its maximum affinity for homocysteine ($K_m$ 2.46 mM, $K_{cat}\;1.39{\times}10^{-3}\;s^{-1}$), methionine ($K_m$ 4.1 mM, $K_{cat}\;0.97{\times}10^{-3}\;s^{-1}$), and cysteine ($K_m$ 4.9 m M, $K_{cat}\;0.77{\times}10^{-3}\;s^{-1}$). The enzyme was also strongly inhibited by hydroxylamine and DDT, confirming its pyridoxal 5'-phosphate (PLP) identity, yet not inhibited by EDTA. In vivo, using Swiss Albino mice, the enzyme showed no detectable negative effects on platelet aggregation, the RBC number, aspartate aminotransferase, alanine aminotransferase, or creatinine titer when compared with negative controls.

• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.997-1006
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• 2018

As shown during the 2009 pandemic H1N1 (A(H1N1)pdm09) outbreak, egg-based influenza vaccine production technology is insufficient to meet global demands during an influenza pandemic. Therefore, there is a need to adapt cell culture-derived vaccine technology using suspended cell lines for more rapid and larger-scale vaccine production. In this study, we attempted to generate a high-growth influenza vaccine strain in MDCK cells using an A/Puerto/8/1934 (H1N1) vaccine seed strain. Following 48 serial passages with four rounds of virus plaque purification in MDCK cells, we were able to select several MDCK-adapted plaques that could grow over $10^8PFU/ml$. Genetic characterization revealed that these viruses mainly had amino acid substitutions in internal genes and exhibited higher polymerase activities. By using a series of Rg viruses, we demonstrated the essential residues of each gene and identified a set of high-growth strains in MDCK cells ($PB1_{D153N}$, $M1_{A137T}$, and $NS1_{N176S}$). In addition, we confirmed that in the context of the high-growth A/PR/8/34 backbone, A/California/7/2009 (H1N1), A/Perth/16/2009 (H3N2), and A/environment/Korea/deltaW150/2006 (H5N1) also showed significantly enhanced growth properties (more than $10^7PFU/ml$) in both attached- and suspended-MDCK cells compared with each representative virus and the original PR8 vaccine strain. Taken together, this study demonstrates the feasibility of a cell culture-derived approach to produce seed viruses for influenza vaccines that are cheap and can be grown promptly and vigorously as a substitute for egg-based vaccines. Thus, our results suggest that MDCK cell-based vaccine production is a feasible option for producing large-scale vaccines in case of pandemic outbreaks.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.577-583
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• 2011

In 2007, pet food contaminated with melamine caused hundreds of dogs and cats to develop renal failure all over the world. In 2008, over 294,000 infants consumed infant formula and developed kidney stones in China. Further investigation revealed that fish feed also contained melamine; this raised concerns about melamine residues in edible fish tissues, which could have caused the urinary tract stone epidemic. In Korea, catfish fed with assorted feed that included cuttlefish organs that contained melamine developed whitening syndrome and fell dead in some populations in 2008. This event raised suspicions about the toxicity of melamine and all feeds containing melamine were immediately recalled. In this study, we investigated the rates of melamine accumulation and depletion in muscle and viscera of catfish to propose proper withdrawal periods. One group of catfish was fed a commercially available diet that contained 30, 100 and 300 mg melamine per kg diet for 14 days. To investigate residual melamine contents in muscle and viscera, other experimental groups were fed a melamine free diet after being fed melamine for 7 days. The residual amount of melamine was analyzed by LC-MS/MS. The melamine concentration in muscle was estimated to be 3.7 mg/kg after 6 days of feeding with a diet containing 300 mg melamine/kg. After 2 days of culture with a melamine free diet, the residual melamine was depleted and the concentration had decreased from 1.15 mg/kg to 0.19 mg/kg in the muscle of catfish fed a diet containing 300 mg melamine/kg for 7 days. The residual amount of melamine was reduced to 0.03 mg/kg in muscle after 7 days of culture with a melamine free diet and was undetectable after a prolonged culture period of 14 days. Catfish tend to excrete melamine rapidly after oral administration and changes in body color were not observed during the short dosing period.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.3
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• pp.323-329
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• 2005

This study was conducted to investigate the effect of mycelia extracts of mushroom-cultured ginseng by-product on electron donating ability and proliferation of hepatic cancer cell (Hep3B) lines and sarcoma 180(S-180). The ginseng by-product was obtained from ginseng residues generated in processing of ginseng water extract. Mushroom strains used for preparation of mushroom mycelia cultured with ginseng residue were Phellinus linteus, Ganoderma lucidum, Coriolus versicolor and Lentinus edodes. The electron donating abilities of the test samples were increased in a dose-dependent manner in the range of 500ppm to 10,000ppm, and Coriolus versicolor extract showed the most potent activity among four mycelia extracts. In an anti-cancer test using Hep3B cells, ethanol extract showed higher antiproliferating effect than water extract. Ethanol extract of Lentinus edodes showed growth-inhibitory effect of 99.1% at 5,000ppm. All of mycelia extracts of mushroom showed the tumor suppressive effect in mice injected with S-180 cells. The growth­inhibitoy rates against tumor cells were 59% for Phellinus linteus, 61% for Ganoderma lucidum, 65% for Coriolus versicolor, 56% for Lentinus edodes. In conclusion, these results suggest that mycelia extracts of mushroom cultured with ginseng by-product have an antiproliferating effect against Hep3B cell and S-180 tumor cells.

• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.305-310
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• 2009

Yellow poplar was selected a promising biomass resources for bio-ethanol production through alkali prehydrolysis, enzymatic saccharification and fermentation using commercial cellulase mixtures (Celluclast 1.5L and Novozym 342 mixtures) and fermenting yeast. In alkali prehydrolysis, 51.1% of Yellow poplar biomass remained as residues, which chemical compositions were 82.2% of cellulose, 17.6% of xylan and 2.0% of lignin. In alkali prehydrolysis process, 96.9% of cellulose, 38.0% of xylan and 5.7% of lignin were remained. Enzymatic saccharification by commercial cellulases led to 87.0% of cellulose to glucose and 87.2% of xylan to xylose conversion. Produced glucose and xylose were fermented with fermenting yeast (Saccharomycess cerevisiae), which resulted in selective fermentation of glucose only to bio-ethanol. Residual monosaccharides after fermentation were consisted to 0.4-1.4% of glucose and 92.1-99.5% of xylose. Ethanol concentration was highest for 24 h fermentation as 57.2 g/L, but gradually decreased to 56.2 g/L for 48 h fermentation and 54.3 g/L for 72 h fermentation, due to the ethanol consumption by fermenting yeast.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.3
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• pp.289-300
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• 1997

Newborn dog chymosin was extracted from the stomachs of dogs of 2 weeks of age, and was purified by ion exchange chromatography. Half of the sequence was determined by amino acid sequencing and the complete sequence was deduced from a cloned chymosin cDNA Results showed that the zymogen showed 79% sequence identity with calf prochymosin and 54% identity with porcine pepsinogen A The size of the propart and location of the residue which becomes the amino-terminus in the active enzyme was the same in the prochymosins. The maximum general proteolytic activity at pH 3.2 of newborn dog chymosin was 3-4% of that of porcine pepsin A at pH 2, whereas the milk clotting activity relative to the general proteolytic activity of newborn dog chymosin was much higher than that of calf chymosin. Agar gel electrophoresis at pH 5.2 of stomach extracts of individual dogs showed the existence of two predominant genetic variants of zymogen and enzyme. The two variants could not be distinguished by amino acid composition or amino-terminal sequencing, and no differences in the enzymatic properties of the genetic variants were observed. It was concluded that of the residues that participate in the substrate binding, calf and newborn dog chymosin differ in the following positions (porcine pepsin numbering, subsites in parentheses) : Ser 12 Thr(S$_4$), Leu 30 Val(S$_1$/S$_3$), His 74 Gln(S'$_2$), Val 111 Ile(S$_1$/S$_3$), Lys 220 Met(S$_4$). With regard to the low general proteolytic activity of newborn dog chymosin, the substitution Asp303 Val relative to calf chymosin may contribute to an explanation of this.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.461-468
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• 1999

Acetolactate synthase (ALS) catalyzes the first common reaction in the biosynthesis of branched-chain amino acids, valine, leucine, and isoleucine. ALS is the common target of several classes of structurally diverse herbicides, the triazolopyrimidines, the imidazolinones, the sulfonylureas, and pyrimidyl-oxy-benzoates. We examined ihibitory activities of newly synthesized triazolopyrimidine sulfonamide derivatives using partially purified ALS from barley. $IC_{50}$ values for the active derivatives are 0.5nM∼8$\mu$M. Among them TP1 and TP2 are the most potent ALS inhibitors with $IC_{50}$ values of 0.5nM and 1.6nM, respectively. These inhibitors are more potent in the inhibition of barley ALS than commercial herbicides, Metosulam ($IC_{50}$;3.6 nM), Flumetsulam ($IC_{50}$;126 nM), and Cadre ($IC_{50};4 {\mu}M$). The progress curves for inhibition of ALS by TP2 showed that the amount of inhibition increases with time. The inhibition of ALS by TP2 was mixed-type inhibition with respect to pyruvate. Dual inhibition analyses of TP2 versus an imidazolinone, Cadre, and Leu showed parallel and intercepting kinetic pattern, respectively. The results suggest that TP2 binds to ALS competively with Cadre but not with Leu. Chemical modification of cysteinly residues in ALS decreased the sensitivity of ALS to Leu, while the modification did not affect the sensitivity of ALS to TP2 and Cadre.