• Korean Journal of Food Science and Technology
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• v.51 no.4
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• pp.316-323
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• 2019

It is difficult to analyze pymetrozine in citrus fruits using the hydromatrix method because of its low efficiency of purification and overlap of matrix and pymetrozine peaks. Liquid-liquid extraction can analyze pymetrozine in citrus fruits using dichloromethane. Since low pH interferes with the extraction of pymetrozine, the extracts of citrus fruits were maintained over pH 7.0 by adding borax buffer and 1 N NaOH in the improved method. According to the improved method, citrus fruits (such as lemon, lime, orange, tangerine, and grapefruit) were extracted and purified for HPLC-photo diode array analysis. The results of validation were as follows: $4.360{\mu}g/kg$ of limit of detection, $14.533{\mu}g/kg$ of limit of quantitation, and 0.007 mg/kg of method quantitative limit. Citrus fruits spiked with pymetrozine showed a recovery range from 71.8 to 83.7% and a coefficient of variation below 6%. Thus, the improved method can efficiently analyze pymetrozine in citrus fruits.

• Korean Journal of Poultry Science
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• v.46 no.3
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• pp.161-171
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• 2019

Four-week-old male Korean native chicks (KNC) were assigned to 3 groups with 6 replicates (8 birds/replicate) in each group: a basal diet (CON, 100 ppm of Zn), basal diet fortified with 50 ppm of Zn with zinc oxide (ZnO), or basal diet fortified with 50 ppm of Zn with Zn-methionine (ZnM). Immediately after a 4-week-feeding trial, 6 birds per group were used to evaluate the effects of zinc supplements on antioxidant indicators and the mRNA expression of zinc transport genes. The nitrogen components, lipid peroxidation, and total antioxidant status in blood were not influenced by Zn fortified diets. However, the ZnM group showed a significant (P<0.05) increase in uric acid levels than those in the ZnO group. In the small intestine, superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities, and malondialdehyde (MDA) level were unaffected by zinc supplements. The activity of glutathione S-transferase (GST) was significantly (P<0.05) enhanced by Zn-methionine supplementation. In the liver, the activity of GST was significantly (P<0.05) increased by Zn-methionine supplement without affecting SOD, GPX, and MDA levels. With respect to the mRNA expression of zinc transport genes, the ZnM group displayed a strong tendency for increases in intestinal ZnT-1 (P=0.09) and ZnT-5 (P=0.06) levels, compared to those in the CON group. Moreover, the ZnM group showed a tendency (P=0.10) for up-regulation of hepatic metallothionein mRNA as compared with the CON group. In conclusion, the Zn-fortified diet with 50 ppm of Zn-methionine helped to improve GST activity and Zn transport gene expression in the small intestine or liver of KNC.

• Research in Plant Disease
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• v.25 no.3
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• pp.108-113
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• 2019

Almost 30% of arable lands of North Korea are covered with paddy rice. In rice cultivation of North Korea, rice blast disease is the most important fungal disease and bacterial leaf blight is the most important bacterial disease. Seven North Korean rice cultivars had been tested for the disease resistance against rice blast pathogen, Magnaporthe oryzae and bacterial leaf blight pathogen, Xanthomonas oryzae pv. oryzae. The responses of seven cultivars against 17 different M. oryzae races from South Korea had been quite different. Among seven cultivars, Giljoo1ho was very resistant to all 18 different M. oryzae isolates from South Korea, nevertheless KI or KJ. Pyungdo5ho was very susceptible, it showed susceptible responses to 8 out of 10 KI races and 7 out of 8 KJ races of M. oryzae isolated in South Korea. However, the response to bacterial leaf blight was different from the response to rice blast pathogen. Gijoo1ho, Wonsan69ho, Onpo1ho, and Pyungdo15ho were susceptible to KXO42 (K1) and KXO90 (K2), respectively. Pyungdo5ho was resistant to KXO85 (K1) and KXO19 (K3), and Pyungyang21ho was resistant to K1 races. Based on these results, Giljoo1ho can be a good resource for the breeding of resistant rice cultivar against M. oryzae isolates from South Korea.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.2
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• pp.127-133
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• 2019

Purpose: The purpose of present study was to investigate fracture strength and mode of failure of endodontically treated teeth restored with metal cast post-core system, prefabricated fiber post system, and newly introduced polyetherketoneketone (PEKK) post-core system. Materials and methods: A total of 21 mandibular premolar were randomly grouped into 3 groups of 7 each according to the post material. Group A was for metal cast post core; Group B for prefabricated glass fiber post and resin core; and Group C for milled PEKK post cores. All specimens were restored with metal crown. The fracture strength of each specimen was measured by applying a static load of 135-degree to the tooth at 2 mm/min crosshead speed using a universal testing machine. After the fracture strength measurement, the mode of failure was observed. The results were analyzed using Kruscal-Wallis test and post hoc Mann-Whitney U test at confidence interval ${\alpha}=.05$. Results: Fracture resistance of PEKK post core was lower than those of cast metal post and fiber reinforced post with composite resin core. In the aspect of fracture mode most of the root fracture occurred in the metal post core, whereas the post detachment occurred mainly in the fiber reinforced post. In the case of PEKK post core, teeth and post were fractured together. Conclusion: It is necessary to select appropriate materials of post for extensively damaged teeth restoration and clinical application of the PEKK post seems to require more research on improvement of strength.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.369-378
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• 2018

This study was conducted to evaluate effects of dietary microbial probiotics on the growth and disease resistance of olive flounder (Paralichthys olivaceus) in a recirculating aquaculture system (RAS), and the effects of the probiotic bioaugmentation on the microbial community structure and water quality. For the analysis, 80 juvenile fish (average weight, $25.7{\pm}7.6g$; average length, $15.2{\pm}1.7cm$) were fed a basal diet containing a commercial microbial product CES-AQ1 (CES; $1{\times}10^9\;CFU/kg$ diet) in an RAS for 8 weeks. Weight gain, the specific growth rate, feed efficiency, and protein efficiency ratio of the fish fed the CES diet in the RAS were 1.5~2.5 times higher than those of fish fed the basal diet alone, or the basal diet containing oxytetracycline (OTC), yeast plus bacterium, or Bacillus subtilis in a still water system. There was no significant difference in the pathogen challenge test between fish fed the OTC diet and fish fed the CES diet in the RAS, suggesting the CES-AQ1 probiotic used in the RAS as a potential replacement for antibiotics. The RAS biofilter maintained the highest microbial diversity and appeared to harbor microbial communities with ammonium oxidation, denitrification, and fish pathogen suppression functions. Ammonia, which is hazardous to fish, was significantly decreased to < 0.5 mg/L in 19 days, indicating the effectiveness of probiotic supplementation to maintain good water quality in RAS. These results suggest that the intestinal microbial communities of fish are stabilized by a probiotic-containing diet (CES) and that bioaugmentation with probiotics may be an eco-friendly and economical supplement for aquaculture of olive flounder, promoting both good water quality and fish health in an RAS.

• Journal of the Korean Society of International Agriculture
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• v.30 no.4
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• pp.328-338
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• 2018

Central Asia (Uzbekistan, Kazakhstan, Kyrgyzstan) is a hot and arid continental climate, with most areas (68%) consisting of barren vegetation, desert, and meadows. The main agricultural areas for crop production include irrigated farmland, non-irrigated farmland, grassland, prairie and mountain. We are experiencing climate change with recent climate variability increasing. Agriculture is one of major economic sectors and provides a means of livings for the rural population of Central Asia, especially the poor. In the past two decades, Central Asia has experienced a high population growth rate, with Kazakhstan at 16.8%, Uzbekistan at 34.5% and Kyrgyzstan at 28.4%. As a major industry, Kazakhstan has the largest share of exports of agricultural products followed by petroleum, mineral resources, steel, and chemicals. Uzbekistan is the fifth largest cotton exporter as well as the sixth largest cotton producer in the world. Kyrgyzstan exports ores, stones, cultured pearls, and minerals. These three countries are rich in mineral resources, agricultural products, and energy resources. However, not only do they have difficulties in economic development due to the weakness of logistics and industrial infrastructure, but they also have imperceptible cooperation and investment among countries due to insufficient research and development. Through this study, we will investigate national outlook, economic indicators, major agricultural products, import and export status, and agricultural technology cooperation status, and study how Korean agricultural industry advances into these countries through SWOT analysis. Through this, we hope to contribute to the basic data of Central Asian studies and cooperation and investment in agriculture in each country. In addition, in order to increase cooperative exchange and investment in these countries, we will prepare a Central Asia logistics hub for the rapidly changing interKorean railroad era.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.278-286
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• 2019

Sesbania, an annual herb, is known for its high forage value and salt tolerance. It has merits as a forage crop that is adaptable to reclaimed land in the Republic of Korea. Therefore, we collected Sesbania genetic resources from the Republic of Korea and other countries, and conducted experiments to evaluate their potential as a forage crop in Korean climate and soil conditions. In the preliminary experiments, 15 genetic resources which were able to set seeds in Korean environment were selected out of a total of 46 collected genetic resources. Among 15 genetic resources, SL13 was the tallest and it was followed by that of SC04, SR01 and SE07. The accessions with the earliest flowering started flowering 101 days after sowing and set seed in early August. Fifteen accessions were evaluated for their salt tolerance at germination stage based on germination rate and growth of germinated seedlings at 0 mM, 150 mM and 300 mM NaCl concentrations. Five genetic resources like SC04, SL13, SS20, SS24 and SR01 were selected to be tolerant to NaCl treatment. Forage value was evaluated based on crude protein, acid detergent fiber, neutral detergent fiber and in vitro dry matter digestibility. The forage value of leaves was significantly higher than that of stems, and the forage value of the stem was slightly better than that of rice straw. The forage value of leaves of all the genetic resources was higher than grade 1 by the American Forage and Grassland Council grade. Among five selected genetic resources, the relative feed value of SC04 was the highest and it was followed by that of SS20, SL13, SS24 and SR01.

• Journal of Food Hygiene and Safety
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• v.36 no.1
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• pp.51-59
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• 2021

In this study we analyzed the elution rates of 11 metals from 82 metallic kitchen utensils purchased in the market. The elution frequency of the 11 types of metals was iron > aluminum > chromium, nickel > zinc > copper > lead > arsenic > antimony > stannum > cadmium. For metallic kitchen utensils, the elution rate of heavy metals was 7.3-93.9%, and the average elution concentration was 0.001-13.473 mg/L. The average elution concentration of heavy metals was ranged between none-detected (N. D.) to 30.473 mg/L for non-coated kitchen utensils and 0.000-10.005 mg/L for coated kitchen utensils. The average elution concentration of metals from domestic kitchen utensils ranged from 0.001-25.145 mg/L, and from 0.000-33.518 mg/L for imported kitchen utensils. In particular, aluminum was found to be high in domestic kitchen utensils while iron was high in imported kitchen utensils. The average elution concentration of heavy metals was N.D.-2.670 mg/L for stainless steel, N.D.- 31.575 mg/L for aluminum, and N.D.-307.737 mg/L for iron. The amount of transition to food after cooking was investigated.

• Korean Journal of Environmental Biology
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• v.39 no.2
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• pp.195-206
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• 2021

In 2020, South Korea initiated research and development of a longitudinal connectivity evaluation between upstream and downstream based on stream ecosystem health. This study analyzed the migration of upstream and downstream migratory fish species, fish distribution characteristics, trophic guilds, tolerance guilds, and species composition changes from 2015 to 2020 at Songrim weir in Yeongok stream, where the cross-structure of an ice harbor-type fishway for fish movement was recently improved. A total of 5,136 fish, including 36 species, were collected and three major migratory fishes were identified, namely, Tribolodon hakonensis, Plecoglossus altivelis altivelis, and Oncorhynchus keta. According to the comparative analysis before (Pre-I) and after (Post-I) improvement of the fishway, the relative abundance of primary freshwater fish increased in the upstream section, while the number of migratory fishes decreased. The fish species that used the fishway in the Songrim weir were Tribolodon hakonensis (58.4%) and Plecoglossus altivelis altivelis(11.8%). According to the Wilcoxon Signed-Rank Test migratory fish showed a statistically significant difference (p<0.05) in the upstream and downstream, showing a biological improvement effect of the crossstructure. On the other hand, the annual change of migratory fish based on the MannKendall trend test did not significantly increase or decrease (p>0.05). Therefore, in the fish passage improvement project, it is necessary not only for physical, hydrological, and structural tests, but also for pre- and post-biological tests on the use and improvement effect of fishway.

• Journal of Applied Biological Chemistry
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• v.64 no.2
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• pp.185-192
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• 2021

Psoriasis is a chronic intractable skin disease caused by various inflammatory cytokines such as IL-6, CXCL8, TNF-α, and IFN-γ, as well as IL-17A secreted from Th17 cells and is characterized by hyperkeratosis and chronic inflammation of the epidermis. Brazilin, an active ingredient of Caesalpinia sappan L., is known to exert antioxidant and anti-inflammatory activity, and function in skin barrier improvement. In particular, it was shown as a potential material for treating psoriasis in a tumor necrosis factor (TNF)-α-stimulated HaCaT keratinocyte model. However, the direct regulation of the C-C motif chemokine ligand (CCL) 20, a psoriasis-inducing factor, by brazilin has not been reported. Therefore, in this study, we investigated the suppression of CCL20 and the regulatory mechanism by brazilin using a psoriasis-like model. First, brazilin downregulated CCL20 and CXCL8 in IL-17A-stimulated HaCaT cells in a concentration-dependent manner by inhibiting signal transducer and transcription (STAT)3 phosphorylation. In addition, brazilin significantly inhibited the expression of psoriasis-related genes CXCL8, CCL20, IL-1, IL-6, and TNF-α in TNF-α/IL-17A/IFN-γ-stimulated HaCaT cells. Moreover, brazilin also had a positive effect on improving the skin barrier in TNF-α/IL-17A/IFN-γ-stimulated HaCaT cells. The above results indicated that brazilin ultimately downregulated CCL20 expression by inhibiting STAT3 phosphorylation, and also suppressed the expression of psoriasis-induced cytokines. If the efficacy of brazilin in improving psoriasis is verified through animal models and clinical trials in the future, it may represent a potentially therapeutic substance for psoriasis patients.