• The Korean Journal of Mycology
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• v.43 no.4
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• pp.286-289
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• 2015

Clubroot, caused by the obligate parasite Plasmodiophora brassicae, is a severe soilborne disease of Brassicaceae. Storage of clubroot gall is important for studies on pathogenicity and race identification. As the current storage method has been used for more than 100 years, a new storage method should be developed and the most efficient way maintaining pathogenicity should be determined. Effects of storage conditions with different storage periods on pathogenicity in galls of kimchi cabbage were examined in a greenhouse. The experiments were performed under six conditions and four temperatures in order to determine the most effective storage conditions for maintenance of pathogenicity. The most effective conditions for clubroot gall storage was the storage of whole gall at $-70^{\circ}C$ or storage of filtrate at the same temperature through eight layers of gauze after homogenization of the galls.

• Molecules and Cells
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• v.39 no.4
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• pp.286-291
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• 2016

Epstein-Barr virus (EBV) is the prototypical ${\gamma}$-herpesvirus and an obligate human pathogen that infects mainly epithelial cells and B cells, which can result in malignancies. EBV infects these target cells by fusing with the viral and cellular lipid bilayer membranes using multiple viral factors and host receptor(s) thus exhibiting a unique complexity in its entry machinery. To enter epithelial cells, EBV requires minimally the conserved core fusion machinery comprised of the glycoproteins gH/gL acting as the receptor-binding complex and gB as the fusogen. EBV can enter B cells using gp42, which binds tightly to gH/gL and interacts with host HLA class II, activating fusion. Previously, we published the individual crystal structures of EBV entry factors, such as gH/gL and gp42, the EBV/host receptor complex, gp42/HLA-DR1, and the fusion protein EBV gB in a postfusion conformation, which allowed us to identify structural determinants and regions critical for receptor-binding and membrane fusion. Recently, we reported different low resolution models of the EBV B cell entry triggering complex (gHgL/gp42/HLA class II) in "open" and "closed" states based on negative-stain single particle electron microscopy, which provide further mechanistic insights. This review summarizes the current knowledge of these key players in EBV entry and how their structures impact receptor-binding and the triggering of gB-mediated fusion.

• Journal of Microbiology and Biotechnology
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• v.23 no.1
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• pp.1-6
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• 2013

Tetanus is a specific infectious disease, which is often associated with catastrophic events such as earthquakes, traumas, and war wounds. The obligate anaerobe Clostridium tetani is the pathogen that causes tetanus. Once the infection of tetanus progresses to an advanced stage within the wounds of limbs, the rates of amputation and mortality increase manifold. Therefore, it is necessary to devise a rapid and sensitive point-of-care detection method for C. tetani so as to ensure an early diagnosis and clinical treatment of tetanus. In this study, we developed a detection method for C. tetani using loop-mediated isothermal amplification (LAMP) assay, wherein the C. tetani tetanus toxin gene was used as the target gene. The method was highly specific and sensitive, with a detection limit of 10 colony forming units (CFU)/ml, and allowed quantitative analysis. While detecting C. tetani in clinical samples, it was found that the LAMP results completely agreed with those of the traditional API 20A anaerobic bacteria identification test. As compared with the traditional API test and PCR assay, LAMP detection of C. tetani is simple and rapid, and the results can be identified through naked-eye observation. Therefore, it is an ideal and rapid point-of-care testing method for tetanus.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.468-472
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• 2013

Chrysanthemum is an economically important horticultural plant in many countries. The white rust is one of the most devastating diseases caused by an obligate fungal pathogen Puccinia horiana. This is being controlled mostly by application of chemicals. In Korea, 26 items are registered and 10 items contain 6 triazole compounds. To identify and to obtain the information of the drug target for triazoles, possible sterol 14-demethylase orthologues were extracted. From the draft genome information, the nucleotide sequence of the sterol 14-demethylase gene was identified. The amino acid sequence was deduced and the tertiary structure of the enzyme was predicted. This protein showed no less than 84% amino acid sequence identities to those of genus Puccinia and no more than 68% to those of other genus.

• Weed & Turfgrass Science
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• v.5 no.4
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• pp.256-259
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• 2016

An obligate plant pathogenic fungus Puccinia zoysiae Dietel, the causal agent of rust disease, which is implicated in the damage of zoysiagrass (Zoysia spp.) in Korea. The fungus is one of the important pathogens, which attacks and colonizes susceptible zoysiagrass. Zoysia rust disease was observed in Jangseong, Hoengseong and Hapcheon in 2014 and 2015, Korea. The typical symptoms of the disease appeared first as small white spots on the leaf and stem of zoysiagrass plants, and turn brownish, dark brown spores revealed on the lesions. Uredospores were light brown in color, ellipsoid or spherical in shape and $22.0{\sim}25.0{\times}15.0{\sim}17.5{\mu}m$ in size. On the basis of the morphological characteristics, the fungus was identified as P. zoysiae. Pathogenicity of the fungus was proved by artificial inoculation on Z. japonica. The rust disease firstly appeared approx. early or middle June and then increased middle of October in Korea. In field, Z. matrella ecotypes were more resistant than Z. japonica ecotypes against the pathogen. Disease response against the pathogen was different among ecotypes of each species, respectively.

• Research in Plant Disease
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• v.26 no.3
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• pp.183-189
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• 2020

Powdery mildew is a common and serious disease of the Cucurbitaceae including cucumber (Cucumis sativus) in most areas of the world. To identify causal agents of the powdery mildew and their physiological race(s), we collected cucumber leaves displaying typical symptoms of powdery mildew from different locations in Korea. Based on morphological and molecular characteristics, all powdery mildew isolates were identified as an obligate biotrophic fungal pathogen, Podosphaera xanthii. After inoculation at melon (Cucumis melo) differentials to identify the fungal race(s), P. xanthii isolate MI180427 and IC190611 were identified as race 1 which has been repeatedly reported as dominant race in Korea. However, another isolate SE180328 produced different disease response in the tested differentials, being identified as race 2 which has not been reported in Korea. To confirm the race of SE180328, we inoculated additional melon differentials and determined the isolate as race 2F that is the prevalent race of powdery mildew in Beijing, China. Report of this new race 2F in Korea will be helpful for future breeding programs to develop resistant varieties to this race.

• Journal of Biosystems Engineering
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• v.37 no.6
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• pp.420-428
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• 2012

Purpose: Porcine proliferative enteropathy(PPE), caused by the obligate intracellular bacterium Lawsonia intracellularis, is a widely distributed disease throughout the world causing substantial economic loss. The bacterial pathogen invades the intestinal epithelial cells which causes hyperplasia of the infected cells and leads to the process of disease pathogenesis. For diagnosing PPE in a pig farm in earlier stage, a rapid diagnosing test equipment is needed for farmers. To test the equipment appropriately, we prepare the samples and antibodies for rapid detecting the Lawsonia intracellularis in pig feces. Methods : To prepare the PPE infected samples, we sampled PPE suspected pig feces in a pig farm. To manufacture a anti-Lawsonia intracellularis antibody for capturing the Lawsonia intracellularis, the rabbit-anti LsaA synthetic peptide polyclonal antibody was inoculated to rabbits. To select the couple of antibodies which is most well sandwiched with the bacteria, ELISA test was done with PPE infected ileum samples. Finally, to verify the PPE infected feces which would be used to test the rapid kit, PCR test was done on the sampled PPE suspected feces Results : The rabbit-anti LsaA synthetic peptide polyclonal antibody is developed, and is verified to capture the bacterial well through the fluorescence antibody test. Also, we found that the monoclonal antibody and the polyclonal antibody could be used as couples for sandwiching the bacteria. Finally, through the PCR test for samples of pig feces, we could prepare the 150 PPE positive samples and 50 PPE negative samples. Conclusions : The manufactured polyclonal antibody and the imported monoclonal antibody could be used to capture the bacteria using the sandwich techniques. Also, the prepared PPE infected negative and positive samples could be used to test the performance of the rapid kit to capture the bacterium Lawsonia intracellularis.

• Journal of Life Science
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• v.26 no.6
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• pp.711-720
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• 2016

To determine the degree of common genes and the phylogenetic relationships among genome-sequenced 680 prokaryotes, the similarities among 4,631 clusters of orthologous groups of protein (COGs)’ presence/ absence and gene content trees were analyzed. The number of COGs was in the range of 103–2,199 (mean 1377.1) among 680 prokaryotes. Candidatus Nasuia deltocephalinicola str. NAS-ALF, an obligate symbiont with insects, showed the minimum COG, while Pseudomonas aeruginosa PAO1, an opportunistic pathogen, represented the maximum COG. The similarities between two prokaryotes were 49.30–99.78 % (mean 72.65%). Methanocaldococcus jannaschii DSM 2661 (hyperthermophilic and autotrophic, Euryarchaeota phylum) and Mesorhizobium loti MAFF303099 (mesophilic and symbiotic, alpha-Proteobacteria class) had the minimum amount of similarities. As gene content may represent the potential for an organism to adapt to each habitat, this may represent the history of prokaryotic evolution or the range of prokaryotic habitats at present on earth. COG content trees represented the following. First, two members of Chloroflexi phylum (Dehalogenimonas lykanthroporepellens BL-DC-9 and Dehalococcoides mccartyi 195) showed a greater relationship with Archaea than other Eubacteria. Second, members of the same phylum or class in the 16S rRNA gene were separated in the COG content tree. Finally, delta- and epsilon-Proteobacteria were in different lineages with other Proteobacteria classes in neighbor-joining (NJ) and maximum likelihood (ML) trees. The results of this study would be valuable to identifying the origins of organisms, functional relationships, and useful genes.