• Korean Journal of Veterinary Research
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• v.41 no.2
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• pp.177-188
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• 2001

Mastitis is one of the most significant cause of economic loss to the dairy industry. Especially, Staphylococcus aureus is a major contagious mastitis-causing pathogen in dairy cattle. Because of its high transmission rate and resistance to antibiotic therapy, staphylococcal mastitis presents a constant threat to the dairy industry. Staphylococcal enterotoxin C(SEC) produced by S aureus has been known as one of superantigens which are able to stimulate a large proportion of T lymphocytes independently of their antigenic specificity. In this experiment, we have conducted preliminary studies with mice and lactating cows to evaluate the immunogenicity and safety of the experimental vaccine consists of SEC mutant antigen on controlling the bovine mastitis associated with S aureus infections. The average value of somatic cell counts in quarter milk, isolation rate of S aureus were consistently decreased in SEC-SER vaccinated groups, whereas antibody titers were highly increased in SEC-SER vaccinated groups. Peripheral blood were also collected from the lactating cows to determine the proportion of leukocyte subpopulation associated with humoral immunity(HI) and cell mediated immunity(CMI). Proportion of leukocyte subpopulation expressing $BoCD2^+$(total T lymphocyte), $BoCD4^+$(T helper cell), $BoCD8^+$(T cytotoxic/suppressor cell) and NonT/NonB lymphocyte which are involved in CMI in SEC-SER vaccinated groups were decreased for the initial stage after first vaccination and then increased from ten weeks after first vaccination maintaining elevated level till 14 weeks after vaccination. In contrast, proportion of monocyte, MHC class II and B lymphocyte which are associated with the production of primary immune response in SEC-SER vaccinated groups were increased for the initial period and then decreased from ten weeks after first vaccination. We present evidence that vaccination of SEC-SER mutant antigen in lactating cows induced a significant proliferation of bovine T lymphocytes. These results suggest that SEC-SER mutant antigen used in this experiment might be one of potential immunogen in developing innovative vaccine against bovine IMI associated with S aureus. Additional challenge trials should be carried out to evaluate substantial protection against S aureus under the commercial farm conditions.

• Journal of Applied Biological Chemistry
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• v.59 no.4
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• pp.351-356
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• 2016

Bacterial blotch caused by Pseudomonas tolaasii is one of the major diseases of oyster mushroom, Pleurotus ostreatus. Application of bacteriophages is a very useful tool to decrease the density of pathogens and it has been successful to making disease-free cultivation area, known as phage therapy. Effect of phages on pathogen sterilization is very limited to the specific host strains. Minor variations of the host strains may cause changes in phage sensitivity. The phage-resistant strains of P. tolaasii were isolated and their pathogenic characters were investigated to improve the effectiveness of phage therapy. In the phylogenetic analysis, both phage-resistant strains and the corresponding host strains were identical based on the sequence comparison of 16S rRNA genes. The pathogenic characters, such as hemolytic activity and brown blotch formation, were measured on the phage-resistant strains and no correlation between phage-resistance and pathogenic characters was observed. Nevertheless, pathogenic characters were sometimes changed in the phage-resistant strains depending on the host strains. In order to make the phage therapy successful, the bacteriophages having a wide host range should be isolated.

• Korean journal of applied entomology
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• v.25 no.2 s.67
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• pp.63-70
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• 1986

Severity of incidence of white rot on apple fruit ranged from 5 to 16% and averaged 9% over major apple growing area in 1981. An isolate of Botryosphaeria ribis obtained from rotted apples developed lesions on leaves, branches and fruits of apple, pear, peach and grape in a series of wound inoculation test. B. ribis grew well on both potato sucrose agar and oatmeal agar. The best condition for vegetative growth on these two media was at $25{\sim}30^{\circ}C$ pH 4 and $10{\sim}15%$ sucrose content under light illumination. Rot development on fruit was first observed in the orchard at early August when sugar content in fruit reached 9.0%. Thereafter, number of rotted apples increased as sugar content increased. There was no correlation between the pH of juice of fruit and rot incidence. Infection on fruit began to occur as early as mid-June when young fruits were formed and infections were continued until harvest. When apple fruits were collected at 10-day intervals from the orchard beginning from early June and were wound-inoculated with B. ribis, rot lesion developed regardless of the stage of fruit growth. Incidence of white rot in the orchard was severe on Golden-delicious and Yukou, intermediate on Aoli, Fugi and Indo, and least on Jonathan and Red-delicious.

• Journal of Life Science
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• v.16 no.4
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• pp.664-671
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• 2006

We obtained 424 Salmonella enterica serovar Typhi isolates from sporadic cases of infection in Busan during 1996 to 2005. We investigated the trend of antimicrobial resistance and molecular typing by pulsed-field gel electrophoresis (PFGE). Of the total 424 isolates, 6 strains (1.4%) were multidrug-resistant (MDR) S. enterica serovar Typhi isolates, 2 strains (0.5%) were resistant to only nalidixic acid, and the remaining 416 strains (98.1%) were fully susceptible to the 18 antimicrobial agent. PFGE of XbaI-digested chromosomal DNA was performed on 50 sporadic S. enterica serovar Typhi isolates with the objective of investigating the extent of genetic diversity of these isolates in our region. We could find that these isolates were much more heterogeneous and at least 32 different PFGE patterns were generated according by dice coefficient, between 0.69 and 1.0. Restriction fragment patterns consisted of 13 to 18 fragments ranged in size from 20 to 630 kb. The results confirmed that PFGE would be an useful tool for investigating surveillance of sporadic or outbreak case and assessing clonality for S. enterica serovar Typhi in Busan area. Our finding will be valuable in developing rational strategies to control this pathogen and setting the basis of an effective PulseNet system in Korea.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.273-273
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• 2013

Recently, Point-of-care (POC) testing microdevices enable to do the patient monitoring, drug screening, pathogen detection in the outside of hospital. Immunochromatographic strip (ICS) is one of the diagnostic technologies which are widely applied to POC detection. Relatively low cost, simplicity to use, easy interpretations of the diagnostic results and high stability under any circumstances are representative advantages of POC diagnosis. It would provide colorimetric results more conveniently, if the genetic analysis microsystem incorporates the ICS as a detector part. In this work, we develop a reverse transcriptase-polymerase chain reaction (RT-PCR) microfluidic device integrated with a ROSGENE strip for colorimetric influenza H1N1 virus detection. The integrated RT-PCR- ROSGENE device is consist of four functional units which are a pneumatic micropump for sample loading, 2 ${\mu}L$ volume RT-PCR chamber for target gene amplification, a resistance temperature detector (RTD) electrode for temperature control, and a ROSGENE strip for target gene detection. The device was fabricated by combining four layers: First wafer is for RTD microfabrication, the second wafer is for PCR chamber at the bottom and micropump channel on the top, the third is the monolithic PDMS, and the fourth is the manifold for micropump operation. The RT-PCR was performed with subtype specific forward and reverse primers which were labeled with Texas-red, serving as a fluorescent hapten. A biotin-dUTP was used to insert biotin moieties in the PCR amplicons, during the RT-PCR. The RT-PCR amplicons were loaded in the sample application area, and they were conjugated with Au NP-labeled hapten-antibody. The test band embedded with streptavidins captures the biotin labeled amplicons and we can see violet colorimetric signals if the target gene was amplified with the control line. The off-chip RT-PCR amplicons of the influenza H1N1 virus were analyzed with a ROSGENE strip in comparison with an agarose gel electrophoresis. The intensities of test line was proportional to the template quantity and the detection sensitivity of the strip was better than that of the agarose gel. The test band of the ROSGENE strip could be observed with only 10 copies of a RNA template by the naked eyes. For the on-chip RT-PCR-ROSGENE experiments, a RT-PCR cocktail was injected into the chamber from the inlet reservoir to the waste outlet by the micro-pump actuation. After filling without bubbles inside the chamber, a RT-PCR thermal cycling was executed for 2 hours with all the microvalves closed to isolate the PCR chamber. After thermal cycling, the RT-PCR product was delivered to the attached ROSGENE strip through the outlet reservoir. After dropping 40 ${\mu}L$ of an eluant buffer at the end of the strip, the violet test line was detected as a H1N1 virus indicator, while the negative experiment only revealed a control line and while the positive experiment a control and a test line was appeared.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.626-632
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• 2013

In the course of a developing screening method for resistant radish to Fusarium oxysporum f. sp. raphani, we found that the fungus produces phytotoxic compound against Raphanus sativus. The culture filtrate of F. oxysporum f. sp. raphani KR1 represented the strongest phytotoxicity when the fungus was incubated in the malt extract broth with 150 rpm at $25^{\circ}C$ for 14 days. Under bioassay-guided purification, we isolated a substance from liquid culture of F. oxysporum f. sp. raphani KR1, with phytotoxic effect against R. sativus. The compound was identified as fusaric acid by mass and nuclear magnetic resonance spectral analyses. Phytotoxicity of the compound against cruciferous vegetable crops, including radish, cabbage, and broccoli, was investigated. Fusaric acid represented phytotoxicity on radish seedlings by concentration dependant manner. And the phytotoxin demonstrated strong phytotoxicity on the resistant cultivars as well as susceptible cultivars of radish to F. oxysporum f. sp. raphani. In addition, fusaric acid isolated from the fungus also showed a potent phytotoxic efficacy against non-host Brassicaceae crops of the fungus such as cabbage and broccoli. The results demonstrate that fusaric acid produced by F. oxysporum f. sp. raphani is non-host-specific toxin and for screening of resistant radish to the fungal pathogen, spore suspension of the fungus without the phytotoxin has to be used.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.344-347
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• 2008

"Nunbora" is a new japonica rice cultivar developed from a cross between Iksan433 resistant to bacterial blight and Miyadamamochi, a waxy line. at Honam Agricultural Research Institute, NICS, RDA, in 2006. This cultivar is a short grain shape and about 118 days of growth duration from transplanting "Nunbora" to harvesting under Korean climatic conditions. The milled rice are snow white and glutinuous. This cultivar shows high resistant reactions to the bacterial blight pathogen race $K_1{\sim}K_3$ and blast respectively. The milled rice yield of "Nunbora" is about 5.34 MT/ha under the standard fertilizer level of the ordinary transplanting cultivation. "Nunbora" would be adaptable for in the middle plain, north middle-mountin plain and Honam plain, and Youngnam plain areas of Korea.

• Journal of Bio-Environment Control
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• v.28 no.3
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• pp.212-217
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• 2019

Bacterial wilt caused by Ralstonia solanacearum is a major disease that affects tomato plants widely. R. solanacearum is a soil born pathogen which limits the disease control measures. Therefore, breeding of resistant tomato variety to this disease is important. To identify the susceptible variety, degree of disease resistance has to be determined. In this study, micro sap flow sensor is used for accurate prediction of resistant degree. The sensor is designed to measure sap flow and water use in stems of plants. Using this sensor, the susceptibility to bacterial wilt disease can be identified two to three days prior to the onsite of symptoms after innoculation of R. solanacearum. Thus, this find of diagnosis approach can be utilized for the early detection of bacterial wilt disease.

• Research in Plant Disease
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• v.28 no.1
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• pp.19-25
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• 2022

Ginseng is an important medicinal plant cultivated in East Asia for thousands of years. It is typically cultivated in the same field for 4 to 6 years and is exposed to a variety of pathogens. Among them, ginseng root rot is the main reason that leads to the most severe losses. In this study, endophytic bacteria were isolated from healthy ginseng, and endophytes with antagonistic effect against ginseng root rot pathogens were screened out. Among the 17 strains, three carried antagonistic effect, and were resistant to radicicol that is a mycotoxin produced by ginseng root rot pathogens. Finally, Bacillus velezensis CH-15 was selected due to excellent antagonistic effect and radicicol resistance. When CH-15 was inoculated on ginseng root, it not only inhibited the mycelial growth of the pathogen, but also inhibited the progression of disease. CH-15 also carried biosynthetic genes for bacillomycin D, iturin A, bacilysin, and surfactin. In addition, CH-15 culture filtrate significantly inhibited the growth and conidial germination of pathogens. This study shows that endophytic bacterium CH-15 had antagonistic effect on ginseng root rot pathogens and inhibited the progression of ginseng root rot. We expected that this strain can be a microbial agent to suppress ginseng root rot.

• Korean Journal of Plant Resources
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• v.36 no.1
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• pp.100-106
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• 2023

In order to control the fire blight disease, all plants within the radius of the diseased orchard were removed in the early stage of the outbreak, or antibiotics control was performed for prevention. Since the beginning of antibiotics use on plants, the potential for development of resistance to antibiotics by the plant pathogen and unintended detrimental effects on the fruit trees and environment has become a problem. The purpose of this study is to determine the degree of phytotoxicity to fruit trees caused by excessive spraying of the fire blight disease disinfectant and to establish basic data for safe disinfectant guide. We analyzed whether damage to the fruit tree and the maximum residual limit of fruit was exceeded when three kinds of the fire blight disease disinfectants were continuously sprayed in excess of the number of safe use during the growing season. There was no phytotoxicity in apple 'Fuji' and pear 'Niitaka', and oxolinic acid was detected beyond the limit of quantitation in 'Fuji' grown without a bag, and the other disinfectants were detected below the maximum residue limit. When these disinfectants are continuously sprayed in excess of the number of safe, phytotoxicity may remain on the fruit. Therefore, it is necessary to observe the prescribed dilution factor and observe the safe frequency and the timing of use.