• Proceedings of the Microbiological Society of Korea Conference
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• 2007.05a
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• pp.120-122
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• 2007

All living organisms use numerous signal-transduction pathways to sense and respond to their environments and thereby survive and proliferate in a range of biological niches. Molecular dissection of these signalling networks has increased our understanding of these communication processes and provides a platform for therapeutic intervention when these pathways malfunction in disease states, including infection. Owing to the expanding availability of sequenced genomes, a wealth of genetic and molecular tools and the conservation of signalling networks, members of the fungal kingdom serve as excellent model systems for more complex, multicellular organisms. Here, we employed Cryptococcus neoformans as a model system to understand how fungal-signalling circuits operate at the molecular level to sense and respond to a plethora of environmental stresses, including osmoticshock, UV, high temperature, oxidative stress and toxic drugs/metabolites. The stress-activated p38/Hog1 MAPK pathway is structurally conserved in many organisms as diverse as yeast and mammals, but its regulation is uniquely specialized in a majority of clinical Cryptococcus neoformans serotype A and D strains to control differentiation and virulence factor regulation. C. neoformans Hog1 MAPK is controlled by Pbs2 MAPK kinase (MAPKK). The Pbs2-Hog1 MAPK cascade is controlled by the fungal "two-component" system that is composed of a response regulator, Ssk1, and multiple sensor kinases, including two-component.like (Tco) 1 and Tco2. Tco1 and Tco2 play shared and distinct roles in stress responses and drug sensitivity through the Hog1 MAPK system. Furthermore, each sensor kinase mediates unique cellular functions for virulence and morphological differentiation. We also identified and characterized the Ssk2 MAPKKK upstream of the MAPKK Pbs2 and the MAPK Hog1 in C. neoformans. The SSK2 gene was identified as a potential component responsible for differential Hog1 regulation between the serotype D sibling f1 strains B3501 and B3502 through comparative analysis of their meiotic map with the meiotic segregation of Hog1-dependent sensitivity to the fungicide fludioxonil. Ssk2 is the only polymorphic component in the Hog1 MAPK module, including two coding sequence changes between the SSK2 alleles in B3501 and B3502 strains. To further support this finding, the SSK2 allele exchange completely swapped Hog1-related phenotypes between B3501 and B3502 strains. In the serotype A strain H99, disruption of the SSK2 gene dramatically enhanced capsule biosynthesis and mating efficiency, similar to pbs2 and hog1 mutations. Furthermore, ssk2, pbs2, and hog1 mutants are all hypersensitive to a variety of stresses and completely resistant to fludioxonil. Taken together, these findings indicate that Ssk2 is the critical interface protein connecting the two-component system and the Pbs2-Hog1 pathway in C. neoformans.

• The Journal of the Korean Society for Microbiology
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• v.13 no.1
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• pp.7-16
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• 1978

One hundred and three clinical isolates of enterococci were examined for susceptibility to 8 antibiotics, and transferability and transfer frequency of R plasmid. Ampicillin was the most active, followed in decreasing order by rifampin, amikacin and chloramphenicol, and tetracycline. High-level resistance(${\geq}2,000{\mu}g/ml$) to kanamycin, streptomycin, and gentamicin, known as the most active of the aminoglycosides to enterococcus, was present in 26.2%, 21.4%, and 18.3% of the isolates, respectively. In the drug susceptibility of the species, S. zymogenes was the most resistant and S. durans was the most sensitive to tested antibiotics. We could observed the transferability of enterococcal R plasmid in mixed culture: among the 28 strains which showed multiple drug resistance, 17 strains transferred all or part of their resistance with $2{\times}10^{-4}-2{\times}10^{-6}%$ of transfer frequency to a plasmid-free recipient, S. faecalis strain JH 2-2.

• Korean Journal of Microbiology
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• v.30 no.5
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• pp.360-365
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• 1992

Clinical isolates of 8 ofloxacin resistant Staphylococcus auresu (ORSA) were subjected to MIC test, Southern analysis on gyrA locus and nucleotide sequence analysis of 290 bp of gyrA gene (gyrA-290) spanning amino acid 26 to 121 in order to understand the mechanism of quinolone resistance in Staphylococcus aureus. ORSAs showed highlevel resistance against quinolones (8-250 fold increase of MICs) and also significant resistance agianst ${\beta}-lactams$ (2-32 fold increase of MICs). However, ORSs did not show any change in sensitivity agianst vancomycin. Southern analysis of ORSAs with HindIII, PstI and AluI revealed RFLPs on gyrA locus. In order to further analyze the gyrA gene, gyrA-290 was amplified by PCR and cloned to pTZ vector. Subsequent nucleic acid sequence analysis of gyrA-290 demonstrated a point mutation of C to T resulting amino acid change of Ser-84 to Leu-84 in all 8 ORSA strains. The substitution at 84th amino acid of tyrase A might confer one mechanism of high level quinolone resistance in Staphylococcus aureus.

• Journal of Life Science
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• v.17 no.5 s.85
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• pp.723-727
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• 2007

Resistance to metronidazole in Helicobacter pylori results from inactivation of rdxA and frxA, the chromosomal genes for a nitroreductase that normally converts metronidazole from prodrug to bactericidal agent. Two types of metronidazole susceptible strains had been found distinguishable by their apparent levels of frxA expression. Most common in the populations we had studied were strains that required only rdxA inactivation to become resistant to moderate levels of metronidazole(type I strains). The second strain type required inactivation of both frxA and rdxA to become resistance to metronidazole(type II strains): this was linked to a relatively high level of frxA gene transcription in the type II strains. The fdxA gene regulated fdxA as well as rdxA gene. Thus, to study the function of fdxA as a regulatory gene we constructed a null mutant of fdxA in H. pylori genome and identified over-and under-expressed proteins by fdxA using two-dimensional(2-D) electrophoresis and MALDI-TOP-MS. There were four over-expressed proteins in fdxA mutant; nifU-like protein(HP0221), frxA(HP0642), nonheme ferritin(HP0653), and hypothetical protein(HP0902). Three under-expressed proteins were also identified in fdxA mutant, including 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (HP0089), (3R)-hydroxymyristoyl ACP dehydratase(HP1376), and thioredoxin(HP1458).

• Food Science of Animal Resources
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• v.30 no.2
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• pp.179-184
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• 2010

Escherichia coli O157:H7 is a food-borne pathogen that causes bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). We compared three selective media and evaluated the performance of immunomagnetic separation (IMS) for the detection of low levels of E. coli O157:H7 in ground beef and radish sprouts with different levels of background flora. Bulk food samples (500 g for each trial) were artificially inoculated with nalidixic acid-resistant E. coli O157:H7 at the lowest dose that would generate 20 partial-positive samples of 25 g each. All samples were homogenized in mTSB (225 mL) and incubated overnight at $37^{\circ}C$. IMS was performed using the enriched mTSB samples (1 mL) along with conventional spreads plated onto three different selective media: Sorbitol MacConkey agar (SMAC), Sorbitol MacConkey agar with cefixime and tellulite (CT-SMAC), and Sorbitol MacConkey agar with nalidixic acid (NAL-SMAC) as the gold standard. Two suspicious colonies from each medium were selected and confirmed usinga serological test after transfer to tryptic soy broth with yeast extract (TSAYE). CT-SMAC was better than SMAC for detecting E. coli O157:H7 in all food types. Although there was no statistical difference in the number of positive samples when using IMS vs. non-IMS techniques, more positive samples were detected when IMS was used in both ground beef and radish sprouts. It appears that the improvement was more significant in radish sprouts, which had a higher level of background flora than ground beef. The results also suggest that the combination of CT-SMAC and IMS is sufficient to recover low levels of E. coli O157:H7 in high background flora food samples.

• Korean Journal of Breeding Science
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• v.41 no.3
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• pp.342-345
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• 2009

"Hwaweon 2" was developed from an interspecific cross between Hwaseongbyeo and a wild species, Oryza rufipogon L. (IRGC 105491) based on marker-aided selection. The recurrent parent "Hwaseongbyeo" is a high grain quality cultivar with medium-maturity. Hwaweon 2 is nearly isogenic to Hwaseongbyeo except a small O. rufipogon introgression on chromosome 9. This segment was associated with genes controlling a number of traits including grain weight, heading date, culm length, and spikelets per panicle. The preliminary and replicated yield trial was conducted at Chungnam National University in 2004, 2005 and 2006. The local adaptability test was carried out by the National Seed Management Office (NSMO) in 2007 and 2008. This cultivar was registered to NSMO with a cultivar designated as "Hwaweon 2". This cultivar averaged 98cm in culm length and has a medium to late growth duration. This variety is resistant to stripe virus as the recurrent parent. Milled rice of "Hwaweon 2" is translucent and the grain quality traits are comparable to those of the recurrent parent. The yield potential of "Hwaweon 2" in grain is about 7.68 MT/ha at the ordinary fertilizer level about 14% higher than that of Hwaseongbyeo due to increase in grain weight and spikelets per panicle.

• Korean Journal of Breeding Science
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• v.41 no.3
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• pp.338-341
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• 2009

"Hwaweon 1" was developed from an interspecific cross between Hwaseongbyeo and a wild species, Oryza rufipogon L. (IRGC 105491) based on marker-aided selection. The recurrent parent "Hwaseongbyeo" is a high grain quality cultivar with medium-maturity. Hwaweon 1 is nearly isogenic to Hwaseongbyeo except a small O. rufipogon introgression on chromosome 8 harboring the gene for grain weight. The preliminary and replicated yield trial was conducted at Chungnam National University in 2004, 2005 and 2006. The local adaptability test was carried out by the National Seed Management Office (NSMO) in 2007 and 2008. This cultivar was registered to NSMO with a cultivar designated as "Hwaweon 1". This cultivar averaged 89 cm in culm length and has a medium growth duration. This cultivar is resistant to stripe virus as the recurrent parent, Hwaseongbyeo. Milled rice of "Hwaweon 1" is translucent and the grain quality traits are comparable to those of the recurrent parent. The yield potential of "Hwaweon 1" in grain is about 7.43 MT/ha at the ordinary fertilizer level about 10% higher than that of Hwaseongbyeo mainly due to increase in grain weight.

• Korean Journal of Breeding Science
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• v.50 no.4
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• pp.497-503
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• 2018

A strawberry variety 'Arihyang' was derived as an artificial cross between 'Tochiotome' and 'Seolhyang' in 2014. The seedling and line selections were conducted from 2014 to 2015. Preliminary and advanced yield trials of '14-5-5,' which was the final selected line, were conducted from 2015 to 2017. 'Arihyang' is suitable for forced cultivation and has strong plant vigor, uniformly large-sized fruit, and a high yield compared to those of the check variety, 'Seolhyang' and 'Maehyang.' Especially, vitamin C was at a significant level, which was approximately 15% higher than that of 'Seolhyang.' The average number of flowers per first flower cluster was 10.5, which could reduce the labor of thinning fruit. Its fruit has a conical shape, dark red color, and glossy skin. The fruit was of good quality but has recommendations for harvest at the fully ripened stage. 'Arihyang' has intermediate resistant to phytophthora crown rot, but is susceptible to powdery mildew, gray mold, anthracnose, and fusarium wilt. It is reguired to manage major diseases and pests using optimum cultivation techniques and chemical control.

• Horticultural Science & Technology
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• v.29 no.5
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• pp.474-481
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• 2011

Potato late blight caused by the fungus Phytophthora infestans is one of the most vital diseases damaging the potato plant. It is for this reason that breeding potato cultivars resistant to late blight is now becoming a major concern around the world. The B3C1 clones has been introduced by the Highland Agriculture Research Center, RDA. The clones which came from International Potato Center in 2005 have a durable resistance to late blight. The clones were bred under a short-day condition in Peru. However, there was still no report on the adaptability of these clones to the long-day condition in Korea. Therefore, this study was conducted to evaluate the late blight resistance and major agronomic characteristics of B3C1 clones under Korea's long-day condition. This study was also done to generate genetic resources for developing new varieties resistant to late blight. In this study it was found out that in naturally infested field with P. infestans, AUDPC (area under disease progress curve) values of all B3C1 clones were significantly lower than those of the control varieties, 'Superior', 'Atlantic', and 'Haryeong'. It was found out that B3C1 clones had a high level of resistance to late blight and that they could be used as genetic resources to breed potato varieties with late blight resistance. However, several undesirable characteristics such as extremely late maturity, excessive growth of stems and stolons, and production of tubers that cannot easily be removed from the stolons were also observed. Among the twenty B3C1 clones, two clones, LB-8 (CIP393077.159) and LB-11 (CIP393371.159), were selected for cultivating at the highland area of Korea. Two B3C1 clones were crossed with Korean breeding lines and clonal selection for the progenies is still in progress.

• Journal of Nutrition and Health
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• v.48 no.2
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• pp.157-166
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• 2015

Purpose: The effects of water extract and distillate from the mixture of black goat meat and medicinal herb on MG-63 osteoblast proliferation and mouse bone marrow derived osteoclast formation were investigated. Methods: Proximate composition, volatile basic nitrogen (VBN), mineral content, free amino acid composition and free fatty acid composition in black goat meat were determined. Water extract and distillate were prepared with three groups; goat meat only (BG-E, BG-D), six herbs added group (BG-E6, BG-D6), and eight herbs added group (BG-E8, BG-D8). Osteoblast proliferation, mineralization and calcium uptake activity of MG-63 cells were measured and tartrate resistant acid phosphatase activity of osteoclasts was analyzed. Results: Black goat meat had remarkably low fat and high level of calcium. Glutamic acid was the most abundant amino acid. Herbs added extract groups (BG-E6 and BG-E8) showed increased MG-63 cell proliferation in a concentration dependent manner, while all the distillates did not show the effect. All extracts and distillates showed significantly increased osteoblast mineralization depending on the concentration. In particular, herb added extract, BG-E6, increased 170.3% of control and the distillate of BG-D and BG-D6 increased up to 168.5% and 159.8%, respectively. Calcium uptake activities of all water extracts showed remarkable increase of BG-E6 and BG-E8 up to 615.5% and 628.1% of control, respectively. Ditillates had no effect except BG-D6. All water extracts significantly reduced the activity of tartrate-resistant acid phosphatase (TRAP) in osteoclasts derived from mouse bone marrow. Conclusion: Combination of black goat meat and medicinal herb increased the MG-63 cell proliferation and effectively inhibited osteoclast differentiation in both water extracts and distillate of them, which implies that they could be used as potent functional food materials for bone health.