• 대한수의학회지
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• 제60권3호
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• pp.173-177
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• 2020

Edible offal is easily contaminated by Escherichia coli (E. coli) and fluoroquinolone (FQ)-resistant E. coli is considered a serious public health problem, thus, this study investigated the genetic characteristics of FQ-resistant E. coli from edible offal. A total of 22 FQ-resistant E. coli isolates were tested. A double mutation in each gyrA and parC led the highest MIC. Four (18.2%) isolates carried plasmid-mediated quinolone resistance genes. The fimH, eaeA, escV, astA, and iucC genes were confirmed. Seventeen isolates (77.3%) were positive for plasmid replicons. The isolates showed high genetic heterogeneity based on pulsed-field gel electrophoresis patterns.

• 한국자원식물학회지
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• 제29권6호
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• pp.658-669
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• 2016

Rice blast, caused by a fungus Magnaporthe oryzae, is one of the most devastating diseases of rice worldwide. Analyzing the valuable genetic resources is important in making progress towards blast resistance. Molecular screening of major rice blast resistance (R) genes was determined in 2,509 accessions of rice germplasm from different geographic regions of Asia and Europe using PCR based markers which showed linkage to twelve major blast R genes, Pik-p, Pi39, Pit, Pik-m, Pi-d(t)2, Pii, Pib, Pik, Pita, Pita/Pita-2, Pi5, and Piz-t. Out of 2,509 accessions, only two accessions had maximum nine blast resistance genes followed by eighteen accessions each with eight R genes. The polygenic combination of three genes was possessed by maximum number of accessions (824), while among others 48 accessions possessed seven genes, 119 accessions had six genes, 267 accessions had five genes, 487 accessions had four genes, 646 accessions had two genes, and 98 accessions had single R gene. The Pik-p gene appeared to be omnipresent and was detected in all germplasm. Furthermore, principal component analysis (PCA) indicated that Pita, Pita/Pita-2, Pi-d(t)2, Pib and Pit were the major genes responsible for resistance in the germplasm. The present investigation revealed that a set of 68 elite germplasm accessions would have a competitive edge over the current resistance donors being utilized in the breeding programs. Overall, these results might be useful to identify and incorporate the resistance genes from germplasm into elite cultivars through marker assisted selection in rice breeding.

• 생명과학회지
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• 제19권5호
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• pp.639-643
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• 2009

배추는 재배 온도에 따라 수확량과 품질에 많은 영향을 받을 수 있다. 고온 스트레스 저항성 배추품종 육성을 위해 본 연구는 스트레스 저항성에 관련이 있다고 알려진 trehalose 유전자 관련 다형성 마커를 개발하였다. 아라비돕시스 trehalose 합성 유전자와 유사한 총 28개의 배추 EST를 NCBI database에서 찾고 고온에 상대적으로 약한 지부품종과 고온에 잘 견디는 품종인 권심을 대상으로 다형성을 조사하였다. 이 중 10개의 EST에서 insertion/deletion 또는 single nucleotide polymorphism을 발견하여 이를 바탕으로 쉽게 이용이 가능한 10개의 다형성 PCR 마커를 개발하였다. 본 연구에서 개발된 trehalose 분자마커는 앞으로 배추 작물에서 환경 스트레스 저항성과 유전적 연관성을 확인하는데 이용될 수 있고 MAS를 이용한 품종육성에 이용될 수 있다고 기대된다.

• Biomolecules & Therapeutics
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• 제27권3호
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• pp.302-310
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• 2019

Melanoma cells have been shown to respond to BRAF inhibitors; however, intrinsic and acquired resistance limits their clinical application. In this study, we performed RNA-Seq analysis with BRAF inhibitor-sensitive (A375P) and -resistant (A375P/Mdr with acquired resistance and SK-MEL-2 with intrinsic resistance) melanoma cell lines, to reveal the genes and pathways potentially involved in intrinsic and acquired resistance to BRAF inhibitors. A total of 546 differentially expressed genes (DEGs), including 239 up-regulated and 307 down-regulated genes, were identified in both intrinsic and acquired resistant cells. Gene ontology (GO) analysis revealed that the top 10 biological processes associated with these genes included angiogenesis, immune response, cell adhesion, antigen processing and presentation, extracellular matrix organization, osteoblast differentiation, collagen catabolic process, viral entry into host cell, cell migration, and positive regulation of protein kinase B signaling. In addition, using the PAN-THER GO classification system, we showed that the highest enriched GOs targeted by the 546 DEGs were responses to cellular processes (ontology: biological process), binding (ontology: molecular function), and cell subcellular localization (ontology: cellular component). Ingenuity pathway analysis (IPA) network analysis showed a network that was common to two BRAF inhibitorresistant cells. Taken together, the present study may provide a useful platform to further reveal biological processes associated with BRAF inhibitor resistance, and present areas for therapeutic tool development to overcome BRAF inhibitor resistance.

• Animal Bioscience
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• 제34권4호
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• pp.734-742
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• 2021

Objective: The present study aimed to investigate the occurrence and species of coagulase-positive staphylococci (CoPS) and coagulase-negative staphylococci (CoNS) in retail pork meat samples collected during nationwide monitoring. The staphylococcal isolates were characterized for antimicrobial and zinc chloride resistance and enterotoxigenic potential. Methods: A total of 260 pre-packaged pork meat samples were collected from 35 retail markets in 8 provinces in Korea for isolation of staphylococci. Antimicrobial and zinc chloride resistance phenotypes, and genes associated with the resistance phenotypes were determined on the isolates. Furthermore, the presence and distribution of 19 staphylococcal enterotoxin (SE) genes and enterotoxin-like genes among the pork-associated staphylococci were determined by multiplex polymerase chain reaction-based assays using the specific primer sets. Results: A total of 29 staphylococcal strains (29/260, 11.1%) were isolated from samples of retail pork meat, 24 (83%) of which were CoNS. The four CoNS species identified were S. saprophyticus (n = 16, 55%), S. sciuri (n = 3, 10%), S. warneri (n = 3, 10%), and S. epidermidis (n = 2, 7%). Among the 29 isolates, four methicillin-resistant CoNS (MR-CoNS; three S. sciuri and one S. epidermidis) and one methicillin-resistant CoPS (MR-CoPS; one S. aureus) were identified. In addition, a relatively high level of tetracycline (TET) resistance (52%) was confirmed in CoNS, along with a predominant distribution of tet(K). The most prevalent SEs were sep (45%), and sen (28%), which were carried by 81% of S. saprophyticus. Conclusion: These findings suggest that CoNS, especially S. saprophyticus strains, in raw pork meat could be a potential risk factor for staphylococcal food poisoning (SFP), and therefore, requires further investigation to elucidate the role of SEls in SFP and virulence of the pathogen. Our results also suggest that CoNS from raw pork meat may act as a source for transmission of antimicrobial resistance genes such as staphylococcal cassette chromosome mec and tet(K).

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.67.2-68
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• 2003

A rice cultivar, Taebaegbyeo, is highly resistant to rice blast and moderately resistant to bacterial leaf blight (BLB) caused by Magnaporthe grisea and Xanthomonas oryzae pv. oryzae, respectively. To study the rice disease resistance mechanism, we generated rice deletion M3 mutants by gamma-ray irradiation. Blast and BLB responses of 16,000 M3 mutants were screened by inoculating mixtures of 4 races (KJ-201, H-1113a, KI-313, KI-409) of M. grisea and 3 Korean races of X. oryzae pv. oryzae. We selected so far 21 M3 mutants of Taebaegbyeo showing high susceptibility to the diseases. One of the mutants, KCT-6417, was susceptible to KI-1113a race of M. grisea, suggesting the deletion of a race-specific blast resistance gene in the mutant. To isolate rice genes involved in blast resistance and defense response, we take a PCR-based suppression subtractive hybridization approach using cDNAs of blast-inoculated wild type and the KCT-6417 as a tester and a driver, respectively. Genes specifically expressed in the wild type will be presented. The selected genes would give us a clue to understand mechanism for the race specific resistance and defense responses against M. grisea H-1113a in Taebaegbyeo.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2005년도 International Meeting of the Microbiological Society of Korea
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• pp.143-147
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• 2005

The non-pathogenic, non-glycopeptide-producing actinomycete Streptomyces coelicolor carries a cluster of seven genes (vanSRJKHAX) that confers inducible, high-level resistance to vancomycin. The van genes are organised into four transcription units, vanRS, vanJ, vanK and vanHAX, and these transcripts are induced by vancomycin in a vanR-dependent manner. vanHAX are orthologuous to genes found in vancomycin resistant enterococci that encode enzymes predicted to reprogramme peptidoglycan biosynthesis such that cell wall precursors terminate in D-Ala-D-Lac, rather than D-Ala-D-Ala. vanR and vanS encode a two-component signal transduction system that mediates transcriptional induction of the seven van genes. vanJ and vanK are novel genes that have no counterpart in previously characterised vancomycin-resistance clusters from pathogens. VanK is essential for vancomycin resistance in S. coelicolor and it is required for adding Gly branch to stem peptides terminating D-Ala-D-Lac. Because VanK can recognise D-Lac-containing precursors but the constitutively expressed femX enzyme, encoded elsewhere on the chromosome, cannot recognize D-Lac-containing precursors as a substrate, vancomycin-induced expression of VanHAX in a vanK mutant is lethal. Further, femX null mutants are viable in the presence of glycopeptide antibiotics but die in their absence. Bioassay using vanJp-neo fusion reporter system also showed that all identified inducers for van genes expression were glycopeptide antibiotics, but teicoplanin, a membrane-anchored glycopeptide, failed to act as an inducer.

• Journal of Veterinary Science
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• 제23권3호
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• pp.37.1-37.8
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• 2022

Background: Avian pathogenic Escherichia coli (APEC) causes colibacillosis, resulting in significant economic losses in the poultry industry. Objectives: In this study, the molecular characteristics of two extended-spectrum beta-lactamase (ESBL)-producing APEC isolates were compared with previously reported ESBL-producing E. coli isolates. Methods: The molecular characteristics of E. coli isolates and the genetic environments of the ESBL genes were investigated using whole genome sequencing. Results: The two ESBL-producing APEC were classified into the phylogenetic groups C and B1 and ST410 and ST162, respectively. Moreover, the ESBL genes of the two isolates were harbored in different Inc plasmids. The EC1809182 strain, harboring the bla_CTX-M-55 gene on the plasmid, exhibited extensive homology to IncFIB (98.4%) and IncFIC(FII) (95.8%). The EC1809191 strain, harboring the bla_CTX-M-1 gene, was homologous to IncI1-I (Gamma) (99.3%). All chromosomes carried the multidrug transporter, mdf(A) gene. Mobile genetic elements, adjacent to CTX-M genes, facilitated the dissemination of genes in the two isolates, analogous to other ESBL-producing E. coli isolates. Conclusions: This study clarifies the transmission dynamics of CTX-M genes and supports strengthened surveillance to prevent the transmission of the antimicrobial-resistant genes to humans via the food chain.

• 한국환경농학회지
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• 제41권4호
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• pp.335-343
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• 2022

BACKGROUND: Antibiotics used in animal husbandry for disease prevention and treatment have resulted in the rapid progression of antibiotic resistant bacteria which can be introduced into the environment through livestock feces/manure, disseminating antibiotic resistant genes (ARGs). In this study, fecal samples were collected from the livestock farms located in Jeju Island to investigate the relationship between microbial communities and ARGs. METHODS AND RESULTS: Illumina MiSeq sequencing was applied to characterize microbial communities within each fecal sample. Using quantitative PCR (qPCR), ten ARGs encoding tetracycline resistance (tetB, tetM), sulfonamide resistance (sul1, sul2), fluoroquinolone resistance (qnrD, qnrS), fluoroquinolone and aminoglycoside resistance (aac(6')-Ib), beta-lactam resistance (bla_TEM, bla_CTX-M), macrolide resistance (ermC), a class 1 integronsintegrase gene (intI1), and a class 2 integrons-integrase gene (intI2) were quantified. The results showed that Firmicutes and Bacteroidetes were dominant in human, cow, horse, and pig groups, while Firmicutes and Actinobacteria were dominant in chicken group. Among ARGs, tetM was detected with the highest number of copies, followed by sul1 and sul2. Most of the genera belonging to Firmicutes showed positive correlations with ARGs and integron genes. There were 97, 34, 31, 25, and 22 genera in chicken, cow, pig, human, and horse respectively which showed positive correlations with ARGs and integron genes. In network analysis, we identified diversity of microbial communities which correlated with ARGs and integron genes. CONCLUSION(S): In this study, antibiotic resistance patterns in human and livestock fecal samples were identified. The abundance of ARGs and integron genes detected in the samples were associated with the amount of antibiotics commonly used for human and livestocks. We found diverse microbial communities associated with antibiotics resistance genes in different hosts, suggesting that antibiotics resistance can disseminate across environments through various routes. Identifying the routes of ARG dissemination in the environment would be the first step to overcome the challenge of antibiotic resistance in the future.

• 한국육종학회지
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• 제41권3호
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• pp.244-251
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• 2009

벼흰잎마름병 저항성 유전자 Xa3을 침해하는 K3a 균계를 포함하여 24개의 균주에 대한 단일저항성 유전자와 2개 이상의 주동저항성 유전자가 결합된 계통에 대한 결과를 요약하면 다음과 같다. 1. 벼흰잎마름병 저항성 유전자 Xa3, Xa4, xa5 및 Xa7은 K1, K2, K3 균계에 저항성 반응을 보이며 K3a 균계에 대하여 Xa4는 중도저항성, xa5 및 Xa21은 저항성반응을 보였다. 2. 벼흰잎마름병 저항성 유전자 Xa3을 침해하는 24개 균주들에 대해 이병성을 보인 유전자는 Xa1, Xa2, xa8, Xa10, Xa11 및 xa13이었고, 저항성을 보인 유전자는 Xa4, xa5 및 Xa21이었다. Xa7 유전자는 반복친의 유전적 배경에 따라서 저항성 반응이 달랐다. 3. Xa4+xa5, Xa4+xa13, Xa4+Xa21, xa5+xa13, xa5+Xa21, xa13+Xa21, Xa4+xa5+xa13, Xa4+xa5+Xa21, Xa4+xa13+Xa21, xa5+xa13+Xa21, Xa4+xa5+xa13+Xa21 및 Xa3+xa5 등 2개 이상의 단일 주동 저항성 유전자가 결합되었을 때 K1, K2, K3 균계 및 Xa3 유전자를 침해하는 24개의 균주들에 강한 저항성 반응을 보였다. 4. Xa3 및 xa13 유전자는 24개의 균주들에 이병성을 보이지만 xa5, Xa4, Xa21 유전자와 결합되었을 때 단일저항성이 증가되었고, 중도저항성 반응을 보이는 Xa4 유전자는 xa5, Xa21 유전자와 결합되었을 때 고도의 저항성 반응을 보였다.