• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.521-529
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• 2016

Extensive use of antibiotics over recent decades has led to bacterial resistance against antibiotics, including gentamicin, one of the most effective aminoglycosides. The emergence of resistance is problematic for hospitals, since gentamicin is an important broad-spectrum antibiotic for the control of bacterial pathogens in the clinic. Previous study to identify gentamicin resistance genes from environmental samples have been conducted using culture-dependent screening methods. To overcome these limitations, we employed a metagenome-based culture-independent protocol to identify gentamicin resistance genes. Through functional screening of metagenome libraries derived from soil samples, a fosmid clone was selected as it conferred strong gentamicin resistance. To identify a specific functioning gene conferring gentamicin resistance from a selected fosmid clone (35-40 kb), a shot-gun library was constructed and four shot-gun clones (2-3 kb) were selected. Further characterization of these clones revealed that they contained sequences similar to that of the RNA ligase, T4 rnlA that is known as a toxin gene. The overexpression of the rnlA-like gene in Escherichia coli increased gentamicin resistance, indicating that this toxin gene modulates this trait. The results of our metagenome library analysis suggest that the rnlA-like gene may represent a new class of gentamicin resistance genes in pathogenic bacteria. In addition, we demonstrate that the soil metagenome can provide an important resource for the identification of antibiotic resistance genes, which are valuable molecular targets in efforts to overcome antibiotic resistance.

• 한국식품영양학회지
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• 제9권4호
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• pp.459-465
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• 1996

지금까지 많은 연구가 되어 있지 않던 Bacillus thuringiensis serovar. darmstadiensis의 내독소를 Renografin-76 단계적 기울기 원심분리로 분리하여 전자 현미경으로 관찰하여 이중피라미드 구조를 가진 독소 단백질을 확인하였으며 B. thuringiensis serovar. kurstaki HD1의 독소 생성유전자와 B. thuringiensis serovar. darmstadiensis의 유전자가 유사성이 있다는 보고를 근거로 하여 B. thuringiensis serovar. HD1의 독소 생성유전자를 가진 프로브(pUYBT 9044)로 이용하여 colony hybridization 및 Southern hybridization 한 결과 2.6Kb EcoRI 단편 및 3.6Kb Hind III 단편을 선발할 수 있었다. 이들 단편들은 B. thuringiensis serovar. kurstaki HD1 독소 유전자와 hybridization시 유사성이 있었다. 특히 3.5Kb HindIII 단편은 2.6Kb EcoR I 단편에 클로닝되어 있는 1.8Kb의 HD1 독소 유전자와 유사성이 있는 부분을 공유하고 있었으며 1.0Kb 정도의 EcoR I-HindIII 부분이 더 삽입한 것을 알 수 있었다.

• 한국미생물·생명공학회지
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• 제16권5호
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• pp.389-392
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• 1988

Escheriachia coli pSL 2-1 clone은 Bacillus sphaericus 1593의 모기살충 유전자를 클로닝한 재조합 DNA이다. 이 클론이 생산하는 살충독소 단백질의 분자량을 SDS-polyacrylamide gel을 이용하여 측정했다. B. sphaericus 1593균이 생산하는 독소결정체를 분리하여 전기영동을 한 결과는 6개의 단백질밴드(43, 58, 64, 100, 113, 130Kd)가 형성되었으나, 독소결정체를 알칼리 pH로 용해하여 전기영동을 하면 2개의 단백질 밴드(43과 64Kd)만이 나타났다. 그러나 대장균 pSL2-1균이 생산하는 독소단백질을 Sephadex G-200으로 정제하여 모기유충에 살충력이 있는 단백질을 전기영동한 결과는 42Kd만이 나타났다. LC50은 2 $\mu\textrm{g}$/$m\ell$이었다. B. sphaericus와 pSL2-1 clone 생산하는 살충단백질은 42Kd 단백질인 것으로 생각된다.

• Journal of Microbiology
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• 제45권5호
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• pp.447-452
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• 2007

In this study, we compared the phenotypic and genotypic characteristics of 138 MRSA isolates obtained from adult and pediatric patients (adult, 50; children, 88). The resistance rates against gentamicin, clindamycin, and ciprofloxacin were much higher in the adult MRSA isolates than in the pediatric MRSA isolates. The ermC gene, which is responsible for inducible clindamycin resistance, was detected in 52(59.1%) of the 88 pediatric MRSA isolates but in only 5(10.0%) of the 50 adult MRSA isolates. MRSA isolates of clonal type ST5 with an integration of SCCmec type II/II variants was the most predominant clone among the adult isolates, while clonal type ST72 with an integration of SCCmec IV/IVA was the most predominant clone among the pediatric MRSA isolates. Staphylococcal enterotoxin A and toxic shock syndrome toxin-1 were prevalent among the adult MRSA isolates but not among the pediatric MRSA isolates. The results of this study demonstrated remarkable differences between adult and pediatric MRSA isolates in terms of their antimicrobial susceptibility profiles, SCCmec type, multilocus sequence type, staphylococcal toxin genes, and erythromycin resistance genes.

• 미생물학회지
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• 제29권2호
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• pp.75-79
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• 1991

The yeast L-A virus (4.6 kb dsRNA genome) encodes the major coat protein and a "gag-pol" fusion minor coat protein that separately encapsidate itself and $M_{1}$, a 1.8 kb dsRNA satellite virus encoding a secreted protein toxin (the killer toxin). The teast chromosomal SKI genes prevent viral cytopathology by lowering the virus copy number. Thus, $ski^{-}$ mutants are ts and cs for growth. We transformed a ski2-2 virus-infested mutant with a yeast bank in a high copy cloning vector and selected the rare healthy transformants for analysis. One type of transformant segregated M-O L-A-O cells with high frequency. Elimination of the DNA clone from the ski2-2 strain eliminated this phinotype and introduction of the DNA clone recovered from such transformants into the parent ski2-2 strain, or into ski3 or ski6 mutants gave the same phenotype. This killer-curing phenotype was due to the curing of the helper L-A dsRNA virus. The 6.5 kb insert only had this activity when carried on a high copy vector and in $ski^{-}$ cells (not in $SKI^{+}$ cells). This 6.5 kb insert acts as a mutagen on L-A dsRNA producing a high rate of deletion mutations.mutations.

• KSBB Journal
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• 제6권3호
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• pp.289-297
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• 1991

The insecticidal protein gene in the pKL-20-1 clone derived from Bacillus thuringiensis serovar. kurstaki plasmid was subcloned in the plant shuttle vector, pGA643. The 7.3 kb fragment was cloned in the BglII and Hpal sites of pGA643 vector and expressed in E. coli S17-1, which produced insecticidal proteins killing Bombyx mori larvae. The clone was named pHL-20. The protoplast formation, calli induction and plantlet regeneration of Nicotiana tabacum was carried out. A tremendous number of mesophyll protoplasts of N. tabacum were formed, up to 7$\times$105 protoplast per ml, for 20 hours in darkness in the enzyme solution of 0.5% cellulase and 0.1% macerosin, pH 5.8. The viabilities of the protoplasts were maintained above 80% for 6 days in the media containing 2mg/1 of NAA and 1mg/1 of kinetin. Calli were induced from the protoplasts and leaves of the N. tabacum on MS medium containing 0.5mg/1 BAP. Under the culture conditions the protoplasts underwent repeated cell division into calli. Plantlets were regenerated from callus cultures derived from protoplast and leaves. Shoots were induced in a medium containing 1mg/1 of BAP.

• 한국잠사학회:학술대회논문집
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• 한국잠사학회 2003년도 International Symposium of Silkworm/Insect Biotechnology and Annual Meeting of Korea Society of Sericultural Science
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• pp.114-115
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• 2003

A Bacillus thuringiensis isolate, Bt 2385-1, which showed toxicity to lepidopteran, was isolated from Korean soil sample and characterized. PCR-RFLP showed that this isolate contains two novel cryl-type crystal protein genes. In this study, we designed cryl-type specific primer set (ATG1-F and N400-R) to clone the toxic domain of the all cryl-type genes. The two novel rlyl-type toxin genes in addition to crylJal gene were cloned and sequenced. (omitted)

• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.1093-1098
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• 2001

The gene coding for a Lepidoptera-specific insecticidal crystalline (or control) protein (ICP), recognized as cryIAc, from Bacillus thuringiensis subsp. kurstaki HD-73, was cloned into the vector pBluscript ll SK-, and then transformed in Escherichia coli $DH5{\alpha}$. The clone was named EBtIAc and the chimeric phagemid, as pEBtIAc. Hyperexpression of CryIAc protoxin was observed in the extract of the culture of E. coli harboring pEBtIAc. Crystalline protoxin was purified by differential solubility. It was dissolved in alkaline pH, and exposed to trypsin to be activated. The molecular weights of the pro- and activated toxins on SDS-PAGE were estimated to be ca. 130 kDa and 60 kDa, respectively. The toxicity was tested by force-feeding larvae of gypsi moth (Lymantria diapar) with trypsinized protoxin. Using the batch of biologically active form of the toxin as an immunogen, anti-CryIAc antiserum was raised in a New Zealand white rabbit. Immunoglobulin G was fractionated from the seam by Protein-A sepharose affinity chromatography. Immunoreactivity of the antibody was examined by dot and Westerns blottings. It has been found that the anti- CryIAc antibody recognized the purified toxin at a level below a nanogram in terms of quantity. Using the antibody some of Bt-corns were able to be differentiated from tons of corn kernels which were imported from America as forage crops.

• 한국발생생물학회:학술대회논문집
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• 한국발생생물학회 2003년도 제3회 국제심포지움 및 학술대회
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• pp.86-86
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• 2003

Research has been in progress for more than a decade to production of useful proteins by genetic modification in cattle. However, the levels of protein production in transgenic cattle have been reported very low. To enhance protein production in transgenic animal, we tried homologous recombination to donor cells for production of transgenic clone cattle through nuclear transfer procedure. Thus, we constructed the two targeting vectors of human thrombopoietin (TPO) at bovine $\beta$-casein locus using homologous recombination with 13.6 kb and 9.6 kb homology. In two targeting vectors, positive selection was through the neomycin resistance gene and negative selection was by the diphtheria toxin (DT). Gene targeting was attempted in bovine embryonic fibroblasts (bEF) and bovine ear skin fibroblasts (bESF). To determine the most appropriate concentration of neomycin for bEF and bESF, G4l8 resistance was confirmed by culturing the cells in various concentrations of the drug and both of the cells were optimally selected at $900 \mu g/ml$ of neomycin. The transfected bEF and bESF by the targeting vectors were colonized efficiently at the ratio of DNA to transfection reagent such as $4 \mu g$:2 ${mu}ell$ and $1 \mu g$:$2 \mu l$. Comparing number of healthy clones from passage 4 to passage 8, bESF (17%) persist in culture for much longer than bEF (6%). The two gene-targeted bESF clones of 30 random-integrated clones with 9.6 kb homology length were confirmed, however, nothing was out of 72 random integration clones with 13.6 kb homology length, The DT also worked more efficiently in clones transfected with the vector of 9.6 kb homology length. Our data suggests that the choice of donor cell for long culture period should be considered to obtain targeted cell clone, and the gene-targeting frequency and the DT working efficiency are dependent on the length of target homology.

• Journal of Plant Biotechnology
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• 제37권3호
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• pp.313-318
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• 2010

돼지 흉막폐렴백신을 개발하기 위해 옥수수 HiII genotype 으로부터 유도한 type II형의 배발생캘러스를 식물발현벡터 pMYV611, pMYV613, pMYV616, V621, V622 및 V623로 형질전환시킨 Agrobacterium (C58C1)과 공동배양 하였다. 이들 식물발현벡터는 paromomycin 항생제 저항 유전자인 NPTII 선발마커와 표적 유전자로서 흉막폐렴균의 여러 가지 혈청을 생산하는 apxIIA유전자로 재조합하여 구축하였다. 식물발현벡터pMYV611, pMYV613, pMYV616, V621, V622 및V623의 경우 각각 4,120개, 5,959개, 7,581개, 52,329개, 48,948개 및 56,188개의 캘러스 클론을 Agrobacterium과 공동한 후 NPTII assay kit에 의해 nptII유전자의 발현빈도를 조사한 결과 각 벡터별로 2.3-4.4%의 캘러스 클론에서 항체결합 양성반응을 보였고, 이들 중 최종적으로 선발된 형질전환 캘러스 클론은 pMYV611에서 3개 (0.07%), pMYV613에서 4개 (0.07%), pMYV616에서 2개 (0.02%), V621에서 51개 (0.1%), V622에서 72개 (0.15%) 및 V623에서 102개 (0.18%)를 각각 얻었다. 형질전환된 캘러스 클론으로부터 재분화된 식물체에서 유전자 도입여부를 Southern 분석으로 통해 확인한 결과 pMYV613에서 2개 식물체 및 V623에서 얻은 2개 식물체에서 각각 확인되었다.