• Molecules and Cells
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• v.42 no.12
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• pp.850-857
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• 2019

The Gram-negative opportunistic pathogen, Pseudomonas aeruginosa, has multiple multidrug efflux pumps. MexT, a LysR-type transcriptional regulator, functions as a transcriptional activator of the MexEF-OprN efflux system. MexT consists of an N-terminal DNA-binding domain and a C-terminal regulatory domain (RD). Little is known regarding MexT ligands and its mechanism of activation. We elucidated the crystal structure of the MexT RD at 2.0 Å resolution. The structure comprised two protomer chains in a dimeric arrangement. MexT possessed an arginine-rich region and a hydrophobic patch lined by a variable loop, both of which are putative ligand-binding sites. The three-dimensional structure of MexT provided clues to the interacting ligand structure. A DNase I footprinting assay of full-length MexT identified two MexT-binding sequence in the mexEF-oprN promoter. Our findings enhance the understanding of the regulation of MexT-dependent activation of efflux pumps.

• BMB Reports
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• v.47 no.4
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• pp.203-208
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• 2014

To gain insights into the effect of MexB gene under the short interfering RNA (siRNA), we synthesized 21 bp siRNA duplexes against the MexB gene. RT-PCR was performed to determine whether the siRNA inhibited the expression of MexB mRNA. Changes in antibiotic susceptibility in response to siRNA were measured by the E-test method. The efficacy of siRNAs was determined in a murine model of chronic P. aeruginosa lung infection. MexB-siRNAs inhibited both mRNA expression and the activity of P. aeruginosa in vitro. In vivo, siRNA was effective in reducing the bacterial load in the model of chronic lung infection and the P. aeruginosa-induced pathological changes. MexB-siRNA treatment enhanced the production of inflammatory cytokines in the early infection stage (P < 0.05). Our results suggest that targeting of MexB with siRNA appears to be a novel strategy for treating P. aeruginosa infections.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.492-495
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• 2015

This study provides evidence that RecG regulates the expression of the OxyR-independent gene mexA in Pseudomonas aeruginosa PAO1. A reduction in mexA expression was observed in the absence of RecG, but not OxyR, by northern blot and quantitative real-time PCR analyses. The canonical palindromic RecG binding sequence was present upstream of the mexA promoter, and bound purified RecG and single strand-binding protein. These data reveal a novel mechanism of OxyR-independent gene transcription by RecG.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.9-21
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• 2005

To study the biochemical and physiological role of the plastidic glucose transporter (pGlcT) in carbohydrate metabolism, we characterized transgenic plants with mutations in the pGlcT gene (GT), gt-1 and gt-2, as well double mutants of GT and the maltose transporter (MEX1) and GT and the triose phosphate/phosphate translocator (TPT), GT and the cytosolic fructose-1,6-bisphosphatase gene (cFBP), and MEX1 and TPT, gt-1/mex2, gt-1/tpt-2, gt-1/cfbp-1, mex1-1/tpt-2, respectively. Compared to the wild type, all mutants except the gt-1/cfbp-1 mutant lines displayed higher starch accumulation and higher levels of maltose. Starch accumulation is due to a decrease in starch turnover, leading to an imbalance between the rates of synthesis and degradation. Sucrose levels of gt alleles were higher than those in wild-type plants during the light period, suggesting possible nightly supplementation via the maltose transport pathway to maintain proper carbohydrate partitioning in the plant leaves. The gt plants displayed less growth retardation than mex1-1 mutant and gt-1/mex2 double mutant displayed accumulativesevere growth retardation as compared to individual gt-1 and mex1-1 mutants, implying that the maltose transporter-mediated pathway is a major route for carbohydrate partitioning at night. The gt-1/tpt-2, mex1-1/tpt-2 and gt-1/cfbp-1 double mutants had retarded growth and low chlorophyll content to differing degrees, indicating that photosynthetic capacity had diminished. Interestingly, the gt-1/tpt-2 line displayed a glucose-insensitive phenotype and higher germination rates than wild type, suggesting its involvement not only in carbon partitioning, but also in the sugar signaling network of the pGlcT and TPT.

• Communications of the Korean Mathematical Society
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• v.11 no.4
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• pp.1031-1046
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• 1996

The purpose of this paper is to investigate a necessary and sufficient condition for submanifold of $MEX_n$ to be einstein and to derive the generalized fundamental equations on the submanifold of $MEX_n$.

• Bulletin of the Korean Mathematical Society
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• v.40 no.3
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• pp.475-487
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• 2003

A generalized even-dimensional Riemannian manifold defined by the ME-connection which is both Einstein and of the form (3.3) is called an even-dimensional ME-manifold and we denote it by $MEX_{2n}$. The purpose of this paper is to study a necessary and sufficient condition that there is an ME-connection, to derive the useful properties of some tensors, and to investigate a representation of the ME-vector in $MEX_{2n}$.

• Journal of the Chungcheong Mathematical Society
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• v.23 no.3
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• pp.495-510
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• 2010

An Einstein's connection which takes the form (2.23) is called a $^*g$-ME-connection and the corresponding vector is called a $^*g$-ME-vector. The $^*g$-ME-manifold is a generalized n-dimensional Riemannian manifold $X_n$ on which the differential geometric structure is imposed by the unified field tensor $^*g^{{\lambda}{\nu}}$, satisfying certain conditions, through the $^*g$-ME-connection and we denote it by $^*g-MEX_n$. The purpose of this paper is to derive a general representation and a special representation of the $^*g$-ME-vector in $^*g-MEX_n$.

• Honam Mathematical Journal
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• v.30 no.4
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• pp.603-616
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• 2008

A generalized n-dimensional Riemannian manifold $X_n$ on which the differential geometric structure is imposed by the unified field tensor $^*g^{{\lambda}{\nu}}$, satisfying certain conditions, through the $^*g$-ME-connection which is both Einstein's equation and of the form(3.1) is called $^*g$-ME-manifold and we denote it by $^*g-MEX_n$. In this paper, we prove a necessary and sufficient condition for the existence of $^*g$-ME-connection and derive a surveyable tensorial representation of the $^*g$-ME-connection and the $^*g$-ME-vector in $^*g-MEX_n$.

• Explosives and Blasting
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• v.22 no.1
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• pp.15-22
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• 2004

일반적으로 석회석 광산에서의 발파는 ANFO를 사용하여 주로 시행되어지고 있다. Bulk장전 시스템의 도입으로 장약, 발파가 간편하여 효과적으로 발파를 할 수 있고 그 비용도 저렴하다는 장점을 가지고 있다. 그러나 수공에서의 장약이 불가능하고 낮은 위력으로 인해 저항선 및 공간격의 제한이 커서 이에 따르는 발파효율의 저하가 불가피 하였다. 본 연구는 현재 해외에서 일반화되어 사용되고 있는 Bulk EMX(HiMEX)폭약을 국내 현장에 적용함으로 그 적용 방법과 이점을 규명하고자 시행되었다. 대규모 석회석 광산을 대상으로 적정 패턴을 산출하기 위해 기존의 발파 패턴과 비교하여 시험발파를 시행하여 저항선 및 공간격을 산정 하였으며 이를 토대로 해서 성신양회, 현대시멘트 영월사업소와 함께 장기간 시험발파를 실시하고 그 자료를 검증하였다. 그 결과 HiMEX는 초유폭약에 비해 비중이 높아 공당 장약량은 45%정도 증가하나, 1발파 당 생산 물량이 증가하여 5%이상의 장약량 감소효과를 볼 수 있었다. 또한 35∼50%정도의 천공비용이 감소되는 것으로 나타났다.

• Horticultural Science & Technology
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• v.30 no.2
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• pp.185-191
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• 2012

For initiation of resistance breeding program of the red pepper, 21 PR ($Phytophthora$ resistance) cultivars, 36 cultivars collected from USA and 'Supermanitta' which is a susceptible cultivar against phytophthora blight were assayed against phytophthora blight, powdery mildew, and anthracnose. For seedling assay of phytophthora blight, three different mating type strains of $Phytophthora$ $capsici$ were used (A1, A2, Sterile). The result showed that most of the pepper of PR cultivars were resistance or moderately resistance at each mating type. 'Yeokganghongjanggun' was resistant to all three $P.$ $capsici$ strains and 'PR-Datta' and 'PR-Manitta' were resistant or moderately resistant at each type. In case of the collected cultivars, 'NuMex J.E.Parker', 'Omni Color', and 'SCM334' were resistant to all the three types and some cultivars including 'Sweet Banana' and 'Tabasco' were moderately resistant to each type fungi. 'Orange Habanero' and 'Black Cuban' were resistant to powdery mildew and 'Supermanitta' and 'PR Keumdong' were moderately resistant, while 'Santa Fe Grande', 'NuMex Pinata' and 'Puya' were very susceptible. In the case of anthracnose, 'Aji Limon' and 'Capsicum baccatum var. pendulum 3-4' were resistant and 'Pobalno', 'Omni Color', 'Negro', 'Mesilla', 'Mulato', 'Bhut Jolokia', 'Big Dipper', 'Black Cuban', 'NuMex Pinata', and 'NuMex Big Jim' were moderately resistant. The most PR cultivars except 'Taesan' were susceptible or very susceptible. These resistant individuals identified through this experiment can be used as sources of resistance to pepper pathogens in the future breeding programs.