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Kim, Min Keun,Kang, Tae Ho,Kim, Sung Kyum,Jeong, Yu Seok,Yun, Han Dae,Kim, Hoon The Korean Society for Applied Biological Chemistr 2012 Applied Biological Chemistry (Appl Biol Chem) Vol.55 No.6
The rsmA gene was cloned from soft-rot bacterium Pectobacterium carotovorum subsp. carotovorum LY34 (Pcc LY34), and its role in pathogenicity was investigated by marker exchange mutagenesis. From a cosmid library of Pcc LY34 genomic DNA, a positive clone carrying the rsmA gene was selected, and the gene was cloned by polymerase chain reaction (PCR) amplification. The gene is 186 bp in size and encodes a protein of 62 amino acids with a predicted molecular mass of 6,839 Da. The calculated pI of the RsmA is 8.16. The phylogenetic tree showed that the RsmA of Pcc LY34 appeared genetically identical to the CsrA of Pectobacterium atrosepticum SCRI1043 (100% identity) and similar to the CsrA of Yersinia pestis KIM10+(98.3%). The gene was disrupted by the $Km^r$ gene, and the cells became mutated (i.e., $RsmA^-$ mutant). The pathogenicity test revealed that the disease rating of the $RsmA^-$ mutant only differed slightly from that of the wild type on a slice of potato tuber and a Chinese cabbage stalk. These results suggest that RsmA is not an essential factor for the pathogenicity of Pcc LY34 and that the rsmA gene of Pcc LY34 is not completely derepressed in the $RsmA^-$ mutant for virulence-related genes, contrary to the results of Erwinia carotovora subsp. carotovora $RsmA^-$ mutant, which proved hypervirulent for celery petioles. These results showed that the microenvironmental conditions of the host and/or strain of pathogen are important for the coordination of virulence gene expression.
Kim, Sang-Kyum,Kwen, Hai-Doo,Choi, Seong-Ho Pergamon 2012 Radiation physics and chemistry Vol.81 No.5
<P><B>Abstract</B></P><P>Vinyl copolymer–clay nanocomposites were prepared by γ-irradiation-initiated radical polymerization using a mixture of styrene (St) and divinyl benzene (DVB) in the presence of reactive organic montmorillonite clay (OMMT) in methanol at room temperature. Reactive OMMT was synthesized by a cation exchange reaction of Na<SUP>+</SUP>-MMT and 1-[(4-ethylphenyl)methyl]-3-butyl-imidazolium chloride as a reactive organic modifier in an aqueous solution. The microstructures of the nanocomposites were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal stability was examined by thermo gravimetric analysis (TGA). As a result, the reactive OMMT was a good additive material for preparing vinyl copolymer–clay nanocomposites.</P> <P><B>Highlights</B></P><P>► Vinyl copolymer–clay nanocomposites were prepared by γ-irradiation. ► Different St/DVB monomer ratios used to alter the crosslinking of the polymers. ► TEM revealed well exfoliated clay sheets dispersed in the ST/DVB copolymer matrix. ► More highly crosslinked copolymers formed as increasing DVB content.</P>
IRF7 promotes glioma cell invasion by inhibiting AGO2 expression.
Kim, Jun-Kyum,Jin, Xiong,Ham, Seok Won,Lee, Seon Yong,Seo, Sunyoung,Kim, Sung-Chan,Kim, Sung-Hak,Kim, Hyunggee Saikon Pub. Co 2015 TUMOR BIOLOGY Vol.36 No.7
<P>Interferon regulatory factor 7 (IRF7) is the master transcription factor that plays a pivotal role in the transcriptional activation of type I interferon genes in the inflammatory response. Our previous study revealed that IRF7 is an important regulator of tumor progression via the expression of inflammatory cytokines in glioma. Here, we report that IRF7 promotes glioma invasion and confers resistance to both chemotherapy and radiotherapy by inhibiting expression of argonaute 2 (AGO2), a regulator of microRNA biogenesis. We found that IRF7 and AGO2 expression levels were negatively correlated in patients with glioblastoma multiforme. Ectopic IRF7 expression led to a reduction in AGO2 expression, while depletion of IRF7 resulted in increased AGO2 expression in the LN-229 glioma cell line. In an in vitro invasion assay, IRF7 overexpression enhanced glioma cell invasion. Furthermore, reconstitution of AGO2 expression in IRF7-overexpressing cells led to decreased cell invasion, whereas the reduced invasion due to IRF7 depletion was rescued by AGO2 depletion. In addition, IRF7 induced chemoresistance and radioresistance of glioma cells by diminishing AGO2 expression. Finally, AGO2 depletion alone was sufficient to accelerate glioma cell invasion in vitro and in vivo, indicating that AGO2 regulates cancer cell invasion. Taken together, our results indicate that IRF7 promotes glioma cell invasion and both chemoresistance and radioresistance through AGO2 inhibition.</P>
A Chebyshev Collocation Method for Stiff Initial Value Problems and Its Stability
Kim, Sang-Dong,Kwon, Jong-Kyum,Piao, Xiangfan,Kim, Phil-Su Department of Mathematics 2011 Kyungpook mathematical journal Vol.51 No.4
The Chebyshev collocation method in [21] to solve stiff initial-value problems is generalized by using arbitrary degrees of interpolation polynomials and arbitrary collocation points. The convergence of this generalized Chebyshev collocation method is shown to be independent of the chosen collocation points. It is observed how the stability region does depend on collocation points. In particular, A-stability is shown by taking the mid points of nodes as collocation points.
Kim, Ock Tae,Cho, Sung Kyum Center for Asian Public Opinion ResearchCollaborat 2013 Asian journal for public opinion research Vol.1 No.1
The rise and fall of social research methods rely on how much a certain method is able to appropriately reflect the change of society. The present research proposes new mobile surveying methods, considering the current and future trends in Korea. In particular, this research focuses on environmental pressure (time constraints, the presence of others and the place) as one of the major factors influencing the effects of survey modes. For example, landline surveys are conducted in the respondent's home, which is a private and fixed space. On the other hand, surveys on mobile phones can be conducted in diverse places with other people around. After sampling 500 landline respondents and 500 mobile phone respondents using a quota method, the same questionnaire was used for both the mobile and landline interviews. The findings are generally consistent with the literature supporting the data quality and comparability of the mixed mode survey. These results are encouraging for researchers designing surveys that feature mobile phone data collection.