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Transcriptional Analysis of the iagB within Salmonella Pathogenicity Island 1 (SPI1)
Lim, Sangyong,Choi, Jihae,Kim, Dongho,Seo, Ho Seong The Korean Society for Microbiology 2016 Journal of Bacteriology and Virology Vol.46 No.3
HilA is a central regulator of Salmonella pathogenicity island 1 (SPI1), which is necessary for host invasion by Salmonella and induction of gastroenteritis. The iagB lies downstream of hilA and is thought to be co-transcribed with hilA, but iagB expression has not yet been analyzed directly. In this study, iagB expression in various mutant strains was measured to determine whether the expression pattern was similar to that of hilA. A ${\beta}$-galactosidase assay revealed that iagB expression was greater under shaking than standing culture condition. iagB expression was decreased in relA/spoT and ihfB mutants but not in luxS mutant, in line with previous reports on hilA expression. The hilA and iagB mRNA levels decreased by approximately 2-fold in arcA mutant grown aerobically and increased by approximately 10-fold in fnr mutant grown anaerobically. Although the fold changes in hilA and iagB mRNA level differed in hfq mutant strain, the patterns of time- and Hfq-dependent regulation were similar for both genes. Thus, iagB and hilA exhibited similar expression patterns in various mutational backgrounds and under different growth condition.
Antioxidant activities of fucoidan degraded by gamma irradiation and acidic hydrolysis
Lim, Sangyong,Choi, Jong-il,Park, Hyun Pergamon 2015 Radiation physics and chemistry Vol.109 No.-
<P><B>Abstract</B></P> <P>Low molecular weight fucoidan, prepared by radical degradation using gamma ray was investigated for its antioxidant activities with different assay methods. As the molecular weight of fucoidan decreased with a higher absorbed dose, ferric-reducing antioxidant power values increased, but <I>β</I>-carotene bleaching inhibition did not change significantly. The antioxidant activity of acid-degraded fucoidan was also examined to investigate the effect of different degradation methods. At the same molecular weight, fucoidan degraded by gamma irradiation showed higher 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity than that observed with the acidic method. This result reveals that in addition to molecular weight, the degradation method affects the antioxidant activity of fucoidan.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Antioxidant activity of fucoidan degraded by gamma-irradiation was analyzed. </LI> <LI> Degree of change of antioxidant activity was dependent on the measuring method. </LI> <LI> Acid hydrolyzed fucoidan was compared to gamma-irradiated for its antioxidant activity. </LI> </UL> </P>
Lim, Sangyong,Yun, Jiae,Yoon, Hyunjin,Park, Chehwee,Kim, Boowon,Jeon, Byeonghwa,Kim, Dongho,Ryu, Sangryeol Oxford University Press 2007 Nucleic acids research Vol.35 No.6
<P>The global regulator Mlc is a repressor of several genes and operons that are involved in sugar uptake and metabolism. A <I>Salmonella enterica</I> serovar Typhimurium <I>mlc</I> mutant showed reduced levels of invasion and cytotoxicity compared to the wild-type, and exhibited reduced expression levels of <I>hilD</I>, <I>hilA</I> and <I>invF</I>, which are regulatory genes in the <I>Salmonella</I> pathogenicity island 1 (SPI1). However, the effects of Mlc on <I>hilD</I> expression and bacterial invasiveness were not seen in the <I>hilE</I> mutant, and <I>hilE</I> expression was increased in the <I>mlc</I> mutant, which suggests that Mlc exerts positive effects on the expression of SPI1 genes by reducing the expression of HilE, which is known to down-regulate the expression of SPI1 genes through direct interaction with HilD. We found that the two known promoters of <I>hilE</I> were not modulated by Mlc, and we identified a third promoter, designated P3, which was repressed by Mlc. The gel mobility shift assay and footprinting analysis revealed that Mlc repressed <I>hilE</I> in a direct manner by binding to two distinct sites in the <I>hilE</I> P3 promoter region. The specific down-regulation of <I>hilD</I> observed in the presence of Mlc regulon-inducible sugars, such as glucose and mannose, could not be detected in the <I>mlc</I> mutant. Based on these results, we propose that Mlc functions to sense the availability of sugars and is linked to virulence gene regulation by its ability to control <I>hilE</I> expression in <I>Salmonella</I>.</P>
Lim, Sangyong,Choi, Jihae,Kim, Minjeong,Yoon, Hyunjin The Korean Society for Applied Biological Chemistr 2015 Applied Biological Chemistry (Appl Biol Chem) Vol.58 No.2
Hfq is a global regulatory RNA-binding protein abundant in many bacteria. In terms of virulence regulation in Salmonella, Hfq binds to and stabilizes them RNA of hilD, a master regulator of Salmonella pathogenicity island 1 (SPI-1), and Hfq activates SPI-1 gene transcription during the late exponential-growth phase. In contrast to the positive roles of Hfq in SPI-1 regulation, we observed that the absence of Hfq increased the expression of SPI-1 regulators, including HilA and InvF, during the late stationary phase. This result suggests that Hfq has pleiotropic functions, controlling SPI-1 positively or negatively depending on the growth conditions.
Lim, Sangyong,Yoon, Hyunjin,Ryu, Sangryeol,Jung, Jinwoo,Lee, Myungchul,Kim, Dongho Academic Press 2006 Radiation research Vol.165 No.4
Lim, S., Yoon, H., Ryu, S., Jung, J., Lee, M. and Kim, D. A Comparative Evaluation of Radiation-Induced DNA Damage using Real-Time PCR: Influence of Base Composition. Radiat. Res. 165, 430??437 (2006).To study the radiosensitivity of DNA segments at the open reading frame (gene) level, real-time PCR was used to analyze DNA damages induced by ionizing radiation. After irradiation (1, 3 and 5 kGy) of genomic DNA purified from Salmonella typhimurium, real-time PCR based on SYBR Green fluorescence and melting temperature was performed using various primer sets targeting the rfbJ, rfaJ, rfaB, hilD, ssrB, pipB, sopD, pduQ, eutG, oadB, ccmB and ccmA genes. The ccmA and ccmB genes, which existed as two copies on the chromosome and had a high GC content (??0%), showed much lower radiosensitivities than the other genes tested, particularly at 5 kGy; this distinctive feature was seen only when the genes were located on the chromosome, regardless of copy number. Our results reinforce the concept that gene sensitivity to ionizing radiation depends on the base composition and/or the spatial localization of the gene on the chromosome.
이상용(Sangyong Lee),강봉완(Bongwan Kang),김성춘(Seongchun Kim),고재진(Jaejin Ko),최종수(Jongsoo Choi),김중기(Junggi Kim),임준기(Jungi Lim) 한국철도학회 2016 한국철도학회 학술발표대회논문집 Vol.2016 No.5
서울도시철도 구간에는 ATC(Automatic Train Control) 신호시스템으로 구성되어, 자동운전이 가능할 뿐만 아니라 돌발상황 시에는 관제에서 비상정지 함으로써, 전동차 운행을 중지시킬 수 있어 안전과도 밀접한 관련이 있다. 그러나 불연속적인 신호가 발생될 때에는 무신호로 인식하여 원활한 전동차의 운행을 방해하는 요인이 되기도 한다. 본 논문에서는 2015년전동차에 탑재가 가능한 7호선용 ATC 자체개발 측정기를 활용하여 실제 운행 중에 수집된 ATC 신호데이터를 정밀 분석하여, 궤도와 궤도 사이의 신호의 크기 및 속도코드 변경 시 ATC 신호의 변화를 분석하고, 이 분석데이터를 활용하여 열차 안전운행을 위한 ATC 신호 관리방안을 제시하고자 한다. There is ATC(Automatic Train Control) signal in urban railway at Seoul Metropolitan Rapid Transit, which enables not only to have trains be moved automatically, but also to have trains stop forcibly by disconnecting it in case of emergency. That is why the ATC signal is important and related with safety. However, a discontinuous signal of ATC causes trains not to be operated appropriately. Therefore, this study is going to describe the management plan of ATC signal for the safe operation of trains and stability of the system by analyzing the data obtained with the device, which was developed with our own technology for line 7 at 2015, on a train while it is operating, and examining the amplitude of the signal among tracks and the variations of ATC signal as speed code changes.