• 제목/요약/키워드: hilC

검색결과 21건 처리시간 0.023초

Salmonella Invasion Gene Regulation: A Story of Environmental Awareness

  • Jones Bradley D.
    • Journal of Microbiology
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    • 제43권spc1호
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    • pp.110-117
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    • 2005
  • Salmonella enterica serovar Typhimurium causes human gastroenteritis and a systemic typhoid-like infection in mice. A critical virulence determinant of Salmonella is the ability to invade mammalian cells. The expression of genes required for invasion is tightly regulated by environmental conditions and a variety of regulatory genes. The hilA regulator encodes an OmpR/ToxR family transcriptional regulator that activates the expression of invasion genes in response to both environmental and genetic regulatory factors. Work from several laboratories has highlighted that regulation of hilA expression is a key point for controlling expression of the invasive phenotype. A number of positive regulators of hilA expression have been identified including csrAB, sirA/barA, pstS, hilC/sirC/sprA, fis, and hilD. HilD, an AraC/XylS type transcriptional regulator, is of particular importance as a mutation in hilD results in a 14-fold decrease in chromosomal hilA::Tn5lacZY-080 expression and a 53-fold decrease in invasion of HEp-2 cells. It is believed that HilD directly regulates hilA expression as it has been shown to bind to hilA promoter sequences. In addition, our research group, and others, have identified genes (hilE, hha, pag, and lon) that negatively affect hilA transcription. HilE appears to be an important Salmonella-specific regulator that plays a critical role in inactivating hilA expression. Recent work in our lab has been directed at understanding how environmental signals that affect hilA expression may be processed through a hilE pathway to modulate expression of hilA and the invasive phenotype. The current understanding of this complex regulatory system is reviewed.

Analysis of Salmonella Pathogenicity Island 1 Expression in Response to the Changes of Osmolarity

  • LIM, SANG-YONG;YONG, KYEONG-HWA;RYU, SANG-RYEOL
    • Journal of Microbiology and Biotechnology
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    • 제15권1호
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    • pp.175-182
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    • 2005
  • Abstract Salmonella pathogenicity island 1 (SPI1) gene expression is regulated by many environmental signals such as oxygen, osmolarity, and pH. Here, we examined changes in the expression level of various regulatory proteins encoded within SPI1 in response to three different concentrations of NaCl, using primer extension analysis. Transcription of all the regulatory genes tested was activated most when Salmonella were grown in Luria Broth (LB) containing 0.17 M NaCl. The expression of hilA, invF, and hilD was decreased in the presence of 0.47 M NaCl or in the absence of NaCl, while hilC expression was almost constant regardless of the NaCl concentration when Salmonella were grown to exponential phase under low-oxygen condition. The reduced expression of hilA, invF, and hilD resulted in lower invasion of hilC mutant to the cultured animal cells when the mutant was grown in the presence of 0.47 M NaCl or in the absence of NaCl prior to infection. Among the proteins secreted via the SPI1-type III secretion system (TTSS), the level of sopE2 expression was not influenced by medium osmolarity. Various effects of osmolarity on virulence gene regulation observed in this study is one example of multiple regulatory pathways used by Salmonella to cause infection.

정공주입층에 따른 OLED 소자의 발광 특성 (Emission Properties of OLED Devices with Various Hole Injection Materials)

  • 이봉섭;고신위;박종억;백용구;양재웅;백경갑;주성후
    • 한국전기전자재료학회논문지
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    • 제21권6호
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    • pp.562-568
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    • 2008
  • In this paper, the hole injection layer(HIL) materials have been synthesized and analyzed. Their HOMO levels are $4.93{\sim}5.22\;eV$, and their energy band gaps are $2.74{\sim}3.19\;eV$. Their glass transition temperatures($T_g$) are all above $114^{\circ}C$, which implies that they are highly thermal-stable. The green OLED devices with a structure of ITO(150 nm)/NEW_HIL(50 nm)/NPB(30 nm)/$Alq_3$(50 nm)/Al:Li(100 nm) were fabricated and tested, incorporating these newly synthesized HIL materials. According to the test results of OLED devices, the I-V-L performances of these devices increase in the following sequence: ELM307 > ELM200 > ELM321 > ELM327 > ELM325. In addition, the OLED device with ELM307 as a HIL has the highest brightness and efficiency at the same driving voltage. These experimental results have shown that ELM307 can be used as one of the most promising candidates for HIL materials.

Effects of Sulforaphane, Grapefruit Seed Extracts, and Reuterin on Virulence Gene Expression Using hilA and invF Fusion Strains of Salmonella typhimurium

  • Kim, Ji-Yeun;Ryu, Sang-Ryul;Ji, Geun-Eog
    • Food Science and Biotechnology
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    • 제16권5호
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    • pp.778-782
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    • 2007
  • This study assessed the effects of the antimicrobial substances sulforaphane, grapefruit seed extracts (GSE), and reuterin on the expression of Salmonella HilA and InvF virulence gene using a LacZY assay (${\beta}$-galactosidase assay) with hilA:lacZY and invF:lacZY fusion strains of Salmonella typhimurium SL1344. Salmonella was grown for 8 hr at $37^{\circ}C$ in the presence of diluted antimicrobial substances ($2\;{\mu}g/mL$ sulforaphane, $20\{\mu}g/mL$ GSE, and 0.26 mM reuterin) at concentrations that did not inhibit the cellular growth of Salmonella. Sulforaphane inhibited the expression of HilA and InvF by 50-90 and 20-80%, respectively. GSE also inhibited the expression of both genes, but to a lesser degree. Among the 3 antimicrobial substances, reuterin showed the least inhibition, which was abolished after 3-4 hr. None of the antimicrobial substances inhibited the ${\beta}$-galactosidase enzyme activity of S. typhimurium. The assay used in this study represents a very sensitive method for screening bioactive substances that inhibit the expression of virulence genes in Salmonella.

Hfq and ArcA Are Involved in the Stationary Phase-Dependent Activation of Salmonella Pathogenicity Island 1 (SPI1) Under Shaking Culture Conditions

  • Lim, Sangyong;Yoon, Hyunjin;Kim, Minjeong;Han, Ahreum;Choi, Jihae;Choi, Jeongjoon;Ryu, Sangryeol
    • Journal of Microbiology and Biotechnology
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    • 제23권12호
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    • pp.1664-1672
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    • 2013
  • In Salmonella enterica serovar Typhimurium, many genes encoded within Salmonella pathogenicity island 1 (SPI1) are required to induce intestinal/diarrheal disease. In this study, we compared the expression of four SPI1 genes (hilA, invF, prgH, and sipC) under shaking and standing culture conditions and found that the expression of these genes was highest during the transition from the exponential to stationary phase under shaking conditions. To identify regulators associated with the stationary phase-dependent activation of SPI1, the effects of selected regulatory genes, including relA/spoT (ppGpp), luxS, ihfB, hfq, and arcA, on the expression of hilA and invF were compared under shaking conditions. Mutations in the hfq and arcA genes caused a reduction in hilA and invF expression (more than 2-fold) in the early stationary phase only, whereas the lack of ppGpp and IHF decreased hilA and invF gene expression during the entire stationary phase. We also found that hfq and arcA mutations caused a reduction of hilD expression upon entry into the stationary phase under shaking culture conditions. Taken together, these results suggest that Hfq and ArcA regulate the hilD promoter, causing an accumulation of HilD, which can trigger a stationary phase-dependent activation of SPI1 genes under shaking culture conditions.

100종 브라질 식물 추출물로부터 반추동물 산독증 예방치료를 위한 $\alpha$-amylase 및 $\alpha$-glucosidase 저해제의 선별 (Screening of $\alpha$-amylase and $\alpha$-glucosidase Inhibitors from Brazilian Plant Extracts for Treatment of Rumen Acidosis)

  • 김미선;안선미;정인창;권기석;손호용
    • 한국식품저장유통학회지
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    • 제17권2호
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    • pp.290-296
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    • 2010
  • 반추동물의 급성 산독증의 예방 및 치료제 개발을 위해 100종의 브라질 식물 추출물을 이용하여 미생물 유래의 $\alpha$-amylase 및 $\alpha$-glucosidase 저해 활성을 평가하였다. 그 결과 Acacia jurema Mart., Anacardium humile A. St.-Hil., Cedrela odorata L., 및 Guazuma ulmifolia Lam 추출물에서 우수한 $\alpha$-amylase 및 $\alpha$-glucosidase 저해 활성을 확인하였으며, Plumeria drastica Mart.에서는 우수한 $\alpha$-amylase 특이적 저해활성을, Eugenia uniflora L.에서는 강력한 $\alpha$-glucosidase 특이적 저해 활성을 확인하였다. 6종의 추출물을 대상으로 $\alpha$-amylase에 대한 $IC_{50}$ 평가 결과, 현지에서 항당뇨제로 사용되는 A. humile A. St.-Hil., 추출물($IC_{50}$: $91.2{\mu}g/ml$)이 가장 강력한 저해를 나타내었으며, 항당뇨제로 이용되고 있는 acarbose ($IC_{50}$:$50.5{\mu}g/mL$)의 저해활성에 필적하였다. A. humile A. St.-Hil., 추출물은 $80^{\circ}C$, 또는 0.01N HCl 조건에서 60분간 처리에 활성의 변화가 나타나지 않았으며, 산 처리시에는 오히려 활성의 증가가 나타났다. 또한 A. humile A. St.-Hil., 추출물은 인간 적혈구에 대한 용혈활성을 나타내지 않아 반추동물의 급성 산독증 및 인간 당뇨병 치료에도 이용 가능하리라 판단된다.

Phenyl-Naphthyl Amine Effect of New Phenothiazine Derivatives with High Tg for Hole Injection and Hole Transporting Materials

  • Kim, Soo-Kang;Lee, Ji-Hoon;Park, Jong-Wook
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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    • pp.450-453
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    • 2008
  • We synthesized a new HIL and HTL materials by using phenothiazinly moiety, 1,4-diphenothiazyl-benzene [DPtzB], 3',7',3",7"-tetrakis(N-phenyl-2-naphthylamine)-1,4-diphenothiazyl-benzene[PNA-DPtzB]. Synthesized materials exhibited high Tg in the range of $175\;-\;202^{\circ}C$. These values are much better than commonly used hole transporting materials (2-TNATA and NPB). The OLED device that used DPtzB as a HIL showed the highest efficiency of 4.31cd/A at $10mA/cm^2$.

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HYBRID ROLL CONTROL USING ELECTRIC ARC SYSTEM CONSIDERING LIMITED BANDWIDTH OF ACTUATING MODULE

  • Kim, H.J.;Lee, C.R.
    • International Journal of Automotive Technology
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    • 제3권3호
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    • pp.123-128
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    • 2002
  • This paper presents the design of an active roll control system for a ground vehicle and an experimental study using an devised electric-actuating roll control system. Based on a three degree of freedom linear vehicle model, the controller is designed using lateral acceleration and rollrate feedback. In order to investigate the feasibility of an active control system, experimental work is carried out using a hardware-in-the-loop (Hil) setup which has been constructed by the devised electric-actuating system and the full vehicle model including tire characteristics. The performance is evaluated by an experiment using the Hil setup with limited bandwidth. Finally, in order to enhance the control performance in the transient region, a hybrid control strategy is proposed and evaluated.

Genetic and Environmental Control of Salmonella Invasion

  • Altier, Craig
    • Journal of Microbiology
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    • 제43권spc1호
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    • pp.85-92
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    • 2005
  • An early step in the pathogenesis of non-typhoidal Salmonella species is the ability to penetrate the intestinal epithelial monolayer. This process of cell invasion requires the production and transport of secreted effector proteins by a type III secretion apparatus encoded in Salmonella pathogenicity island I (SPI-1). The control of invasion involves a number of genetic regulators and environmental stimuli in complex relationships. SPI-1 itself encodes several transcriptional regulators (HilA, HilD, HilC, and InvF) with overlapping sets of target genes. These regulators are, in turn, controlled by both positive and regulators outside SPI-1, including the two-component regulators BarA/SirA and PhoP/Q, and the csr post-transcriptional control system. Additionally, several environmental conditions are known to regulate invasion, including pH, osmolarity, oxygen tension, bile, $Mg^{2+}$ concentration, and short chain fatty acids. This review will discuss the current understanding of invasion control, with emphasis on the interaction of environmental factors with genetic regulators that leads to productive infection.

PEDOT-PSS/NPD-$C_{60}$ 정공 주입/수송 층이 도입된 유기발광소자의 성능 향상 연구 (Enhanced Efficiency of Organic Electroluminescence Diode Using PEDOT-PSS/NPD-$C_{60}$ Hole Injection/Transport Layers)

  • 박경남;강학수;나타라잔 센틸루마르;박대원;최영선
    • 폴리머
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    • 제33권5호
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    • pp.407-412
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    • 2009
  • 유기발광소자(OLED)에서 정공 수송층(hole injection layer, HIL)으로 사용되는 N,N'-di-1-naphthyl-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPD)가 정공 주입층(hole injection layer HIL)으로 사용된 PEDOT-PSS 층 위로 진공 증착되었다. PEDOT-PSS 층은 ITO 유리 위에 스핀 코팅되어 제조되었다. 또한, NPD와 $C_{60}$의 공증착에 의해 $C_{60}$이 약 10 wt% 도핑된 NPD-$C_{60}$ 층을 제조하였으며, AFM과 XRD를 이용하여 NPD-$C_{60}$ 박막의 모폴로지 특성을 관찰하였다. 다층 소자를 제조하여 J-Y, L-V 및 전류 효율 특성이 고찰되었다. $C_{60}$박막은 국부적인 결정성 구조를 가지고 있으나, NPD-$C_{60}$ 박막에서는 $C_{60}$ 분자가 균일하게 분산되어 $C_{60}$의 결정성 구조가 확인되지 않았다. 또한, $C_{60}$의 도핑에 의해서 박막의 표면이 균일해지는 것을 확인하였으며, 박막 내의 전류 밀도가 증가됨을 확인하였다. NPD-$C_{60}$ 박막을 이용하여 ITO/PEDOT-PSS/NPD-$C_{60}/Alq_3$/LiF/Al 다층 소자를 제조하였을 때, 소자의 휘도 측면에서 약 80% 향상 효과가 있었으며, 소자 효율 측면에서도 약 25%의 향상을 기대할 수 있었다.