Dual Role of OhrR as a Repressor and an Activator in Response to Organic Hydroperoxides in Streptomyces coelicolor

Oh, So-Young,Shin, Jung-Ho,Roe, Jung-Hye American Society for Microbiology 2007 Journal of Bacteriology Vol.189 No.17

<B>ABSTRACT</B><P>Organic hydroperoxide resistance in bacteria is achieved primarily through reducing oxidized membrane lipids. The soil-inhabiting aerobic bacterium <I>Streptomyces coelicolor</I> contains three paralogous genes for organic hydroperoxide resistance: <I>ohrA</I>, <I>ohrB</I>, and <I>ohrC</I>. The <I>ohrA</I> gene is transcribed divergently from <I>ohrR</I>, which encodes a putative regulator of MarR family. Both the <I>ohrA</I> and <I>ohrR</I> genes were induced highly by various organic hydroperoxides. The <I>ohrA</I> gene was induced through removal of repression by OhrR, whereas the <I>ohrR</I> gene was induced through activation by OhrR. Reduced OhrR bound to the <I>ohrA-ohrR</I> intergenic region, which contains a central (primary) and two adjacent (secondary) inverted-repeat motifs that overlap with promoter elements. Organic peroxide decreased the binding affinity of OhrR for the primary site, with a concomitant decrease in cooperative binding to the adjacent secondary sites. The single cysteine C28 in OhrR was involved in sensing oxidants, as determined by substitution mutagenesis. The C28S mutant of OhrR bound to the intergenic region without any change in binding affinity in response to organic peroxides. These results lead us to propose a model for the dual action of OhrR as a repressor and an activator in <I>S. coelicolor</I>. Under reduced conditions, OhrR binds cooperatively to the intergenic region, repressing transcription from both genes. Upon oxidation, the binding affinity of OhrR decreases, with a concomitant loss of cooperative binding, which allows RNA polymerase to bind to both the <I>ohrA</I> and <I>ohrR</I> promoters. The loosely bound oxidized OhrR can further activate transcription from the <I>ohrR</I> promoter.</P>

석영과 장석의 Zeta 전위에 있어서 금속이온의 영향

오재현,박광원,이원해,원덕환 대한금속재료학회(대한금속학회) 1974 대한금속·재료학회지 Vol.12 No.4

石英과 長石의 活性化에 關한 資料를 얻기 爲해서 水溶液中 Mg^(++), Cu^(++), Zn^(++)과 Al^(+++)를 添加하여 鑛粒의 Zeta 電位를 測定하였다. 그리고 이들 鑛粒의 界面電氣現象과 金屬이온들의 加水分解特性을 서로 關聯시켜 比較 檢討하여 다음과 같은 結論을 얻었다. 1. 水溶液中에 金屬이온이 存在할 때 長石의 界面電氣現象은 石英과 같다. 2. 金屬이온種의 吸着으로 因해 石英과 長石의 界面은 陽(+)으로 荷電된다. 그리고 陽으로 荷電되는 pH 範圍는 金屬이온의 種類에 따라 다르다. 3. 水溶液中에 金屬이온들이 存在하면 鑛粒의 zpc(Zero point of charge)는 두 곳의 pH에서 나타난다. 두개의 zpc 중 하나의 zpc가 나타나는 pH는 M^(II)OH^+, M^(III)(OH)^+_2 및 M^(III)(OH)^(++) 이온種의 最高濃度가 나타나는 pH와 거의 一致한다. 마그네슘 이온의 경우에는 pH 10.1에서 단하나의 zpc가 나타난다. 4. Mg(II), Cu(II), Zn(II) 및 Al(III) 이온들의 加水分解特性과 zeta 電位를 關聯시켜 볼 때 Mg^(++), Cu^(++), Zn^(++) 및 Al^(+++)은 鑛粒表面에 對해 吸着力이 弱하고, 한편 M^(II)(OH)^+, M^(III)(OH)^+_2 및 M^(III)(OH)^(++) 이온種은 吸着力이 强함을 알 수 있다. To obtain a better understanding of quartz and orthoclase activation, zeta potentials of the minerals were studied in the presence of metallic ions such as Mg^(++), Cu^(++), Zn^(++) and Al^(+++). A microelectrophoresis technique has been used to measure the zeta potential, and the results have been correlated with the hydrolysis of the metallic ions in the solution. The experimental results have led to the following conclusions. 1. Zeta potentials of orthoclase in the presence of the metallic ions show a similar behavior to those of quartz. 2. Adsorption of the metallic ions renders the zeta potential of quartz and orthoclase positive. The pH range of positive zeta potential varies with the kind of cation. 3. Zero point of charge(ZPC) of the mineral surface in the presence of metallic ions appears at two different pH of solution. One of two pH of ZPC is consistent with the pH at which M^(II)(OH)^+ and M^(III)(OH)^+_2 or M^(III)(OH)^(++) species are predominant. 4. Comparison of the zeta potential data with the hydrolysis for Mg(II), Cu(II), Zn(II) and Al(III) species suggests that Mg^(++), Cu^(++), Zn^(++) and Al^(+++) are only weakly adsorbed at the mineral surface and that M^(II)(OH)^+ and M^(III)(OH)^+_2 or M^(III)(OH)^(++) are the main metallic ionic species adsorbed.

오지호 <남향집> 제작연도에 관한 실증적 연구

오병희(Oh Byung hee) 한국조형디자인학회 2017 조형디자인연구 Vol.20 No.2

<남향집>은 1930년대에 한국의 자연에 바탕을 둔 한국적 인상주의의 완성한 오지호의 대표작이다. 그리고 <남향집>은 오지호가 1935년부터 1944년까지 거주했던 개성 초당집의 사랑채와 앞뜰의 대추나무를 그린 작품으로 등록문화재로 지정되어 있다. 본 연구는 <남향집>이 1947년경 제작되고 1960년대 후반에 제작되거나 보필되었다는 연구에 관해 반론을 제시하였다. 각종 문헌과 아카이브 자료, 보고서를 근거로 <남향집>이 1939년 빛을 바탕으로 한국인의 정서를 담아 그린 근대미술작품임을 증명하였다. 또한 1948년 오지호 개인전에 사양(斜陽, 25호)으로 출품된 <남향집>에 관한 오지호의 작품 설명을 분석하여 작품을 제작한 계절과 시간, 작품 속 소녀에 관해 밝혀보았다. 이러한 연구를 통해 <남향집>이 1947년경 제작되고 1960년대 후반 재제작되었다는 주장에 대한 반증으로 작품에 대한 사실을 밝혀 보고자 하였다. 먼저 <남향집>이 일제강점기 개성 초당집 사진의 구도, 기물 등과 일치하지 않다는 주장에 관해 개성집 초당집 사진과 <남향집> 작품을 유족의 증언을 토대로 비교․분석하여 일치함을 증명하였다. 그리고 <남향집>의 소재가 전남 화순 동복의 오지호집이라는 주장에 대해 오지호 동복집은 기와집으로 기와집을 초가집으로 바꾸어 <남향집>을 그릴 수 없다는 근거를 제시하였다. 보존상태가 양호하여 해방 후 재제작 되었다거나 앞, 뒷면이 달라 보필하였다는 주장에 대해 1948년 오지호 개인전을 도운 김은수의 회상의 글을 근거로 당시 개성시기 현존하는 작품이 완벽한 상태였으며 1955년 오지호가 목조로 지은 작품 친화적인 오지호 화실을 통해 반증하였다. 그리고 국립현대미술관에서 2008년 오지호 작품 27점을 과학적 분석한 자료를 토대로 해방 후에 오지호가 작품을 덧칠하거나 재제작 했을 가능성이 희박함을 밝혔다. 본 연구의 <남향집>의 제작시기, 재료분석, 작품분석을 통해 한국적 인상주의를 완성한 오지호와 <남향집>에 관해 정당한 평가를 받을 수 있을 것이다. South Facing House is considered a seminal work by Oh Ji-ho who works in a kind of Korean-style Impressionism based on Korean nature. This painting features Sarangchae, a detached building of a residence used as a reception room for male guests, and a jujube tree in Chodangjip in Gaeseong where Oh resided from 1935 to 1944. This residence has been designated as a registered cultural property. This study raises an objection to an assertion that South Facing House was painted and complemented in 1947 or in the late 1960s. This study has verified that this work is a modern artwork painted in 1939 on the basis of literature, archived materials, and survey reports. It has also tried to elucidate the season and time of this painting and the girl appearing in this work based on the description of South Facing House that was on show at Oh’s 1948 solo exhibition under the title The Declining Sun. This has also verified the assertion that this work was not painted after Korea’s liberation from Japanese colonial rule. First of all, it has been proved that the setting of furniture and house hold items in South Facing House matches up with that of the photograph featuring Chodangjip through a comparative analysis on the basis of the bereaved family’s testimony. As to the assertion that South Facing House is a depiction of Oh’s house in Dongbok, Hwasoon, Jeonnam, this study provides evidence that the that thatched-roof house in South Facing House could not have been painted from the roof-tiled house in Dongbok. It has also proved its opposition against the assertion that this work was produced after liberation in consideration of its preservation and material, based on an essay by Kim Eun-soo who assisted at Oh’s 1948 solo exhibition. This study has revealed that the possibility of this work being repainted or reproduced by Oh after liberation is extremely low based on the materials of 27 pieces which the National Museum of Modern and Contemporary Art, Korea scientifically analyzed. A reasonable evaluation of Oh Ji-ho s Korean-style impressionism and his work South Facing House can be made through an analysis of the production period and materials.

Combustion characteristics of gaseous inverse O₂/H₂ coaxial jet flames in a single-element model combustor

Kim, Tae Young,Choi, Sun,Kim, Young Hoo,Ahn, Yeong Jong,Kim, Hee Kyung,Kwon, Oh Chae Elsevier 2018 ENERGY Vol.155 No.-

<P><B>Abstract</B></P> <P>To effectively design hydrogen (H<SUB>2</SUB>)/oxygen (O<SUB>2</SUB>) liquid rocket engines through understanding the combustion characteristics of H<SUB>2</SUB>/O<SUB>2</SUB> bipropellants, fundamental studies for the bipropellants in different phases are needed. This study is focused on the combustion characteristics of inverse gaseous O<SUB>2</SUB>/H<SUB>2</SUB> coaxial jet flames in a single-element model combustor as a preliminary step for succeeding studies of injection at different phases in the combustor, visualizing flame structure by direct imaging, OH<SUP>∗</SUP> chemiluminescence and OH planar laser-induced fluorescence. With increasing Reynolds number (Re), the frequency of occurrence of the local flame extinction increases and the length of the disconnected OH reaction zone is extended. The OH layer thickness increases downstream, while it is almost constant where the local flame extinction occurs and decreases with increasing Re due to the enhanced strain and scalar-dissipation rates. The excessive flame wrinkledness increases the local flame strain rate and results in the local flame extinction, exhibiting the tendency of increasing and then decreasing flame surface density with increasing Re. The probability density function of OH intensity quantifies the fluctuation intensity of OH radicals and the possibility of the local flame extinction. A useful database is provided for modeling the combustion of H<SUB>2</SUB>/O<SUB>2</SUB> bipropellants under different phases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A useful database for modeling the H<SUB>2</SUB>/O<SUB>2</SUB> bipropellant combustion is provided. </LI> <LI> Local flame extinction frequently occurs at high Reynolds number (<I>Re</I>). </LI> <LI> OH probability density function indicates the possibility of local extinction. </LI> <LI> Flame surface density increases and then decreases with increasing <I>Re</I>. </LI> <LI> Strong burning of O<SUB>2</SUB>/H<SUB>2</SUB> causes laminar-like combustion near the injector lip. </LI> </UL> </P>

정적 연소기내 혼합기 농도변화에 따른 OH분포 측정

최동석(D.S.Choi),김덕줄(D.J.Kim),오승묵(S.M.Oh),황의상(E.S.Hwang),정용일(Y.I.Jeong) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.6_2

The OH molecule is a highly reactive combustion intermediate and relatively abundant in combustion systems. It also has the availability of convenient UV -laser systems to excite the A²Σ-X²?? electronic transition. The spectroscopic parameters describing this transition are well known. In this research, the OH molecule was measured in the laminar flame burner and constant volume combustion chamber(CVCC) in order to use it as the fundamental data for studying combustion phenomena. The LIF images of the OH molecule in the laminar 리ame burner were caught by using KrF excimer laser and ICCD camera. The natural fluorescence<br/> of OH was also measured by the interference filter(310 nm) and spectrometer in the CVCC at different equivalence ratios.

전기차 배터리 냉각을 위한 3차원 진동형 히트파이프의 패턴에 따른 유동 가시화 연구

이지수 ( Ji-su Lee ),구본찬 ( Bon-chan Gu ),한진세 ( Jin-sae Han ),오인택 ( In-take Oh ),이석호 ( Seok-ho Rhi ) 충북대학교 산업과학기술연구소 2022 산업과학기술연구 논문집 Vol.36 No.2

Heat pipes using oscillating characteristics of vapor or liquid flow in a tube called an oscillating heat pipe (OHP) have been visualized and presented. Unlike ordinary planar type oscillating heat pipes, in the present study, 3-D oscillating heat pipes was designed, and tried to shape and verify the operability of upper heating OHP rather than lower heating OHP. Unlike the lower heating method, since the motion of the internal working fluid is directly affected by gravity, structural characteristics were studied to overcome gravity and create oscillation characteristics. In this study, it was observed that the supplied heat to the upper evaporator created the pressure difference as the internal space of the upper region was heated, and then eventually, internal working fluid was circulated by creating a pressure difference in the OHP, which was one of the anti-gravity heat pipes. It was observed that the internal working fluid is heated in the internal space of the upper part according to the heating in the evaporator, creating a pressure difference between the liquid and the lower part, and thus oscillating normally. In this study, the operating conditions of OHP using non-traditional heating and cooling modes were experimentally verified. Future electric vehicles are also suggested to use OHP in a few promising and innovative ways. The fundamental OHP operating mechanism for non-uniform working conditions are planned to be presented in this study.

기우제의(祈雨祭儀)를 통해 본 영남 지방관의 일상과 대민의식

오용원 ( Yong Won Oh ) 경북대학교 영남문화연구원 2009 嶺南學 Vol.0 No.16

Through this article, I investigated how Youngnam reeves performed ritual for rain as a official business. To do this I focused on the rituals of Chaewon Oh Hoing-Mook (1834~?), who was reeve of Youngnam province. Oh`s ritual was official, but dynamic and flexible. In a aspect Oh`s ritual for rain was one of his routine jobs. In other aspect, through his ritual, Oh tried to establish social integration with consideration for the subjects. The ritual for rain was performed when drought kept going on. In this natural crisis. he held the ceremony to meet the subjects face by face. Through two additional ritual, especially, he preserved social order, and took care of the subjects preferentially. All social class people can also meet each other in the ritual. Performing the ritual with highly established form, he also gave great concern to the subjects. He gained sympathy of the subjects`s pain, and paid fruits or money. He also minimized the subjects`s burden loaded to them. In these his routine rituals, I can know that reeves shared their joy with the subjects and communicated each other. It is fundamental procedure to choose ritual place, to prepare things needed in the ceremony, and to write a ritual oration in the official ritual. It is common to prepare ritual place, things needed in ritual, and order of ritual according to law books. The ritual was based on Conficianism, therefore taboos or belief system of official ceremony was less restricted than those of private ceremony. One of remarkable thing is ritual oration. After 13th ritual, the two additional rituals was executed. In those rituals, the formality of orations were less strict than that of previous 13 rituals. He showed his wish for raining with the ritual oration, which had long sentences and flexible contents. Reeves usually understood the Mother Nature in aspect of Confucianism. Eventually, reeves recognized the relationship between God and human as a reciprocal interaction.

Role of LuxIR Homologue AnoIR in Acinetobacter nosocomialis and the Effect of Virstatin on the Expression of anoR Gene

( Man Hwan Oh ),( Chul Hee Choi ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.8

Quorum sensing is a process of cell-to-cell communication in which bacteria produce autoinducers as signaling molecules to sense cell density and coordinate gene expression. In the present study, a LuxI-type synthase, AnoI, and a LuxR-type regulator, AnoR, were identified in Acinetobacter nosocomialis, an important nosocomial pathogen, by sequence analysis of the bacterial genome. We found that N-(3-hydroxy-dodecanoyl)-L-homoserine lactone (OH-dDHL) is a quorum-sensing signal in A. nosocomialis. The anoI gene deletion was responsible for the impairment in the production of OH-dDHL. The expression of anoI was almost abolished in the anoR mutant. These results indicate that AnoI is essential for the production of OH-dDHL in A. nosocomialis, and its expression is positively regulated by AnoR. Moreover, the anoR mutant exhibited deficiency in biofilm formation. In particular, motility of the anoR mutant was consistently and significantly abolished compared with that of the wild type. The deficiency in the biofilm formation and motility of the anoR mutant was significantly restored by a functional anoR, indicating that AnoR plays important roles in the biofilm formation and motility. Furthermore, the present study showed that virstatin exerts its effects on the reduction of biofilm formation and motility by inhibiting the expression of anoR. Consequently, the combined results suggest that AnoIR is a quorum-sensing system that plays important roles in the biofilm formation and motility of A. nosocomialis, and virstatin is an inhibitor of the expression of anoR.

Equaatiorial-Skew [Co(TRDTRA)(OH₂)] 착물과 CN, NO₂그리고 NCS 이온간의 치환반응

都命基,趙榮在,李東鎭,吳昌彦,金東曄 嶺南大學校 基礎科學硏究所 1992 基礎科學硏究 Vol.12 No.-

Equatorial-Skew형[Co(TRDTRA)(OH₂)]착물과 ??,?? 그리고 ?? 이온 간의 치환반응결과 생성된 차물의 치환반응성 및 구조를 전자흡수 스펙트럼과 Yamatera 이론에 따라 조사하였다. 속도론적 자료로부터 착물과 ??,?? 그리고 ?? 이온의 반응차수는 각각 1차이며 총괄 반응차수는 2차임을 알 수 있었다. ?? 및 ?? 이온에서 생성된 착물의 구조는 이성질화 반응이 동반된 Polar-Chair 형이며, ?? 이온의 경우에는 이성질화 반응이 동반되지 않은 Equatorial-Skew 형임을 알 수 있었다. The substitution reaction and structrue of products obtained from the reaction of Equatorial-Skew-[Co(TRDTRA)(OH??)](TRDTRA=trimethylenediaminetriacetate) with ??,??, and NCS ions have been investigated by means of electronic absorption spectroscopy and theoretical calculation based on the Yamatera`s theory. According to kinetic data, the substitution reaction order for the complexes such as ??,?? and ?? was the first order, respectively, and overall reaction order was second order. It has been determined that the structure of products having ?? and ?? ions was Polar-Chair type complexes which were accompanying with isomerization and having ?? ion was Equatorial-Skew type complex which was not accompanying with isomerization.

모델연소실 내 GCH₄/GO₂ 및 GH₂ /GO₂ 동축류 제트화염의 연소특성 기초 연구

최선(Sun Choi),김태영(Tae Young Kim),김희경(Hee Kyung Kim),권오채(Oh Chae Kwon) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12

로켓 엔진의 차세대 액체이원추진제로서 각광을 받고 있는 메탄(CH₄)/산소(O₂) 이원추진제의 기초연소특성 및 연소 안정화의 고유특성 확인을 위해 수소(H2)/산소 이원추진제 연소특성과 비교 연구를 수행하였다. 기초 연소특성 연구를 위한 모델연소실 내에서 기체 메탄(GCH₄)/기체 산소(GO₂) 및 기체수소(GH₂)/GO₂의 동축류 제트화염의 연소안정한계와 직접 사진, OH<SUP>*</SUP> 자발광 이미지를 측정한 결과, GCH₄/GO₂와 GH₂/GO₂ 모두 산소-연료 모멘텀비((O/F)mom)가 감소함에 따라 연소안정한계는 확장되는 경향을 보였으나 GH₂/GO₂ 화염에 비해 GCH₄/GO₂ 화염은 좁은 연소안정한계가 측정되었고, 또한 GCH₄/GO₂ 화염은 이론당량비 조건에서, GH2/GO₂ 화염은 연료과농 조건에서 최대 OH* 강도가 측정됨을 OH<SUP>*</SUP> 자발광 가시화를 통해 확인하였다. Liquid methane (CH₄)/oxygen (O₂) bipropellants have been recently considered as a next-generation propellant due to eco-friendly and non-toxic properties, low cost and high performance. To investigate the unique features of CH₄/O₂ bipropellants, the fundamental combustion characteristics of gaseous CH₄/O₂ and H₂/O₂ coaxial jet flames in a model combustor are investigated through measuring the combustion stability limits and visualizing flames. Results show that the combustion stability limits of GCH₄/GO₂ flames are reduced compared with the GH₂/GO₂ flames. The maximum OH<SUP>*</SUP> intensity of GCH₄/GO₂ flames is observed at near-stoichiometric condition, while the GH₂/GO₂ flames at fuel-rich condition.