http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Choi, Byoung-Ju,Lee, Jung A,Choi, Jae-Sung,Park, Jong-Gyu,Lee, Sang-Ho,Yih, Wonho Pergamon Press 2017 Chemosphere Vol.173 No.-
<P><B>Abstract</B></P> <P>Hydrographic observation and biological samplings were conducted to assess the distribution of phytoplankton community over the sloping shelf of the eastern Yellow Sea in May 2012. The concentration of chlorophyll <I>a</I> was determined and phytoplankton was microscopically examined to conduct quantitative and cluster analyses. A cluster analysis of the phytoplankton species and abundance along four observation lines revealed the three-dimensional structure of the phytoplankton community distribution: the coastal group in the mixed region, the offshore upper layer group preferring stable water column, and the offshore lower layer group. The subsurface maximum of phytoplankton abundance and chlorophyll <I>a</I> concentration appeared as far as 64 km away from the tidal front through the middle layer intrusion. The phytoplankton abundance was high in the shore side of tidal front during the spring tide. The phytoplankton abundance was relatively high at 10-m depth in the mixed region while the concentration of chlorophyll <I>a</I> was high below the depth. The disparity between the profiles of the phytoplankton abundance and the chlorophyll <I>a</I> concentration in the mixed region was related to the depth-dependent species change accompanied by size-fraction of the phytoplankton community.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Physical environment, chlorophyll concentration and phytoplankton community were investigated in the eastern Yellow Sea. </LI> <LI> Three-dimensional structure of phytoplankton communities was identified in the tidal front region. </LI> <LI> Phytoplankton abundance and chlorophyll <I>a</I> concentration were high in the shore side of the front during the spring tide. </LI> <LI> Subsurface maximum of phytoplankton abundance appeared about 64 km away from the front through the middle layer intrusion. </LI> <LI> Profiles of phytoplankton abundance and chlorophyll <I>a</I> concentration were different due to depth-dependent species change. </LI> </UL> </P>
Translation-dependent mRNA cleavage by YhaV in <i>Escherichia coli</i>
Choi, Wonho,Yamaguchi, Yoshihiro,Lee, Jae-Woo,Jang, Kyung-Min,Inouye, Masayori,Kim, Sung-Gun,Yoon, Min-Ho,Park, Jung-Ho North-Holland Pub 2017 FEBS letters Vol. No.
<P>Many bacteria have toxin-antitoxin (TA) systems, where toxin gene expression inhibits their own cell growth. mRNA is one of the well-known targets of the toxins in the type II toxin-antitoxin systems. Here, we examined the ribosome dependency of the endoribonuclease activity of YhaV, one of the toxins in type II TA systems, on mRNA in vitro and in vivo. A polysome profiling assay revealed that YhaV is bound to the 70S ribosomes and 50S ribosomal subunits. Moreover, we found that while YhaV cleaves ompF and lpp mRNAs in a translation-dependent manner, they did not cleave the 5' untranslated region in primer extension experiments. From these results, we conclude that YhaV is a ribosome-dependent toxin that cleaves mRNA in a translation-dependent manner.</P>
( Wonho Choi ),( Min-ho Yoon ),( Jung-ho Park ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.6
Bacterial programmed cell death is regulated by the toxin-antitoxin (TA) system. YhaV (toxin) and Pr1F (antitoxin) have been recently identified as a type II TA system in Escherichia coli. YhaV homologs have conserved active residues within the C-terminus, and to characterize the function of this region, we purified native YhaV protein (without denaturing) and constructed YhaV proteins of varying lengths. Here, we report a new low-temperature method of purifying native YhaV, which is notable given the existing challenges of purifying this highly toxic protein. The secondary structures and thermostability of the purified native protein were characterized and no significant structural destruction was observed, suggesting that the observed inhibition of cell growth in vivo was not the result of structural protein damage. However, it has been reported that excessive levels of protein expression may result in protein misfolding and changes in cell growth and mRNA stability. To exclude this possibility, we used an [<sup>35</sup>S]-methionine prokaryotic cell-free protein synthesis system in vitro in the presence of purified YhaV, and two C-terminal truncated forms of this protein (YhaV-L and YhaV-S). Our results suggest that the YhaV C-terminal region is essential for mRNA interferase activity, and the W143 or H154 residues may play an analogous role to Y87 of RelE.
Choi Wonho,Maharjan Anoth,Im Hae Gang,Park Ji-Young,Park Jong-Tae,Park Jung-Ho 한국미생물학회 2023 The journal of microbiology Vol.61 No.4
Toxin-antitoxin (TA) systems are widespread in bacteria and archaea plasmids and genomes to regulate DNA replication, gene transcription, or protein translation. Higher eukaryotic and prokaryotic nucleotide-binding (HEPN) and minimal nucleotidyltransferase (MNT) domains are prevalent in prokaryotic genomes and constitute TA pairs. However, three gene pairs (MTH304/305, 408/409, and 463/464) of Methanothermobacter thermautotropicus ΔH HEPN-MNT family have not been studied as TA systems. Among these candidates, our study characterizes the MTH463/MTH464 TA system. MTH463 expression inhibited Escherichia coli growth, whereas MTH464 did not and blocked MTH463 instead. Using site-directed MTH463 mutagenesis, we determined that amino acids R99G, H104A, and Y106A from the R[ɸX]4-6H motif are involved with MTH463 cell toxicity. Furthermore, we established that purified MTH463 could degrade MS2 phage RNA, whereas purified MTH464 neutralized MTH463 activity in vitro. Our results indicate that the endonuclease toxin MTH463 (encoding a HEPN domain) and its cognate antitoxin MTH464 (encoding the MNT domain) may act as a type II TA system in M. thermautotropicus ΔH. This study provides initial and essential information studying TA system functions, primarily archaea HEPN-MNT family.
Choi Wonho,Kim Jae-hui,Lee Ju Seok,Park Jung-Ho 대한독성 유전단백체 학회 2023 Molecular & cellular toxicology Vol.19 No.3
Backgrounds Almost all bacteria harbor toxin–antitoxin (TA) systems on their chromosomes, which are associated with diverse biological roles such as stress response, cell physiology, biofi lm formation, and programmed cell death. Pseudomonas cichorii JBC1 has a diverse host range and can cause disease in a wide range of plant species. Under favorable environmental conditions, the bacterium can cause severe disease in nearly all of the crops that have been described. However, TA systems have not been determined. Objective This study aimed to identify the TA system of P. cichorii JBC1 genome based on the cell toxicity of Escherichia coli regulated by TA systems and to evaluate the mRNA expression levels under various stressful growth conditions. Results Among 11 putative TA pairs predicted from the P. cichorii JBC1 genome by in silico analysis, two toxins, PCH70- 01,410 and − 16,540, caused cell growth arrest and cell death in E. coli , and the toxicity of PCH70-01,410 and − 16,540 was neutralized by its cognate antitoxin candidates, PCH70-01,400 and − 16,550 in PCH70-01,400/01410 and PCH70- 16,550/16540 TA complexes, respectively. Moreover, mRNA expression levels of PCH70-01,400/01410 and PCH70- 16,550/16540 diff ered under various stresses (i.e., oxidative, acidic, and heat shocks). Conclusion Two TA systems, PCH70-01,400/01410 and PCH70-16,550/16540, were identifi ed in P. cichorii JBC 1. These TA systems show diff erent toxin and antitoxin mRNA expression levels according to stressful growth conditions, including oxidative, acidic, and heat shocks in E. coli .
ICT 활용 지리수업을 위한 DB형 교수-학습 자료 개발
신기진(Wonhoe Choi),백종렬(Namkang Cho),현경숙(Kilsoo Jang),신홍철(Jongseung Park),구기남(Kyuhak Choi),노충덕(Kijin Shin),최원회(Jongryol Baek),조남강(Gyeongsuk Hyun),장길수(Hongcheol Shin),박종승(Kinam Koo),최규학(Chungdug Rho) 대한지리학회 2003 대한지리학회지 Vol.38 No.2
ICT(Information & Communication Technology) 활용 지리수업을 위해서는 데이터베이스(database, 이하,‘DB’라 칭함)형 교수-학습 자료를 개발하는 것이 필수적이다. 이러한 DB형 교수-학습자료는 WBI(Web Based<br/> Instruction, 웹기반수업)에서의 지리이미지자료 사용상의 문제점을 극복해 줄 대안으로 간주된다. 이를 위하여 본 연구에서는 우선 지리이미지 데이터베이스 프로그램(이하,‘지리이미지 DB 프로그램’이라 칭함)을 기반으로 CD-ROM 형태의 지리이미지 전자사전(이하,‘GEO-DB’라 칭함)을 제작했다. GEO-DB에는 3,060개의 지리이미지가 원자료로 수록되어 있는데, 이러한 자료들은 온라인과 오프라인 상에서 교사와 학습자가 공동으로 수집한 것이다. GEO-DB에는 교사와 학습자 모두 지리이미지 자료를 단순하게 활용함은 물론, 임의적으로 자료의 가공이 가능하도록 포트폴리오 기능을 첨부했는데, 이러한 포트폴리오 기능은, 특히 학습자의 자기주도적 학습능력의 신장에 기여하고자 한 것이다. GEO-DB는 사용의 수월성, 검색의 신속성 및 확장의 무한성을 갖고 있어서, 지리 교수-학습에서 ICT의 활용 가능성을 극대화시켜 줄 수 있고, 학습자의 지리학습능력의 신장과 지리학습태도의 변화에 크게 기여할 수 있는 것으로 교사와 학습자에 의해 평가되었다. It was essential to develop the DB-type teaching and learning material for geography instruction using a method of ICT. The DB-type teaching and learning material was considered as a alternative in solving the problems of web-based geography instruction. Accordingly, in this study, the geography image DB program was developed, and based on this program the CD-ROM called GEO-DB, having the function of electronic dictionary of geography image for geography teaching and learning was made. The GEO-DB was composed of 3,060 geography images collected by teachers and learners. The GEO-DB was made to be used simply by teachers and learners. Especially, the portfolio function was included in the GEO-DB, and that was focused to the instructional system design of teacher and the self-directed learning ability development of learner. Teachers<br/> and learners using this GEO-DB assessed that because the GEO-DB had the easiness of use, the speed of reference and the unlimitedness of extension, it could enlarge the possibility of using a method of ICT, and it could contribute to the development of geography learning ability and the change of geography learning attitude.