• BMB Reports
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• 제47권11호
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• pp.609-618
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• 2014

DNA methylation at cytosines (5mC) is a major epigenetic modification involved in the regulation of multiple biological processes in mammals. How methylation is reversed was until recently poorly understood. The family of dioxygenases commonly known as Ten-eleven translocation (Tet) proteins are responsible for the oxidation of 5mC into three new forms, 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). Current models link Tet-mediated 5mC oxidation with active DNA demethylation. The higher oxidation products (5fC and 5caC) are recognized and excised by the DNA glycosylase TDG via the base excision repair pathway. Like DNA methyltransferases, Tet enzymes are important for embryonic development. We will examine the mechanism and biological significance of Tet-mediated 5mC oxidation in the context of pronuclear DNA demethylation in mouse early embryos. In contrast to its role in active demethylation in the germ cells and early embryo, a number of lines of evidence suggest that the intragenic 5hmC present in brain may act as a stable mark instead. This short review explores mechanistic aspects of TET oxidation activity, the impact Tet enzymes have on epigenome organization and their contribution to the regulation of early embryonic and neuronal development.

• 한국가축번식학회지
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• 제27권4호
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• pp.309-315
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• 2003

DNA methylation at CpG sites, which is a epigenetic modification, is associated with gene expression without change of DNA sequences. During early mouse embryogenesis, dynamic changes of DNA methylation occur. In this study, DNA methylation patterns of porcine embryos produced in vivo and in vitro were examined at various developmental stages by the immunocytochemical staining method. Interestingly, active demethylation was not observed on the paternal pronucleus of porcine zygotes. However, differences were detected in the passive demethylation process between in vivo and in vitro embryos. There was no change in the DNA methylation state until the blastocyst stage of in vivo embryos, whereas partial demethylation was observed in several blastomeres from a 4 cell stage to a morula stage of in vitro embryos. The whole genome of inner cell mass (ICM) and trophectoderm (TE) cells in porcine blastocysts were evenly methylated without de novo methylation. Our findings demonstrate that genome-wide demethylation does not occur in pig embryos during preimplantation development unlike murine and bovine embryos. It indicates that the machinery regulating epigenetic reprogramming may be different between species.

• 약학회지
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• 제37권1호
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• pp.95-99
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• 1993

Peroxidase activity of cytochrome P-450 was examined using N, N-dimethylaniline (NDA) as a substrate and cumene hydroperoxide (CHP) as an oxidant. The initial rates of the N-demethylation for varied concentrations of NDA (0.05-0.5 mM) by P-450 at different fixed concentrations of CHP (0.02-0.2 mM) were determined. The results suggest that P-450 proceeds its peroxidative reaction by the rapid equilibrium random bi bi mechanism to form a ternary complex with substrate and oxidant as an active intermediate.

• The Plant Pathology Journal
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• 제36권6호
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• pp.579-590
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• 2020

Botrytis cinerea, which causes gray mold disease in more than 200 plant species, is an economically important pathogen that is mainly controlled by synthetic fungicides. Synergistic fungicide mixtures can help reduce fungicide residues in the environment and mitigate the development of fungicide-resistant strains. In this study, we screened microbial culture extracts on Botrytis cinerea to identify an antifungal synergist for tebuconazole. Among the 4,006 microbial extracts screened in this study, the culture extract from Schizophyllum commune displayed the most enhanced activity with a sub-lethal dosage of tebuconazole, and the active ingredient was identified as schizostatin. In combination with 5 ㎍/ml tebuconazole, schizostatin (1 ㎍/ml) showed disease control efficacy against gray mold on tomato leaf similar to that achieved with 20 ㎍/ml tebuconazole treatment alone. Interestingly, schizostatin showed demethylation inhibitor (DMI)-specific synergistic interactions in the crossed-paper strip assay using commercial fungicides. In a checkerboard assay with schizostatin and DMIs, the fractional inhibitory concentration values were 0.0938-0.375. To assess the molecular mechanisms underlying this synergism, the transcription levels of the ergosterol biosynthetic genes were observed in response to DMIs, schizostatin, and their mixtures. Treatment with DMIs increased the erg11 (the target gene of DMI fungicides) expression level 15.4-56.6-fold. However, treatment with a mixture of schizostatin and DMIs evidently reverted erg11 transcription levels to the pre-DMI treatment levels. These results show the potential of schizostatin as a natural antifungal synergist that can reduce the dose of DMIs applied in the field without compromising the disease control efficacy of the fungicides.

• 한국발생생물학회:학술대회논문집
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• 한국발생생물학회 2003년도 제3회 국제심포지움 및 학술대회
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• pp.26-28
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• 2003

"Epigenetics" means the study of heritable changes in gene-activity without changes in DNA sequences. Methylation of the cytosine residue in a CpG dinucleotide sequence is a characteristic of the vertebrate genome. In vertebrates, methylation of DNA mainly occurs at the 5′-position of cytosine in a CpG dinucleotide forming 5-methylcytosine. Methylation of DNA plays a profound role in transcriptional repression of gene expression through several mechanisms. Generally, DNA of inactive genes is more heavily methylated than that of active ones; conversely demethylation of DNA reactivates gene expression in vivo and in vitro.

• Applied Biological Chemistry
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• 제46권4호
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• pp.280-284
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• 2003

농업용 살균제와 살충제로서의 활용성 진단과 예측평가 자료로 사용하기 위하여 상용화 된 살균제 133품목과 살충제 152품목의 활성 성분들에 대하여 소수성(LogP), 쌍극자능율(DM), HOMO 및 LUMO 에너지, molar refractivity(MR), polarizability(Pol), van der Waals 분자 표면적 및 부피(Vol), 분자량 및 수화 에너지(hydralion energy) 등, 10 가지의 다양한 물리-화학 파라미터들을 계산하였다. 그리고 살균제와 sterol 생합성 저해제 (DMI: demethylation inhibitor) 및 살충제와 acetylcholine esterase 저해제(AChE)이 가지는 특정한 물리-화학 파라미터들의 범위 값을 설정하였다. 그 결과에 기초하여 다양한 화합물들이 작물 보호제로서 살균제와 살충제로의 활용 가능성이 예측될 것으로 판단되었다.

• Journal of Plant Biotechnology
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• 제34권3호
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• pp.243-251
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• 2007

BRs의 생합성 경로는 $C_{28}-BRs$ 생합성 경로 외에 $C_{27}-BRs$ 생합성 경로가 존재함이 확인되었고, 최근 $C_{29}-BRs$의 생합성 경로가 존재함이 보고되어 BRs의 생합성 과정이 복잡하게 연결되어 있을 가능성이 예상되었다. 이에 $C_{29}-BRs$인 28-homoTE와 28-homoTY 등이 동정된 벼의 유식물을 대상으로 하여 $C_{29}-BR$인 25-homoCS의 대사 과정을 조사하였다. 그 결과 in vitro 효소변환 연구를 통해 28-homoCS은 CS와 26-nor-28-homoCS으로 전환됨을 확인 할 수 있었으며, 그 역반응인 CS에서 28-homoCS로 또는 26-nor-28-homoCS에서 28-homoCS로의 전환은 일어나지 않음을 알 수 있었다. 이는 $C_{29}-BRs$인 28-homoCS은 C-28위치의 demethylation에 의해 보다 강한 활성의 $C_{28}-BRs$인 CS로 생합성 되는 과정과 C-26 위치의 demethylation에 의해 26-nor-28-homoCS으로 생분해 되는 과정이 존재함을 최초로 확인하였다. 한편, $C_{28}-BRs$인 CS에서 BL로의 전환과 동일한 반응이 $C_{29}-BRs$에서도 일어나는지 확인하고자 하였으나 벼 유식물에서는 28-homoCS에서 28-homoBL로 전환되지 않음을 확인 할 수 있었다. 이는 $C_{29}-BRs$와 $C_{28}-BRs$의 생합성과정의 연결이 28-homoCS에서 CS를 통하고 있음을 알 수 있었다. 따라서 28-homoCS에서 CS로 전환되는 과정을 통하여 $C_{29}-BRs$ 또한 $C_{28}-BRs$ 와 동일한 과정을 거쳐 활성형의 CS로 전환됨을 확인 할 수 있었으며, BRs의 생합성은 $C_{27}-BRs$과 $C_{28}-BRs$의 생합성과정이 연결된 것처럼 $C_{29}-BRs$ 또한 $C_{28}-BRs$ 생합성 과정과 연결되어 있음을 확인 할 수 있었다. 즉, 활성형 BR인 CS은 $C_{27}-BRs$, $C_{28}-BRs$의 생합성 과정뿐만 아니라 $C_{29}-BRs$의 생합성 과정을 통하여 생성되는 과정이 식물체내에 존재함을 확인 할 수 있었다.

• 공업화학
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• 제10권5호
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• pp.666-671
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• 1999

본 연구에서 술폰화된 poly(phenylene sulfide)(SPPS)는 10%의 발연황산으로 PPST를 술폰화한 후 NaOH 수용액으로 demethylation하여 제조하였다. 유기용매에 용해되는 PPST는 methyl-(phenylthio)phenyl sulfoxide(MPPSO)의 자가축합 반응으로 합성되었다. SPPS는 $1200cm^{-1}$에서 $-SO_{3}H$의 비대칭 O=S=O 신축진동에 의한 흡수피크와 $621cm^{-1}$에서 S-O 신축진동에 의한 흡수피크가 관찰된 것으로 보아 술폰산기가 도입된 것을 알 수 있다. PPST의 술폰화를 $150^{\circ}C$에서 12시간 반응했을 때 반복단위당 1.48개의 술폰산기가 도입되었으며, 고온 GPC로 측정된 PPST와 SPPS의 중량평균분자량(Mw)은 각각 118323과 131204이었다. SPPS의 암모니아 가스 흡착능은 $9.67mmol\;NH_{3}/g$이었고, 활성탄, 실리카겔보다 월등히 높았다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권4호
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• pp.337-343
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• 2006

Trimethylamine dehydrogenase (TMADH, EC 1.5.99.7), an iron-sulfur flavoprotein that catalyzes the oxidative demethylation of trimethylamine to form dimethylamine and formaldehyde, was purified from Methylophaga sp. strain SK1. The active TMADH was purified 12.3-fold through three purification steps. The optimal pH and temperature for enzyme activity was determined to be 8.5 and $55^{\circ}C$, respectively. The $V_{max}\;and\;K_m$ values were 7.9 nmol/min/mg protein and 1.5 mM. A genomic DNA of 2,983 bp from Methylophaga sp. strain SK1 was cloned, and DNA sequencing revealed the open reading frame (ORF) of the gene coding for TMADH. The ORF contained 728 amino acids with extensive identity (82%) to that of Methylophilus methylotrophus $W_3A_1$.

• Molecules and Cells
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• 제20권3호
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• pp.423-428
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• 2005

Immediately after fertilization, a chromatin remodeling process in the oocyte cytoplasm extracts protamine molecules from the sperm-derived DNA and loads histones onto it. We examined how the histone H3-lysine 9 methylation system is established on the remodeled sperm chromatin in mice. We found that the paternal pronucleus was not stained for dimethylated H3-K9 (H3-$m_2K9$) during pronucleus development, while the maternal genome stained intensively. Such H3-$m_2K9$ asymmetry between the parental pronuclei was independent of $HP1{\beta}$ localization and, much like DNA methylation, was preserved to the two-cell stage when the nucleus appeared to be compartmentalized for H3-$m_2K9$. A conspicuous increase in H3-$m_2K9$ level was observed at the four-cell stage, and then the level was maintained without a visible change up to the blastocyst stage. The behavior of H3-$m_2K9$ was very similar, but not identical, to that of 5-methylcytosine during preimplantation development, suggesting that there is some connection between methylation of histone and of DNA in early mouse development.