• Korean Journal of Materials Research
• /
• v.26 no.1
• /
• pp.1-7
• /
• 2016

The graphene oxides (GOs) were tested as a fluorescent quencher in the field of DNA-diagnostics. The various suspensions of GO nanoplates were prepared by changing the synthesis conditions. The suspensions were stable for at least 6 weeks by differing degrees of functionalization of various oxygen-containing groups of atoms. Depending on the properties of GO nanoplates, their fluorescent quenching abilities, which were determined by the amount of the tagged immobilized oligonucleotide, were also changed. GO suspension synthesized at $75^{\circ}C$ of reaction mixture showed the fluorescent quenching of 16.39 nmol/mg, which would be a potential substitution of molecular fluorescent quencher in test-systems for DNA-diagnostics.

• BMB Reports
• /
• v.37 no.2
• /
• pp.167-176
• /
• 2004

Although efficient antiviral lamivudine is used for HBV-infected patients, a prolonged treatment with nucleoside analogs often results in lamivudine-resistant variants. In this study, we evaluated the fidelity of the lamivudine-resistant variants. The FLAG-tagged wild-type (FPolE) and Met550 variants (FPolE/M550A, M550V, and M550I) of HBV DNA polymerases were expressed in insect cells then purified. Like many other reverse transcriptases, no $3'{\rightarrow}5'$ exonuclease activity was detected in the HBV DNA polymerase. Since there is no proofreading activity, then the use of the site-specific nucleotide misincorporation method is beneficial. From the $f_{ins}$ value analysis, it is evident that M550I and M550V exhibit higher fidelity values than the wild-type HBV DNA polymerase, while M550A exhibits similar fidelity values. It is therefore suggested that lamivudine resistance comes from the stringency to dNTP binding and the discrimination of dCTP and lamivudine in M550V and M550I.

• Clinical and Experimental Reproductive Medicine
• /
• v.36 no.1
• /
• pp.35-43
• /
• 2009

Objectives: Seminal concentration of tumor necrosis factor-alpha (TNF-${\alpha}$) relevant to sperm nuclear DNA integrity has not been studied. The present study aimed to evaluate seminal concentration of TNF-${\alpha}$ in correlation with sperm parameters and nuclear DNA integrity in asymptomatic healthy donors. Methods: Semen samples were obtained by masturbation from forty-five healthy donors. Results: Sperm quality was assessed by computer-assisted semen analysis and nuclear DNA integrity measured by the TUNEL assay in raw semen. TNF-${\alpha}$ concentrations were measured by ELISA in frozen-thawed seminal plasmas. Sperm DNA fragmentation rates were ranged between 1.9% and 53.0% (mean${\pm}$SD, 12.4${\pm}$9.6%). Univariate analysis revealed that DNA fragmentation rate was not associated with sperm concentration or motility but had a correlation with linearity negatively (r=-0.325, p=0.03) and age positively (r=0.484, p=0.001). The mean seminal concentration of TNF-${\alpha}$ was 4.9 pg/mL with a range from 1.1 to 22.6 pg/mL. The TNF-${\alpha}$ concentration had no correlation with clinically relevant parameters of sperm quality or nuclear DNA fragmentation rate. Conclusion: Our results indicate that sperm nuclear DNA fragmentation may be not associated with seminal TNF-${\alpha}$ level or sperm quality in asymptomatic healthy donors.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.6
• /
• pp.936-940
• /
• 2004

Doenjang (Korean soy paste) is one of the popular soybean based fermented foods in Korea. This study investigated the growth and DNA synthesis inhibitory effect of doenjang methanol extracts on AGS human gastric adenocarcinoma cells, Hep 3B human hepatocellular carcinoma cells and HT-29 human colon cancer cells. In order to determine an anticancer effect of doenjang methanol extracts, other soybean fermented foods and original materials were compared. The treatment of doenjang methanol extracts (200 $\mu\textrm{g}$/mL) to the AGS, Hep 3B and HT-29 cancer cells inhibited the growth of cancer cells by 80%, 77% and 86%, respectively. Compared to other soybean fermented foods and original materials, doenjang methanol extracts showed the highest growth inhibitory effect on different cancer cells. In addition, doenjang methanol extracts (200 $\mu\textrm{g}$/mL) significantly inhibited DNA synthesis of AGS and Hep 3B cancer cells by 76% and 59%, respectively. These results suggested that this anticancer effect of doenjang may be due to specific active compounds, which will be newly produced during soybean fermented process and not contained in soybean.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.11
• /
• pp.3099-3102
• /
• 2010

A label-free DNA detection method was developed for a simple electrochemical DNA sensor with a short assay time. Self-assembled monolayers of peptide nucleic acid were used as a probe on gold electrodes. The formation of the self-assembled monolayers on the gold electrodes was successfully checked by means of cyclic voltammetry. The target DNA, hybridized with peptide nucleic acid, can be detected by the anodic peak current of ferrocene dendrimers, which interact electrostatically with the target DNA. This anodic peak current was measured by square wave voltammetry at 0.3 V to decrease the detection limit on the order of the nanomolar concentrations. As a result, the label-free electrochemical DNA sensor can detect the target DNA in concentrations ranging from 1 nM to $1\;{\mu}M$ with a detection limit of 1 nM.

• Journal of Genetic Medicine
• /
• v.2 no.1
• /
• pp.31-34
• /
• 1998

The N-methylpurine-DNA glycosylase (MPG), a ubiquitous DNA repair enzyme, removes N-methylpurine and other damaged purines induced in DNA. Tissue-specific mRNA levels of the N-methylpurine-DNA glycosylase (MPG) were investigated in Balb/c mice of four different growing stages; newborn, 1, 4 and 8-weeks postpartum. MPG expressions in the newborn and the 8-week-old mice were the highest in thymus and testis, respectively. The tested tissues of the newborn mice had consistently higher MPG mRNA level than 8-week-old adults except in testis and thymus. The MPG mRNA level in testis was the lowest in the newborn mice, but it attained the highest in the 8-week-old mice. The levels of MPG mRNA among the different tissues in the newborn and the 8-week-old mice were more than 9.0 and 19.0-fold respectively. These results suggest that the of MPG expression was dependent on the growing stage and had tissue-specificity.

• BMB Reports
• /
• v.47 no.11
• /
• pp.609-618
• /
• 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.

• The Korean Journal of Zoology
• /
• v.37 no.2
• /
• pp.232-239
• /
• 1994

RecA protein plans a central role in homologous recombination and DNA repair in Escherichia cofi (E. colD. The function 8nd structure of this protein are universal in prokarvotes and also conserved in eukaryotes such as yeast. The RecA-like protein with 74 lInDa in size has already been identified and purified from a fission yeast Schizosaccharomyces pombe (5. pommel (Lee, 19911. From this study it was revealed that the RecA-like protein of 5. pombe was highly inducible to various DNA damaging agents and inhibitors of nucleotide pool svnthesizins enzymes. The cellular level of the 5. pombe RecA-like protein wi,u markedly increased, upto 5- to 10-fold, by treatment with various DNA-damains agents including ultraviolet (UV) light, methyl methanesulfonate WS),4-nitroquinoline-1-oxide (4-NQO), and mitomycin-C (MMC), similar to E. cofi RecA protein. Interestingly, the protein level was also increased by inhibitors of nucleotide pool forming enzlwnes such as methotrexate (MTX) and hvdroxvurea (HU). The most effective doses for the inducibility of 4-NQO, MMS, W, MMC, MTX, and HU were 0.2 Ug/ml, 30 mM, 200 J/ma, 0.4 $\mus/ml,$ 1 Ug/ml, and 100 mM, respectively. The range of effective duration time for the inducibilitv of RecA-like protein was from 270 to 450 mins. These results suggest that the 5. pombe RecA-like protein also platys an imortant role in cellular responses to DNA damage as in E. coli system.

• Journal of the Korean Applied Science and Technology
• /
• v.39 no.6
• /
• pp.916-923
• /
• 2022

Water samples were collected from three spots(Namcheon, Changwoncheon and Cheongwoonji) in Changwon and genomic DNA was isolated from them. Quantitative PCR was performed with the isolated DNA as template and primers targeting five different class A extended-spectrum beta-lactamase(ESBL) genes(bla_OXA-1, bla_SHV, bla_TEM, bla_CTX-M-1, bla_CTX-M-9). The number of total ESBL genes from each sample showed large variations between each sample. Thirty nanograms of DNA from Namcheon contained 1.93×10⁶ copies of ESBL genes whereas the same amount of DNA from Changwoncheon contained 1.47×10⁵ copies of ESBL genes. However, the same amount of DNA from Cheongwoonji pond contained only 9.5×10³ copies of ESBL genes. The ratio of each ESBL genes showed little difference between Namcheon river and Changwoncheon river, but DNA from Cheongwoonji pond showed a large difference from the rest. bla_OXA-1 gene was present at 65.3%, and bla_CTX-M-1 gene 33.6% for Namcheon comprising together almost 99%. bla_OXA-1 gene was present at 64.1%, and bla_CTX-M-1 gene 19.1% for Changwoncheon comprising together over 83%. bla_CTX-M-1 gene was present at 87.5% and bla_CTX-M-9 genes 9.8% for Cheongwoonji, a pond which is a closed and isolated environment.

• Environmental Mutagens and Carcinogens
• /
• v.10 no.2
• /
• pp.127-134
• /
• 1990

본 연구는 Chinese hamster ovary (CHO-KI) 배양세포에서 S-15분획에 의해 활성화된 bezo(a) pyrene (BP)과 3-methylcholanthrene(MC)에 의해 유발된 DNA단사절단과 DNA복제억제 및 그 회복과정에 미치는 한국산 인삼추출물 saponin의 영향을 조사하여 다음과 같은 결과를 얻었다. S-15분획으로 활성화된 10-5 M의 BP 또는 MC를 1.0-10ng/ml의 saponin과 함께 처리할 경우 BP와 MC단독처리군에 비해 DNA 단사절단률이 감소하였다. DNA 합성률은 활성화된 10-5M의 BP와 10-6 M의 MC에 의해 각각 50% 및 75% 억제되었으나, 0.1-10ng/ml의 saponin을 동시에 처리할 경우 DNA 합성억제률이 약 10% 이상 둔화되었다.