• Journal of Radiation Protection and Research
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• v.11 no.2
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• pp.139-145
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• 1986

An improved mothod of assessing fuel status by analyzsis of the fission product in the reactor coolant system is proposed. The release mechanism of specific fission products is established for determination of the coefficients in the equations which relate the radioactivities with the amount of defected fuel. Knock-out and migration models are employed in the formulation of the release mechanism. The influence of the tramp uranium is quantified. Sample calculations were made for KNU 1 reactor system using the I-131 and I-133 concentrations in the primary coolant. The estimated number of defected fuel pins in the third and sixth cycles appeared to be $9.34{\pm}1.13\;and\;0.294{\pm}0.092$, respectively.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.335-341
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• 2017

The complexity of the bacterial recombination system is a barrier for the construction of bacterial mutants for the further functional investigation of specific genes. Several protocols have been developed to inactivate genes from the genus Pseudomonas. Those protocols are complicated and time-consuming and mostly do not enable easy construction of multiple knock-ins/outs. The current study describes a single and double crossover-recombination system using an optimized vector-free allele-exchange protocol for gene disruption and gene replacement in a single species of the family Pseudomonadaceae. The protocol is based on self-ligation (circularization) for the DNA cassette which has been obtained by overlapping polymerase chain reaction (Fusion-PCR), and carries an antibiotic resistance cassette flanked by homologous internal regions of the target locus. To establish the reproducibility of the approach, three different chromosomal genes (ncRNA31, rpoN, rpoS) were knocked-out from the root-associative bacterium Pseudomonas stutzeri A1501. The results showed that the P. stutzeri A1501 mutants, which are free of any plasmid backbone, could be obtained via a single or double crossover recombination. In order to optimize this protocol, three key factors that were found to have great effect on the efficiency of the homologous recombination were further investigated. Moreover, the modified protocol does not require further cloning steps, and it enables the construction of multiple gene knock-in/out mutants sequentially. This work provides a simple and rapid mutagenesis strategy for genome editing in P. stutzeri, which may also be applicable for other gram-negative bacteria.

• Journal of Embryo Transfer
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• v.28 no.3
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• pp.281-287
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• 2013

A major barrier to progress in pig to primate organ transplantation or cell therapy is the presence of terminal ${\alpha}$-1,3-galactosyl epitopes on the surface of pig cells. Therefore, the purpose of this experiment was to establish and cha- racterize mesenchymal stromal/stem cells (MSCs) derived from ${\alpha}$-1,3-galactosyltransferase (GalT) knock out (GalT KO) pig to confirm their potential for cell therapy. Bone marrow (BM)-MSCs from GalT KO pig of 1 month old were isolated by Ficoll-Paque PLUS gradient and cultured with A-DMEM + 10% FBS on plastic dishes in 5% $CO_2$ incubator at 38.5. GalT KO BM-MSCs were analyzed for the expression of CD markers ($CD45^-$, $29^+$, $90^+$ and $105^+$) and in vitro differentiation ability (adiopogenesis and osteogenesis). Further, cell proliferation capacity and cell aging of GalT KO BM-MSCs were compared to Wild BM-MSCs by BrdU incorporation assay (Roche, Germany) using ELISA at intervals of two days for 7 days. Finally, the cell size was also evaluated in GalT KO and Wild BM-MSCs. Statistical analysis was performed by T-test (P<0.05). GalT KO BM-MSCs showed fibroblast-like cell morphology on plastic culture dish at passage 1 and exhibited $CD45^-$, $29^+$, $90^+$ and $105^+$ expression profile. Follow in ginduction in StemPro adipogenesis and osteogenesis media for 3 weeks, GalT KO BM-MSCs were differentiated into adipocytes, as demonstrated by Oilred Ostaining of lipid vacuoles and osteocytes, as confirmed by Alizarinred Sstaining of mineral dispositions, respectively. BrdU incorporation assay showed a significant decrease in cell proliferation capacity of GalT KO BM-MSCs compared to Wild BM-MSCs from 3 day, when they were seeded at $1{\times}10^3$ cells/well in 96-well plate. Passage 3 GalT KO and Wild BM-MSCs at 80% confluence in culture dish were allowed to form single cells to calculate cell size. The results showed that GalT KO BM-MSCs($15.0{\pm}0.4{\mu}m$) had a little larger cell size than Wild BM-MSCs ($13.5{\pm}0.3{\mu}m$). From the above findings, it is summarized that GalT KO BM-MSCs possessed similar biological properties with Wild BM-MSCs, but exhibited a weak cell proliferation ability and resistance to cell aging. Therefore, GalT KO BM-MSCs might form a good source for cell therapy after due consideration to low proliferation potency in vitro.

• Tuberculosis and Respiratory Diseases
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• v.53 no.3
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• pp.275-284
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• 2002

Background : Gemcitabine is a new anti-cancer agent for treating non-small cell lung cancer. Functioning as an antimetabolite, it induces anti-cancer effects by suppressing DNA synthesis after being incorporated into the DNA as a cytosine arabinoside analogue. When Gemcitabine is incorporated into the DNA, the p53 gene may be activated by induction of the DNA defect. However, there are a few studies on the molecular mechanisms of Gemcitabine-induced cell death. This study examined the role of p53 in Gemcitabine-induced cell death. Methods : A549 and NCl-H358 lung cancer cells were used in this study. The cell viability test was done using a MTT assay at Gemcitabine concentrations of 10nM, 100nM, 1uM, 10uM and 100uM. A FACScan analysis with propium iodide staining was used for the cell cycle analysis. Western blot analysis was done to investigate the extent of p53 activation. For the functional knock-out of p53, stable A549-E6 cells and H358-E6 cells were transfected pLXSN-16E6SD which is over expresses the human papilloma virus E6 protein that constantly degrades p53 protein. The functional knock out of p53 was confirmed by Western blot analysis after treatment with a DNA damaging agent, doxorubicine. Results : Gemcitabine exhibited cell toxicity in dose-dependent fashion. The cell cycle analysis resulted in an S phase arrest. Western blot analysis significant p53 activation in time-dependent manner. Gemcitabine-induced cytotoxicity was reduced by 20-30% in the A549-E6 cells and the 30-40% in H358-E6 cells when compared with the A549-neo and H358-neo control cells. Conclusion : Gemcitabine induces an S phase arrest, as expected for the anti-metabolite, and activates the p53 gene, Furthermore, p53 might play an important role in Gemcitabine-induced cell death. Further investigation into the molecular mechanisms on how Gemcitabine activates the p53 gene and its signaling pathway are recommended.

• Molecules and Cells
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• v.38 no.1
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• pp.65-74
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• 2015

Carbohydrate antigens expressed on pig cells are considered to be major barriers in pig-to-human xenotransplantation. Even after ${\alpha}1,3$-galactosyltransferase gene knock-out (GalT-KO) pigs are generated, potential non-Gal antigens are still existed. However, to the best of our knowledge there is no extensive study analyzing N-glycans expressed on the GalT-KO pig tissues or cells. Here, we identified and quantified totally 47 N-glycans from wild-type (WT) and GalT-KO pig fibroblasts using mass spectrometry. First, our results confirmed the absence of galactose-alpha-1,3-galactose (${\alpha}$-Gal) residue in the GalT-KO pig cells. Interestingly, we showed that the level of overall fucosylated N-glycans from GalT-KO pig fibroblasts is much higher than from WT pig fibroblasts. Moreover, the relative quantity of the N-glycolylneuraminic acid (NeuGc) antigen is slightly higher in the GalT-KO pigs. Thus, this study will contribute to a better understanding of cellular glycan alterations on GalT-KO pigs for successful xenotransplantation.

• Journal of Plant Biotechnology
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• v.35 no.4
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• pp.307-316
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• 2008

Transposon-mediated insertional mutagenesis is one of powerful strategy for assessing functions of genes in higher plants. In this report, we have selected highly susceptible and tolerance plant by screening about high salt (3% NaCl) and cold stresses ($4^{\circ}C$) from F2 seeds of 30,000 Ac/Ds insertional mutagenesis lines in rice (Oryza sativa L. cv. Dongjin). In order to identify the gene tagging, insertion of Ds element was analyzed by Southern blot and these results revealed that 19 lines were matched genotype of selected lines with phenotype from the first selected 212 lines, and 13 lines have one copy of Ds elements. The Franking Sequence Tags (FSTs) of selected mutant lines showed high similarities with the following known function genes: signal transduction and regulation of gene expression (transpoter, protease family protein and apical meristem family protein), osmotic stress response (heat shock protein, O-methyltransferase, glyceraldehyde-3-phosphate dehydrogenase and drought stress induce protein), vesicle trafficking (SYP 5 family protein) and senescence associated protein. The expression pattern of 19 genes were analyzed using RT-PCR under the abiotic stresses of 9 class; 250mM NaCl, osmotic, drought, 3% $H_2O_2$, $100{\mu}M$ ABA, $100{\mu}M$ IAA, 0.1 ppm 2,4-D, $4^{\circ}C$ cold and $38^{\circ}C$ high temperature. Isolated knock-out genes showed the positive response about 250 mM NaCl, drought, $H_2O_2$, PEG, IAA, 2,4-D, ABA treatment and low ($4^{\circ}C$) and high temperature ($38^{\circ}C$). The results from this study indicate that function of selected knock-out genes could be useful in improving of tolerance to abiotic stresses as an important transcriptional activators in rice.

• Communications of Mathematical Education
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• v.36 no.3
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• pp.417-438
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• 2022

The purpose of this study is to suggest implications for mathematics teaching and learning when using AI-based educational platforms that support personalized mathematics learning. To this end, we selected five platforms(Knock-knock! Math Expedition, knowre, Khan Academy, MATHia, CENTURY) and analyzed how the AI-based educational platforms for mathematics reflect the three elements(PLP, PLN, PLE) to support personalized learning. The results of this study showed that although the characteristics of PLP, PLN, and PLE implemented on each platform varied, they were designed to form PLEs that allow learners to make their autonomous decisions about learning based on PLP and PLN. The significance of this study can be found in that it has improved the understanding and practicability of personalized mathematics learning with the AI-based educational platforms.

• BMB Reports
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• v.52 no.2
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• pp.111-112
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• 2019

Although many studies have reported that the breakdown of the blood-brain barrier (BBB) represents one of the major pathological changes in aging, the mechanism underlying this process remains relatively unexplored. In this study, we described that acid sphingomyelinase (ASM) derived from endothelial cells plays a critical role in BBB disruption in aging. ASM levels were elevated in the brain endothelium and plasma of aged humans and mice, resulting in BBB leakage through an increase in caveolae-mediated transcytosis. Moreover, ASM caused damage to the caveolae-cytoskeleton via protein phosphatase 1-mediated ezrin/radixin/moesin dephosphorylation in primary mouse brain endothelial cells. Mice overexpressing brain endothelial cell-specific ASM exhibited acceleration of BBB impairment and neuronal dysfunction. However, genetic inhibition and endothelial specific knock-down of ASM in mice improved BBB disruption and neurocognitive impairment during aging. Results of this study revealed a novel role of ASM in the regulation of BBB integrity and neuronal function in aging, thus highlighting the potential of ASM as a new therapeutic target for anti-aging.

• Journal of Microbiology
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• v.44 no.3
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• pp.311-319
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• 2006

Bud6p is a component of a polarisome that controls cell polarity in Saccharomyces cerevisiae. In this study, we investigated the role of the Candide albicans Bud6 protein (CaBud6p) in cell polarity and hyphal development. CaBud6p, which consists of 703 amino acids, had 37% amino-acid sequence identity with the Bud6 protein of S. cerevisiae. The homozygous knock-out of CaBUD6 resulted in several abnormal phenotypes, such as a round and enlarged cells, widened bud necks, and a random budding pattern. In hypha-inducing media, the mutant cells had markedly swollen tips and a reduced ability to switch from yeast to hypha. In addition, a yeast two-Hybrid analysis showed a physical interaction between CaBud6p and CaAct1p, which suggests that CaBud6p may be involved in actin cable organization, like Bud6p in S. cerevisiae. Taken together, these results indicate that CaBud6 plays an important role in the polarized growth of C. albicans.

• Hanyang Medical Reviews
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• v.34 no.3
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• pp.130-136
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• 2014

Animals find nutritious foods to survive, while avoiding aversive and toxic chemicals through the chemosensory faculties of olfaction and taste. The olfaction is comparatively well characterized, but the studies of taste are only recently developing since after 2000. Genetic, immunohistochemistry, and electrophysiological studies with knock-out transgenic mice opened up the taste field in mammals. Taste in insects has been only recently been studied after mammalian taste receptors were identified. Flies also discriminate the differences of sweet, salty and sour food, while being able to detect and reject potential foods contaminated with toxins or detrimental chemicals. These discriminatory abilities indicate that flies house basic taste receptors in their taste organs like humans. For the last decade, the sweet and bitter gustatory receptors in Drosophila have been characterized. In this review, we compare the taste anatomy between humans and insects. We also introduce five canonical taste sensations in Drosophila. In addition, we introduce new taste repertoires, that fruit flies can sense water and fatty acids as well as the carbonation buffer in beverage. These studies on simple model organisms will open up a new potential for scientists to further investigate these characteristics in vertebrates.