• Journal of Korean Society of Forest Science
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• v.101 no.2
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• pp.291-296
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• 2012

Triploids are a useful tool for biomass production and molecular breeding of trees with a long life span. Triploids of the poplar 'Hyunsasi' (Populus alba ${\times}$ P. glandulosa) have been developed by crossing between female diploids and a male tetraploid. The tetraploid was developed around the 1970s at Korea Forest Research Institute by colchicine-induced chromosome doubling. Seedlings of the $F_1$ generation were analyzed using flow cytometry to verify their ploidy status. The mean relative fluorescence index of 3 F1 poplars, labeled as Line- 1, Line-17, Line-18, were approximately 1.5 times higher than those of diploid poplars, and the results clearly indicated that they were triploids. The phenotype of the F1 poplars included larger leaves and thicker stem than diploids, and abnormal leaf morphology, especially in the triploid 'Line-18'. Three triploid lines developed roots more slowly and had less roots than diploid. However, 3 poplar cytotypes (2x, Line-1, Line-17) rooted within 10 days on MS medium. In contrast, compared with the 3 cytotypes, the Line-18 showed about 80% and 70% in the rooting rate and the number of roots. The triploid poplars could be directly utilized for biomass production and with their sterility, they could serve as basic material for genetic transformation. In addition, flow cytometric analysis proved to be an effective and reliable method for screening forest trees for their ploidy level.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.55-59
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• 2007

The study was carried out to develop transformants resisting to Phyophthora blight disease in the domestic pepper cultivar Subicho. In transforming of syn600 promoter with elicitin gene using Agrobacterium (LBA4404/pBI101 syn600-syn${\alpha}$-elicitin) to cotyledons of pepper, rate of shoot formation in 'Subicho' was 11.1% in medium containing 3 mg/L zeatin and 0.05 mg/L NAA, and also 12.8% in medium containing combination of 4 mg/L zeatin and 0.05 mg/L MAA. For PCR reaction using elicitin gene primer of transformants regenerated from cotyledons, we detected a specific band of 536 bp, and also showed strong signal at position of 536 bp in accordance with NPTII gene used as probe in Southern blot. Transformants pepper shown resistance to blight fungus was inoculated to seedlings of the $T_{1}\;and\;T_{2}$ transformants by concentration (density: zoo spore $10^{3}/mL$).

• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.186-195
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• 2015

Anthranilate synthase (AS) is a key enzyme in the biosynthesis of tryptophan (Trp), which is the precursor of bioactive metabolites like indole-3-acetic acid and other indole alkaloids. Alpha anthranilate synthase 2 (OsASA2) plays a critical role in the feedback inhibition of tryptophan biosynthesis. In this study, two vectors with single (F124V) and double (S126F/L530D) point mutations of the OsASA2 gene for feedback-insensitive ${\alpha}$ subunit of rice anthranilate synthase were constructed and transformed into wildtype Dongjinbyeo by Agrobacterium-mediated transformation. Transgenic single and double mutant lines were selected as a single copy using TaqMan PCR utilized nos gene probe. To select intergenic lines, the flanking sequence of RB or LB was digested with a BfaI enzyme. Four intergenic lines were selected using a flanking sequence tagged (FST) analysis. Expression in rice (Oryza sativa L.) of the transgenes resulted in the accumulation of tryptophan (Trp), indole-3-acetonitrile (IAN), and indole-3-acetic acid (IAA) in leaves and tryptophan content as a free amino acid in seeds also increased up to 30 times relative to the wildtype. Two homozygous event lines, S-TG1 and D-TG1, were selected for characterization of agronomic traits and metabolite profiling of seeds. Differentially expressed genes (DEGs), related to ion transfer and nutrient supply, were upregulated and DEGs related to co-enzymes that work as functional genes were down regulated. These results suggest that two homozygous event lines may prove effective for the breeding of crops with an increased level of free tryptophan content.

• Journal of Plant Biotechnology
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• v.35 no.1
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• pp.55-61
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• 2008

Previous studies on genetic transformation of chrysanthemum using cold regulated gene (BN115) have been conducted and the PCR and Real-Time PCR based method to determine the presence of the transferred cold regulated gene in the chrysanthemum was established. To check whether over-expression of BN115 gene in transgenic chrysanthemum will enhance their tolerance to cold stress, the transgenic chrysanthemum were grown under low temperature condition and several cold signalling including growth characteristics, stoma size and shape, SPAD value and ion leakage test were investigated. The transgenic chrysanthemum in the low temperature growth chamber grow much faster in term of the height, number and size of the leaves than those of wild-type plants and damage of transgenic plant caused by the low temperature was much less than that of wild-type plants. The stoma type and size of transgenic plant leaves grown at $5^{\circ}C$ were much similar to of wild-type plant cultured on $25^{\circ}C$ It has been found that SPAD value of transgenic plants was much higher than those of wild-type, but the EC density being lower under low temperature condition.

• Journal of Educational Research in Mathematics
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• v.11 no.2
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• pp.363-384
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• 2001

The purpose of this thesis is, through analysing the characteristics of the definitions in Korean school mathematics textbooks, to explore the levels of them and to make suggestions for definition - teaching as a mathematising activity, Definitions used in academic mathematics are rigorous. But they should be transformed into various types, which are presented in school mathematics textbooks, with didactical purposes. In this thesis we investigated such types of transformation. With the result of this investigation we tried to identify the levels of the definitions in school mathematics textbooks. And in school mathematics textbooks there are definitions which carry out special functions in mathematical contexts or situations. We can say that we understand those definitions, only if we also understand the functions of definitions in those contexts or situations. In this thesis we investigated the cases in school mathematics textbooks, when such functions of definition are accompanied. With the result of this investigation we tried to make suggestions for definition-teaching as an intellectual activity. To begin with we considered definition from two aspects, methods of definition and functions of definition. We tried to construct, with consideration about methods of definition, frame for analysing the types of the definitions in school mathematics and search for a method for definition-teaching through mathematization. Methods of definition are classified as connotative method, denotative method, and synonymous method. Especially we identified that connotative method contains logical definition, genetic definition, relational definition, operational definition, and axiomatic definition. Functions of definition are classified as, description-function, stipulation-function, discrimination-function, analysis-function, demonstration-function, improvement-function. With these analyses we made a frame for investigating the characteristics of the definitions in school mathematics textbooks. With this frame we identified concrete types of transformations of methods of definition. We tried to analyse this result with van Hieles' theory about levels of geometry learning and the mathematical language levels described by Freudenthal, and identify the levels of definitions in school mathematics. We showed the levels of definitions in the geometry area of the Korean school mathematics. And as a result of analysing functions of definition we found that functions of definition appear more often in geometry than in algebra or analysis and that improvement-function, demonstration-function appear regularly after demonstrative geometry while other functions appear before demonstrative geometry. Also, we found that generally speaking, the functions of definition are not explained adequately in school mathematics textbooks. So it is required that the textbook authors should be careful not to miss an opportunity for the functional understanding. And the mathematics teachers should be aware of the functions of definitions. As mentioned above, in this thesis we analysed definitions in school mathematics, identified various types of didactical transformations of definitions, and presented a basis for future researches on definition teaching in school mathematics.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.5965-5972
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• 2013

PIN1 is one member of the parvulin PPIase family. By controlling Pro-directed phosphorylation, PIN1 plays an important role in cell transformation and oncogenesis. There are many polymorphisms in the PIN1 gene, including rs2233678 and rs2233679 affecting the PIN1 promoter. Recently, a number of case-control studies were conducted to investigate the association between PIN1 gene rs2233678 and rs2233679 polymorphism and cancer risk. However, published data are still conflicting. In this paper, we summarized data for 5,427 cancer cases and 5,469 controls from 9 studies and attempted to assess the susceptibility of PIN1 gene polymorphism to cancers by a synthetic meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the relationship. All analyses were performed using Stata software. Our results suggested that rs2233678 represented a protective factor in overall analysis (CC vs GG: OR= 0.697, 95%CI: 0.498-0.976; CG vs GG: OR=0.701, 95%CI: 0.572-0.858; Dominant model: OR= 0.707, 95%CI: 0.590-0.847; C allele vs G allele: OR=0.734, 95%CI: 0.623-0.867) and especially for squamous cell carcinoma of the head and neck, lung cancer and breast cancer in Asians and Caucasians. The rs2233679 polymorphism was significantly associated with decreased cancer risk in overall analysis (CT vs CC: OR=0.893, 95%CI=0.812-0.981; Dominant model: OR=0.893, 95%CI=0.816-0.976; T allele vs C allele; OR=0.947, 95%CI=0.896-1.000) and especially in Asians. In conclusion, our meta-analysis suggested that -842G>C (rs2233678) and -667C>T (rs2233679) may contribute to genetic susceptibility for cancer risks. Further prospective research with larger numbers of worldwide participants is warranted to draw comprehensive and firm conclusions.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3335-3340
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• 2016

Background: Oral submucous fibrosis (OSF) is a precancerous condition with a 4 to13% malignant transformation rate. Related to the habit of areca nut chewing it is mainly prevalent in South-east Asian countries where the habit of betel quid chewing is frequently practised. On chewing, alkaloids and polyphenols are released which undergo nitrosation and give rise to N-nitrosamines which are cytotoxic agents. CYP450 is a microsomal enzyme group which metabolizes various endogenous and exogenous chemicals including those released by areca nut chewing. CYP1A1 plays a central role in metabolic activation of these xenobiotics, whereas CYP2E1 metabolizes nitrosamines and tannins. Polymorphisms in genes that code for these enzymes may alter their expression or function and may therefore affect an individuals susceptibility regarding OSF and oral cancer. The present study was therefore undertaken to investigate the association of polymorphisms in CYP1A1 m2 and CYP2E1 (RsaI/PstI) sites with risk of OSF among areca nut chewers in the Northern India population. A total of 95 histopathologically confirmed cases of OSF with history of areca nut chewing not less than 1 year and 80, age and sex matched controls without any clinical signs and symptoms of OSF with areca nut chewing habit not less than 1 year were enrolled. DNA was extracted from peripheral blood samples and polymorphisms were analyzed by PCR-RFLP method. Gene polymorphism of CYP1A1 at NcoI site was observed to be significantly higher (p = 0.016) in cases of OSF when compared to controls. Association of CYP1A1 gene polymorphism at NcoI site and the risk of OSF (Odd's Ratio = 2.275) was also observed to be significant. However, no such association was observed for the CYP2E1 gene polymorphism (Odd's Ratio = 0.815). Our results suggest that the CYP1A1 gene polymorphism at the NcoI site confers an increased risk for OSF.

• Journal of Plant Biotechnology
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• v.34 no.4
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• pp.285-291
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• 2007

This study describes conditions for the mass production of activation-tagged mutant hairy root lines of ginseng by cocultivation with Agrobacterium rhizogenes. Because it is not currently possible to produce progeny from transgenic ginseng, a loss-of-function approach for functional genomics cannot be appliable to this species. A gain-of-function approach is alternatively the choice and hairy root production by cocultivation of A. rhizogenes would be most practical to obtain a large number of mutants. Various sources of explants were subjected to genetic transformation with various strains of A. rhizogenes harboring the activation-tagging vector pKH01 to determine optimum conditions for the highest frequency of hairy root formation on explants. Petiole explants cocultivated with A. rhizogenes R1000 produced hairy roots at a frequency of 85.9% after 4 weeks of culture. Conditions for maximum growth or branching rate of hairy roots were also investigated by using various culture media. Petiole explants cultured on half strength Schenk and Hildebrandt medium produced vigorously growing branched roots at a rate of 2.6 after 4 weeks of culture. A total of 1,989 lines of hairy root mutants were established in this study. These hairy root lines will be useful to determine functions of genes for biosynthesis of ginsenosides.

• Journal of Plant Biotechnology
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• v.37 no.2
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• pp.125-132
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• 2010

Rice is the staple food of more than 50% of the worlds population. Cultivated rice has the AA genome (diploid, 2n=24) and small genome size of only 430 megabase (haploid genome). As the sequencing of rice genome was completed by the International Rice Genome Sequencing Project (IRGSP), many researchers in the world have been working to explore the gene function on rice genome. Insertional mutagenesis has been a powerful strategy for assessing gene function. In maize, well characterized transposable elements have traditionally been used to clone genes for which only phenotypic information is available. In rice endogenous mobile elements such as MITE and Tos (Hirochika. 1997) have been used to generate gene-tagged populations. To date T-DNA and maize transposable element systems has been utilized as main insertional mutagens in rice. A main drawback of a T-DNA scheme is that Agrobacteria-mediated transformation in rice requires extensive facilities, time, and labor. In contrast, the Ac/Ds system offers the advantage of generating new mutants by secondary transposition from a single tagged gene. Revertants can be utilized to correlate phenotype with genotype. To enhance the efficiency of gene detection, advanced gene-tagging systems (i.e. activation, gene or enhancer trap) have been employed for functional genomic studies in rice. Internationally, there have been many projects to develop large scales of insertionally mutagenized populations and databases of insertion sites has been established. Ultimate goals of these projects are to supply genetic materials and informations essential for functional analysis of rice genes and for breeding using agronomically important genes. In this report, we summarize the current status of Ac/Ds-mediated gene tagging systems that has been launched by collaborative works from 2001 in Korea.

• Journal of Plant Biotechnology
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• v.40 no.3
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• pp.156-162
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• 2013

Plant tolerance to drought is a beneficial trait for stabilizing crop productivity under water deficits. Here we report that genetically engineered Chinese cabbage expressing Arabidopsis $H^+$-pyrophosphatase (AVP1) shows enhanced physiological parameters related to drought tolerance. In comparison with wild type plants under soil water deficit stress created by cessation of irrigation, soil water potential in pot with AVP1-expressing plants was more rapidly decreased that might lead to increased relative water content in leaves, while both genotypes had indistinguishable wilting phenotypes. Transgenic plants subjected to drought treatment also exhibited higher photosystem II quantum yield in addition to lower electrolyte leakage and $H_2O_2-3,3^{\prime}$-diaminobenzidine content when compared to wild type plants.