• BMB Reports
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• v.42 no.6
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• pp.315-323
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• 2009

In order to elucidate ultimate biological function of the genome, the model animal system carrying mutations is indispensable. Recently, large-scale mutagenesis projects have been launched in various species. Especially, the mouse is considered to be an ideal model to human because it is a mammalian species accompanied with well-established genetic as well as embryonic technologies. In 1990', large-scale mouse mutagenesis projects firstly initiated with a potent chemical mutagen, N-ethyl-N-nitrosourea (ENU) by the phenotype-driven approach or forward genetics. The knockout mouse mutagenesis projects with trapping/conditional mutagenesis have then followed as Phase II since 2006 by the gene-driven approach or reverse genetics. Recently, the next-generation gene targeting system has also become available to the research community, which allows us to establish and analyze mutant mice carrying an allelic series of base substitutions in target genes as another reverse genetics. Overall trends in the large-scale mouse mutagenesis will be reviewed in this article particularly focusing on the new advancement of the next-generation gene targeting system. The drastic expansion of the mutant mouse resources altogether will enhance the systematic understanding of the life. The construction of the mutant mouse resources developed by the forward and reverse genetic mutagenesis is just the beginning of the annotation of mammalian genome. They provide basic infrastructure to understand the molecular mechanism of the gene and genome and will contribute to not only basic researches but also applied sciences such as human disease modelling, genomic medicine and personalized medicine.

• Korean Journal of Pharmacognosy
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• v.35 no.1 s.136
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• pp.28-34
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• 2004

DNA damage induced by reactive oxygen species (ROS) seems to play an important role in the induction of mutation and cancer. Hydrogen peroxide $(H_2O_2)$ has been shown to induce a variety of genetic alterations, probably by the generation of hydroxyl radicals via Fenton reaction. In this study, we examined the ability of medicinal herbs in the suppression of $H_2O_2$-induced mutagenesis. Human fibroblast GM00637 cells were treated with $H_2O_2$ in the presence or absence of medicinal herbs, and $H_2O_2$-induced mutant frequency was measured at the hypoxanthine guanine phosphoribosyl transferase (HPRT) locus. Treatment of cells with various doses of $H_2O_2$ caused a significant increase of the HPRT mutant frequency. However, pretreatment of cells with several medicinal herbs reduced $H_2O_2$-induced mutant frequency. The strong antimutagenic effects were observed from the methylene chloride and ethyl acetate fractions of Selaginella tamariscina, Panax ginseng, and Angelica acutiloba; ethyl acetate fractions of Rehmania glutinosa, Leonurus sibiricus, Curcuma zedoaria and Commiphora molmol; butanol fractions of Scutellaria barbata, Tribulus terrestris, Curcuma zedoaria, Cyperus rotundus and Carthamus tinctorius, which were more than 60% inhibition of $H_2O_2$-induced mutant frequency at the HPRT locus.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.57-65
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• 1998

This study was conducted to develop a resistant tobarro against Potato virus Y (PVY) by transformation of the plants with genetically engineered viral genes. The complimentary DNAs (cDNAS) of potato virus Y-necrosis strain (PVY-Vn) replicase mutant genes (3'-deleted, 5'-deleted and ADD-mutant Nlbs) were synthesized through RT-PCR by using purified PVY-VN RNA and synthesized primers, and cloned in the sense orientation into a plant expression vector (pMBPI), The cDNAS of the genes were transferred into Agrobacterium tumefaciens LBA 4404, and then transformed into tobacco (Nicotiana tabacum cv. Burley 21) plants. Regenerated plants were tested for PVY resistance by inoculation test; 13 transgenic plants including 7 for 3'-deleted Nlb, 3 for 5'-deleted Nlb, and 3 for ADD-mutant Nlb appeared to be resistant at 4 weeks after inoculation with PVY-VN. Among the 13 transgenic tobacco plants, 8 plants had no symptom up to 14 weeks after inoculation. The progenies ($T_1$) from self-fertilization of the transgenic lines varied 0.0% to 81.2% in their resistance (% of resistant plants). The analysis of Nlb-31deleted, -5'deleted and -ADD mutant in the $T_1$ plants by polymerase chain reaction (PCR) showed that Nlb-3'deleted, -5'deleted and -ADD mutants were detected in all of the resistant plants. These results suggest that the PVY resistance was inherited in the $T_1$ generation.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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• pp.9-9
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• 2021

Mutation breeding is useful for improving agronomic characteristics of various crops. In this study, we constructed soybean Mutant Diversity Pool (MDP) from 1,695 gamma-irradiated mutants through two selection phases over M1 to M12 generations; we selected 523 mutant lines exhibiting at least 30% superior agricultural characteristics, and, second, we eliminated redundant morphological phenotypes in the M12 generation. Finally, we constructed 208 MDP lines and investigated 11 agronomic traits. We then assessed the genetic diversity and inter-relationships of these MDP lines using target region amplification polymorphism (TRAP) markers. Among the different TRAP primer combinations, polymorphism levels and PIC values averaged 59.71% and 0.15, respectively. Dendrogram and population structure analyses divided the MDP lines into four major groups. According to an analysis of AMOVA, the percentage of inter-population variation among mutants was 11.320 (20.6%), whereas mutant inter-population variation ranged from 0.231 (0.4%) to 14.324 (26.1%). Overall, the genetic similarity of each cultivar and its mutants were higher than within other mutant populations. In an analysis of the genome-wide association study (GWAS) using based on the genotyping-by-sequencing (GBS), we detected 66 SNPs located on 13 different chromosomes were found to be highly associated with four agronomic traits: days of flowering (33 SNPs), flower color (16 SNPs), node number (6 SNPs), and seed coat color (11 SNPs). These results are consistent with those previously reported for other genetic resource populations, including natural accessions and recombinant inbred line. Our observations suggest that genomic changes in mutant individuals induced by gamma rays occurred at the same loci as those of natural soybean population. This study has demonstrated that the integration of GBS and GWAS can serve as a powerful complementary approach to gamma-ray mutation for the dissection of complex traits in soybean.

• The Plant Pathology Journal
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• v.39 no.6
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• pp.592-599
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• 2023

A defective RNA3 (D3Yα) of strain Y of cucumber mosaic virus (CMV-Y) was examined on host-specific maintenance, experimental conditions, and a viral factor required for its generation in plants. D3Yα was stably maintained in cucumber but not in tomato plants for 28 days post inoculation (dpi). D3Yα was generated in Nicotiana tabacum or N. benthamiana after prolonged infection in the second and the third passages, but not in plants of N. benthamiana grown at low temperature at 28 dpi or infected with CMV-Y mutant that had the 2b gene deleted. Collectively, we suggest that generation and retention of D3Yα depends on potential host plants and experimental conditions, and that the 2b protein has a role for facilitation of generation of D3Yα.

• Journal of Plant Biotechnology
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• v.43 no.4
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• pp.411-416
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• 2016

Next-generation sequencing allows the identification of mutations responsible for mutant phenotypes by whole-genome resequencing and alignment to a reference genome. However, when the resequenced cultivar/line displays significant structural variation from the reference genome, mutations in the genome regions absent in the reference cannot be identified by simple alignment. In this review, we report the current status and prospects in identification of genes in mutant phenotypes, by using the methods MutMap, MutMap-Gap, and MutMap+. These methods delineate a candidate region harboring a mutation of interest, followed by de novo assembly, alignment, and identification of the mutation within genome gaps. These methods are likely to prove useful for cloning genes that exhibit significant structural variations, such as disease resistance genes of the nucleotide-binding site-leucine rich repeat (NBS-LRR) class.

• The Korean Journal of Mycology
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• v.21 no.4
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• pp.285-292
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• 1993

For the enzymatic conversion of 5'-XMP to 5'-GMP, partially purified XMP aminase from Escherichia coli was coupled with the yeast, Saccharomycrs cerevisiae, capable of ATP regeneration through glycolytic pathway. In order to elevate the level of XMP aminase in E. coli, $guaB^{-}(IMP\;dehydrogenase-less)$ mutant were introduced, and the yeast used as ATP supplier was treated by some method to increase its membrane permeability. The optimum conditions for efficient conversion reaction by energy-coupled system were investigated. As the results, a CH 41, $guaB^-$ mutant of E. coli K-12, showed 2.75 fold increase in the level of XMP aminase, compared with its parent cell. And the lyophylized yeast was the most effective at the ATP supplier. The optimum temperature and pH of conversion reaction were $40{\circ]C$ and pH 7.4, and the highest conversion ratio was shown under the reaction condition of 100 mM glucose, 100 mM inorganic phosphate and 6 mM AMP. When 36 units/ml XMP aminase used under the above conditions, the amount of 60 mg/ml yeast was sufficient to be used. Under the optimum condition, 71% of 1.8 mM(65.6 mg/100 ml) 5'-XMP was converted to 5'-GMP within 8 hr.

• Journal of Crop Science and Biotechnology
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• v.11 no.3
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• pp.181-186
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• 2008

To assess the potential as biofortified rice varieties, new endosperm and grain mutant lines were selected from $M_4$ generation seeds of the rice cultivar Shindongjin, which were either $\gamma$-irradiated or treated with N-methyl-N-nitrosourea(MNU) and lipid, sugar, and tocopherol content were analyzed. Amylose content in non-waxy mutants ranged from 8.8% in SM-4, a dull-type mutant, to 29.5% in SM-51, compared to 18.9% in the parental variety, Shindongjin. SM-23, a floury-type mutant, contained 0.09 ${\mu}g/g$ $\alpha$-tocopherol(40.9% of total tocopherol), was three times higher than in the parental variety. SM-32, a giant embryo-type mutant, had a 2.2-fold higher total tocopherol content, 2.1-fold higher $\alpha$-tocopherol, and 5.5-fold higher $\delta$-tocopherol content(47.3% of total tocopherol) than the parental variety(0.13 ${\mu}g/g$). Total free sugar content was elevated in all selected mutants and 1.2-8.6 times higher than in the parental variety(11.38 ${\mu}g/g$). These increased sugar levels were due to increase in sucrose concentration. SM-23(floury-type mutant) and SM-51(high amylose-type mutant) had 4.6 and 7.0 times more sugar, respectively, than the parental variety(11.38 ${\mu}g/g$). With relatively high concentrations, most mutants showed elevated fatty acid content in the SM 32(giant embryo-type) and SM-51(high amylose-type) mutants, at 124.56 and 89.59 mg/g, respectively. All selected mutants displayed valuable characteristics for the development of new varieties in rice-breeding programs.

• Development and Reproduction
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• v.23 no.4
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• pp.385-390
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• 2019

Upon gene inactivation in animal models, the zebrafish (Danio rerio) has become a useful model organism for many reasons, including the fact that it is amenable to various forms of genetic manipulation. Genome editing is a type of genetic engineering in which DNA is inserted, deleted, modified, or replaced in the genome of a living organism. Mainly, CRISPR (clustered regularly interspaced short palindromic repeats) Cas9 (CRISPR-associated protein 9) is a technology that enables geneticists to edit parts of the genome. In this study, we utilized this technology to generate an mmp15b mutant by using zebrafish as an animal model. MMP15 is the membrane-type MMP (MT-MMP) which is a recently identified matrix metalloproteinase (MMP) capable of degrading all kinds of extracellular matrix proteins as well as numerous bioactive molecules. Although the newly-established mmp15b zebrafish mutant didn't exhibit morphological phenotypes in the developing embryos, it might be further utilized to understand the role of MMP15 in liver-related diseases, such as liver fibrosis, and associated pathogeneses in humans.

• Proceedings of the PSK Conference
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• 2001.04a
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• pp.48-55
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• 2001

When an elongating RNA polymerase encounters DNA damage on the template strand of a transcribed gene it can either be arrested by or be transcribed through the lesion. Lesions that arrest RNA polymerases are thought to be subject to transcription-coupled repair, whereas that damage that is bypassed can cause miscoding, resulting in mutations in the transcript (transcriptional mutagenesis). We have developed a technique using a plasmid-based luciferase reporter assay to determine the extent to which a particular type of DNA base modification is capable of causing transcriptional mutagenesis in vivo. The system uses Escherichia coli strains with different DNA repair backgrounds and is designed to detect phenotypic changes caused by transcriptional mutageneis under nongrowth conditions. In addition, this method is capable of indicating the extent to which a particular DNA repair enzyme (or pathway) suppresses the occurrence of transcriptional mutagenesis. Thus, this technique provides a tool with which the effects of various genes on non-replication-dependent pathways resulting in the generation of mutant proteins can be gauged.