• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.59-66
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• 1996

Virginiae butanolide C(VB-C) is one of the butyrolactone autoregulators, which triggers the productin of virginiamycin in Streptomyces virginiae. To further understand the mechanism of virginiamycin induction, we isolated three mutants from S. virginiae by N-methyl-N'-nitrosoguanidine (NTG) treatment. The characteristics of the three mutants were confirmed as follows: the mutant No. 1 delayed the production of the VB-C, receptor and antibiotics; the mutant No.3 hyperproduced receptor; the mutant No.4 failed to produce the VB-C. The addition of synthetic VB-C couldn't induce the production of antibiotics in the mutant No.1 due to delayed production of receptor, could provoke the production of larger amount of antibiotics than parental wild type strain in the mutant No.3 due to the presence of large amount of receptor, and could induce production of very small amount of antibiotics in the mutant No.4 due to the absence of VB-C. Antimicrobial spectrum and HPLC analysis of the mutant No.1 and No.3 suggested that the VB-C might have a specific ability to induce the production of virginiamycin M and S. These results imply that the VB-C has an ability to trigger the production of virginiamycin under receptor existence in S. virginiae.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.1
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• pp.23-27
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• 1998

Inhibition of nodule formation and nitrogen fixation by soil nitrogen, primarily nitrate, is well known in legume plants. The present study was undertaken to evaluate the effect of ${NO_3}^-$ on the nodulation, nitrogenase activity, and growth of supernodulating soybean mutant and its wild type. A greenhouse study was conducted to compare two of supernodulating mutants, 'SS2-2' and 'nts 382', with the normal nodulating cultivar 'Sinpaldalkong 2' when grown in a 1-l styroform cup filled with sand, and fertilized with five levels of ${NO_3}^-$ (0, 2, 4, 8, and 12 mM). During the growth period, each plant was supplied two or three times a week with 50 mL of nutrient solution. Supernodulating soybean mutants, SS2-2 and nts 382, showed more nodules and nodule mass, and greater $C_2\;H_2$ activity than the wild type, Sinpaldalkong 2, regardless of the level of exogeneous nitrogen supply. On the other hand, total dry weight of SS2-2 mutant, which was smaller than Sinpaldalkong 2, did not respond to the various ${NO_3}^-$-N levels. This suggested that supernodulating SS2-2 mutant could maintain fairly high total dry weight at the low ${NO_3}^-$-N level, even in the absence of exogeneous ${NO_3}^-$-N in the nutrient solution. From the reduced top growth and high nitrogen fixing ability of supernodulating mutants, it was surmised that supernodulating mutant could potentially protect agricultural environments from pollution through the reduction in nitrogen fertilization as well as maintain fairly high yield with increasing planting density.

• Korean Journal of Plant Resources
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• v.19 no.6
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• pp.706-715
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• 2006

Nitrate reductase deficient (NR) mutant lines were selected indirectly by their resistance to 100mM chlorate in cell cultures of P. parviflora. A total of 585 chlorate resistant lines were confirmed by a second passage on a high concentration of chlorate. Frequency of spontaneous mutation was $9.7{\times}10^{-7}$ in 3 month old suspension-cultured cells, and in non-selective media containing amino acids as sole nitrogen source. The frequency of mutation could be increased up to 11-fold by culture for 12 months. Out of 40 randomly selected calli, 22 were fully deficient in NR. The rest of the clones contained a decreased level of NR activity. Further characterization was carried out in 13 mutant lines which were fully deficient in NR and in 5 mutant lines containing residual (0-7.0%) NR activity, as compared to wild-type cells cultured on the same medium. The $NR^-$ mutants were tentatively classified as defective in the NR apoenzyme (nia-type; 11 mutant lines including the 5 with residual NR activity) or in the molybdenum cofactor (cnx-type; 7 mutant lines) by the XDH activity. The cnx-type could be further classified into two groups. In one group (5 mutant lines) of these, the NR activity could be partially restored by nonphysiologically high (1.0mM) molybdate in the culture medium. Both types of $NR^-$ mutants were unable to grow on minimal medium containing nitrate as sole nitrogen source, but grew well on amino acids. They also proved to be extremely sensitive to the standard medium ($MSP_1$) containing nitrate and ammonium. Shoot regeneration was obtained only in the $NR^-$ mutants, which contained residual NR activity, but they so far have failed to grow into plants.

• Food Science and Biotechnology
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• v.15 no.3
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• pp.437-440
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• 2006

To explore the possible usefulness of ${\beta}$-glucans as natural antioxidants, the antioxidant profiles of ${\beta}$-glucan, extracted from Saccharomyces cerevisiae KCTC 7911, and water soluble and insoluble mutant ${\beta}$-glucan, isolated from yeast mutant S. cerevisiae IS2, were examined by five different in vitro evaluation methods: lipid peroxidation value (POV), nitric oxide (NO), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, reducing power, and ${\beta}$-carotene diffusion assay. The antioxidant activities of all ${\beta}$-glucans evaluated in POV test were comparable to or better than that of the known antioxidant, vitamin C. Remarkably, the ${\beta}$-glucan and water insoluble mutant ${\beta}$-glucan possessed 2.5-fold more potent activity than vitamin C at a dosage of 2 mg. Although vitamin C showed 100-fold greater activity than all ${\beta}$-glucans in NO and DPPH tests for measuring the radical scavenging capacity, all ${\beta}$-glucans revealed higher radical scavenging activity than the known radical scavenger, N-acetyl-L-cysteine (NAC), in DPPH test. The water insoluble mutant ${\beta}$-glucan had 2.6- and 5-fold greater antioxidative activity than water soluble ${\beta}$-glucan in NO and DPPH tests, respectively, showing that all ${\beta}$-glucans were able to scavenge radicals such as NO or DPPH. While all ${\beta}$-glucans revealed lower antioxidant profiles than vitamin C in both reducing power activity and ${\beta}$-carotene agar diffusion assay, the ${\beta}$-glucan and water insoluble mutant ${\beta}$-glucan did show a marginal reducing power activity as well as a considerable ${\beta}$-carotene agar diffusion activity. These results confirmed the potential usefulness of these ${\beta}$-glucans as natural antioxidants.

• Journal of Radiation Industry
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• v.4 no.4
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• pp.307-312
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• 2010

Plants have evolved physiological, biochemical and metabolic mechanisms to increase their survival under the adverse conditions. This present study has been performed to select salt-tolerant rice mutant lines through in vivo and in vitro mutagenesis with gamma-rays. For the selection of the salt-tolerant rice mutants, we conducted three times of selection procedure using 1,500 gamma ray mutant lines resulted from an embryo culture of the original rice cv. Dongan (wild-type, WT): first, selection in the a nutrient solution with 171 mM NaCl; second, selection under in vitro condition with 171 mM NaCl; and third, selection in a reclaimed saline land. Based on a growth comparison of the entries, out of the mutant lines, two putative 2 salt tolerant (ST) rice mutant lines, ST-87 and ST-301, were finally selected. The survival rate of the WT, ST-87 and ST-301 were 36.6%, 60% and 66.3% after 7 days in 171 mM NaCl treatment, respectively. The WT and two salt tolerant mutant lines were used to analyze their genetic variations. A total of 21 EcoRI and Msel primer combinations were used to analyze the genetic relationship of among the two salt-tolerant lines and the WT using the ABI3130 capillary electrophoresis system. In the AFLP analysis, a total of 1469 bands were produced by the 21 primer combinations, and 700 (47.6%) of them were identified as having polymorphism. The genetic similarity coefficients were ranged from 0.52 between the ST-87 and WT to 0.24 between the ST-301 and the WT. These rice mutant lines will be used as a control plot for physiological analysis and genetic research on salt tolerance.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.223-227
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• 2008

In rice, tillering is an important trait determining yield. To study tillering at the agricultural and molecular aspects, we have examined a spontaneous rice mutant that showed reduction in the number of culms. The mutant was derived from a $F^6$ line of the cross of Junambyeo*4 / IR72. It could produce, on average, 4 tillers per hill in the paddy field while wild-type plants usually have 15. Except the reduced culm numbers, they also show pale green phenotypes. The phenotypes of this mutant were co-segregated as the monogenic Mendelian ratio (${\chi}^b=0.002$, p=0.969). In order to locate a gene responsible for the rcn phenotype, the mutant with the japonica genetic background was crossed with Milyang21 of the indica background. Bulked segregant analysis was used for rapid determination of chromosomal location. Three SSR markers (RM551, RM8213, and RM16467) on chromosome 4 were genetically associated with the mutant phenotype. Each of the 217 $F_2$ plants was genotyped with simple sequence length polymorphisms. The data showed that RM16572 on chromosome 4 was the closest marker that showed perfect co-segregation among the $F_2$ population. We suggest the new rcn gene studied here name as $rcn10^t$ because there was no report which exhibit a rcn phenotype with a pleiotropic effect of pale green (chlorophyll deficiency), and mapped at same position on chromosome 4.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.31-31
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• 1999

Characterization of mutant mice has been utilized as an animal model for the study of human inherited diseases. In addition to the pathogenesis stduy using the mutant mice, the mice have been used for the identification of the genes causing the phenotypes. Functional cloning and positional cloning are two approaches, depending on the phenotypes of the mutant mice. Though it takes a long time positional cloning has been well used to identify the gene of which function can not be presumed from the mouse phenotype. Recently by the advance of the molecular tools and the human genome project close to 10,000 genetic markers are developed to make the procedure faster. We obtained a new mutant mouse, sims, spontaneously arose and the affected mouse has a mild tremor and seizure was observed. Homozygote in either sex is sterile since uterus growth in female and seminal vesicle in male are not induced for the growth in puberty, implying the abnormal hormonal regulation during puberty. Supporting this, there is no detectable testosterone in the serum of the mutant male and the brain of the mutant is 30% heavier than littermate. To identify the location of the mutated gene, intraspecies cross to CAST/Ei was carried out and the 37 affected mice was analyzed for the linkage. The gene was mapped on chromosome 18, 20 cM from the centromere. More than 500 F2 progenies have been analyzed for the linkage and the locus becomes narrow within 3cM between Egrl and Fgf gene.f gene.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.66.2-66
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• 2003

A gain-of-function mutant, SHM-11 obtained through gamma-ray mutagenesis, is resistant to rice blast caused by Magnaporthe grisea while wild type Sanghaehyanghyella is highly susceptible to the same disease. The resistance in the mutant was not race-specific when we tested with four races (KJ-201, KI-1113a, KI-313, KI-409) of M. grisea. To identify genes involved disease resistance in the gain-of-function mutant, genes specifically expressed in the mutant were selected by suppression subtractive hybridization using cDNAS of blast-inoculated mutant and wild type as a tester and a driver, respectively, Random 200 clones from the subtracted library were selected and analyzed by DNA sequencing. The sequenced genes represented three major groups related with disease resistance； genes encoding PR proteins, genes probably for phytoalexin biosynthesis, and genes involved in disease resistance signal transduction. A gene encoding a putative receptor-like protein kinase was identified as highly expressed only in the gain-of-function mutant after blast infection. The role of the putative receptor-like protein kinase gene during blast resistance will be further studied.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.86-86
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• 2022

Sorghum (Sorghum bicolor) is increasingly important as a biomass crop worldwide. Its genetic diversity provides a large range of biochemical composition suitable for various uses as bioplastics. Phenolic compounds are the main compounds of lignocellulosic residues, which can be used as a source of active components for their use in active packaging materials. In this research, we investigated the total phenolic content (TPC) and the total flavonoid content (TFC) among 60 mutant lines (early heading, high biomass and dwarfness) and their original cultivars. Sixty sorghum mutant lines were developed by treatment with gamma-ray or proton irradiation in 14 sorghum cultivars. The levels of TPC and TFC of 14 original cultivars were ranging from 3.27 to 11.54 mg/100 g and 2.39 to 6.74 mg/100 g, respectively. The TPCs of the mutant lines were ranging from 1.92 to 13.10 mg/100 g with average content of 6.35 mg/100 g. The TFCs of the mutant lines were ranging from 1.72 to 8.30 mg/100 g with average content of 4.20 mg/100 g. Three mutant lines derived from gamma-ray showed significant lower TPC and TFC than those of the original cultivar. While, five mutant lines showed significant higher TPC and TFC. These findings will be useful for the selection of sorghum genotypes with improved phenolic compounds.

• Journal of Life Science
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• v.22 no.7
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• pp.863-870
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• 2012

Rhodopsin, a dim light photoreceptor, has been regarded as one of the model systems for the structural and functional study of G protein-coupled receptors (GPCRs). Constitutively active mutant GPCRs leading to the activation of heterotrimeric GDP/GTP-binding protein signaling in the absence of ligand binding are of interest for the study of the activation mechanism in GPCRs. The present study focused on the opsin mutant E134Q/M257Y, which showed a moderate level of constitutive activity and the formation of two distinct rhodopsin chromophores with absorption maxima of 500 nm and 380 nm, depending on the presence of an inverse agonist, 11-cis-retinal, and an agonist, all-trans-retinal, respectively. Reconstitution of the mutant rhodopsin upon incubation with different ratios of 11-cis-retinal and the all-trans-retinal, as well as upon sequential binding of the two retinals, indicated its preferential binding to 11-cis-retinal. The thermal stability of the 11-cis-retinal-bound form of the E134Q/M257Y mutant was lower than that of the mutants containing a single replacement but higher than that of the all-trans-retinal-bound forms. The mutant also showed a lower stability in its opsin state as compared with that of the wild-type opsin but had little effects on the binding affinity to 11-cis-retinal. Information obtained in this study will be helpful for analyzing the structural changes associated with the activation of rhodopsin and GPCRs.