• Archives of Pharmacal Research
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• v.18 no.4
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• pp.243-248
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• 1995

Seventeen transformation-deficient mutants of streptococcus pneumoniae, which are defective in competence induction (com), DNA uptake(ent) of recombination(rec), were investigated to determine sensitivity to ethylmethane sulfonate(EMS), methylmethane sulfonate(MMS), UV and mitomycin C. In ethylmethane sulfonate assay, the viability of most $com^-, \; rec^-\; and ent^-$ mutants was decreased about 2-10 times and the viability of ent-9 and ent-13 mutant was decreased about 33 and 25 times, respectively. On the other hand only half of the transformation-deficient mutants tested was sensitive to methylmethane sulfonate about 2 times and ent-12 mutant was sensitive to 2.0% MMS about 8 times. After UV and mitomycin C treatment, most of the mutants are not sensitive to UV and mitomycin C, although the viability of some transformation-deficient mutants was decreased slightly. Especially none of the com mutants were sensitive to DNA damage suggesting that competence is not involved in DNA repair. Also DNA uptake and recombination gane might be related to DNA repair function.

• YAKHAK HOEJI
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• v.36 no.6
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• pp.582-590
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• 1992

S. pneumoniae recP mutant was compared with rec-8 mutant to identify whether they are the same gene or not by determining sensitivity to DNA damaging agents. recP and rec-8 mutant have almost same sensitivity to UV, ethylmethane sulfonate, and methylmethane sulfonate, suggesting that recP has the same function as the rec-8 gene in DNA repair.

• Microbiology and Biotechnology Letters
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• v.30 no.1
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• pp.68-72
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• 2002

To obtain a yeast mutant with high RNA content and high growth rate, Saccharomyces cerevisiae MTY62 was mutated with ethylmethane sulfonate. Among the selected mutants that were sensitive to the high concentration of KCl, M40-10 strain was finally selected due to its rapid cell growth and high RNA content in the tube and baffled-flask cultures. In the batch culture of M40-10 mutant, the maximum specific growth rate ($\mu_{max}$) of $0.38 h^{-1}$ , RNA concentration of 3210 mg-RNA/1, and RNA content of 183 mg-RNA/g-DCW were obtained, which were 23%, 15%, and 12% increased levels, respectively, compared to those of MTY62 parent strain. The intermittent fed-batch culture of M40-10 strain resulted in the maximum cell concentration of 35.6 g-DCW/1, RNA concentration of 5677 mg/1, and RNA content of 160 mg-RNA/g-DCW. Through the constant fed-batch culture, the maximum cell concentration of 46.4 g-DCW/1, RNA concentration of 6270 mg-RNA/1, and RNA content of 135 mg-RNA/g-DCW were obtained. At the 20 h culture time in the fed-batch cultures of M40-10 strain, the cell and RNA concentrations were increased by 30% and 10%, respectively, over the parent strain MTY62. In addition, it was also found that the accumulated RNA within the mutant cell was not degraded until the end of fed-batch cultivation, indicating that the M40-10 cell is a mutant with weak acidic RNase activity.y.

• Journal of Life Science
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• v.9 no.1
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• pp.22-25
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• 1999

In order to study the mechanism for the adaptation to salt stress, we mutagenized budding yeast Saccharomyces cerevisiae with Ethylmethane sulfonate, and isolated salt-tolerant mutants. Among the salt-tolerant mutants, two strains exhibit additional temperature sensitive phenotype. Here, we report that these two salt-tolerant mutants are specific to {TEX}$Na^{+}${/TEX} rather than general osmotic stress. These mutant strains may contain mutations in the genes involved in {TEX}$Na^{+}${/TEX} home-ostasis.

• The Korean Journal of Food And Nutrition
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• v.13 no.2
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• pp.158-163
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• 2000

Killer yeast, Hansenular capsulata S-13 were treated with heat, ethylmethane sulfonate and N-methyl-n'-nitro-n-nitrosoguanidine and a mutant(S13-E1), showing 2-fold higher killer toxin activity than that of parent strain to killer sensitive strain, Saccharomyces cerevisiae ATCC 38026 was obtained. Hansenular capsulata S13-E1 showed strong killer toxin activity to Saccharmyces mellis and Saccharomyces sal년 and four strains of gas-producing yeasts from traditional Doenjang and Kochujang. The culture condition for killer toxin production by Hansenular capsulata S13-E1 was optimized to be 1.0% potato extract, each 0.5% of peptone and glucose, and 0.025% MgSO4 with initial pH 4.5 at 3$0^{\circ}C$ and 36 hr of batch cultivation.

• Journal of Life Science
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• v.12 no.6
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• pp.715-720
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• 2002

A mutant Arabidopsis thaliana which is very sensitive to Ultraviolet-B(UV-B) radiation has been isolated by ethylmethane sulfonate(EMS) mutagenesis. Genetic cross proved the UV-sensitive gene(uvs) to segregate as a single Mendelian locus. For mapping of uvs, we crossed Arabidopsis thaliana Lansberg with uvs plant(Columbia), and made F2 plants by F1 selfcross. We designed 10 kinds of CAPS marker primers. Each primers amplifies a single mapped DNA sequence from uvs and Lansberg erecta ecotyres. Also identified was at least one restriction endonuclase for each of these PCR product that generates ecotype-specific digestion pattern. We got crossing over value of UB-sensitivity and each CAPS marker which located on different chromosome arm. The value of crossing over showed that uvs was linked to LFY3 which was on chromosome 5.

• Journal of Microbiology and Biotechnology
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• v.1 no.3
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• pp.151-156
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• 1991

In order to construct a yeast strain having high ethanol tolerance together with good lactose fermentation ability, the protoplast fusion using Saccharomyces cerevisiae STV 89 and Kluyveromyces fragilis CBS 397 was carried out. Auxotrophic mutants of K. fragilis were obtained as a selection marker by treatment of ethylmethane sulfonate. The best mutant for protoplast fusion was selected based on the capabilities of ${\beta}-galactosidase$ production and lactose fermentation. The protoplast fusion using polyethylene glycol and calcium chloride solution led to the fusion frequence of $3{\times}10^{-6}$ and a number of fusants were obtained. Among these fusants, a fusant F-3-19 showed the best results in terms of ethanol tolerance, ${\beta}-galactosidase$ activity and lactose fermentation. The performance of lactose fermentation and ethanol tolerance by this fusant were better than those of K. fragilis. Study on the ethanol tolerance having relation to fatty acid composition and intracellular ethanol concentration revealed that the fusant F-3-19 had a higher unsaturated fatty acids content and accumulated less amount of intracellular ethanol compared with a parent of K. fragilis.

• Journal of Crop Science and Biotechnology
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• v.11 no.2
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• pp.119-126
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• 2008

Since somatic embryogenesis combined with ethylmethane sulfonate(EMS) treatments is the most efficient technique for mutagenesis, the embryogenic capacity of four soybean cultivars was evaluated at different EMS concentrations, treatment times, and preculture durations. Two to 4 mm long immature cotyledons were placed in induction medium after EMS treatment, and the numbers of somatic embryos formed per explant were counted four weeks after culture initiation. We observed genotypic differences in the efficiency of somatic embryogenesis from immature embryos among four cultivars treated with different concentrations of EMS for six hours. Cultivars, Sinpaldalkong 2 and Jack, displayed highly efficient somatic embryogenesis regardless of EMS concentration, whereas very low efficiency or no survival was observed in Jinju 1 and Iksannamulkong cultivars. Preculture duration did not influence the efficiency of somatic embryogenesis. Because Sinpaldalkong 2 exhibited the best somatic embryogenesis, much higher concentrations of EMS were used to test somatic embryo formation under different periods of time in this cultivar. Three and six hour treatments with both 1 and 2 mM EMS yielded higher embryo formation than longer periods of time. Increasing the time with embryos in 2 mM EMS caused a reduction in somatic embryogenesis in Sinpaldalkong 2, but many chlorophyll-deficient soybean variants were identified in the $M_1R_0$ and $M_2R_1$ generations. In addition to Jack, Sinpaldalkong 2 is a good genotype for plant regeneration from EMS-treated immature embryo cultures.

• Korean Journal of Food Science and Technology
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• v.20 no.2
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• pp.164-169
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• 1988

Protoplast susion between Zygosaccharmoyces rouxii M-12 and Saccharimyces cerevusuare M-43 were investigated for breeding of a new brewing yeat strain for soy sauce. Auxotrophic mutants of Zygosaccharomyces rouxii ZRM-83 ($Met^-,\;Thr^-$) and Saccharomyces cerevisiae SCM-46 ($Lys^-,\;Arg^-$) were selected by treatment of 3.0% ethylmethane sulfonate and nutritional complementary method. Protoplast of both strains were more effective by treatment of 0.05mg/ml zymolase 20T for 60min. Fusion effeciency was much higher by treatment of 30% PEG 6,000 for 30min and fusion frequencies were $10^{-4}{\sim}10^{-5}$. These fusants originated from two protoplasts had properties of big cell size and much DNA content.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.465-474
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• 1999

RNase activity of Saccharomyces cerevisiae ATCC 7754 was investigated to obtain strains with high ribonucleic acid (RNA) content. The yeast strain contained two RNase activities; an acidic RNase with a optima of pH $3{\sim}4$ and an alkaline RNase with a optima pH 9. The acidic RNase activity was inhibited by $0.08\;M\;HgCl_{2}$ most drastically. The alkaline RNase activity was inhibited by 2.0 M NaCl or KCl, while enhanced by addition of $0.05\;M\;CaCl_{2},\;0.02\;M\;ZnSO_{4},\;or\;0.008\;M\;HgCl_{2}$. Various mutants of Saccharomyces cerevisiae ATCC 7754 were isolated by ethylmethane sulfonate (EMS) treatment or $\gamma$-ray/ultra violet irradiation. Among the mutants that were sensitive to high concentration of KCl which inhibits alkaline RNase, B24 was selected for high RNA content per culture volume. Growth characteristics of the mutant were comparable to those of the mother strain with optimum growth at pH $4.5{\sim}5.5$. The mutant accumulated higher content of RNA than the mother strain when glucose was used as the carbon source. However, both growth rate and total RNA content of the mutant were higher in molasses medium than in glucose medium. RNA content of the mutant increased rapidly during the early stage of growth, and then decreased gradually until the culture reached stationary phase by a fed-batch culture in a 5 L jar fermenter. Maximal cell harvest and the final RNA content using the mutant B24 were 69.6 g/L culture broth and 19.8 g/100 g of the dry cell while those using the mother strain were 68 g/L culture broth and 16.1 g/100 g of dry cell, respectively.