• Journal of Plant Biology
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• v.30 no.1
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• pp.69-77
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• 1987

From the single cell cultures of haploid tobacco (Nicotiana tabacum L. cv. NC 2326) glyphosate-resistant plants were regenerated. After treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and then inoculated onto the LS medium supplemented with 1 mM glyphosate, the single cells survived formed colonies and calluses in 65 and 95 days after culture, respectively, and then whole plants were regenerated in 0.1 mM glyphosate-containing medium from the selected calluses. There was no difference in fresh weight and shikimate content between the selected and normal haploid calluses. When sprayed with 0.1 mM glyphosate, the shikimate contents in the regenerated and normal plants were 0.659 and 20.816 mol/g fr. wt., while that in other normal plants which were not sprayed was 0.921. In addition, the calluses induced from the regenerated plants grew without showing any retardation when treated with glyphosate. These results indicate that the secelcted calluses and regenerated plants are resistant to glyphosate.

• Korean Journal of Microbiology
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• v.29 no.2
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• pp.123-129
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• 1991

In order to develop the protoplast fusion method of the strains of Fusarium, the interspecific protoplast fusion was attempted between Fusarium poae and F. sporotrichioides. Various auxotrophic mutants were isolated by the treatment of N-Methyl-N'-Nitro-N-Nitrosoguanidine. The optimal conditions for the formation and regeneration of protoplasts were examined and the characteristics of a fusant were studied. As a results, protoplasts were readily obtained from 18 hours cultured mycelia by the treatment of driselase for 3 hours and 0.6 M KCl as a best osmotic stabilizer at pH 6.0 for the formation of protoplast. Sucrose was the most suitable for the regeneration. Polyetylene glycol (M.W. 8,000) in $CaCl_{2}$-glycine solution was used to induce the protoplast fusion. The interspecific fusion frequency between protoplasts among the auxotrophic mutants of the two strains ranged from $2.7*10^{-2}$ to $5.7*10^{-3}$ . DNA content and cellulase activity were rather increased in the interspecific fusant. The lag phase of growth curve was slightly elongated in the fusant.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.122-127
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• 1991

A bacterial strain NO. 32 which produced thermostable ${\alpha}$-amylase was isolated from soil and identified to genus of Bacillus. To enhance ${\alpha}$-amylase productivity, a successive mutation of Bacillus sp. No. 32 was attempted with treatment of N-methyl-N'-nitro-N-nitrosoguanidine (NTG). The resulting mutant, Bacillus sp. No. 32H417, which is risistant to refampicin and deficient in spore formation, produced about 90-fold high level of ${\alpha}$-amylase when compared with parental strain. The properties of the enzyme for thermostability were investigated. The optimal temperature and pH for enzyme reaction were 95$^{\circ}C$ and pH6.5, respectively, in the presence of 0.3mM $Ca^{2+}$ as an effective stabilizer.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.325-325
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• 1994

본 연구에서는 먼저 14종의 flavonoid화합물을 대상으로 발암물질로서 잘 알려져있는 benzo(a)pyrene[B(a)P]에 대한 소핵생성억제효과를 관찰하였다. 소핵시험을 이용한 유전독성억제실험에서 비적적 큰 활성을 보이는 flavonoid는 2,3 이중결합과 3,5,7-trihydroxyl기를 갖는 polyhydroxy flavonol화합물들이었다. 이중에서 galangin은 활성이 비교적 컸으며, 이같은 유전독성억제효과는 galangin투여시 B(a)P의 대사활성화가 감소되고 활성본태산물들의 DNA binding을 저해함으로서 나타났다. 한편, galangin은 대사활성화가 필요없는 1차 발암물질인 N-methyl-N'-nitro-N-nitrosoguanidine(MNNG)에 의한 소핵생성도 감소시켰다. 이러한 galangin의 alkylating agent에 대한 유전독성억제효과는 calf thymus DNA를 이용한 실험에서 DNA의 메칠화를 저해하는 기전으로 나타나는 것으로 판단되었다. galangin은 mitouycin과 같은 DNA cross-linking agent에 의한 소핵생성에도 억제효과를 나타내었다. 특히 동시투여(simultaneous treatment)나 사후투여(post-treatment)시보다 사전투여(pre-treatment)시에 소핵생성억제효과가 컸으며 사전연속투여(multiple Pre-treatment)시에는 낮은 용량에서도 효과가 컸다. 이러한 저용량의 사전연용투여에 의한 유전독성억제효과들은 B(a)P나 MNNG에 대해서도 잘 나타났다.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.581-584
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• 2019

In this study, the carbon monoxide (CO)-fermenting acetogen, Clostridium sp. AWRP was subjected to chemical mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) to generate a CO-resistant mutant. Among the 26 colonies obtained, the highest alcohol production was observed in one isolate, named C1. Compared to the wild-type strain, the C1 strain exhibited 1.5- and 3.4-fold higher CO consumption rate and alcohol selectivity, respectively. The total CO consumption of strain C1 could be further enhanced by increasing the content of metal ions, such as nickel and iron. The highest ethanol titer (5.7 g/l) was achieved by 5-fold increase in the iron concentration.

• Korean Journal of Microbiology
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• v.17 no.3
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• pp.137-151
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• 1979

Germinating conidia of Aspergillus nidulans diploid heterozygous for color and other genetic markers were used to direct and distinguish genetic events such as mutation, mitotic crossingover and nondisjunction in a single test after treatment with N-methyl-N'-nitro-N-nitrosoguanidine (NG), mitomycin C(MC), and chloral hydrate(CH). The following results were obtained : 1. NG reduced the survival of conidia and increased the frequencies of miototic segregants about sevenfoli over the control ; among the mitotic segregants the predominant genetic event was mitotic crossingover. NG also produced many abnormal colonies, which appeared to be of the types caused by induced semidominant lethals or chromosomal aberrations, and the aneuploid types found spontaneously. 2. After treatment with MC the survival of conidia was reduced but few abnormal colonies were produced. The frequencies of miotic segregants were increased about threefold over the control ; in the mitotic segeregants the induced genetic event was mitotic crossingover. 3. CH gave no apparent effect on the survival of conidia and the frequencies of mitotic segregants. However, CH generated abnormal colonies, very greatly, which turned out to be of the aneuploid types. This result suggests that CH interferes with the normal distribution of chromosomes in mitosis.

• YAKHAK HOEJI
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• v.35 no.4
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• pp.253-257
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• 1991

The anti-mutagenic effect of Orostachys japonicus (OJ) toward aflatoxin (AFB$_{1}$) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the Salmonella assay system was studied. The methanol extract of OJ inhibited the mutagenicity induced by AFB$_{1}$ about 97% when 5% of the extract added to the system. Butanol fraction from the methanol extract was the most effective against AFB$_{1}$. However, other fractions of hexane, chloroform, and ethylacetate also showed considerable antimutagenic activity against AFB$_{1}$. Several identified compounds from the fractions of OJ exhibited anti-mutagenic effect. $\beta$-Sitosterol, astragalin and kaempferol-3-rhamnosyl-7-glucoside were selected from the compounds, and these compounds inhibited the mutagenicity dose-dependently. These 3 compounds also decreased the mutagenicity induced by MNNG. From these results, it is suggested that the major compounds such as triterpene, sterol and flavonoid in the OJ were responsible for the inhibition of the AFB$_{1}$ and MNNG-induced mutagenicities.

• Preventive Nutrition and Food Science
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• v.2 no.1
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• pp.29-34
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• 1997

In order to determine the effectiveness of linoleic acid(LA) to inhibit carcinogens/mutagens-induced mu-tagenesis, Ames test using Salmonella typhimurium TA100 and the SOS chromotest using E. Coli PQ37, were carried out. The inhibitory effect of LA(1%) on the Ames mutagenicity test were 98%, 78%and 69% mediated by aflatoxin B₁(AFB₁), N-methyl-N'-nitro-N-nitrosoguanidine(MNNG) and 4-nitroquinoline-1-oxide(4-NQO), respectively. LA exhibited a strong antimutagenic activity aganist indirect mutagen, AFB₁whereas exhibited the same concentration of LA showed weaker inhibitory effects on direct mutagens of MNNG and 4-NQO than that AFB₁. LA also reduced the SOS responses induced by MNNG and 4-NQO significantly. This result showed a possibility that LA can be a protective agent in early step of cancinogenesis.

• 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.

• YAKHAK HOEJI
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• v.43 no.1
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• pp.124-127
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• 1999

Bifidobacterium infantis K-525 isolated from healthy Korean was susceptible to rifampicin and fluoroquinolones and resistant to other antituberculosis agents. When the preparation of this strain is taken as a therapeutics for human intestinal disorders with rifampicin or fluoroquinolones, its therapeutic effect can not be expected. So, B, infantis RFR-525 resistant to rifampicin was obtained by treating the parent B. infantis 525 with N-methyl-N'-nitro-N-nitrosoguanidine. B. infantis OFR-525 was produced by serial passage of B. infantis RFR-525 on agar with 2-fold minimal inhibitory concentration of ofloxacin. B. infantis OFR-525 was resistant to antituberculosis agents and fluoroquinolones up to 4∼128 fold higher than that for the original strain. The resistance of B. infantis OFR-525 against rifampicin and ofloxacin was maintained in vivo and in vitro. Conclusively, B. infantis OFR-525 can be regarded as a promising strain which can be developed as the preparation for the treatment of the intestinal disorders of the tuberculosis patients under rifampicin and ofloxacin therapy.