• 미생물학회지
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• 제26권1호
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• pp.20-26
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• 1988

Three $NIf^{-}$ -mutants were isolated from Enterbacter agglomerans 339 through the transposon umtagenesis using a RP4-mobilising system for its nif-gene characterization. All mutants hadn't acetylene-reduction ability. Then we confirmed that Tn5 was inserted into all conserved nif-plasmids through the Southern Hybridization.

• 미생물학회지
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• 제37권1호
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• pp.28-36
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• 2001

본 연구에서는 세포주기의 Gl/S기에 관련된 유전자의 작용기작을 이해하기 위하여 출아효모인 Saccharomyces cerevisiae를 사용하여 세포주기 진행 및 조절에 관련된 변이주를 분 리하여 특성화하는 연구를 수행하였다. 먼저 새로운 변이주를 분리하기 위해서 HeLa 세포와 출아효모에서 Gl을 유발하는 CPO(ciclopirox olamine) 약제에 대해 감수성을 보이는 변이주를 선별하였다. 그 결과, 총 31개의 CPO에 대한 감수성 변이주들이 분리되었고, ciclopirox olamine sensitivity의 첫 글자를 따서 con mutants라 명명하였다. cos 변이주들의 표현형의 특성을 결정하기 위해 MMS(methylmethane sulfonate)와 HU(hydrsxyurea)에 대한 감수성을 조사하여 그 성질에 따라 4개의 group으로 나누었다. Group I에는 cos27, cos28, cos32, cos33, cos36, cos37, cos40, cos42, cos46, cos50, cos52, cos53 변이주가 포함되고, 이들은 MMS와 HU 두 약제 모두에 대해서 감수성을 보여 S기 checkpoint에 관련된 것으로 보이고, Group II는 cos43, cos48 변이주로 MMS에 대해서 감수성을 지녀 G1기 또는 G2기 checkpoint에 관련된 것으로 추측된다. Group III 변이주에는 cos35, cos47, cos54, cos55, cos56이 포함되고 HU에 대해서 감수성을 보여 S기에 관련된다고 보여지며, Group IV 변이 주는 cos29, cos30, cos31, cos34, cos38, cos39, cos41, cos44, cos45, cos49, cos51, cos57로서 단지 CPO에 대해서만 감수성을 나타냈다. 더욱이 변이주의 최종표현형을 형광현미경을 이용하여 조사하여, S기 checkpoint에 관련된 것으로 보이는 cos37 변이주를 확인하였다. 또한, 변이주와 야생주의 이형접합체인 이배체를 만들어 변이주의 유전학적 분석을 수행하였다.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.144.1-144
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• 2003

Attenuated viruses can protect their hosts against challenge to their related viruses. Increasing evidence shows that mutations of the tobamoviral 126/183 kDa protein play a major role in the viral attenuation and contribute to the cross protection mechanism. In this study, four mutants of Pepper mild mottle virus (PMMoV) have been constructed by mutagenesis; two mutants, pTPpoly348 and pTPpoly762, were substituted in the middle of replicase gene, and the others, pTPL3D:: $\Delta$6207 and pTPL3D:: $\Delta$6219, were deletion mutants made by deleting some parts of pseudoknot structures of the 3' noncoding region (NCR) of the virus. Progeny viruses generated from the four mutants were infectious on N. benthamiana plants with symptomless or mild mosaic symptom. Replication efficiency and viral product accumulations of four mutants were assessed by Northern and Western blot analyses on BY-2 protoplast cells. Accumulation of CP for the pTPL3D:: $\Delta$6207 and pTPL3D:: $\Delta$6219 were lower than that of other mutants and wild type virus. These data suggest that the 3'-NCR mutations contribute to the viral gene expression in host tissues, while mutants of replicase gene rather govern the symptom expression.

• 아시안잔디학회지
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• 제11권1호
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• pp.45-58
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• 1997

Pigments and thylakoid membrane proteins were investigated in wild type and PS I- mutants from Synechocystis sp. PCC6803 Comparing morphological features, B2 was less fluorescent than the other strains. The contents of chlorophyll a were propotional to the FNR activity in thylakoid membrane. The FNR activity of mutants was lower than that of wild type. In the result of pigments analysis, mutants had smaller cholophyll a than that of wild type. The major carotenoid was found to he $\beta$-caroene, but aeaxanthin was barely detected in thylakoid membrane of mutants. The polypeptide, 14.8kD was detected by electrophoresis in mutants. It was considered to be the modification of 15.4kD in wild type. Membrane polypeptides of 17.6 and 19.7kD were not detected in mutants. In the result of western blotting, subunit I was detected in all strains, but subunit II was barely detected in mutants. Subunit II was not detected in B2 at all. In view of the results so far achieved, the changes of contents of chlorophyll and zeaxanthin were affected by the defficiency or modification of functional domain in subunit I. Also the modification in subunit I affected the subunit II- binding site in PS I. As the result, efficiency of photosynthesis was decreased. Key words: Synechoystis sp. PCC6803, PS I - mutant, Photosynthetic efficiency, Pigment,Thylakoid membrane proteins, Subunit I, II.

• 대한임상검사과학회지
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• 제37권3호
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• pp.173-177
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• 2005

YMDD motif mutants of the hepatitis B virus(HBV) emerge in chronic hepatitis B patients after prolonged lamivudine treatment. HBV DNA breakthrough may be accompained by the emergence of YMDD mutants. We compared the performance of the sequencing method with that of RFMP method in chronic hepatitis B patients who had suffered the HBV DNA breakthrough after lamivudine treatment. Both sequencing and RFMP methods were used to detect YMDD variants in 20 chronic hepatitis B patients. YMDD mutants were detected in 17 samples (85.0%) by both methods. Among them, no mutants were detected in two samples(10.0%), while they were detected in the other sample(5.0%) with the RFMP method. The concordance rate between both methods was 95.0%. There was inconsistency in one sample showing mutants detected by the RFMP method, but not by sequencing method. In the sequencing method, the mutants was detected in the major type virus, but not in the minor type virus. However, both sequencing and RFMP methods were highly concordant except in one sample, so it is suggested that both methods are useful to detect YMDD mutants of chronic hepatitis B patients.

• 한국육종학회지
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• 제40권2호
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• pp.113-118
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• 2008

This study was carried out to investigate the chemical composition of peanut mutants induced by gamma radiation (Co-60) at 300 Gy in seeds of the cultivar Shinnamkwang. The protein contents of twenty-eight peanut mutants ranged from 23.3% to 31.7% and were increased by from 0.5% to 8.4% in fifteen mutants lines from the 26.8% of the original variety, cv. Shinnamkwang. Lipid contents of in mutants ranged from 43.2% to 53.5%, an increase of 0.2% to 5.7% from the 47.8% of the original variety. The range of unsaturated oleic acid in 28 mutants was from 38.9% to 56.9% an increase of from 1.3% to 14.0% from the 50.6% in the original variety. Linoleic acid, the highest unsaturated fatty acid, constituted 32.6% meanly of mutants, it was 17.4% lesser than oleic acid, ranging from 25.9% to 42.0%. Palmitic acid (16:0) contents ranged from 8.6% to 11.1%, and the mutant line-9 had the highest content. The ratio of oleic to linoleic acid was 0.9 to 2.2. A negative coefficient (r=-0.98**) was obtained between oleic and linoleic acid, but for other fatty acids, no significant relation was observed. Similarly, a negative coefficient of r=-0.68**was observed between saturated and unsaturated acids. The sucrose compositions of mutants ranged from 2.6% to 6.2%.

• 한국자원식물학회지
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• 제25권6호
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• pp.745-752
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• 2012

Compared to wide ranges of genetic variation of natural populations, very limited Miscanthus cultivar has been released. This study was the first report on the development of Miscanthus cultivar by means of radiation breeding. Seeds of M. sinensis were initially exposed to gamma rays of 250 Gy for 24 h, generated from a $^{60}Co$ gamma-irradiator. The irradiated seeds were sown and then the highly tiller-producing mutants were selected for this study. Biomass-related parameters including tiller number, plant height, stem diameter, and leaf number were measured. Ploidy level and internal transcribed spacer (ITS) were investigated to characterize the mutants compared to wild type (WT) Miscanthus. Plant height and tiller number were negatively related, where multi-tillering mutants were relatively short after 4 month growth. However stem diameter and leaf number were greater in mutants. All the materials used in this study were diploid, implying that the mutants with greater tiller numbers and stem diameter were not likely related to polyploidization. Based on the sequence of ITS regions, the mutants demonstrated base changes from the gamma irradiation where G+C content (%) was decreased in the ITS1, but increased in ITS2 when compared to WT sequence. ITS2 region was more variable than in ITS1 in the mutants, which collectively allows identification of the mutants from WT. Those mutants having enhanced tillers and allelic variations might be used as breeding materials for enhanced biomass-producing Miscanthus cultivars.

• Journal of Crop Science and Biotechnology
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• 제11권1호
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• pp.31-38
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• 2008

Improvement of $N_2$ fixation by symbiotic rhizobia is considered an effective means for enhancing its productivity without high input of nitrogen(N) fertilizer. Several methods to improve $N_2$ fixation have been proposed including the use of supernodulating mutants. The objective of this research was to identify the varietal difference in N and $N_2$-fixation ability among the soybean supernodulating mutants, SS2-2 and Sakukei 4, with different nodulation abilities using $^{15}N$ in field conditions in both Korea and Japan. The dry weight(DW) was higher in wild-type soybeans. The distribution rate of DW in each plant part was high in seeds of supernoduating and wild-type soybeans but high in stems and leaves of non-nodulating mutants. Although the supernodulating mutants had a low DW rate at maturity, they showed a similar $N_2$ fixation ability compared with wild-type. Supernodulating mutant plants mainly obtained N from $N_2$ fixation, while soil N was the main resource for obtaining N in non-nodulating mutants. The percentage of N derived from atmospheric dinitrogen(Ndfa) was higher in supernodulating mutants than in wild-type and relatively high in seeds between plant parts at maturity. In particular, supernodulating mutants showed higher N content in roots than those of wild-type and non-nodulating mutants. It was considered that supernodulating mutants have the advantage of saving nitrate in soil and being beneficial for N absorption of subsequent crops due to their conserving more N in the field and releasing considerable amounts of N from roots and leaves fallen to the soil.

• Journal of Microbiology and Biotechnology
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• 제6권2호
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• pp.110-115
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• 1996

Yellow mutants of the astaxanthin producing red yeast Phaffia rhodozyma were obtained by nitrosoguanidine mutagenesis. The carotenoid composition of the yelow mutants, Yan-1 and Ny-1, was mainly $\beta$ -carotene (> 95$%$) and torulene (< 5$$). Therefore, the yellow mutants are carotene oxygenation deficient mutants (CODMs). CODMs produced decreased quantities of carotenoids compared to their red parents and this indicated that carotene may regulate its synthesis. CODMs, Yan-1 and Ny-4, on plates containing 50 $\mu$ M antimycin, showed highly pigmented vertical papillae. Antimycin-induced mutants purified from the papillae showed increases in carotenoid content (up to 1 mg $\beta$-carotene/g yeast). CODMs, Yan-1 and Ay-1, were more sensitive to antimycin than red strains, Ant-1 and 67-385. This was probably due to lower antioxidant activity of $\beta$-carotene than that of astaxanthin. Light increased torulene and light+antimycin further increased the torulene. Yan-1 and Ny-4 could grow with succinate, though their red parents, Ant-1 and Anf-1p, could not. However, antimycin induced mutation of Yan-1 or Ny-4 destroyed the ability to grow with succinate.

• BMB Reports
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• 제41권3호
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• pp.248-253
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• 2008

Stresses and nutritional starvation are two main external signals for the induction of sex pheromones in the fission yeast Schizosaccharomyces pombe. In an attempt to identify the components involved in transduction of starvation signals, we screened 135 temperature-sensitive (ts) mutants and isolated 6 mutants that induced the pheromone even in the presence of a nitrogen source. These mutants exhibited two distict induction phenotypes: pheromone induction at restrictive but not at permissive temperatures; and pheromone induction at both permissive and restrictive temperatures. The times required for the maximum pheromone induction at the restrictive temperature differed slightly in each mutant. In addition to the pheromone induction phenotype, the ts243 and ts304 mutants exhibited cell-division-cycle defects. The ts304 mutant cells showed an abnormal cytoplasmic DAPI staining pattern. The nucleolus of this mutant seemed to be fragmented, a phenomenon which is typically observed in aged yeast cells. The result of our genetic analysis indicated that the pheromone induction mutants belonged to 6 separate complementation groups. We designated these mutants pws1 to pws6.