• Korean Journal of Microbiology
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• 제41권2호
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• pp.146-151
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• 2005

To construct an amylolytic industrial strain of Saccharomyces cerevisiae, the glucoamylase cDNA gene (GAl) from Aspergillus awamori was expressed under the control of the alcohol dehydrogenase gene promoter (ADC1p) and integrated into the chromosomes of industrial S. cerevisiae. An integrative cassette lacking bacterial ampicillin resistance gene but containing the GA1 gene, $\delta$ sequences of Ty1 retrotransposon as target sites for homologous recombination and S. cerevisiae aureobasidin A resistance gene (AUR1-C) as the selection marker was constructed to obtain a strain eligible for commercial use. Industrial S. cerevisiae transformed with this 15-integrative cassette efficiently secreted glucoamylase into the medium and grew on starch as the sole carbon source. The transformants were mitotically stable for 100 generations in nonselective medium.

• Journal of Life Science
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• 제20권5호
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• pp.789-793
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• 2010

Artificial chromosome manipulation and amplification of single-copy yeast artificial chromosome (YAC) are usually required in order to use YACs for applications such as physical mapping and functional analysis in eukaryotes. We designed and implemented a Simultaneous YAC Manipulation-Amplification (SYMA) system that combines the copy number amplification system of YAC with a convenient YAC manipulation system. To achieve the desired split and to amplify a YAC clone-harboring plant chromosome, a pBGTK plasmid containing a conditional centromere and thymidine kinase (TK) gene was constructed as a template to amplify the splitting fragment via PCR. By splitting, new 490-kb and 100-kb split YACs containing the elements for copy number amplification were simultaneously generated from a 590-kb YAC clone. The 100-kb split YAC was then successfully amplified 14.4-fold by adding 3 mg/ml sulfanilamide and $50\;{\mu}g/ml$ methotrexate (S3/M50) as inducing substances.

• Journal of Microbiology
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• 제43권4호
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• pp.354-360
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• 2005

Heat-labile enterotoxin B subunit (LTB) of enterotoxigenic Escherichia coli (ETEC) is both a strong mucosal adjuvant and immunogen. It is a subunit vaccine candidate to be used against ETEC-induced diarrhea. It has already been expressed in several bacterial and plant systems. In order to construct yeast expressing vector for the LTB protein, the eltB gene encoding LTB was amplified from a human origin enterotoxigenic E. coli DNA by PCR. The expression plasmid pLTB83 was constructed by inserting the eltB gene into the pYES2 shuttle vector immediately downstream of the GAL1 promoter. The recombinant vector was transformed into S. cerevisiae and was then induced by galactose. The LTB protein was detected in the total soluble protein of the yeast by SDS-PAGE analysis. Quantitative ELISA showed that the maximum amount of LTB protein expressed in the yeast was approximately $1.9\%$ of the total soluble protein. Immunoblotting analysis showed the yeast-derived LTB protein was antigenically indistinguishable from bacterial LTB protein. Since the whole-recombinant yeast has been introduced as a new vaccine formulation the expression of LTB in S. cerevisiae can offer an inexpensive yet effective strategy to protect against ETEC, especially in developing countries where it is needed most.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.148.2-149
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• 2003

Cucumber fruit mottle mosaic tobamovirus (CFMMV) causes severe mosaic symptoms with yellow mottling on leaves and fruits, and occasionally severe wilting of cucumber plants. No genetic source of resistance against this virus has been identified. The genes coding for the coat protein or the putative 54-kDa replicase were cloned into binary vectors under control of the SVBV promoter. Agrobacterium-mediated transformation was peformed on cotyledon explants of a parthenocarpic cucumber cultivar with superior competence for transformation. R1 seedlings were evaluated for resistance to CFMMV infection by lack of symptom expression, back inoculation on an alternative host and ELISA. From a total of 14 replicase-containing R1 lines, 8 exhibited immunity, while only 3 resistant lines were found among a total of 9 CP-containing lines. Line 144 homozygous for the 54-kDa replicase was selected for further resistance analysis. Line 144 was immune to CFMMV infection by mechanical and graft inoculation, or by root infection following planting in CFMMV-contaminated soil. Additionally, line 144 showed delay of symptom appearance following infection by other cucurbit-infecting tobamoviruses. Infection of line 144 plants with various potyviruses and cucumber mosaic cucumovirus did not break the resistance to CFMMV. The mechanism of resistance of line 144 appears to be RNA-mediated, however the means is apparently different from the gene silencing phenomenon. Homozygote line 144 cucumber as rootstock demonstrated for the first time protection of a non-transformed scion from soil inoculation with a soil borne pathogen, CFMMV.

• Journal of Life Science
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• 제15권3호
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• pp.317-322
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• 2005

The cycloinulooligosaccharide fructanotransferase (CFTase) gene (cft) from Paenibacillus macerans was subcloned into an E. coli-yeast shuttle vector, pYES2.0, resulting in pYGECFTN. The plasmid pYGECFTN (8.6 kb) was introduced into Saccharomyces cerevisiae SEY2102 cells and then the transformants were selected on the synthetic defined media lacking uracil. The cft gene expression in yeast transformant was demonstrated by the analyses cyclofructan (CF) spots on thin-layer chromatogram. The recombinant CFTase was not secreted into the medium and localized in the periplasmic space. The production of CF was observed after 5 min of the enzymatic reaction with inulin. The optimun pH and temperature for CF production were found to be at pH 8.0 and $45^{\circ}C$, respectively. Enzyme activity was stably maintained up to $55^{\circ}C$. The CF was produced from all inulin sources and was most efficiently produced from dahlia tubers and Jerusalem artichokes.

• Journal of Life Science
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• 제23권7호
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• pp.863-868
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• 2013

The XylP gene, which encodes endoxylanase in Bacillus sp. HY-20, was subcloned, and two expression plasmids, pG-xylP and pGMF-xylP were constructed. These plasmids, which contain different signal sequences, XylP s.s and $MF{\alpha}_{opt}$ s.s, respectively, for the secretory expression of endoxylanase, were transformed into Saccharomyces cerevisiae SEY2102 and FY833, respectively. The recombinant endoxylanases were successfully expressed, with a total activity range of 23.7-70.1 unit/ml according to the expression system and host strain. The endoxylanase activity in SEY2102/pGMF-xylP reached a maximum of 88.1 unit/ml in baffled flask culture. Most of the recombinant endoxylanase was efficiently secreted in the extracellular fraction, and the $MF{\alpha}_{opt}$ s.s was more efficient for secreting endoxylanase in yeast than the XylP s.s. Therefore, the expression system developed in this study produces large extracellular amounts of endoxylanase using S. cerevisiae as the host strain, and it could be used in bioethanol production and industrial applications.

• Proceedings of the Korean Society of Toxicology Conference
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• 한국독성학회 2000년도 국제심포지움 및 추계학술대회
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• pp.45-67
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• 2000

2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a mutagenic and carcinogenic heterocyclic amino found in cooked meat. The in vivo mutagenicity and hepatocarcinogenicity of MeIQx were examined in mice harboring the lacZ mutation reporter gene ($Muta^{TM}$ Mice) and bitransgenic mice over-expressing the c-myc oncogene. C57B1/$\lambda$lacZ and bitransgenic c-myc (albumin promoter)/$\lambda$lacZ mice were bred and weaned onto an AIN-76 based diet containing $0.06\%$ (w/w) MeIQx or onto control diet. After 30 weeks on diet, only male bitransgenic mice on MeIQx developed hepatocellular carcinoma ($100\%$ incidence) indicating that there was synergism between c-myc over-expression and MeIQx. By 40 weeks, hepatic tumor incidence was $100\%$ ($17\%$) and $44\%$ ($0\%$) in male c-myc/$\lambda$lacZ and C57B1/$\lambda$lacZ mice given MeIQx (or control) diet, respectively, indicating that either MeIQx or c-myc over-expression alone eventually induced hepatic tumors. At either time point, mutant frequency in the lacZ gene was at least 40-fold higher in MeIQx-treated mice than in control mice of either strain. These findings suggest that MeIQx-induced hepatocarcinogenesis is associated with MeIQx-induced mutations. Elevated mutant frequency in MeIQx-treated mice also occurred concomitant with the formation of MeIQx-guanine adducts as detected by the $^{32}P$-postlabeling assay. Irrespective of strain or diet, sequence analysis of the lacZ mutants from male mouse liver showed that the principal sequence alteration was a single guanine-base substitution. Adenine mutations, however, were detected only in animals on control diet. MeIQx-fed mice harboring the c-myc oncogene showed a l.4-2.6-fold higher mutant frequency in the lacZ gene than mice not carrying the transgene. Although there was a trend toward higher adduct levels in c-myc mice, MeIQx-DNA adduct levels were not significantly different between c-myc/$\lambda$lacZ and C57B1/$\lambda$lacZ mice after 30 weeks on diet. Thus, it appeared that factors in addition to MeIQx-DNA adduct levels, such as the enhance rate of proliferation associated with c-myc over-expression, may have accounted for a higher mutant frequency in c-myc mice. In the control diet groups, the lacZ mutant frequency was significantly higher in c-myc/$\lambda$lacZ mice than in 057B1/$\lambda$1acZ mice. The findings are consistent with the notion that c-myc over-expression is associated with an increase in mutagenesis. The mechanism for the synergistic effects of c-myc over-expression on MeIQx hepatocarcinogenicity appears to involve an enhancement of MeIQx-induced mutations.

• Journal of Chest Surgery
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• 제30권9호
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• pp.899-907
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• 1997

Recently, primary lung cancer has increased markedly in incidence & prevalence in korea. Prom July 1979 to June 1996, 183 patients were diagnosed and operated for primary non-small cell lung cancer, and evaluated clinically. 1. There were 164 males and 19 females(M:P=8.6: 1), and the peak incidence of age was 50th and 60th decade of life(73.7%). 2. Most of symptoms were respiratory, whitch were cough(44.8%), chest pain(30.1%), dyspnea(20.8%), hemoptysis or blood tinged sputum(19.7%), sputum(15.3%), and asymptomatic cases were 12.0%. 3. Histopathologically, sguamous cell carcinoma was 68.9%, adenocarcinoma 19.7%, bronchioloalveol r cell carcinoma 2.2%, adenosguamous cell carcinoma 1.6%, and large cell carcinoma 7.7%. 4. In the operation, pneumonectomy was 41.0%, lobectomy 42.1%, bilobectomy 13.1%, stagmentectomy or wedge resection 1.6%, and explore tharacotomy 2.2%, and the overall resectability was 97.8%. 5. Postoperative complications were developed in 31.9%, and operative mortality was 1.6%. 6. In postoperative stagings, stage I was 38.3%, stage H 14.8%, stage llla 31.1%, and stage IIIb 15.8%. 7. The overall cumulative survival rates were 1 year 77.8%, 3 year 42.7%, and 5 year 39.5%. The 5 year survival rate according to stage were stage 153.0%, stage H 46.5%, stage I[la 28.2%, and stage IIIb 13.8%(p<0.05), according to operation method were lobectomy 45.0%, and pneumonectomy 30.3%(p<0.05), and according to mediastinal involvement were Nl 32.0%, and N2 11.1%(p<0.05). The 5 year survival rate according to histologic type were squamous cell carcinoma 43.1%, adenocarcinoma 23.3%, and large cell carcinoma 30.3 (p>0.05).