• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.35-42
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• 2008

Vibrio vulnificus produces siderophores, low-molecular-weight iron-chelating compounds, to obtain iron under conditions of iron deprivation. To identify genes associated with the biosynthesis of siderophore in V. vulnificus MO6-24/O, we screened clones with mini-Tn5 random insertions for those showing decreased production of siderophore. Among 6,000 clones screened, nine such clones were selected. These clones contain the transposon inserted in VV2_0830 (GenBank accession number) that is a homolog of a nonribosomal peptide synthase (NRPS). There is an another NRPS module, VV2_0831, 49-bp upstream to VV2_0830. We named these two genes vvs (Vibrio vulnificus siderophore synthase) A and B, respectively. Mutation of either vvsA or vvsB showed a decreased production of siderophore. The expression of an NRPS-lux fusion was negatively modulated by the presence of iron, and the regulation was dependent on Fur (ferric uptake regulator). However, the expression of the NRPS genes was still not fully derepressed in the iron-rich condition, even in furnull mutant cells, suggesting that some other unknown factors are involved in the regulation of the genes. We also demonstrated that the NRPS genes are important for virulence of the pathogen in a mice model.

• BMB Reports
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• 제43권2호
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• pp.122-126
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• 2010

Homozygous staggerer ($RORa^{sg/sg}$) mice showed a severe ataxia caused by cerebellum degeneration. Decreased and dysfunctional Rora is a main cause of this neurologic phenotype. The phenotype of staggerer mice has been well known in cerebellum. However, there has been rarely reported about cerebrum even though of staggerer is expressed in merely cerebellum but hippocampus, thalamus, cortex, and olfactory bulb. The expressions of Ki67, doublecortin (DCX), and NeuN, which are cell proliferation, neuronal differentiation and mature neuron markers, respectively, were measured with immunohistechemistry in dentate gyrus in staggerer mice in order to uncover whether staggerer can affect the change in dentate gyrus. The immunoreactivities of DCX and NeuN were significantly reduced in the dentate gyrus of staggerer mice than normal control, while Ki67 were rarely unchanged in staggerer mice. These results suggest that staggerer mutation has an influence on the neuronal differentiation and development not only in cerebellum but also in dentate gyrus.

• KSBB Journal
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• 제25권2호
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• pp.199-204
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• 2010

Drag-tag으로 사용될 반복단위 단백질을 생물학적인 방법을 통해 생산함으로써 수용액 내에서 DNA 분리가 가능함을 확인하였다. 서로 다른 크기를 갖는 두 종류의 반복단위 단백질을 디자인하였고, 이를 발현시킨 뒤 정제하였다. 정제된 반복단위 단백질에 형광 dye를 포함하고 있는 100 base의 DNA를 연결하였고, 이 연결 물질을 모세관 내부가 수용액으로 충진된 microchip 상에서 전기영동 하였다. 그 결과 생물학적으로 생산된 반복단위 단백질이 SNP 분석과 같은 빠르고 효율적인 DNA 분석에 적합한 후보물질로 사용될 수 있음을 확인하였다.

• The Plant Pathology Journal
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• 제24권1호
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• pp.1-7
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• 2008

Fusarium verticillioides (teleomorph Gibberella moniliformis) is associated with maize worldwide causing ear rot and stalk rot, and produces fumonisins, a group of mycotoxins detrimental to humans and animals. While research tools are available, our understanding of the molecular mechanisms associated with fungal virulence and fumonisin biosynthesis in F. verticillioides is still limited. One of the restraints that hampers F. verticillioides gene characterization is the fact that homologous recombination (HR) frequency is very low (<2%). Screening for a true gene knock-out mutant is a laborious process due to a high number of ectopic integrations. In this study, we generated a F. verticillioides mutant (SF41) deleted for FvKU70, a gene directly responsible for non-homologous end-joining mechanism, with the aim of improving HR frequency. Here, we demonstrate that FvKU70 deletion does not impact key Fverticillioides phenotypes, e.g., development, secondary metabolism, and virulence, while dramatically improving HR frequency. Significantly, we also confirmed that a high percentage (>85%) of the HR mutant strains harbor a desired mutation with no additional copy of the mutant allele inserted in the genome. We conclude that SF41 is suitable for use as a type strain when performing high-throughput gene function studies in F. verticillioides.

• Journal of Microbiology and Biotechnology
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• 제26권12호
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• pp.2066-2075
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• 2016

In this study, an enhanced lipid-producing mutant strain of the microalga Chlamydomonas reinhardtii was developed by gamma irradiation. To induce the mutation, C. reinhardtii was gamma irradiated at a dose of 400 Gy. After irradiation, the surviving cells were stained with Nile red. The mutant (Cr-4013) accumulating 20% more lipid than the wild type was selected. Thin-layer chromatography revealed the triglyceride and free fatty acid contents to be markedly increased in Cr-4013. The major fatty acids identified were palmitic acid, oleic acid, linoleic acid, and linolenic acid. Random amplified polymeric DNA analysis showed partial genetic modifications in Cr-4013. To ascertain the changes of protein expression in the mutant strain, two-dimensional electrophoresis was conducted. These results showed that gamma radiation could be used for the development of efficient microalgal strains for lipid production.

• Journal of Korean Neurosurgical Society
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• 제62권3호
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• pp.272-287
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• 2019

The mechanistic target of rapamycin (mTOR) pathway coordinates the metabolic activity of eukaryotic cells through environmental signals, including nutrients, energy, growth factors, and oxygen. In the nervous system, the mTOR pathway regulates fundamental biological processes associated with neural development and neurodegeneration. Intriguingly, genes that constitute the mTOR pathway have been found to be germline and somatic mutation from patients with various epileptic disorders. Hyperactivation of the mTOR pathway due to said mutations has garnered increasing attention as culprits of these conditions : somatic mutations, in particular, in epileptic foci have recently been identified as a major genetic cause of intractable focal epilepsy, such as focal cortical dysplasia. Meanwhile, epilepsy models with aberrant activation of the mTOR pathway have helped elucidate the role of the mTOR pathway in epileptogenesis, and evidence from epilepsy models of human mutations recapitulating the features of epileptic patients has indicated that mTOR inhibitors may be of use in treating epilepsy associated with mutations in mTOR pathway genes. Here, we review recent advances in the molecular and genetic understanding of mTOR signaling in epileptic disorders. In particular, we focus on the development of and limitations to therapies targeting the mTOR pathway to treat epileptic seizures. We also discuss future perspectives on mTOR inhibition therapies and special diagnostic methods for intractable epilepsies caused by brain somatic mutations.

• Asian Pacific Journal of Cancer Prevention
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• 제17권9호
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• pp.4395-4399
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• 2016

The FLT3-ITD mutation is one of the most frequent genetic abnormalities in acute myeloid leukemia (AML) where it is associated with a poor prognosis. The FLT3-ITD mutation could, therefore, be a potential molecular prognostic marker important for risk-stratified treatment options. We amplified the FLT3 gene at exon 14 and 15 in 52 AML patients (aged between 2 months and 74 years) from 4 referral centers (a university hospital and 3 regional hospitals in Northeast Thailand), using a simple PCR method. FLT3-ITD mutations were found in 10 patients (19.2%), being more common in adults than in children (21.1% vs. 14.3%) and more prevalent in patients with acute promyelocytic leukemia (AML-M3) than AML-non M3 (4 of 10 AML-M3 vs. 6 of 42 AML-non M3 patients). Duplication sequences varied in size-between 27 and 171 nucleotides (median=63.5) and in their location. FLT3-ITD mutations with common duplication sequences accounted for a significant percentage in AML patients in northeastern Thailand. This simple PCR method is feasible for routine laboratory practice and these data could help tailor use of the national protocol for AML.

• Journal of Genetic Medicine
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• 제15권1호
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• pp.20-23
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• 2018

Point mutations in the human cardiac homeobox gene NKX2.5 are associated with familial atrial septal defect (ASD), atrioventricular (AV) conduction disturbance, as well as sudden cardiac death. To date, more than 60 NKX2.5 mutations have been documented, but there are no reports in Korea. We are reporting the first Korean family with ASD and AV block associated with a novel mutation in the NKX2.5 coding region. A 9-year-old boy presented with a slow and irregular pulse, and was diagnosed with secundum ASD and first degree AV block. The boy's father, who had a history of ASD correction surgery, presented with second degree AV block and atrial fibrillation. The boy's brother was also found to have secundum ASD and first degree AV block. There were two sudden deaths in the family. Genetic testing revealed a novel mutation of NKX2.5 in all affected members of the family.

• Journal of Microbiology and Biotechnology
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• 제18권11호
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• pp.1853-1857
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• 2008

Salmonella contamination in chicken meat was studied with 100 chicken meat samples purchased from 55 shops located in various regions. A total of 21 isolates of Salmonella enterica were isolated from 21 chicken meat samples from four shops located at open markets, whereas there were none from supermarkets with well-equipped cold systems. Among these, 18 isolates were identified as Salmonella enterica serotype Haardt (S. Haardt) and three isolates were S. enterica serotype Muenchen. When the minimal inhibitory concentrations of the S. Haardt isolates were assayed with the agar dilution method to determine susceptibility to ampicillin, chloramphenicol, sulfisoxazole, tetracycline, and nalidixic acid, all 18 isolates were resistant to tetracycline and nalidixic acid and nine of these were resistant to ampicillin. These isolates showed reduced susceptibility to eight fluoroquinolones including ciprofloxacin, enrofloxacin, levofloxacin, gatifloxacin, gemifloxacin, moxifloxacin, norfloxacin, and ofloxacin. When quinolone resistance determining regions of gyrA and gyrB were sequenced, every isolate had the same missense mutation Ser83$\rightarrow$Tyr (TCC$\rightarrow$+TAC) in gyrA, whereas no mutation was found in gyrB. Pulsed-field gel electrophoresis with XbaI revealed a close relationship among these isolates, suggesting a contamination of raw chicken meat with clonal spread of nalidixic acid-resistant and quinolone-reduced susceptibility S. Haardt in chickens. Results in this study show the importance of a well-equipped cold system and the prudent use of fluoroquinolone in chickens to prevent the occurrence of quinolone-resistant isolates.

• 한국생산제조학회지
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• 제8권1호
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• pp.67-73
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• 1999

This paper presents resizing design optimization method by utilizing genetic algorithm(GA), which consists of three basic operators : reproduction, crossover and mutation. The fitness and penalty function for resizing optimization problem are defined, and the flowchart of the developed computer program along with the descriptions of each modules is presented. Also, modelling for flexible-body dynamic analysis is presented. The model is composed of bodies, joints, and force elements such as translational spring-damper-actuator. The design objects si to determine the wall thickness for minimum weight under dynamic displacement constraint.