• Applied Biological Chemistry
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• v.37 no.2
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• pp.110-114
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• 1994

In searching for new insecticidal compounds from soil microorganisms, strains of streptomyces species showed insecticidal activities on Musca domestica and Bombyx mori were selected. Compounds I-IV, which were isolated from the metabolites of no. 46 strain, were identified as piericidin $C_1$, $C_2$, $C_3$ and $D_1$, respectively by UV and NMR data analyses.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.166-171
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• 2013

While high-dose ionizing radiation results in long term cellular cytotoxicity, chronic low-dose (<0.2 Gy) of X- or ${\gamma}$-ray irradiation can be beneficial to living organisms by inducing radiation hormesis, stimulating immune function, and adaptive responses. During chronic low-dose-rate radiation (LDR) exposure, whole body of mice is exposed to radiation, however, it remains unclear if LDR causes changes in gene expression of the whole brain. Therefore, we aim to investigate expressed genes (EGs) and signaling pathways specifically regulated by LDR-irradiation ($^{137}Cs$, a cumulative dose of 1.7 Gy for total 100 days) in the whole brain. Using microarray analysis of whole brain RNA extracts harvested from ICR and AKR/J mice after LDR-irradiation, we discovered that two mice strains displayed distinct gene regulation patterns upon LDR-irradiation. In ICR mice, genes involved in ion transport, transition metal ion transport, and developmental cell growth were turned on while, in AKR/J mice, genes involved in sensory perception, cognition, olfactory transduction, G-protein coupled receptor pathways, inflammatory response, proteolysis, and base excision repair were found to be affected by LDR. We validated LDR-sensitive EGs by qPCR and confirmed specific upregulation of S100a7a, Olfr624, and Gm4868 genes in AKR/J mice whole brain. Therefore, our data provide the first report of genetic changes regulated by LDR in the mouse whole brain, which may affect several aspects of brain function.

• Smart Structures and Systems
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• v.16 no.3
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• pp.415-433
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• 2015

Tendon failures in bonded post-tensioned bridges over the last two decades have motivated ongoing investigations on various aspects of unbonded tendons and their monitoring methods. Recent research shows that change of strain distribution in anchor heads can be useful in detecting wire breakage in unbonded construction. Based on this strain variation, this paper develops a damage detection model that enables an automated tendon monitoring system to identify and locate wire breaks. The first part of this paper presents an experimental program conducted to study the strain variation in anchor heads by generating wire breaks using a mechanical device. The program comprised three sets of tests with fully populated 19-strand anchor head and evaluated the levels of strain variation with number of wire breaks in different strands. The sensitivity of strain variation with wire breaks in circumferential and radial directions of anchor head in addition to the axial direction (parallel to the strand) were investigated and the measured axial strains were found to be the most sensitive. The second part of the paper focuses on formulating the wire breakage detection framework. A finite element model of the anchorage assembly was created to demonstrate the algorithm as well as to investigate the asymmetric strain distribution observed in experimental results. In addition, as almost inevitably encountered during tendon stressing, the effects of differential wedge seating on the proposed model have been analyzed. A sensitivity analysis has been performed at the end to assess the robustness of the model with random measurement errors.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.447-452
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• 1999

The role of bacteria in root canals and periapical infections is well known and established. In these bacteria, black-pigmented bacteria(BPH) play important role in endodontic infection. BPB are Gram negative anaerobic rods which are closely related 50 clinical symptoms such as pain, percussion, tenderness, foul odor, etc. In America and Europe, many studies on BPB have been done and are continued. But, relatively few studies have been done in Korea, especially its prevalence in Korean population is not yet studied. The purpose of this study is to establish prevalence of BPB in infected root canals and periapical abscesses in Korean people. Microbial samples were collected from the root canals of 34 intact tooth with periapical rarefactions of endodontic origin and 3 periapical abscesses. All samples were incubated in an anaerobic chamber(Coy, Model No. 77. Ann Arbor, Michigan, USA.). Identification of In microorganism was based on its growth in the anaerobic chamber, colonial pigmentation, colonial morphology, Gram stain, and Rapid ID32A(BioMericux SA/69280 Marcy-l'Etoile/France) results. In addition, the polyme ase chain reaction using specific primers for 16S rRNA genes were used differentiate Prevotella nigrescens for Prevotella intermedia. The results were as follows : 1. In this study, thirteen (35%) of thirty seven samples were positive for the growth of BPB. In thirteen samples, sixteen strains of BPR were found. 2. The most frequently identified BPB in root canals and abscesses in Korean were P. nigrescens 5/37(14%) and P. intermedia 5/37(14%). Porphyromonas gingivalis 3/37(8%), Porphyromonas endodontalis 2/37(5%) and Prevotella loecheii 1/37(3%) were also found. 3. In this study, no significant differences were found between the prevalence of BPB in Korean and that of American and European.

• Journal of Life Science
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• v.20 no.3
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• pp.321-325
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• 2010

Among endogenous oral microflora, Streptococcus mutans plays a critical role in dental plaque formation, which mainly contributes to the development of caries and periodontal disease. Phytochemicals are plant-derived chemical compounds that have been studied as beneficial nutrients to human health. The purpose of this study was to determine the effects of phytochemicals against S. mutans. Among them, oleanolic acid (OA) and 5-(hydroxymethyl)-2-furfural (HF) from Thomson seedless raisins were tested for anti-microbial effects against various clinically important bacteria. OA inhibited the growth of Gram-positive bacteria, but not Gram-negative bacteria. However, HF did not display any antibacterial effect against any of the strains tested. OA also exhibited inhibitory effects in surface adherence and biofilm formation of S. mutans. The results suggest that OA can be utilized as a potential anti-plaque and anti-caries agent by controlling the physiological characteristics of S. mutans on teeth.

• Korean Journal of Microbiology
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• v.36 no.2
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• pp.103-108
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• 2000

We have cloned and analyzed cDNA coding for non-virion (NV) protein of the m V - P R T The NV gene contained 336 bp open readmg frame and encoded a protein of 11 1 amino acids with a molecular weight of 13.2 kDa. The deduced amino acid sequence of NV of IHNVPRT was found to be 90-95% identical to those of foreign isolates of IHNV. These results indicate that NV gene of the MNV is highly conserved among &ifferent strains of THNV Northern blot analyses revealed that the levels of NV gene expression were strongly elevated after 20 h post-infection. In order to identify the role of NV in the replication of MNV in fish cells, IHNVinfected cells were treated with antisense oligonucleotides. While IHNV-PRT exposed to glycoprotein (G) antisense oligonucleotide showed severely reduced growth, the growth of virus exposed to NV antisense oligonucleotide was not affected by NV antisense oligonucleotide, which suggests that NV is not essential for replication of IHNV in fish cells.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.279-286
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• 1991

In order to investigate the possibility of the microbial degradation of the persistent pollutant 3, 3', 4, 4'-tetrachloroazobenzene (TCAB) in our environment, four strains of microorganisms were isolated from industrial wastes by the enrichment technique. They were identified as Achromobacter group VD, Pseudomonas alcaligenes, Moraxella spp., and Alcaligenes faecalis, respectively. These microorganisms utilized TCAB as a sole carbon source in the $MM_2$ salt medium.

• Microbiology and Biotechnology Letters
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• v.39 no.3
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• pp.287-293
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• 2011

The purpose of this study was to isolate and characterize fungal deteriogens, which induce discoloration of the cement tunnel, and calcite forming bacteria (CFBs), which have antifungal activity against fungal deteriogens. Isolation of mold, bacteria and yeast was performed using several solid media and partially identified using internal transcribed spacer (ITS); 5.8S rRNA gene sequencing and 16s rDNA sequencing. A total of 19 microbial strains were identified with the most widely distributed fungal strain being Cladospirum sphaerospermum. In addition, five bacteria derived from the tunnel were identified as CFBs. Amongst the latter, Bacillus aryabhatti KNUC205 exhibited antifungal activity against Cladospirum sphaerospermum KNUC253 and Aspergillus niger KCTC6906 as concentrated filtered supernatants.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.293-296
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• 2014

This study was conducted to investigate the effect of culture temperature on the growth rate and protease activity of Antarctic microorganisms. The Antarctic microorganisms PAMC 25641, 25614, 25719 and 25617 were obtained from the Polar and Alpine Microbial Collection (PAMC) at the Korea Polar Research Institute. These microorganisms were confirmed for the excretion of protease on a plate with skim milk. The identification of microorganisms was carried out using the 16S rDNA sequencing method. PAMC 25641 showed the highest protease activity among the subjects tested, and PAMC 25617 exhibited the highest growth rate. The growth rates of the microorganisms were not affected by temperature, except for PAMC 25617. However, protease activities were increased for all strains in a temperature dependent fashion. These results suggest the possible application of Antarctic microorganisms for the efficient production of low temperature proteases.

• Korean journal of applied entomology
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• v.15 no.2 s.27
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• pp.61-68
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• 1976

Leading soybean cultivars such as Kwanggyo, Yugu No.3, Dongbugtae, Gangrim, and Eundaedu were heavily diseased by a virus in Korea. The disease was most severe in the northern provinces where soybean mosaic virus also occurrs, but the disease has also been observed in other provinces where soybean diseases are less prevalent. The disease symptoms were similar to bud blight caused by tobacco ringspot virus; but this was not confirmed in inoculation tests on indicator plants and serological experiments. There were some differences in varietal susceptibility to the disease, with symptom variation depending on the soybean cultivar and source of inoculm. Disease symptoms on infected soybean plants were mottling and necrosis. The present results, therefore, indicate some strains of SMV or a mixture of legume viruses may or may not be responsible for the disease.