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Differential responses of Expressed Antioxidative Enzyme between Anoxic and Aerobic Conditions
Woo-Jae Kim,Jong-Cheol Ko,Man-Kee Baek,Ki-Yong Ha,Ji-Young Son,Mun-Sik Shin,Jae-Kweon Ko 한국작물학회 2008 한국작물학회 학술발표대회 논문집 Vol.2008 No.10
Rice seeds germinate in the complete absence of oxygen. Under anoxia, the seeds have greater stress in abiotic condition than in aerobic one. Antioxidant enzymes play an important role of ROS(Reactive Oxygen Species) scavenging in various anoxic stress. We investigated the relationship between antioxidant enzymes and early seedling growth of four rice cultivars (Iksan 429, Khaiyan, FR13A, and Nampyeong) under anoxic and aerobic conditions. Rice seeds immersed into a sealed water bottle for 10 days. During anoxia, rates of cleoptile elongation were faster in tolerant varietise Iksan 429 and Khaiyan than in FR13A and Nampyeong. In the anoxic water condition, the activity of SOD in Iksan 429 and Khaiyan increased slightly until 5 days , while that of Nampyeong and FR13A decreased significantly after 7 days. The activity of peroxidase in Khaiyan was higher than that of FR13A. These results suggest that the ability to increase SOD and POX may be one of the determinants in anoxia tolerance of rice.
Jae Kweon Park,Mi Ja Chung,Ha Na Choi,Ju Hee Ko,Hye Ran Moon,Yong Il Park 한국당과학회 2011 한국당과학회 학술대회 Vol.2011 No.1
Effects of the degree of deacetylation (DDA) and the molecular mass of chitosan oligosaccharides (CTS-OS), obtained from the enzymatic hydrolysis of high molecular weight chitosan (HMWC), on antitumor activity was explored. The DDA and molecular weights of CTS-OS were determined by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-TOF MS) analysis. The CTS-OS were found to be a mixture of mainly dimers (18.8%), trimers (24.8%), tetramers (24.9%), pentamers (17.7%), hexamers (7.1%), heptamers (3.3%), and octamers (3.4%). The CTS-OS were further fractionated by gel-filtration chromatography into two major fractions: (1) COS, consisting of glucosamine (GlcN)n, n = 3–5 with DDA 100%; and (2) HOS, consisting of (GlcN)5 as the minimum residues and varying number of N-acetylglucosamine (GlcNAc)n, n = 1 –2 with DDA about 87.5% in random order. The cytotoxicities, expressed as the concentration needed for 50% cell death (CC50), of CTS-OS, COS, and HOS against PC3 (prostate cancer cell), A549 (lung cancer cell), and HepG2 (hepatoma cell), were determined to be 25 mg∙mL-1, 25 mg∙mL-1, and 50 mg∙ mL-1, respectively. The HMWC was approximately 50% less effective than both CTS-OS and COS. These results demonstrate that the molecular weight and DDA of chitosan oligosaccharides are important factors for suppressing cancer cell growth.
Ju Hee Ko,Jae Kweon Park,Woo Jung Kim,Hang Soo Jo,Yong Il Park 한국당과학회 2010 한국당과학회 학술대회 Vol.2010 No.1
A chitinolytic enzyme from the culture filtrates of Pseudomonas fluorescens was purified to apparent homogeneity and its kinetic properties were characterized. The molecular weight of the purified enzyme (NagA) was estimated by SDS–PAGE to be approximately 50 kDa. The optimum pH, temperature, and pH stability of NagA on synthetic substrate pNP-GlcNAc were determined to be pH 6.5, 37oC and pH 6–9, respectively. Its kinetic parameters on pNP-GlcNAc and pNP-(GlcNAc)2 were Km = 0.13 mM and 0.82 mM, and Vmax = 245 and 40 pmol/㎍/min, respectively. Chitinolytic activity of the purified NagA toward natural substrates (GlcNAc)n, n=2-5 was also determined by high performance anion-exchange chromatography with pulsed electrochemical detection (HPAEC-PED). The results suggest that NagA is an exo-type β-N-acetylglucosaminidase yielding GlcNAc as the final product from the chitooligosaccharides. Taken together, this is the first report of an exo-type chitinolytic enzyme based on the comparison of its peptide sequence from other chitinolytic enzyme produced by other microorganisms.
정재권(Chung Jae-Kweon),고은(Ko Un) 한국재활심리학회 2002 재활심리연구 Vol.9 No.1
The purpose of this research is to approach sexuality of a person with developmental disabilities as one of their rights by emphasizing the importance of sexual education of a person with mental retardation and also by introducing to the public the regulations with regards to a person with mental retardation as well as the sexuality implemented in Germany at the same time. In addition, the methodological approach on sexual education was reviewed for better educational effects, and several programs which can be used on-site regarding recognition of body parts , one of sexual education themes, was introduced as well. In a view that sexual behavior of human beings is not a natural legacy but the product of social · cultural education process. the sexual education for a person with developmental disabilities should be handled as a synthetical part of total education process with great importance. And, legal regulators as well as parents of a person with developmental disabilities, consultants, educators, and care-takers at the times in which we live should take more aggressive actions for those with developmental disabilities to fully develop and live with their sexuality within the scope recognized from the society and culture we live in.
Yang, Hyungjun,Ko, Hyun-Jeong,Yang, Jin-Young,Kim, Jae-Jin,Seo, Sang-Uk,Park, Seung Gu,Choi, Sun Shim,Seong, Je Kyung,Kweon, Mi-Na University of Chicago Press 2013 The Journal of infectious diseases Vol.207 No.1
<P>Interleukin (IL)-1 is a well-known cytokine for the initiation of innate immunity in bacterial infection. However, the underlying mechanism of IL-1 on the respiratory infection is not fully elucidated. We studied how IL-1 contributes to the host defense against Streptococcus pneumoniae. IL-1R(-/-) mice showed high mortality, local cytokine storm, and substantial infiltrates in the lower respiratory tract after intratracheal challenge with S. pneumoniae. The IL-1-deficient condition did not suppress the propagation of bacteria in the lung, although the recruitment and the bacteria-killing ability of neutrophils (CD11b(+)Ly6C(+)Ly6G(+)) were not defective compared with wild-type mice. Unexpectedly, we found that the transcription of fibrinogen alpha and gamma genes were highly activated in the lungs of wild-type mice after the infection, whereas no significant changes were found in IL-1R(-/-) mice. Of note, synthesis of fibrinogen was dependent on the IL-1-IL-6-Stat3 cascade. Treatment with recombinant fibrinogen improved survival and bacterial propagation in the IL-1R(-/-) mice and blockade of the coagulation increased the susceptibility of wild-type mice to pneumococcal pneumonia. Our findings suggest that IL-1 signaling leads to the synthesis of fibrinogen in the lung after pneumococcus infection and is followed by coagulation, which contributes to the control of bacterial infection in the pulmonary tract.</P>
정종운,김재건,고태조,김희술,박종권 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-
Micro/meso cutting is getting more important in the fields of precision machining technology. A micro-turning lathe is one of parts to consist the Micro Factory. It accepts stepwise motion actuators that are used for feeding system instead of the conventional mechanism. It is consisted of two Piezoelectric ceramics; one is for feeding the slider, and the other is for clamping the slider in the guide way of the body. The linearity and positional accuracy of the actuators are good enough for high precision motion. The spindle unit is operated with DC motor on the top of the slider. The motion is communicated with miniaturized linear encoder attached on each side of axis. A mono crystal diamond tool is used for cutting tool. This micro-lathe has been made a machining experiment to see the characteristics of micro-machining.
Estimation of Current Decay Performance of HTS Electromagnet for Maglev
Chang Young Lee,Jung Min Jo,Young Jae Han,Duck Kweon Bae,Yong Soo Yoon,Sukjin Choi,Dong Keun Park,Tae Kuk Ko IEEE 2010 IEEE transactions on applied superconductivity Vol.20 No.3
<P>This paper deals with the estimation of current decay rates resulting persistent current mode (PCM) performance and its affect on design of high temperature superconducting (HTS) coil models used in an HTS electromagnet. The HTS coil models were designed to generate the required magneto motive force(MMF) on HTS electromagnets operating at various levitation gaps. We simulated the current decay rate with the self-inductance and joint resistance of the superconducting coil. The current decay rates of the models for the 10 mm levitation gap were in the range of 4.5% to 18%, whereas current decay rates of the models for the 25 mm levitation gap were in the range of 2.2% to 5.3%. It was found that the HTS electromagnet for large levitation gaps had more advantages than those for narrow air gaps in regards to designing an HTS coil with better PCM performance.</P>
Giant Zeeman splitting in nucleation-controlled doped CdSe:Mn<sup>2+</sup> quantum nanoribbons
Yu, Jung Ho,Liu, Xinyu,Kweon, Kyoung Eun,Joo, Jin,Park, Jiwon,Ko, Kyung-Tae,Lee, Dong Won,Shen, Shaoping,Tivakornsasithorn, Kritsanu,Son, Jae Sung,Park, Jae-Hoon,Kim, Young-Woon,Hwang, Gyeong S.,Dobro Nature Publishing Group 2010 Nature Materials Vol.9 No.1
Doping of semiconductor nanocrystals by transition-metal ions has attracted tremendous attention owing to their nanoscale spintronic applications. Such doping is, however, difficult to achieve in low-dimensional strongly quantum confined nanostructures by conventional growth procedures. Here we demonstrate that the incorporation of manganese ions up to 10% into CdSe quantum nanoribbons can be readily achieved by a nucleation-controlled doping process. The cation-exchange reaction of (CdSe)<SUB>13</SUB> clusters with Mn<SUP>2+</SUP> ions governs the Mn<SUP>2+</SUP> incorporation during the nucleation stage. This highly efficient Mn<SUP>2+</SUP> doping of the CdSe quantum nanoribbons results in giant exciton Zeeman splitting with an effective g-factor of ∼600, the largest value seen so far in diluted magnetic semiconductor nanocrystals. Furthermore, the sign of the s–d exchange is inverted to negative owing to the exceptionally strong quantum confinement in our nanoribbons. The nucleation-controlled doping strategy demonstrated here thus opens the possibility of doping various strongly quantum confined nanocrystals for diverse applications.