• Molecules and Cells
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• v.24 no.2
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• pp.185-193
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• 2007

Symbiotic nitrogen fixation with nitrogen-fixing bacteria in the root nodules is a distinctly beneficial metabolic process in legume plants. Legumes control the nodule number and nodulation zone through a systemic negative regulatory system between shoot and root. Mutation in the soybean NTS gene encoding GmNARK, a CLAVATA1-like serine/threonine receptor-like kinase, causes excessive nodule development called hypernodulation. To examine the effect of nts mutation on the gene expression profile in the leaves, suppression subtractive hybridization was performed with the trifoliate leaves of nts mutant 'SS2-2' and the wild-type (WT) parent 'Sinpaldalkong2', and 75 EST clones that were highly expressed in the leaves of the SS2-2 mutant were identified. Interestingly, the expression of jasmonate (JA)-responsive genes such as vspA, vspB, and Lox2 were upregulated, whereas that of a salicylate-responsive gene PR1a was suppressed in the SS2-2 mutant. In addition, the level of JA was about two-fold higher in the leaves of the SS2-2 mutant than in those of the WT under natural growth conditions. Moreover, the JA-responsive gene expression persists in the leaves of SS2-2 mutant without rhizobia infection in the roots. Taken together, our results suggest that the nts mutation increases JA synthesis in mature leaves and consequently leads to constitutive expression of JA-responsive genes which is irrelevant to hypernodulation in the root.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.59-69
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• 2014

One of the major challenges in metabolic engineering for enhanced synthesis of value-added chemicals is to design and develop new strains that can be translated into well-controlled fermentation processes using bioreactors. The aim of this study was to assess the influence of various fed-batch strategies in the performance of metabolically engineered Pseudomonas putida strains, ${\Delta}gcd$ and ${\Delta}gcd-pgl$, for improving production of medium-chain-length polyhydroxyalkanoates (mcl-PHAs) using glucose as the only carbon source. First we developed a fed-batch process that comprised an initial phase of biomass accumulation based on an exponential feeding carbon-limited strategy. For the mcl-PHA accumulation stage, three induction techniques were tested under nitrogen limitation. The substrate-pulse feeding was more efficient than the constant-feeding approach to promote the accumulation of the desirable product. Nonetheless, the most efficient approach for maximum PHA synthesis was the application of a dissolved-oxygen-stat feeding strategy (DO-stat), where P. putida ${\Delta}gcd$ mutant strain showed a final PHA content and specific PHA productivity of 67% and $0.83g{\cdot}l^{-1}{\cdot}h^{-1}$, respectively. To our knowledge, this mcl-PHA titer is the highest value that has been ever reported using glucose as the sole carbon and energy source. Our results also highlighted the effect of different fed-batch strategies upon the extent of realization of the intended metabolic modification of the mutant strains.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.350-356
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• 2017

We previously reported that the CopA3 peptide (LLCIALRKK, ${\small{D}}-form$) originally isolated from the Korean dung beetle has antimicrobial and immunosuppressive effects. However, the high cost of producing the synthetic peptide, especially the ${\small{D}}-form$, has limited the development of CopA3 for therapeutic purposes. Here, we investigated whether the CopA3 deletion derivative, CopA5, which is composed of only five amino acids (LLCIA) and has the ${\small{L}}-form$ structure, could inhibit the lipopolysaccharide (LPS)-induced activation of macrophages. Peritoneal exudate macrophages (PEM) were isolated from mice and exposed to LPS in the presence or absence of CopA5, and biomarkers of macrophage activation were measured. Our results revealed that LPS-induced nitric oxide (NO) production, tumor necrosis factor $(TNF)-{\alpha}$ secretion, and phagocytic activity of PEM were significantly inhibited by CopA5 treatment. Similar to CopA3, the structurally modified CopA5 peptide had no cell toxicity (as assessed by measurement of cell viability loss and apoptosis) in PEM. Moreover, the LPS-induced upregulation of the activating phosphorylation of signal transducer and activator of transcription 1 (STAT1) was markedly inhibited by CopA5 treatment. These results suggest that, similar to CopA3, CopA5 inhibits macrophage activation by inhibiting STAT1 phosphorylation and blocking the release of NO and $TNF-{\alpha}$. CopA5 may therefore prove therapeutically useful in the realm of immune suppression.

• Journal of architectural history
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• v.20 no.1
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• pp.61-75
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• 2011

This study aims to investigate the changing aspects about research methodology of stone pagoda from the period of Japanese colonial to now. There were the differences in purpose, method and analysis of the research according to each period. In Japanese colonial period, the purpose of research was to make lists of almost stone pagodas in Korea. Following this, Japanese researchers conducted detailed research for academic purpose. They took measurements of stone pagodas and made drawings. After liberation the research was focused on the relics contained in pagodas. They proceeded to investigate the inner relics in order to attract the attention of the people. In the late 1900's, the repair works of cultural heritages were increased. Many reports of the repair works were released and sent to administration offices. The reports contained the change aspects of situation between before work and after with drawings or simple investigation documents. In the 1990's, the restoration works for important stone pagodas were started by the National Research Institute of Cultural Heritage. Since then, researches from various way - architectural and conservational researches about historical interpretation, shape, structure, proportion, technique, etc. - progressed for careful restoration and accurate study. In Recent years, various professional organizations(in the field of structure, physics, chemistry, biology, lithology, etc.) started to join the researches. Researches conducted studies directly with the stone pagodas, as well as conducting indirect studies with the stone pagodas, such as the structural stability of stone pagodas, the characteristics of rock, and conservation chemicals. Today the research project 'The preservation project of stone cultural property' is being conducted by the National Research Institute of Cultural Heritage. The purpose of this project is to gain more detailed and accurate investigation documents to be provided for the people. In conclusion, researches from various fields must be included in the research. Furthermore, a synthetic study should be done through comparing similar characteristics or different characteristics among many research results.

• Korean Journal of Microbiology
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• v.2 no.1
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• pp.1-11
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• 1964

Yung Nok Lee (Dept. of Biology, Korea University) : Studies on the phosphate metabolism in Chlorella, with special reference to polyphosphate. Kor. J. Microbiol., Vol.2, No.1, p1-11 (1964). 1. Uniformly $^{32}P$-labeled Chlorella cells which were irradiated with Cobalt-60 gamma-rays of about 70, 000 $\gamma$ dose, were further grown in a standard "cold" medium ("hot".rarw."cold"), and some portions of the algae were taken out at the begining of, and at intervals during the culture, and subjected to analyze the contents of $^{32}P$- and total P in various fractions of the cell materials. Results obtained were compared with those of nonirradiated normal cells. 2. Amounts of phosphate in various fractions of the nonirradiated normal Chlorella cells were measured using uniformly $^{32}P$--labeled cells. Analysis of the $^{32}P$--labeled algal cells showed that the highest value in P-content was the fraction of RNA followed by those of lipid, polyphosphate "C" polyphosphate "B", DNA, nucleotidic labile phosphate compounds, polyphosphate "A" and protein. It was observed that content of total polyphosphates in a single Chlorella cell was almost equal to RNA-P content in the cell, and the amount of RNA-P was almost equal to ten times of DNA-P content. 3. When the $^{32}P$--labeled algae which were irradiated with gamma-rays were grown in a normal "cold" medium, phosphate contents in the fraction of DNA, nucleotidic labile phosphate compounds and protein decreased markedly, while the contents of phosphate in the fractions of polyphosphate "C" and potyphosphate "B" increased in comparison with those of unirradiated normal cells. So, it was considered that the pretreatment of above mentioned dose of gamma-ray inhibited DNA and protein synthesis from polyphosphate in Chlorella cells. 4. Proceeding the culture of $^{32}P$--labeled Chlorella in a "cold" standard medium, whose synthetic activity of DNA and protein from polyphosphate was disturded by gamma-ray irradiation, the amounts of $^{32}P$-in the fraction of polyphosphate "C" increased, in contrast with those of polyphosphate "B" fraction. According to these experimental results, it was inferred that polyphosphate "B" could transform into polyphosphate "C" in normal growing Chlorella cells.sults, it was inferred that polyphosphate "B" could transform into polyphosphate "C" in normal growing Chlorella cells.ing Chlorella cells.

• The Korean Journal of Zoology
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• v.32 no.2
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• pp.153-162
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• 1989

Expedments were perfonned to examine the role of cAMP-dependent protein kinase (PK-A) and diacylglycerol-dependent protein kinase (PK-C) during the meiodc resumption and the first mitotic cell cycle of mouse embryogenesis. Mejoric GV oocytes and one-cell embryos derived from in vitro fertilization were cultured in vitro, and morphological changes in response to activators of PK-A and PK-C were examined. Treatments with a membrane-permeable cAMP analog, dbcAMP (0.1 mg/mi), phosphodiesterase inhibitor, IBMX (0.1 mM), biologically active phorbol ester, WA (10 nglmi), or a synthetic diacylglycerol, sn-diC8 inhibited resumption of melosis. Combination of PK-A and PK-C activator brought about furiher inhibition. On the contrary, dbcAMP (0.1 mg/mi), IBMX (0.2 mM), WA (10 nglml), and sn-diC8 (0.5 mM) did not inhibit pronucleus membrane breakdown (PNBD) when added S or G2 phase of cell cycle. However, activators of PK-C inhibited cleavage of one-cefl embryos. This result indicates that the action mechanism of PK-A and PK-C on dissolution of nuclear membrane in primary meiotic arrest oocytes may be different from that of mitotic one-cell embryos.

• Molecules and Cells
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• v.22 no.3
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• pp.328-335
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• 2006

Imperatoxin A ($IpTx_a$), a 3.7 kDa peptide from the African scorpion Pandinus imperator, is an agonist of the skeletal muscle ryanodine receptor (RyR1). In order to study the structure of the toxin and its effect on RyR1, $IpTx_a$ cDNA was PCR-amplified using 3 pairs of primers, and the toxin was expressed in E. coli. The toxin was further purified by chromatography, and various point mutants in which basic amino acids were substituted by alanine were prepared by site-directed mutagenesis. Studies of single channel properties by the planar lipid bilayer method showed that the recombinant $IpTx_a$ was identical to the synthetic $IpTx_a$ with respect to high-performance liquid chromatography mobility, amino acid composition and specific effects on RyR1. Mutations of certain basic amino acids ($Lys^{19}$, $Arg^{23}$, and $Arg^{33}$) dramatically reduced the capacity of the peptide to activate RyRs. A subconductance state predominated when $Lys^8$ was substituted with alanine. These results suggest that some basic amino acid residues in $IpTx_a$ are important for activation of RyR1, and that $Lys^8$ plays an important role in regulating the gating mode of RyR1.

• Molecules and Cells
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• v.27 no.2
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• pp.217-223
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• 2009

Development of symbiotic root nodules in legumes involves the induction and repression of numerous genes in conjunction with changes in the level of phytohormones. We have isolated several genes that exhibit differential expression patterns during the development of soybean nodules. One of such genes, which were repressed in mature nodules, was identified as a putative aldo/keto reductase and thus named Glycine max aldo/keto reductase 1 (GmAKR1). GmAKR1 appears to be a close relative of a yeast aldo/keto reductase YakC whose in vivo substrate has not been identified yet. The expression of GmAKR1 in soybean showed a root-specific expression pattern and inducibility by a synthetic auxin analogue 2,4-D, which appeared to be corroborated by presence of the root-specific element and the stress-response element in the promoter region. In addition, constitutive overexpression of GmAKR1 in transgenic soybean hairy roots inhibited nodule development, which suggests that it plays a negative role in the regulation of nodule development. One of the Arabidopsis orthologues of GmAKR1 is the ARF-GAP domain 2 protein, which is a potential negative regulator of vesicle trafficking; therefore GmAKR1 may have a similar function in the roots and nodules of legume plants.

• KSBB Journal
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• v.30 no.1
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• pp.11-20
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• 2015

Radiation causes various pathophysiological alterations in living animals, and it causes death at high doses by multiple mechanisms, including direct DNA damage and indirect oxidative stress. The search for useful radioprotectors has been an important issue in the field of radiation biology. Ideal radioprotectors should have low toxicity and an extended window of protection. As many synthetic compounds have toxic side effects, the natural products have attracted scientific attention as radioprotectors. Natural products that have been recently shown to be effective with various biological activities were found to have radioprotective effect. The aim of this review is to summary the recent research of the radioprotective effects of natural foods, especially focused on the glycobiological properties of mushrooms.

• Journal of Applied Biological Chemistry
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• v.57 no.2
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• pp.165-170
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• 2014

The stems of Viburnum erosum were extracted with 80% MeOH. The concentrated extract was partitioned with EtOAc, n-BuOH, and $H_2O$. From the EtOAc and n-BuOH fractions, four compounds were isolated through the repeated $SiO_2$, octadecyl silica gel, and Sephadex LH-20 column chromatographies. Based on NMR, MS, and IR spectroscopic data, the chemical structures were determined as betulinic aldehyde (1), koaburside (2), (6R,7E,9R)-9-hydroxymegastigma-4,7-dien-3-one-9-O-${\beta}$-D-glucopyranoside (3), and byzantionoside B (4). All the compounds were isolated for the first time from the stems of Viburnum erosum.