• Korean Journal Plant Pathology
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• v.3 no.4
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• pp.291-298
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• 1987

Samples showing mosaic symptom of cowpea (Vigna sesquipedalis) with vein banding, chlorotic spot, vein yellow were collected from Chinju areas in Korea, Two viruses were distinguishable by stability in sap, host range, and relations with cells and tissues were examined under an electron microscope, Blackeye cowpea mosaic(BICMV) was sap-transmissible to 7 plant species in 2 families, Of the plants, only leguminous species were systemically infected. This virus was inactivated by heating at $50-65^{\circ}C$ for 10 min, by diluting at $10^{-4}-10^{-5}$, and aging at room temperature for 1-6 days. Preparations examined under the electron microscope by direct negative staining method(DN -method) always showed particles of flexuous filament bout 750nm in length and cytopasmic inclusions. Cytoplasmic inclusions and virus particles were also confirmed to present in the cytoplasm of a mesophyll cell by ultrathin sections of BICMV infected cowpea leaves. Cucumber mosaic virus (CMV) was transmitted by sap- inoculation on inoculated leaves of Chenopodium amaranticolor, C. quinoa producing local lesions, but non-inoculated upper leaves of Nicotiana glutinosa, Cucurbita pepo and Vigna sesquipedalis producting systemic mosaic symptoms. Electron microscopic examination of virus preparation by direct negative staining showed spherical particles of about 30nm in diameter. In ultrathin sections of CMV infected tissues, virus particles of crystalline array were found in the vacuole and a large number of virus particles were found in the cytoplasm and the plasmodesmata of mesophyll cells.

• Journal of Life Science
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• v.19 no.10
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• pp.1478-1483
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• 2009

A solid-state culture based on grain materials was attempted to produce a fibrinolytic enzyme for blood circulation improvement using Bacillus subtilis BK-17. The spore, rather than vegetative cell inoculation, of B. subtilis BK-17 on the solid-state culture was effective in the production of a fibrinolytic enzyme. Maximum spore production was obtained with a SFM medium (0.8% nutrient broth, 0.05% yeast extract, $10^{-1}$ M $MgCl_2$, $10^{-3}$ M $FeCl_3$, $10^{-4}$ $MnCl_2$, $10^{-5}$ M dipicolic acid, pH 6.5). Optimal pH and temperature were pH 6 and $30^{\circ}C$, respectively. The spore production reached a maximum at 60 hours of incubation. Bacillus subtilis BK-17 on the mung bean solid-state culture produced greater fibrinolytic activity, and less activity was seen in other grains such as kidney bean, soybean and corn. Protein and lipid contents of fermented soybeans were about 10 - 30% more than those of unfermented soybeans. Amino acid content was also 5 - 20% more than that of unfermented soybeans. These results indicated that fermented solid-state culture medium, fermented soybean in this case, can be utilized as a food supplement.

• The Korean Journal of Food And Nutrition
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• v.19 no.4
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• pp.358-365
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• 2006

To study simultaneous water and solute transport kinetics during soaking in concentrated solution, the influence of the concentration and molecular weight of the solute(polyethylene glycol(PEG) and NaCl) in the soaking solution and the temperature on the water loss and solute gain rates were observed by using a model vegetable tissue(potato). When potato slices$(4cm{\times}4cm{\times}0.1cm)$ soaked in 60% PEG solutions, the water loss rate of the early phase decreased with increasing of the molecular weight of PEG from 200 to 6,000, while the final water loss increased with increasing the molecular weight of PEG and it reached to 80%. The cell wall of potato tissue was permeable to NaCl and PEGs of which average molecular weight is smaller than 400 but it was not permeable to PEG 600 and larger molecules. PEG which has average molecular weight below 600 induced plasmolysis and those above 600 induced cytorrhysis. The water loss rate of potato sample soaked in smaller molecular weight PEG solution was faster than those soaked in higher molecular weight PEG solution before cytorrhysis happened. The water loss rate was reversed after cytorrhysis happened. The volume change of potato within the first 60 minutes was larger in low molecular PEG solution but the final ratio of decreasing volume was larger in high molecular PEG solutions. In PEG 200 solution, the potato tissue was slightly shrinked without shape change. However, in PEG 4,000 solution, volume of potato was reduced significantly and potato tissue was twisted.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.689-693
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• 1993

${\alpha}-galactosidase$ releases galactoside from raffinose and stachyose which are the major sugars in soybean, Although raffinose and stachyose were known as flatulence factors, these sugars were recently claimed as bifidus factors. In this experiment we studied the properties of ${\alpha}-galactosidase$ and its production from Bifidobacterium sp. Int-57. Int-57 produced higher level of ${\alpha}-galactosidase$ than other intestinal bacteria. The production of ${\alpha}-galactosidase$ was greater when grown on raffinose compared with other carbohydrates tested. Partially purified ${\alpha}-galactosidase$ was obtained after sonication of harvested cell pellet followed by DEAE-cellulose chromatography and Sepharose CL-6B gel filtration, and assayed using PNP-${\alpha}-galactosidase$ as a substrate. Optimum pH for activity was 7.0 and optimum temperature was $40^{\circ}C$. At 5 mM concentration of metal ions, $CoCl_{2}\;and\;CuCl_{2}$ and inhibited the enzyme activity by 33% and 21% respectively. The enzyme was shown to hydrolyse genuine substrates, i.e. raffinose and stachyose.

• The Korean Journal of Malacology
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• v.15 no.2
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• pp.105-113
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• 1999

This study was measured environmental factors of flat oyster habitats and biomass of flat oyster to improve the productivity of flat oyster. Water temperature and salinity of the flat oyster habitat ranged from 5.5 to 27.4$^{\circ}C$ and from 31.2 to 33.4 , respectively. Average concentrations of DO, COD, DIN and PO$\_$4/$\^$3/ -P were 7.11 mg/l, 4.55 $\mu\textrm{g}$-at./l and 0.36 $\mu\textrm{g}$-at./l respectively. Surface sediments at the sampling area were composed of coarse sand, sandy silt and silty sand. Average level of IL, COD and AVS in the surface sediments were 2.6%, 13.70 mg/g dry and 0.33 mg/g dry respectively. In each sampling station, total standing crops of phytoplankton showed peaks twice in February and August. Dominant species of phytoplankton occurred in Haechang Bay throughout the year were Skeletonema costatum, Paralia sulcata, Eucampia zodiacus, Chaetoceros curvicetus, C. affinis, C. debilis, C. decipiens, Asterionella glacialis, Pseudonitzschia longissima, Pseudonitzschia seriata, Ceratium furca and C. fusus. Ten species of the bivalves were collected at the flat oyster habitat. Most of bivalves were the eutrophic species Ostrea denselamellosa, Crassostrea gigas, Ruditapes philippinarum, Scaphraca subcrenata, Scapharca broughtonii, Atrina pectinata, Fulvia mutica, Mytilus edulis, Protothaca jedoensis and Megacardita ferruginosa. The mean density of them was 21 inds./㎡ (479.14 g/㎡), while that of the flat oyster was at 0.25 inds./㎡ (231.25 g/㎡).

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.2
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• pp.164-167
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• 2004

This study was carried out to investigate in vitro fertilization and development of in vitro matured pig oocytes inseminated with the Duroc boar sperm by different sperm washing media after thawing of the 5 ml frozen straws. Immature follicular oocytes (30-40) were transferred into each well of a Nunc 4-well multidish containing $500{\mu}l$ mTCM199 maturation medium. The sperm rich portion of ejaculates was collected into a 250 ml insulated vacuum bottle and gradually cooled 22 to $24^{\circ}C$ over a 2 h period. Semen was centrifuged at 800 g for 10 min and the seminal plasma discarded. Sperm were esuspended in a lactose-egg yolk and N-acetyl-Dglucosamine (LEN) diluent to contain $1{\times}10^{9}$ sperm/ml and cooled to $5^{\circ}C$ over a 2 h period. Immediately before freezing, semen was rediluted with an equal volume of LEN+4% glycerol and packed into 5 ml straws. After thawing of the 5 ml straw, the 5 ml semen was diluted with 20 ml Beltsville thawing solution (BTS) at room temperature. Oocytes were inseminated with untreated (unwashed and nonpreincubated) or treated sperm (washed two times in BTS, mTLP-PVA and mTBM media, respectively and nonpreincubated) with $2{\times}10^{7}$ sperm concentration. Oocytes were coincubated for 6 h in $500{\mu}l$ mTBM fertilization. At 6 h after IVF, oocytes were transferred into $500{\mu}l$ NCSU-23 culture medium for further culture of 6 h. Sperm penetration, polyspermy and male pronuclear formation of oocytes at 12 h after IVF and developmental ability of oocytes at 48 h after IVF were evaluated. Sperm penetration rate, male pronuclear formation and rate of cleaved embryos were higher in the BTS, mTLP-PVA and mTBM treatments than the unwashed treatment (p<0.05). The rate of blastocysts from the cleaved oocytes (2-4 cell stage) were higher in the mTLP-PVA treatment than in the unwashed, BTS and mTBM treatments. In conclusion, we recommend the washing of frozen-thawed sperm with mTLP-PVA medium before in vitro fertilization of oocytes in mTBM medium.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4205-4209
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• 2011

The $Li_2Mn_{0.5}Fe_{0.5}SiO_4$ silicate was prepared by blending of $Li_2MnSiO_4$ and $Li_2FeSiO_4$ precursors with same molar ratio. The one of the silicates of $Li_2FeSiO_4$ is known as high capacitive up to ~330 mAh/g due to 2 mole electron exchange, and the other of $Li_2FeSiO_4$ has identical structure with $Li_2MnSiO_4$ and shows stable cycle with less capacity of ~170 mAh/g. The major drawback of silicate family is low electronic conductivity (3 orders of magnitude lower than $LiFePO_4$). To overcome this disadvantage, carbon composite of the silicate compound was prepared by sucrose mixing with silicate precursors and heat-treated in reducing atmosphere. The crystal structure and physical morphology of $Li_2Mn_{0.5}Fe_{0.5}SiO_4$ was investigated by X-ray diffraction, scanning electron microscopy, and high resolution transmission electron microscopy. The $Li_2Mn_{0.5}Fe_{0.5}SiO_4$/C nanocomposite has a maximum discharge capacity of 200 mAh/g, and 63% of its discharge capacity is retained after the tenth cycles. We have realized that more than 1 mole of electrons are exchanged in $Li_2Mn_{0.5}Fe_{0.5}SiO_4$. We have observed that $Li_2Mn_{0.5}Fe_{0.5}SiO_4$ is unstable structure upon first delithiation with structural collapse. High temperature cell performance result shows high capacity of discharge capacity (244 mAh/g) but it had poor capacity retention (50%) due to the accelerated structural degradation and related reaction.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.1
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• pp.11-18
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• 2020

High-pressure synchrotron X-ray powder diffraction experiments were performed on natural illite (K_0.65Al₂(Al_0.65Si_3.35)O₁₀(OH)₂) using diamond anvil cell (DAC) under two different pressure transmitting media (PTM), i.e., water and ME41 (methanol:ethanol = 4:1 by volume). When using water as PTM, occasional heating was applied up to about 250℃ while reaching pressure up to 2.7 GPa in order to promote both hydrostatic conditions and intercalation of water molecules into the layer. When using ME41, pressure was reached up to 6.9 GPa at room temperature. Under these conditions, illite did not show any expansion of interlayer distance or phase transitions. Pressure-volume data were used to derive bulk moduli (K₀) of 45(3) GPa under water and 51(3) GPa under ME41 PTM. indicating no difference in compressibility within the analytical error. Linear compressibilities were then calculated to be β^a = 0.0025, β^b = 0.0029, β^c = 0.0144 under ME41 PTM showing the c-axis is ca. six times more compressible than a- and b-axes. These elastic behaviors of illite were compared to muscovite, one of its structural analogues.

• Development and Reproduction
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• v.2 no.1
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• pp.101-109
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• 1998

Spermatogenesis and reproductive cycle of the razor clam, solen grandis, were investigated monthly by histological and cytological observations. Samples were collected from natural intertidal population at Oshik-do, Kunsan, Korea, for one year, beginning from January to December, 1993. solen grandis is dioecious. Morphological structures of the spermatozoon of this species ar esimilar to those of other bivalve spermatozoa having a primitive type; i.e., a small head, a cap-shaped acrosome and a short mid-piece with four mitochondria surrounding axial filament. The head of spermatozoon is approximately 2 \mu m in length and sperm tail is about 20 \mu m long. The axoneme of tail flagellum consists of nine pairs of peripheral microtubules at the periphery and a pair of central microtubules at the center. Four spherical mitochondria form the paranucleus. Spawning occures once a year between early June and July, and the main spawning was observed in July when seawater temperature reaches above 20 \circ C. The reproductive cycle of male razor clam can be divieded into fivesuccessive stages; early active (December to january), late active (January to march), mature (March to early August), partially spawned (June to July), and spent/inactive stage (August to December).

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.36-36
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• 2017

Out of twenty common protein amino acids, there are many kinds of non protein amino acids (NPAAs) that exist as secondary metabolites and exert ecological functions in plants. Mimosine (Mim), one of those NPAAs derived from L. leucocephala acts as an iron chelator and reversely block mammalian cell cycle at G1/S phases. Cysteine (Cys) is decisive for protein and glutathione that acts as an indispensable sulfur grantor for methionine and many other sulfur-containing secondary products. Cys biosynthesis includes consecutive two steps using two enzymes-serine acetyl transferase (SAT) and O-acetylserine (thiol)lyase (OASTL) and appeared in plant cytosol, chloroplast, and mitochondria. In the first step, the acetylation of the ${\beta}$-hydroxyl of L-serine by acetyl-CoA in the existence of SAT and finally, OASTL triggers ${\alpha}$, ${\beta}$-elimination of acetate from OAS and bind $H_2S$ to catalyze the synthesis of Cys. Mimosine synthase, one of the isozymes of the OASTLs, is able to synthesize Mim with 3-hydroxy-4-pyridone (3H4P) instead of $H_2S$ for Cys in the last step. Thus, the aim of this study was to clone and characterize the cytosolic (Cy) OASTL gene from L. leucocephala, express the recombinant OASTL in Escherichia coli, purify it, do enzyme kinetic analysis, perform docking dynamics simulation analysis between the receptor and the ligands and compare its performance between Cys and Mim synthesis. Cy-OASTL was obtained through both directional degenerate primers corresponding to conserved amino acid region among plant Cys synthase family and the purified protein was 34.3KDa. After cleaving the GST-tag, Cy-OASTL was observed to form mimosine with 3H4P and OAS. The optimum Cys and Mim reaction pH and temperature were 7.5 and $40^{\circ}C$, and 8.0 and $35^{\circ}C$ respectively. Michaelis constant (Km) values of OAS from Cys were higher than the OAS from Mim. Inter fragment interaction energy (IFIE) of substrate OAS-Cy-OASTL complex model showed that Lys, Thr81, Thr77 and Gln150 demonstrated higher attraction force for Cys but 3H4P-mimosine synthase-OAS intermediate complex showed that Gly230, Tyr227, Ala231, Gly228 and Gly232 might provide higher attraction energy for the Mim. It may be concluded that Cy-OASTL demonstrates a dual role in biosynthesis both Cys and Mim and extending the knowledge on the biochemical regulatory mechanism of mimosine and cysteine.