• The Korean Journal of Malacology
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• v.7 no.1
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• pp.76-86
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• 1991

A scanning electron microscopic stuey on the glochidial encystment study on the golchidal encystment and excystment of Anodonta fukudai on Acheilognathus yamatsutae, a common natural hostfish, was conducted. The glochidium easily attached to the unscaled surfaces of the host fish such as the fins, lips, and the wall of the buccal cavity. For this study, the fins infected with the glochidia wer mainly observed in a series. The process of encystment was slowly progressed, for 21-25 hours for the early cyst and for 2-4 days for the thick walled cyst. The process of excystmint was visually detected on the 12th day since the attachmint was occurred. The first visible sign was a little tear of the cyst wall covering the hinge and marginal zones of the juvenile clam and once the little sign was appeared the progress of emerging and dettachmint of the juvenile clam from the host was finished relatively in short time. During the process of the encystmint, the cells participationg in covering the attached glochidirm were seened mainly supplied by migration from the surroundings. the shapes of the cells migrating and covering the glochidium were considerably changed and the surface structures of the cells lost their normal pattern of the surface ridges. The unstable forms of the cells were observed almost all throughout the period of the glochidial attachment. No cells of the host epithelium, which were still attached to the juvenile clam energing from the cyst, were observed. The most juvenile clams escaped from the cysts were a little bigger than the glochidia and they were still possessed of the golchidial hooks even though much degenerated. The first growth line was appeared on the shell valves of the juvenild clam when observed right after dettachment.

• Ocean and Polar Research
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• v.25 no.4
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• pp.653-662
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• 2003

Changes in the area of geo-ecosystem $(62^{\circ}09'S,\;58^{\circ}31'w)$ reflect climatic changes in the South Shetland Islands. Air temperature and deglaciation will increase. The ice-free space area at the SSSS 8- (ASPA 121) site has enlarged threefold during the last 21 years, thus creating conditions for inhabitation and succession. Wind, water and snow play important roles in transportation of geochemical components. They distribute nutrients, mineral substances, seeds, fragments of plants and animals, etc. Plant and animal colonization is patchy and it happens at random in an 'island' - like manner. The colonization pattern is dependant, to a high degree on physical factors. The newly uncovered ice-free areas are at first inhabited by a vascular plant known as the Deschampsia antarctica. The border of the land-oasis with Admiralty Bay is the place where the processes related to animal feeding at the sea and reproduction on the land take place. Bird colonies and pinniped lairs form centers of fertilization surrounded by high chemical gradients dependent on the direction of the flow of nutrients $(e.g.\;NH_4)$. During the last 25 years, the numbers of penguins in this region have decreased, and thus the amount of materials excreted on land has diminished. The numbers of fur seals change in multi-annual cycles, and their migration into this area is related to the E1 $Ni\~{n}o$ phenomenon. The numbers of elephant seals in the area did not change. Organic matter deposited by the sea onto the shore are a source of nutrients and deficient chemical elements on land. Mineral matter is washed out into the waters of Admiralty Bay. These processes change seasonally, and multi annually. Negative effects on the environment at Arctowski Station induced by man are slight, but noticeable nevertheless. Physical processes have the largest influence on the living conditions and distribution of plants and animals, and as a consequence, on the functioning of the geo-ecosystem in the coastal-shore zone of the Maritime Antarctic.

• Journal of Korea Water Resources Association
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• v.48 no.11
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• pp.879-889
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• 2015

The pattern of headward erosion at tributary and the separation zone formation in a loosed bed at confluence according to the confluence angle, discharge ratio, and dredging depth ratio have been analyzed. The separation zone is defined the inside of zero velocity boundary at downstream of confluence. The limit of separation zone occurrence is presented with dredging depth ratio. The propagation length of knickpoint increases as the confluence angle, discharge ratio, and dredging depth ratio increase in general and its regression equation has been suggested. The length and width ratios of separation zone in a loosed bed increase as discharge ratio and confluence angle increase as well as in a fixed bed. The length ratio decreases and the width ratio increases as dredging depth ratio increases results in great increase of shape factor and backwater rise by the conveyance reduction at confluence. The regression equation of shape factor with confluence angle, discharge ratio, and dredging depth ratio has been suggested.

• The Journal of Korean Society of Virology
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• v.29 no.2
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• pp.75-86
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• 1999

Rotaviruses belong to Reoviridae causes diarrhea in human beings as well as domestic animals. This study was conducted to see what type of human rotaviruses are distributed in Seoul and Kyung-gi province. Twenty two of 81 patients showed rotavirus positive with diagnostic kit and RNA electropherosis. We isolated all of rotaviruses from the patients. Electropherotypes of 22 isolates showed 4:2:3:2 pattern whereas those migration patterns were long type. All of those isolates belonged to group A. Twenty out of 22 isolates reacted with monoclonal antibodies specific to G1, P1A and subgroup II, whereas rest of them, A-29 and K-30 reacted with subgroup I specific monoclonal antibody. The nucleotide sequence of an isolate K-21 showed $98{\sim}100%$ and $90{\sim}96%$ homologies with those of Wa and KU strain, respectively.

• Molecules and Cells
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• v.40 no.10
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• pp.761-772
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• 2017

Glioblastoma is the most frequent and most aggressive brain tumor in adults. Solute carrier family 8 member 2 (SLC8A2) is only expressed in normal brain, but not present in other human normal tissues or in gliomas. Therefore, we hypothesized that SLC8A2 might be a glioma tumor suppressor gene and detected the role of SLC8A2 in glioblastoma and explored the underlying molecular mechanism. The glioblastoma U87MG cells stably transfected with the lentivirus plasmid containg SLC8A2 (U87MG-SLC8A2) and negative control (U87MG-NC) were constructed. In the present study, we found that the tumorigenicity of U87MG in nude mice was totally inhibited by SLC8A2. Overexpression of SLC8A2 had no effect on cell proliferation or cell cycle, but impaired the invasion and migration of U87MG cells, most likely through inactivating the extracellular signal-related kinases (ERK)1/2 signaling pathway, inhibiting the nuclear translocation and DNA binding activity of nuclear factor kappa B ($NF-{\kappa}B$), reducing the level of matrix metalloproteinases (MMPs) and urokinase-type plasminogen activator (uPA)-its receptor (uPAR) system (ERK1/2-$NF-{\kappa}B$-MMPs/uPA-uPAR), and altering the protein levels of epithelial to mesenchymal transitions (EMT)-associated proteins E-cardherin, vimentin and Snail. In addition, SLC8A2 inhibited the angiogenesis of U87MG cells, probably through combined inhibition of endothelium-dependent and endothelium-nondependent angiogenesis (vascular mimicry pattern). Totally, SLC8A2 serves as a tumor suppressor gene and inhibits invasion, angiogenesis and growth of glioblastoma.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.2
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• pp.124-137
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• 2010

This study was started with the objective of restoring abandoned embanked farms, which are recently increasing, to mud flat by putting in least amount of energy in the aspect of environmental restoration. For the direction and establishment of the proposal for the restoration of mud flat using embanked farms, a case of Maipo Wetland in Hongkong was analyzed, and a proposal was prepared considering the condition of mud flat in Gochang. The restoration of mud flat in Gochang is intended to create various wetland ecological spaces as well as to provide opportunities for experience, education, recreation, and tourism. Effort was made to development an environment closest to the local ecological environment considering the shape and topographical condition of existing abandoned farms. For construction of the habitat, a target species was chosen and the plan for selection, planting, and management of species of trees suitable for the target species was established. In addition, the water level will be controlled by water gates to conform to the resting, spawning, breeding, and migration period considering the behavioral pattern of waders, the target species. The research on the restoration of mud flat in Korea is in incipient stage and this study provided an opportunity to review the possibility of restoration of abandoned embanked farms to mud flat. For the success of mud flat restoration from a long-term perspective, development of acclimating design infrastructure, technology improvement for mud flat restoration, and basis of partnership for the maintenance should be prepared in a systematical way.

• Molecules and Cells
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• v.22 no.2
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• pp.146-153
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• 2006

Cell polarity is critical for the division, differentiation, migration, and signaling of eukaryotic cells. RAX2 of budding yeast encodes a membrane protein localized at the cell cortex that helps maintain the polarity of the bipolar pattern. Here, we designate SPAC6f6.06c as $rax2^+$ of Schizosaccharomyces pombe, based on its sequence homology with RAX2, and examine its function in cell polarity. S. pombe $rax2^+$ is not essential, but ${\Delta}rax2$ cells are slightly smaller and grow slower than wild type cells. During vegetative growth or arrest at G1 by mutation of cdc10, deletion of $rax2^+$ increases the number of cells failing old end growth just after division. In addition, this failure of old end growth is dramatically increased in ${\Delta}tea1{\Delta}rax2$, pointing to genetic interaction of $rax2^+$ with $tea1^+$. ${\Delta}rax2$ cells contain normal actin and microtubule cytoskeletons, but lack actin cables, and the polarity factor for3p is not properly localized at the growing tip. In ${\Delta}rax2$ cells, and endogenous rax2p is localized at the cell cortex of growing cell tips in an actin- and microtubule-dependent manner. However, ${\Delta}rax2$ cells show no defects in cell polarity during shmoo formation and conjugation. Taken together, these observations suggest that rax2p controls the cell polarity of fission yeast during vegetative growth by regulating for3p localization.

• Journal of Magnetics
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• v.13 no.3
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• pp.110-113
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• 2008

In this study, heavy rare earth garnet $Tb_2Bi_1Ga_1Fe_4O_{12}$ powders were fabricated by a sol-gel and vacuum annealing process. The crystal structure was found to be single-phase garnet with a space group of Ia3d. The lattice constant $a_0$ was determined to be 12.465 ${\AA}$. From the analysis of the vibrating sample magnetometer (VSM) hysteresis loop at room temperature, the saturation magnetization and coercivity of the sample are 7.64 emu/g and 229 Oe, respectively. The N$\acute{e}$el temperature($T_N$) was determined to be 525 K. The M$\ddot{o}$ssbauer spectrum of $Tb_2Bi_1Ga_1Fe_4O_{12}$ at room temperature consists of 2 sets of 6 Lorentzians, which is the pattern of single-phase garnet. From the results of the M$\ddot{o}$ssbauer spectrum at room temperature, the absorption area ratios of Fe ions on 24d and 16a sites are 74.7% and 25.3%(approximately 3:1), respectively. These results show that all of the non-magnetic Ga atoms occupy the 16a site by a vacuum annealing process. Absorption area ratios of Fe ions are dependent not only on a sintering condition but also on the temperature of the sample. It can then be interpreted that the Ga ion distribution is dependent on the temperature of the sample. The M$\ddot{o}$ssbauer measurement was carried out in order to investigate the atomic migration in $Tb_2Bi_1Ga_1Fe_4O_{12}$.

• Korean Journal of Materials Research
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• v.17 no.9
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• pp.453-457
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• 2007

Interest in use of ink-jet printing for pattern-on-demand fabrication of metal interconnects without complicated and wasteful etching process has been on rapid increase. However, ink-jet printing is a wet process and needs an additional thermal treatment such as an annealing process. Since a metal ink is a suspension containing metal nanoparticles and organic capping molecules to prevent aggregation of them, the microstructure of an ink-jet printed metal interconnect 'as dried' can be characterized as a stack of loosely packed nanoparticles. Therefore, during being treated thermally, an inkjet-printed interconnect is likely to evolve a characteristic microstructure, different from that of the conventionally vacuum-deposited metal films. Microstructure characteristics can significantly affect the corresponding electrical and mechanical properties. The characteristics of change in microstructure and electrical resistivity of inkjet-printed silver (Ag) films when annealed isothermally at a temperature between 170 and $240^{\circ}C$ were analyzed. The change in electrical resistivity was described using the first-order exponential decay kinetics. The corresponding activation energy of 0.44 eV was explained in terms of a thermally-activated mechanism, i.e., migration of point defects such as vacancy-oxygen pairs, rather than microstructure evolution such as grain growth or change in porosity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.749-756
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• 2003

Hydroacoustic and open-closing zooplankton net survey were conducted to understand the characteristics of the sound scattering layer (SSL) and to estimate the density of an euphausiid (Euphausia pacifica) in the SSL, in the northwestern part of the East China Sea. The survey was carried out during July 6-9 2002 at 8 sampling stations for zooplankton. The virtual echogram technique was used to identify E. pacifica from all acoustic scatters. Mean volume backscattering strength difference $(MVBS_{120kHz-38kHz})$ and target strength equation for E. pacifica were derived from the Distorted-wave Born Approximation (DWBA) model. Although vertical migration of the SSL is similar to the general pattern, dispersion at night shows some differences. Estimated mean density using acoustic data ranged from $20.4-221.4\;mg/m^3$ over the whole depth, and $87.1-553.5\;mg/m^3$ in the SSL. The density using the zooplankton net ranged from $0.2-362.4\;mg/m^3$ and was not related to net deploying method. The results from the acoustic and net survey suggest that E. pacifica might be an important zooplankton community in the northwestern part of the East China Sea.