• The Korean Journal of Malacology
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• v.29 no.1
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• pp.15-21
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• 2013

Nitric oxide (NO) is an important intra-intercellular signaling molecule that regulates many physiological processes and participates in the development some pathological conditions in animals. In this study, we compared different methods for determining NO concentration in the hemocytes of Manila clam Ruditapes philippinarum. For measuring the intracellular NO levels, we used the specific fluorescent probe 4,5-diaminofluorescein diacetate (DAF-2 DA), and the quantification methods that were compared were based on image analysis, spectrophotometry, and flow cytometry. NO concentration could be determined using all the 3 methods, and the concentration varied significantly depending upon the presence of NO regulators in the hemocytes; NO concentration increased in the presence of L-arginine, while it decreased in the presence of N-nitro-L-arginine methyl ester. In particular, it is found that estimation of NO using a flowcytometry is more economical, reliable and accurate compared to image analysis and spectrophotometry. Accordingly we believe that determining NO concentration by using flowcytometry will be useful in evaluating physiological and pathological conditions in marine bivalves.

• Korean Journal of Ichthyology
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• v.30 no.4
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• pp.224-231
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• 2018

Dietary niches can support the coexistence of sympatric species in marine ecosystems, which can lead to the presence of greater abundances of those species. Stomach contents of silver croaker (Pennahia argentata) and Japanese sillago (Sillago japonica) inhabiting the Nakdong River estuary, Korea were analyzed to determine diet compositions and the presence of any size-related and inter-specific feeding relationships. These species were bottom-feeding predators that consumed mainly benthic crustaceans and mollusks, but polychaetes were also important in the S. japonica diets. Non-metric multidimensional scaling (nMDS) ordination and multivariate analyses based on weight contributions of the different prey taxa to stomach contents revealed significant inter-specific dietary differences. Size-related change was also significant for P. argentata diets, but not for S. japonica. Canonical analysis of principal coordinate (CAP) ordination plot further demonstrated that differences in the type and range of prey ingested by the two species contributed such an inter-specific difference in the diet compositions. The results from this study provide clear evidence of niche segregation between co-occurring P. argentata and S. japonica in the Nakdong River estuary, which would reduce the likelihood of inter-specific competition for food resources.

• Journal of Life Science
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• v.28 no.6
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• pp.639-647
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• 2018

A new heat shock protein 70 was identified in red-spotted grouper (Epinephelus akaara) based on an expression analysis. The cDNA of red-spotted grouper Hsp70 (designated RgHsp70) was cloned by the rapid amplification of cDNA ends (RACE) techniques. The full-length of RgHsp70 cDNA was 2,152 bp, consisting of a 5'-terminal untranslated region (UTR) of 105 bp, a 3'-terminal UTR of 274 bp, and an open reading frame (ORF) of 1,773 bp that encode a polypeptide of 590 amino acids with a theoretical molecular weight of 64.9 kDa and an estimated isoelectric point of 5.2. Multiple alignment and phylogenetic analyses revealed that the RgHsp70 gene shares a high similarity with other Hsp70 fish genes. RgHsp70 contained all three classical Hsp70 family signatures. The results indicated the RgHsp70 is a member of the heat shock protein 70 family. RgHsp70 mRNA was predominately expressed in the liver, with reduced expression noted in the head-kidney tissues. The expression analysis of different water temperatures (21, 18, 15 and $12^{\circ}C$) for sampled livers revealed that expression gradually increased at $12^{\circ}C$ compared to $21^{\circ}C$. In this study, the effects of water temperature lowering on the physiological conditions were investigated, and the results revealed that novel RgHsp70 may be an important molecule involved in stress responses.

• Journal of Aquaculture
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• v.16 no.2
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• pp.104-109
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• 2003

The present study aims to evaluate protein and phosphorus availabilities of five different dietary protein sources during the 6-week feeding trial in juvenile olive flounder, Paralichthys olivaceus as determined by growth performance and phosphorus retention. Five diets containing blood meal (BM), poultry by-product (PBP), squid liver powder (SLP), feather meal (FM) and soybean meal (SM) were prepared by mixing a basal diet (BD) with one of five test ingredients at the ratio of 7 to 3. As a reference diet, BD contains three different protein sources such as white fish meal, casein and gelatin. After 2 weeks of the conditioning period, fish initially averaging 2.7$\pm$0.02g (mean$\pm$SD) were randomly distributed into each aquarium as a group of 30 fish reared in the recirculating system. Fish of triplicate groups were fed one of six experimental diets (BD+five test diet). After 6-week feeding trial, pro- tein efficency ratio (PER) of fish fed BM diet was the lowest in experiment groups. While fish fed PBP diet showed a significant higher PER as compared to the FM diet, and fish fed SLP diet and BD were a higher PER than did fish fed PBP diet. However, there was no significant difference in PER among fish fed SLP diet, BD and SM diet, and between SM diet and PBP diet. Phosphorus retention efficiency of bone (PR $E_{b}$) of fish fed BM diet was the lowest in all the diets, and fish fed FM diet showed a higher PE $R_{b}$ than fish fed BD and SM diet. However, there was no significant difference in PER among fish fed FM diet, SLP diet and PBP diet, and among SLP diet, PBP diet, SM diet and BD. These results indicate that SLP could be a suitable protein source for low pollution diets of olive flounder in the future fish feeds market. Furthermore, PBP and SM are available protein source to reduce P waste in the oliver flounder aquaculture with the use of proper mixture of other protein sources and more processing to improve protein availibility of these.ese.

• 한국해양학회지
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• v.23 no.2
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• pp.76-88
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• 1988

Size distribution of suspended particulate materials (SPM) in the coastal waters of eastern Korea was studied using a laser particle size analyzer. Mean particle size (MPS) ranges from 3.69 to 8.40 ${\mu}m$ in surface waters, from 3.38 to 6.43 ${\mu}m$ in mid-depth waters, and from 3.88 to 8.30 ${\mu}m$ in near-bottom waters. For smaller MPS, the size distribution is unimodal, whereas it becomes polymodal as the MPS increases. Particle concentrations increased with the increases in MPS, suggesting that processes of adding larger particles in the waters such as resuspension of bottom sediments are more important in controlling MPS in the area than processes of removing smaller particles such as flocculation of fine particles. Observations of higher MPS near the coast in mid-depth waters, and at the continental slope in near-bottom waters appear to support the above idea. For surface waters with high MPS, mean particle density was noticably low, indicating the importance of biological activities in the formation of suspended particles.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.112-123
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• 1998

The objectives of this study are to investigate the trace elemental and stable isotopic compositions of aragonitic mollusk shells, such as Gomphina veneriformis melanaegis, Mytilidae and Umbonium coastatum, from the eastern coast of Korean peninsula and Cheju Island, and to compare their variations with latitude, that is, the temperature of the ambient seawater at which the skeletons grew. The Mg compositions of Gomphina veneriformis melanaegis tend to decrease with increasing water temperature, whereas those of Mytilidae and Umbonium coastatum do not show any trend. Sr compositions of Mytilidae tend to increase with increasing water temperature, whereas those of Gomphina veneriformis melanaegis decrease. Fe compositions of Umbonium coastatum tend to decrease with increasing water temperature, whereas those of Gomphina veneriformis melanaegis increase. Fe compositions of Mytilidae do not show any trend with water-temperature variations. Ba compositions of all the skeletons do not show any trend with water-temperature variations. Cd compositions of Mytilidae and Umbonium coastatum do not show any trend with increasing water temperature, whereas those of Gomphina veneriformis melanaegis increase. Cu compositions of Gomphina veneriformis melanaegis increase with increasing water temperature, whereas Mytilidae and Umbonium coastatum do not show any trend. Pb compositions of Umbonium coastatum do not show any tend with increasing water temperature, but those of other skeletons increase. Zn compositions of Mytilidae tend to decrease with increasing water temperature, whereas those of Gomphina veneriformis melanaegis increase. Zn compositions of Umbonium coastatum do not show any trend with increasing water temperature. Estimated water temperatures from oxygen isotopic data of all the skeletons are higher than the range of water temperature of the shallow seawater of the East Sea and around Cheju Island. The oxygen isotopic compositions of all the skeletons are well clustered, but they do not show any trend with latitude. Therefore, this could reflect that the organisms may not have secreted their shells in oxygen isotopic equilibrium with ambient seawater due to vital effect. Thus, isotopic compositions of all the organisms in this study may not be suitable for paleotemperature estimate.

• Korean Journal of Ichthyology
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• v.26 no.3
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• pp.171-178
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• 2014

Myogenesis is the formation process of multinucleated myofiber with a contractile capacity from muscle satellite cell (MSCs) during life. This process is tightly controlled by several transcription factors such as Pax3 and Pax7 (paired box protein 3 and 7), MEF2C (myocyte enhancer factor 2) and MRFs (myogenic regulatory factors) etc. On the contrary, myostatin (MSTN) is a transforming growth factor-${\beta}$ superfamily, which functions as a negative regulator of skeletal muscle development and growth. Carnosic acid (CA) is a major phenolic component in rosemary (Rosmarinus officinalis) and have been reported various biological activities such as anticancer, antioxidant, antimicrobial and therapeutic agents for amnesia, dementia, alzheimer's disease. This study was confirmed to effects of CA on muscle cell line and muscle tissue alteration of zebrafish by intramuscular injection or feeding methods. $10{\mu}M$ CA showed a non-cytotoxic on myoblast and a complete inhibition effect against myostatin activity on luciferase assay. In intramuscular injection experiment, the total protein and triglyceride amount of $10{\mu}M/kg$ of CA injected group increased by 11% and decreased by 13% compared to these of the no injected group. In histology analysis of muscle tissues by hematoxylin/eosin staining, the number of muscle fiber of $10{\mu}M/kg$ of CA injected group decreased by 29% and fiber area increased 40% compared to these of no injected group. In feeding experiment, the total protein and triglyceride amount no significance difference compared to these of the normal feeding group. In histology analysis, the number of muscle fiber of 1% CA fed group decreased by 35% and fiber area increased 56% compared to these of normal fed group. We identified that CA have an effect on hypertrophy of muscle fiber in adult zebrafish and the results of this study are considered as the basic data that can reveal the mechanisms of muscle formation via gene and protein level analysis.

• Geophysics and Geophysical Exploration
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• v.13 no.4
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• pp.323-329
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• 2010

Three deconvolution methods were applied to stacked seismic data obtained to investigate gas-hydrates in the Ulleung Basin, East Sea: (1) minimum-phase spiking deconvolution, (2) minimum-phase spiking deconvolution using an averaged wavelet from all traces, and (3) deterministic deconvolution using a wavelet with phases computed from well-logs. We analyzed the resolving property of these methods for lithological boundaries. The first deconvolution method increases temporal resolution but decreases lateral continuity. The second method shows, in an overall sense, similar results to the spiking deconvolution using a minimum phase wavelet for each trace; however, it results in a more consistent and continuous bottom-simulating reflector (BSR) and better resolved sub-BSR reflectors. The results from the third method reveal more detailed internal structures of debris-flow deposits and increased continuity of reflectors; in addition, the seafloor reflection and the BSR appear to have changed to a zero-phase waveform. These properties help more precisely estimate the distribution and reserves of gas hydrates in the exploration area by improving analysis of facies and amplitude of the BSR.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.124-141
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• 1998

The objectives of this study are to investigate the trace (minor) elemental and isotopic compositions of calcitic skeletons, such as barnacle, echinoid, branching and encrusting calcareous algae and oyster, from the eastern coast of Korean peninsula and Cheju Island, and to compare their variations with latitude, that is, the temperature of ambient seawater at which the skeletons grew. Articulated and encrusting red algae are composed of high-Mg calcite (7-21 mol% $MgCO_3$). Echinoids are also composed of high-Mg calcite (7-15 mol% $MgCO_3$). Whereas barnacles are composed of low-Mg calcite (1-5 mol% $MgCO_3$). The Mg compositions of articulated red algae, barnacle and oyster tend to increase with increasing water temperature, whereas those of encrusting red algae and echinoid do not show any trend. Sr compositions of articulated red algae, echinoid and barnacle tend to decrease with increasing water temperature, whereas those of encrusting red algae and oyster do not show any trend. Mn compositions of articulated red algae and encrusting red algae decrease with an increase of water temperature, whereas those of echinoid and barnacle do not show any trend. Fe compositions of articulated red algae tend to decrease with increasing water temperature, whereas those of encrusting red algae and oyster increase. Fe compositions of echinoid and barnacle do not show any trend with water temperature variations. Ba compositions of echinoid and low-magnesium calcitic skeletons do not show any trend with water temperature variations. Ba compositions of articulated red algae tend to decrease with increasing water temperature, whereas those of encrusting red algae increase. Cd and Pb compositions of all the skeletons tend to increase with increasing water temperature. Cu compositions of encrusting red algae increase with increasing water temperature, whereas articulated red algae, echinoid, barnacle and oyster do not show any trend. Zn compositions of high-magnesium calcitic skeletons and low-magnesium calcitic skeletons do not show any trend. Estimated water temperatures from oxygen isotopic data of all the skeletons except for the barnacle arc higher than the range of temperature of the shallow seawater of the East Sea and around Cheju Island. The oxygen isotopic compositions of oyster and echinoid are well clustered, and they do not show any trend with increasing water temperature. Therefore, this could reflect that the organisms have not secreted their shells in oxygen isotopic equilibrium with ambient seawater due to vital effect. Thus, the oxygen isotopic composition of barnacle can potentially be utilized for paleotemperature estimate whereas those of other organisms in this study may not be useful.

• Journal of Aquaculture
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• v.19 no.4
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• pp.288-298
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• 2006

Larval distribution of bivalve from 29 stations in Deukryang Bay was examined from May to November in 1995. The abundance of total larvae increased from May ($3,736\;inds/m^3$) and reached maximum in August ($174,616\;inds/m^3$). But it decreased continuously until November ($2,171\;inds/m^3$). D-shape, early umbone and advanced umbone stage larvae composed of 76%, 18% and 6%, respectively, of total bivalve larvae. Nine larval species of bivalve were identified in this study. The mean abundance of Scapharca subcrenata larvae was $14,030\;inds/m^3$, which was 33.5% of total identified larvae. S. broughtonii (16.2%), Crassostrea gigas (12.5%), Mytilus edulis (10.2%) were also major species in order of their abundance. Considering the monthly larval occurrence in Deukryang Bay, main spawning month of bivalves except M. edulis and M. senhausia was estimated as July. Even though the spatial distribution of bivalve larvae in Deukryang Bay was different by the species, the larvae were generally abundant in the inner and west area of the bay, where was shallower and higher water temperature than the entrance and east area of the bay.