• Journal of Aquaculture
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• v.9 no.1
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• pp.43-55
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• 1996

The experiment was performed to evaluate the possibility of utilizing underground sea water for the seed production of tiger puffer, Takifugu rubripes. For this purpose, the effects of 6 different salinities (3.5, 7.0, 14.0, 20.0, 27.0, $33.0\%_{\circ}$) were determined based on the hatching rate of fertilized eggs, survival rate and the amount of food consumed by hatched larvae, where as the effects of 3 different salinities (20.0, 27.0, $33.0\%_{\circ}$) were also examined with rearing tiger puffer juvenile ($4.29{\pm}0.50$ cm in total length) for 50 days in the closed recirculating water system. As a results, either the hatching or the survival rate of more than $70.0\%$ were obtained from the fertilized eggs reared at the salinity of 27.0 to $33.0\%_{\circ}$, the early hatched larvae at 27.0 to $33.0\%_{\circ}$, and the 10-day-old larvae at 20 to $33.0\%_{\circ}$. At three different salinities, the survival rate of 20-day- and 30-day-old larvae turned out to be $89.0\%$ and $92.5\%$, respectively. The salinity for maximum food intake thus appeared to be from 27.0 to $33.0\%_{\circ}$. In this condition, 20-day-old hatched larvae consumed $323\~342$ Artemia nauplii and 30-day-old hatched larvae ate $1,559\~1,5791$ A. nauplii. The highest growth rate of fingerlings were observed at the salinity $27\%$ and followed by 33.0 and $20.0\%_{\circ}$, respectively. The relationship between the days of rearing (X) and the total length (Y) of the fingerlings were as follows : $33.0\%_{\circ}$ group : Y=0.107X-2.532 (r=0.982) $27.0\%_{\circ}$ group : Y=0.116X-3.195 (r=0.975) $20.0\%_{\circ}$ group : Y=0.116X-2.693 (r=0.987) The slopes of regression line estimated from $27.0\%_{\circ}$ and $33.0\%_{\circ}$ groups were significantly different from that of $20.0\%_{\circ}$ group.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.2
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• pp.224-230
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• 2014

Marine algae have long been recognized as a health and beauty food, based on its anti-tumor, anti-inflammatory and anti-obesity activities. In this study, methanol extracts were prepared from 10 different phaeophyta, after which DPPH radical scavenging and cytoprotective activities of HT-22 cells against ${\beta}$-amyloid protein ($A{\beta}$), which has neurotoxic effects, were investigated. In DPPH experiments, Ecklonia cava and Ishige okamurai showed strong ROS scavenging activities, whereas eight other phaeophyta including Petalonia binghamiae (P. bin) showed weak ROS scavenging activities. To validate the cytoprotective effects of 10 different phaeophyta in $A{\beta}$-induced HT-22 cells, protein expression levels of APP, BACE1, iNOS, phosphorylated ERK1/2, phosphorylated p38 and phosphorylated JNK1/2 were determined along with MTT assay. In the MTT assay, P. bin showed the best effective cytoprotective activity at a concentrations of $25{\mu}g/mL$, whereas Sargassum confusum, Colpomenia sinuosa, Myelophycus simplex, and Sargassum hemiphyllum showed potential. Determination of protein expression levels related to $A{\beta}$-induced neurotoxicity in the five selected phaeophyta showed that P. bin inhibited BACE1 and iNOS expression in $A{\beta}$-induced HT-22 cells. These results indicate that the cytoprotective effects of P. bin are mediated by suppressing the pathways involving $A{\beta}$-induced ERK and p38 activation.

• Journal of Aquaculture
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• v.13 no.2
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• pp.169-174
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• 2000

Reproductive cycle of U. unicinctus was studied from September 1998 to August 1999, using gonadosomatic index (CSI) as an indicator. In November, the CSI values were maximum for male (6.2) and female (7.0), respectively; the values were lowest for them (1.0 and 0.5) during the successive february. Subsequently, they rapidly increased and attained peak by March-April. The values decreased again in both sexes and remained unchanged until August. The index increased in October to attain the peak by November. The CSI values clearly indicated that there are two spawning events in a year, namely the first one during April-May and the second one in December. Reproductive cycle was classified into the following successive stages: in female, multipication (January~February, June ~Setember), maturation (March~April, November), spent (May and December), degeneration and resting (June and January), and in male, multiplication January ~ february, June ~September), maturation (March~April, October~November), spent (May and December) and degeneration and resting (January and June). Histological observations revealed that oocytes in the ovary matured simultaneously in November and March. At the same time, the envelopes of matured testis became thinner than those in the early stage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.9
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• pp.1139-1145
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• 2006

In this study, antioxidant activities of enzymatic and methanolic extracts from E. cava stem and leave were evaluated by measuring the scavenging activities on 1,1 diphenyl 2 picrylhydrazyl (DPPH), hydroxyl radical, hydrogen peroxide and the inhibitory effects on DNA damage induced by oxidative stress of cells. Enzymatic extracts were prepared by enzymatic hydrolysis of both stem and leave using food grade five different carbohydrases (Viscozyme, Celluclast, AMG, Termamyl, Ultraflo) and five proteases (Protamex, Kojizyme, Neutrase, Flavourzyme, Alcalase). The enzymatic extracts were lower than methanolic extracts in polyphenol contents, but higher in extraction yield by approximately 30%. The enzymatic extracts were superior to methanolic extracts in DPPH and H2O2 scavenging activities and DNA damage protective effect. There were no significant antioxidant activity difference between stem and leave, but the extracts of leave were relatively better than those of stem. In this study it is suggested that E. cava stem as well as its leave would be a good raw materials for antioxidants compound extraction and enzymatic hydrolysis would be a good strategy to prepare antioxidant extracts from seaweeds.

• Korean Journal of Environmental Biology
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• v.36 no.3
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• pp.359-369
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• 2018

Harmful algal blooms (HABs) are a serious problem for public health and fisheries industries, thus there exists a need to investigate the possible ways for effective control of HABs. In the present study, we investigated the algicidal effects of a newly developed GreenTD against the HABs (Chattonella marina, Heterosigma akashiwo, Cochlodinium polykriokides, and Heterocapsa circularisquama) and non-HABs (Chaetoceros simplex, Skeletonema sp. and Tetraselmis sp.), which is focused on the different population density and concentration gradients of algicidal substances. The time series viability of target alga was assessed based on the activity of Chl. a photosynthetic efficiency in terms of $F_v/F_m$, and in vivo fluorescence (FSU). Effective control of Raphidophyta, C. marina and H. akashiwo was achieved at a GreenTD concentration of $0.5{\mu}gL^{-1}$ and $0.2{\mu}gL^{-1}$, respectively, and regrowth of both the species was not observed even after 14 days. The inhibitory ratio of the dinoflagellate, C. polykriokides was more than 80% at $0.2{\mu}gL^{-1}$ of GreenTD. H. circularisquama was constantly affected in the presence of $0.2{\mu}gL^{-1}$ of GreenTD in the high- and low-population density experimental groups. On the other hand, diatoms, C. simplex, and Skeletonema sp. were not significantly affected even in the presence of $0.2{\mu}gL^{-1}$ of GreenTD and exhibited re-growth activity with the passage of incubation time. In particular, green alga Tetraselmis sp. remained unaffected even in the presence of the highest concentration of GreenTD ($1.0{\mu}gL^{-1}$), implying that non-HABs were not greatly influenced by the algicidal substances. As a result, the algicidal activity of GreenTD on the harmful and nonharmful algae was as follows: raphidophyte>dinoflagellates>diatoms>green alga. Consequently, our results indicate that inoculation of GreenTD substances into natural blooms at a threshold concentration ($0.2{\mu}gL^{-1}$) can maximize the algicidal activity against HABs species. If we consider the dilution and diffusion rate in the field application, it is hypothesized that GreenTD will demonstrate economic efficiency, thus leading to effective control against the target HABs in the closed bay.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.328-336
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• 2007

A piston core (587 cm long) was recovered from the upper slope of a seamount in the Korea Plateau. Three episodes of sedimentation were identified based on sedimentary facies, grain size distribution, carbonate constituents and initial $^{87}Sr/^{86}Sr$ ratio of carbonates. The lower part of the core, Unit I-a (core depth $465{\sim}587cm$) is composed of shallow marine carbonate sediments the deposited by storm surges, and is about $13{\sim}15Ma$ (Middle Miocene) based on $^{87}Sr/^{86}Sr$ initial ratio. This suggests that the depositional environment was relatively shallow enough to be influenced by storm activities. Unit I-b (core depth $431{\sim}465cm$) is mostly composed of turbidites, and Sr isotope ages of bivalves and planktonic formaminifera are about $11{\sim}14\;and\;6{\sim}13Ma$, respectively. This indicates that the Korea Plateau maintained shallow water condition until 11 Ma, and began to subside since then. However, planktonic foraminifera were deposited after 11 Ma and redeposited as turbidites as a mixture of planktonic foraminifera and older shallow marine carbonates about 6 Ma ago. Unit II (core depth $0{\sim}431cm$) is composed of pelagic sediments, and the Sr isotope age is younger than 1 Ma, thus the time gap is about 5 Ma at the unconformity. About 1 Ma ago, the Korea Plateau subsided down to a water depth of about 600 m. The sampling locality was intermittently influenced by debris flows and/or turbidity currents along the slope, resulting the deposition of re-transported coarse shallow marine and volcaniclastic sediments.