• Korean Journal of Microbiology
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• v.45 no.4
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• pp.368-376
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• 2009

A red pigment-producing bacterial strain was isolated from sediment sample of the East China Sea. The isolate was identified by analysis based on 16S rDNA sequence and morphological, physiological properties, biochemical characteristics and fatty acid composition. Phylogenetic analysis based on 16S rDNA sequence showed that isolate represent a phyletic lineage within the genus Zooshikella, and this strain was most closely related to Zooshikella ganghwensis KCTC $12044^T$ (AY130994) (99.79%). The strain was Gram-negative, aerobic and required NaCl at 0.5~8.0% for growth. The predominant cellular fatty acids were saturated and monounsaturated straight-chain fatty acids. Consequently, this strain was identified as a member of the genus Zooshikella and designated as Zooshikella sp. JE-34. The pigment showed characteristics similar to prodigiosin, a well-known red pigment previously detected in Serratia marcescens. The antimicrobial activity of Zooshikella sp. JE-34 bacterial pigment was tested against 18 microorganisms, which were fish and human pathogens. The Zooshikella sp. JE-34 red pigment showed high antimicrobial activity against Streptococcus iniae, S. parauberis, S. mutans, Staphylococcus aureus, and Propionibacterium acnes.

• Korean Journal of Environmental Agriculture
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• v.6 no.1
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• pp.50-60
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• 1987

Sensitivity, expressed in the $96h-LC_{50}$ determined with continuous flow system, was compared for eight developmental stages of Oryzias latipes with butachlor, diazinon and fenitrothion. Significance of the laboratory determined $96h-LC_{50}$ in real field situation was evaluated for butachlor using outdoor model agrosystem. In the laboratory tests, the most sensitive stage was post-larva stage IV(7 days after hatching) with $96h-LC_{50}$ of 0.14, 1.4, and 1.6ppm for butachlor, diazinon and fenitrothion, respectively, whereas the least sensitive stage was early embryo stage(1 day after fertilization), and then the susceptibility was somewhat stable after 21days after hatching. In the model agrosystem test, the highest concentration of 0.53ppm of butachlor in water was obtained at the 2nd day after application. The stages IV and VIII showed mortality of over 50% at 96 hours after application. It is concluded that the conventional use of butachlor in the field would cause significant adverse effect on O. latipes. It is suggested that sensitivity test at the early life stages with fish is an important part of the ecotoxicological assessment of chemicals.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.660-665
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• 2002

In Korea, an olive flounder is very popular fish food item. However, due to the increasing human population, the present catches of the olive flounder may not be sufficient to satisfy the present demand. To increase the supply of the olive flounder, aquaculture has been begun. An interest in the aquaculture of the olive flounder has been increased recently because of its characteristics of good growth and high price in the market, However, the productivity of the olive flounder aquaculture depends on economic inputs such as fuels, facilities, and labor. The rapid growths of the olive flounder aquaculture and the concerns about economic and ecological sustainability have focused peoples attention on the aquaculture industry. In this study, an energy systems model was built to simulate the variation of sustainability on the aquaculture of olive flounder, The results of simulation based on calibration data in 1995 show that olive flounder production yield and asset slowly increase to steady state because of the law of supply and demand. The results of simulation based on the variation of oil price show that the more increase the oil price, the more decrease the olive flounder economic yield and asset. Energy sources required for systems determine the sustainability of systems. Conclusionally, the present systems of the olive flounder aquaculture should be transformed to ecological-recycling systems or ecological engineering systems which depend on renewable resources rather than aquaculture systems which depend on fossil fuels, and be harmonized with the fishing fisheries by the sustainable use of renewable resources in the carrying capacity.

• Mycobiology
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• v.45 no.4
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• pp.297-311
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• 2017

Saprolegniasis is one of the most devastating oomycete diseases in freshwater fish which is caused by species in the genus Saprolegnia including Saprolegnia parasitica. In this study, we isolated the strain of S. parasitica from diseased rainbow trout in Korea. Morphological and molecular based identification confirmed that isolated oomycete belongs to the member of S. parasitica, supported by its typical features including cotton-like mycelium, zoospores and phylogenetic analysis with internal transcribed spacer region. Pathogenicity of isolated S. parasitica was developed in embryo, juvenile, and adult zebrafish as a disease model. Host-pathogen interaction in adult zebrafish was investigated at transcriptional level. Upon infection with S. parasitica, pathogen/antigen recognition and signaling (TLR2, TLR4b, TLR5b, NOD1, and major histocompatibility complex class I), pro/anti-inflammatory cytokines (interleukin $[IL]-1{\beta}$, tumor necrosis factor ${\alpha}$, IL-6, IL-8, interferon ${\gamma}$, IL-12, and IL-10), matrix metalloproteinase (MMP9 and MMP13), cell surface molecules ($CD8^+$ and $CD4^+$) and antioxidant enzymes (superoxide dismutase, catalase) related genes were differentially modulated at 3- and 12-hr post infection. As an anti-Saprolegnia agent, plant based lawsone was applied to investigate on the susceptibility of S. parasitica showing the minimum inhibitory concentration and percentage inhibition of radial growth as $200{\mu}g/mL$ and 31.8%, respectively. Moreover, natural lawsone changed the membrane permeability of S. parasitica mycelium and caused irreversible damage and disintegration to the cellular membranes of S. parasitica. Transcriptional responses of the genes of S. parasitica mycelium exposed to lawsone were altered, indicating that lawsone could be a potential anti-S. parasitica agent for controlling S. parasitica infection.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.58-66
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• 2009

The telemetry of eight adult manchurian trouts (Brachymystax lenok tsinlingensis) in the upper part of the Nakdong River, which is the southern limit of distribution of manchurian trout on the Korean peninsula, was used to examine migration patterns and evaluate characteristics of over-wintering and the spawning season between December, 2007 and May, 2008. Based on the tracking data, the tagged fish showed a limited migration between adjacent pools, moving only up to $8.6m\;day^{-1}$ during the winter season (December to February). Hydraulic conditions of over-wintering pool areas were, ca. 1m depth, slow moving surface water with areas of sand and gravel. The migration of tagged individuals was successful, moving up to $96.2m\;day^{-1}$ during the spawning season. Two tagged individuals (BL4, BL6) exhibited upstream migration, whereas others showed downstream movements. The timing of upstream migration of the two individuals was consistent with an increasing phases of water level and discharge. The fishes migrating toward the down stream moved to the wide pool areas downstream, where they spent the summer season for the growth.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.385-389
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• 2002

Analytical method for diethylstibestrol (DES) and zeranol, which are growth promoters, in muscle foods was studied. Through selected ion monitoring analysis by GC-MSD for hormones, $M^+$ 412, 420, 416, and 433 for DES, $D_8DES$, ${\beta}-estradiol$, and zeranol, respectively, were selected for quantitative analysis. Removal of interferences in meat was done by passing the meat through 1 cc of strong anion exchanges resin, Dowex $2{\times}8$, 400 mesh, whereby the recoveries of DES and zeranol were achieved. Recoveries of DES and zeranol were ranged from 85 to 110%, and 75 to 110%, respectively, in meat using $D_8DES$ as an internal standard, while were 82 to 105%, and 65 to 120%, respectively, using ${\beta}-estradiol$ as an internal standard. These results show that both $D_8DES$ and ${\beta}-estradiol$ can be adopted as the internal standard for the analysis of DES and zeranol in muscle foods. Limits of detection of DES and zeranol were 0.05 and 1.0 ng/g, and limits of quantitation were 0.5 and 1.0 ng/g, respectively. The results of this study revealed no DES and zeranol were present in 14 samples of beefs, porks, ducks, chickens, mutiplicated flat fish, and trout.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.669-673
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• 1999

The effect of delayed initial feeding (1, 3, 5, 7 days) and starvation on morphological change, mortality and cannibalism on larvae of Siniperca scherzeri was examined by laboratory rearing. The larvae of S. scherzeri began to feed on Artemia nauplii at 4 days after hatching. In case of unfed and 7-days delayed groups, all of the larvae died at 12 days after hatching. The larvae of 1 day delayed feeding survived and grew as almost same as the control group, and 3-days delayed groups showed $33\%$ survival rate at the end of experiment (12 days after hatching). In case of the unfed group, total length of the starved larvae showed lower growth rate than the control group, and they did not reached at the same size of the larvae of the control group. Cannibalism were more common in the unfed group and the delayed fed group than the control group. The highest rate of daily mortality caused by cannibalism in the delayed fed group was $23\%$ at 8 days after hatching.

• Korean Journal of Ichthyology
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• v.30 no.4
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• pp.238-241
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• 2018

The purpose of this study was to investigate color pattern and growth in cross progenies between kois and red common carp (Cyprinus carpio). Coverage of red color patches in skin was investigated in $koi{\times}koi$ (KK), $koi{\times}red$ common carp (KR) and red common $carp{\times}koi$ (RK) progenies in 170 days post-hatching (DPH) by analysis of digital photographs. KR cross group had higher length (P<0.05) and the mean weight than in the KK but there were no significant difference between KR and RK. All groups consisted of three color pattern white, white-red and red. The percentage of red-area coverage in skin was 64% in KK progenies, 56% in KR and 36% in RK. The red coverage (30~50%) was highly in KR (15%) than in KK (10%) and RK (12%). The application of red-area body coverage analysis may suggest potentially useful tool for ornamental fish selection.

• Journal of Korean Society on Water Environment
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• v.38 no.1
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• pp.19-30
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• 2022

Climate change has increased the average air temperature. Rising air temperature are absorbed by water bodies, leading to increasing water temperature. Increased water temperature will cause eutrophication and excess algal growth, which will reduce water quality. In this study, long-term trends of air and water temperatures in the Han-river basin over the period of 1997-2020 were discussed to assess the impacts of climate change. Future (~2100s) levels of air temperature were predicted based on the climate change scenarios (Representative concentration pathway (RCP) 2.6, 4.5, 6.0, and 8.5). The results showed that air and water temperatures rose at an average rate of 0.027℃ year^-1 and 0.038℃ year^-1 respectively, over the past 24 years (1997 to 2020). Future air temperatures under RCP 2.6, 4.5, 6.0, and 8.5 increased up to 0.32℃ 1.18℃, 2.14℃, and 3.51℃, respectively. An increasing water temperature could dissolve more minerals from the surrounding rock and will therefore have a higher electrical conductivity. It is the opposite when considering a gas, such as oxygen, dissolved in the water. Water temperature also governs the kinds of organisms that can live in rivers and lakes. Fish, insects, zooplankton, phytoplankton, and other aquatic species all have a preferred temperature range. As temperatures get too far above or below this preferred range, the number of individuals of the species decreases until finally there are none. Therefore, changes of water temperature that are induced by climate change have important implications on water supplies, water quality, and aquatic ecosystems of a watershed.

• Journal of Korea Water Resources Association
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• v.56 no.3
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• pp.225-233
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• 2023

Urban rivers and their surrounding environments have been altered due to factors such as rapid economic growth and urban development. This alteration have caused the rivers to lose their original value and become exposed to various pollution, resulting decrease in citizens' quality of life. This study aims to estimate citizens' Willingness To Pay (WTP) for water quality improvement in Suyeong River in Busan. To estimate the non-market value of the Suyeong River, the WTP of Busan citizens for water quality improvement was estimated, applying Contingent Valuation Method (CVM). The WTP for improving the water quality from Grade 4(polluted water) to Grade 2(game fish like bass can live in it) was estimated using the water quality ladder concept of the US Environmental Protection Agency, assuming annual donations for five years. For the CVM, the logistic distribution and Spike Model were adopted. As a result, citizens residing in the surrounding area of Suyeong River expressed a higher WTP. Considering more than half of the Busan citizens are aware of the "conservation of nature and ecosystems" as a major function of the Suyeong River, this higher WTP could serve as a basis for improving the value of urban rivers.