• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.889-894
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• 1998

This study was designed as a part of efforts to investigate the biochemical pollutant markers for diagnosis of marine pollutions by changes in oxygen radicals and their scavenger enzymes of the flounder (Paralichthys olivaceus) in the South Sea of Korea. Protein contents in brain and muscle of cultured flounder in the South Sea were remarkably lower ($19\~42\%$ and $25\~41\%$, respectively) than those of wild flounder in Pohang of the East Sea as a control group. Lipid Peroxide (LPO) levels in serum of cultured in the South Sea were considerably higher ($5\~33\%$) Elan those of wild flounder in Pohang. Hydroxyl radical formations in serum of cultured flounders in the South Sea were lower ($4\~25\%$) than those of wild flounders in Pohang. Superoxide dismutase (SOD) activities in serum of cultured flounders in South Sea were also significantly lower ($7\~31\%$) than those of wild flounders in Pohang. It is believed that significant decrease of protein contents in brain and muscle, and remarkable increases of LPO in serum of cultured flounders may be used as a biochemical pollutant markers for diagnosis of marine pollutions. These results suggest that near-coastal water as well as neritic water of the South Sea might be affected by pollutant input as well as the Yellow Sea of Korea.

• Journal of Aquaculture
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• v.15 no.1
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• pp.15-21
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• 2002

Two groups of juvenile flounders (90 g/each) were fed on moist pellet feed thrice a day for a period of 8 weeks; the first group, reared in 4 circular (6m $\times$ 0.8 m) tanks (1200 flounders/tank), was fed daily (ED) and the second one on alternate days (EO). There was no significant difference in growth and feed conversion ratio (FCR) between these groups. There was also no difference in chemical composition, except in lipid, which was significantly higher (4.1%) in the ED group than the EO group (3.4%). Food intake and gain in the whole body nitrogen (N) were higher in the ED group but there was no significant difference between these groups in N retention; they excreted almost equal amount (114 vs 112 g) of N. Although phosphorus intake was significantly different between these groups, the flounders retained equal amount (0.5 g) of P in their body and excreted also equal amount (27.6 vs 26.0 g/kg weight gain) of p. Energy intake (2528 kJ) of the ED group was higher than that (2116 kJ) of the EO group. However, there was no significant difference in their energy retention efficiency. Clearly, alternate day feeding regimen led to more efficient utilization of food by the juvenile flounder.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.882-888
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• 1998

This study was designed as a part of efforts to investigate the biochemical pollutant markers for diagnosis of marine pollutions by changes in lipid components of the flounder (Paralichthys olivaceus) in the South Sea of Korea, Hemoglobin levels in serum of cultured flounders in the South Sea were lower ($4\~17\%$) than those of wild flounder in Pohang as a control group. Triglyceride (TG), Total and low density lipoprotein (LDL)-cholesterol contents in serum of cultured flounders in the South Sea were $12\~25\%,\;9\~19\%$ and $17\~25\%$ respectively which are higher than those of wild flounder in Pohang. Atherogenic index (AI) and T-Chol/PL ratios in serum of cultured flounders in the South Sea were significantly higher($26\~43\%$ and $17\~26\%$ respectively) than those of wild flounder in Pohang. These results suggest that near-coastal water as well as neritic water of the South Sea might be affected by pollutant input as well as the Yellow Sea of Korea.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.495-500
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• 2015

Currently the fish aquaculture industry of Korea is focused on the mass culture of flatfish (Paralichthys olivaceus) and and rockfish (Sebastes schlegeli) with completely controlled culture techniques. Recently, there has been considerable interest in new species development, such as the starry flounder (Platichthys stellatus). The value of starry flounder (Platichthys stellatus) as a raw fish increases with time because it is tasty, light, and bouncy. In this paper, the growth characteristics dependent on the LED wavelengths and the optimal growth conditions of the starry flounder were studied. In these experiments 4 different kinds of LED lighting, configurations were designed and prepared using red, green, blue and white, respectively. The fish aquaculture experiments were conducted over 10 weeks in four fish tanks, each installed with a different color of LED lighting. 10 starry flounders of 13 ~ 17g were placed into each tank. The effects of each color of light on the growth rate of the starry flounders were then examined. As a result, the starry flounders under the green LED lighting showed the highest growth rate, followed by the white, red, and blue LED lighting. Based on these results, a green light provides a suitable breeding environment for the starry flounder.

• Development and Reproduction
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• v.17 no.4
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• pp.321-327
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• 2013

The innate immune system is the only defense weapon that invertebrates have, and it is the fundamental defense mechanism for fish. The innate immune response is important in newly hatched flounders because it is closely involved in the initial feeding phase, which is why it is essential for survival during the juvenile period. The expression analysis of genes involved in the innate immune response in the olive flounder (Paralichthys olivaceus) in the days after hatching is incomplete. Therefore, we have begun to examine the expression patterns of genes specifically induced during the development of the innate immune system in newly hatched flounders. Microscopic observation showed that pronephron formation corresponded with the expression of perforin-encoding gene. These results suggest that perforin plays a vital role in the innate immunity of the kidney during developmental stages. Perforin expression was strong at the start of the development of the innate immune response, and continued throughout all the development stages. Our findings have important implications with respect to perforin's biological role and the evolution of the first defense mechanisms in olive flounder. Further studies are required to elucidate the perforin-mediated innate immunity response and to decipher the functional role of perforin in developmental stages.

• Development and Reproduction
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• v.17 no.3
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• pp.231-240
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• 2013

Olive flounder (Paralichthys olivaceus) is one of the commercial important flatfish species in Korea. The ocular signal transduction pathway is important in newly hatched flounders because it is closely involved in the initial feeding phase thus essential for survival during the juvenile period. However, the study of gene expression during ocular development is incomplete in olive flounder. Therefore we examined the expression analysis of specifically induced genes during the development of the visual system in newly hatched flounders. We searched ocular development-involved gene in the database of expressed sequence tags (ESTs) from olive flounder eye and this gene similar to arrestin with a partial sequence homology. Microscopic observation of retinal formation corresponded with the time of expression of the arrestin gene in the developmental stage. These results suggest that arrestin plays a vital role in the visual signal transduction pathway of the retina during ocular development. The expression of arrestin was strong in the ocular system during the entirety of the development stages. Our findings regarding arrestin have important implications with respect to its biological role and evolution of G-protein coupled receptor (GPCR) signaling in olive flounder. Further studies are required on the GPCR-mediated signaling pathway and to decipher the functional role of arrestin.

• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.114-119
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• 2003

Effects of Aroclor 1254, on hematological disturbance were investigated in the olive flounder, Paralichthys olivaceus. Flounders were exposed to waterborne PCB (3.0${\mu}g \; L^{-1}$) for 00 days. Blood samples were taken to determine their hematological disturbances. Plasma calcium concentration was significantly decreased in PCBs exposed flounder compared to the control group, while magnesium and inorganic phosphorus concentrations in PCBs exposed flounders were not significantly influenced during the test Belied. Although plasma total protein and albumin level were significantly reduced compared to the control group after 40 days, plasma glucose level was found to be significantly increased over the control group. Exposure to waterborne PCBs resulted in significant increase in the various enzyme activities, such as GOT, GPT and ALP in the flounder. The results of the present study led us to conclude that concentration of PCBs 3.0${\mu}g \; L^{-1}$ of the estuarine could markedly affect the hems tological distribution of olive flounder, Paralichthys olivaceus.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.2
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• pp.157-162
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• 2018

A feeding trial was conducted to investigate the effects of supplementation with four phosphorus (P) additives [mono-calcium phosphate (MCP), dicalcium phosphate (DCP), tricalcium phosphate (TCP) and magnesium hydrogen phosphate (MHP)] on the growth, feed utilization and whole body mineral composition of juvenile olive flounders Paralichthys olivaceus. A basal diet without P supplementation was prepared as a negative control and four supplemental P sources were added at a level of 2%. Triplicate groups of fish (initial mean body weight 11 g) were fed one of the experimental diets to apparent satiation twice a day, at 08:30 and 18:00 for 10 weeks. The final body weights of fish fed the experimental diets ranged from 29.4 g (DCP) to 34.2 g (MCP) and did not differ significantly (P>0.05) among treatments. Similar tendencies were found for all parameters including weight gain (%), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), feed intake (FI) and survival rate (SR). The hematocrit (%), hemoglobin (g/dL), serum inorganic P and whole body mineral composition did not differ significantly different (P>0.05) among the treatments. Therefore, dietary P addition is not necessary for juvenile olive flounder fed a fish meal-based diet.

• Fisheries and Aquatic Sciences
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• v.21 no.6
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• pp.17.1-17.7
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• 2018

This study investigated the trend in emaciation infection outbreak in olive flounder (Paralichthys olivaceus) of Jeju island, South Korea, during 2014-2015. A total of 900 fish were systematically examined by PCR method using the EM-F/EM-R primer set in April, May, September, November, and December 2014, and the infection rate was recorded. In 2015, the same examination was conducted in March, May, July, and October but with 660 fish. It was found that the infection rate was 18.3~71.6% in 2014, which increased to 16.3~90.3% in 2015. Furthermore, September and December in 2014 and March, July, and October in 2015 showed a relatively higher infection rate. According to the infection trend analysis, which depended on the sample size, the infection occurred in all of fish sizes in this study and 11~30 cm fish group showed the highest infection rate. Histological examination confirmed that the kidney areas of the emaciating infected olive flounder contained several spores of $4{\sim}9{\mu}m$, and in severe cases, the elimination and destruction of tissue were confirmed by PCR. Thus, an important portion of farmed olive flounders in the Jeju region suffers from emaciation disease. This epidemiological survey serves as a useful reference on the emaciation disease of cultured olive flounders in Jeju

• Development and Reproduction
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• v.18 no.4
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• pp.233-240
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• 2014

The early growth response protein 1 (Egr-1) is a widely reported zinc finger protein and a well known transcription factor encoded by the Egr-1 gene, which plays key roles in many aspects of vertebrate embryogenesis and in adult vertebrates. The Egr-1 expression is important in the formation of the gill vascular system in flounders, which develops during the post-hatching phase and is essential for survival during the juvenile period. However, the complete details of Egr-1 expression during embryo development in olive flounder are not available. We assessed the expression patterns of Egr-1 during the early development of olive flounders by using reverse transcription polymerase chain reaction (RT-PCR) analysis. Microscopic observations showed that gill filament formation corresponded with the Egr-1 expression. Thus, we showed that Egr-1 plays a vital role in angiogenesis in the gill filaments during embryogenesis. Further, Egr-1 expression was found to be strong at 5 days after hatching (DAH), in the development of the gill vascular system, and this strong expression level was maintained throughout all the development stages. Our findings have important implications with respect to the biological role of Egr-1 and evolution of the first respiratory blood vessels in the gills of olive flounder. Further studies are required to elucidate the Egr-1-mediated stress response and to decipher the functional role of Egr-1 in developmental stages.