• 대한수의학회지
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• 제46권1호
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• pp.21-25
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• 2006

Iridovirus is an icosahedral cytoplasmic double-stranded DNA virus with a genome size of 170-200kb. Outbreaks of fish iridovirus infection are characterized by their wide geographic distribution and broad host spectrum, especially in water temperatures of $25-27^{\circ}C$ Recently, the causative agent of high mortalities in flounder (Paralichthys olivaceus) was identified as fish iridovirus in Korea. Iridoviral infection repeatedly occurs in the same area for long periods, suggesting the possibility of viral infection in nursery. To examine this, the existence of iridovirus in juvenile flounders was detected by PCR using virus-specific primers. Antibodies induced against this virus were also examined using ELISA. As a result, juvenile fish in nursery were found to be previously infected with iridovirus, suggesting that proper prevention systems are required.

• Fisheries and Aquatic Sciences
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• 제7권1호
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• pp.29-33
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• 2004

The potential of phenanthrene to induce xenobiotic responses was investigated. Olive flounder (Paralichthys olivaceus) was exposed to different levels of phenanthrene $(0.5,\;1\;and\;{\mu}M)$ for 4 weeks, Gill CYP450 content and EROD (ethoxyresorufin O-deethylation) activity were found to be significant in the flounders treated with the higher concentration of phenanthrene $(>1.0\;{\mu}M)$, however, there were no significant changes in gill PROD (penthoxyresorufin O-deethylation) activity in all treated group compared to the controls. This study demonstrated that phenanthrene has potential to induce gill cytochrome P450 and EROD enzyme in olive flounder.

• Fisheries and Aquatic Sciences
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• 제26권3호
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• pp.234-240
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• 2023

Enteromyxum leei has been identified as the causative agent of emaciation disease in a wide range of marine fish hosts. In this study, we aimed to determine the effect of the parasitic infection of Enteromyxum species on starry flounder that were cultured in aquaculture farms of Jeju island in Korea. As the mortality of cultured olive flounder Paralichthys olivaceus because of E. leei infection increased, some fish farms on Jeju island attempted to culture the starry flounder Platichthys stellatus, as an alternative. Myxosporeans with a developmental stage similar to E. leei were found in the intestines of cultured starry flounders. The partial 18S rDNA of myxosporeans showed 100% similarity with E. leei. To reveal the effect of E. leei infection on starry flounder, the intensity of E. leei infection measured using quantitative polymerase chain reaction, and the condition factor (CF) of fish were measured and analyzed statistically. The results showed that high-intensity E. leei infection significantly decreased the CF of the starry flounder. However, the pathogenicity of E. leei to starry flounder is low, considering its mortality and clinical signs.

• 한국양식학회지
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• 제13권3호
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• pp.223-230
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• 2000

사육수에 광물미립자를 현탁시켜 노폐물을 흡착, 분해시킨 후 이를 분리, 배출시킴으로서 사육수를 정화시켜 재 사용할 수 있다는 가설 하에 사육수조와 포말분리장치로만 구성된 사육수 재사용 시스템에서 광물미립자를 현탁시켜 넙치를 실험사육 하였다. 두 종류의 가공황토 (processed residual reddish soil, 50 $\mu$ 이하)와 돌로마이트 (dolomite, 50 ${\mu}$이하) 미립자를 사육수에 현탁시키고 포말분리장치로 이를 분리, 배출시킴으로서 사육수를 정화하였다. 직경 4.8 m의 원형사육수조(사육수량 10 $m^2$), 사육수 순환을 시간당 2회전, 재사용을 90%, 수온 17${\pm}$1$^{\circ}C$에서 평균체중 23.1 g의 넙치 치어(5,555마리, 총중량 128 kg)를 75일간 사육하여 평균체중84.6 g (5,532마리, 총중량 468 kg)으로 육성하였다. 최종수용밀도는 26.0 kg/$m^2$였다. 실험기간 동안 어병은 관찰되지 않았다. 사육수에 광물입자를 현탁시켜 사육수 중의 노폐물을 흡착, 분해시킨 후 포말분리장치로 이를 배출시킴으로서 사육수를 정화하여 재사용하는 방법은 새로운 사육수 재사용 어류양식시스템으로서 가능성이 있다.

• 한국수산과학회지
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• 제42권3호
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• pp.215-223
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• 2009

This study was conducted to investigate the effect of diets supplemented with different levels (0, 2.5, 5.0, and 7.5%) of yuza (Citrus junas Sieb ex Tanaka) on nutritional composition of olive flounder. Four groups of fish (242.2$\pm$14.2 g) were fed to apparent satiation twice daily for 4 months. There were no significant differences in proximate composition among the treatment groups (P<0.05). Vitamin C content in flounder muscle was higher in the yuza-added groups than in the control group, and the content among the treatment groups increased as amount of yuza added to diets increased (P<0.05). Of the eight organic acids in flounder muscle, lactic acid was predominant, followed by oxalic acid, succinic-acid, tartaric acid, and acetic acid. Flounders fed 2.5% yuza diet had the highest lactic acid content of all treatments. Four sugars were found in all groups and glucose was the major sugar. Glucose and ribose were detected as the highest sugars in the 2.5% treatment, while maltose and galactose were the dominant sugars in the 5.0% treatment. The abundant fatty acids in fed flounders were 22:6n-3 (DHA), 16:0, and l8:1n-9, which were composed of over 60% of total fatty acids. The control and the 7.5% treatment group had higher 22:6n-3 (DHA) content than the other groups. Major amino acids in samples were glutamic acid, aspartic acid, lysine, leucine, valine, arginine, and alanine. The 2.5% yuza treatment had the highest content of total amino acids and essential amino acids. There were little differences in the free amino acid compositions among the treatments. However, taurine was the predominant amino acid and made up over 47% of total free amino acids. The 2.5% added yuza group contained higher amount of sweet amino acids such as alanine, serine, proline, glycine than the other groups. The addition of yuza to diet of olive flounder had no or little effect on the nutritional components of olive flounder except for vitamin C. However, the 2.5% yuza added group had the highest nutritional values of the treatment groups.

• Fisheries and Aquatic Sciences
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• 제17권3호
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• pp.325-337
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• 2014

To assess the functional structure of prepro-melanin-concentrating hormone (pMCH), we isolated and cloned pMCH (of-pMCH) mRNA from the brain of the olive flounder, Paralichthys olivaceus, and compared its amino acid sequence with those from other animals. In addition, to examine whether activation of the brain of-pMCH gene is influenced by background color, density, and feeding, we compared pMCH mRNA activities against different background colors (bright and dark) and at different densities (100% PCA and 200% PCA). To examine whether the pMCH gene is related with malpigmentation of blind-side skin and appetite, we compared pMCH gene expression between ordinary and hypermelanic flounders, and between feeding and fasting flounders. The of-pMCH cDNA was 405 bp in the open reading frame [ORF] and encoded a protein of 135 amino acids; MCH was 51 bp in length and encoded a protein of 17 amino acids. An obvious single band of the expected size was obtained from the brain and pituitary by RT-PCR. In addition, of-pMCH gene activity was significantly higher in the bright background only at low density (< 100% PCA) making the ocular skin of fish whitening, and in ordinary fish. However, the gene activity was significantly decreased in dark background, at high density (>200% PCA), and in hypermelano fish. These results suggest that skin whitening camouflage of the flounder is induced by high MCH gene activity, and the density disturbs the function of background color in the physiological color change. Moreover, our data suggest that a low level of MCH gene activity may be related to malpigmentation of the blind-side skin. In feeding, although pMCH gene activity was significantly increased by feeding in the white background, the pMCH gene activity in the dark background was not influenced by feeding, indicating that the MCH gene activity increased by feeding can be offset by dark background color, or is unaffected by appetite. In conclusion, this study showed that MCH gene expression is related to ocular-skin whitening camouflage and blind-skin hypermelanosis, and is influenced by background color and density.

• 한국임상수의학회지
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• 제26권3호
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• pp.226-230
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• 2009

We evaluated the efficacy of $\beta$-hemolytic Streptococcus(S.) iniae vaccine on cultured olive flounder. Three hundred flounders(weight $50{\pm}5$ g) were obtained from two farm at Wando and Taean in the southern and western coast of Korea at May and June 2007, respectively. Twenty of flounders moved in 0.5 tons aquaria in land-marine tank system of National Veterinary Research and Quarantine Service. Seawater was transported from the sea of Inchon in western Korea, and water temperature maintained to $22^{\circ}C$ and $25^{\circ}C$ during the vaccination and challenge test, respectively. We used the formalin-inactivated $\beta$-hemolytic S. iniae vaccine produced by domestic manufacturers. The vaccine was intraperitoneally administered to fish. The vaccinated and control group were challenged with intraperitoneal injection by virulent S. iniae SI-36 isolates with $5.0{\times}10^8$ CFU/fish at 3 weeks after vaccination. We evaluated the vaccine efficacy by calculating numbers of dead fish, and observing of clinical signs, exterior and gross lesions, and examining bacteria isolation and identification. Thirty-four(25.2%) of 135 control and vaccinated group fish were dead with serious anemia, abdominal extension, and hernia of intestine during 3 weeks post vaccination. We isolated Neoheterobothrium hirame from the buccal cavity and Edwardsiella tarda from kidney of dead and diseased fish. When infected fish with these agents were challenged with S. iniae SI-36 isolates, the cumulative mortality of control and vaccinated group were 86.7, and 46.7%, respectively. However, significant differences(p<0.05) were observed on cumulative mortality between control(20.0%) and vaccinated group(95.0%) at second trials with 40 healthy, and relative percent survival(RPS) was 78.0%. We confirmed that the efficacy of $\beta$-hemolytic S. iniae vaccine on olive flounder were impacted by health condition such as bacterial and parasitic diseases.

• 한국해양바이오학회지
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• 제1권3호
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• pp.218-223
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• 2006

어류의 세균성질병 원인체인 Edwardsiella tarda 감염의 예방과 치료에 E. tarda로 면역한 계란으로부터 얻어진 난황항체 (IgY)의 잠정적인 사용을 평가하였다. PEG법으로 정제된 IgY는 64 kDa의 heavy chain과 27 kDa의 light chain을 가지고 있었다. IgY는 사료 공급 후 위의 pH가 3.4로 낮아지는 2시간째에는 대부분의 활성을 상실하였으나, 장내에서는 IgY의 활성이 나타났다. IgY의 효능 실험 결과 감염 초기에 IgY를 20 mg/fish로 공급한 그룹은 모든 실험에서 대조 그룹에 비해 높은 생존율을 나타내었으며, 장기 내에서 균의 감염 정도 역시 낮았다. 그러나 감염 후기에서는 생존율에 있어서의 유의적인 차이를 확인하기 힘들었다. 이는 넙치의 위에서 대부분의 IgY가 활성을 잃어 낮은 농도만이 장으로 이동하기 때문일 것으로 사료되며, 이 농도에서 IgY는 E. tarda에 대한 뚜렷한 예방이나 치료의 효과 보다는 감염시기를 어느 정도 연장시키는 역할을 하는 것으로 추정된다.

• 한국해양생명과학회지
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• 제7권2호
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• pp.171-179
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• 2022

본 연구는 양식산 참돔과 넙치를 Cochlodinium polykrikoides 적조에 노출시켜 노출 시간에 따른 생존율, 호흡수, 혈중 스트레스 지표 및 조직학적 변화를 비교 조사하였다. 대조구는 자연해수를 사용하였고, 실험구는 C. polykrikoides 밀도를 5,500±200 cells/ml로 설정하였다. 그 결과, 참돔은 적조 노출 1시간 이내, 넙치는 적조 노출 5시간 이내 전량 폐사하였다. 생리학적 반응을 분석한 결과, 참돔은 적조 노출 후 혈중 Glucose 농도가 감소하였으며, 혈중 GOT 및 GPT농도는 증가하였고, 혈중 SOD 농도는 감소하고, CAT 및 GPx 농도는 증가하는 경향을 보였다. 넙치는 적조 노출 후 혈중 Cortisol 및 GOT, GPT 농도가 증가하였고, 혈중 Glucose 농도는 적조 노출 1시간째 증가한 이후 감소하였으며, 혈중 SOD, CAT, GPx 농도는 노출 1시간째 감소한 이후 증가하였다. 조직학적 분석 결과, 참돔과 넙치의 아가미에 구조적인 손상이 발생하였다. 결론적으로 5,500 cells/ml 밀도의 C. polykrikoides 적조 노출은 양식산 참돔과 넙치에게 산화적 스트레스로 작용하여 체내 항산화 방어 기작을 활성화하고, 간과 아가미의 손상을 발생시키는 것으로 나타났다.

• 한국어류학회지
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• 제19권4호
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• pp.365-370
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• 2007

최근 우리나라의 남해 연안에서 출현하고 있는 가자미목 어류 2종을 조사한 결과 지금까지 국내에서 서식이 보고되지 않은 붕넙치과의 Psettina tosana와 넙치과의 Pseudorhombus oculocirris로 동정되었다. P. tosana는 형태적으로 P. gigantea와 P. iijimae와 비슷하나 P. tosana는 가슴지느러미 연조가 9~10이고, 측선린수가 적으며, snout 주변이 검지않아 P. gigantea와 다르고, 새궁의 상지에 새파가 없고, 하악의 치열이 1열인 점이 P. iijimae와는 구별되었다. 한편 P. oculocirris는 P. pentophthalmus에 비하여 측선비늘 수가 많고, 유안측의 전비공만 tubular 타입에 flap이 존재하고, 등지느러미 앞쪽의 유리된 연조가 약간 납작하고, 길다는 점이 특징적이다.