• Journal of Marine Life Science
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• v.8 no.1
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• pp.32-42
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• 2023

Fish reproduction is regulated by various neurohormones secreted from the brain and gonadotropic hormones secreted from the pituitary. Reproduction of eel (Anguilla japonica) is also regulated by these hormones. However, how the neurohormones regulate the secretion of pituitary hormones during sexual maturation is not completely understood. Previous studies have shown that neurohormones such as progesterone (P4), melatonin and serotonin (5-HT) are involved in the regulation of reproductive processes in some fish. In this study, the eel pituitary was primary cultured, and stabilized pituitary cells were treated with P4, 17β-estradiol (E2), melatonin, or 5-HT. The effect of these treatments on the expression of FSHβ, LHβ, GH and SL mRNA was, then, investigated. P4 increased the expression of FSHβ and LHβ in pituitary cells, and melatonin increased the expression of GH and SL as well as FSHβ and LHβ. However, 5-HT did not significantly affect the expression of these mRNA. These results suggest that P4 and melatonin may play some important roles in the early sexual maturation of eels.

• Journal of fish pathology
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• v.36 no.2
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• pp.239-250
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• 2023

Disease monitoring was conducted to investigate the recent disease occurrence in Japanese eels (Anguilla japonica). Between May 2021 and March 2022, an investigation was conducted on eels from seven farms experiencing mortality. JEECV (Japanese eel endothelial cells-infecting virus) was detected in all examined farms, each exhibiting co-infections with 1 or 2 bacteria, including Edwardsiella anguillarum, E. piscisida, Aeromonas sp., Citrobacter freundii, Lactococcus garviae, or Vibrio sp. From March 2022 to October 2023, monthly periodic inspections were carried out at a farm in Yeonggwang, Jeollanam-do, for a total of 22 times. JEECV was detected in 10 out of 22 times, even when mortality was not recorded. Bacteria such as E. anguillarum, C. freundii, Aeromonas sp., and Vibrio sp. were isolated, but consistent clinical signs of liver abscess and hemorrhagic lesions were only recognized in fish infected with E. anguillarum. Other bacteria were often isolated from apparently healthy fish. In conclusion, mortality in eel farms frequently occurs due to co-infections of JEECV with bacteria rather than JEECV alone. Therefore, to reduce eel mortality, it is crucial to decrease co-infections, with a particular emphasis of JEECV and E. anguillarum.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.05a
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• pp.553-554
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• 2002

• Korean Aquaculture
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• v.16 no.2
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• pp.21-34
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• 2004

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1995.06a
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• pp.159-164
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• 1995

• IMMUNE NETWORK
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• v.8 no.4
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• pp.124-129
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• 2008

Background: The immunomodulatory effects of Korean mistletoe (Viscum album Coloratum) on the innate immune responses of eel (Anguilla japonica) were studied. Methods: Mistletoe, Freund’s complete adjuvant (FCA), or phosphate-buffered saline (PBS) as a control was injected into eel peritoneal cavities. Results: Nitroblue tetrazolium (NBT)-positive cells in the head kidney of eel were significantly augmented by the second day post-injection of mistletoe. Reactive oxygen intermediates (ROI) were more produced in mistletoe-injected fish kidney leucocytes than in FCA-injected ones. The level of lysozyme activity in the serum of fish 2 days after injection with mistletoe was also significantly higher than that in the serum of the control fish. The optimal concentration of mistletoe in inducing the highest serum lysozyme activity was revealed to 500${\mu}$g/200 g of fish. In phagocytic activity assay, mistletoe-sensitized eel kidney phagocytes captured more zymosan than did the control fish. Conclusion: Korean mistletoe appeared to be a good activator of the non-specific immune responses of eel.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.3
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• pp.317-320
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• 2003

Morphologically similar fish species were subjected to the random amplified polymorphic DNA (RAPD) analysis using universal rice primer (URP). The fish species tested were sea basses (Lateolabrax japonicus and L. maculatus), eels (Anguilla japonica, A. bicolor bicolor, A. rostrata, and A. anguilla), and flounders (Limanda yokohamae and L. herzensteinin). Highly reproducible RAPD patterns were observed with several potential species-specific markers. The results indicate that RAPD technique using URP is useful for distinguishing fish psecies in a rapid manner.

• YAKHAK HOEJI
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• v.22 no.1
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• pp.42-50
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• 1978

The plasma proteins of fresh water fishes have been fractionated by disc electrophoresis in acrylamide gels utilized as an electrophoretic supporting medium. The species of fishes examined in this experiment were Anguilla japonica, Misgurnus mizolepis, Parasilurus asotus, Siniperca scherzeri, Pelteobagrus fulvidra, Carassius carassius, Cyprinus carpio, and Hemibarbus labeo, obtained in the Han River. Disc electrophoresis was performed as described by Ornstein and Davis. Gels and buffer solution were prepared by the method developed by W.J.Kim. The separation gels were 7% acrylamide gel. The fractionation of plasma proteins showed 13 bands in Anguilla japonica, 10 in Misgurnus mizolepis, 15 in Parasilurus asotus, 12 in Siniperca scherzeri, 11 in Pelteobagrus fulvidra, 13 in Carassius carassius, 9 in Cyprinus carpio, and 13 in Hemibarbus labeo. The patterns of plasma protein on the each species of fishes were different in the number of bands, ratio of contents, relative mobilities, and forms of fractionation.

• Toxicological Research
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• v.13 no.3
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• pp.209-213
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• 1997

Residue and recoveries of clindamycin were investigated by reversed-phase high performance liquid chromatography (RP-HPLC) which was infected for the control of streptcoccal infection in Anguilla japonica and Paralichthys olivaceusis. Detection limit was 0.1 ppm. Recoveries of clindamycin in muscles of flounder and eel were 80.4 and 78.8%, respectively. The clindamycin in eel and flounder was detected up to 13 and 15 days after dosing, respectively.

• The Korean Journal of Zoology
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• v.36 no.4
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• pp.545-555
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• 1993

뱀장어속(Anguilla)의 뱀장어(A. ioponica)와 무태장어(A. marmoruta) 및 꾀붕장어(Anago anogo)의 유전적 특징과 종간 유연관계를 밝히기 위하여 isozyme 분석과 mtDNA 분석을 실시하였다. Isozyme 분석결과 20개의 효소 및 비효소단백질에서 총 39개의 유전자를 검출하였고 각종 특유의 genetic marker를 확인하였다. 3종의 평균 유전적 변이는 뱀장어가 HD=0.057. HG=0.065, 무태장어는 HD=0.067 HG=0.053, 체불장어가 HD=0.018. HG=0.020으로 각각 나타났다. 뱀장어와 무태장어의 평균 종간유전적 근인관계는 S=0.420 (D=0.869)로 멀게 나타났다. 6 base를 인지하는 10종류의 제한효소를 처리한 결과 mtDNA 절편양상은 각 종내에서 동일하게 나타났으나 각종간에 차이를 보였고, 종간 평균염기 치 환율은 뱀장어와 무태장어가 p=3.4%, 뱀장어속 2종과 꾀붕장어는 p=9.6%로 나타났다.