• 한국어병학회지
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• 제30권1호
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• pp.67-70
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• 2017

Pseudomonas is currently causing increasing mortality in farmed olive flounder in Jeju Island. It was previously reported that P. anguilliseptica is the pathogen causing the mortality. It is not known whether other sub-species are involved or not. In this study, P. fluorescens was identified from diseased olive flounder by a PCR-based diagnosis. Based on genomic sequencing and BLAST analysis, 5 out of 6 samples were closer with P. fluorescens than P. anguilliseptica. Our finding suggests that P. fluorescens may be the dominant species causing the disease in farmed olive flounder in Jeju Island, South Korea.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1998년도 공동 심포지엄 및 추계학술발표회
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• pp.156-161
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• 1998

As grouting materials for ground improvement, silicate materials such as water glass, silica-sol and so forth are used worldwide. However, they may pollute underground water. In this study, fish poison test(Korean standard industrial code KS M 0111) which estimates toxicity for fish is applied to evaluate the toxic effect by grouting materials. From the test result of the sample made of LW, LC50(Median Lethal Concentration) reaches within 24 hours. In case of the silica-sol, it does not even in 96 hours. Therefore, we can conclude that the sililca-sol grouting method is more free from the danger of underground water pollution. From the result that the mortality of fish under the condition of pH 8.6 is 0% within 96 hours, the groundwater can be saved by controlling pH below 8.6 for the grouting in the field.

• 한국어병학회지
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• 제16권1호
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• pp.23-30
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• 2003

On September in 1998, a microsporidian infection was recognized in ayu, Plecoglossus altivelis, farmed on Kyongnam province of South Korea. Cumulative mortality was around 10% in 10 days. Infected fish which were piping for air near the surface of the water or in the asphyxic, lethargic condition revealed darkening of body and abdominal distention. Numerous whitish nodules up to 3mm in size were observed throughout most of body organs and tissues including gill, operculum, peritoneal wall and organs. Xenomas were also histologically confirmed in multiple internal organs with the evidences suggesting circulatory disturbance. Based on the morphology of spore and xenoma, and the distribution of xenomas in organs and tissues, this disease was diagnosed to be a microsporidiosis caused by Glugea plecoglossi. The mortality might be deeply related to the local circulatory disturbance by xemonas rather than the mechano-chemical effect of xenomas on adjacent tissues.

• 한국어병학회지
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• 제36권2호
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• pp.395-401
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• 2023

Myxosporeans are widespread cnidarian endoparasites in marine and freshwater ecosystems and several species were reported to be a threat to cultured fish causing serious diseases with mass mortality. In the present study, we found a myxosporean species in the genus Thelohanellus from the gills of the cultured common carp (Cyprinus carpio) fingerling for the first time in Korea. The morphological observation showed 500 ㎛ ~ 1 mm size, oval to circular shaped plasmodia containing spores which are pyriform at the anterior end and round at the posterior end (average size 20.1 ㎛ × 9.1 ㎛), with 5 to 6 turns of a single polar filament located in the polar capsule with an average size of 10 ㎛ × 4.6 ㎛. The 18S rRNA sequence was closest to the sequence of T. wangi among Thelohanellus species infecting gills but was not completely identical. Based on the morphological characteristics and molecular analysis results, we classified the present myxosporean parasite as Thelohanellus sp., temporarily. The prevalence and infection intensity of Thelohanellus sp. in the common carp fingerling were very high, which was thought to be the main cause of high mortality.

• 수산해양교육연구
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• 제28권3호
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• pp.653-660
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• 2016

Snakehead, Channa argus were intraperitoneally infected with Nocardia seriolae. at the concentrations of $1.5{\times}10^7cfu/m{\ell}$ or $1.5{\times}10^8cfu/m{\ell}$. The infected fish were kept in aquaria at $25^{\circ}C$ and $30^{\circ}C$ for 3 weeks. Clinical signs and mortality were monitored daily to evaluate the virulence. All artificially infected fish showed the same clinical sign found in naturally infected fish. All the fish infected with $1.5{\times}10^8cfu/m{\ell}$ of N. seriolae died within 24days. N. seriolae showed higher virulence to snakehead at the temperature $30^{\circ}C$. Internal lesions such as whitish nodules in the infected internal organs were not correlated with mortality but some degenerative changes were observed in all the infected organs within a week. Whitish nodules in the infected organs which are the typical character in nocardial infection was initially found at two weeks after the artificial infection in snakehead.

• 한국어병학회지
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• 제18권2호
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• pp.157-165
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• 2005

2005년 여름에 국내에서 사육되는 가물치에서 대량폐사를 수반하는 새로운 질병이 발견되었다. 감염 어류는 복부팽만과 항문 주위 출혈 이외의 특이한 외부 증상을 나타내지 않았으나 복부를 절개하면 많은 수의 백색 결절이 간, 비장 및 신장을 포함한 내부 장기에서 관찰되었다. 특히 내부 장기의 조직병리학적 관찰에서 granuloma가 관찰되었다. 이들 감염 어류에서 Gram 양성의 사상균이 분리되었다. 분리균은 Nocardia spp.와 non-Nocardia 균의 16S rRNA 염기 분석에 기초한 Nocardia 특이 primer를 사용한 PCR 방법으로 확인하였다. 이것은 어류에서 발생한 Nocardia 감염증의 국내 첫 사례이다.

• 한국수산과학회지
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• 제44권3호
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• pp.225-231
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• 2011

Prolactin (PRL) plays an important role in freshwater (FW) osmoregulation by preventing the loss of ions and the uptake of water in fish. Growth hormone (GH) promotes acclimation to seawater (SW) in several teleosts. We acclimated rainbow trout Oncorhynchus mykiss weighting $68.2{\pm}16.6$, $138.3{\pm}24$, and $287.5{\pm}42.1$ g in separate experiments to SW under slow-acclimation (SSW) or acute-acclimation (ASW) conditions, and then examined the PRL and GH mRNA levels using the real-time quantitative polymerase chain reaction. The PRL mRNA levels in all three experimental groups decreased significantly with both the SSW and ASW treatments, as compared to a control group kept in FW for 30 days. The GH mRNA levels increased with ASW in the largest fish, whereas the levels in the other groups did not change significantly. The mortality rate of the largest fish was lower than for the other groups, whereas the growth rate among the three experimental groups did not differ significantly. The growth rate of the ASW group was highest for the smallest fish. These results suggest that SW acclimation is associated with the gene expression levels of PRL and GH in relatively large rainbow trout. In addition, the fish mortality and growth rate on FW-SW transfer seem to be related to body weight, and the SW acclimation method may be applied to the hatcheries industry.

• 한국발생생물학회지:발생과생식
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• 제24권3호
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• pp.215-224
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• 2020

Seawater adaptability of steelhead trout increases along with the increase in the size of the fish, independent of parr-smolt transformation. Three 96 h seawater challenge tests were conducted to determine the size at which seawater adaptability of steelhead trout develops. Plasma Na⁺ and Cl^- levels, moisture content, gill Na⁺/K⁺ ATPase activity, and mortality during the 96 h after direct transfer to seawater (32 ppt) were determined. Plasma Na⁺ and Cl^- levels in 50 g fish continuously increased during the 96 h after the transfer to seawater (p<0.05), but the levels in 100 and 150 g fish leveled off after 24 h (p<0.05). Both 100 and 150 g size steelhead trout maintained muscle moisture content (%) better than 50 g size fish (p<0.05). Gill Na⁺/K⁺ ATPase activity in the 100 g size group increased in a time-dependent manner after transfer to seawater (p<0.05), whereas activity in the 50 and 150 g sizes did not increase (p>0.05), for which a possible explanation was discussed. A mere 2.6% mortality in both the 50 and 150 g size groups was observed. In conclusion, the current results indicate that 50 g size steelhead trout did not show development of a high level of hypoosmoregulatory capacity, whereas fish in the 100 and 150 g size groups showed a high level in our experimental conditions. Therefore, the steelhead trout larger than a 100 g size is recommended for transfer to seawater culture.

• 한국수산과학회지
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• 제57권4호
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• pp.355-363
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• 2024

Although aquaculture shrimp production has increased, disease mortality has also increased. Acute hepatopancreatic necrosis disease (AHPND) is an emerging disease that significantly reduces production. In this study, we have investigated the potential of medicinal herbs in enhancing the immune system of shrimp. A mixture of medicinal herb extracts (Han In-jin, Artemisia iwayomogi kitamura and Cham Dang-gwi, Angelicae gigas Nakai) was absorbed into pellets and fed to whiteleg shrimp Litopenaeus vannamei for 12 weeks. The weight gain, immune activity, and disease resistance effects of the shirmp were examined. The growth performance of shrimp fed the mixture of medicinal herbal extracts was higher than that of the control group. The prophenoloxidase (proPO) activity was found to be significantly higher at 8 weeks in the 0.1% medicinal herb extract fed group. The cumulative mortality when artificially infected with AHPND pathogens commonly decreased in the 8 weeks fed group when compared with the control group. Furthermore, the RPS (relative percentage survival) was improved. This study confirmed that a mixture of medicinal herbal extracts has a positive effect on growth performance, innate immunity and disease resistance in shrimp. The optimum concentration of the medicinal herb extract for shrimp feed was 0.1% .

• 한국어병학회지
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• 제19권3호
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• pp.215-225
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• 2006

자연산어류의 질병 감염 실태를 파악하기 위하여 2006년 6월에 남해안 해역에서 트롤에 의하여 어획된 개체 중 13 종 176 개체의 어류와 1 종 15개체의 새우류 등 총 191 개체의 자연산어류에 대한 바이러스성 및 세균성 질병에 대한 모니터링을 실시하였다. 조사 결과 우리나라 양식 어류의 주요 질병과 관련한 바이러스성 병원체의 존재는 확인되지 않았다. 시료 6 개체에서 세균이 분리되어 확인한 결과 Pseudomonas속 세균 5 균주와 Proteus속 세균 1균주가 확인되었으나 양식 어류의 폐사와 관련한 세균군은 아닌 것으로 판단되며, 양식산어류의 질병 발생에 대한 관련성을 밝히기 위하여 자연산어류에 대한 더 많은 조사가 필요할 것으로 사료된다.