• Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.1-4
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• 2002

The modulatory effects of oxytetracycline treatments at high concentrations on the infection potential of scuticociliates in cultured juvenile olive flounder (Paralichthys olivaceus) and density of the ciliates in culturing water were investigated. The groups bathed with 400 and 500 ppm of oxytetracycline showed significantly lower intensities of scuticociliates on the fish and considerably lower number of the ciliates in culturing water when compared with the control group. However, the intensity of scuticociliates on the fish in the group bathed with 300 ppm of oxytetracycline was not significantly different with that of the control group in spite of considerably lower number of scuticociliates in culturing water than in that of the control group. Although the intensities of scuticociliates on the fish intubated orally with 400 and 500 mg/kg of oxytetracycline were lower than that of the control group, there were no statistical significances. In contrast, the fish fed 300 mg/kg of oxytetracycline showed significantly lower intensity of scuticociliates when compared with other groups. The results of this study suggest that oxytetracycline treatments can modulate occurrence of scuticociliatosis in fish farms probably through change of bacterial density, damaging to scuticociliatosis and immuno-suppression of fish.

• Journal of fish pathology
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• v.18 no.1
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• pp.29-37
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• 2005

This study investigated external symptoms, behavior characteristics and the distribution pattern of the scuticociliates in the skin, gill and blood vessel of the tiger puffer, Takifugu rubripes, infected with scuticociliates among tiger puffer cultured. The fish infected with scuticociliates did not show any external symptoms, such as change in body color or swimming behavior, in the early infection stage. However, they showed congestion, erosion, and ulcer on the skin and fin at advanced stages. They showed a turning movement, mainly stayed on the bottom, and swam with their mouths open at the surface of water. Some fish showed a sudden swimming movement of zigzag type. The scuticociliates were ovoid in shape and $20\times40{\mu}m$ in size. The scuticociliates had a contractile vesicle and a caudal cilium that ranged 10-12 ${\mu}m$, and reproduced by binary fission. Therefore the scuticociliates were identified as ciliated, belonging to class Hymenostomatia, order Scuticociliatida in morphogenetic character. The gills infiltrated with scuticociliates showed clubbed gill filament due to hypertrophy of gill lamella. Within the blood vessels, scuticociliates were observed one to ten individuals, depending on diameter of the blood vessels. Some of the scuticociliates were observed to have ingested erythrocytes.

• Journal of Species Research
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• v.10 no.2
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• pp.184-190
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• 2021

The diversity of scuticociliates (subclass Scuticociliatia Small, 1967) had previously been superficially investigated in Korea and only 10 species were reported according to the National Species List of Korea published in 2019. Here, we identify four scuticociliates, collected from three coastal water samples, by observing protargol-impregnated specimens. As a result, the present species belong to the order Pleuronematida Fauré-Fremiet in Corliss, 1956 and their lower taxonomic classifications are as follows: family Eurystomatellidae Miao et al., 2010 - Eurystomatella sinica Miao et al., 2010; family Pleuronematidae Kent, 1881 - Pleuronema grolierei Wang et al., 2008, P. setigerum Calkins, 1902, and Schizocalyptra aeschtae Long et al., 2007. The family Eurystomatellidae and the genus Schizocalyptra Dragesco, 1968 are reported for the first time in Korea. Considering that the scuticociliates are a species-rich group and very common in most habitats(including freshwater and terrestrial habitats), our findings indicate that we are far from understanding the complete diversity of Korean scuticociliates.

• Journal of fish pathology
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• v.31 no.2
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• pp.109-113
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• 2018

The purpose of the present study was to determine whether the scuticocidal activity of olive flounder (Paralichthys olivaceus) head-kidney leucocytes can be enhanced by stimulation with polyinosine-polycytosine [poly (I:C)]. The growth of Miamiensis avidus was not affected by exposure to unstimulated or poly (I:C)-stimulated leucocytes alone, heat-inactivated immune serum alone, or unstimulated leucocytes plus heat-inactivated immune serum. However, leucocytes stimulated with poly (I:C) showed clearly high scuticocidal activity against M. avidus in the presence of heat-inactivated immune serum. Furthermore, numerous poly (I:C)-stimulated leucocytes occupied the surface of scuticociliates in the presence of the heat-inactivated immune serum, which led to lysis of scuticociliates. These results suggest that both of the stimulation of leukocytes and the immobilization of scuticociliates are necessary to kill scuticociliates by leukocytes.

• Journal of fish pathology
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• v.18 no.1
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• pp.99-103
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• 2005

This study investigated the distribution of scuticociliates in the intestine, spleen, kidney, testis, brain, pericondrial bone and muscle layer of the tiger puffer, Takifugu rubripes, infected with scuticociliates. Scuticociliates were infiltrated in the connective tissues of the outer layer of the intestine, spleen, kidney, testis, brain, pericondrial bone and muscle layer. In brain, membranous tissue and optic lobe cortex separation were accompanied by the infection of scuticociliates. Other internal tissues and organs did not show any lesions expect for heavy deposition of hemosiderin in spleen.

• Journal of fish pathology
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• v.16 no.2
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• pp.135-138
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• 2003

The research was carried out to know the occurrence trend of scuticociliatosis and mortality of fingerlings in flounder. The diseased fish were collected from on-land rearing farms lind hatcheries of flounder in Jeju Island from January 1991 to December 2001. Occurrence of scuticociliatosis was about 10% of total occurred diseases from 1991 to 1996, but increased to 34.5% in 2001. Although monthly occurrence of scuticociliatosis was not related to season from 1999 to 2001, the highest occurrence was revealed in July and August. Mixed infections of bacteria including Vibrio sp. Edwardsiella tarda, Streptococcus sp., and Flexibacter sp. with scuticociliates were observed. Among the bacteria, Vibrio sp. was the highest frequency(40.1%), and the lowest one(10.1%) was Streptococcus sp., Mortality of fingerlings by scuticociliates was different sharply according to size of fish. Mortality of infected fingerlings below 7 cm of total length was 53.8%, while that of normal fingerling above 7 cm of total length was 13.2%. When fish were grown above 25 cm, mass mortality by scuticociliates infection was decreased markedly.

• Journal of fish pathology
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• v.23 no.3
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• pp.303-311
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• 2010

Our previous finding summarizing that larval sieving process is inevitable but triggers the outbreak of scutica-like ciliates (SLCs) in the seed production of Patinopecten yessoensis urged further study to determine best suggestable sieving interval in an agreeable range of water quality. In the mass seed production of the scallop, SLC outbreak was closely related to the larval sieving in which larvae were drained on the basis of every 3-day (5T), 5-day (3T), 7-day (2T), or 9-day (1T) from culture tanks onto a mesh screen and placed back into new water in cleaned tanks. The larval performance of growth and survival was clearly dependent on the sieving intervals. It was in order of 3T, 5T, 2T, and 1T for both of growth and survival and in reverse order for SLC infection frequency, confirming that larval sieving is necessary but damageable if it overwhelms the larval resistance. Interestingly, the larval damages by the sieving persisted to their ensuing spat life in terms of nursery growth, survival, and abnormality.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.538-539
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• 2001

자주복(Takifugu rubripes)은 높은 부가가치의 양식품종인 어류이나 이빨이 날카로워 그물을 절단하거나 서로 깨물어 상처를 입히고, 사육시에 공식현상이 타 어종에 비해 심하기 때문에 치어사육 및 양성시 2∼3회에 걸쳐 이빨을 절단하여 사육하는 양식이 까다로운 종이다. 자주복 양성 중에 스쿠티카섬모충(scuticociliates)의 감염에 대한 피해가 확인되었으며, 최근에 들어 양성중인 다른 해산어류에서도 스쿠티카섬모충의 감염이 대량폐사 원인으로 되어 있어 이들 섬모충에 관한 연구가 절실히 필요한 시점이다. (중략)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.1
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• pp.45-51
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• 2014

Scuticociliates are regarded as serious pathogens in marine aquaculture worldwide. In Korea, they cause mass-mortalities in fish such as the commercially important olive flounder Paralichthys olivaceus. In particular, mixed infections of scuticociliates with pathogenic bacteria have been commonly reported. During efforts to identify natural marine-algae derived products that possess anti-bacterial and anti-scuticociliate properties, we found that an 80% methanolic extract of the red alga Polysiphonia morrowii Harvey exhibits both anti-scuticociliate activity against Miamiensis avidus, which is a major causative agent of scuticociliatosis, and anti-bacterial activities against fish pathogenic bacteria. Activity-guided fractionation and isolation of the 80% methanolic extract of P. morrowii yielded three bromophenols, which were identified as 3-bromo-4,5-dihydroxybenzyl methyl ether (1), 3-bromo-4,5-dihydroxybenzaldehyde (2) and urceolatol (3) based on spectroscopic analyses. 3-bromo-4,5-dihydroxybenzyl methyl ether (1) showed the highest anti-bacterial and anti-scuticociliate activities, with a minimal inhibitory concentration (MIC) of $62.5{\mu}g/mL$ (against Vibrio anguillarum) and minimal lethal concentration (MLC) of 62.5 ppm (in seawater). Investigations of the anti-bacterial and anti-scuticociliate activities of seventeen bromophenol derivatives, including the three isolated natural bromophenols, showed that the existence of an electron donating group or atom with a non-covalent electron pair at $C_4$ of the 2-bromophenol structure may be important in anti-scuticociliate activity. These findings suggest that the extract and bromophenol derivatives of P. morrowii may provide useful alternatives in aquaculture anti-scuticociliate therapies.

• Journal of fish pathology
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• v.16 no.1
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• pp.13-21
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• 2003

The infection characteristics with scuticociliates at on-land rearing farms and hatcheries of flounder, Paralithys olivaceus was investigated during the year of 2001 by juvenile infection routes. When culture tanks for living food organisms such as chlorella, rotifer, and Artemia were searched, scuticocilates were detected both in live and dead rotifer, and at the dregs of culture tank bottoms at almost hatcheries. When rotifer infected with scuticocilates fed on fish larvae, lots of scuticocilate were inhabited at the bottom of fry rearing tanks. After feeding on scuticocilates-infected rotifer on fish larvae, first infection was detected at 10 days after bottom dwelling or 40 days old after hatching. By histopathological examination we confirmed the infection route of eyeball or brain contamination was that the ciliate worms digged through mouth and front part of the dosal fin cuticle, transferred into eyeball along the epithelium and muscle tissue, and reached finally into brain by the muscle and nerve tissue. The infection of internal organs was clarified into two routes. The first route was started from the infection at ventral and anal fin rays by the worms, and reached at the anus and rectum through the epithelium and muscle tissue. The second route was initiated from the infection at urinary organ and reached into the rectum epithelium cells, inner wall of intestine, abdominal cavity, pancreas, kidney, and pancreas. At seed production farms where fish larvae fed on scuticocilate-free rotifer, the worms were not detected not only at the food organisms culture tanks and juvenile rearing tanks but also larval flounder less than 7cm in total length.