• Journal of fish pathology
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• v.12 no.2
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• pp.101-105
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• 1999

In a survey of net-caged yellowtail Seriola quinqueradiata in the southern parts of Korean Peninsula, we found infestations of ciliate in the gills of the moribund fish during the abnormally elevated temperature. The ciliate was very similar to genus Colpoda Muller, 1773 on morphological and reproductive characteristics. Histopathological changes revealed that the ciliate invaded gills only, causing extensive destruction of the gill filaments including lamella without any clinical signs found in the other organs and tissues. This is the first record of the parasitic ciliate in cultured yellowtail.

• Journal of fish pathology
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• v.21 no.3
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• pp.167-174
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• 2008

Few studies on parasitic scutica-like ciliates (SLCs) influencing larval growth and survival during the seed production of the Japanese scallop, Patinopecten yessoensis have been performed in spite of relatively high magnitude of their infectious damage to the larvae. In the mass seed production of the scallop, SLCs were never infectious during D-larval stage which lasted 6 to 7 days. Indeed, the infection first occurred in 2 to 4 days after first umbo-staged larvae. A regular selection of active larvae in swimming behavior kept larval SLC infection low throughout the culture compared to unselected control (P<0.05) in which all the larvae alive were contained. Higher infection frequencies of the unselected control resulted in lower larval survivals and wider range of larval size distribution that drove larval attachment rate lower. To the worse, the nursery spats from the higher SLC infection exhibited a retarded growth and elevated occurrence of abnormal scallop.

• Journal of fish pathology
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• v.22 no.1
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• pp.45-52
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• 2009

Zebrafish was firstly applied to an experimental model for scuticociliatosis caused by Philasterides dicentrarchi, a facultative parasitic ciliate in cultured marine fish. The susceptibility of zebrafish to infection of P. dicentrarchi was assessed by intraperitoneal injection of the ciliates, which produced typical symptoms of scuticociliatosis and significant mortality. The potential use of zebrafish as a model to evaluate the vaccine efficacy against scuticociliatosis was analyzed by immunization of zebrafish with the ciliates lysate. Furthermore, the effect of different adjuvants, such as Quillaja saponin (QS), Montanide, and Freund’s incomplete adjuvant (FIA) on the protective efficacy of the vaccine was investigated. Groups of zebrafish injected with QS or Montanide alone showed higher survival of fish against challenge test compared to control fish. The results suggest that adjuvant-mediated enhancement of innate immune responses play important roles in protection of fish against scuticociliatosis. The considerably high survival in the fish immunized with the antigen alone indicates that the ciliate lysate itself is highly immunogenic to zebrafish, which can elicit protective immune responses. The protective potential of the antigen, ciliate lysate, was enforced through combined administration with adjuvants including QS, Montinide and FIA. No or low mortalities in the groups of fish immunized with the antigen plus adjuvants suggests that the adaptive immune responses of zebrafish might be accelerated by the adjuvants or the protective potential of the antigen and adjuvants might synergistically interact. In spite of several shortcomings such as difficulties in sampling of serum and leucocytes enough to routine immunological analyses, zebrafsih might be the most convenient experimental animal for scuticociliatosis.

• Journal of fish pathology
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• v.9 no.2
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• pp.113-118
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• 1996

During a study to document more fully the parasitic ciliates of Korean freshwater fishes, we found numerous small ciliates in the gills and skin of crucian carp, Carassius carassius. Cursory examination indicated that the ciliate were very similar with Chilodonella sp. In this study, we described the morphometrics of this ciliate in detail and compared with other species of Chilodonella in the world. Numerous small ciliates were observed in the body surface, fins and gills of infected fish and excessive mucus production were seen in those fish. Sometimes ulcer was observed in the body of moribund fish. From the scrutinized observation of the parasite, it was identified as Chilodonella hexasticha. The parasite was dorsoventrally flattened body, without a notch in the posterior margin, and it measured 30-$45{\mu}m$ long and 15-$30{\mu}m$ wide. In number of kineties, the right band ciliature was 3-5 and the left band ciliature was 3-5. The right ventral ciliary band shaped arch and was longer than the left, straight band. It had a single oval macronucleus, 8-$15{\mu}m$ in diameter, a single micronucleus, 2-$4{\mu}m$ in diameter. The cytopharynx was reinforced by 10-16 conspicuous nematodesmata, which shaped like a tube and curved at its inner end. Two contractile vacuoles, one anteriorly at right and the second posteriorly at left were observed in wet mounts. This parasite reproduced by a simple division at $22{\pm}1^{\circ}C$.

• Journal of fish pathology
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• v.9 no.1
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• pp.21-31
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• 1996

Concerned to the Ichthyophthiriasis of aquacultural fishes, the developmental features of Ichthyophthirius multifiliis were studied in cultured Korean catfish, Silurus asotus, and rainbow trout, Oncorhynchus mykiss. In the morphological observation, the parasite developed on two kinds of parasitic and non-parasitic phases with 6 developmental stages termed phoront, trophont, protomont, tomont, tomite, and therone. The $60{\times}40-100{\times}70{\mu}m$ fusiform or spherical phoront for the invading stage has 34-38 meridional kineties and begins to develope buccal apparatus. The 80-$800{\mu}m$ spherical or amoeboid trophont for the vegetative stage has a horseshoe shape macronucleus, a inconspicuous cytostome and developmental contractile vacuoles. The 200-$800{\mu}m$ spherical protomont for the encysting stage has a inconspicuous macronucleus, abundant contractile vacuoles; and a fine gelatinous exocyst is exuded, the baccal apparatus begins to resorb. The tomont for the encysted dividing stage has a thick cyst wall, and the buccal apparatus is resorbed completely. A small 35-$50{\mu}m$ spherical tomite for each daughter cell has a cytostome end the conspicuous oral apparatus. The $25{\times}20-60{\times}40{\mu}m$ fusiform theront for the infective stage possesses a perforatorium in the anterior end, a cytostome in the mid-point respectively and has 34-38 meridional kineties. In the experiments of the reproductive, the excysted time is related to water temperature. Tomitogenesis takes 10-14 hours at $28^{\circ}C$, 12-15 hours at $26^{\circ}C$, 16-18 hours at $22^{\circ}C$, 24-28 hour at $18^{\circ}C$, 26-51 hours at $14^{\circ}C$, and 129 hours at $9^{\circ}C$ respectively.

• Journal of Aquaculture
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• v.20 no.2
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• pp.81-84
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• 2007

We studied two research items that can be undetermined issues in the artificial seed production of the Japanese scallops, Patinopecten yessoensis, batch-specific quality of the reproductive outputs and nursery acclimation, in the embayed waters of Yangyang, Gangwon, Korea. The first batch of the spawner showed better results in terms of survival, growth, and resistance against parasitic ciliate infection over the second batch that was obtained in 5 days after first batch from the same spawner. The early attached spats directly placed in the farming ground (the unacclimated) were resistant against the water current of the open environment, by showing survival of about 80% for a month, a normal survival compared with other results. However, the spat survival during the nursery acclimation was significantly lowered in comparison with that in the unacclimated condition (P<0.01). We discussed the research results of the two items, particularly focusing on their availability for mass seed production for aquaculture in the Korean coastal waters of the East Sea (Sea of Japan).

• Parasites, Hosts and Diseases
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• v.29 no.2
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• pp.129-138
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• 1991

Tetrahymena pyriformis is a free-living ciliate protozoan in the freshwater system. Experiments were carried out to determine whether intraperitoneal administration of T. pyriformis (GL strain) to mice activates macrophages to be able to kill Toxoplasma gondii tachyzoites in vitro. Mice were also injected intraperitoneally with several synthetic activators; dimethyldioctadecylammonium bromide (DDA), dextran sulfate, complete Freund's adjutant (CFA) as well as Toxoplasma and Tetrehymena Iysates in order to activate mouse peritoneal macrophages. One week after the administration of activators, peritoneal cells were harvested and the adherent macrophages were challenged with Toxoplasma tachyzoites. Macrophage monolayers were then fixed with absolute methanol after washing, and stained with Giemsa solution. The percentage of the adherent cells infected and total number of organisms per 100 macrophages were calculated to make toxoplasma-cidal activity of macrophages according to the cultivation time. Peritoneal macrophages from mice administered with Tetrahymena exhibited significant protection against target parasites as compared with those treated with synthetic activators. Among non-biological synthetic activators, DDA was evaluated as an ellcellent activator.