• Journal of fish pathology
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• v.19 no.3
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• pp.189-195
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• 2006

A subtracted cDNA library of a marine scuticociliate, Philasterides dicentrarchii, in response to 17β-estradiol exposure was constructed using suppression subtractive hybridization (SSH). As a result of SSH, 275 clones were isolated, and among them, only glutathione peroxidase (GPX) gene was isolated as an antioxidative enzyme responding to 17β-estradiol. The semi-quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) analysis revealed that the transcription of GPX gene of P. dicentrarchii was clearly increased by exposure to 17β-estradiol. The GPX transcription was also clearly increased by exposure to xenoestrogens such as bisphenol A (BPA) and genistein.

• Journal of fish pathology
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• v.15 no.2
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• pp.93-97
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• 2002

The scuticociliate, a histophagous ciliate, is known to cause high cumulative mortalities in juvenile olive flounder Paralichthys olivaceus rearing in land-based tank facilities. This study examined effects of bath treatment of 3 chemical agents including formalin, hydrogen peroxide and sodium chloride. and freshwater against scnricociliates infected olive flounder. Although 100 ppm formalin and freshwater did not completeIy eliminale ue scuticociliates within the internal organ of fish, chemicals were effective to prevent scuticociliatosis from spreading. It confirms the efficacy of the chemical with treating the diseased fish for at least 4 consecutive days.

• Journal of fish pathology
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• v.17 no.2
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• pp.145-149
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• 2004

The definitive identification of ciliate species by morphological characteristics relies on time-consuming and laborious staining techniques. Therefore, in this study, we discriminated 3 scuticociliatosis causing species - Pseudocohnilembus persalinus, Uronema marinum and Philasterides dicentrarchi - in cultured olive flounder by multiplex PCR. The multiplex PCR based on the species-specific amplification of small subunit ribosomal RNA (SS rRNA) gene sequence enabled us to distinguish the 3 scuticociliate species in a simple and rapid manner, even in the sample containing the three species simultaneously. These data suggest that the multiplex PCR strategy would make it possible to avoid the cumbersome and time-consuming procedures of morphological analysis for the definitive identification of scuticociliates.

• Journal of fish pathology
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• v.18 no.1
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• pp.19-28
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• 2005

Scuticociliatosis has badly settled one of most damaging diseases during the seedling production process of olive flounder. Paralichthys olivaceus in Korea. We isolated a new type of Scuticociliate from flounder. The parasite metamorphoses to ciliate and cyst phases with each other by environmental changes and survive for a relatively long span. The ciliate was measured average 41.8 ${\mu}m$ in length and 21.0 ${\mu}m$ in width, and cyst was 17.0 ${\mu}m$ and 13.5 ${\mu}m$, respectively. Nutritional condition was determined as a major parameter of metamorphosing between ciliate and cyst stages. The ciliate transforms to a cyst stage because of food shortage, and the cyst returns to a ciliate stage with a favorite environmental condition and shows active growth and reproduction. The ciliate multiplied at the maximal density of $2.9 {\times} 10^5 {m\ell}^{-1}$cells in vitro cultivation at $15 ^{\circ}C$temperature using MS BHI medium and bacterial food sources. The ciliate could be proliferated at a 2.5 to $30 ^ \circ}C$ temperature range, pH 6 to 9, and 1 to 55 ppt salinity. Particularly, it survived over one week at $0 ^{\circ}C$temperature showing a high resistance against unfavorable environmental conditions. And the cyst survived for 320 days in the condition of $5 ^{\circ}C$with no feeding, but its survival period was markedly shortened in higher temperature conditions. The chemotherapeutants (formalin and hydrogen peroxide) were clarified as effective chemicals against the ciliate during in vitro trials, but the effect of therapeutants differed in proportion, depending upon the density and the bathing time of chemical compounds.

• Journal of fish pathology
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• v.19 no.2
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• pp.87-97
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• 2006

In previous study, scuticociliate P. dicentrachi was isolated from farmed flounder during the december 2004 to april 2005. Pathogenicity, mortality and infection symptom were studied using 3 cm and 5 cm groups of juvenile flounder. The ciliates were exponentially increased from bottom layer of the experimental tanks, which propagated within 2000 cells/ml (1.4 × 103 cell ㎖-1 ～ 2.5 × 103 cell ㎖-1) after 6 days of inoculation. The middle layer was maintained within 300 cells/ml. Both 3 cm and 5 cm groups were infected with ciliates, mainly 3 cm group showed high mortality during the experimental period. The death of 3 cm group was started from 5 days and showed 95.6% of mortality after 28 days of first inoculation. The control group showed 4.4% of mortality however, we could not observed any ciliates. The death of 5 cm group was started later than 3 cm group after 18 days of first inoculation. The total mortality was 71% during 28 days. No mortality and infection symptoms were observed in the control. We also studied SSU rRNA gene of ciliates which, re-isolated from infected flounder of experimental groups. When SSU rRNA in this study compared with previous data showed that the identified strain of both previous and present study was same.

• Journal of Aquaculture
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• v.19 no.3
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• pp.197-204
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• 2006

The pathogenicity and infection route of the Scuticociliate, Philasterdies dicentrarchi, were investigated with the 3 and 5 cm-group of juvenile flounders, Paralichthys olivaceus. The infection rates of 3 cm-group were 40% four days post infection (D.P.I.) and increased to be 90.1% 24 D.P.I., whereas those of 5 cm-group were 20% 8 D.P.I., 42% 16 D.P.I., and 81% 24 D.P.I. The results showed there were several infection routes to internal organs Olive flounder. The first route was started with the infection at the soft part of caudal fin and later reached at fin ray and muscle tissue; the second one was started from lips and mouth tissue of upper jaw and later the pathogen could be observed at either muscle tissue or eyeball and brain; the third one was begun at caudal fin and later the pathogen reached at brain tissu'e through spiral cord; the fourth one was started with the infections at abdominal cavity and anus. P. dicentrarchi infected to brain tissue was first observed 14 D.P.I in 3 cm-group and 20 D.P.I. in 5 cm-group of the juvenile flounder. This indicated that the brain infection of P. dicentrarchi might occur faster in small-sized flounder than large-sized one.

• Journal of fish pathology
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• v.35 no.1
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• pp.113-120
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• 2022

Scuticociliatosis caused by Miamiensis avidus is a very important parasitic disease in olive flounder farming industry. The aim of this study was to determine effect of combined treatment with blue LED (light-emitting diode) illumination and formalin on olive flounder (Paralichthys olivaceus) infected with M. avidus. Different intensity of 405 nm LED (20, 40, and 60 μmol·m^-2·s^-1) was illuminated on 2.2×10⁴ cells/well of M. avidus in a 24 well microplate for 24 h. Also, 2.4×10⁴ cells/well of M. avidus were exposed to varying combinations of 60 μmol·m^-2·s^-1 of 405 nm LED and serial 10-fold dilutions of formalin (from 10 to 100 ppm) for 15, 30, 45, and 60 min. Surviving M. avidus were counted using a hemocytometer. For in vivo test, flounder acclimatized at 11-12 practical salinity unit (psu) were challenged with 2×10⁶ cells/ml of M. avidus by immersion method for 1 h. Then, fish were moved and divided into four groups; "F" group, treated with formalin at 50 ppm; "L" group, treated with 60 μmol·m^-2·s^-1 of 405 nm LED; "C" group, treated with combination of the two methods; and the control group. After treatment for 30 min, fish were transferred to new tanks (salinity = 11-12 psu) and observed for 3 weeks. As a result, illumination of 405 nm LED at 60 μmol·m^-2·s^-1 killed 100% of M. avidus after 12 h, while 67% and 90% of the scuticociliate died at 20 and 40 μmol·m^-2·s^-1, respectively, after 24 h exposure. One hundred percent of M. avidus was killed at 90, 80, 80 and 70 ppm after exposure to formalin for 15, 30, 45 and 60 min, respectively. However, combined method (e.g., 60 μmol·m^-2·s^-1 of 405 nm-LED plus 50 ppm formalin) killed the parasite within 30 min. From in vivo test, similarly, survival rates of fish challenged with M. avidus were 100%, 43%, 29% and 0% in the C, F, L, and control groups, respectively. Results obtained in this study demonstrates that the combined treatment method has clear synergistic effect on scuticociliatosis in fish.

• 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.

• Fisheries and Aquatic Sciences
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• v.6 no.3
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• pp.155-159
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• 2003

Lipid composition and fatty acid composition were characterized in the membrane of a marine ciliate protozoan (Uronema marinum). Phospholipids accounted for 70% of total lipid, and the remainder was neutral lipids. Total phospholipids were separated as phosphatidylcholine $(24.26\%)$, phosphatidylethanolamine $(22.21\%)$, phosphatidylinositol $(6.14\%)$, phosphatidyl­serne $(5.11\%)$, cardiolipin $(3.07\%)$ and unidentified phospholipids $(28.72\%)$ through high performance liquid chromatography (HPLC). Fatty acid composition of neutral lipids and phospholipids was determined by gas chromatography (GC), based solely on comparision of retention times. In neutral lipids, the most abundant fatty acid group was monounsaturated fatty acid $(48.3\% of total fatty acids)$ with oleic acid (18:1) and nervonic acid (24:1). Saturated fatty acids comprised $29.6\%$ of total fatty acids, with palmitic acid (16:0), stearic acid (18:0) ane myristic acid (14:0), and polyunsaturated fatty acid accounted for $33.0\%$ with $Di-homo-\gamma-linolenic$ acid (20:3) and linoleic acid (18:2). Wherease phospholipids predominantly contained the fatty acid group in the following order: polyunsaturated fatty acids $(52.7\%\;of\;total\;fatty\;acids)$ with linoleic acid (18:2) and $\gamma-linolenic$ acid (18:3) > monounsaturated fatty acids $(28.5\%\;of\;total\;fatty\;acids)$ with oleic acid (18:1) and palmitoleic acid (16:1) > saturated fatty acids $(25.5\%\;of\;total\;fatty\;acids)$ with palmitic acid (16:0), stearic acid (18:0) and myristic acid (14:0).

• 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.