• Fisheries and Aquatic Sciences
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• v.26 no.3
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• pp.234-240
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• 2023

Enteromyxum leei has been identified as the causative agent of emaciation disease in a wide range of marine fish hosts. In this study, we aimed to determine the effect of the parasitic infection of Enteromyxum species on starry flounder that were cultured in aquaculture farms of Jeju island in Korea. As the mortality of cultured olive flounder Paralichthys olivaceus because of E. leei infection increased, some fish farms on Jeju island attempted to culture the starry flounder Platichthys stellatus, as an alternative. Myxosporeans with a developmental stage similar to E. leei were found in the intestines of cultured starry flounders. The partial 18S rDNA of myxosporeans showed 100% similarity with E. leei. To reveal the effect of E. leei infection on starry flounder, the intensity of E. leei infection measured using quantitative polymerase chain reaction, and the condition factor (CF) of fish were measured and analyzed statistically. The results showed that high-intensity E. leei infection significantly decreased the CF of the starry flounder. However, the pathogenicity of E. leei to starry flounder is low, considering its mortality and clinical signs.

• Journal of fish pathology
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• v.34 no.2
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• pp.161-168
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• 2021

Quantitative analysis of myxosporean parasites (Enteromyxum leei and Parvicapsula anisocaudata) were performed using real-time PCR on the internal organs (head kidney, body kidney, intestine, spleen, brain, liver, heart, muscle, blood, and eye) of emaciated Paralichthys olivaceus from farm-A. The highest DNA copy number of E. leei was shown in the intestine (1.3 × 10⁸ copies/mg tissue) of emaciatied P. olivaceus and DNA copy number in the other internal organs (1.3 × 10³~4.6 × 10⁵ copies/mg tissue) showed lower than in intestine. From the result of real-time PCR for P. anisocaudata, it was considered mildly infected, due to the low DNA copy numbers of the head kidney (1.3 × 10³ copies/mg tissue) and body kidney (9.1 × 10³ copies/mg tissue). In order to investigate whether myxosporean parasites can be detected in a non-invasive way, quantitative analysis of E. leei and P. anisocaudata from rearing water of three farms were performed by real-time PCR. The DNA copy number of E. leei from rearing water of farm-A and farm-B were 8 × 10⁴ and 5 × 10⁵ copies/L, respectively. However, it was not detected in farm-C. For P. anisocaudata from rearing water, farm-A, farm-B and farm-C showed 0, 2.0 × 10⁶ and 5.1 × 10⁶ copies/L, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.660-667
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• 2021

In recent years, myxosporean infection from the cultured olive flounders Paralichthys olivaceus, have been frequently observed in Jeju island, South Korea. This study aimed to compare histopathological and molecular-biological methods of examining myxosporean infection from these flounders. Samples were obtained from affected individuals exhibiting emaciation or abdominal distention and a polymerase chain reaction (PCR) indicative of Parvicapsular anisocaudata, Enteromyxum leei and Kudoa septempunctata were initiated. Histopathological examination were conducted with H&E stained tissue sections, and then in-situ hybridization (ISH) reaction were processed with selected sections using P. anisocaudata, E. leei, K. septempunctata and Scuticociliate probes. Renal and intestinal tissue degeneration were common symptoms associated with all samples. Sever glomerular and renal tubular degeneration were evident, as were intestinal epithelial desquamation and spore formation in the epithelial cells. The results of conventional PCR analysis and ISH reactions revealed differences, and we suspect that various microparasites may have been associated with the symptoms manifested.