• Journal of fish pathology
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• v.10 no.2
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• pp.153-164
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• 1997

Characteristics and pathogenicity of Yersinia sp. strain isolated from diseased cultured olive flounder, Paralichthys olivaceous were studied. The causative organisms were identified as Yersinia sp. by biochemical and biophysical characteristics. The strain was named KF-1, and it showed the optimal growth rate at pH 9.0 and 1% NaCl. Total cell protein peptide bands of the Yersinia sp. KF-1 were between 14.4-100.6 Kd in molecular weight by the electrophoretic analysis, and a total of 28 bands appeared. The band found at 32.8 Kd in molecular weight was the major one of electrophoretic phase. In the pathogenicity test of the isolate to the flounder injecting with $1.0{\times}10^7$ cfu/fish 9 died out of 10 within 60 hrs, and in the group with $1.0{\times}10^7$ cfu/fish 5 died within 60 hrs. Thus the $LD_{50}$ was presumed to be $1.0{\times}10^7$ cfu/fish. In the drug sensitivity test KF-1 strain was sensitive to chloramphenicol, gentamycin, kanamycin, streptomycin and pefloxacin, and intermediate to erythromycin, and resistant to ampicillin, cephalothin, sulfamethoxazole/trimethoprim, tetracycline and vancomycin.

• Journal of Marine Life Science
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• v.5 no.1
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• pp.1-8
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• 2020

This review is about current Streptococcosis of cultured olive flounder, Paralichthys olivaceus, in South Korea. The main bacterial species are Streptococcus iniae, S. parauberis and Lactococcus garvieae. The occurrence trend has been arranged with published data and seed bank (NIFS) data that was examined with deposited strains and the number from 2002 to 2017. S. iniae and L. garvieae were collected until 2012 and 2002, respectively, but not collected any more after that year. In recent years, the dominant strain of Streptococcosis of cultured olive flounder is S. parauberis. The phenotypic and genetic characteristics of standard strains and isolated strains were examined with published paper. Notably, we describe about distinguishing gross signs and histological signs of 3 types of Streptococcosis in this report. White turbidity of eye, hemorrhage, enteritis and ascites are main signs of S. iniae infection. Darkness of body surface, hemorrhage in somatic muscle and pericarditis are predominant in occasion S. parauberis infection. In occasion of L. garvieae infection, common signs of Streptococcosis are revealed, but these are weak tendency compared with the previous two cases.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.171-179
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• 2022

The present study investigated the survival rate, respiration rate, plasma stress index, and histological changes according to exposure time of cultured red seabream (Pagrus major) and olive flounder (Paralichthys olivaceus) exposed to Cochlodinium polykrikoides red tide. Fish cultured in natural seawater were used as the control group. Cochlodinium polykrikoides density was set to 5,500±200 cells·ml^-1 in the experimental groups. All red seabreams died within 1 hour of exposure to red tide, whereas all olive flounders died within 5 hours of exposure. Analysis of physiological response revealed that in red seabream, plasma glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), catalase (CAT), and glutathione peroxidase (GPx) concentrations were increased; plasma glucose and superoxide dismutase (SOD) concentration were decreased. Meanwhile, in olive flounders, plasma cortisol, GOT, and GPT concentrations were increased; plasma glucose concentrations were increased during the first hour of exposure, followed by decrease after 5 hours; and plasma SOD, CAT, and GPx concentrations decreased during the first hour of exposure. Histological analysis revealed structural damage to the gills of both red seabream and olive flounder. In conclusion, the exposure of red seabream and olive flounder to Cochlodinium polykrikoides red tide at the density of 5,500 cells·ml^-1 induces oxidative stress, which activates antioxidant defense mechanisms, ultimately leading to liver and gill damage.

• Journal of fish pathology
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• v.24 no.1
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• pp.1-9
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• 2011

Viral haemorrhagic septicaemia virus (VHSV) is an epidemic virus in olive flounder Paralichthys olivaceus farms in Korea, since the virus have first isolated in 2001. In the present study, partial glycoprotein (G) gene nucleotide sequences of seven Korean VHSV from cultured olive flounder and wild marine fishes in coastal areas of Korea were analyzed to evaluate their genetic relatedness to worldwide isolates. Phylogenetically, all Korean VHSV formed only one minor cluster including Japanese isolates, in genotype IVa, while the North America isolates formed a different minor cluster in genotype IVa. These results suggest that Korean VHSV could be an indigenous virus in Korean and Japanese coastal areas, but have not been introduced from North America.

• Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.123-129
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• 2011

To determine whether rearing density affects the hypermelanosis on the blind side (ambicoloration) of olive flounders Paralichthys olivaceus, we reared fry with an unpigmented non-eyed (blind) side in duplicate at densities of 150 individuals/$m^2$ (commercial production density: control) and 450 individuals/$m^2$ (high density group) for 90 days in 1-t dark-green fiberglass reinforced plastics (FRP) tank. We recorded feed intake, feed conversion efficiency (FE), growth and survival, and measured the ratios of staining blind-side area (staining area) and ambicolored fish every 30 days. Daily feed intake (DFI), feed conversion efficiency (FE), growth rate, condition factors, and survival rate were calculated at the end of the experiment. Although the FE was higher in the high-density compared to the control, the two density groups showed similar feed intakes, growth, and survival. The ratio of staining area as well as the ratio of ambicolored fish significantly were significantly higher in the high-density group than in the control from days 30 to 60, but significantly increased and evened out by the end of the experiment (P<0.05). In conclusion, we determined that rearing density is not the main cause of the blind-side hypermelanosis, but found that increasing the rearing density can accelerate the ambicoloration in olive flounders.

• Journal of fish pathology
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• v.16 no.1
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• pp.1-12
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• 2003

RT-PCR method was applied to detect and clone the nucleocapsid protein (N) gene and glycoprotein (G) gene for sequencing 5 Korean VHSV isolates from cultured olive flounder, Paralichthys olivaceus. Phylogenetic analysis was performed to investigate their relationship with the VHSV strains described previously and isolated from different geographical area. Generally, VHSV strains were separated phylogenetically according to the major geographical area of isolation: Genogroup I (American type), Genogroup Il (British Isles) and Genogroup ill (European type). This study revealed that all 5 Korean VHSV isolates were belonged to Genogroup I and closely related to Japanese Obama25 type.

• Journal of fish pathology
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• v.21 no.3
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• pp.271-278
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• 2008

The epidemiological study was performed to survey the prevalence of 5 bacterial, 6 viral and 5 parasitic disease of cultured olive flounder, Paralichthys olivaceus in Pohang, Ulsan∙Gijang, Keoje and Wando area of Korea from February to December, 2007. The disease frequency of size groups were as follows; Among the 1,218 fish samples, less than 10 cm (67.6%), 11~20 cm (70.2%), 21~30 cm (73.4%), 31~40 cm (77.6%), above 41 cm (88.2%). The highest detection rates of pathogens were recorded in samples from August and Ulsan. The detection rates of parasites, bacteria or viruses were 43.2%, 38.8% and 24.4%, respectively. The distribution of specific diseases showed that detection rates of diseases occurring the most frequently during the study period were Trichodina (33.1%), viral nervous necrosis virus (16.0%), Vibrio (9.7%), Scutica (10.1%), Ichthyobodo (5.7%).

• Fisheries and Aquatic Sciences
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• v.21 no.6
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• pp.17.1-17.7
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• 2018

This study investigated the trend in emaciation infection outbreak in olive flounder (Paralichthys olivaceus) of Jeju island, South Korea, during 2014-2015. A total of 900 fish were systematically examined by PCR method using the EM-F/EM-R primer set in April, May, September, November, and December 2014, and the infection rate was recorded. In 2015, the same examination was conducted in March, May, July, and October but with 660 fish. It was found that the infection rate was 18.3~71.6% in 2014, which increased to 16.3~90.3% in 2015. Furthermore, September and December in 2014 and March, July, and October in 2015 showed a relatively higher infection rate. According to the infection trend analysis, which depended on the sample size, the infection occurred in all of fish sizes in this study and 11~30 cm fish group showed the highest infection rate. Histological examination confirmed that the kidney areas of the emaciating infected olive flounder contained several spores of $4{\sim}9{\mu}m$, and in severe cases, the elimination and destruction of tissue were confirmed by PCR. Thus, an important portion of farmed olive flounders in the Jeju region suffers from emaciation disease. This epidemiological survey serves as a useful reference on the emaciation disease of cultured olive flounders in Jeju

• Journal of fish pathology
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• v.34 no.1
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• pp.31-38
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• 2021

The objective of this study was to determine comparative biochemical characteristics and RAPD (random amplified polymorphic DNA) profiles of 18 strains of Edwardsiella tarda isolated from cultured olive flounder (Paralichthys olivaceus) and eel (Anguilla spp) that showed diseases between 1996 and 2010 in Korea. In terms of biochemical properties, they showed four patterns with differences in citrate degradation and production of H₂S and indole. All strains were identified as E. tarda. Characteristics of isolates were not classified according to their host. As a result of PCR with E. tarda-specific primer, EDtT, the same band of about 270 bp was detected in all 18 isolates. However, no specific band was detected in type strains of E. tarda or Edwardsiella ictaluri. As a result of RAPD PCR performed with primer No. 5 and No. 6 of a Ready-To-Go-RAPD kit, the band profile showed clear differences among isolates of olive flounder, isolates of eel, and E. tarda and E. ictaluri type strains. It was possible to organize their characteristics according to the origin of host with possibility to develop tools for pathogen monitoring.

• Journal of fish pathology
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• v.35 no.1
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• pp.47-56
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• 2022

Lincomycin as one of the lincosamides antibiotics have been mainly used in human and livestock fields, but have not been used in aquaculture. In this study, the distribution of minimum inhibitory concentration (MIC) values against lincomycin and the detection of the macrolide-lincosamide-streptogramin (MLS) resistance gene were confirmed in bacterial pathogens isolated from cultured olive flounder (Paralichthys olivaceus). Of the 107 strains isolated from Jeju, 36 strains of Gram-positive bacteria and 71 strains of Gram-negative bacteria were identified. Most of Streptococcus spp. was found to have a MIC value of less than or equal to 0.5 ㎍/mL, and Edwardsiella piscicida was found to have a MIC value higher than 1,024 ㎍/mL. V. harveyi and V. alginolyticus mostly showed MIC values of 256 ㎍/mL, but V. scophthalmi displayed values of 8~64 ㎍/mL. In the detection of MLS resistance gene, erm(B) was detected in 9 strains of Streptococcus spp., and erm(A) was confirmed in one strain.