• Journal of Aquaculture
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• v.9 no.4
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• pp.445-452
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• 1996

Endogeneous activities of ${\beta}-galactosidase$-like enzyme in various tissues from several finfishes and shellfishes were examined by histochemical analysis based on X-gal staining and by fluorimetric measurement using 4-methylumbelliferyl-${\beta}$-D-galactoside (4-MUG). Species used in this study were 3 freshwater fishes, mud loach (Misgurnus mizolepis), common carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) ; 3 marine fishes, olive flounder (Paralichthys olivaceus), stone flounder (Kareius bicoloratus) and marbled sole (Limanda yokohamae) ; and 4 shellfishes, abalone (Haliotis discus hannai), Pacific oyster (Crassoskra gigas), pearl oyster (Pinctada fucata martensii) and ark shell (Anadara broughtonii). The activities of ${\beta}-galactosidase$-like enzyme in all finfishes examined were significantly different among species, with the wide variations between tissues in a species. In general, the tissues such as kidney, intestine and liver were ones which showed the significantly higher values in 4-MUG fluorimetry and deeper staining patterns in X-gal analysis compared to other tissues. On the other hand, serum and muscle revealed the significantly lower activities than others did, regardless of species. Shellfishes were also found to have endogenous activities of ${\beta}-galactosidase$-like enzyme which were significantly varied depending on both species and organs in a species. Hepatopancreas from all shellfishes examined showed the deepest pattern in X-gal staining and also the highest value in 4-MUG analysis, while activities of ${\beta}-galactosidase$-like enzyme in adductor muscles and mantle muscles from all shellfish species in this study except Pacific oyster were negligible : Pacific oyster had the significant activity of this enzyme in muscle tissues. Putative endogenous lacZ fragment was amplified from both finfishes and shellfishes by polymerase chain reaction (PCR). The molecular size of PCR products was about 510 bp, and there was no difference in size among species examined.

• Journal of Life Science
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• v.24 no.7
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• pp.757-761
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• 2014

Olive flounder (Paralichthys olivaceus) is an important aquaculture fish species in Jeju Island, South Korea. Due to the intensification of flounder fish farming, huge amounts of chemical antibiotics are used against several fish diseases. This has many harmful side effects on fish, as well as human consumers. Hence, an alternative to chemical antibiotic agents is needed for disease control. In this study, three strains of rhizobacteria (BRH433-2, TRH415-2, and THJ609-3) were isolated from the rhizosphere of plants. Assays of their antibacterial activity against fish pathogens, such as S. iniae, S. parauberis, V. anguillarum, and E. tarda, were performed with untreated broth culture (without cell separation), supernatant, and precipitated pellets separated by centrifugation. Among these, the cell suspension prepared from the precipitated pellet showed significant antimicrobial activity when compared with that of the untreated broth culture and centrifugal supernatant. These results indicate that the three isolated rhizobacterial strains exhibit antibacterial activity. Analysis of the 16S rDNA sequences of the BRH-433-2, THJ609-3, and TRH415-2 strains showed the highest similarity to Burkholderia gladioli (99.5%), Pseudomonas baetica (97.7%), and P. koreensis and P. baetica (98.4%), respectively. We suggest that the strains hold promise in disease management of fish.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.313-318
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• 2016

Bacteria in the viable but nonculturable (VBNC) state fail to produce colonies on routine bacteriological media, but are still alive in the state of very low metabolic activity. The aim of the present study was to induce the VBNC state of the Edwardsiella tarda using sea water microcosm under starvation conditions at $10^{\circ}C$ and to investigate resuscitation of the VBNC cells in temperatures changed from 10 to $25^{\circ}C$, with and without additives. E. tarda entered into the VBNC state within about 42-84 days of incubation in the microcosm. Throughout this period, the total cell counts as determined using acridine orange direct counting remained near the original inoculum level of ${\sim}10^8cells/ml$. The live cell counts measured with direct viable counting, on the other hands, declined to ${\sim}10^4cells/ml$. When the VBNC cells were incubated with addition of yeast extract, fish muscle extract or serum at $25^{\circ}C$, the ratios of resuscitated samples were 37%, 23%, and 37%, respectively. The characteristics of resuscitated E. tarda were consistent with those of the original E. tarda. When the resuscitated E. tarda were intraperitoneally injected into olive flounders, all fishes died within 5 days, indicating that the VBNC E. tarda might retain its pathogenic potential. Therefore, E. tarda under starvation conditions in the winter enter into the VBNC state and the VBNC E. tarda cells resuscitated at summer and autumn seawater temperature are considered to be pathogen continuously to olive flounder on the southern coast of Korea.

• Journal of Veterinary Clinics
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• v.23 no.3
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• pp.236-242
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• 2006

Along with olive flounder(Paralichthys olivaceus), black rockfish(Sebastes schlegeli) is another very popular maricultured species in Korea. As there is many difficulties in handlling live fish for aquaculturist, use of suitable anesthesia for proper handling of fish is very important in the field. In this view, the effect of $AQUI-S^{\circledR}$ has analysed for its use in the field. $AQUI-S^{\circledR}$, contains 50% isoeugenol, is a new anesthics for fish and zero-withdraw time required since it was approved as a safe additives of food. In the present study, black rockfish adult exhibted sedation effect from 5 ppm at $10^{\circ}C\;and\;15^{\circ}C$, and 7.5 ppm at $20^{\circ}C$, on the other hand, anesthesia was at least required 7.5 ppm at $10^{\circ}C\;and\;15^{\circ}C$, and 10 ppm at $20^{\circ}C$. The fish was recovered from sedation and anesthesia after approximately 5 and 10 minutes, respectively. In case of black rockfish fry, sedation was recorded from 2.5 ppm at $20^{\circ}C$, and 5 ppm at $15^{\circ}C\;and\;20^{\circ}C$. The least concentraion of anesthesia was 2.5 ppm at $10^{\circ}C$, 7.5 ppm at $15^{\circ}C$, and 5 ppm at $20^{\circ}C$. The acute toxic test showed that black rockfish adult and nv showed mortality above 12.5 and 15 ppm concentration of $AQUI-S^{\circledR}$, respectivly. In sum, $AQUI-S^{\circledR}$ is considered as useful anesthetic drug for sedation and anesthesia of black rockfish, it is highly availbale to be prevented from a varity of stress.

• Journal of fish pathology
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• v.20 no.2
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• pp.99-108
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• 2007

Vibrio harveyi, one of the major causal agent of vibriosis, affects a diverse range of marine vertebrates and invertebrates over a wide geographical area. The organism is synonymous with Vibrio carchariae, which is also known as a fish pathogen. The aims of this study were to investigate the characteristics of the pathogenic non-luminous V. harveyi and the luminous V. harveyi. And V. harveyi isolates were examined the pathogenicity to the black rockfish, Sebastes schlegeli. Both strains of V. harveyi showed haemolytic activity, and the survival rate of non-luminous V. harveyi FR 2 was higher than other strains in the skin, gut mucus and fresh serum of olive flounder, Paralichthys olivaceus and black rockfish, Sebastes schlegeli, respectively. The virulence of non-luminous V. harveyi FR 2 was higher than that of luminous V. harveyi VIB 391 in the intraperitoneally infected black rockfish. In conclusion, the present study revealed that the pathogenicity of V. harveyi FR 2 isolated from marine fish was higher than that of V. harveyi VIB 391 isolated from shrimp for black rockfish. It was suggested that the pathogenicity of V. harveyi on the black rockfish was related with bacterial luminescense.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.6
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• pp.349-356
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• 2015

Trace metals concentrations in the tissue of edible marine fish (4 species), olive flounder (Paralichthys olivaceus), Korean rockfish (Sebastes schlegelii), file fish (Stephanolepis cirrhifer) and abbysal searobin (Lepidotrigla abyssalis), collected near the Yongho wharf in Busan were determined to assess the potential human health risk (HRA) of trace metals by fish consumption. Levels of Li, Cr, Ni, Cu, Zn, As, Cd, and Pb in the fish tissue were $0.005{\pm}0.009$, $0.77{\pm}0.30$, $0.29{\pm}0.34$, $0.49{\pm}0.14$, $15.96{\pm}2.52$, $10.62{\pm}4.67$, $0.001{\pm}0.002$, and $0.045{\pm}0.06mg/kgdw$ respectively. The estimated daily intakes of Cu and Zn and the estimated weekly intakes of As, Cd, and Pb from the fish collected near the Yongho wharf were 0.0032, 0.054-0.18% of PMTDI (provisional maximum tolerable daily intake) and 13, 0.0041, 0.020% of PTWI (provisional tolerable weekly intake) which were set to evaluate the food safeties by the JFCFA (The Joint FAO/WHO Expert Committee on Food Additives). Lifetime cancer risk and target hazard for local residents due to those fish consumption were found to be negligible.

• Journal of fish pathology
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• v.14 no.2
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• pp.71-80
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• 2001

The purpose of this study was to investigate the microbiological characteristics and the distributions of the bacteria causing streptococcicosis occurred in marine fish farm, Korea. Many kinds of cultures fishes suffered from the disease accompanied with typical symptoms, including darkening of the skin, exophthalmia, petechiae inside of the opercula and distended abdomen. The isolates from the diseased fishes were compared with Lactococcus garvieae by biochmical, biophysical and serological methods and polymerase chain reaction(PCR) assay. We isolated 35 strains of the geuns Streptococcus from the diseased olive flounder, Paralichthys olivaceus, yellow tail, Seriola quinqueradiata and Korean rockfish, Sebastes schlegeli. 15 strains out of the isolates were identified to L. garvieae and the others were not because of their different biochemical and biophysical charateristics. Seven strains of the isolates were agglutinated by rabbit serum raised against L. garvieae $KG^+$ phenotypic cells(ATCC49156)as a reference strain. Twenty-one strains of the isolates identified to L. garvieae since they were formed the expected band through performing PCR assay using specific primers, pLG-1(5'-CATAACAATGAGATCGC-3') and pLG-2(5'-GCACCCCGCGGTTG-3'). In the present study, it showed that L. garvieae was a dominant strain causing streptococcicosis in the tested area due to occurrence of 21 strains as L. garvieae out of all the isolates, 9 atrains as Streptococcus sp. and 5 strains as Enterococcus sp.

• Journal of Aquaculture
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• v.9 no.2
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• pp.125-132
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• 1996

A study was carried out to test sex ratio of the progeny that were induced by the artificial fertilization between normal female and gynogenetic diploid eggs and sex-reversed gynogenetic diploid male sperm. Sex reversed gynogenetic diploid males were produced successfully in gynogenetic diploid female by immersion treatment with $17{\alpha}$-methyltestosterone at the concentration of 10 pub from $13.5{\pm}0.22$ mm to $57.6{\pm}5.1$ mm in total length. In $F_1$ progeny test, matings between normal females and sex-reversed gynogenetic males were not produced all female, but matings between gynogenetic diploid females and sex-reversed gynogenetic males were produced all female populations in six out of eight groups and two lots produced $96.9\%$ and $95\%$ female. These data showed that all-female populations were produced by crossing between gynogenetic diploid female and sex reversed gynogenetic diploid male.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.4
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• pp.382-388
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• 2019

Streptococcosis caused by Streptococcus parauberis is a very important disease in farmed olive flounder Paralichthys olivaceus. For most fish pathogens, including S. parauberis, there are no analytical criteria to distinguish antibioticsusceptible strains from antibiotic-resistant strains. In this study, epidemiological cut-off ($CO_{WT}$) values were generated to classify 75 strains of S. parauberis isolated from 1999 to 2018 as wild type (WT) and non-wild type (NWT) using disc diffusion data and normalized resistance interpretation (NRI) analysis. The susceptibility of the isolates to 16 antibiotics was evaluated using CLSI guideline M42-A. The wild-type cut-off values for amoxicillin, erythromycin, oxytetracycline, and florfenicol for S. parauberis were ${\geq}35$, 31, 28, and 27 mm, respectively. The NWT ratios of S. parauberis strains to treatment with GEN, FFC, ENR, SXT, EFT, VAN, and CHL were 17% or less, indicating that these antibiotics may be used to treat streptococcosis caused by S. parauberis. For recent S. parauberis isolates, the NWT ratios for AMX, ERY, OTC and FFC are much higher than for strains isolated from 1999-2007. The $CO_{WT}$ data from this study will assist aquatic animal disease professionals in prescribing appropriate antibiotics for the treatment of streptococcosis caused by S. parauberis, which will help reduce the misuse and abuse of antibiotics in the aquaculture sector.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.465-472
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• 2001

The effects of water level reduction in rearing tank and fish transference during fish selection process on the stress response (hematological factors, cortisol, glucose, lactic acid and osmolality) of tank-reared olive flounder Paralichthys olivaceus of large (FL), small (FS) and Japanese croaker, Nibea japonica (JC) were examined in running seawater culture system. The water level of rearing unit was lowered from 33 cm to 8 cm in the course of 2 minutes in the water level reduction experiment. The fish were removed from rearing tank (12 ton) to 450 L tank in 30 seconds after capture in the fish transference experiment, In water level reduction, the hematocrit of FL was significantly increased from $14.6\%$ at beginning to $23.5\%$ after 10 hours, However, it decreased to the value of beginning after 46 hours. Plasma cortisol concentration of FL was the highest concentration (13.7 ng/mL) after 22 hours, but it decreased to 4.0 ng/mL at the end of experiment. Cortisol concentration of FS did not show any significant difference during the experiment. The cortisol concentration of JC were significantly higher at 4 hours (282.3 ng/mL) and 22 hours (350.5 ng/mL), Glucose concentration of JC was the highest (138.0 mg/dL) at 22 hours. Lactic acid concentration was not different between experimental groups. In the fish transference experiment, red blood cell of FL was increased from $1.9\times10^6\;cell/{\mu}\;L\;to\;4.2\times10^6\;cell/{\mu}L$ in 24 hours. Blood hemoglobin of JC were significantly elevated in 24 hours. At 1 hour after transference, plasma cortisol concentrations in both fish species were increased to 95.3 ng/mL in FL and 175.5 ng/mL in JC. Glucose concentration of JC was increased to 132.5 mg/dL at 1 hour, 129.5 mg/dL at 3 hours after transference.