• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.344-353
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• 2021

Juvenile olive flounder, Paralichthys olivaceus (mean weight 66.7±7.1 g; mean length 19.2±0.9 cm) in a bio-floc environment were exposed to microplastic (PE: polyethylene, size 40-48 ㎛) at 0, 4, 20, 100, 500 and 2,500 mg L^-1 for 96 hours. No P. olivaceus deaths were observed following microplastic exposure. In the plasma components, calcium was significantly decreased whereas there was no significant change with magnesium following microplastic exposure. Glucose was significantly decreased with over 100mg L^-1 at 48 hours and 20mg L^-1 at 96 hours. Cholesterol was significantly decreased with over 20mg L^-1 after 48 hours, whereas there was no significant change in the total protein content. In enzymatic plasma components, the AST(Aspartate aminotransferase) was significant decreased by microplastic exposure. The results of this study indicate that acute exposure to microplastic induces blood physiological changes in P. olivaceus.

• The Korean Journal of Food And Nutrition
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• v.34 no.2
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• pp.217-223
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• 2021

Vegetable oils are a rich source of bioactive substances. Phytosterols in those have been known for many years for their properties for reducing blood cholesterol levels, as well as their other beneficial health effects. Phytosterols are triterpenes that are important structural components of plant cell membranes just as cholesterol does in animal cell membranes. The aim of this study was to provide consumers with information about phytosterol contents in vegetable oils in Korea market. The contents of major phytosterols (campesterol, stigmasterol, β-sitosterol) in 50 vegetable oils of 10 kinds (perilla oil, peanut oil, avocado oil, olive oil, pine nut oil, sesame oil, canola oil, coconut oil, grape seed oil, and sunflower oil) were analyzed by gas chromatography with flame ionization detector. The average contents of vegetable oils containing 5 or more samples were in the order of sesame oil (334.43 mg/100 g), perilla oil (262.16 mg/100 g), grape seed oil (183.71 mg/100 g), and olive oil (68.68 mg/100 g). Phytosterol content of sesame oil and perilla oil was high among vegetable oils.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.2
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• pp.141-148
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• 2019

This study examined the effect of insulin-like growth factor (IGF)-I expression in the liver and muscle on the growth of Paralichthys olivaceus fed diets low in fish meal. A feeding experiment was conducted at Jeju National University, Jeju Island, Korea. Groups of P. olivaceus (total initial weight: 200 g) were maintained for 20 weeks on one of five experimental diets containing different proportions of fish meal. Diets containing 0%, 20%, 30%, 40%, and 50% fish meal were labeled FM0, FM20, FM30, FM40, and FM50, respectively. Fish growth was observed every 4 weeks during the feeding experiment, and plasma and liver and muscle tissues were sampled. Plasma IGF-I levels were analyzed using an ELISA kit. The mechanism of IGF-I receptor signaling was examined using immunoblotting and reverse transcription-polymerase chain reaction. The greatest total weight increase was observed in the FM30 group. In parallel, plasma levels of IGF-I and IGF-binding protein were highest in the FM30 group, and mRNA and protein expression were also significantly higher in this group. The first step in the IGF-I signaling pathway, tyrosine-phosphorylation checking, occurred smoothly until 20 weeks. These results suggest that a dietary ratio of 30% fish meal best promotes growth in this species. The IGF-I signaling pathway in the liver and muscle is associated with growth in P. olivaceus.

• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.259-265
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• 2021

A diagnostic test for viral hemorrhagic septicemia virus (VHSV), which infects more than 80 species of freshwater and marine fish at home and abroad, causing mass mortality, was conducted to provide quantitative data on the amount of virus expression in various tissues of flounder in chronological order. The tissues were collected in chronological order after the intraperitoneal injection of 3.0E+07 tissue culture infective dose₅₀ (TCID₅₀) per 0.1mL per fish of VHSV to randomly selected flounder. As a result of relative quantification through real-time PCR, the highest levels of virus expression were found in the spleen, kidney, gill, and liver on day 5. This study proved that the spleen was an appropriate site for the final diagnosis of VHSV in the early stages of infection and will provide important information for the diagnosis of legal infectious diseases in Korea.

• Journal of fish pathology
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• v.33 no.2
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• pp.119-125
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• 2020

During the period from 2003 to 2020, a total of 470 Streptococcus species were isolated from farmed flounder in Jeju. Out of 470 isolates, 92 (19.6%) isolates and 378 isolates (80.4%) were identified as Streptococcus iniae and S. parauberis, respectively by multiplex PCR assay. During that period, the percentage of S. iniae decreased from 56.9% in 2003 to 0.0% in 2020 whereas that of S. parauberis increased from 43.1% in 2003 to 100% in 2020. In the PCR assay for serotyping, the isolated S. parauberis showed 3 subserotypes, Ia (34.9%), Ib/Ic (46.3%) and II (18.8%). In 2003 and 2004, serotype II was dominant at 59.1% and 50.0% of isolation rates, however between 2005 and 2009, subserotype Ib/Ic was dominant (57.6%, 86.0%, 84.6%, 57.9%, and 83.3%). After 2010, except for 2015, subserotype Ia was the most dominant one. In the last 3 years (2018 to 2020), subserotype Ia was most abundant (70%), followed by subserotype Ib/Ic (16-30%). Serotype II was not isolated in 2018, but in 2019 and 2020, it showed an increased tendency to 3.4% and 16.7%, respectively. It is believed that continuous monitoring is necessary for research on counter-measures against streptococcosis of flounder.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.205-212
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• 2022

Transport is essential in the farming process of farmed fish and is one of the physical stress factors such as sorting. The effect of water temperature and anesthesia during low salinity transport was confirmed. In the experimental group, the water temperature was set to 20℃ (natural water temperature, NWT), 15℃ (cooling water temperature, CWT) respectively, in water with a salinity concentration of 35‰, 15‰ and an anesthetic (anesthesia, Anes., Sigma USA) was diluted and mixed to 50 ppm. A styrofoam box (66×42×20 cm) was used as a transport container, and 8 flounder were accommodated and transported in a plastic bag injected with 3 ℓ of seawater and liquid oxygen. As a result of the study, the concentration of cortisol before transport increased significantly from 2.4±0.1 ng ml^-1 in the experimental groups except for the CWT+35‰ group (16.7±12.8 ng ml-1). The K⁺ concentration slightly increased from 3.1±0.0 mEq l^-1 before transport to 4.5±1.1 mEq l^-1 in the NWT+15‰ group, showing no difference, and significantly increased in all other experimental groups. There was no effect on changes in blood characteristics, and water temperature and anesthetic had a negative effect on osmotic control due to stress. AST and ALT were not affected.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.6
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• pp.777-790
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• 2022

This study was conducted to investigate the nutritional characteristics of the following Korean-distributed fish species commonly consumed as sliced raw fish (CC-SRF): olive flounder Paralichthys olivaceus (OF), red sea bream Pagrus major (RS), Atlantic salmon (AS), coho salmon (CS) and sockeye salmon (SS). The crude protein and lipid contents of OF, RS, AS, CS and SS were 20.2% and 5.5%, 21.2% and 6.8%, 17.7% and 18.5%, 18.3% and 16.1%, and 20.4% and 5.7%, respectively. Regardless of the type and weight of fish species, the major amino acids were leucine, lysine, aspartic acid, and glutamic acid, whereas histidine was identified as a limiting amino acid. The major minerals in all CC-SRF were P, K and Se based on the recommended daily intake or sufficient intake for Korean males aged between 19-49 years. Among the different types of all CC-SRF, the intake of OF and SS lipids is predicted to be associated with a lower n-6/n-3 fatty acid ratio, whereas among the free amino acids, which are expected to have health functionality, we identified taurine in OF and RS, and anserine in salmons. The digestibility of OF, RS, AS, CS and SS were 60.7%, 54.9%, 48.5%, 49.6%, and 53.4%, respectively.

• Journal of fish pathology
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• v.36 no.2
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• pp.337-348
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• 2023

This study was undertaken to evaluate the effect of amprolium hydrochloride on detoxification process of olive flounder Paralichthys olivaceus. A series of two experiment was performed based on the LD₅₀ value obtained for amprolium. First, thirty flounder (average weight 230.27 g; average length 27.99 cm) was randomly allocated into five groups. Treatment was carried out using intra-muscular injection of amprolium at the dose levels of 4, 8, 16, and 32 mg/kg body weight. At 8, 24 and 48 h post injection, liver and kidney were collected for expression assay of drug metabolizing enzymes and pro-inflammatory cytokine genes. We found that the interleukin-1β (IL-1β) mRNA level were induced at 32 mg/kg and CYP1A genes showed the opposite pattern, while UDP-glucuronosyl-transferase (UGT1A7) and GST were significantly reduced in the liver. Moreover, the suppression of drug metabolizing enzymes and cytokine gene in the kidney was observed after treatment. Another treatment was carried out using intramuscular injection with 4, 8, 16, and 32 mg/kg and 60, 80, 100, 120 mg/kg body weight. At 6 days post injection, liver was collected. The IL-1β expression was markedly induced in the experimental group treated with 4 mg/kg. In addition, glutathione S-transferase (GST) mRNA level was higher in the group with 4 mg/kg. In conclusion, our data suggests that amprolium seem to cause direct or indirect physical, or biological toxicity of flounders, although this drug is considered one of the safest synthetic anticoccidial drugs of the livestock industry.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1925-1931
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• 2024

The study conducted in the northwest region of Jordan aimed to assess the levels of natural radioactivity in soil and olive mill pomace (OMP) samples. The researchers used Nal (TI) gamma-ray spectrometry to measure the activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs in the samples. The average activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs in the soil samples were found to be 18.624 ± 5.82, 12.276 ± 5.728, 518.33 ± 212.57, and 0.140 ± 0.09 (Bq, kg^-1), respectively. In the OMP samples, the average activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were 7.272 ± 4.386, 3.454 ± 1.503, and 169.997 ± 81.873 (Bq kg^-1), respectively, and no ¹³⁷Cs was detected. The study also investigated fundamental parameters associated with radon, specifically the radon emanation coefficient (Rn_EC) and radon mass exhalation rate (E_x). The Rn_EC values ranged from 0.621 to 0.78 (Bq kg^-1), with an average value of 0.71 ± 0.06 (Bq kg^-1). The estimated E_x from the soil samples ranged from 65.83 to 124.86 (mBq kg^-1h^-1), with an average value of 99.74 ± 21.73 (mBq kg^-1h^-1). Regarding radiological hazards, the study examined various parameters, including radium equivalent activity, external and internal hazard indices, gamma and alpha indices, absorbed gamma dose rate, and excess lifetime cancer risk. All of these assessed values were found to be below the worldwide recommended limits for radiological safety. Additionally, the study analyzed the concentrations of gross alpha and gross beta radioactivities in soil and OMP samples. The soil samples had an average gross alpha activity of 4.642 ± 1.04 (Bq kg^-1) and an average gross beta activity of 48.13 ± 14.50 (Bq kg^-1). The OMP samples showed an average gross alpha activity of 0.32 ± 0.27 (Bq kg^-1) and an average gross beta activity of 59.19 ± 12.94 (Bq kg^-1). Overall, the obtained results are crucial for evaluating the radiological risks associated with natural radioactivity in the northwest region of Jordan. The findings establish baseline data for comparison and reference for radioactivity levels in the environment.