• Fisheries and Aquatic Sciences
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• v.24 no.11
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• pp.351-359
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• 2021

The red sea bream iridovirus (RSIV) belonging to genus Megalocytivirus is responsible for red sea bream iridoviral disease (RSIVD) in marine and freshwater fishes. Although several diagnostic assays for RSIV have been developed, diagnostic sensitivity (DSe) and specificity (DSp) of real-time polymerase chain reaction (PCR) assays are not yet evaluated. In this study, we developed a TaqMan probe-based real-time PCR method and evaluated its DSe and DSp. To detect RSIV, the probe and primers were designed based on consensus sequences of the major capsid protein (MCP) genes from megalocytiviruses including RSIV, infectious spleen and kidney necrosis virus (ISKNV), and turbot reddish body iridovirus (TRBIV). The probe and primers were shown to be specific for RSIV, ISKNV, and TRBIV-types megalocytiviruses. A 95% limit of detection (LOD_95%) was determined to be 5.3 viral genome copies/µL of plasmid DNA containing the MCP gene from RSIV. The DSe and DSp of the developed real-time PCR assay for field samples (n = 112) were compared with those of conventional PCR assays and found to be 100% and 95.2%, respectively. The quantitative results for SYBR Green and TaqMan probe-based real-time PCR were not significantly different. The TaqMan probe-based real-time PCR assay for RSIV may be used as an appropriate diagnostic tool for qualitative and quantitative analysis.

• Fisheries and Aquatic Sciences
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• v.24 no.12
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• pp.428-436
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• 2021

The aim of this study was to isolate and identify secondary metabolites from Sonchus brachyotus and evaluate their antioxidant and anti-inflammatory activities. In this study, we isolated three flavonoids from a 70% EtOH extract by Medium Pressure Liquid Chromatography (MPLC) and prep-High-Performance Liquid Chromatography (HPLC). To evaluate the biological activities (antioxidant and anti-inflammatory) of these flavonoids, their in vitro inhibitory activities against lipopolysaccharide (LPS)-induced reactive oxygen species (ROS) generation, nitric oxide (NO) production, and prostaglandin E₂ (PGE₂) secretion were determined. We successfully identified three flavonoids, namely luteolin (1), luteolin-7-O-β-D-glucoside (2), and luteolin-7-O-β-D-glucuronide (3) by spectral analyses. Luteolin (1) at 20 ㎍/mL inhibited ROS generation, NO production, and PGE₂ secretion by 48.6%, 61.28% and 12.10%, respectively, and luteolin-7-O-β-D-glucoside (2) inhibited NO and PGE₂ generation by 67.03% and 20.82%, respectively. Luteolin (1) and luteolin-7-O-β-D-glucoside (2) showed similar anti-inflammatory activities; however, luteolin (1) was observed to be a stronger antioxidant. Besides antioxidant and anti-inflammatory activities, S. brachyotus extract containing luteolin (1) and luteolin-7-O-β-D-glucoside (2) is considered to possess diverse biological activities. The results indicate that S. brachyotus is an edible medicinal plant, which is believed to be significant resource of functional foods.

• Fisheries and Aquatic Sciences
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• v.25 no.5
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• pp.298-310
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• 2022

Although giant and large fish species are highly important as a keystone species in the marine ecosystem, there have been no or few studies on their spatio-temporal variations around the Korean peninsula. For this, we analyzed daily reports made by observers at 57 fishery landing sites in Korea over 6 years, from 2011 to 2016. In total, 153 fish species were re-identified based on photos and descriptions recorded by Korean observers, of which five species were classified as a giant fish over 5 m in maximum total length (MTL) and 17 species as a large fish from 3 m to 5 m MTL according to the data presented by Froese & Pauly (2021). Among the giant and large fish species, Mola mola was the most abundant species, with 75 individuals landed as by-catch. The second most abundant species was Isurus oxyrinchus (31), followed by Mobula mobular (23), Lamna ditropis (17), Masturus lanceolatus (16), Sphyrna zygaena (14), and Prionace glauca (12). As a result of cluster analysis based on the number of individuals of giant and large fish species by year and sea, six years were separated into two clusters (2011-2013 vs. 2014-2016), with high contribution of M. mola, I. oxyrinchus, and M. lanceolatus; and three seas were separated into two clusters (eastern + southern seas vs. western sea), with high contribution of M. lanceolatus, L. ditropis, and I. oxyrinchus. The largest number of M. mola accounted for 64% of the total in 2014 and 2016, and 71% in summer (June-August). It is assumed to have a correlation between seawater temperature fluctuation and the occurrence of giant and large fish species. Our study highlights importance of longterm monitoring of giant and large fish species, and can help to understand the life cycle such as natal or nursery migration of giant and large fish species around the Korean peninsula.

• Fisheries and Aquatic Sciences
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• v.25 no.6
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• pp.327-334
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• 2022

Marine resources have various biological activities and their constituents are more novel than those of land organisms. Several biologically active constituents have been found in marine organisms. Recently, many studies have reported that marine animals (MAs) can be used as functional ingredients in functional foods or nutraceutical due to their health benefits. However, no studies have extensively investigated the cosmeceutical activities of MAs extracts. Here, 70% ethanol extracts of 38 MAs were investigated for their activities of whitening and anti-aging properties for use as materials in novel cosmeceuticals. Anti-aging activities were determined by skin aging-related enzyme activities (anti-collagenase, anti-elastase, anti-hyaluronidase) and whitening activities (anti-tyrosinase, anti-3,4-dihydroxyl-L-phenylalanine [DOPA] oxidation) evaluated by colorimetric method. Among the 38 MAs, we found that Urechis unicinctus and Petrosia corticata extracts showed the strongest inhibitory effects against tyrosinase and DOPA oxidation, respectively. Our results additionally showed that Protankyra bidentata extract might provide a major source of anti-hyaluronidase and anti-elastase; meanwhile, anti-collagenase effects were similar in most MAs. Overall, these results suggest that extracts of marine animals have potential as a tyrosinase, collagenase, elastase, and hyaluronidase inhibitors. Taken together, MA resources could be considered as a novel cosmeceutical agent to be applied in cosmetic industry.

• Fisheries and Aquatic Sciences
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• v.25 no.6
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• pp.335-349
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• 2022

To optimize the hydrolysis conditions in the production of antioxidant hydrolysates from tuna cooking juice concentrate (TC) to maximize the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, TC containing 48.91% protein was hydrolyzed with Alcalase 2.4 L, and response surface methodology (RSM) was applied. The optimum hydrolysis conditions included a 2.2% (w/v) Alcalase concentration and 281 min hydrolysis time, resulting in the highest DPPH radical scavenging activity of 66.49% (0.98 µmol Trolox/mg protein). The analysis of variance for RSM showed that hydrolysis time was an important factor that significantly affected the process (p < 0.05). The effects of different drying methods (freeze drying, hot air drying, and vacuum drying) on the DPPH radical scavenging activity and amino acid (AA) profiles of TC hydrolysate (TCH) were evaluated. Vacuum-dried TCH (VD) exhibited an increase in DPPH radical scavenging activity of 81.28% (1.20 µmol Trolox/mg protein). The VD samples were further fractionated by ultrafiltration. The AA profiles and antioxidant activities in terms of the DPPH radical scavenging activity, 2,2'-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, ferric reducing antioxidant power, and ferrous ion chelating activity were investigated. Glutamic acid, glycine, arginine, and cysteine were the major AAs found in the TCH fractions. The highest DPPH radical scavenging activity was found in the VD-1 fraction (< 5 kDa). The VD-3 fraction (> 10 kDa) exhibited the highest ABTS radical scavenging activity and ferric reducing antioxidant power. The ferrous ion chelating activity was the highest in VD-1 and VD-2 (5 to 10 kDa). In conclusion, this study provided the optimal conditions to obtain high antioxidant activities through TCH production, and these conditions could provide a basis for the future application of TCH as a functional food ingredient.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.4
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• pp.287-295
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• 2022

Staphylococcus aureus (S. aureus) is known to induce apoptosis of host immune cells and impair phagocytic clearance, thereby being pivotal in the pathogenesis of atopic dermatitis (AD). Adipose-derived stem cells (ASCs) exert therapeutic effects against inflammatory and immune diseases. In the present study, we investigated whether systemic administration of ASCs restores the phagocytic activity of peripheral blood mononuclear cells (PBMCs) and decolonizes cutaneous S. aureus under AD conditions. AD was induced by injecting capsaicin into neonatal rat pups. ASCs were extracted from the subcutaneous adipose tissues of naïve rats and administered to AD rats once a week for a month. Systemic administration of ASCs ameliorated AD-like symptoms, such as dermatitis scores, serum IgE, IFN-γ⁺/IL-4⁺ cell ratio, and skin colonization by S. aureus in AD rats. Increased FasL mRNA and annexin V⁺/7-AAD⁺ cells in the PBMCs obtained from AD rats were drastically reversed when co-cultured with ASCs. In contrast, both PBMCs and CD163⁺ cells bearing fluorescent zymosan particles significantly increased in AD rats treated with ASCs. Additionally, the administration of ASCs led to an increase in the mRNA levels of antimicrobial peptides, such as cathelicidin and β-defensin, in the skin of AD rats. Our results demonstrate that systemic administration of ASCs led to decolonization of S. aureus by attenuating apoptosis of immune cells in addition to restoring phagocytic activity. This contributes to the improvement of skin conditions in AD rats. Therefore, administration of ASCs may be helpful in the treatment of patients with intractable AD.

• Fisheries and Aquatic Sciences
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• v.25 no.7
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• pp.390-402
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• 2022

In this study we investigate physical and chemical characteristics of immature and mature skipjack tuna (Katsuwonus pelamis) roes in fresh and dried forms. Fresh roes were studied for histological structure and also dried by three methods: hot air drying (HD), vacuum drying (VD) and freeze drying (FD). The obtained roe powders were analysed for proximate composition, color value, fatty acid composition, amino acid profile, equivalent umami concentration (EUC) and protein pattern. Unyolked oocytes were more common in immature roes, while fully yolked oocytes were more common in mature roes. All dried tuna roes contained high content of protein and lipid (69.31%-70.55% and 11.14%-16.02%, respectively). The powders obtained by FD provided the highest lightness value (L^*). The main fatty acid found in all roe powders was docosahexaenoic acid (DHA) (23.49%-27.02%). Glutamic acid, leucine, and aspartic acid were the three most abundant amino acids found in the powders (13.58-14.61, 8.06-8.42, and 7.81-8.39 g/100 g of protein, respectively). The mature roe powder obtained from HD provided the highest EUC value (73.09 g monosodium glutamate/100 g of samples). The protein band at molecular weight of 97 kDa (vitelline) represented the major protein. Therefore, dried tuna roe could be a functional ingredient source of protein and lipid rich in DHA and it also has potential to be used as taste enhancer with umami compound.

• Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.87-96
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• 2023

This study was designed to determine the apparent digestibility coefficients of soybean meal, soy protein concentrate (SPC), soy protein isolate (SPI), rapeseed meal (RSM), pea protein concentrate (PPC), wheat gluten meal (WGM) and wheat flour (WF) for olive flounder, Paralichthys olivaceus. A reference diet (RF) was formulated to meet the nutrient requirements of olive flounder with 1% chromic oxide (Cr₂O₃) as an inert indicator. Test diets were prepared to contain 70% RF and 30% of the test ingredient. Olive flounder, averaging 150 ± 8.0 g, was cultured in 400-L fiberglass tanks at a density of 25 fish per tank. Fecal collection columns were attached to each tank. Fecal samples were obtained from triplicate groups of fish for 4 weeks. Dry matter digestibility of SPC (75%) and WGM (76%) were significantly higher than the other test ingredients. Protein digestibility of SPC (85%), PPC (88%) and WGM (89%) were significantly higher than the other test ingredients, and protein digestibility of RSM (77%) and WF (76%) was lower than the other ingredients tested. Lipid digestibility of SPC (72%) and SPI (69%) were significantly higher than the other test ingredients. Energy digestibility of SPC (85%) and WGM (82%) were significantly higher than that of others tested ingredients. The availability of amino acids in WGM was generally higher than in other plant-feed ingredients. Therefore, SPC and WGM were seems to be efficient as potential protein sources for olive flounder compared to other tested ingredients. Overall, findings of the current study may assist in more efficient and economical formulation of diets using plant feed ingredients for olive flounder.

• Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.145-157
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• 2023

Surimi has been traditionally used as the main ingredient in gelling foods, such as imitation crab sticks. However, it can also be used to manufacture snacks without gelling properties. To assess the properties of surimi as a snack ingredient, we prepared fried fish snacks with different surimi grades of Alaska pollack (AP) and threadfin bream (TB) and evaluated their quality characteristics. AP had significantly higher protein and gel strength values than TB did. Regarding color, TB showed significantly lower lightness (L) values and higher redness (a) and yellowness (b) values than AP did, consistent with the appearance of a brown color. TB had significantly lower hardness values, higher thickness expansion, and higher oil content than AP did. Hardness was found to be positively correlated with gel strength and negatively correlated with oil content. In the micro-structure images, more blistering was formed in TB, indicating higher expansion and crispiness. In the sensory evaluation, TB showed higher overall sensory acceptance than AP did, which is the result of its high color content, crispiness, taste, and aroma. Principal component analysis of the electronic nose and tongue revealed that the samples were clearly separated. In particular, TB had more aromatic components than AP in the electronic tongue. Our findings indicate that gel strength, which determines the quality properties of surimi, does not need to be considered in snack manufacturing. In fact, surimi with low gel strength is a more suitable ingredient for snack manufacturing.

• Fisheries and Aquatic Sciences
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• v.25 no.11
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• pp.537-548
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• 2022

Apparent digestibility coefficients (ADCs) of dry matter, crude protein, crude lipid, nitrogen-free extract, energy and essential amino acids in animal-based feed ingredients were determined for olive flounder (Paralichthys olivaceus). A reference diet (RF) was formulated to contain 1.0% chromic oxide (Cr₂O₃) as an inert indicator. Nine test diets were formulated to contain RF and one of the feed ingredients (pollock meal [PM], jack mackerel meal [JMM], anchovy meal [AM], cod meal [CM], sardine meal [SM], sand eel meal [SEM], tuna meal [TM], meat meal [MM] and squid liver meal [SLM]) at a 7:3 ratio in each diet designated as PM, JMM, AM, CM, SM, SEM, TM, MM and SLM, respectively. Olive flounder, averaging 150 ± 8.0 g, were stocked at a density of 25 fish per tank in 400-L fiberglass tanks attached with fecal collection columns. Feces were collected from triplicate groups of fish one time a day for four weeks. Dry matter and crude protein ADCs of CM and SEM were significantly higher than the other tested ingredients. Lipid ADCs of JMM, CM and SEM were significantly higher than the other test ingredients. Energy ADCs of CM and SEM were significantly higher than that of the other tested ingredients. The availability of amino acids in CM was generally higher than the other animal protein sources. PM exhibited the lowest amino acid availability among the treatments. Interestingly, MM exhibited significantly higher nutrient digestibility than several marine-based ingredients. However, CM and SEM are seeming to be highly digestible and effective to use in olive flounder diet compared to the other tested ingredients. Overall, the results of this study provide information about the bioavailability of nutrients and energy in animal feedstuffs to apply when formulating cost-effective practical feeds for olive flounder.