• Journal of fish pathology
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• v.32 no.2
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• pp.49-57
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• 2019

In this study, we collected 39 megalocytiviruses isolated from diseased fish in Korea from 2012 to 2018. Major capsid protein (MCP) gene, a part of vascular endothelial growth factor (VEGF) gene and histidine triad motif-like protein (HIT) genes of Megalocytivirus were targeted for PCR amplification and analysis of those DNA nucleotide sequences. Korean strains revealed two genotypes (red sea bream iridovirus and turbot reddish body iridovirus types) based on the phylogeny of MCP gene. The red sea bream iridovirus type (RSIV-type) megalocytiviruses were divided into RSIV-subgroup 1 and 2. From the phylogenetic analysis of the VEGF genes, a genotypic variant of RSIV-type Megalocytivirus was identified. The HIT-like protein gene was detected in RSIVs, but not in TBRIV and ISKNV, suggesting that HIT-like protein gene may be specific in RSIV.

• Korean journal of food and cookery science
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• v.16 no.4
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• pp.352-357
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• 2000

This study was conducted to investigate the effect of the lipid and collagen content and drip volume on the hardness of fish meat. Red sea bream (cultured and wild) and flounder (cultured, cultured with obosan and wild) were used for this study. Textural differences between cultured and wild meats were determined by the measurements of hardness, lipid and collagen content, and drip volume. Lipid content of the dorsal muscle was higher especially in cultured red sea bream (3.32%) than in wild one. Cultured and wild flounder contained lower content of lipid than red sea bream. The content of collagen was higher in cultured flounder fed with obosan (8.37 mg/g muscle) and wild flounder (8.02 mg/g muscle) than others. Drip volume was the highest in cultured flounder fed with obosan (8.67%). The hardness of raw meat was correlated with the contents of lipid (r= -0.7063) and collagen (r= 0.8307), significantly. Cultured fish contained more lipid and less collagen than wild one. So, the hardness of these fish meats was lower than wild one. However, cultured flounder fed with obosan showed no difference in hardness compared with wild one. In the cooked meat, there was no relationship between the hardness of fish meat and the contents of lipid and collagen. But, the drip volume was significantly related with the hardness (r= 0.6870). From these results, the factors contributing the textural difference between wild and cultured fish meat would be the lipid and collagen contents, and two ways to improve the texture of cultured fish meat could be suggested. One is to lower the lipid content by feed control, and the other is to raise the collagen content by inducing more fish movement.

• Korean journal of food and cookery science
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• v.17 no.5
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• pp.517-522
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• 2001

Changes of nucleotides and their related compounds in raw, cooked and frozen fish muscle were studied with HPLC. Red sea bream(cultured and wild) and flounder(cultured, cultured with Obosan(equation omitted) and wild) were used for this study. In nucleotides, contents of ATP was similar to that of IMP and some of H$\times$R(inosine) and H$\times$(hypoxanthine) were existed in fresh muscle. ATP was decomposed rapidly and contents of IMP became different between cultured and wild fish after 6 hours. The content of IMP was lower in the cultured red sea bream(3.39$\mu$ mole/g) and flounder(3.17$\mu$ mole/g) than in the wi1d red sea bream(7.31$\mu$ mole/g) and flounder(5.03$\mu$ mole/g). But, the flounder cultured with Obosan contained the largest amounts of IMP After 24 hours, K values of cultured fish muscle(27.7%, 28.2%) were higher than that of wild ones(22.8%, 24.3%). The K value of cultured flounder fed with 0.3% Obosan(equation omitted)(25.7%) was between cultured and wild flounder. IMP was the one which existed the most in cooked and frozen muscle. Amounts of H$\times$R and H$\times$ were more in cooked and frozen muscle. than in raw muscle. From these results, we could suggest that the wild one was more palatable and fresher than the cultured one and the palatability of cultured one seemed to be improved depanding on the feed.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.2
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• pp.331-336
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• 2012

Red tide is a temporary natural phenomenon involving harmful algal blooms (HABs) in company with a changing sea color from normal to red or reddish brown, and which has a bad influence on coast environments and sea ecosystems. The HABs have inflicted massive mortality on fin fish and shellfish, damaging the economies of fisheries for almost every year from 1990 in South Korea. There have been many studies on red tide due to increasing damage from red tide on fishing and aquaculture industry. However, internal study of automatic red tide image classification is not enough. Especially, extraction of matching center features for recognizing algae image object is difficult because over 200 species of algae in the world have a different size and features. Previously studies used a few type of red tide algae for image classification. In this paper, we proposed the red tide image recognition method using NMF and revison of rotation angle for enhancing of recognition of red tide algae image.

• The KIPS Transactions:PartB
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• v.18B no.5
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• pp.291-294
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• 2011

Red tide is a temporary natural phenomenon to change sea color by harmful algal blooms, which finfish and shellfish die en masse. There have been many studies on red tide due to increasing of harmful algae damage of fisheries in Korea. Particularly, red tide damage can be minimized by means of prediction of red tide blooms. However, the most of red tide research in Korea has been focused only classification of red tide which it is not enough for predicting red tide blooms. In this paper, we proposed the red tide blooms prediction method using fuzzy reasoning.

• 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.

• Proceedings of the KSRS Conference
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• v.1
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• pp.495-498
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• 2006

Optical profile and spectral absorption of suspended solids in waters of Sanya bay was measured on August 8-14, 2003. Optical profile was taken by using MicroPro optical profile. Apparent optical indexes, vertical diffuse attenuation coefficient ($K_d$) and water leaving radiance (Lw), were calculated. $K_d$ at the blue end of the spectrum was greater than that at the red end of the spectrum in waters near Sanya River mouth, however, in waters near open sea, $K_d$ at the blue end of the spectrum was smaller than that at the red end of the spectrum. Distribution of water leaving radiance was relatively higher in waters near Sanya River mouth, but relatively weaker in near open sea water. Spectral absorption of suspended particulates was also measured. Results showed that the spectral absorption of chlorophyll a was greater in waters near Sanya river mouth, but relatively weaker in waters near open sea, which indicated higher concentration of phytoplankton in waters near Sanya river mouth. Except for water at the 5th sampling station, the ratio of spectral absorption of chlorophyll a to total suspended particulates in surface waters was greater than that in bottom waters at all stations.

• Korean journal of food and cookery science
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• v.17 no.6
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• pp.549-554
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• 2001

Thermal measurements were made for connective tissues of 5 different fish muscles by using a differential scanning calorimeter(DSC), and connective tissues between muscle fibers and the cross sections of muscle fibers were observed by a light microscope. Red sea bream(cultured and wild) and flounder(cultured, cultured with obosan and wild) were used in this study. It was found that the connective tissues of cultured and frozen fish muscle required less endothermic enthalpy and the endothermic peak temperature was lower than those of wild and fresh ones when they were shrunken and denatured. Therefore, it is likely that the former are more unstable to heat than the latter. The cultured flounder fed with obosan and wild flounder which contained more collagen than cultured flounder and the wild red sea bream showed clear connective tissues between fibers. The cross-section of cultured fish muscle fiber was larger than that of wild one. From these results, collagen content and thermal properties of collagen, cross section of muscle fibers seemed to contribute to the textural difference between wild and cultured fish.

• Korean Journal of Veterinary Research
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• v.48 no.2
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• pp.175-179
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• 2008

Parallux, a solid-phase fluorescence immunoassay (SPFIA) developed for detection antibiotics residue in milk, was applied for analysis of antibiotics in muscle tissue of olive flounder (Paralichthys olivaceus), rockfish (Sebastes schlegeli), and red sea bream (Pagrus major). Fishes were dipped in neomycin 140 mg/ton water, the recommended therapeutic dose, for 24 h. Muscle samples were obtained on 1st, 2nd, 3rd, 4th and 5th day after drug treatment. The concentration of neomycin in muscle was determined using an internal standard (100 ppb as neomycin). The absorbance ratio of sample to internal standard (S/C) was employed as an index to determine the muscle residues in fishes. To investigate the recovery rate, the standard solutions were added to muscle samples to give final concentrations in muscle of 0.2 and 0.5 mg/ml. The recovery rates of all spiked samples were > 85% of the spiked value. Neomycin was detected in muscles of fishes treated after the 1st day of withdrawal period. On the 2nd day after drug treatment, all muscle samples showed negative reaction (S/C ration ${\leq}$ 1.0). The present study showed that the SPFIA can be applied for predicting residues of neomycin in muscle tissues of farmed fishes.