• Journal of fish pathology
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• v.29 no.1
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• pp.7-12
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• 2016

In a previous study on the parasites of cultured rock bream (Oplegnathus fasciatus), we reported the discovery of a new species, Ceratomyxa oplegnathus, obtained from the gallbladder. In the present study, we found another Ceratomyxa species, C. sparusaurati, also from the gallbladder of rock bream. The morphological and ultrastructural characteristics of C. sparusaurati were investigated using light and transmission electron microscopy (TEM).

• Journal of fish pathology
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• v.19 no.2
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• pp.109-117
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• 2006

A new myxosporean species Ceratomyxa oplegnathus n. sp. was found from the gallbladder of cultured rock bream, Oplegnathus fasciatus. Mature spores were 44.14 ± 2.41 (39.04-48.41) ㎛ in length, 8.52 ± 0.36 (7.9-9.26) ㎛ in width in sutural view. Spores contained two spherical polar capsules measuring 3.04 ± 0.2 (2.71-3.37) ㎛ in diameter and a binucleated sporoplasm. Each polar capsule had a 5-6 coiled polar filament, and was situated near the sutural line. In ultrastructural observation, asynchronous divisions of generative cells without pansporoblast formation gave arise to 2 spores within a trophozoite. Sporoplasmic cell in the sporoblast was binucleated, and capsulogenic cells had large amounts of rough endoplasmic reticulum, external tubules, and capsular primordia.

• Fisheries and Aquatic Sciences
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• v.13 no.1
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• pp.56-62
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• 2010

To determine whether long double-stranded RNA (dsRNA) induces RNA interference and type I interferon (IFN) responses in fish, long dsRNAs encoding enhanced green fluorescent protein (EGFP), GFPuv, and polyinosinic-polycytidylic acid sequences were co-injected with an EGFP expressing plasmid, into rock bream (Oplegnathus fasciatus). We investigated the EGFP mRNA and protein levels, and the transcriptional responses of dsRNA-dependent protein kinase and Mx1 genes. Long dsRNAs were strong inducers of a type I IFN response in rock bream, resulting in nonspecific suppression of exogenous gene expression. Furthermore, sequence-specific knockdown of exogenous gene expression at the mRNA level was detected at an early phase (24 h). These results suggested that long dsRNA may inhibit exogenous gene expression through an early mRNA interference response and a later type I IFN response in fish.

• Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.171-176
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• 2013

The aim of this study was to investigate the in vivo toxicity of di-2-ethylhexyl phthalate (DEHP), on the immune system of the rock bream, Oplegnathus fasciatus. Fish were injected twice intraperitoneally with DEHP (200, 400, and 800 mg/kg BW), and the cellularity and functional activity of phagocytes in the spleen and head kidney were measured. The number of head kidney leukocyte cells was significantly greater in fish treated with 800-mg DEHP/kg BW. Nonspecific immunity, as determined by the phagocytic index, was significantly decreased at 800-mg DEHP/kg BW in the head kidney. A significant reduction in phagocytic capacity was observed in the head kidney at ${\geq}$400-mg DEHP/kg BW. Furthermore, significantly increased levels of serum glutamic oxaloacetate transaminase and glutamic pyruvate transaminase indicated a marked hepatic dysfunction in immunosuppressed fish. Total serum protein was significantly reduced at ${\geq}$400-mg DEHP/kg BW; however, there were no significant changes in lysozyme activity. These results demonstrate that immune responses in the rock bream, Oplegnathus fasciatus can predict immunotoxicity at doses ${\geq}$400-mg DEHP/kg BW.

• Journal of fish pathology
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• v.34 no.2
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• pp.243-248
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• 2021

Offshore wind power generation is an energy generation field that is rapidly developing owing to the increasing demand for clean energy. However, the physiological response of fish to the underwater noise generated during construction or operation of wind turbines is unclear. We confirmed the effects of sound pressures of 125, 135, 145, and 155 dB/µPa, including 140 dB/µPa (the standard sound pressure for noise damage recognition in South Korea), through serum analysis in rock bream (Oplegnathus fasciatus). High mortality induced by reduced immunity through artificial infection after stimulation was confirmed. These results suggest that rock bream is negatively affected by the noise generated during the construction of offshore wind power plants.

• Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.261-265
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• 2013

The study was conducted to investigate the responses of the hepatic microsomal cytochrome P450 monooxygenase system in the rock bream Oplegnathus fasciatus after chronic exposure to 0, 1, 2, 4, and $8{\mu}g/L$ tributyltin (TBT) concentrations for 4 weeks. Hepatic cytochrome 450 content and ethoxyresorufin O-deethylation (EROD) activity were found to significantly increase in fish treated with the higher concentration of TBT (${\geq}4{\mu}g/L$); however, no significant changes were observed in penthoxyresorufin O-deethylation (PROD) activity in all treated groups compared to the control group. These findings suggest that exposure to a low TBT concentration (${\geq}4{\mu}g/L$) has the potential to induce cytochrome 450 content and EROD enzyme activity in hepatic tissue in the rock bream.

• Journal of fish pathology
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• v.23 no.3
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• pp.429-440
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• 2010

We constructed a rock bream (Oplegnathus fasciatus) gill cDNA library and a total of 1450 expressed sequence tag (EST) clones were generated. Gene annotation procedures and homology searches of the sequenced ESTs were locally done by BLASTX for amino acid similarity comparisons. Of the 1450 EST clones, 1022 EST clones showed significant homology to previously described genes while 428 ESTs were unidentified, and 259 clones were hypothetical, or unnamed proteins. Encoding 313 different sequences were identified as putative bio-defense genes or genes associated with immune response.

• Fisheries and Aquatic Sciences
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• v.12 no.1
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• pp.49-53
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• 2009

We conducted a histological analysis to investigate the influence of nutritional changes on melano-macrophages (MMs) accumulation in the kidney of sub-adult rock bream (Oplegnathus fasciatus). Four experimental groups were established (initial control, control, fed and starved), and fed commercial feed amounting to 1-3% of their body weight for 2 weeks prior to initiation of experiments. Kidney MMs with dark brown pigment were randomly observed in the kidneys of starved fish, increasing rapidly after 4 weeks, while deposition levels remained low throughout the experiment in the control and fed groups. These results suggest that catabolic tissue breakdown is a major factor contributing to the formation of pigments within MMs. Results also suggest that the degree of MMs deposition in the kidney can be used as alternative indicators in identifying starvation in wild and cultured rock bream.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.3
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• pp.240-245
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• 2017

In order to study for the growth of fish in the aquaculture industry, the behavior analysis of rock bream (Oplegnathus fasciatus) depending on the temperature and LED lights was conducted. In this study, water temperatures from 10 to 30 degrees were used. One red light (wave length: 622 nm; light power: 811 mW) and one green light (wave length: 518 nm; light power: 648 mW) were used. Behavior of the rock bream was analyzed at an average moving distance for one minutes (AMD) and a rate of movement. The mean AMD were respectively 5.3 m, 7.3 m and 3.0 m in the red LED light, green LED light and control condition. The mean rates of movement were 77%, 88% and 61% respectively in the red LED light, green LED light and control condition. The mean AMD during 24 hours were 3.1 m, 3.1 m and 3.3 m respectively in the red LED light, green LED light and control condition.

• Journal of fish pathology
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• v.34 no.1
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• pp.9-15
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• 2021

Rock bream (Oplegnathus fasciatus) is a highly valued aquaculture species in Korea. However, the aquaculture industry suffers huge economic losses due to rock bream iridovirus (RBIV) infection in summer. The objective of this study was to determine genetic diversity and relationships of DNAs isolated from two groups of rock bream after RBIV infection using five microsatellite (MS) markers. The first group of fish died early and the second group of fish died later after RBIV infection. In this experiment, 90 fish (5.1±1.0 cm and 4.1±1.3 g) were injected with 50 μl of RBIV (10⁴ TCID⁵⁰/ml) and maintained at 26℃ for 15 days. Genomic DNAs were extracted from fins of 20 fish that died earlier or later after RBIV infection. These DNAs were subjected to genotyping using five MS markers (CA-03, CA3-05, CA3-06, CA-10, and CA3-36). Of these markers, CA3-05 (early death group), CA3-06 (late death group), and CA3-36 (both early and late death groups) showed different alleles distribution rates. In-depth studies are needed to provide valuable information for selecting RBIV-resistant fish. In conclusion, microsatellite marker distribution pattern differences between early- and late- death groups of rock bream after RBIV infection showing different RBIV susceptibilities were determined using MS markers and genotyping. Results of this study suggest that MS markers could be used to facilitate the selection of RBIV resistant rock bream.