• Journal of Aquaculture
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• v.18 no.4
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• pp.293-298
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• 2005

We examined the effects of GnRHa on expression of the gonadotropin subunit gene in the pituitary and on syn-thesis of the plasma sex steroids (testosterone and 17$\beta$-estradiol) in protandrous black porgy. Fish were injected intraperitoneally with 0.2g GnRHa/g and then both the pituitary and the plasma were sampled 0, 6, 12, 24 and 48 hours after injection. The mRNA level of the FSH subunit increased at 6 hours post-injection, while the LH mRNA levels expressed are same with or without GnRHa treatment. Also, GnRHa stimulation caused a significant increase of the plasma testosterone (T) and 17$\beta$-estradiol ($E_2$) after 24 hours. The homologies of black porgy FSH to red seabream, Pagrus majoy FSH, snakehead fish, Channa maculata FSH and striped bass, Morone saxatilis FSH were $83.3\%,\;79.2\%$ and $76.0\%$ respectively. Amino acid homology analysis using the GenBank and EMBL general searches indicated that black porgy FSH has a high homology with yellowfin seabream, Acanthopagrus latus LH ($97.7\%$ identity) and red seabream LH ($83.3\%$ identity).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.1
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• pp.18-23
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• 2001

In this paper, the several indexes represented by swimming characteristics of aquarcultured red seabream, Dchrysophrys majors in a farming water raft(10L×10W×5H) were measured by ultrasonic telemetry. The fishes tagged by pingers were tracked by the LBL method(Shin etc., 1994). The location of fishes were calculated by the hyperbolic method and the indexes were estimated by the least square method. The similarity was confirmed by the comparision between experiment and simulation on the swimming trajectory of fishes, the mean distance of individual from wall, the mean swimming speed and the mean distance between the nearest individuals. The obtained results are summerized as follows ; 1. The swimming trajectory of fishes tagged by the pingers and the swimming trajectory by the simulation for 120 minutes showed a simularity. 2. The mean swimming speed by the experiment and the simulation showed 39.2 ㎝/sec (1.4BL ㎝/sec) and 44.4 ㎝/sec (1.6BL ㎝/sec), respectively. 3. The mean swimming depth by the experiment and the simulation showed 238㎝ and 248 ㎝, respectively. 4. The mean distance of individuals from wall of the farming water raft by the experiment and the simulation showed 132 cm and 129 cm, respectively. 5. The mean distance between the nearest individuals by the experiment and the simulation showed 83 ㎝ and 61 ㎝, respectively.

• Journal of fish pathology
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• v.24 no.2
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• pp.53-64
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• 2011

In quantitative studies of clinical signs, rock bream of adults and juveniles infected with Megalocytivirus IVS-1 isolated from rock bream (Oplegnathus fasciatus) in Korea showed average $4.49{\pm}1.13$ and $4.85{\pm}1.06$ of spleen index respectively. In challenge experiments, Megalocytivirus IVS-1 induced 100% cumulative mortality in both adult and juvenile rock bream. However we found 60% cumulative mortality in juvenile red sea bream (Pagrus major) even after 30 days of injection, which contradicted with the results of other laboratories. Interestingly, IVS-1 infected red sea bream of the same juvenile size with rock bream showed lower spleen index compared to that of rock bream. In real-time PCR, there was continuous increasing of the numbers of viral copies ($2.03{\times}10^7$ copies/mg) in the spleen of juvenile rock bream infected, which were different from those in adult rock bream showing plateau level after reaching to the peak level. Moreover, enlarged cell numbers in the infected spleen were also increased continuously in the juvenile but not in adult of rock bream, even decreased after reaching to peak level. Consequently, significant differences in clinical signs: cumulative mortality. spleen index and viral copy number were found between rock bream and red sea bream, but not between adult and juvenile rock bream. Certainly quantitative expression of clinical sign as in this study may be a way to compare the progression of megalocitiviral disease more accurately in different species or physiological conditions.

• Ocean and Polar Research
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• v.26 no.3
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• pp.415-423
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• 2004

An experiment was conducted to investigate the differences of total ammonia nitrogen (TAN) excretion rates and feces production rates among the offsprings from cultured Japanese strain (JJ, mean BW; $17.1{\pm}0.1g$), intraspecific hybrid strain between cultured Japanese and selected Korean strain (JK, mean BW: $17.1{\pm}0.1g$) and selected Korean strain(KK, mean BW: $21.5{\pm}0.1g$) of red sea bream in order to compare their dietary protein utilization efficiency. Fish were hand-fed with a commercial diet containing 46.7% crude protein for 2 weeks, three times daily 09:00, 13:00 and 17:00. After daily feeding, the TAN excretion rates reached peaks of 49.03, 58.75 and 36.26mg/kg fish/hr for the JJ, JK and KK strain, respectively, during the daytime. The value of the KK strain was significantly lower than that of the JJ and JX shuin (P<0.05), however daily TAN excretion rates of the JJ, JK and KK strain were not different (P>0.05). When fish were fed at satiation after 4 days of starvation, TAN excretion rates reached the maximum values 4 hours after the feeding fur the KK (31.23 mg/kg fish/hr) and 6 hours after the feeding fur the JJ (44.19 mg/tg fish/hr) and JK strain (41.70 mg/kg fish/hr). After 3 days of starvation, the daily endogenous TAU excretion rates (ETE) for the JJ, JK. and KK strain were 286.91, 215.66 and 179.29mg/kg fish/day, respectively. The value of the KK strain was lower than that of the JJ and JK strain (P<0.05). The total feces production rates of the JJ, JK and KK strain were not significantly different, however the proportions of feces production rates by time for the JJ, JK and KK strain were different (P<0.05). As overall results, efficiency of dietary protein utilization of JJ, JK and KK seems to be different and KK strain could offer a desirable option for aquaculture purpose.

• Analytical Science and Technology
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• v.18 no.3
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• pp.250-256
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• 2005

A selective method of high performance liquid chromatography with UV detector has been applied to determine 4 tetracycline antibiotics in the animal food, simultaneously. The targets were chlortetracycline (CTC), doxycycline (DC), oxytetracycline (OTC), and tetracycline (TC) that are used routinely in veterinary medicine for prevention and control of disease. Food samples were beef, pork, chicken, milk, whole egg, flatfish (Limanda yokohamae), jacopever (Sebastes hubbsi), seabream (Chrysophrys major), eel (Anguilla japonica) and lobster (Hommarus americanus). After extracting food samples with 20% trichloroacetic acid and McIlvaine buffer, they were purified by a $C_18$ SPE cartridge with 0.01M methanolic oxalic acid solution. The concentrated residue was re-dissolved in methanol, filtered, cleaned up and analyzed on a $C_18$ column. The mobile phase was a mixture of 0.01M oxalic acid and acetonitrile with a gradient ratio from 85:15 to 60:40. The UV wavelength was 365 nm. The overall recoveries were ranged from 71% to 98% and the limit of detections were 0.022 for CTC, 0.012 for DC and OTC and 0.009 mg/kg for TC at signal/noise > 3, respectively. As results, CTC, DC and TC were not detected in all selected food samples, however, OTC was detected in meat and fishes. The determined level of OTC was 0.04 ppm for pork, 0.17 ppm for flatfish and 0.05 and 0.08 ppm for jacopever, that were within the Maximum Residue Limits (MRLs) in the food.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.707-712
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• 1998

Seasonal variation in the proximate composition, cholesterol (CHOL) and $\alpha$-tocopherol ($\alpha$-Toc) content of 12 spices of fish muscle, which caught off Tongyeong coast of the Southern Sea (Nam-Hae) from Mar. 1995 to Feb. 1996, was studied. Lipid and moisture content showed remarkable seasonal variation and there were a negative correlation between the both (r= -0,85, p<0.001), while protein and ash content unchanged almost through the sampling period. The lipid content of anchovy, hickoryshad, black sea bream, finespotted flounder sea eel, bastard, and file fish was high in Dec. Oct. Nov. Jan. Jan. Nov, respectively, and low in the season corresponding to their spawning period. However, in case of striped mullet, yellow tail, mackerel, rock fish and red sea bream, there was no correlation between their lipid content and spawning period, and thus these fishes fore considered to be affected more by water temperature and the content of their diet. CHOL content increased In :he season containing a high level of lipid, whereas $\alpha$-Toc content unchanged almost through the sampling period.

• Journal of fish pathology
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• v.13 no.2
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• pp.121-127
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• 2000

From August to October 1998, over 60% mortality of cultured striped beakperch Oplegnathus fasciatus was occurred in net cages along the southern coast of Korea. Moribund fish showed some clinical signs of lethargic behavior, dark coloration or decoloration, severe gill anemia and enlargement of spleen. Also enlarged basophilic cells showing Feulgen -positive reaction were observed in the tissue section of spleen, kidney, liver and heart of the diseased fish. GF cells inoculated with spleen homogenate of diseased fish produced cytopathic effect of enlarged and rounded cells, therefore the causative virus was isolated from diseased fish. Striped beakperch fingerlings intraperitoneally inoculated with the causative virus ($10^4TCID_{50}$/0.1 ml) revealed symptoms similar to those of naturally infected fish and died from 7 to 14 days post injection. Transmission electron microscopy revealed that the causative virus was enveloped icosahedral particle with 120~130 nm in diameter. PCR products of the expected size (500 bp) were amplified with a primer set based on the ATPase gene of RSIV(red sea bream iridovirus) using template DNAs which were extracted from the spleen of diseased fish and GF cells inoculated with the causative virus. According to the analysis of nucleotide sequence of these PCR products, the sequence from ATPase cDNA gene of the causative virus showed 95% homology with that of RSIV. These results indicate that the mass mortality in the cultured striped beakperch was caused by the infection of iridovirus similar to RSIV.

• Journal of Food Hygiene and Safety
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• v.36 no.4
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• pp.331-341
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• 2021

DNA barcode sequences of commercial seafood products, which are difficult to morphologically discriminate, were analyzed to determine cases of food fraud. The gene sequences were analyzed by amplifying the COX I (cytochrome C oxidase subunit I) gene region of mitochondrial DNA, which is mainly used for species identification. The DNA barcode sequences were compared with the gene sequence of each fish registered in the US National Center for Biotechnology. A total of 46 processed seafood products (12 Pagrus majo, 4 Oplegnathus fasciatus, 7 Dentex tumifrons, 2 Acanthopagrus schlegelii, 7 Oreochromis niloticus, 6 Branchiostegus japonicus, 8 Branchiostegus albus) were investigated. Having DNA sequence identity of more than 97% was judged as the same species. As a result of this study, no cases of forgery and alteration were detected. However, some disparities in the commercial names used in local markets and the standard names given in the Korea Food Code were found, which may cause confusion for consumers. It is therefore suggested that the standard name or scientific name be displayed on seafood product labels.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.81-86
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• 1968

A porgy was divided into eight parts. After drying at low temperature and pulberizing it, the sample was hydrolyzed by $Ba(OH)_2{\cdot}8H_2O\;at\;120^{\circ}C$, under the pressure of $1\;kg/cm^2$ for 8 hours. Tryptophan was determined by means of microbiological assay, using Lactoba-cillus arabinosus 17-5. The result of experiments was as follows: The content of nitrogen of eight parts of the body amounted $12.55\%$ in muscle being the highest of all, $11.49\%$ in heart, $11.31\%$ in eyeball, $11.22\%$ in liver, $11.06\%$ in intestine, $8.75\%$ in head, $7.81\%$ in gill, and $6.02\%$ in fin which was the lowest of the parts tested. The content of tryptophan per 1 gram nitrogen was 11.79mg in liver, which was the highest of all, 10.11mg in heart, 9.76mg in eyeball, 8.77mg in intestine, 6.28mg in muscle, 5.72mg in head, 4.03mg in gill 2.64mg in fin, and in that order.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.2
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• pp.163-169
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• 2018

This study examined the expression of heat shock protein 70 (Hsp70) in red seabream Pagrus major infected by the, acanthocephalan parasites Longicollum pagrosomi. We cloned the full-length Hsp70 cDNA from the liver of the red seabream. The full-length cDNA had a 1,950 bp open reading frame (ORF) that encoded a protein of 650 amino acids. The deduced amino acid sequence of Hsp70 contained all of the conserved Hsp70 family signature sequences and an adenosine triphosphate (ATP)/guanosine triphosphate (GTP) binding motif, including the EEVD (consensus sequence that terminates in Hsp70 family) consensus sequence. The expression of Hsp70 mRNA was upregulated int the fish head-kidney and liver, as determined by quantitative real-time PCR. We quantified the Hsp70 mRNA expression in normal red seabream and fish infected fish by L. pagrosomi. The expression of Hsp70 mRNA was significantly higher in the infected red seabream. These results suggest that Hsp70 play a role of protection against stress and inflammation caused by the parasite and may help maintain homeostasis.