• Journal of Aquaculture
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• v.19 no.4
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• pp.315-322
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• 2006

The objective of the present study was to investigate the expression of heat shock protein 90 (HSP90) and 70 (HSP70) mRNA as cellular stress responses, the levels of plasma cortisol with glucose as neuro-endocrine stress responses during water temperature rising in freshwater adapted black porgy, Acanthopagrus schlegeli. A cDNA fragment of 891 (HSP90) and 465 (HSP70) bp was cloned from black porgy testis by Reverse transcription-polymerase chain reaction (RT-PCR) with primers designed from the conserved regions of other teleost. The PCR product of HSP90 showed very high homology to red seabream (99%), rainbow trout (95%), Atlantic salmon (94%), zebrafish (94%) HSP90, HSP70 of black porgy was also highly similar to those of rainbow trout (96%), silver seabream (95%), zebrafish (95%) HSP70. Water temperature rising ($20{\sim}30^{\circ}C$) induced elevation of HSP90 mRNA in black porgy gonad, liver, brain, intestine and kidney, whereas it resulted in an induction of the HSP70 mRNA expression in gonad only. Plasma cortisol levels increased significantly at $30^{\circ}C$ in the fish compared to those at $20^{\circ}C$. Glucose levels of the fish showed a tendency of co-increase with cortisol during water temperature rising. These results suggest that increased HSP90 mRNA in liver with plasma cortisol following heat shock may be related to increasing glucose for homeostasis in this species.

• Journal of Aquaculture
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• v.15 no.1
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• pp.31-37
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• 2002

Effect of 2,4-Dichlorophenoxy acetic acid (2,4-D) on vitellogenin (VTG) production and estrogen ($E_2$)-estrogen receptor (ER) binding affinity were examined in primary hepatocyte cultures of rainbow trout, Oncorhynchus mykiss. Hepatocytes were pre-cultured for 2 days; subsequently, $E_2$( 2$\times$$10^{-6}$/ M) and 2,4-D ($10^{-9}~10^{-6}/M$) were simultaneously added to the incubation medium. They were cultured for more than 5 days. VTG and $E_2$-ER binding affinities were analyzed by SDS-PAGE and ELISA, respectively. 2,4-D concentration used had no appreciable effect on the morphology, viability, and DNA content of hepatocytes in culture. It had also no effect on VTG production. However, it interfered with $E_2$-ER binding affinity, which was reduced with increasing concentration of 2,4-D. The affinity was inhibited by 25 and 30% at $10^{-7}$ M and $10^{-6}$ M of 2,4-D, respectively. This result suggested that although 2,4-D had no effect on VTG production, it acted as reno-estrogenic contaminant in ER.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.232-239
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• 1994

In order to determine the utilization of ascidian tunic, which has been blamed for problems of costal environmental pollution when discharged into the sea after being used as a natural dietary pigment sources for rainbow trout(Oncorhynchus mykiss), fingerlings were fed on experimental diets containing acetone-extracts for 6 weeks. The amounts of acetone-extracts were 11,000mg/Kg and contained 50mg/100g wet tissues of carotenoid and $6\%$ of carotenoids were astaxanthin. From the results of feeding experiments, the growth rate in the extract group was a little higher than that of the control and pink groups after 6 weeks. The redness and yellowness of the fish skin and muscle in the extract group were similar to the pink group. Therefore, acetone-extracts of ascidian tunic were judged to be a natural dietary pigment source suitable as a substitute synthetic pigment for aquaculture use.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.240-246
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• 1994

This study was designed to determine the optimum pigment concentration supplemented in diet and feeding periods on the pigmentation of rainbow trout(Oncorhynchus mykiss) by using acetone-extracts of ascidian tunic as a natural pigment source. The eight pigmented diets contained carotenoid of ascidian tunic extracts at concentrations of 0, 200, 400, 800, 1,600 and 3,200mg/kg of diet, carophyll pink at concentration of 800mg/kg and commercial diet. No difference in pigment concentration was found between the ascidian extracts group and the control group until 4 weeks, but the redness of muscle and integument in the 1,600, 3,200mg/kg diet and carophyll pink was increased in the dorsal and caudal areas of fish from 6 weeks of age. In the sensory panel test, fish fed the ascidian tunic extracts diet were similar to those fed the carophyll pink diet. The optimum concentration and feeding periods for pigmentation of rainbow trout was found to be ascidian tunic extracts of 1,600mg/kg diet for 8 weeks.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.2
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• pp.103-109
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• 2000

Complete senuences of the mitochondrial rRNA Benes were determined among six salmonines in Korean Waters (Brachpmystax lenok, Onoorhpchus keta, O. masou mason, O. mason ishikawae, O. mykiss, and albino mutant of O. mykiss). The purposes of this study were to provide the basic information on levels of mtDNA polymorphism among these species for genetic characterization; discuss phylogentic relationships among three Oncorhynchus sepecies; demonstrate the utility of rRNA gene sequence data as a genetic marker for disringuishinf among Korean salmonines. PCR/direct sequencing data indicated the following consistent results; 1) 12S rRNA genes was 945 bases long in Oncorhynchus species, and 946 bases in B. lenot including one insertion. 2) Of sequence variation in mitochondrial rRNA regions, transitional substitutions were superior to transversion. 3) The significant differences were not shown in the intraspecific variation values in these gene regions. The percentage sequence divergence values were ranged from $0.066 to 0.212{\%}$. 4) The interspecific divergences were greater than the intraspecific variation. Nevertheless, ribosomal RMh genes were more conserved among species than the other mitochondrial genes, and they showed potentiality as an intergenic marker for systematics. In addition, phylogenetic trees, constructed from this data, supported that cherry salmon was closer to chum salmon than to rainbow trout, and that lenok was most distantly related species in six salmonid species.

• Journal of Aquaculture
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• v.11 no.3
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• pp.311-317
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• 1998

Effects of Cu and Zn on estradiol-17$\beta$-Induced vitellogenin (VTG) production were electro-phoretically examined in hepatocyte cultures of rainbow trout. Hepatocytes were precultured for 2 days and then Cu ($10^{-5}$ ~$10^{-4}$M) and Zn ($10^{-5}$~$10^{-3}$M) were added to the incubation medium with estradiol-17${\beta}$ ($2{\times}10^{-6}$M). The hepatocytes were cultured for 5 more days. The relative VTG production rate was expressed as the percentage of VTG to total proteins including the VTG. The addition of CU and Zn to the incubation medium had no appreciable toxin effect on the viability of hepatocytes in the culture. However, Cu markedly reduced VTG production at any concentration used. Zn also specifically reduced VTG production by hepatocytes in a concentration dependent way and there was a significnt reduction at Zn concentrations of $10^{-3}$M. The reduction recovered by removing Zn from the media, but Cu did not. Additionally, enriched Ca concentrations (1.8 to 2.5 or 5.0 mM) in the incubation medium had no protective effect on the reduction of VTG production by Cu $10^{-4}$ M. These results suggest that the production of VTG is more susceptible to Cu and Zn than are other hepatocyte-derived proteins.

• Journal of Aquaculture
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• v.8 no.2
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• pp.141-148
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• 1995

For the mass production of all-female triploid rainbow trout during fall season, treatment of short-term daylength from 30th of August, 1994 and chromosome manipulation by heat shock were performed with 3-year-old fish. After treatment of short-term daylength to fish, we successfully obtained the fertilized eggs from all treated fishes. However, hatching rate were significantly lower than that of natural spawning season (P<0.05). Hormonal treatment using 3mg of $17\alpha-methyltestosterone$ per kg of diet for 55 days at $16.5^{\circ}C$ gave $100\%$ of sex-reversed male (masculinized female) population. When the fertilized eggs were treated with the various conditions of heat shocks survival rates and triploid incidencies were varied, and ranged from 15.0 to $88.2\%$ and 36.7 to $100\%$, respectively.

• Journal of Aquaculture
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• v.10 no.3
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• pp.347-356
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• 1997

Feeding experiment was conducted to evaluate effects of dietary soybean meal (SBM) on the phosphorus bioavailability of rainbow trout (Oncorhynchus mykiss). Seven diets, containing 0~70% SBM, were made based on iso-nitrogenous and iso-caloric basis of 44% crude protein. Ajpparent digestibility of phosphorus was measured 60 and 120 days after feeding. The digestibility coefficient increased gradually as the level of SBM increased up to 46~58%, but decreased at 58~70% SBM level. Phosphorus concentrations in feces decreased with an increased in dietary SBM level. Patterns of post-prandial phosphorus excretion were not similar to those of ammonia excretion, but the amount decreased with the increased SBM level in the diets. Total excretion of phosphorus for 24 hours was 19.68mg.kg-1 body wt..day-1 in the control group, but excreted phosphorus by the 58% and 70% SBM groups was 63.4% and 56.1% of the control group, respectively. Phosphorus concentration of whole body decreased with an increase in dietary SBM level for 120 days of feeding. However, there were no significant differences in phosphorus concentrations of liver among the experimental groups, except for 70% SBM diet group.

• Journal of fish pathology
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• v.25 no.3
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• pp.271-277
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• 2012

The practical monitoring was performed to survey the mortalities in aquaculture farms of olive flounder, rockfish, rainbow trout, Japanese eel, white shrimp and abalone in South Korea from May to November, 2011. The aquatic organism disease inspectors, who have the national licenses for the diagnosis and prevention of aquatic disease and have close relationship with the farms, investigated the rates and causes of mortalities according to the standard manual. In 70 flounder farms, the cumulative mortalities rate was 27.9%, and the mortalities were caused by scuticociliatosis, streptococcosis, VHS, non-infectious loss, vibriosis and gliding bacterial disease. The moralities rate of 30 rockfish farms was 13.6%, and those were mainly contributed by gill flukes and streptococcosis. Most of mortalities of rainbow trout were caused by non-infectious loss and protozoan white spot disease. The mortalities rate of Japanese eel was 0.6% by edwardsiellosis, protozoan white spot disease and gill flukes. The loss rate of white shrimp was 71.2%, and most of them was related with non-infectious ones, such as carnivalization, transportation loss, and the rest was caused by viral white spot disease. The mortalities rate in the abalone farms was 10.7% and all of them were related with non-infectious loss.

• Journal of fish pathology
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• v.11 no.1
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• pp.51-60
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• 1998

Concerned to the lyfe cycle of Ichthyophthirius multifiliis, the experimental infection and development of the parasites were studied in the several freshwater cultured fishes. Opitimum conditions for the propagation of the parasite by serial passage with the rainbow trout fry was observed. Visiable white spots were examined in the body surface, fins and gills of the healthy fries, and a stable infection has been maintained for 2 months in the experimental system (Temperature: $18{\pm}1^{\circ}C$ DO: 7-7.5 ppm; pH: $7{\pm}0.2$). Induction conditions for artificial infection of the parasite by interms of the host fishes, stages of the parasites, and rearing temperature regimes was investigated. Rainbow trout fries showed a positive infection which was resulted from exposure of theront at $18^{\circ}C$. The rainbow trout fries induced white spots on the body surface at 3-7 days exposure to the theronts at $18^{\circ}C$. It was found that exposure of the rainbow trout fries exposed to 1,000 theronts per fish (10 theront/ml) for 45-60 minutes at $18^{\circ}C$ would consistently produce infection. Perfect infection (100%) was induced when the fries were exposed to 1,500 theront per fish (15 theront/ml) under laboratory condition. Development of I. multifiliis in the rainbow trout was observed for 7 days postexposure (PE). The parasite increased in average diameter from $54{\mu}m$ on the 1st day PE to $426{\mu}m$ on the 7th day PE. In the initial infestation period, the parasites were found on the gill epithelium, and on the 3rd day PE they invaded into the basal part of the gill filament adjacent to the major blood vessels, particularly the afferent vessels. Morphological change of buccal apparatus were observed on the 2nd day PE. Contractile vacuoles were more prominent on the 4th day PE, and they had notable changes on the 7th day PE.