• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.355-361
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• 2011

Effects of aluminum (Al) on plasma vitellogenin (VTG), alkaline-labile phosphorus (ALPP), calcium (Ca), glutamate pyruvate transaminase (GPT), the hepatosomatic index (HSI), and hepatic Al concentration were examined in estradiol-$17{\beta}$ ($E_2$)-administered immature rockfish Sebastes schlegeli. Fish were injected intraperitoneally with $E_2$ (5 mg/kg body weight [BW]) and/or Al (0, 0.1, 1, 5, and 10 mg/kg BW) and plasma and liver samples were extracted 7 days later. After sodium dodecyl sulfate polyacrylamide gel electrophoresis, the relative amount of VTG was determined by integrated optical density. VTG accounted for 23.6% of the total proteins in the control group, but this value decreased with increasing Al administration. Al reduced the concentrations of ALPP and Ca in a concentration-dependent manner and significant reduction occurred at Al concentrations greater than 5 mg/kg. The concentration of GPT increased in a concentration-dependent manner in all Al-administered rockfish. The concentrations of Al in the liver also increased, and HSI was decreased, in a concentration-dependent manner. These results suggest that Al inhibits $E_2$-induced VTG production by being toxic to hepatocytes in marine fish.

• Development and Reproduction
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• v.24 no.3
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• pp.225-230
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• 2020

This study reports the presence of mature and bi-sexual phase gonads in red spotted grouper, Epinephelus akaara after less than a year of cultivation in a commercial indoor tank and a net cage. In December 2018, juveniles were placed in an indoor tank and cultured for five months. In June 2019, the fish were transferred to a net cage and cultured until September. The rearing temperatures ranged from 19.86℃-24.65℃ in the indoor tank and 21.86℃-27.65℃ in the net cage. During the net cage culture period, specimens were randomly selected for histological gonad examination. The highest gonadosomatic index (GSI) value was measured in July (3.38±2.53), and dramatically decreased in August (0.44±0.21) and September (0.42±0.30). In July, some mature fish showed signs of vitellogenic stage oocyte development (vitellogenic and oil droplet stage oocytes), but immature fish were in an early developmental stage containing peri-nucleolus stage (PNS) oocytes. Bi-sexual phase gonads containing spermatocytes and spermatids were observed in the lumen and several PNS oocytes. By August and September, most specimens showed early-stage ovary development. However, mature testis (in August) and bi-sexual phase gonads (in September) were also observed. These results provide evidence for early puberty and hermaphroditism in the red spotted grouper.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.1
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• pp.24-30
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• 2007

We developed an ecosystem indicator (EI) for the coastal and offshore areas of Korean waters. One of the major scientific challenges of this undertaking was to translate broad policy statements for ecosystem-based fisheries management (EBFM) into practical terms. Fish reproduction potential (FRP) was defined as an EI to describe the reproductive probability of adult fisheries resources in Korean waters. The FRP was estimated as the ratio of adult fish composition to total catch, catches (in metric tons) by species and by ecosystem, and fishery effort (in horse power per metric ton). The FRP indices of the East/japan Sea Ecosystem (EJSE), Yellow Sea Ecosystem (YSE), and East China Sea Ecosystem (ECSE) began to decrease after the mid-1980s, and the current indices have decreased further, at 0.63 (EJSE), 1.22 (YSE), and 0.68 (ECSE) index points compared to the indices of 1975, when similar catch amounts were recorded. Lower FRPs in the Korean marine ecosystems were the result of higher proportion of immature fisheries resources in the total catch. Because this kind of ecosystem-level indicator is thought to reflect scientific approaches to EBFM and to provide an important tool for assessing the current status of marine ecosystems with respect to both quantity and quality, more EIs should be developed for Korean waters.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.2
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• pp.253-259
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• 1997

Objective: To investigate effects of cryoprotectant and cryopreservation on the chromosome of the human immature oocytes. Design: Intact cumulus-enclosed immature oocytes were collected from unstimulated ovaries and divided into three groups, such as no treatment as control (group 1), only 1,2-propanediol (PROH)-treated (group 2), and cryopreserved oocytes (group 3). Oocytes in group 1, 2, and survived oocytes after cryopreservation in group 3 were cultured for 48 hours. Setting: Infertility Medical Center at the CHA General Hospital, Seoul, Korea. Patients: Oocytes were obtained from Patients undergoing gynecological surgery. Main Outcome Measures: Maturation rate, abnormality in chromosomes by fluorescence in situ hybridization (FISH). Results: There was no effect of PROH only treatment on the chromosomal abnormalities in group 2 compared to control oocytes (41.4% and 31.8%, respectively). Whereas significantly increased abnormalities in chromosome (77.8%) were found in group 3. Conclusions: Human oocytes matured in vitro after cryopreservation at the germinal vesicle (GV) stage showed increased incidence of chromosomal abnormalities. These abnormalities may impair the capacity for further development of the embryos derived from frozen-thawed oocytes.

• Development and Reproduction
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• v.16 no.2
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• pp.121-128
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• 2012

Kisspeptin has been reported to facilitate sexual maturation and ovulation by directly stimulating GnRH neurons via its receptor, GPR54. The KiSS-GPR54 system is playing an important role in the reproduction of several mammalian species. However, little is known about their function in fish. The aim of this study is to understand the physiological function and evolutionary conservation of KiSS-GPR54 system in teleost fish blacktip grouper, Epinephelus fasciatus. In the present study, we have partial cloned KiSS1, KiSS2 GPR54 mRNAs from a brain samples. Tissue distribution analysis using RT-PCR revealed that the KiSS1, KiSS2, GPR54 transcripts were expressed in different tissue. The KiSS-GPR54 system in gonadal of immature and mature stage were analyzed using qRT-PCR. The partial sequence of KiSS1, KiSS2, GPR54 were 232 bp, 304 bp, 613 bp long, respectively. KiSS1, KiSS2, GPR54 mRNAs are shown common expression in the brain. The amount of KiSS1, KiSS2 mRNAs expression were significantly higher in mature stage than immature stage. However GPR54 mRNA expression was higher in immature stage. These results are in good agreement with the hypothesis that KiSS-GPR54 system plays an important role in the regulation of reproductive function in the blacktip grouper.

• Fisheries and Aquatic Sciences
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• v.17 no.2
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• pp.223-227
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• 2014

The present study examined whether light emitted by long-afterglow phosphorescent pigments (LumiNova) would stimulate gonadal development in fish during the nonbreeding season. Pellets containing LumiNova powder (treatment group) were prepared and placed on the calvaria of specimens of the sapphire devil Chrysiptera cyanea, a reef-associated damselfish that requires long days for gonadal recrudescence. A pellet without LumiNova powder was placed on the calvaria of the control fish (control group). Fish were reared at $26^{\circ}C$ under a light-dark cycle (12 h photophase, 12 h scotophase; LD 12:12) for 4 weeks. No difference in the gonadosomatic index (GSI) or ovarian histology was observed among the control, sham-operation, and treatment groups 1 week after the start of the experiment. After 4 weeks, the GSI of the control and sham-operation groups remained at low levels, and ovaries contained immature oocytes at the perinucleolus stage. In contrast, the treatment group exhibited significantly higher values of GSI as well as developed ovaries with fully vitellogenic oocytes. These results demonstrated that long-day conditions were produced by light emitted from the LumiNova pellets, thus stimulating ovarian development in the damselfish. Therefore, long-afterglow phosphorescent pigments can be used as an alternative to standard light sources for purposes of artificial stimulation of gonadal development in fish.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.403-410
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• 2011

Scartelaos gigas is an amphibious mudskipper species that inhabits mud flats in Korea, China, and Taiwan. This fish is at risk of extinction because of its very restricted habitat and overexploitation. Information about this fish's reproductive characteristics is needed for species conservation. The sexual maturity and early life history of S. gigas were investigated through histological methods and direct observation of eggs in the wild, respectively. In total, 560 individuals of S. gigas were collected with the aid of fishermen from March 2003 to October 2003 at Jung-do Island, southwest Korea. Through microscopic observations of gonadal development, it was determined that S. gigas of both sexes were immature in April, but began to reach maturity in May, and were then fully mature by June, which was maintained until July. In August, some female fish developed early oocytes, but by September oocytes were observed to have degenerated and had been absorbed. Spawned eggs were elliptical and had an average size of 1.37 mm (long axis) by 0.69 mm (short axis). The newly hatched larvae (3.03 mm total length, TL) had an open mouth and anus, two melanophores near the anus, and one large melanophore between the 18th and 19th myomeres. The larvae (3.18 mm TL) showed absorption of the yolk and oil globule within 5 days after hatching and became prelarvae. This species should be considered vulnerable or conservation-dependent, and thus parental fish need to be protected from fishermen during the main spawning season (June).

• Journal of fish pathology
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• v.17 no.3
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• pp.191-198
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• 2004

Temporal changes of plasma vitellogenin (VTG), alkaline-labile protein phosphorus (ALPP), calcium (Ca), glutamate pyruvate transaminase (GPT) and hepatosomatic index (HSI) were examined in the $estradiol-17\beta$ ${E_2}$-administered immature rockfish, Sebastes schlegeli. Fish were intraperitoneally injected with ${E_2}$ (5 ㎎/kg B.W.) in 70% ethanol and then plasma were extracted at 0, 1, 3, 6, 9, 12 and 15 days. VTG band was detected at a molecular weight position of about 170 kDa on Day 3 in SDS-PAGE. This band became more distinct at 6 days but its was gradually thinned with time-course, and not detected at 15 days. Plasma ALPP and Ca increased suddenly at 1 day and the highest concentrations were detected at 6 days and then these concentrations decreased gradually with time-course. ALPP and Ca concentrations at 15 days after E2 administration were very similar to that before E2 administration. GPT was increased at 1 day and higher GPT was detected at 3 days. However, GPT was gradually decreased with time-course. GPT and HSI at 15 days after E2 administration were also very similar to that before E2 administration. HSI was also increased at 1 day and the highest value was detected at 3 days and then gradually decreased with time-course. These results suggest that plasma ALPP, Ca, GPT and HSI could be utilized as a biomarker of exogenous E2 exposure in coastal ecosystem, because the changes of ALPP, Ca, GPT and HSI after E2 administration are very similar to that of VTG.

• Korean Journal of Veterinary Research
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• v.47 no.3
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• pp.299-302
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• 2007

Neoheterobothrium hirame (N. hirame) is a large blood-feed gill-worm infecting the highly prized olive flounder. The present study was reported the occurrence and elimination of Neoheterobothrium infection from young cultured oliver flounder in the western coast of Korea. Flounder (weight 18-25 g, length 10-15 cm) were obtained from a cultured farm at Taean of Korea at May 2006. A lot of flounder died with serious anemia. We isolated N. hirame from the buccal cavity wall of dead flounder. Adult parasites were 5-15 mm in total length, with 4 pairs of clamps on the pedunculated haptor and isthmus region embedded in host tissue, while immature and sub-adults were identified the attachment to the gill filaments, rakers and arches with the clamps. All fish with infection were treated with 8% NaCl-supplemented seawater for 1 and 10 min at $22^{\circ}C$, respectively. The significant reduction in mortality (6.7%) was observed among fish treated with 8% salt water for 10 minutes, when compared with that of non-treatment group (100%).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.416-429
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• 2010

The market-based fisheries resources management system was reviewed and the improvement scheme was studied for seeking the sustainability of marine ecosystems and their fisheries resources. A demand-side policy is currently emerging to the management of fisheries resources by reducing over-exploitation, based on the consumer's selection. The role of consumers in the sustainable fishery was studied by comparing the social responsibility and consumer's activity between Korea and foreign countries and international NGO groups, based on the FAO guideline. The adoption of the Marine Stewardship Council (MSC)'s eco-labelling certificate was suggested by expanding the existing environment-friendly certification system in Korea. This new system will contribute to the protection of young immature fish and spawners in coastal and offshore fisheries as well as to the international trade of seafood in terms of fish products from well-managed fisheries. It is noted that the consumer's activities in the markets as regulators will contribute to the ecosystem health and sustainability.