• Development and Reproduction
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• v.18 no.1
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• pp.13-23
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• 2014

This study is conducted to monitor the morphological developmental features of the egg development, larvae and juvenile of Epinephelus septemfasciatus, the fertilized eggs were gotton using artificial insemination. Matured parents are collected from marine caged fish farms in Geomun-ri, Samsan-myeon, Yeosu-si, Jeollanamdo Korea in June 2012. The fertilized eggs were pelagic eggs containing one oil globule, and measured 0.81~0.89 mm ($0.85{\pm}0.04mm$, n=50) in diameter. In regard to rearing environment, the water temperature is $21.0{\sim}23.0^{\circ}C$ and the salinity is 32.0~33.2‰. Hatching was observed from 48 hours after fertilization, the mouth and anus of prelarvae was not opened but had egg yolk at newly hatched. 4 days after hatching, the mouth and anus of postlarvae was opened and began to eat Rotifer and was measured 2.40~2.49 mm ($2.45{\pm}0.03mm$ n=10) in total length. 12 days after hatching, postlarvae was measured 3.77~4.67 mm ($4.27{\pm}0.33mm$) in total length, its the second pole tide of dorsal fin and the first pole tide of pelvic fin was extended longitudinally. 71 days after hatching, juvenile was measured 40.5~45.4 mm ($42.6{\pm}2.04mm$) in total length. Seven bands were observed in body, and pole tides of dorsal and pelvic fins were shortened.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.3
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• pp.237-241
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• 2002

This study was performed both to explore the host of nervous necrosis virus (NNV) between mariculturing fish species and to examine the phylogenic position of the NNV in Korea. NNV was confirmed on the basis of histopathological and molecular biological examination, then VNN infection was Preyed from either moribund or dead fishes including red drum, Sciaenops ocellatus; oblong rock fish, Sebastes oblongus and flounder, Paralichthys olivaceus. As a result of sequencing for a part of ms, virus from red drum was showed $98\%, $97\%, $86\% and $74\% homology with oblong rock fish, grouper, Japanese flounder and striped jack, respectively. On the other hand, NNV from oblong rock fish was demonstrated $96\%, $85\% and $72\% homology with grouper, Japanese flounder and striped jack, respectively. NNV from red drum and oblong rock fish was exhibited phylogenically distant from the representative NNV, SJNNV originated from striped jack. On the contrary, the viruses appeared to be similar species with Taiwan NNV isolated from culturing grouper.

• Development and Reproduction
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• v.20 no.2
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• pp.81-90
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• 2016

The effect of sudden changes of water temperature (WT) on the survival rate and physiological responses of the red spotted grouper (Epinephelus akaara) were examined by manipulating WT control system for 9 days. Experimental condition was divided in two different regimes at low (from $10^{\circ}C$ to $4^{\circ}C$, decreased $1^{\circ}C/d$) and high (from $28^{\circ}C$ to $34^{\circ}C$, increased $1^{\circ}C/d$) WT. Survival rate of experimental fishes were observed, and determined the changes of hematological characteristics by analyzing plasma levels of cortisol, glucose, total protein, and electrolytes ($Na^+$, $Cl^-$, $K^+$). No mortality was observed until low WT $6^{\circ}C$ (144 h) and high WT $32^{\circ}C$ (96 h), and 100% mortality was observed at low WT $4^{\circ}C$ (216 h) and high WT $35^{\circ}C$ (171 h). Plasma levels of cortisol and glucose increased rapidly as decreasing WT, and the loss of swimming ability and respiration response was observed at low WT $7^{\circ}C$ and high WT $34^{\circ}C$ conditions.

• Genomics & Informatics
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• v.20 no.3
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• pp.33.1-33.17
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• 2022

Nervous necrosis virus (NNV) is a deadly infectious disease that affects several fish species. It has been found that the NNV utilizes grouper heat shock cognate protein 70 (GHSC70) to enter the host cell. Thus, blocking the virus entry by targeting the responsible protein can protect the fishes from disease. The main objective of the study was to evaluate the inhibitory potentiality of 70 compounds of Azadirachta indica (Neem plant) which has been reported to show potential antiviral activity against various pathogens, but activity against the NNV has not yet been reported. The binding affinity of 70 compounds was calculated against the GHSC70 with the docking and molecular dynamics (MD) simulation approaches. Both the docking and MD methods predict 4 (PubChem CID: 14492795, 10134, 5280863, and 11119228) inhibitory compounds that bind strongly with the GHSC70 protein with a binding affinity of -9.7, -9.5, -9.1, and -9.0 kcal/mol, respectively. Also, the ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties of the compounds confirmed the drug-likeness properties. As a result of the investigation, it may be inferred that Neem plant compounds may act as significant inhibitors of viral entry into the host cell. More in-vitro testing is needed to establish their effectiveness.

• Development and Reproduction
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• v.11 no.2
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• pp.105-109
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• 2007

This study examined temperature effect in egg development and hatching of longtooth grouper, Epinephelus bruneus. Fertilized embryos was not growth after morula stage at $15^{\circ}C$, at 18, 21, 24 and $27^{\circ}C$, the required time from fertilized embryos to hatching were 70 h. 30 min., 44 h. 10 min., 29 h. 10 min. and 24 h. 30 min., respectively. The hatching rates at $24^{\circ}C$ were higher than the other conditions and the hatching was not occurred at $15^{\circ}C$. These results suggest that the water temperature range of egg development and hatching was $18{\sim}27^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.847-852
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• 2014

The aim of this study was to investigate the effects of stocking density and water temperature in the rearing of the longtooth grouper Epinephelus bruneus. Juvenile fish [mean body weight (BW)=$6.9{\pm}1.1g$] were raised for 6 weeks, in four density groups of 0.25, 0.5, 0.75, and 1 individuals/L. There were no significant differences in weight gain (WG) or specific growth rate (SGR) among the density groups; however, both WG and SGR tended to be higher in the low density group. After 6 weeks of rearing in temperature-controlled water ($23.6{\pm}0.8^{\circ}C$) and ambient temperature water ($19.6{\pm}1.8^{\circ}C$), there were no significant differences in WG or SGR values, but both tended to be higher in the temperature controlled water. The feed efficiency (FE) and daily feed intake (DFI) and WG values were also higher in the temperature-controlled water than in the ambient temperature water. WG values were lower at lower water temperatures. The same pattern was observed for SGR, FE, and FI, all of which exhibited lower values at lower temperatures. In particular, WG, SGR, and FE values all tended to decrease at the $16^{\circ}C$ water temperature. The effects of water temperature on 1-year fish (mean BW = $387.6{\pm}30.2g$) and 3-year fish (mean BW = $1,338.3{\pm}73.8g$) were similar to those of the juvenile fish (0-year fish).

• Journal of Marine Life Science
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• v.7 no.1
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• pp.45-51
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• 2022

The profer salinity range for aquaculture of hybrid grouper (Epinephleus bruneus♀ × Epinephleus lanceolatus♂) were evaluated in terms of their survival, growth, feed intake and physiological responses after 30 days of exposure to different salinities (0 psu, 3 psu, 5 psu, 10 psu, 15 psu, 20 psu, 25 psu, 30 psu). Hybrid grouper all died at 0 psu salinity on the 4th day of exposure but all hybrid survived at a salinity of 5 psu or higher during the exposure period. Body length and weight increased above 5 psu salinity and the growth rate was the highest at 30 psu. Hybrid exposed to 3 psu did not eat the feed pellet. Feed intake did not show a significant difference between salinity 20 psu, 25 psu and 30 psu. Plasma osmolality of the juvenile hybrids exposed to different salinities was 341~368 mg Osmol/kg above 5 psu. The oxygen consumption rate was the highest at 30 psu with 163.6±22.3 mg O₂/kg fish/h. SOD, CAT and GSH-PX were significantly higher at 15 psu. Therefore, the critical salinity for survive of the juvenile hybrid was 5 psu, and the proper salinity for optimal culture was analyzed with 20~30 psu.

• Journal of Aquaculture
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• v.10 no.1
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• pp.55-61
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• 1997

The experiment was conducted to understand the effect of HCG upon ovulation induction and egg maturation in the sevenband grouper, Epinephelus septemfasciatus, as a part of the research for its resources management and seed production. Three different size groups of sevenband groupers showing 300~400g, 1,500~2,000g and 2,500~4,000g, were collected from June to August, 1996. They were treated two or three times with HCG (500~1,000 IU/kg). Gonadal development of the sevenband groupers were examined using the paraffin section method and then stained with haematoxylin and eosin. When smaller groups of sevenband grouper having 300~400g, 1,500~2,00g and 2,500~3,200g in weight were treated two or three time with HCG 9500~1,000 IU/g), their gonads contained oogonia, oocytes with the size of 20~30${\mu}{\textrm}{m}$, and stroma tissues. However, in case of two HCG treatments with a dosage of 1,000 IU/kg on sevenband groupers of 3,400~4,000g, both healthy eggs of $800\mu$m in diameter and regressing eggs were ovulated. A sevenband grouper of 4,000g obvulated 4,252 eggs in total. Of these, healthy and regressing eggs turned out to be 20.8% and 79.2%, respectively. In addition, previtellogenic oocytes of around $50\mu$m, oocytes of 20~$30\mu$m, and ovulation trace were also observed in the gonad.

• Fisheries and Aquatic Sciences
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• v.14 no.1
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• pp.11-15
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• 2011

We examined the effects of 17${\alpha}$-methyltestosterone (MT) on growth and induced sex change in the longtooth grouper Epinephelus bruneus. The growth rate for body weight (GRW) and specific growth rate (SGR) of the group injected with MT over 8 weeks were significantly higher than those of the sham-injected control group, the group injected over 4 weeks, and the control group. Of the orally administrated groups, the GRWs of the control group and the group given 1 kg of feed with 2.0 mg of MT were highest and did not significantly differ from one another. For SGR, the treatment groups differed significantly, and the SGR of the control group was higher than those of the other groups (P<0.05). The condition factor (CF) of the group injected over 4 weeks was higher than those injected over 8 weeks, the sham-injected control group over 8 weeks, and the control group. The CF did not significantly differ between the sham-injected control group over 8 weeks and the injected group over 8 weeks, but these two groups differed from the control group (P<0.05). The CFs of the groups given 1 kg of feed with 0.5, 1.0, and 2.0 mg of MT were significantly higher than that of the control group (P<0.05). The feed efficiency ratio was not significantly affected by MT administration. Most of the experimental groups receiving MT developed many unidentified germ cell cysts and perinucleolus oocytes, although neither spermazoa cells nor sex-changed males were observed in any of the treatments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.1
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• pp.17-24
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• 2012

We cloned and sequenced the cDNA encoding the $FSH{\beta}$ and $LH{\beta}$ subunits from the pituitary of the blacktip grouper Epinephelus fasciatus, which regulate vitellogenesis and maturation in vertebrates, to achieve stable and healthy gametes. The full-length cDNAs of $FSH{\beta}$ and $LH{\beta}$ were 571 bp and 617 bp, encoding 120 amino acid (aa) and 147 aa proteins, respectively. The deduced amino acid sequences of $FSH{\beta}$ and $LH{\beta}$ were highly homologous (68-97%) to those of other Perciformes; E. bruneus, Dicentrarchus labrax, Thunnus thynnus, and Pseudolabrus sieboldi. Phylogenetic analysis showed that the deduced $FSH{\beta}$ and $LH{\beta}$ amino acid sequences were categorized as a distinct subunit in the $GTH{\beta}$ family, and are closely related to the teleostei $FSH{\beta}$ and $LH{\beta}$, respectively. $FSH{\beta}$ and $LH{\beta}$ mRNA exhibited high abundance in the pituitary gland and low in other brain areas, but were not present in peripheral tissues, as determined by RT-PCR.