• Journal of Microbiology and Biotechnology
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• v.25 no.10
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• pp.1761-1767
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• 2015

Sevenband grouper, Epinephelus septemfasciatus, is becoming an important aquaculture species in Korea. However, viral nervous necrosis disease is a large problem causing mass mortality in sevenband grouper aquaculture. Recombinant protein vaccines are one of the best methods to reduce these economic losses. However, the cell-based expression method mainly produces inclusion bodies and requires additional procedures. In this study, we expressed a recombinant viral coat protein of sevenband grouper nervous necrosis virus (NNV) using a cell-free protein synthesis system. The purified recombinant NNV coat protein (rNNV-CP) was injected into sevenband grouper at different doses followed by a NNV challenge. Nonimmunized fish in the first trial (20 μg/fish) began to die 5 days post-challenge and reached 70% cumulative mortality. In contrast, immunized fish also starting dying 5 days postchallenge but lower cumulative mortality (10%) was observed. Cumulative morality in the second trial with different doses (20, 4, and 0.8 μg/fish) was 10%, 40%, and 50%, respectively. These results suggest that rNNV-CP can effectively immunize sevenband grouper depending on the dose administered. This study provides a new approach to develop a recombinant vaccine against NNV infection for sevenband grouper.

• Korean Journal of Ichthyology
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• v.31 no.4
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• pp.235-240
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• 2019

The anaesthetic effect of tricaine methanesulfonate (MS-222) concentrations and water temperatures for longtooth grouper (Epinephelus moara) and hybrid grouper (E. moara ♀ × E. lanceolatus ♂) were investigated. Anesthetic induction and recovery time were measured at 18, 22, 26 and 30℃ of Cwater temperature and 100, 150, 200 and 250 ppm of anesthetic concentrations. Anesthetic induction time tended to decrease with increasing concentration and water temperature. Recovery time was proportional to concentration, but inversely proportional to water temperature. However, there was no significant differences in recovery time at 22℃ or lower. The optimal anesthesia condition was 30℃ and 100 ppm, which was the shortest recovery time for longtooth grouper, and 150 ppm at 30℃ in the case of hybrid grouper because anesthetic time is significantly different with 100 ppm in spite of no significant differences with 100 ppm for recovery time. As a results of two-way ANOVA test, there was a significant difference between the species of longtooth and hybrid grouper. On the other hand, there was no interaction effect between concentration and species. Also, there was no interaction effect among species, concentration, and water temperature.

• Korean Journal of Ichthyology
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• v.31 no.1
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• pp.23-29
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• 2019

The embryonic development and hatchability of the artificially fertilized eggs of convict grouper (Hyporthodus septemfasciatus) ♀${\times}$giant grouper (Epinephelus lanceolatus) ♂ (CGGG) were compared to those of the maternal pure species (convict grouper ♀${\times}$♂, CG) to establish a novel grouper hybrid for aquaculture industry. The fertilized eggs were divided into nine 5-L beakers (3,000~5,000 eggs/beaker) filled with UV sterilized seawater and incubated at a temperature range of $23.5{\sim}24.8^{\circ}C$ (32.1~32.8 psu). The percentages of fertilization and hatching of CGGG were $69.4{\pm}1.5%$ and $59.0{\pm}5.1%$, respectively and were significantly lower than those of CG (p<0.05). The CGGG proceeded normal embryonic development similar to that of CG, but showed an irregular cleavage, immature embryonic body and spinal deformity in hatched larvae. The incubation time from fertilization to hatching of CGGG was 31 hrs, which was approximately 2 hrs slower than that of CG. Our study provided the possibility of mass production of grouper hybrid CGGG larvae.

• Journal of Marine Life Science
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• v.2 no.1
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• pp.1-6
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• 2017

The purpose of this research is to develop the simple freezing method for sperm cryopreservation in the Sevenband grouper and Kelp grouper. The motility and survival rate were checked to investigate the effects of diluent and cryoprotectant on sperm cryopreservation.In cryopreservation experiments, 300 mM glucose and 15% dimethyl sulfoxide (DMSO) were used as a diluent and a cryoprotectant, respectively. As a results of cryopreservation, the motility rate of Sevenband grouper was found to be more than 90%, and that of Kelp grouper was found to be more that 60% in sperm 5 months after cryopreservation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.4
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• pp.391-396
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• 1999

It is well known that fish hear a wide frequency range of sound using both laterial line and inner ear, and the sound is probably the most effective channel for long-range communication underwater than any other stimulus.The auditory threshold of svenband grouper, Epinephelus septem fasciatus was determined by conditioning method using a sound coupled with electric shock in a tank. The audio-signals and electric shock used in the experiment were pure tones of 100 to 1000Hz and DC 6n.The response of fish to the sound was observed by ECG intervals from precordial leads method (V1·V2 method). The auditory threshold curve for sevenband grouper was V-shaped, with most sensitive threshold at 350Hz in the range of 100~1000Hz. The Sevenband grouper were more sensitive to sounds of 200~400Hz than to adjacent frequencies.

• Korean Journal of Ichthyology
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• v.26 no.1
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• pp.70-73
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• 2014

Interspecific hybrids between tiger grouper Epinephelus fuscoguttatus and giant grouper E. lanceolatus were genetically identified based on the partial sequence analysis of mitochondrial cytochrome c oxidase I (COX I) gene and nuclear recombination activating gene 2 (RAG 2) gene. Out of 585 base positions of RAG 2, a total of five nucleotide substitutions were detected between the two parental species (E. fuscoguttatus and E. lanceolatus). The hybrids had two distinct types of RAG 2 sequences corresponding to those of both parental species. Mitochondrial COX I gene sequencing showed that hybrids had sequences identical to E. fuscoguttatus. Molecular data clearly demonstrate that hybridization does occur between E. fuscoguttatus and E. lanceolatus, but with E. fuscoguttatus as the maternal parent.

• Journal of fish pathology
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• v.34 no.1
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• pp.111-115
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• 2021

Immunoglobulin M (IgM) of sevenband grouper (Epinephelus septemfasciatus) was purified by mannan-binding protein (MBP) affinity column. The purified IgM had an apparent molecular weights of 76 (heavy chain) and 28 (light chain) kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Eight hybridoma clones secreting monoclonal antibodies (mAbs) against sevenband grouper IgM were established. Antibody detection enzyme-linked immunosorbent assay (ELISA) with bovine serum albumin (BSA, antigen) and the 8 mAbs revealed that optical density (OD) values were clearly different between sera from BSA-immunization and non-immunization of sevenband grouper. These results suggest that the produced mAbs in this study are specifically reacted with IgM of sevenband grouper.

• Development and Reproduction
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• v.18 no.3
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• pp.127-131
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• 2014

We investigated the androgenic effects of $17{\alpha}$-methyltestosterone (MT) on gonadal sex reversal in juvenile red spotted grouper Epinephelus akaara. The fish were immersed in $17{\alpha}$-MT at 1 and 5 mg/L. Treatment method of $17{\alpha}$-MT was once weekly for 4 and 8 weeks. Fish were sampled at 12 months after end of the treatment period in order to histological analysis. At the initiation of an experiment (70 day after hatching), juvenile red spotted grouper have the paired primordial gonads with somatic cells bellow kidney in the posterior portion of the body cavity. Formation of ovarian cavity indicates that the ovarian differentiation beginning at 70 DAH in red spotted grouper. At 12 months after end of the treatment period, control group, $17{\alpha}$-MT 1 mg/L treatment group for 4 and 8 weeks, and $17{\alpha}$-MT 5 mg/L treatment group for 4 weeks were all female. However, sex-changed males without ovarian cavity were observed in the $17{\alpha}$-MT 5 mg/L treatment group for 8 weeks. In grouper, we firstly reported that the red spotted grouper be able to induce the primary males by hormone treatment prior to gonadal sex differentiation.

• Journal of Microbiology and Biotechnology
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• v.31 no.8
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• pp.1088-1097
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• 2021

Grouper nervous necrosis virus (GNNV) infection causes mass grouper mortality, leading to substantial economic loss in Taiwan. Traditional methods of controlling GNNV infections involve the challenge of controlling disinfectant doses; low doses are ineffective, whereas high doses may cause environmental damage. Identifying potential methods to safely control GNNV infection to prevent viral outbreaks is essential. We engineered a virus-binding bacterium expressing a myxovirus resistance (Mx) protein on its surface for GNNV removal from phosphate-buffered saline (PBS), thus increasing the survival of grouper fin (GF-1) cells. We fused the grouper Mx protein (which recognizes and binds to the coat protein of GNNV) to the C-terminus of outer membrane lipoprotein A (lpp-Mx) and to the N-terminus of a bacterial autotransporter adhesin (Mx-AIDA); these constructs were expressed on the surfaces of Escherichia coli BL21 (BL21/lpp-Mx and BL21/Mx-AIDA). We examined bacterial surface expression capacity and GNNV binding activity through enzyme-linked immunosorbent assay; we also evaluated the GNNV removal efficacy of the bacteria and viral cytotoxicity after bacterial adsorption treatment. Although both constructs were successfully expressed, only BL21/lpp-Mx exhibited GNNV binding activity; BL21/lpp-Mx cells removed GNNV and protected GF-1 cells from GNNV infection more efficiently. Moreover, salinity affected the GNNV removal efficacy of BL21/lpp-Mx. Thus, our GNNV-binding bacterium is an efficient microparticle for removing GNNV from 10‰ brackish water and for preventing GNNV infection in groupers.

• Ocean and Polar Research
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• v.44 no.4
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• pp.365-372
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• 2022

The present study measured the growth performance of juvenile hybrid of red-spotted grouper ♀ × giant grouper ♂ (RGGG) across four water temperatures (19, 23, 27, and 31℃) and compared it to those of maternal purebreds (red-spotted grouper ♀ × ♂, RG) for eight weeks. The specific growth rate (SGR) and weight gain (WG) of RGGG increased as temperature increased, with greater SGR and WG at higher temperatures (27 and 31℃) than RG. The condition factor of RGGG was higher than that of RG and there were no differences between temperature groups within breeding lines. Food consumption increased at higher temperatures for both RGGG and RG, and was the highest in the 31℃ group. Similar to the SGR and WG, the food conversion rate (FCR) in RGGG decreased with increasing water temperature, with the significantly lowest value at 31℃; in RG, however, FCR progressively decreased in the 27℃ group, then increased in the 31℃ group. Furthermore, the FCR of the 31℃ group of RGGG, which had the lowest value among the RGGG groups, was lower than that of the 27℃ group of RG, which had the lowest RG value. In the analysis of nonlinear regression curves within the range of experimental temperature, the optimum temperature for SGR and FCR in RGGG was 31℃, unlike in RG. In conclusion, the growth performance of juvenile RGGG seems to have largely improved from the influence of paternal traits, hybrid with giant grouper, and it is presumed to be more profitable for commercial production in tropics/subtropics.