• Journal of Marine Life Science
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• v.4 no.1
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• pp.38-43
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• 2019

The deformity occurring at the early developmental stage of red spotted grouper (Epinephelus akaara) causes detrimental effects on the process of juvenile production. In this study, we have compared the expressions of several key genes (insulin like growth factor 1: IGF-1, bone morphogenic protein 4: BMP4, peroxisome proliferator-activated receptors γ: PPARγ, matrix Gla protein: MGP) for morphogenesis between normal and 2 types (cephalic and jaw) of deformed juvenile fish. Expression of these genes were investigated in the brain, liver and muscle of each group of fish (n=20) by real-time PCR. Expression of IGF-1 and BMP4 mRNA in the brain and liver showed significant difference between normal and deformed fish (p<0.05). However, no difference was observed in the expression of PPARγ and MGP mRNA between normal and deformed fish in any tissues. It seems certain that IGF-1 and BMP4 are associated with the state of deformity in juvenile red spotted grouper.

• Journal of Life Science
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• v.24 no.9
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• pp.995-1000
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• 2014

The studies of marine viruses in terms of viral isolation and detection have been limited due to the high mutation rate and genetic diversity of marine viruses. Of the modern methods currently used to detect marine viruses, serological methods based on enzyme-linked immunosorbent assay (ELISA) are the most common. They depend largely on the quality of the antibodies and on highly purified suitable antigens. Recently, a new experimental system for using viral capsid protein as an antigen has been developed using the yeast surface display (YSD) technique. In the present study, the capsid protein gene of the red-spotted grouper nervous necrosis virus (RGNNV) was expressed and purified via YSD and HA-tagging systems, respectively. Two regions of the RGNNV capsid protein gene, RGNNV1 and RGNNV2, were individually synthesized and subcloned into a yeast expression vector, pCTCON. The expressions of each RGNNV capsid protein in the Saccharomyces cerevisiae strain EBY100 were indirectly detected by flow cytometry with fluorescently labeled antibodies, while recognizing the C-terminal c-myc tags encoded by the display vector. The expressed RGNNV capsid proteins were isolated from the yeast surface through the cleavage of the disulfide bond between the Aga1 and Aga2 proteins after ${\beta}$-mercaptoethanol treatment, and they were directly detected by Western blot using anti-HA antibody. These results indicated that YSD and HA-tagging systems could be applicable to the expressions and purification of recombinant RGNNV capsid proteins.

• Journal of Aquaculture
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• v.11 no.2
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• pp.173-182
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• 1998

The study has been conducted to understand gonadal development and the effects of $17^{\alpha}$-methyltestosterone on sex inversion of the red spotted grouper, Epinephelus akaara. Fish were collected from Deukyand bay in the southern coast of Korea in August, 1996 and then they had been cultivated at the indoor tank until August, 1997. Gonad somatic index (GSI) in the females of both treated and control group began to increase from February when water temperature was rainse again, and reached the maximum value in August, whereas it had decreased from September adn thereafter maintained relatively low value until January. Unlike females, GSI in the male or intersex of treated groups decreased after June. Hepatosomatic index (HSI) of the control group tended to show the relatively low around Autumn, whereas it showed relatively highr value in April and June when the ovary was in the growing stage. Although the treated groups showed relatively higher value of the HSI than the control, hte paterns in monthly variation of HSI were similar to the control. Sexual change of the female grouper to the male was attempted by acceleration with oral administration of $17^{\alpha}$-methyltestosterone at the dose of 0.2 and 0.5mg/kg fish for 120days. Transitional hermaphroditic gonads were observed from the various size of groupers ranging 21.0 to 36.1 cm in total length, while the functional males could be induced from th individuals of 28.8 to 33.5cm in total length. This result indicated that larger groupers than 30cm in total length should be used for sex inversion to maleness with $17^{\alpha}$-methyltestosterone.

• Journal of fish pathology
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• v.33 no.2
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• pp.103-109
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• 2020

In order to use nervous necrosis virus (NNV) virus-like particles (VLPs) as a delivery tool for heterologous antigens or plasmids, we attempted to produce red-spotted grouper nervous necrosis virus (RGNNV) VLPs displaying a partial region of viral hemorrhagic septicemia virus (VHSV) glycoprotein at the surface and VLPs that are harboring DNA vaccine plasmids within the VLP. A peptide encoding 105 amino acids of VHSV glycoprotein was genetically inserted in the loop region of NNV capsid gene, and VLPs expressing the partial part of VHSV glycoprotein were successfully produced. However, in the transmission electron microscope analysis, the shape and size of the partial VHSV glycoprotein-expressing NNV VLPs were irregular and variable, respectively, indicating that the normal assembly of capsid proteins was inhibited by the relatively long foreign peptide (105 aa) on the loop region. To encapsulate by simultaneous transformation with both NNV capsid gene expressing plasmids and DNA vaccine plasmids (having an eGFP expressing cassette under the CMV promoter), NNV VLPs containing plasmids were produced. The encapsulation of plasmids in the NNV VLPs was demonstrated by PCR and cells exposed to the VLPs encapsulating DNA vaccine plasmids showed fluorescence. These results suggest that the encapsulation of plasmids in NNV VLPs can be done with a simple one-step process, excluding the process of disassembly-reassembly of VLPs, and NNV VLPs can be used as a delivery tool for DNA vaccine vectors.

• Journal of Aquaculture
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• v.11 no.1
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• pp.11-17
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• 1998

Variations of hepatocyte in the larval liver of grouper, Epinephelus akaara wre examined to understand the effect of starvation during the first feeding period, 3 to 5 days after hatching. Total length of the fed larvae increased from the 5th day after hatching, although no significant difference between the fed and starved larvae was found untill the 4th day after hatching. Survival rate of the starved larvae decreased from the 4th day after hatching, and almost all of the larvae died by the 5th day after hatching. Nuclear size of hepatocyte in the starved larvae starterd to decrease from the 4th day after hatching. The sizes by 4th and 5th days after hatching in the starved larvae were 1.4 to 1.9 times smaller than those in the fed ones. Hepatocytes in the starved larvae showed irregular morphology in which the nuclei were irregularly shrunk and highly compacted from the 4th day, while hepatocyte nuclei in the fed ones maintained their uniform features during the whole experimental period. These results implied that the initial larval food should be supplied at least within the 4th day after hatching. Also, it suggested that the size of hepatocyte nucleus might be and indicator of starvation for wild and cultured grouper larvae.