• Journal of Marine Life Science
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• v.7 no.2
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• pp.154-162
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• 2022

In this study, data on the types and density of abalone attached organisms were provided in marine net cage of the southern coast. In addition, the effect of the removal of attached organisms was evaluated. In marine net cage, oysters, bryozoa, and barnacles were dominated among the attached organisms, and their average area ratio was about 57.5%. The growth rate and hepatopancreas condition were better in removal group of attached organisms than control group. Therefore, it is judged that the removal of attached organisms from abalone is necessary for the growth of individuals and improvement of value.

• Journal of Practical Agriculture & Fisheries Research
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• v.16 no.1
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• pp.143-154
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• 2014

Settlement of artificially released abalone, Haliotis discus hannai at the marine farming area in Jeollanam-do in 2007 was very efficient by showing the recapture of 2.0-5.2 ind./m² and the survival rate of 60-67%. The growth of shell after 1 year was highest in Hwoenggando by 75.9 mm and the lowest in Hwasan by 64.6 mm. Our result especially showed that the effect of the stock recruitment was the most efficient when abalone was released. The shell growth of the released abalone was better when sea mustard (Undaria sp.) was provided as food (shell length was up to 23.9 mm) or predators were periodically removed (shell length was up to 23.8 mm) in order to enhance the effect of the artificial release than the control group. The recapture rate was also higher than the control. However due to the difficulty of managing the release areas, it will be more efficient to release the recruited stocks after considering various biological and ecological factors such as survey of suitable release areas, stock size, release density, and health of stocks.

• The Korean Journal of Malacology
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• v.30 no.4
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• pp.415-419
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• 2014

Inbreeding depression may be an avoidable phenomenon for abalone culture. However, only a few studies were carried out on inbreeding depression. In the present study, to demonstrate inbreeding depression in growth trait of Pacific abalone, H. discus hannai, inbreeding and outbreeding families were produced in 2010. Inbred and outbred families from each experiment were reared in same tank until 10 month for the same breed environment. The individual of inbred and outbred were distinguished by paternity test using microsatellite DNA. The shell length between inbred and outbred families was compared. At the results, significantly higher shell length was observed in the outbred families at 10 mon (P < 0.05). These results indicate that inbreeding depression is obviously observed in growth traits in the first generation of full-sib family of the H. discus hannai.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.197-205
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• 2013

Even though seedling production of Haliotis discus hannai has fully developed, the culture of benthic diatom as a live food for larvae is still a barrier to solve in commercial hatchery. The farmer depends on mixed microalgae which are non-selectively attached on the plate by flowing of natural seawater. The adequate diatom on the plate for the larvae in terms of quality and quantity is always significant bottleneck in the hatchery. In this study, two benthic diatom species, Caloneis schroederi and Rhaphoneis sp. were separately cultured in mass and inoculated to four tons' settlement tank of the larvae. And the larvae and the spats were cultured for nineteen and nine weeks, respectively. The result on seedling production of H. discus hannai with this method was compared to that of the farmer's traditional method as a control. With regard to variation of species composition of benthic diatom on the plate, C. schroederi and Rhaphoneis sp. were dominant for first three weeks after inoculation. But the diverse diatoms mainly, Navicula, Amphora, Cylindrotheca, Licmophora, Pleurosigma began to attache on the plate from the 4th week. The larvae attached 2.5 times more in C. schroederi tank than in the control tank. The final total biomass of the seeds in Rhaphoneis sp. tank was 3.2 times more than that of the control tank. The retared-spats in the seedling production also showed significantly higher growth and survival in the spat fed Rhaphoneis sp. or C. schroederi than those in the control group. We suggest that C. schroederi is proper for settlement of the larvae and Rhaphoneis sp. is appropriate for the growth of the larvae and spats in the commercial hatchery of H. discus hannai.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.317-322
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• 2011

This study was performed to obtain the basic data on physiological responses of low water temperature stress of the cultured Pacific abalone, Haliotis discus hannai. Abalones were exposed at low water temperatures of $7^{\circ}C$ and $4^{\circ}C$. We have investigated survival rate, superoxide dismutase (SOD) activity and total protein (TP) in the abalone by the exposure times (0, 3, 6, 12, 24, 72, 120, 168 and 216 hours). Survival rate of the abalone at $7^{\circ}C$ experiment was 90.8%, whereas at $4^{\circ}C$ experiment was 0% after exposure 10 days. SOD activity was significantly increased until 12 hours after exposure to $4^{\circ}C$, and then was recovered to starting level after 24 hours. However, there was no significant difference between control ($12^{\circ}C$) and $7^{\circ}C$ experiments. TP was significantly increased until 216 hours after 24 hours at $4^{\circ}C$ experiment, but $7^{\circ}C$ experiment showed no significant differences compared to control ($12^{\circ}C$) experiment. Therefore, H. discus hannai was acclimated in low water temperature stress at $7^{\circ}C$, but at $4^{\circ}C$, all abalone died possibly because they exceed the limits of defense ability to too low temperature.

• Journal of Aquaculture
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• v.18 no.1
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• pp.7-12
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• 2005

This study was conducted to investigate antioxidant enzyme activity (catalase and superoxide dismutase) and Heat Shock Protein 70 (HSP70) mRNA variation in hepatopancreas of abalone (Haliotis discus hannai) cultured under several acute water temperatures. Abalones were cultured at 10, 15, 20, 25 and $30^{\circ}C$, for 0, 6, 12, 24 and 48 hours, respectively. The HSP70 mRNA expression in hepatopancreas was more increased at $30^{\circ}C$ compared to those at 10. 15, 20 (control) and $25^{\circ}C$. The superoxide dismutase (SOD) activity was increased in hepato-pancreas at all water temperature conditions compared to the control ($20^{\circ}C$). The SOD activity at high water temperature (25 and $30^{\circ}C$) tended to be increased after 12 hours, and was increased immediately after exposure to low water temperature (10 and $15^{\circ}C$). and then was recovered to starting level after the increase. Also, catalase (CAT) activity in hepatopancreas was increased in all the groups except for at $10^{\circ}C$ than the control ($20^{\circ}C$). Survival rate of abalone was $100\%$ at 10, 15, 20 and $25^{\circ}C$, but $92\%$ at $30^{\circ}C$. Thus, according to our study, when abalone is appeared at $20^{\circ}C$, defense mechanism against stress at low water temperature can be accelerated to be stabilized at about $5^{\circ}C$. In the case of exposure of abalone to high water temperature, antioxidant enzyme and HSP70 expression were increased due to elevated physiological stimulation factor, such as temperature.

• The Korean Journal of Malacology
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• v.30 no.3
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• pp.243-248
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• 2014

This study histologically describes the gonadal development and reproductive cycle of the abalone, Haliotis discus hannai inhabiting Jindo on the southern seashores of Korea. Gonads displayed histologically definitive seasonal changes. The female ratio (F/F + M) was 57% (n = 154/271). The gonad index (GI) of both males and females was the highest (3.3 and 3.9) in June and was the lowest (1.1 and 1.1) in December. The condition index (CI) and meat weight rate (MWR) were highest in May and lowest in October. The pattern of changes in the GI, CI and MWR were similar to the pattern of seasonal changes in gonadal tissues. The reproductive cycle was divided into an inactive stage (November-December), early active stage (January-March), late active stage (March-April), ripe stage (May-June) and spent and degenerative stage (July-October). The main spawning period of Haliotis discus hannai was July to August at Jindo in 2013.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.225-232
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• 2013

This study looked into recovery rate and histological changes in the gills of juvenile abalone Haliotis discus hannai by exposure time (3, 6, 12, 24 and 48 h) of different water temperatures (15, 20 and $25^{\circ}C$) and salinities (30, 25, 20 and 15 psu) to understand reasons for the death of abalone exposed by low salinity water. In each water temperature, abalone spats that were exposed to low salinity water (less than 20 psu) for over 6 hours showed decrease in survival rate during recovery and those were exposed at the salinity of 15 psu for more than 24 hours all died. Histological observation showed expansion or damage of gills of the species which were exposed at less than 20 psu for over 6 hours. In case of abalones exposed at the salinity of 15 psu for over 24 hours, most gill tissues were destroyed. This result was glaringly obvious at a higher water temperature, lower salinity and longer exposure time. Accordingly, suffocation caused by damage of gills considered one of direct causes of the death.

• Journal of Marine Life Science
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• v.7 no.1
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• pp.15-20
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• 2022

Glioblastoma is one of the highly aggressive central nervous system tumors and it is difficult to treat owing its anatomical location. Peptides are novel class of drugs which has the potential to cross the blood brain barrier and exerts its anti-tumor activity. Here, we discovered a novel peptide from abalone (Haliotis discus hannai) next generation sequencing (NGS) data and tested its anticancer effect on glioblastoma cell line SNU-489. The anticancer activity was measured using a cytotoxicity assay in a time and dose-dependent manner. A concentration and time dependent increase in the cytotoxicity was seen in cells treated with the novel peptide. The highest cytotoxicity rate of about 67% was observed in SNU-489 cells treated with 200 µM peptide for 48 hrs. However, the cytotoxic effect was not or less observed in a normal skin cell line HaCaT at similar concentration, thus, evident of peptide's cell specific anticancer activity. In addition, the gene expression level of necroptosis-related genes was analyzed by qRT-PCR to elucidate the anticancer mechanism of the novel peptide. RIPK3 expression was significantly increased by 9.6-fold in 200 µM of novel peptide treatment group, and MLKL expression level was significantly elevated by 2-fold in 100 µM treated group compared to the control group. Therefore, this study confirmed that the novel abalone-derived peptide has anticancer potency, and it causes cancer cell death through the necroptosis mechanism. Collectively, these results suggest that the novel peptide could be candidate anticancer agent for the treatment of glioblastoma in the future.

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.281-282
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• 2006