• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.4
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• pp.418-425
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• 2021

The effects of an aquaponic system based on biofloc technology (BFT-AP) were analyzed for eel Anguilla japonica as aquaculture species and caipira Lactuca sativa as the cultivated crops. The rate of weight gain rate by the eels was 178% (BFT-AP 200 head) > 136% (BFT-AP 100 head) > 100% (BFT). The eel body weight in the BFT-AP (200 head) significantly increased when compared to the BFT only eel group (P<0.05). The weight of the upper layer of caipira was 91±8.5 g (200 head) > 90±8.9 g (100 head) > 48±8.3 g (Hydroponic crop, HP). The crop growth in all BFT-AP groups was higher than the control, the hydroponic group. The total ammonia nitrogen (TAN) and NO₂^--N concentrations decreased in the BFT-AP group when compared to the BFT group. It was possible to remove nitric acid from the aquaponics system and reuse it as eel rearing water. Although some nutrient concentrations were low in BFT when compared to HP, the nutrient concentration was sufficient for plant growth. The results show that BFT has the potentially to provide a sustainable aquaponic system.

• Korean Journal of Ecology and Environment
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• v.52 no.1
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• pp.65-70
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• 2019

A total of 23 individuals of glass eel (Anguilla japonica) were investigated from two estuarine barrages of the Nakdong River in 2016. It was observed that most individuals migrated through the eastern barrage, compared to the western. Individual numbers differed significantly along the corridor modification of the barrages; for example, the number of individuals was two to three times higher after the modification. These results indicate that modification of fish way and lock gate for has facilitated migration of glass eel, and our study potentially offers the operation strategy of estuarine barrage in order to induce more active migration of glass eel.

• Development and Reproduction
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• v.25 no.3
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• pp.133-143
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• 2021

In contrast to the human lutropin receptor (hLHR) and rat LHR (rLHR), very few naturally occurring mutants in other mammalian species have been identified. The present study aimed to delineate the mechanism of signal transduction by three constitutively activating mutants (designated M410T, L469R, and D590Y) and two inactivating mutants (D383N and Y546F) of the eel LHR, known to be naturally occurring in human LHR transmembrane domains. The mutants were constructed and measured cyclic adenosine monophosphate (cAMP) accumulation via homogeneous time-resolved fluorescence assays in Chinese hamster ovary (CHO)-K1 cells. The activating mutant cells expressing eel LHR-M410T, L469R, and D590Y exhibited a 4.0-, 19.1-, and 7.8-fold increase in basal cAMP response without agonist treatment, respectively. However, inactivating mutant cells expressing D417N and Y558F did not completely impaired signal transduction. Specifically, signal transduction in the cells expressing activating mutant L469R was not occurred with a further ligand stimulation, showing that the maximal response exhibited approximately 53% of those of wild type receptor. Our results suggested that the constitutively activating mutants of the eel LHR consistently occurred without agonist treatment. These results provide important information of LHR function in fish and regulation with regard to mutations of highly conserved amino acids in glycoprotein hormone receptors.

• Food Science and Preservation
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• v.30 no.6
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• pp.929-943
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• 2023

This study analyzed the variation in vitamin K content in conger eel (Conger myriaster) caught off Tongyeong, Gyeongsangnam-do, Korea, focusing on the influence of size (large and small) and harvest period (monthly throughout 2021). We applied enzymatic extraction and HPLC-fluorescence methods for the analysis of vitamin K₁ (phylloquinone) and K₂ (menaquinone). The vitamin K content in conger eel varied significantly with size and harvest season (p<0.05). In large-sized samples, the phylloquinone content peaked in July (0.80±0.09 ㎍/100 g), while the highest menaquinone content was in May (0.79±0.11 ㎍/100 g). Conversely, in small-sized conger eels, the highest phylloquinone was found in December (1.94±0.15 ㎍/100 g), and the peak menaquinone level was in January (0.66±0.02 ㎍/100 g). The fat content was highest in July for large samples and in January for smaller ones. There was a positive correlation between fat and total vitamin K contents in conger eel (r=0.631, 0.667). Method validation and quality control measures ensured data reliability for vitamin K₁ and K₂ analyses. This study provides reliable information on the size and seasonal variations of vitamin K in conger eels, a staple in the Korean diet. This information is valuable for inclusion in Korea's national food nutrition database and for formulating future national health and nutrition policies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.60-66
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• 1986

The muscles of wild and cultured eel, Anguilla japonica, were analyzed for the protein composition and amino acid profile. The differences of the subunit distribution for the sarcoplasmic and myofibrillar proteins were discussed with sodium dodecylsulfate(SDS) polyacryamide gel electrophoresis. The muscle protein in wild eel was composed of $30.78\%$ of sarcoplasmic, $59.02\%$ of myofibrillar, $9.73\%$ of residual intracellular and $2.47\%$ of stroma fraction. That in cultured eel was composed of $31.81\%,\;58.37\%,\;8.16\%\;and\;1.80%$, respectively, The sarcoplasmic and myofibrillar proteins were composed of 16 and 14 subunits in wild eel, and 22 and 15 subunts in cured eel. The sarcoplasmic protein between wild and cultured muscles showed a similar trend in the subunits, except a few subunits such as 36,500, 46,000, 58,500, 75,000, 170,000 and 235,000 daltons in cultured eel. Only the existence of 45,000 dalton subunit was the difference between wild and cultured eel in myofibrillar protein. The distribution patterns of total amino acid in muscles of wild and cultured eel were found to be very similar trend, although glycine content in wild eel was slightly higher than that in cultured one.

• Korean Journal of Ichthyology
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• v.12 no.3
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• pp.203-207
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• 2000

The synaphobranchid eel, Dysomma anguillare was redescribed on the basis of a specimen collected from the Yellow Sea, Chollabuk-do, Korea. The D. anguillare was characterized by many fleshy plicae at the front of upper and lower jaws, dorsal fin originated in slight advance than pectoral fin base, degenerated eyes, very short trunk and long tail, anus located below near tip of pectoral fin and no scales.

• Toxicological Research
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• v.13 no.3
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• pp.209-213
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• 1997

Residue and recoveries of clindamycin were investigated by reversed-phase high performance liquid chromatography (RP-HPLC) which was infected for the control of streptcoccal infection in Anguilla japonica and Paralichthys olivaceusis. Detection limit was 0.1 ppm. Recoveries of clindamycin in muscles of flounder and eel were 80.4 and 78.8%, respectively. The clindamycin in eel and flounder was detected up to 13 and 15 days after dosing, respectively.

• Korean Journal of Veterinary Research
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• v.39 no.2
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• pp.365-369
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• 1999

A study on quinolone antibacterial, norfloxacin, was performed to apply for the control of bacterial diseases in eel (Anguilla japonica). Norfloxacin was proved excellent in antibacterial activity and sensitivity against fish bacterial pathogens when compared with the existing antibacterials and antibiotics. And any side effect was not observed during the period of indicated use. An outline of minimal inhibitory concentration was $0.03{\sim}0.1{\mu}g/ml$, $TLm_{48h}$ value was 3,500mg/l. The residual time of the day in fish body was less than 17 days and any pathological changes were not observed. The study has revealed that norfloxacin can be applied to treat some fish bacterial disease by the dosage of 100g/day/ton of fish body weight for about 3 days perorally. Further, norfloxacin may be used for the control of bacterial pathogens in eel.

• Journal of Food Hygiene and Safety
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• v.20 no.2
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• pp.98-102
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• 2005

As a part of basic investigation for utilizing cultured eel and by-products as a food source, a mineral contents and fatty acid composition of bone and flesh were investigated. Flesh of cultured eel was higher in moisture and crude protein content, and lower in crude ash and lipid content than those of the bone. Mineral of bone were measured 220.72 mg/100 g of Ca, 169.87 mg/100 g of P, 117.05 mg/100 g of Na,92.75 mg/100g of K, 6.18 mg/100g of Cu,5.02 mg/100 g of Zn,2.56 mg/100 g of Fe, and flesh were measured 120.23 mg/100g of CL 150.36 mg/100 g of P, 136.36 mg/100 g of Na, 89.36 mg/100 g of K, 4.02 mg/100 g of Cu, 1.71 mg/100 g of Zn,2.03 mg/100 g of Fe. The major fatty acid in bone and flesh of cultured eel were generally oleic acid $(44.40\%, 43.76\%)$, palmitic acid $(24.19\%,\;21.30\%)$, palmitoleic acid $(8.18\%,\;7.72\%)$, eicosapentaenoic acid $(5.72\%,\;6.65\%)$, myristic acid $(3.96\%,4.34\%)$ in order. The fstty acid composition of total lipid was no significant difference among bone and flesh of cultured eel, However, bone of cultured eel revealed higher content in saturated and monounsaturated fatty acid, while lower in polyunsaturated fatty acid than those of the flesh. It is shown that cultured eel contains various nutrients such as protein, minerals, unsaturated fatty acid, so cultured eel can be regarded as a highly nutritious food.

• Journal of Life Science
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• v.24 no.7
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• pp.728-736
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• 2014

The purpose of this study was to improve and strengthen the function of eel extract prepared with 5 brix eel extract (EE), 5 brix eel and plant mix (black garlic, ginseng, black jujube) 0.35 ml extracts prepared and treated with the extract (EIM-1), and 0.7 ml (EIM-2) divided group. The extracts were administered to rats for five weeks during running training, and the lipid profiles and antioxidant enzyme activities were tested. The lipid content in liver and serum were lower than the normal group difference was not significant between groups. Serum total cholesterol was lower in the experimental group than the control group the mixed extract significantly lower level. HDL-cholesterol levels in the eel extract and eel mixed extract significantly increased by feeding the EIM-1 is 2.0 times, EIM-2 is increased by 2.3 times. Liver glycogen content in the experimental group performed the exercise group compared with the normal control group was significantly lower than in EIM is significantly higher than the control group. The TBARS content in the liver and serum was significantly higher than the normal group was lower than the control group. GOT and GPT were significantly decreased compared to the control group. Hepatic catalase activity was significantly increased in the EIM-1 group, and SOD and GSH-px activities were increased in the EIM-1 and EIM-2 groups. Supplementation with the eel and plant mix extract increased the activities of antioxidant enzymes. Thus, intake of the eel and plant mix extract could improve the antioxidant status and combat different types of oxidative stress.