• Animal cells and systems
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• v.13 no.2
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• pp.179-186
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• 2009

Discriminating between eel species of the genus Anguilla using morphological characteristics can be problematic, particularly in the glass eel and elver stages. In this study, sequence-characterized amplified region (SCAR) and polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) markers were developed for the identification of Anguilla japoniea, Anguilla btcoior bicaor. Anguilla rostrata, and Anguilla anguilla. Random amplified polymorphic DNA (RAPD) fragments from A. japoniea (362 bp), A. bicolor bicctor (375 bp), A. rostrata (375 bp), and A. anguilla (375 bp) were isolated, sequenced, and converted to SCAR markers. The principal difference between the SCARs of A. japoniea and the three other species is the absence of a 13 bp deletion in the A. japoniea SCAR. Specific PCR primers amplified a 290 bp fragment for A. japoniea and 303 bp fragments for A. bicolor bicoior. A. rostrata, and A. anguilla. Restriction enzyme digestion with Taql, Mael, and Tru9l yielded PCR-RFLP patterns with differences that, when analyzed together, are sufficient for distinguishing each of the four eel species. In addition, RAPD fragments for A. japoniea (577 bp), A. bicoior bicoor (540 bp), A. rostrata (540 bp), and A. anguilla (509 bp) were also isolated and sequenced. The A. japoniea, A. bicoior blcoior. A. rostrata, and A. anguilla PCR products contain ten, nine, nine, and eight tandem repeats, respectively, of a 37 bp sequence. These results suggest that SCAR and PCR-RFLP markers and repeat numbers for specific loci will be useful for the identification of these four Anguilla eel species.

• Korean Journal of Ichthyology
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• v.12 no.4
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• pp.244-249
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• 2000

This study was conducted to obtain data for identification of species among elvers of anguillids, Anguilla japonica and A. anguilla and A. rostrata implanted in Korea for culture. The longer predorsal length and the fewer number of vertebrae distinguished elvers of A. rostracta from those of A. anguilla and A. japonica. A. japonica and A. anguilla were well discriminated each other in the statistical value of preanal length which the former showed shorter distance. It was remarked phylogenetically that the morphological changes according to growth in head and predorsal length of A. rostrata was different from other two species. So the elvers of A. japonica, A. anguilla and A. rostrata culturing in Korea can be distinguished by the vertebral counts, predorsal and preanal length.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.668-675
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• 2021

The infection status of domestic farmed eels Anguilla japonica, Anguilla bicolor and Anguilla marmorata with Japanese eel endothelial cell-infecting virus (JEECV) and anguillid herpesvirus 1 (AnHV) was examined at the major eel farming areas in Korea. These viruses were detected in all areas examined, regardless of the eel species or age. Any farm with a history of viral infection in adult fish confirmed the infection to be transmitted to stocked fry within 3 to 5 months. It is proposed that both viruses are horizontally transmitted within a given farm. The primary symptoms and histopathological lesions produced by the two viral infections are similar, making it difficult to distinguish the two diseases through clinical symptoms. Both viruses displayed 100% detection in the gills, suggesting that the gills are an optimal tissue for JEECV and AnHV monitoring. This study concluded that JEECV and AnHV were prevalent on eel farms across the country and caused very high mortality when the two viruses co-infected fry. Additional studies, including experimental infections, are needed to clearly understand the pathogenicity of each virus and the risk of co-infection.

• Development and Reproduction
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• v.19 no.3
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• pp.163-166
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• 2015

Genomic DNAs were extracted from the muscle of twenty-one specimens of three eel species collected in Anguilla japonica (AJ), Muraenesox cinereus (MC) and Conger myriaster (CM) from the Yellow Sea, respectively. In the present study, 7 oligonucleotides primers generated 191 specific loci in the AJ species, 226 in the (MC) species and 181 in the CM species, respectively. The primer BION-02 generated the most loci (a total of 83), with an average of 11.86 in the AJ species. The specific loci generated by oligonucleotides primers exhibited inter-individual-specific characteristics, thus revealing DNA polymorphisms. With regard to average bandsharing value (BS) results, individuals from Conger myriaster species (0.808) exhibited higher bandsharing values than did individuals from Muraenesox cinereus species (0.729) (P<0.05). The longest genetic distance (0.430) displaying significant molecular difference was also between individual no. 01 within Anguilla japonica eel species and individual no. 04 within Anguilla japonica species. In this study, the dendrogram resulted from reliable seven oligonucleotides primers, indicating three genetic clusters composed of group I (ANGUILLA 01~ANGUILLA 07), group II (MURAENESOX 08~MURAENESOX 14) and group III (CONGER 15~CONGER 21). The existence of species differentiation and DNA polymorphisms among three eel species were detected by PCR analysis. As mentioned above, a dendrogram revealed close relationships between individual identities within three eel species. High levels of a significant genetic distance among three eel species showed this PCR approach is one of the most suitable tools for individuals and/or species biological DNA studies.

• Journal of Aquaculture
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• v.17 no.4
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• pp.262-267
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• 2004

Physiological responses (oxygen consumption, ammonia excretion, hemoglobin, red blood cell and white blood cell) of cultured eel, Anguilla japonica to vibration stress were studied in an indoor experimental system. Vibration of 76-93 dB (V) from an electric vibrator was provided in 15-minute intervals during daytime (0800-1800) over a ten day period. Oxygen consumption before the beginning of the experiment (0 day) was 83.9 mg $O_2$$.$kg$^{-1}$ ㆍhr$^{-1}$ . After 1, 5 and 10 days of stress respiration rate decreased by 37.5, 53.7 and 70.5%, respectively. Ammonia excretion showed a similar pattern to that of oxygen consumption. Ammonia excretion decreased by 80.1 % following 10 days of vibration stress. Blood hemoglobin concentration also decreased at 1, 3 and 10th day were 29.4% on day 1,83.9% on day 3 and 87.9% by day 10, while red blood cell counts at day 1 and day 10th were 59.8% and 84.7% lower than initial counts, respectively. The white blood cell count increased by 191.2% at day 7, dropping to 41.5% at day 10. Physiological activity was reduced by 50% following 3.4 days of vibration stress.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.860-868
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• 2014

The study was performed to investigate changes in hematological responses and antioxidative enzyme activities (superoxide dismutase, SOD; catalase, CAT) of Japanese eel Anguilla japonica following exposure to 0 (control), 2.33, 4.60, 6,64 and 8.78 mM nitrite-N in fresh water for 48 h. Hematological parameters such as plasma nitrite, electrolytes, cortisol, glucose, glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), hemoglobin (Hb), methemoglobin (metHb) and NADH-methemoglobin reductase (NMR) were measured. Plasma nitrite, cortisol, metHb and NMR increased directly with increasing ambient nitrite concentration, while Hb content showed a progressive decline. Levels of plasma potassium, GOT and GPT of the eel exposed to 6.64 mM ambient nitrite were significantly higher than the control fish. The activity of SOD and CAT in plasma, gill and liver of the eel following exposure to nitrite were augmented by increasing ambient nitrite. Levels of plasma nitrite, metHb, NMR, cortisol, glucose and antioxidative enzyme activities of the eel exposed to 2.33 mM ambient nitrite were significantly higher than the control fish. This study suggested that the eel acutely exposed to elevated ambient nitrite causes nitrite-induced stress responses, changes in antioxidative enzyme activities and hematological parameters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.4
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• pp.193-200
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• 2007

Ion-exchange chromatography and ultra-filtration permeation were used to extract carnosine from the eel Anguilla japonica. In an investigation of its antioxidant properties, the eel carnosine prevented lipid peroxidation in linoleic acid systems, scavenged free radicals, and exhibited superoxide dismutase-like activity. These activities increased as the carnosine concentration increased. The nitrite scavenging effects (NSEs) of commercial carnosine and the eel carnosine were measured at various acidic pHs (1.2, 3.0, and 4.2). For both types of carnosine, the maximum NSE was observed at pH 1.2. At this pH, the NSE of the eel carnosine was 65.3%. Both types of carnosine were effective at maintaining reasonably good color of ground beef patties over 5 days of storage at $4^{\circ}C$ and inhibited metmyoglobin formation as well as lipid peroxidation. These data suggest that the eel carnosine might be useful as a "natural" antioxidant in commercial production and storage of muscle foodstuffs.

• Korean Aquaculture
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• v.19 no.1
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• pp.43-51
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• 2007

말라카이트그린(MG) 및 L-말라카이트그린(LMG)의 소멸은 뱀장어 Anguilla anguilla 유생에서 100일정도 걸린다. 실뱀장어(평균체중: 4.1 g)가 $23.0-26.5^{\circ}C$의 다양한 수온범위에 24시간동안 아주 낮은 농도(0.1 mg/l MG)에 약욕을 실시하였다. 처리한 후 실뱀장어는 말라카이트그린이 없는 깨끗한 물이 들어 있는 수조로 옮겼다. 뱀장어가 수용된 수조에는 순환여과 된 사육수를 공급하였다. 일정한 시간 간격으로 수집된 10마리의 뱀장어 및 사육수의 샘플은 high-performance liquid chromatography (HPLC)으로 분석하였다. 말라카이트그린의 가장 높은 농도는 $435{\pm}59\;{\mu}g/kg(mean{\pm}S.D.)$로서 처리시작 후 6시간에서 나타났다. L-말라카이트그린(LMG) 대사물의 농도는 비교적 높게 나타났으며 ($>100\;{\mu}g/kg$), 처리시작 후 6시간 및 처리종료 후 1500시 사이에서 안정적으로 나타났고 최대농도는 $831{\pm}231\;{\mu}g/kg$이었다. 비록 뱀장어는 체중이 증가하지는 않았지만 노출 후 24시간 후에도 L-말라카이트그린(LMG)은 여전히 전어체 kg당 $15{\pm}12\;{\mu}g/kg$ 함량이 존재하였다. 말라카이트 그린은 처리 이후 1920 및 2400시에서는 발견되지 않았다. 생물적 여과사육수와 순환여과시스템에서는 말라카이트그린이 발견되지 않았다. 본 연구에서는 부가적으로 빠르게 성장하여 11개월 된 뱀장어 두 마리를 샘플하여 분석에 사용하였다. 두 마리의 뱀장어는 실뱀장어기(0.3g)일 때 $0.15\;mg\;l^{-1}$ 농도의 말라카이트그린이 처리되었었다. 뱀장어의 근육조직에서는 지질 크로마토그래피-질량 분광광도계분석에 의해 말라카이트그린과 L-말라카이트그린이 측정 가능한 양으로 함유되지 않음을 확인할 수 있었다($<\;0.2\;{\mu}g\;kg^{-1}$).

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.4
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• pp.1109-1117
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• 2015

Recently, import supply of glass eels from Philippines has been increased in South Korea, and the species distinction was very important to import traders and Anguilla marmorata and A. bicolor pacifica are major species at Philippines. In this study, the species distinction and the rate were researched targeting imported glass eels from the estuaries of North Luzon and the South Mindanao in May and July, 2014. Dorsal fin position and pigmentation pattern at caudal fin are the trait standard for species distinction. The results about morphological identification were coincide with the result of the genetic identification, and the regional distribution of A. marmorata rate was over 90% at North Ruzon in May. However, the rates of A. bicolor pacifica and A. mamorata were 63.3% and 36.7% in May, and were 53.3% and 46.7% in July respectively at South Mindanao.

• Korean Journal of Ichthyology
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• v.29 no.2
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• pp.94-100
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• 2017

Three pseudo-silver eels (PS1~PS3) were found by analysis of silvering index and biological characteristics of 454 eels, Anguilla japonica, collected from the 9 sites of Korean fresh and brackish waters from September 2014 to August 2015. Two specimens (PS1~PS2) from Lake Soyang and one (PS3) from Geum river estuary were identified as pseudo-silver eel showing a large difference between silvering index and GSI. The external morphology of the pseudo-silver eels were in S2 (late silver eel) stage, but they were classified into Y1 (yellow eel) and Y2 (late yellow eel) stage in GSI, Gut index, Eye index and Y2 stage in gonadal development and mean egg diameter.