• Animal cells and systems
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• 제11권2호
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• pp.117-124
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• 2007

The present study demonstrates the changes in body weight (BW) and plasma sex steroid hormone profiles during artificial maturation induced by human chorionic gonadotropin (HCG) or salmon pituitary extract (SPE) injections in cultured eel, Anguilla japonica, kept in seawater for 3 months. In the weekly SPE-injected female group, BW was relatively stable during vitellogenesis. Following induction of vitellogenesis, females exhibited a rapid increase of BW, and the oocytes were observed to be in the migratory nucleus stage at the end of the experiment. Plasma testosterone (T) and $estradiol-17{\beta}$ ($E_2$) levels increased slightly during vitellogenesis and peaked at an average of 5.82 ng/mL and 4.76 ng/mL, respectively, at the end of the experiment. In the weekly control and HCG-injected female groups, BW slowly decreased during the experimental period, and the oocytes of the two groups were observed to be at the primary yolk globule stage. In the weekly HCG-injected female group, plasma T and $E_2$ levels increased slightly during vitellogenesis and decreased afterward. In the control female group, however, plasma T and $E_2$ levels were not altered during the experimental period. Furthermore, plasma $17{\alpha},20{\beta}-dihydroxy-4-pregnen-3-one$ (DHP) was not detected in all experimental groups. Fertility and hatching rates of SPE-injected females were significantly higher in those that ovulated 15 h after DHP injection than 18 h. These results indicate that long rearing in seawater increases responsiveness to SPE in ovarian maturation of the Japanese eel, resulting in shortened period from completion of vitellogenesis by sex steroid hormone production.

• 한국수산과학회지
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• 제44권3호
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• pp.237-242
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• 2011

To evaluate the proximate composition and main nutritive ingredients (vitamin A, $V_A$; vitamin E, $V_E$; cholesterol; the composition of fatty acids) between eels cultured in different domestic eel farms, we analyzed edible parts of eels that were cultured in three "Water Recirculation System (WRS)" farms and three "Still-Water System (SWS)" farms. We found differences in crude protein, crude lipids and the ash content of eel meat between the farms, but water content showed no significant difference. $V_A$ and $V_E$ contents did not show meaningful differences between the two culture methods, but there was a noticeable distinction between the eel farms. In particular, $V_E$ content showed significant differences between the eels of each farm (highest farm, about 25 mg/100 g dry wt; lowest farm, about 1 mg/100 g dry wt). The fatty acids of cultured eels were composed of monoenes (MUFA, 55-60%), saturates (SFA, 30-33%), $\omega$-6 highly unsaturates (HUFA, 1.6-2%) and $\omega$-3 HUFA (8-9.2%). The MUFA content of WRS eels ($59.9{\pm}1.97%$) was higher than that of SWS eels ($55.8{\pm}0.48%$). The contents of other fatty acids were higher in SWS eels (SFA, $33.0{\pm}0.52%$; $\omega$-6FUFA, $1.98{\pm}0.2%$; $\omega$-3 HUFA, $9.2{\pm}0.67%$) than in WRS eels (SFA, $30.5{\pm}1.34%$; $\omega$-6 HUFA, $1.62{\pm}0.19%$; $\omega$-3 HUFA, $8.0{\pm}0.5%$).

• Fisheries and Aquatic Sciences
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• 제25권1호
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• pp.12-19
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• 2022

In the present study, we investigated the effects of recombinant eel gonadotropins (rec-GTHs) on maturation induction in immature ovarian culture in vitro and sex steroid hormones in vivo in the Japanese eel Anguilla japonica. To study the in vitro effects of rec-GTHs on estradiol-17β (E2) production in immature ovarian tissues, ovarian tissues were incubated with different doses of rec-follicle-stimulating hormone (rec-FSH) or rec-luteinizing hormone (rec-LH). The results revealed that the E2 levels in the rec-FSH (0.1, 0.5, or 1 ㎍/mL)- and rec-LH (0.1 or 0.5 ㎍/mL)-treated groups were significantly higher than those in the female eels from the control group. Furthermore, to investigate the in vivo effects of rec-GTHs on the gonadosomatic index (GSI) and plasma sex steroid hormone levels, the eels were injected intraperitoneally with eel's ringer (control), salmon pituitary extract (SPE; for female eels), human chorionic gonadotropin (hCG; for male eels), rec-FSH, rec-LH, and rec-FSH + rec-LH once a week. The results revealed that except for the SPE and the hCG groups, none of the groups exhibited a significant difference in GSI values. However, in vivo plasma E2 levels increased at the end of 4 weeks after rec-FSH treatment in female eels. Based on these results, it is suggested that rec-GTHs may have a positive effect on sexual maturation in female eels; however, further studies on complementary rec-protein production systems and additional glycosylation of rec-hormones are needed to elucidate hormone bioactivity in vivo and in vitro.

• 한국수산과학회지
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• 제56권4호
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• pp.401-410
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• 2023

This study examined the characteristics of eel Anguilla japonica sperm using the CASA (computer-assisted sperm analysis) system and attempted to provide the composition for artificial seminal plasma by regulating of inorganic elements. Sperm samples were first divided into four groups based on motility and progressive motility: (A) 0-10%, (B) 10-40%, (C) 40-70%, and (D) 70-100%. For observing sperm velocity variations, VCL, which is curve motion velocity, showed the highest values in all groups. The directional factor, beat cross frequency, was lower in higher activity groups, showing an opposite correlation with sperm activity. The head sizes of spermatozoa in higher activity groups were significantly larger than those in lower activity groups. The Na⁺ and K⁺ ions were important in the inorganic composition of seminal plasma in this species. Furthermore, regulating the composition in artificial seminal plasma improved the formula compared to the existing element, exhibiting 120 mM Na and 30 mM K when the sperm was conserved for a long time and 120 mM NA and 40 mM K when the sperm was conserved for a short time.

• 한국수산과학회지
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• 제56권5호
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• pp.634-643
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• 2023

The effects of dietary supplementation with fermented blood meal (FBM) in two forms were evaluated on the growth performance, hematological parameters, innate immune response, antioxidant capacity, digestive enzyme activity and intestinal histology of Japanese eel Anguilla japonica. A commercial powder feed was used as a basal diet (Con). Six other diets were prepared by supplementing 2, 4 and 6% FBM either in powder or liquid form to the Con diet (designated as P2, P4, P6, L2, L4 and L6, respectively). In total 420 eels (initial mean body weight: 55.1±1.71 g) were distributed into 21 tanks (450L) at a density of 20 eels per tank. Three replicate groups of fish were fed one of the seven diets twice daily for 12 weeks. No significant differences were observed in the growth performance and survival among all groups. Fish fed FBM-containing diets showed significantly improved hematological parameters, innate immunity and antioxidant capacity than those in the Con group. Fish fed FBM-containing diets showed significantly enhanced digestive enzyme activity, villus length and goblet cells than those in fish fed Con diet. These results indicate that both powder and liquid FBM could be a good functional feed additive to improve innate immunity and digestion in Japanese eel.

• Fisheries and Aquatic Sciences
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• 제12권4호
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• pp.265-275
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• 2009

G Protein-coupled receptors (GPCRs) mediating wide ranges of physiological responses is one of the most attractive targets for drug development. Rhodopsin, a dim-light photoreceptor, has been extensively used as a model system for structural and functional study of GPCRs. Fish have rhodopsin finely-tuned to their habitats where the intensity and the wavelength of lights are changed depending on its water-depth. To study the detailed molecular characteristics of GPCR architecture and to understand the fishery light-sensing system, genes encoding rod opsins were isolated from fishes living under different photic environments. Full-length rod opsin genes were obtained by combination of PCR amplification and DNA walking strategy of genomic DNA isolated from olive flounder, P. olivaceus, Japanese eel, A. japonica, and Common carp C. carpio. Deduced amino acid sequences showed a typical feature of rod opsins including the sites for Schiffs base formation (Lys296) and its counter ion (Glu113), disulfide formation (Cys110 and Cys187), and palmitoylation (Cys322 and Cys323) although Cys322 is replaced by Phe in Japanese eel. Comparison of opsins by amino acid sequence alignment indicated the closest similarity between P. olivaceus and H. hippoglossus (94%), A. japonica and A. anguilla (98%), and C. carpio and C. auratus (95%), respectively.

• 환경생물
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• 제22권3호
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• pp.446-455
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• 2004

2002년 4월부터 10월까지 홍천강의 어류상 및 어류군집을 조사한 결과는 다음과 같다. 조사된 어종은 모두 11과 52종이었다. 한국고유종은 Rhodeus uyekii, Acheilognathus signifer, A. yamatsutae, Coreoleuciscus splendidus, Koreocobitis rotundicaudata, Silurus microdorsalis 등 23종(44.23%)이었다. 우점종은 Zacco platypus (20.38%), 아우점종은 Z. temmincki (19.62%)였고, 우세종은 Rhynchocypris oxycephalus (8.45%), Pungtungia herzi (8.01%), C. splendidus (6.63%)등 이었다. 홍천강에서 확인된 도입종은 Carassius cuvieri, Lepomis macrochirus, Micropterus salmoides, Anguilla japonica, Gymnogobius urotaenia, Rhinogobius giurinus 등 6종이었다. 이 중 C. cuvieri, L. macrochirus, M. salmoides는 국외종이며 A. japonica, G. urotaenia, R. griurinus는 국내 다른 하천으로부터 도입된 종이다. 어류의 분포에 따라, 홍천강의 어류군집은 주성분 분석(PCA)에 의해 4개의 군집으로 나누어졌다.

• 생명과학회지
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• 제23권12호
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• pp.1454-1459
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• 2013

본 연구에서는 양식산 극동산 뱀장어, Anguilla japonica, 에서 고비율로 암컷 친어를 확보할 목적으로 실뱀장어(평균 전장: 6.5 cm)를 estradiol-17${\beta}$ (E2) 투여구와 일반사료(E2-free) 투여구로 나누어 사육수온 별(20, 24 및 $28^{\circ}C$) 조건에서 4개월간 사육하여 성비조사와 성장변화를 실시하였다. 조사한 결과 본 연구에서 설정한 수온 영역에서는 E2-free 실험구에서는 암컷 비율의 변화가 없었으나, E2 경구투여에 의한 자성화율은 높은 수온($28^{\circ}C$)에서 소폭 증가하였다. 특히, 수온 $24^{\circ}C$ 실험구에서 E2 경구투여 개체가 E2-free 개체보다 성장곡선이 낮게 나타났으며, 혈중 E2 농도는 E2 투여를 종결한 후(178일)에도 여전히 유의적으로 높게 존재하였다. 따라서 E2 투여에 의한 자성화 유도 효과는 높았지만, 장기간 투여시 성장저하에 영향을 미치는 것으로 보인다. 극동산 뱀장어에서 사육조건 중 수온에 의한 암컷으로의 성분화 효과는 확인 할 수 없었으며, 다른 환경인자(사육 밀도, 염분 등)의 관련성도 이후 검토하여야 할 것이다.

• 한국어병학회지
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• 제20권3호
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• pp.315-325
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• 2007

뱀장어, Anguilla japonica (평균체중 96±3.6 g)를 포르말린 0 (대조구), 100, 200, 300, 400 및 500 ppm의 농도로 설정한 사육수조에서 약욕하면서 1시간, 6시간 및 24시간 경과 시 각 농도별 아가미와 간에 대한 병리조직학적 변화를 조사하였다. 아가미에서는 포르말린 200 ppm의 6시간째, 300 ppm의 1시간째, 400 ppm의 1시간째, 500 ppm의 1시간째부터 1차 새변 및 2차 새변의 상피세포 괴사와 박리, 융합, 증생, 비대가 관찰되었다. 한편, 100 ppm의 24시간째는 대조구보다 오히려 1차 새변 및 2차 새변의 상피세포층이 얇아지고 규칙적인 배열을 보였다. 간에서는 포르말린 100 ppm의 24시간, 200 ppm의 24시간, 300 ppm의 6시간, 400ppm의 1시간, 500 ppm의 1시간째부터 간세포의 위축, 핵 농축, 울혈, 세포질 변성이 나타났다. 그러나 100 ppm의 1시간 및 6시간, 200 ppm의 1시간 및 6시간, 300 ppm의 1시간째 약욕한 간은 대조구와 비교하여 특이한 병리학적 조직변성이 관찰되지 않았다.

• 한국어병학회지
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• 제24권3호
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• pp.237-245
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• 2011

2000~2010년까지 감염성질병 발생에 의한 것으로 의심되는 폐사가 발생한 23개소 양식장의 병든 뱀장어를 대상으로 총 29건의 병원체 검사를 실시하였다. 총 7종의 병원체 감염이 확인되었고, 병원체의 감염률은 Pseudodactylogyrus sp. (65.5%, 19/29 시료), aquabirnavirus (ABV, 62.5%, 15/24 시료), Edwardsiella sp. (44%, 11/25 시료), anguillid herpesvirus 1 (AngHV1, 16.7%, 2/12 시료), Heterosporis sp. (10.3%, 3/29 시료), Vibrio sp. (8%, 2/25 시료), Trichodina sp. (3.4%, 1/29 시료) 순으로 높게 나타났다. 병원체의 감염은 단독감염 (44.8%, 13/29 시료) 보다 혼합감염(62.1%, 18/29 시료) 이 높게 나타났으며, 혼합감염의 경우 2~5종의 병원체가 복합적으로 감염되어 있었다. 혼합감염률은 Pseudodactylogyrus sp.-Edwardsiella sp. (10.3%, 3/29 시료), Pseudodactylogyrus sp.-ABV (10.3%, 3/29 시료), Edwardsiella sp.-ABV (6.9%, 2/29 시료) 순으로 높게 나타났다. 기생충, 세균 및 바이러스에 의한 감염은 조사된 대부분의 지역에서 나타났으며, 수온 $25{\sim}30^{\circ}C$ 범위에 사육되고 있는 뱀장어 치어를 비롯한 성어에 이르기까지 무차별적으로 발생하는 것으로 확인되었다.