Tesis: "Anguilla japonica Eels"

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Tsoi, Chang-ming Stephen. "Biochemical and molecular studies of Lactate Dehydrogenase Isozymes in the freshwater eels, anguilla japonica (Temminck & Schlegel) and Anguilla rostrata (Le Sueur) /." [Hong Kong] : University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13637563.

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Lee, Wai Sin. "Effects of exogenous cortisol on the expression of cortisol and natriuretic peptide B receptors mRNA in gill epithelia of Japanese eels, Anguilla japonica." HKBU Institutional Repository, 2003. http://repository.hkbu.edu.hk/etd_ra/418.

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9

Ho, Cheuk Hin. "Effects of osmotic stress on molecular responses of gill cells from Japanese eels, Anguilla Japonica." HKBU Institutional Repository, 2021. https://repository.hkbu.edu.hk/etd_oa/885.

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Japanese eels (Anguilla japonicas) are snakelike fishes living in waters in the Asian region. In contrast to most fishes which are stenohalines that can only live in waters with a narrow range of salinity, Japanese eels are classified as euryhalines that can habitat in a broad range of salinity. As the lifecycle of Japanese eels consists of stages across fresh and seawater districts, a well-developed osmoregulation mechanism is needed to balance the intra- and extra- cellular osmolarity of the fishes throughout the seawater acclimation process. While fish gills are one of the organs that separating the ambient water and the inner body fluid of the fish, the fish gills of the Japanese eels have been studied as one of the most crucial organs for osmoregulation purposes. Yet, the osmoregulation and survival strategies of Japanese eels under hyperosmotic stress has not been fully elucidated. In chapter 2, this study has performed a transcriptome study on the ex vivo gill filament model of the Japanese eel to profile the molecular responses after a hypertonic treatment of 4 hours or 8 hours. The experiment is aimed to mimic the gill cells exposed to seawater in the seawater acclimation process of Japanese eels. A profile of differential expressed genes (DEGs) has been revealed that 577 DEGs were commonly upregulated and 711 DEGs were commonly downregulated in both 4- and 8-hours hypertonic treatment. Functional analysis and annotation have been processed with these DEGs, including Ingenuity Canonical Pathways analysis and gene ontology. These analyses have revealed that the cellular homeostasis of the gill cells has been disrupted and cell death responses has been induced by osmotic stress. The results have raises a concern that the maintenance of cellular viability and a cell death regulation mechanism are needed for the fishes to survive in the early stage of seawater acclimation. In chapter 3, this chapter demonstrated that gill cells in Japanese eels are susceptible to apoptosis when they are exposed to hyperosmotic treatments in both in vitro gill cell and the ex vivo gill filament model. To maintain the viability of the gills cells, two inhibitors of apoptosis, XIAP, and survivin, were seen to be expressed in gills cells. The expression of XIAP and survivin were upregulated by dexamethasone, which is an agonist mimicking the effect of cortisol on fishes in seawater acclimation. Meanwhile, the expression levels of the apoptosis executor, caspase 3, were downregulated. These data suggested that with the regulation of cortisol express in the fishes, XIAP and survivin are effective apoptosis regulators in the gill cells of Japanese eels. The study has demonstrated the molecular responses of the gills of Japanese eels exposed to hyperosmotic stress at the transcriptional level and post-translational level by using transcriptome studies and protein study respectively. The study has paved cell death regulation to be another the key field to study in understanding the ability of salinity tolerance in euryhalines.

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Bracamonte, Seraina Emilia. "Immune and metabolic processes jointly contribute to susceptibility to invasive parasites - The case of Anguillicola crassus in eels." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21074.

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Die Einschleppung gebietsfremder Parasiten durch den Menschen ist einer der Hauptgründe für das Auftreten neuer Krankheiten in the letzten Jahrzehnten. Neue Wirte sind oftmals anfälliger für diese invasiven Parasiten als die ursprünglichen Wirte. In schwerwiegenden Fällen können invasive Parasiten zu Massensterben und zum Aussterben ihrer neuen Wirte führen. Der ursprüngliche Wirt des Aalparasiten Anguillicola crassus ist der Japanische Aal. In den frühen 1980er Jahren wurde der Parasit in die Population des Europäischen Aals eingeschleppt. Er ist einer der Faktoren, die für den Populationsrückgang des Europäischen Aals verantwortlich sind. Die molekularen Prozesse, die zur stärkeren Anfälligkeit des Europäischen Aals im Vergleich zum Japanischen Aal führen, sind noch nicht zureichend bekannt. Die Analyse transkriptomweiter differenzieller Genexpression von Immungewebe ergab, dass im Europäischen Aal sowohl Immun- als auch Nichtimmungene differenziell exprimiert waren. Dies war im Japanischen Aal nicht der Fall und deutet darauf hin, dass der Europäische Aal eine ineffiziente und kostspielige Immunantwort auslöst. Die Resultate ensprechen jenen die schon in anderen Wirbeltierwirt-invasiven Parasiten-Systemen beobachtet wurden. Ausserdem stützen diese Resultate die Hypothese, dass neuen Wirten eine wirksame Immunantwort fehlt und sie deuten darauf hin, dass Nichtimmunprozesse wesentlich zur höheren Anfälligkeit von neuen Wirten beitragen. Als Reaktion of die negativen Fitnesseffekte können neue Wirte Abwehrmechanismen entwickeln. Im Europäischen Aal entspricht das der Einkapselung von A. crassus. Einkapselung führte zu eine niedrigere Abundanz adulter A. crassus. Dies deutet darauf hin, dass das Einkapseln sich positiv auf die Gesundheit infizierter Aale auswirkt. Jedoch war die Abundanz zweier nativer Parasiten höher in Aalen, die A. crassus einkapselten. Eine verbesserte Abwehr des eingeschleppten Parasiten könnte daher die Abwehr nativer Parasiten beeinträchtigen. The human-mediated translocation of non-native parasites into foreign regions is one of the primary factors for the emergence of new diseases in recent decades. Novel hosts are often more susceptible to these invasive parasites than the native host. In severe cases, invasive parasites can lead to population declines and extinctions of their novel hosts. The eel parasite Anguillicola crassus is native to the Japanese eel. In the early 1980s it was introduced into the European eel population and is now considered to be one factor contributing to the population decline of its novel host. The underlying molecular processes determining higher susceptibility in the European eel compared to the Japanese eel are not well understood. Using whole-transcriptome differential gene expression analysis of immune organs, I found that genes involved in both immune and non-immune processes were differentially expressed in the European eel but not the Japanese eel, suggestive of an ineffective and costly immune response in the former. These results are in line with those observed between susceptible and resistant hosts in other vertebrate host-invasive parasite systems. Furthermore, the results support the hypothesis that novel hosts lack an effective immune response. The results also suggest that alteration of non-immune processes contributes substantially higher susceptibilities of novel hosts. In response to the negative fitness effects of invasive parasites, novel hosts can evolve coping mechanisms. The European eel has the capacity to encapsulate and kill A. crassus. Using natural infections, I found a lower abundance of adult A. crassus, the most costly parasitic stage in those eels encapsulating the parasite, suggesting that encapsulation can potentially improve health of infected eels. At the same time, the abundance of two native parasites was higher in those eels encapsulating A. crassus. Thus, coping with A. crassus may come at the expense of coping with native parasites.

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Chow, Sheung Ching. "The characterization of hyperosomotic stress-induced signaling cascades and the downstream effectors in primary gill cell culture of Japanese eels, Anguilla japonica." HKBU Institutional Repository, 2010. http://repository.hkbu.edu.hk/etd_ra/1182.

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Alisa, Kutzer. "Trophic ecology of Japanese eels （Anguilla japonica） in river habitats with implications for the conservation of an endangered species." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263812.

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Wong, Kong-chu. "Functional and morphometric study of the isolated chloride cell and respiratory cell from the gill epithelium of the Japanese eel, Anguilla Japonica (Temminck & Schlegel) /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19667991.

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Yu, Mei-kuen. "The chloride cell of the gill epithelium of Japanese eel, Anguilla japonica : adaptation in response to salinity change /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22054704.

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余美娟 and Mei-kuen Yu. "The chloride cell of the gill epithelium of Japanese eel, Anguilla japonica: adaptation in response to salinitychange." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31223862.

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黃港住 and Kong-chu Wong. "Functional and morphometric study of the isolated chloride cell and respiratory cell from the gill epithelium of the Japanese eel,Anguilla Japonica (Temminck & Schlegel)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31235414.

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蘇孫漢 and Shun-han Henry So. "Studies on morphological and biochemical changes of epithelial cells of the gill of the Japanese eel, Anguilla japonica (Temminck &Schlegel), in response to chronic pH changes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31223382.

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So, Shun-han Henry. "Studies on morphological and biochemical changes of epithelial cells of the gill of the Japanese eel, Anguilla japonica (Temminck & Schlegel), in response to chronic pH changes /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21687717.

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Wong, On-Lam Anderson. "Short term and long term physio-biochemical adaptations of the Japanese eel (Anguilla Japonica, Temminck & Schlegel) to temperaturechanges." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B31209014.

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Cheng, Heng Jeng, and 鄭恆仲. "Evaluation on the induced maturation of Pacific eels, Anguilla japonica, through endocrinological manipulation." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/60011370557487335034.

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Ng, Wun-Shing, and 吳煥成. "Artificial induction of spermiation and spontaneous spawning in cultivated Japanese eels (Anguilla japonica)." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/41092707790684136779.

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碩士 國立臺灣大學 漁業科學研究所 91 As the quality of mature spawners can affect the success in the synchronous spawning and spermiation, the evaluation of the spawners’ characters becomes prerequisite. In addition to evaluation the extent of gonad maturation of both genders, the advancement of silvering-related changes of the eels under seawater condition was also critically examined. This study aims to follow the same two-step strategy to induce both genders of immature Japanese eels (Anguilla japonica) to fertilize under artificial condition. 　　The cultured Japanese eels with body weight of 564±102 g, were acclimated to seawater for two weeks. Prior to induction, the extent of ovarian growth had attained the cortical alveolar stage of previtello- genesis. Without hormonal induction, the silvering-related changes also advanced after 6 weeks in the seawater. On the contrary, with or without hormonal induction, silvering-related changes did not advance in the fresh water. Therefore, after the first-step induction in the seawater, the silvering- related changes advanced prominently in association with the gonad maturation. The extent of silvering is comparable to the wild migratory ones in fresh water. 　　In the first-step induction, weekly injections of salmon pituitary homogenate (SPH) plus methyl testosterone (MT) were adopted for 6 weeks, and thereafter, replaced by only SPH until the completion of vitellogenesis or spermatogenesis. The SPH plus 17α-hydroxyprogester- one(OHP) were then adopted further for the second-step induction. The spermiation peak lagged behind the vitellogenesis peak for about two weeks. Two thirds of males spermiated for two to four weeks of duration. Intraovarian oocytes could be induced to mature synchronously by SPH plus MT in the first-step. SPH must be adopted throughout in the process of induction because the supplement of SPH to OHP in the second-step improved the occurrence of spontaneous spawning in the females. Further, the synchronous spawning and spermiation was observed in 14 tons pool, timely on the 19th hour after final induction. The fertilization rate was about 60-85 % and the eggs hatched at the 38th hour under 22-23ºC water temperature. As results, this modified two-step method can be applied to induce maturation of both genders initially from immature status of gonad to spontaneous spawning and spermiation. This simplifies and integrates the induction technigue of the eels.

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SHEN, MING-CHENG, and 沈明成. "Studies on spore properties and infectious route of Plistophora anguillarum in eels (anguilla japonica)." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/08783655408970935874.

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Wang, YungSong, and 王永松. "Effects of Pituitary Homogenate and Sex Steroids on the Ovarian Development in Japanese eels, Anguilla japonica." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/83443064569186233409.

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碩士 國立臺灣大學 漁業科學研究所 87 Treatment of Japanese eel with salmon pituitary homogenate (SPH) to induce gonadal development has heen demonstrated, yet still not so effectively. This experiment was designed to examine the effects by exogenous sex steroid and the SPH treatment. Besides control group, silver eels were divided into five treatments of SPH group, and sex steroids (E2 or MT) with or without SPH groups. Eels received weekly intraperitoneal injections SPH and /or sex steroids at 20g and 3mg per kg body weight, respectively. The gonadal development were examined by histological analysis. In addition, the extent of induction were examined by the gene expression of hepatic vitellogenin. As results, we observed significant differences in the extent of induction of ovarian development. The SPH is indispensable to induce breeding. Both of the SPH treatment alone and the cotreatment with SPH plus MT were the most effective hormone therapy for enhaning the maturation of ovarian follicles. About 46% of the most advanced oocyte appeared to be at a GVBD stage in the SPH treatment (GSI=24.6514.7%), more than 76% of the most advanced oocyte to be the GVBD stage in SPH plus MT treatment(GSI=33.7515.63%), but the oocyte composition just showed monomodel distribution. Serial injection of E2 alone or E2 plus SPH did not further stimulate ovarian development, although the effect of E2 on vitellogenin synthesis were obvious and a decrease in the numbers of ovarian follicles was observed, however the ovarian follicles could survive with MT and SPH plus MT treatment.

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Chen, Hsiao-Wei, and 陳筱薇. "Relationship between Anguilla eels coloration and their habitat usage : The case of A. japonica and A. marmorata." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/maq4y8.

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碩士 國立臺灣大學 生命科學系 105 There are 16 species and 3 subspecies of Anguilla being reported worldwide. The eels could be divided into two categories, skin marbled (marbled eels) or skin uniformly colored (plain eels), by surface coloration. The world geographical distribution of the marbles eels and plain eels overlapped in their growth stage. They coexist in the same rivers but grow in the particular region of the river. Therefore, we would like to explore the possible relationship between Anguilla eels coloration and their habitat usage. Additionally, we also explore the molecular mechanisms might be existed to regulate or adapt their choice of habitat. First, we reviewed the previous studies for the eels coloration and habitat tendency to find the relationship between Anguilla eels coloration and their habitat usage, and tried to use A. japonica (as skin uniformly colored) and A. marmorata (as skin marbled) in Taiwan as an example to verify the habitat usage model. Eel distribution in Taiwan was detected by field investigation and environmental DNA (eDNA) analysis. The results of field investigation demonstrated that A. japonica is dominant in the lower reach of the river and estuary, while A. marmorata dominates in the middle to upper reaches of the river. We also found that eDNA derived from A. japonica and A. marmorata was detected at lower reach to middle reach of the Fengshan River, but there was only A. marmorata detected at the uppermost sites in the results of eDNA analysis. The distribution of eels in Taiwan coincides with the results of meta-analysis of eel coloration and habitat choice, the marbled eels may dominate in the middle to upper reaches of the river because of the gravelly environment. In contrast, the sandy and muddy substrates of downstream region may be attractive to the plain eels. The skin pattern of eels would allow a closer match to the visual characteristics of the background, serving as camouflage on yellow eel stage. Moreover, the potent genes in glass eels which may associate with the potential of their upstream migration was also investigated. We suggest that cognitive processes such as learning and memory acquisition and swimming-related muscle fibers composition are involved in upstream migration of A. marmorata.

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Wu, Ching-Hua, and 吳敬華. "Geographic distribution and seasonal species composition of glass eels of the four anguillid eel (Anguilla japonica, A. marmorata, A. luzonensis, A. bicolor pacifica) in Taiwan and Luzon Island, the Philippines." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/57535950101683802411.

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碩士 國立臺灣大學 漁業科學研究所 100 Eel is an important aquaculture species in Taiwan, Japan, Korea and China of East Asia, and the eel fry of aquaculture demand must completely rely on capture in the estuaries from fishermen. However, the glass eel resource has been declining rapidly from 1970-1980. In the Western North Pacific, Taiwan and northern Luzon Island of the Philippines are important producing regions for larvae of several Anguilla species. To maintain and manage eel aquaculture industry, the research on geographic distribution and seasonal species composition of glass eel is needed. According to the DNA molecular technique, four species of freshwater eel were identified in Taiwan and Luzon Island, namely Anguilla japonica, A. marmorata, A. luzonensis (syn. of A. huangi), and A. bicolor pacifica. Several studies have revealed the life history of A. japonica and A. marmorata, but the research about life history for A. luzonensis and A. bicolor pacifica are still rare. The study investigates geographical distribution and seasonal species composition of these four species of glass eel in Taiwan and northern Luzon Island of the Philippines. The results revealed that A. marmorata was the dominant species, occurring year round in Taiwan and northern Luzon Island. While sub-dominant species in northern Luzon Island was A. luzonensis, and presented in the second half of the year, with peak from July to September. Comparing with northern Luzon Island, the amount of A. luzonensis was fewer in Taiwan. Furthermore, the relative abundance (%) of A. bicolor pacifica was rare in Taiwan and northern Luzon Island, and appeared mainly between September and March. However, A. japonica was occurred in Taiwan in winter only, and the distinct geographic tilt was observed. The results revealed that the geographic distribution and seasonal composition of glass eels of four eel species were different, and this difference may be related to reproduction seasons and recruiting temperature preferences of the glass eel.

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Cha, Yuh-Ru, and 查昱如. "Deciphering the transceiptome and gene expression profiles of three common anguillid eels (Anguilla japonica, A. marmorata, A. bicolor pacifica) cultured in Taiwan by next-generation sequencing." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/67054160897188643644.

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碩士 國立臺灣大學 漁業科學研究所 102 The Japanese eel (Anguilla japonica) is a commercially important aquaculture species in Taiwan. Because the full dependence of the glass eel supply caught from the wild for aquaculture, the available glass eel resource thus determines the sustainability of the eel aquaculture industry. In the past decades, glass eel abundances have been declining significantly, especially in the recent years. One piece of glass eel even costs as high as 200 NT dollars. This makes eel aquaculture industry suffer difficult condition. Therefore, the culture of other eel species becomes more and more popular during recent years. Abundant glass eels are imported from other countries, especially for the A. marmorata and A. bicolor pacifica. There are a total of 4 endemic eel species found in Taiwan, with Japanese eel and A. marmorata being the most common ones. The other 2 tropical eel species, namely A. bicolor pacifica and A. luzonensis, are rare in Taiwan. In present, the basic biological information of these aquaculture eel species, however, are still poor. In this study, we obtained transcriptome of A. japonica, A. marmorata and A. bicolor pacifica by Illunina HiSeq 2000. In each species, over 100 million reads were assembled into more than 200 thousand contigs (ave. length>800 bps). Over 40 % of contigs contain protein coding region. By KEGG pathway analysis, over 37% of contigs were annotated and involved in most KEGG metabolism pathway. A. marmorata and A. bicolor pacifica have similar gene expression patterns of digestive enzymes and may have similar dietary requirment, especially; the expression level of enzymes of protein is higher than A. japonica. It indicated that the requirement of protein for A. marmorata and A. bicolor pacifica is more than for A. japonica. In skeletal muscle analysis, slow muscle paly a major role in glass eel stage, and the expression level of gene of slow muscle is higher in A. marmorata and A. bicolor pacifica than in A. japonica. It suggested that the different expression level among three eel species may result in the difference of habitat usage. Thus A. japonica major lives in downstream and both of A. marmorata and A. bicolor pacifica are live in upstream. Finally, we constructed ANGEL database website, it may offer valuable information on biological research for scientists. The website opens to the world for free access. This can greatly increase the visibility of our science power on aquatic research.

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ZHANG, MING-HUANG, and 張銘煌. "Studies on the fine structure of the stomach and the gastric localization and quantitation of carbonic anhydrase activity in the common eels (Anguilla japonica)." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/25041496255016302910.

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Liu, Yi-Hsin, and 劉易鑫. "Studies on antioxidant activities of the extracts from eels Anguilla bicolor pacifica, A. marmorata and A. japonica and anti-inflammation function using cultured RAW 264.7 cell." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/vksxb7.

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碩士 國立臺灣海洋大學 食品科學系 105 The moisture content of short-finned eel (Anguilla bicolor pacifica), giant mottled eel (A. marmorata) and Japanese eel (A. japonica) is between 60.56-63.72%, crude protein 17.61-18.32%, crude fat 17.02-20.06%, and ash 1.03-1.58%. There is no significant difference in proximate composition of three species of eels. The eel meats were extracted with hot water, phosphate buffer saline (PBS) and trichloroacetic acid (TCA), and then get 1000 mg/mL (meat/water) of hot water, TCA and PBS extracts by vacuum concentration. The concentrates were diluted to 50, 100, 200, 300, 400, 500 mg/mL of each extract. The major free amino acids of eels were taurine, glycine, lysine and proline, and the predominant dipeptide was carnosine which was rich in eel meats. The contents of β-alanie and histidine in hot water and PBS extracts were higher than those of TCA extract, but carosine was lower. For the antioxidant capacity, DPPH scavenging rates of 500 mg/mL hot water extracts of short-finned eel, giant mottled eel and Japanese eel were 45.73, 42.24 and 41.46%, reapectively. The rates of hot water extracts were stronger than other extracts, but no significant difference was found in three eels. Chelating activity on Cu2+ of 500 mg/mL TCA extracts were 74.08, 87.51 and 83.24%, respectively, which were stronger than other extracts. Giant mottled eel showed higher activity than other eels. Reducing power was also higher in 500 mg/mL of hot water extracts, which were equal to 17.20, 19.79 and 24.54 ppm of Vitamin C. The power of Japanese eel was significantly higher than giant mottled eel and short-finned eel. Hot water extract showed stronger antioxidant activity than other extracts, and was selected for subsequent cell experiments. The murine RAW 264.7 macrophage cell (RAW 264.7) was induced by lipopolysaccharide (LPS, 1 μg/mL). The cell viability of RAW 264.7 cell treated with hot water extracts (50-500 mg/mL) were higher than 80%. The cell viability was also higher than 80% in the absence of LPS, indicating that RAW 264.7 cells did not cause harm by eel extracts. Three hot water extracts with the concentration of 50-200 mg/mL had a good anti-inflammatory effect by using RAW 264.7 cells induced by LPS. The inhibition rate of nitric oxide (NO) was between 13.0-25.9%, in which short-finned eel and Japanese eel were significantly higher than giant mottled eel. Few NO was released in the absence of LPS indicating that hot water extract would not promote cell inflammation. The results showed that short-finned eel, giant mottled eel and Japanese eel extracts had high content of carnosine and possessed antioxidant ability. The hot water extracts would not cause harm to cells and inhibit the inflammation using RAW 264.7 cells induced by LPS.

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徐幸君. "Residual study of Enrofloxacin in Japanese eel (Anguilla japonica)." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/37811486022260529367.

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碩士 國立嘉義大學 獸醫學系研究所 97 High performance liquid chromatography (HPLC) with fluorescence detector (FLD) was used to exam the concentrations of enrofloxacin and its metabolite, ciprofloxacin, in Japanese eels after administration two different doses of enrofloxacin (20 or 40 mg/kg b.w.) 5 days continuously by oral route. Four different kinds of tissue samples from liver, kidney, muscle and serum were collected for residue studies. The results indicated that when eels were treated with 20 mg/kg of the compounds, the highest concentration was detected at the 24th hours in liver, and the 8th hours in kidney, muscle and serum after administration, and the concentration was 2.31, 14.69, 1.59 and 5.12 μg/mL, respectively. After 768 hours of the treatment, the compounds were still detected in liver and kidney. However after 480 hours in the serum and 600 hours in the muscle, it was not able to be detected. In contrast, when eels were administered by 40 mg/kg of the compounds, the peak was detected at the 8th hours in liver, kidney, muscle and serum after treatment, and the concentration was 3.99, 22.16, 2.33 and 13.10 μg/ml, respectively. Even after 768 hours of different treatments, the compounds were still able to be detected in liver, kidney and serum. However, after 600 hours of treatment, it was undetectable in muscle. In conclusion, kidney is recommended as the best sampling tissue because it is convenient to sample, its quantity is lot, and the residual concentrations of enrofloxacin and ciprofloxacin in it are the highest. With regard to the issue of the sampling timing, a sample collected within 32 days (768 hours) would be useful because the residuals in organs are able to be detected after 32 days of administration caused by the longer half life times of the enrofloxacin and its metabolite, ciprofloxacin.

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Chen, Chia yung, and 陳家勇. "Regulation of Reproductive Endocrines in the Japanese Eel ( Anguilla japonica )." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/81655609034662978748.

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碩士 國立海洋大學 水產養殖學系 90 Abstract The objectives of this studies were to investigate the effects of reproductive and metabolic hormones in the reproductive endocrinology and reproduction in Japanse eel, Anguilla japonica. Salmon pituitary extract (SPE) stimulated brain mGnRH content, pituitary LH content, estradiol and testosterone level. Estradiol and dihydrotestosterone (DHT) potentiated the stimulatory effects of SPE. Eels cultured at low temperatures had a higher pituitary LH and gonadosomatic index (GSI) than eels cultured at high temperatures. Insulin alone stimulated male gonadal development, brain mGnRH and pituitary LH content at a dose-dependent effect. SPE + Insulin could rapidly increase content of brain mGnRH and decrease content of pituitary LH in male eel. Long-term injection of hCG can increase content of brain mGnRH and pituitary LH. hCG + Insulin stimulated the increase of brain mGnRH content in a short time. The data also demonstrated that insulin could potentiate the stimulatory effect of hCG in pituitary LH content. Eels with less gonadal development had higher content of brain mGnRH and pituitary LH and concentrations of plasma LH and estradiol than normal eel. Sex steroids stimulated brain mGnRH and pituitary LH content; but plasma LH levels were not increased as compared to the control. Low dose of cortisol increased brain mGnRH and pituitary LH content. T3 also stimulated brain mGnRH and pituitary LH content at a dose-dependent effect. The study suggest that metabolic hormones were closedly associated with the regulation of reproductive hormones and gonadal development in eels.

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Jeng, Shan-Ru, and 鄭絢如. "The Characteristics of Reproductive Endocrinology in Japanese Eel, Anguilla japonica." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/64577686883547720598.

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博士 國立臺灣海洋大學 水產養殖學系 93 The objectives were to investigate the regulation of mammalian gonadotropin-releasing hormone (mGnRH), pituitary gonadotropins (GtHs), gonadosomatic index (GSI), GtH receptors (FSHR, LHR) and cytochrome P450 aromatase (P450arom) using sex steroids and pituitary homogenates in aqua cultured Japanese eels, Anguilla japonica. We investigated estradiol-17β (E2), testosterone (T), and 5��-dihydrotestosterone (DHT) did not stimulate brain mGnRH content. E2 significantly increased pituitary LH content and LH-β mRNA expression in a dose-dependent manner. T significantly increased pituitary LH content but could not stimulate LH-β mRNA expression in pituitary of female. The FSH-β mRNA expression in pituitary significantly decreased in female treated with E2 or T. E2 or T could not significantly stimulate FSHR and LHR mRNA expression in ovary. Brain mGnRH and pituitary mGnRH, LH content, glycoprotein-�n��z�nLH-β mRNA expression were significantly increased in maturing eels (GSI > 20%) injected with salmon (or catfish) pituitary homogenates. In contrast, the FSH-β mRNA expression was decreased in maturing eels. Glycoprotein-��, LH-β, FSHR and LHR mRNA levels increased but FSH-β mRNA levels decreased after inducing maturation. Eel brain aromatase exhibited a Km of 75nM and a Vmax of 1.14 fmole/min/mg. protein (91.5 fmole/h/mg. protein), indicating an enzymatic activity much lower than in other teleosts but similar to that in mammals. Aromatase inhibitors could significantly suppress brain and pituitary aromatase activity. Comparison with another teleost, black porgy, further confirmed the low activity of aromatase in the eel. The low activity of eel aromatase, may be related to the special life cycle of the eel, and the long delay of puberty before the reproductive oceanic migration. Pituitary aromatase activity and P450arom mRNA expression increased with GSI at all stages. Brain (specially forebrain) aromatase activity significantly increased in early vitellogenic control eels (GSI > 0.8 %) and maturing eels. Ovarian aromatase activity still remained low in the vitellogenic gonad (GSI = 8%). The aromatase activity and P450arom mRNA levels were increased with ovarian development after induced maturation and would decreased after the GSI higher than 22%. E2 o r T could significantly increased aromatase activity and P450arom mRNA expression in brain and pituitary, but not in gonad. Glycoprotein-�n��z�nFSH-β mRNA expression levels in pituitary and were not different in aquacultured and wild eels. The LH-β mRNA expression in pituitary was higher in wild female than in aquacultured female. FSHR mRNA expression levels in aquacultured eels was similar to wild eels. The LHR mRNA expression levels in wild eels were higher than aquacultured eels. The FSHR and LHR mRNA expression levels in testis were higher than in ovary.

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YunPuHuang and 黃蘊璞. "Artificial Induction of Maturation in the Cultivated Japanese Eel, Anguilla Japonica." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/44424398488305094497.

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碩士 國立臺灣大學 漁業科學研究所 89 The cultivated Japanese eel (Anguilla japonica) is usually immature in reproduction, it cannot proceed to accomplish final maturation without first inducing the vitellogenesis. Artificial induction of maturation in Japanese eel has been performed by serial injections of Salmon Pituitary Homogenate (SPH) and DHP, yet still not so effectively. The induction rate of vitellogenesis is not more than 50% by SPH treatment, and eggs with good quality cannot always be spontaneously obtained finally by DHP treatment. Therefore, this experiment was designed to follow Wang (1999), using SPH cotreated with exogenous steroids to improve the induction rate of vitellogenesis, then induced eels to the final maturation. The Japanese eel (504±84 grams) were tagged and separated into three groups randomly: SPH treatment, and SPH cotreated with MT (for 6 weeks only, or weekly injection). The injections were performed once a week to induce vitellogenesis. In addition to in vivo study, this study also examined the effect of DHP and OHP in final maturation in vitro. Result showed that SPH cotreated with MT for 6 weeks could induce more eels to start vitellogenesis than those of SPH alone after 7~8 weeks of the treatments. However, the existence of MT during late vitellogenesis stage would delay but cannot inhibit the hydration to occur. The eels with hydrated oocytes can proceed with induction of final maturation by DHP or OHP. In morphology examination, the intra-ovarian oocytes were transparent and with oil droplets centrally located under a binocular microscope. It was suitable for those oocytes to proceed with induction of final maturation. All of the eels with hydrated oocytes could be induced to GVBD and ovulate at 14~20 hrs after DHP or OHP injection. The eels oviposied at 2~7 hrs after ovulation induced by DHP. In contrast, the eels oviposited within 4 hrs after ovulation by OHP. As the quality of eggs retained in body cavity decreased rapidly after ovulation. The time interval between ovulation and oviposition in OHP group were obviously shorter than in DHP group. Therefore, better eggs can be obtained if the spawner is induced to oviposite spontaneously by OHP.

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Hsiung, Kuan-Mei, and 熊觀梅. "Effect of ENSO events on larval duration of theJapanese eel (Anguilla japonica)." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/17510122508089289088.

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碩士 國立臺灣大學 漁業科學研究所 101 The Japanese eel Anguilla japonica (Temminck & Schlegel) is an important aquaculture species in East Asia countries. However all of the eel fry needed for aquaculture depends on the wild capture. The Japanese eel stock has declined rapidly since 1970s, and the price of A. japonica glass eels has a large increase, thus the eel aquaculture industry is facing serious problems. Therefore, understanding the recruitment dynamics of the Japanese eel is expected to lead to proposals for the utilization, preservation, management, and further study of A. japonica glass eels. On the basis of previous experiments in our laboratory, the total length (TL) of A. japonica glass eels during El Nino periods is usually above the regression line. In contrast, the TL of A. japonica glass eels during La Nina periods is usually below the regression line. In other words, the fluctuation of mean TL oscillation appears to be related to El Nino and La Nina events. Thus, this study aimed to elucidate the relationship between ENSO events and Japanese eel larval duration. This study used the A. japonica glass eels that had been collected from estuaries in Taiwan and China between 2002 and 2013, encompassing three El Nino, three normal, and three La Nina events. After measuring the TL and observing the pigmentation stages of the eel larvae, the otoliths were extracted. The daily increments on the otoliths provide information about larval duration. The results showed that the total length (TL) was longest for A. japonica glass eels during stage VA in normal years (56.7±2.6), while the shortest TL was recorded in La Nina year (55.4±2.5). During stage VB, TL was longest in El Nino years and shortest in La Nina years (55.6±2.7 and 55.6±2.6). The results of the otolith daily increments indicated that, for each pigmentation stage, LD was longer in El Nino years (146.11±12.4) and shorter in normal/ La Nina years (127.22±6.5 and 127.10±8.49). These results indicate that fluctuations in mean TL and mean LD oscillation appear to be related to El Nino and La Nina events. In addition, the tracer experiments indicated that tracers released at 139°E and 14°N took longer to drift to the east coast of Taiwan (Duncan, p < 0.05), whereas tracers released from 139°E and 13°N required a significantly shorter time (Duncan, p < 0.05). This result showed that the A. japonica glass eels drift from different latitude might cause effect on their drifting time. In conclusion, ENSO events are correlate to the latitude shifting of the North Equatorial Current (NEC) bifurcation, then impact the transportation velocity of NEC current and Kuroshio; this might cause some effects to the recruitment dynamics of Japanese eel. However, this study further display that the changing of the starting latitude where the A. japonica drift from was the critical factor which caused by ENSO events that influence the larval duration, thus influence the size of the estuarine glass eels of Japanese eel.

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Ho, Min, and 何. 敏. "Spatial and temporal variability in length of Japanese glass eel, Anguilla japonica." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/qg7454.

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碩士 國立臺灣大學 漁業科學研究所 100 The Japanese eel Anguilla japonica is an important aquaculture species in Northeast Asia countries, however, all of the eel fry needed for aquaculture depends on the wild catch. That the Japanese eel stock has declined rapidly in recent decades has resulted in the decreasing glass eel catch and the eel aquaculture industry is facing serious problems. Therefore, understanding the recruitment dynamics of the Japanese eel can propose references for the utilization, preservation and management of the glass eels. The aim of this study is to investigate the spatial and temporal variation of the total length (TL) of the estuarine Japanese glass eels. This study uses a total of 19,059 Japanese glass eel specimens which had been collected from Taiwan, mainland China, North Korea and Japan for 28 years since 1983. After measuring TL and observing pigmentation stages, the results revealed that mean TL of the glass eels decreases gradually from the stage VA to stage VIA2, but from stage VIA3, there is an abruptly increase. Although both the monthly and annual mean TL varies considerably, the long term trend is not significant. The fluctuation of mean TL oscillation seems has some relationship with El Niño and La Niña events. In general, the TL of Japanese glass eel during El Niño period is above the regression line. Besides, the TL of Japanese glass eel during the La Niña period is below the regression line. In other words, the mean TL of Japanese glass eel in La Niña year was shorter than the other years; this may be due to the shorter larval duration. The spatial analysis of TL of Japanese glass eel reveals that the TL of most Japanese glass eels increases with latitude and this phenomenon may have some relationship with longer larval duration for northern glass eels. In conclusion, the resource of Japanese eel has been decreasing significantly for past 30 years and suffered from global warming. However, there is no significant impact on the TL trend of Japanese glass eels. The ENSO events and the transportation velocity will influence the larval duration, thus influence the size of the estuarine glass eels.

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Hsieh, Ming-Hui, and 謝明惠. "Long term changes of population genetic structure of the Japanese eel Anguilla japonica." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/81650079251770543160.

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碩士 國立臺灣大學 漁業科學研究所 100 Population genetic analysis is commonly used to examine, manage, and conserve widespread species. The Japanese Eel (Anguilla japonica) is widely distributed in East Asia and its population size has dramatically declined since the 1970s. Recent studies using microsatellite loci indicate that panmixia was observed in A. japonica. There is no significant differentiation in the temporal or spatial scale of A. japonica, yet the historical demographics are not k now, such as whether the species suffered genetic bottlenecks, genetic drift, and/or inbreeding depression. We used 7 polymorphic microsatellite DNA loci from 13 geographic locations in East Asia, spanning from 22°N to 40°N, from 1985 to 2012 to understand the genetic diversity of A. japonica. Our data show that A. japonica still exhibits high genetic diversity in terms of average allelic richness (14.78) and observed heterozygosity (0.68–0.85). Inbreeding is rare (FIS= 0.066), and there is no genetic differentiation among annual cohorts (FST= 0.0069). The estimated mean effective population size (Ne) among the 26 years is modest (24.7 to infinity). In conclusion, there is no significant differentiation among annual groups of A. japonica. Simulation studies suggest that the population genetics of A. japonica has been stable for the past two decades, but might experience bottleneck in the past. No evidence of genetic bottleneck is found in the 26 annual cohorts. Accordingly, these data suggest that the population of A. japonica, under the current situation, does not face severe threat of losing genetic diversity.

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Hu, Yau-chung, and 胡耀中. "Mineralocorticoid receptor involves in ionoregulation in Japanese eel (Anguilla japonica) in hypotonic environment." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/58088408706427995925.

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碩士 國立臺灣大學 漁業科學研究所 99 Japanese eels (Anguilla japonica) are catadromous with a delicate hormonal system to maintain normal ionic levels under different salinity. Cortisol is the major corticosteroid in teleost and is considered to be a dual regulator as glucocorticoid and mineralocorticoid. On the other hand, mineralocorticoid receptor (MR) function of ion-retention and its protection from excess cortisol binding by 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) are well known in mammals. Since the ancestral MR appeared in cartilaginous fish, the MR may be functional in teleosts. In ion deficient environment, teleosts maintain their osmolarity by ion-absorptive mitochondria-rich cells (MRCs) with highly-regulated Na+, K+-ATPase (NKA) activity. The cDNA sequence of eel MR has been cloned in this thesis and 11β-HSD2 homolog, e11β-HSDsf was retrived from database. To testify the ion-retention role of MR, I induced proliferation of ion-absorptive MRCs in the gill of Japanese eel, Anguilla japonica under distilled water (DW). In DW transfer, lamellar MRCs distributed abundantly after 48 hours and lamellar MRCs cells distributed on the whole lamella after 24 hours in the DDW transfer. By absolute quantification of RT-qPCR, the MR and e11β-HSDsf mRNA levels were up-regulated in same patterns during time course in DW in the gill, intestine and kidney. There were also more copy numbers of e11β-HSDsf than copy numbers of MR. It is possible that e11β-HSDsf protects MR in eels. The result of in situ hybridization showed that the mRNA of MR localized in the MRCs. NKA activity is an indicator of osmoregulation in both fish and mammals. The relations between MR and NKA activity was investigated by time-course and antagonist treatment. NKA activity decrease to freshwater (FW) level in MR antagonist, spironolactone treatment under the presence of lamellar MRCs. This study suggest the protection of MR by e11β-HSDsf and establish the MR function in ion-retention under hypotonic environment in Japanese eels.

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Lin, Tien-Tsan, and 林天讚. "Expression of Kit Ligand in the Ovarian Development of Japanese eel (Anguilla japonica)." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/39gxbp.

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碩士 國立臺灣大學 漁業科學研究所 105 Japanese eel, Anguilla japonica, is one of economical animal in Asian aquaculture. The reproductive mechanism and strategies of Japanese eel are still unclear, and salmon pituitary homogenate (SPH) induction is necessary to promote ovarian follicle growth. Recently, kit ligand (kitlg) is mainly secreted by the granulosa cells of the ovarian tissue and identified as a cytokine to initiate primordial follicle activation and govern the development of dormant oocytes. However, the precise function and characteristics of kit ligand in the reproduction of Japanese eel remain unclear. This study assumed that the exogenous SPH can stimulate kitlga expression to promote the ovary development, therefore, we characterized the expression patterns of kitlga in the Japanese eel. To investigate the effect of kitlga on the reproductive physiology of Japanese eel, the in vivo and in vitro studies were performed in this research. Japanese female eel were intraperitoneal injected with 7 weekly SPH induction, and the isolated follicular cell from ovary was also established a cell culture platform to investigate the effect of SPH on kitlga gene expression. First, we cloned kitlga cDNA form ovary by reserve transcription polymerase chain reaction (RT-PCR) followed by rapid amplification of cDNA ends (RACE). Next, in order to examine the effect of SPH induction on kitlga expression, we analyzed expression pattern of kitlga messenger RNA (mRNA) by real-time quantitative PCR (qPCR) in ovary tissue and follicular cells. We cloned the full length (1931bp) of kitlga cDNAs of Japanese eel ovary, and the amino acid sequence (275 a.a.) shows high identity with that of other reported teleost kitlga. The results of qPCR found that kitlga gene expression were not significant differences in the control- and SPH group after 7 weekly inductions, and the histological section indicated that the development stage of ovaries has an individual differences. Follicular cells treated with SPH of different concentrations have showed that SPH at a high concentration (1 mg/ml) enhanced the expression of key molecule of steroidogenesis such as cyp19a1 (P450 aromatase), however, the kitlga expression was down-regulated. These results reveal that SPH can promote ovarian steroidogenesis, but the decreased kitlga may have a different role in the ovary development.

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Lin, Yong-Fu, and 林永富. "Climate variability responsible for poor recruitment of the Japanese glass eel (Anguilla japonica)." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6dpuav.

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博士 國立臺灣師範大學 地球科學系 107 Satellite data and assimilation products are used to investigate fluctuations in the catch of Japanese glass eel (Anguilla japonica) in eastern Asian countries. It has been reported that the salinity front has extended farther south, which has shifted the eel’s spawning grounds to a lower latitude, resulting in lower glass eel catches in 1983, 1992, and 1998. Interannual variability in the glass eel catch is strongly correlated with the combination mode (C-mode), but not with the El Niño–Southern Oscillation or supper El Niño events. For example, the 2015/15 El Niño events is a super El Niño events, but it did not result in extremely poor recruitment of Japanese eel in East Asia. The spawning grounds accompanied by the salinity front extend farther south during the C-mode of climate variability, and eel larvae fail to join the nursery in the North Equatorial Current (NEC) and Kuroshio, resulting in poor recruitment in East Asia. We have proposed an appropriate sea surface temperature index to predict Japanese eel larval catch in the East Asia area.

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Chen, Ying-Hou, and 陳穎厚. "Studies of Mitochondria in Oocyte during Puberty in the Japanese Eel, Anguilla japonica." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/66887128333310539899.

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碩士 國立臺灣大學 漁業科學研究所 98 Japanese eel, Anguilla japonica, cannot complete its reproductive maturation in freshwater. After seawater acclimation and exogenous gonadotropins induction, the gonad of Japanese eel can mature and produce gametes. Although artificial induction can stimulate eel spermiation, spawning and success in production of glass eels, even to mature eels, the success rate of producing glass eel and survival rate of larvae are still very low. The onset of fish puberty is controlled by genetic, metabolism and environment factors. The reproductive development of eel is considered to be correlated with metabolism. The puberty onset of eel is accompanied by a silvering process. Not only reproductive maturation but the silvering are consuming processes, thus mitochondria may play an important role. So, in this study, we will examine the mitochondrial distribution and content during puberty and oogenesis, and study the reproductive development mechanism. The cultured Japanese eels with body weight (male: 462 ± 79 g ; female: 580 ± 106 g). Depending on the color of pectoral fin, body color and external morphology, it can be distinguished into four silvering stages (Y1、Y2、S1 and S2). In fresh water, the silvering stage is mainly on Y2 stage. After artificial induction, S1 and S2 stage were shown. And there were no difference between male and female eels. Furthermore, parts of the eels possessed the features of Y2 and S1, pectoral fins became darkness, the edge of pectoral fins was colorless and ventral skin became gray and black. Moreover, after seawater acclimation the eels of particular slivering stage were increased. In this study, the mitochondria of defolliclular oocyte were labeled with mitochondrial-specific fluorescent dye MitoTracker. There were various mitochondrial distribution patterns at different oocyte developmental stage. In the initial stage of previtellogenic oocyte, mitochondria assemble as a mitochondrial cloud (MC). There were one or two MC aggregate(s) in the oocyte during this stage. In the vitellogenic oocyte, the number of mitochondria increased significantly, dispersed in whole ooplasm and mitochondria formed small aggregates. Furthermore, the number of mitochondria increased in ovary after artificial induction with salmon pituitary homogenate and methyl testosterone. These results indicated that mitochondrial distribution patterns vary at different stages and mitochondrial population increases significantly during puberty in Japanese eel. Artificial induction also significantly increased mitochondrial population. Therefore, mitochondria may play an important role during puberty in Japanese eel, and their function during oocyte maturation needs further investigation.

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Chan, Chun-Yang, and 詹鈞陽. "Amoxicillin residue detection and its pharmacokinetics study in the Japanese eel, Anguilla japonica." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/zd6puv.

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碩士 國立中興大學 獸醫學系暨研究所 99 The aims of this study are to develop an accurate method for determination of tissue residual levels of eel fed with amoxicillin (AMX). AMX was extracted from various tissues of eel with phosphate buffer solution by solid-phase extraction. Extracted samples were subjected to derivatization by trichloroacetic acid (TCA) and formaldehyde in boiling water for 30 mins. HPLC separation of AMX was carried out on a Cosmosil 5C18-MS column with mobile phase of 25 mM K2HPO4 (pH 8.5) and acetonitrile at a ratio of 85 : 15 (v/v). The excitation and emission wavelength are 358 nm and 440 nm, respectively. The results revealed that the recoveries of muscle, liver, and serum from eel were 84.7-105.1%, 81.8-104.9%, and 88.6-106.3%, respectively. The tested eels were separated as two groups treated 40 and 80 mg/kg bw/day of amoxicilin following oral administration, respectively. A peak with retention time around 4 min was observed. After given single dose 40 mg/kg bw/day of amoxicillin, via oral administration the pharmacokinetic parameters T1/2, Tmax, Cmax, MRT, Cl and AUCinf were 5.93 ± 0.06 hr, 3 ± 0 hr, 7.03 ± 0.12 ppm, 9.4 ± 0.13 hr, 884 ± 13 mL/hr-kg and 45 ± 0.67 hr × μg/mL, respectively. In addition, our results also showed that the average drug residue concentration in muscle and liver of the low dose group (40 mg / kg-bw) in the first and second day after administration was (180 and 260 ppb) and (70 and 110 ppb), respectively. However, both residue concentrations in muscle and liver of the group in the third day after administrations were under were below the detection limit (lower 30 ppb). Furthermore, our results indicated that the average drug residue amount in muscle and liver of the high dose group (80 mg / kg-bw) in the first and third day after administration was (930 and 1,070 ppb) and (35 and 95 ppb), respectively. Besides, both residue amounts in muscle and liver of the group in the fifth day after administration were under the detection limit.

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SANG, ZI-GANG, and 桑自剛. "Use mitochondrial DNA sequences to evaluate the population structure of Japanese Eel (Anguilla japonica)." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/33387153249304697189.

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Chen, Yen-Hsi, and 陳彥羲. "Structure changes in skin-scale complex during silvering in the Japanese eel, Anguilla japonica." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/22867315434079809513.

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碩士 國立臺灣大學 漁業科學研究所 101 These results for the first time provide the silvering color of Japanese eel is asso-ciation with scale arrangement increase and determine the existence of iridophores in eels by the ultrastructure of the purine crystals deposition in the skin of the Japanese eel. Silvering is a required process in catadromous eels’ downstream migration. Dur-ing silvering, the morphology, physiology and behavior in eels are changed for adap-tation to the upcoming ocean life stage. The ventral skin exhibited metallic silvering is the original definition and important characteristic of silvering. Silvery body color of fish is a structural color, which is caused by overlapping of scales and purine accu-mulation in skin. In salmonids, thyroid hormones play an important role in smoltification. Although the salmonid smoltification the same as eel silvering, the sil-vering of eel are generally regarded association with sexual maturation, the silvering stage are determine by the status of gonad development. This study focus on association between skin-scale complex and skin color of cultured freshwater Japanese eels. The skin was excised from flank region of Japanese eels which cultured in fresh water, and observed by light and transmission electron microscope. Iridophores under the outer chromatophore layer can be found. Scales were embedded in the upper of the dermis. In cultured freshwater Japanese eels, scales develop intercrossly and are overlapped in appearance accompany with metallic hue. This is the first time iridophores have been found in skin of eels. The effect of thyroid hormone and androgen on silvering process was preliminary studied by ex-ogenous drugs. In thiourea (TU) treated eels, melanization can be found in ventral skin and pectoral fins. The results suggest that the scale development in Japanese eel has been started or even finished in the fresh water, not directly induced by gonad maturation. Scale arrangement increase may be accompany with deposition of purine crystals during silvering process. Thyroid hormone may stimulate the onset of silvering, but a complete of silvering or spawning migration behavior express may start after the activity of thyroid gland was decrease.

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Huang, Yan-Rong, and 黃彥融. "Initial artificial induction on the influence of ovary development of Japanese eel (Anguilla japonica)." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/64695559319857196552.

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碩士 國立臺灣大學 海洋研究所 103 The Japanese eel (Anguilla japonica), cannot complete sexual maturation spontaneously under condition of cultivation, and stay in previtellogenic stage, therefore the methods for induction by exogenous sex hormone for gonad development is required. This experiment using freshwater cultivated Japanese eel, 400~550 g in bodyweight, acclimated in seawater in one week, before artificial induction .The exogenous hormones are divided into salmon pituitary extracts (SPE) alone, SPE with MT and SPE with 11- KT , weekly artificially induced, divided into one-week and three-week treatment group. We use JB-4 resin section, and using oocyte stage classification, to observe (1) before and after artificial induction and (2) two androgens effects on ovary characteristics of Japanese eel. The results found SPE induced Japanese eel ovarian follicles, compared to without artificially induction, oil droplets and cortical alveoli significantly increased in ooplasm, and thickening of the outer layer of follicle cells, most advanced oocytes enter the oil droplet stage, showing artificial induction can promote Japanese eel oocytes development. SPE and two androgens effect, in SPE+11-KT treatment group cumulative amount of oil droplets in ooplasm are more than SPE and SPE+MT treatment groups in one-week treatment , but in three week treatment groups, no significant differences are observed between two androgen groups. From the above results, suggest artificial induction can allow ovarian follicles further develop, and two androgen effects show11-KT effects on ovarian follicles in the cumulative of oil droplets are faster than MT effects, shows that androgen are important for ovarian development of Japanese eel.

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Chiang, Chun-I., and 江俊億. "The dramatic elevation of manganese concentrations in the otolith of Japanese eel Anguilla japonica." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/66538216057272380507.

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碩士 國立臺灣大學 漁業科學研究所 97 Trace elements in otolith have been widely applied to reconstruct migratory environmental history of the fish and to discriminate the population structure as well. However, the mechanism of deposition of trace elements in the otolith is still not completely understood. The deposition is a complex biogeochemical process was influenced by the environmental factors, the physiology and ontogeny of the fish, as well as the crystal structure of otolith. It is important to understand the mechanism of the deposition of elements in otolith before otolith microchemistry is used for ecological implication. Manganese (Mn) is one of the 31 important trace elements in the fish otolith. The phenomenon of elevated Mn concentration in the otolith core has been found in many fishes, but the factors affecting the concentrations of Mn in otolith are not well understood. The elemental composition in otoliths of 48 wild yellow-stage Japanese eels was examined by laser ablation-inductively coupled plasma mass spectrometry to understand the change of manganese (Mn) concentration in otolith in relation to the life history events of the eel. The otolith microstructure and crystal structure of CaCO3 were also examined by scanning electron microscopy and Raman spectroscopy. In addition, to understand the effects of ambient Mn concentrations on the otolith Mn concentration, the elvers of Japanese eel were reared for 6 months in the laboratory. Temporal change of Mn/Ca ratios in the otoliths of wild eels can be classified into 3 types: 1) the Mn/Ca ratios in otolith elevated at early life stage of the eel (81.25 %), the mean Mn/Ca ratios at core region of the otolith in the early stage were significantly greater than those at yellow-stage of the eel (p <0.001-0.05, respectively). 2) Mn/Ca ratios elevated in the yellow eel stage but not in the early stage (8.33%), the mean Mn/Ca ratios at the yellow-stage were significantly greater than that the early stage ( p <0.05). 3) no significant elevation (10.42%). The elevated Mn/Ca ratios in the otolith core region were found in most of the eels examined, suggesting that in the Mn was abundantly uptaken from ambient water at early stage of the eel. The Mn/Ca ratios were not significantly different among 3 types of habitat use of the eel which was classified by Sr/Ca and Ba/Ca ratios in otolith of the eel at yellow stage. In addition, Mn concentration in otolith of reared eels were not significantly different between treatments of KMnO4. This further indicated that the elevated Mn concentration in otolith was not related to the salinity and the ambient Mn concentration. The Raman effect also indicated that the elevated Mn concentration in the otolith was not due to different crystalline structures of CaCO3 because all of the otolith were aragonite, not vaterite. The peak Mn/Ca ratios occurred as Sr/Ca ratios drastically decreased to less than 4 ‰ while arriving at the estuary as elver. The peak Mn/Ca ratios in the otolith of elver stage may reflect its physiological and requirement in the upstream migration. The elevated Mn concentration in the core region of the otolith of Japanese eel was also found in the other temperate eels, A. anguilla and A. rostrata, which seems a common phenomenon of the angullid eel. In conclusion, the elevated Mn concentrations in otolith of the eel at early life stage might be due to the effect of physiology rather than environmental effect or crystalline structure of otolith.

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45

Chang, Su-Lean, and 張賜玲. "Studies on the basic aspects concerned with artificial propagation of Japanese eel (Anguilla japonica)." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/05433007724014961707.

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博士 國立臺灣大學 動物學研究所 91 The maturity of pond-reared female Japanese eels (Anguilla japonica) during the inducing maturation was divided into 6 classes (classes 0-5) based on the black coloration of the pectoral fins. Females were injected with 0.5-1 IU/g BW of Human Chorionic Gonadotropin (HCG) at 2 weeks interval in the first month in order to synchronize their maturity up to grades 3-4 within one month after beginning of hormonal treatment. Subsequently, females with body weight over 800 g were injected with a dosage of 4 catfish pituitary homogenate, and 3 catfish pituitary homogenate for those with the body weight below 800 g from the fourth week. Accompanied with shortening of injection interval and reduction of injection dosage at the later stage of induction, final maturation can be attained from 2 months after hormonal treatment. Ovulation or spawning was induced by treatment of 17α-hydroxyprogesterone (17α-OHP, 30 mg/kg BW) or 17 , 20  - dihydroxy — 4 - pregnen-3-one (DHP, 2 mg/kg BW). Spawning was found occasionally in 100 l aquarium by mating one female with 3-5 males. The goal of producing fertilized eggs all year around can be achieved by inducing the female broodstock to spawn in aquaria, with or without stripping. Normal fertilized eel eggs were identified as those with multi-oil droplets based on the fertilization rate, cortical reaction and their buoyancy. Those eggs with unclosed blastopore at the early embryonic stage have lower hatching rate compared with the normal one. Hatched yolk-sac larvae perform an attribute of vertical subsidence. Stocking the yolk-sac larvae in “Quiet Trapezoid Incubation Chamber (QTIC)” can overcome the problem of subsidence and improve the survival rate of yolk-sac larvae. Embryos and yolk-sac larvae can adapt to wide ranges of water temperatures. The embryos at the morula, gastrula and C-shaped stages initially incubated at 23 oC can adapt to the temperatures of 18-28 oC. However, hatching rate was significantly lower when morula and gastrula stages were transferred to 18 oC. Moreover, the C-shaped embryos can tolerate to higher temperature (30 ℃) if acclimated to 26 ℃ prior to trial. One-day old yolk-sac larvae, on the other hand, can temporarily adapt to the temperatures of 3-32 oC. Considering other technicalities with regard to spawning and egg incubation, it is then suggested that water temperature be regulated at the range of 24-26 oC for incubation of Japanese eel embryo, and 26-28 oC for incubation of yolk-sac larvae. The survival of normal and eye-pigmented larvae was significantly higher after transferring the embryos from 30 ppt to 25 and 30 ppt compared to the other salinity treatments tested. The subsidence of yolk-sac larvae was positively correlated with age and the decrease in salinity. Most larvae in 30 ppt water moved to the lower water layer or lay on the bottom from 2 days old, while in the 20 ppt group, almost all larvae from 1 day old sank to the lower layer or lay on the bottom. Moreover, survival rate of yolk-sac larvae significantly decreased by the presence of copepods and bottom substrate (sand and silt). In aspect of larval rearing, two feeding model hypotheses were tested on water column (Model I)；and on the bottom (Model II). The “QTIC” was used as larval rearing facility for the Model I. The feeds prepared for the larval rearing include green water (Mainly Chlorella spp), shrimp flake fluid, fermented fluid from the algal silt, homogenate of cobia eggs, micro particulate feeds and rotifer. For Model II, transparent round-shaped bottom vessels for easier removal of detritus and left-over feeds were used. Softly viscous feeds were made from shrimp flake fluid, homogenate of cobia eggs, vitamins and mixed with eel feed powder. Regardless of the feeds and feeding models used, the larvae could not survive for over 25 days old. From the results obtained in this study, it is therefore concluded that various factors might affect the survival of eel larvae including feeds and feeding method, environmental factors (such as light intensity etc), and water quality control. Each or combination of these factors might play a key role in the improvement of survival of eel larvae, thus further studies are recommended in this field.

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46

韓良娟. "Effects of Oxidized Oil, Antioxidant and Temperature on the Growth of Japanese Eel(Anguilla Japonica)." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/95994822215859037367.

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碩士 國立海洋大學 水產食品科學研究所 83 The effects of oxidized oil and BHT on the Japanese eel (Anguilla japonica) were determined. Japanese eel were treated with POV 27.7 to 97.4 meq/kg oil and 0.02% BHT in their diet for 12 weeks. The growth rate and glutathione content in liver were found to significantly decrease when Japanese eel were fed a diet with supplements of oxidized oil (POV> 50 meq/kg oil) and 0.02% BHT. The hepatosomatic index (HSI) and the level of thiobarbituric acid-reactive substances (TBARS) were found to significantly increase when Japanese eel were fed a diet with supplements of oxidized oil and 0.02% BHT. The pathological symptoms in hepatocytes induced by oxidized oil and BHT were observed under microscope. The lesions indicated that the hepatocytes had hypertrophy, arrangement irregular and necrosis, but these symptoms were alleviated when the fish were switched to the without containing oxidized oil and BHT diet. The Japanese eel were cultured at two temperature (26 amd 32℃) and fed various diets including: moderately (POV 63.0 meq/kgoil) oxidized oil with or without supplement of ascorbic acid and/or DLatocopherol for 8 weeks. The growth rate and glutathione content in liver were found to be significantly higher in the fish fed the diet with supplements of ascorbic acid and DLatocopherol than in fish fed diets with supplement of ascorbic acid or DLatocopherol, and without supplements of ascorbic acid and DL-α-tocopherol. 　　It was also found that the growth rate and glutathione content in liver were lower in fish cultured at 32℃ than in fish cultured at 26℃. The activities of aspartate transaminase (AST) and alanine transaminase (ALT) in plasma and the level of thiobarbituric acid-reactive substances (TBARS) in muscle were lower in the fish fed the diet with supplements of ascorbic acid and DLatocopherol than in other groups. It was also found that the activities of AST and ALT in plasma and the level of TBARS in muscle were higher in fish cultured at 32℃ than in fish cultured at 26℃.

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47

Tseng, Mei-Chen, and 曾美珍. "Study on Population Structure of the Japanese eel Anguilla japonica, using Microsatellites as Genetic Marker." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/68777068797058048873.

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博士 國立臺灣大學 動物學研究所 91 Six novel microsatellite loci, containing (GA)15~17 or (GT)10~19 perfect tandem repeats, were isolated and characterized for the catadromous eel Anguilla japonica. The allelic size of the six loci range from 79 to 226 bp in length. All loci are polymorphic with a mean number of 14.7 alleles per locus and a mean heterozygosity of 0.67, suggesting higher polymorphism than that of freshwater and anadromous fishes, but lower than that of marine fishes. Genotype diversity of the six loci ranged from 0.22 to 0.61 with a mean value of approximately 0.5. Cross-species amplification showed that five of the six microsatellite primers proved to be useful in addressing questions of population genetics for all Anguilla species. The catadromous Japanese eel has an unusual life history, however, controversy remains as to whether its population structure belongs to panmixia or genetic differentiation. The present study used six polymorphic microsatellite loci as genetic markers by which we were firmly able to reject the null hypotheses of panmixia and isolation-by-distance. A significant level of genetic differentiation was determined by Fst and Rst statistics when adjusted using Bonferroni correction. Japanese eel populations shown on the unrooted Neighbor-joining tree are largely divided into three groups: a low-latitudinal group (Shantou in S China, Tanshui, and Fangliao in Taiwan), a mid-latitudinal group (Mikawa Bay in Japan), and a high-latitudinal group (Daecheon-myon in Korea, Yalu River, and Hangzhou in NE China). We agree that the member-vagrant hypothesis fits the elver migration model according to the assignment test. These results suggest that the Japanese eel is distinguishable into three management units (high-, mid-, and low-latitudinal groups) that will be beneficial for further applications of fisheries conservation in the northwestern Pacific Ocean. The existence of temporal genetic variations was tested for 6 polymorphic microsatellite DNA loci of 89 Japanese eel Anguilla japonica collected from a single location in the Tanshui River Estuary, northern Taiwan during 1997-1999. The high Nei’s genetic identity coefficients (0.868-0.941) and exact test of temporal genetic structure revealed no significant differentiation (p > 0.05) among cohorts. Parameters of genetic diversity were examined including mean observed heterozygosity (Ho) (0.695-0.732) and change in the total number of alleles per year (na) (73-81). Significant deviations from Hardy-Weinberg equilibrium appeared in five of 6 loci, due to an insufficient number of heterozygous individuals in all cohorts. A total of 22 private and 14 solitary missing alleles were found in all 6 loci. The decrease in numbers of total alleles and private alleles and the increased number of solitary alleles in consecutive years suggested that genetic polymorphism was gradually decreasing. By Bayesian parameters assay, we found that the effective population was declining. The demographic decline estimated to be 3500-8000 years ago, is significant due to large-scale events such as oceangeographic changes since the most recent glacial stage. Because of its world wide distribution when compared to other freshwater eels, Anguilla marmorata can hardly form a single population. Unlike the temperate eel A. japonica, A. marmorata elver has two peaks of recruitment periods. The present report deals with the comparative study of genetic structure of A. japonica and A. marmorata, and the geographical and seasonal genetic variations of tropical elvers in Vietnam and Taiwan using polymorphic microsatellite markers. Genetic homogenity of the Taiwan elver samples between summer and winter of 2001 indicates that all progeny of A. marmorata belonging to the same spawning group. Although A. marmorata larvae are drifted by different current systems, its genetic structure is highly identical (I = 0.790~0.917). A higher polymorphism in microsatellites further confirm the single population hypothesis of previous studies based on mtDNA data sets. The strong gene flow (Nm>1) among samples of different localities indicates it is a panmictic population in the northwestern Pacific Ocean. Comparison of population structures suggest different migration pattern of elver existed between A. japonica and A. marmorata.

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48

GU, ZHENG-JUN, and 古鎮鈞. "Persistent infection in TO-2 cells with IPN virus isolated from Japanese eel (Anguilla Japonica)." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/24628947216450111447.

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49

HUANG, XU-TIAN, and 黃旭田. "Experimental studies on the pathogenicity of edwardsiella tarda and aeromonas hydrophila in eel, anguilla japonica." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/48385203639488157009.

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50

Huang, Xu-Tian, and 黃旭田. "Experimental studies on the pathogenicity of edwardsiella tarda and aeromonas hydrophila in eel, anguilla japonica." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/69728753980871041278.

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