Synchronous changes of morphology and gonadal development of silvering Japanese eel Anguilla japonica

Han, Yi; Liao, I-Chiu; Huang, Yuan-Ko; He, Je-Tung; Chang, Chih-Wei; Tzeng, Wann‐Nian

doi:10.1016/s0044-8486(02)00578-1

Cited by 63 publications

(77 citation statements)

References 24 publications

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“…In this study, we confirmed the colour change for all hormone-treated fish, whereas the control group showed no colour change. Although Han et al (2003) observed more pronounced silver colour on the ventral side and black on the dorsal side in males than females, this was not confirmed in the present study. The low hormone dosage in males might be the cause since the males received only half-dose of the females.…”

Section: Discussioncontrasting

confidence: 99%

Effect of hormone injection frequency on the lipid content and fatty acid compositions in gonad, muscle and liver of Anguilla japonica during artificial maturation

Rupia

Shen

et al. 2013

Aquacult Int

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Two groups of Anguilla japonica were treated with hormone, one on a weekly basis, the other on a biweekly basis. Intramuscular injection was applied at a dose of 0.75 mg/kg BW carp pituitary extract (CPE) plus 150 IU/kg BW human chorionic gonadotropin (hCG) for female fish, while males received half of this dose. The average total lipid content of the gonads from the weekly treated group, i.e. 20.6 ± 1.2 % for females and 18.0 ± 2.3 % for males, was significantly higher than the biweekly treated group, 16.8 ± 0.7 and 15.5 ± 1.3 %, respectively (p \ 0.05). For both muscle and liver, the readings were not significantly different. The gonads from the weekly treated fish had more fatty acids, particularly saturated fatty acids, polyunsaturated fatty acids, highly unsaturated fatty acids, eicosapentaenoic acid (20:5n-3, EPA), docosahexaenoic acid (22:6n-3, DHA) and arachidonic acid (20:4n-6, ARA). Histological examination showed that the ovaries of both the weekly and the biweekly treated fish were mainly at stage IV. However, the weekly treated females had bigger oocyte diameter (722.0 ± 60.9 lm) than the biweekly females (611.6 ± 22.6 lm). These results suggest that CPE and hCG promoted the maturation process for both scheduled induction and that the frequency of hormone injection influenced the biochemical composition of gonads, especially their lipids. Our study describes for the first time the effect of hormone injection frequency on the lipid content and fatty acid composition in the gonads of A. japonica during artificial maturation.

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Section: Discussioncontrasting

confidence: 99%

Effect of hormone injection frequency on the lipid content and fatty acid compositions in gonad, muscle and liver of Anguilla japonica during artificial maturation

Rupia

Shen

et al. 2013

Aquacult Int

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“…The mean GSI and OI of the females increased, while mean DSI decreased significantly during silvering (Table 1). The development of ovaries in relation to GSI, OI and DSI was similar to the previous study (Han et al 2003). Briefly, the yellow eel stage contained mainly Stage 2 (chromatin nucleolus stage) oocytes.…”

Section: Comparison Of Age Size and Morphometric Indices Among Diffsupporting

confidence: 83%

“…The eel pots were set in the day-time ebb tide and the eels were collected in the next ebb tide over approximately 24 h. The eels were trapped in the eel pots when foraging at night-time. The maturity stages of the wild females before and during silvering were divided into 3 categories, yellow, pre-silver and silver, based on skin color and oocyte diameter as described in the previous study (Han et al 2003). Because the occurrence of eels in different stages is seasondependent for the pre-silver and silver eels (Han et al 2003), the silver females were caught in the winter (November to February), while the pre-silver females were caught in summer and autumn (June to October).…”

Section: Methodsmentioning

confidence: 99%

Salinity preference of silvering Japanese eel Anguilla japonica: evidence from pituitary prolactin mRNA levels and otolith Sr:Ca ratios

Han¹,

Yu²,

Liao³

et al. 2003

Mar. Ecol. Prog. Ser.

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The salinity preference of Japanese eel Anguilla japonica during silvering was validated from the viewpoints of physiological ecology by examining the pituitary prolactin (PRL) mRNA expression and the otolith strontium:calcium (Sr:Ca) ratios of the eels of different sexual maturity stages collected in an estuary of Taiwan. The PRL possessed a putative signal peptide of 24 amino acids and a mature peptide of 185 amino acids. RT-PCR and real-time quantitative PCR analyses indicated that the transcript levels of PRL mRNA significantly decreased from yellow to silver stage. On the contrary, the Sr:Ca ratios at the otolith edge of silver eels, which recorded their latest experience of salinity history, significantly increased. The increase in otolith Sr:Ca ratios and the decrease in PRL mRNA expression are consistent with the timing of migration from freshwater to seawater during silvering of the eel.KEY WORDS: Japanese eel · Salinity preference · Otolith · Sr:Ca ratio · Prolactin · mRNA · SilveringResale or republication not permitted without written consent of the publisher

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“…Oocyte diameters (OD, 1 µm) were calculated according to Yamamoto et al (1974). In our previous investigation, the maturity of the wild female Japanese eels before and during silvering were divided into three stages (yellow, pre-silver and silver) based on skin color and histological observations of ovarian development (Han et al 2003b). In the present study, the yellow eels were further divided into juvenile and sub-adult stages based on OD for better comparison (Table 1).…”

Section: Collection Of Wild Eels and Classification Of Maturing Statusmentioning

confidence: 97%

Cloning of the cDNA for thyroid stimulating hormone beta subunit and changes in activity of the pituitary-thyroid axis during silvering of the Japanese eel, Anguilla japonica

Han

Liao²,

Tzeng³

et al. 2004

Journal of Molecular Endocrinology

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The purposes of this study were: (1) to clone the cDNA encoding pituitary thyroid-stimulating hormone beta subunit (TSH ) of the Japanese eel, Anguilla japonica, together with its genomic DNA sequence, for phylogenetic analysis, and to study the regulation of the TSH gene expression in cultured pituitaries; and (2) to investigate the transcript levels of pituitary TSH mRNA and the serum thyroxine profiles at different stages of ovarian development before and during silvering in the wild female eels. The maturity of female eels was divided into four stages, juvenile, sub-adult, pre-silver, and silver, based on skin color and oocyte diameter. The genomic DNA of the TSH subunit contains two introns and three exons, and the TSH protein possesses a putative signal peptide of 20 amino acids and a mature peptide of 127 amino acids. The amino acid sequence identities of TSH mature peptide of Japanese eel compared with those of teleosts and other vertebrates are: European eel (98·4%), salmonids (60·6 -61·3%), carps (52·0 -56·7%), sturgeon (48·4%), and tetrapods (42·9 -45·2%). In in vitro studies of the regulation of TSH mRNA it was found that thyrotropin-releasing hormone increased while thyroxine decreased its expression. RT-PCR and real-time quantitative PCR analysis showed that the transcript levels of TSH subunit increased during eel silvering. The serum thyroxine levels also increased in parallel with TSH mRNA expression during silvering, supporting the hypothesis that the hypothalamus-pituitary-thyroid axis is correlated to silvering in the wild female Japanese eels.

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Synchronous changes of morphology and gonadal development of silvering Japanese eel Anguilla japonica

Cited by 63 publications

References 24 publications

Effect of hormone injection frequency on the lipid content and fatty acid compositions in gonad, muscle and liver of Anguilla japonica during artificial maturation

Effect of hormone injection frequency on the lipid content and fatty acid compositions in gonad, muscle and liver of Anguilla japonica during artificial maturation

Salinity preference of silvering Japanese eel Anguilla japonica: evidence from pituitary prolactin mRNA levels and otolith Sr:Ca ratios

Cloning of the cDNA for thyroid stimulating hormone beta subunit and changes in activity of the pituitary-thyroid axis during silvering of the Japanese eel, Anguilla japonica

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