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

Han, Yu; Yu, John Yu Lin; Liao, I-Chiu; Tzeng, Wann‐Nian

doi:10.3354/meps259253

Cited by 15 publications

(7 citation statements)

References 31 publications

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“…Thyroid hormone treatment could change the swimming direction of chum salmon fry to downstream (Boeuf 1994, Iwata 1995. Our previous study also found that, during silvering, the Japanese eel migrated from freshwater to seawater (Han et al 2003c). As indicated in the present study, the expression of TSH mRNA was increased significantly (Fig.…”

supporting

confidence: 55%

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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supporting

confidence: 55%

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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“…They then metamorphose into glass eels along the continental shelf and enter estuaries and rivers for subsequent growth (Tesch, 2003;Aoyama, 2009). In recent years, strontium/calcium (Sr/Ca) ratios in otoliths have been used to evaluate likely levels of salinities experienced during the life history of eels (Tzeng et al, 1997;Tsukamoto et al, 1998;Han et al, 2003). The Japanese eel is regarded as a facultative catadromous fish that can grow up in freshwater, estuarine, or coastal environments (Tsukamoto and Arai, 2001;Daverat et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Impact of long-term habitat loss on the Japanese eel Anguilla japonica

Chen

Huang

Han

2014

Estuarine, Coastal and Shelf Science

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“…These facts, and the fact that GnRH and sex steroids have been found to regulate PRL expression in maturing salmon [78], point to a potential role of PRL in the onset of reproductive migratory behaviour in these species. Similarly, Japanese eel (Anguilla japonica) exhibit reduced PRL mRNA expression after 'silvering', when the fish mature and migrate downstream [40], and sticklebacks (Gasterosteus aculeatus) show increases in PRL hormone levels when moving from saltwater to freshwater [57]. These studies highlight the fact that PRL expression is associated with migration in many fish species; however whether PRL actually induces migratory behaviour or whether it is simply part of a pre-adaptive process remains unknown.…”

Section: Migrationmentioning

confidence: 84%

The role of prolactin in fish reproduction

Whittington¹,

Wilson²

2013

General and Comparative Endocrinology

103

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Abstract:Prolactin (PRL) has one of the broadest ranges of functions of any vertebrate hormone, and plays a critical role in regulating aspects of reproduction in widely divergent lineages. However, while PRL structure, mode of action and functions have been well-characterised in mammals, studies of other vertebrate lineages remain incomplete. As the most diverse group of vertebrates, fish offer a particularly valuable model system for the study of the evolution of reproductive endocrine function. Here, we review the current state of knowledge on the role of prolactin in fish reproduction, which extends to migration, reproductive development and cycling, brood care behaviour, pregnancy, and nutrient provisioning to young. We also highlight significant gaps in knowledge and advocate a specific bidirectional research methodology including both observational and manipulative experiments. Focusing research efforts towards the thorough characterisation of a restricted number of reproductively diverse fish models will help to provide the foundation necessary for a more explicitly evolutionary analysis of PRL function.

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

Cited by 15 publications

References 31 publications

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

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

Impact of long-term habitat loss on the Japanese eel Anguilla japonica

The role of prolactin in fish reproduction

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