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Flounder metamorphosis: its regulation by various hormones
E G de Jesus1, T Hirano, Y Inui
1Ocean Research Institute, University of Tokyo, Nakano, Tokyo, 164, Japan.
Fish Physiology and Biochemistry
|November 9, 2013
Summary
Thyroid hormones, thyroxine (T4) and triiodothyronine (T3), directly stimulate Japanese flounder fin ray resorption during metamorphosis. Other hormones modulate this response, offering insights into developmental processes.
Area of Science:
- Developmental Biology
- Endocrinology
- Ichthyology
Background:
- Metamorphosis in fish, like the Japanese flounder (Paralichthys olivaceus), involves significant physiological changes.
- Thyroid hormones play a crucial role in amphibian metamorphosis, but their precise function in fish requires further elucidation.
Purpose of the Study:
- To investigate the direct effects of thyroid hormones (T4 and T3) on fin ray resorption in Japanese flounder.
- To examine the influence of other hormones (prolactin, cortisol, sex steroids) on thyroid hormone-mediated fin ray resorption.
Main Methods:
- Utilized an in vitro system for culturing flounder fin rays to assess hormonal effects.
- Conducted in vivo studies to correlate hormonal changes with developmental stages.
- Monitored whole-body hormone concentrations during development and metamorphosis.
Main Results:
- Both thyroxine (T4) and triiodothyronine (T3) directly stimulated fin ray shortening, with T3 being more potent.
- Prolactin, cortisol, and sex steroids did not directly induce resorption but modulated the tissue's response to thyroid hormones.
- In vivo observations corroborated the in vitro findings regarding hormonal interactions.
Conclusions:
- Thyroid hormones are direct effectors of fin ray resorption during Japanese flounder metamorphosis.
- A complex interplay exists between thyroid hormones and other endocrine factors in regulating this developmental process.
- Further research is needed to fully understand the endocrine regulation of metamorphosis in this species.
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