Thyroid hormone induces metamorphosis of flounder larvae

Area of Science:

• * Endocrinology
• * Developmental Biology
• * Ichthyology

Background:

• * Thyroid hormones are crucial regulators of development and metamorphosis in vertebrates.
• * The specific role of thyroid hormone in fish metamorphosis, particularly in flatfish, requires further elucidation.

Purpose of the Study:

• * To investigate the role of thyroid hormone in the metamorphosis of flounder.
• * To compare the effects of thyroxine (T4) and an antithyroidal agent (thiourea) on flounder larval development.

Main Methods:

• * Administration of thyroxine (T4) to pelagic flounder larvae.
• * Administration of thiourea (TU), an antithyroidal agent, to pelagic flounder larvae.
• * Observation and comparison of developmental stages and morphology.

Main Results:

• * Thyroxine (T4) treatment stimulated metamorphosis, producing juvenile-like flounder.
• * Thiourea (TU) treatment induced metamorphic stasis, resulting in giant pelagic larvae.
• * Flounder metamorphosis was significantly influenced by thyroid hormone levels.

Conclusions:

• * Thyroid hormone plays a critical role in flounder metamorphosis, analogous to its function in amphibians.
• * The findings highlight the conserved function of thyroid hormone in vertebrate metamorphosis.
• * Thyroid hormone acts as a key developmental trigger in the transition from pelagic to benthic life stages in flounder.