Thyroid hormone metabolism and peroxidase function in two non-chordate animals

Area of Science:

• Endocrinology
• Evolutionary Biology
• Marine Biology

Background:

• Thyroid hormone (TH) signaling is crucial for mammalian metabolism and homeostasis.
• TH regulates metamorphosis in amphibians and lampreys, with suggested roles in basal chordates.
• Evidence indicates TH-related functions in invertebrates, but synthesis mechanisms remain largely unknown.

Purpose of the Study:

• To investigate endogenous thyroid hormone synthesis in invertebrates.
• To explore the functional roles of TH in invertebrate development and energetics.
• To identify genes involved in TH synthesis in non-chordate animals.

Main Methods:

• Thin-layer chromatography to detect endogenous TH.
• Pharmacological experiments to assess TH effects on development.
• Gene identification (LvTPO, AcaTPO) and expression pattern analysis.

Main Results:

• Endogenous TH synthesis confirmed in Aplysia californica and Lytechinus variegatus.
• TH administration accelerated metamorphosis and affected skeletal development in sea urchins.
• Novel peroxidase genes (LvTPO, AcaTPO) identified with sequence similarity to vertebrate TH synthesis enzymes.
• Expression patterns suggest roles in metamorphosis and energy regulation.

Conclusions:

• Thyroid hormone synthesis and signaling are present in diverse invertebrate groups.
• TH plays a significant role in invertebrate metamorphosis and development.
• The identified peroxidase genes are potential key players in invertebrate TH synthesis, offering insights into the evolution of TH pathways.