ENZYMATIC ACTIVITIES RELATING TO THE RESPIRATION AND THE ONSET OF METAMORPHOSIS OF THE ASCIDIAN TADPOLE

Area of Science:

• Developmental Biology
• Marine Biology
• Biochemistry

Background:

• Ascidian larvae undergo significant morphological changes during metamorphosis.
• Oxygen consumption and metabolic enzyme activity are indicators of developmental processes.

Purpose of the Study:

• To investigate the relationship between oxygen consumption, metabolic enzyme activity, and metamorphosis in ascidian larvae.
• To determine the role of Janus green in inducing metamorphic events.

Main Methods:

• Measurement of oxygen consumption in individual ascidian larvae.
• Assay of cytochrome oxidase and succinic dehydrogenase activity.
• Observation of morphological changes induced by Janus green treatment at different larval ages.

Main Results:

• Oxygen consumption increased after hatching and during tail resorption, then decreased post-resorption.
• Cytochrome oxidase and succinic dehydrogenase activities were detected in specific larval tissues and diminished after tail resorption.
• Janus green induced adhesive papillae shrinkage and tail resorption in a time-dependent manner, with both events inducible by 12 hours post-hatching.

Conclusions:

• Enhanced respiratory activities in ascidian larvae are linked to changes in adhesive papillae and tail tissues during metamorphosis.
• Metamorphosis induction by Janus green requires the coordinated changes in both adhesive papillae and tail tissues.