Thyroid Hormone Coordinates Developmental Trajectories But Does Not Underlie Developmental Truncation in Danionins

May 18, 2019
Yinan Hu, Angela Mauri, Joan Donahue, Rajendra Singh, Benjamin Acosta, Sarah McMenamin

Developmental Dynamics - Wiley

Abstract
Background Differences in postembryonic developmental trajectories can profoundly alter adult phenotypes and life histories. Thyroid hormone (TH) regulates metamorphosis in many vertebrate taxa with multiphasic ecologies, and alterations to TH metabolism underlie notable cases of paedomorphosis in amphibians. We tested the requirement for TH in multiple postembryonic developmental processes in zebrafish, which has a monophasic ecology, and asked if TH production was compromised in paedomorphic Danionella.

Results We showed that TH regulates allometric growth in juvenile zebrafish, and inhibits relative head growth. The lateral line system showed differential requirements for TH: the hormone promotes canal neuromast formation and inhibits neuromast numbers in the head, but causes expansion of the neuromast population in the trunk. While Danionella morphology resembled that of larval zebrafish, the two Danionella species analyzed were not similar to hypothyroid zebrafish in their shape or neuromast distribution, and both possessed functional thyroid follicles. Read more