Effect of thyroid hormones on the switch from larval to adult hemoglobin synthesis in the salamander Pleurodeles waltlii.

The evolution of globin chain synthesis was studied in larvae treated either with thyroxine or with an anti-thyroid substance. Thyroxine treatment accelerated the rate of Hb switching; it induced a preferential synthesis of adult globins while the synthesis of larval globins decreased rapidly. Treatment with thiourea did not prevent the Hb transition, which occurred even at concentrations of thyroid hormones that did not permit induction of anatomical metamorphosis.