Thyroid-like function in the urochordate Ciona intestinalis

In the studies reported in the manuscript I investigated the involvement of Iodine and thyroxine (Thyroid Hormone, T4) in Ciona intestinalis metamorphosis. To date, the mechanisms regulating the metamorphosis of ascidians remain largely unknown. In vivo treatment of swimming larvae with exogenous L-thyroxine and goitrogens (methimazole, thiourea and Potassium Perchlorate), demonstrated the role that the intact thyroid hormone biosynthetic molecular machinery plays in the control of metamorphosis. I further supported the idea of a vertebrate-like thyroid function in tunicates, by reinforcing the phylogenetic link between thyroid gland and the endostyle organ through the identification, amongst the proteins extracted from Ciona endostyle, of a protein, CRELD, apparently not related to vertebrate thyroglobulin, that hypothetically could represent the scaffold for TH synthesis in Ciona intestinalis. My present studies have also demonstrated that the Ciona CiNR1, previously reported as inactive, is a functional thyroid receptor, further strengthening the idea that a thyroid function, comparable to that of vertebrates, is present also in tunicates.