Thyroid hormone-dependent metamorphosis in a direct developing frog

Proc Natl Acad Sci U S A. 2000 Mar 14;97(6):2615-20. doi: 10.1073/pnas.050501097.


The direct developing anuran, Eleutherodactylus coqui, lacks a tadpole, hatching as a tiny frog. We investigated the role of the metamorphic trigger, thyroid hormone (TH), in this unusual ontogeny. Expression patterns of the thyroid hormone receptors, TRalpha and TRbeta, were similar to those of indirect developers. TRbeta mRNA levels increased dramatically around the time of thyroid maturation, when remodeling events reminiscent of metamorphosis occur. Treatment with the goitrogen methimazole inhibited this remodeling, which was reinitiated on cotreatment with TH. Despite their radically altered ontogeny, direct developers still undergo a TH-dependent metamorphosis, which occurs before hatching. We propose a new model for the evolution of anuran direct development.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn / growth & development
  • Antithyroid Agents / pharmacology
  • Bufonidae / embryology*
  • Cloning, Molecular
  • Embryo, Nonmammalian / drug effects
  • Immunohistochemistry
  • Metamorphosis, Biological / physiology*
  • Methimazole / pharmacology
  • Molecular Sequence Data
  • Receptors, Thyroid Hormone / genetics
  • Receptors, Thyroid Hormone / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / metabolism
  • Thyroid Hormones / physiology*
  • Time Factors


  • Antithyroid Agents
  • Receptors, Thyroid Hormone
  • Ribosomal Proteins
  • Thyroid Hormones
  • ribosomal protein L8, rat
  • Methimazole

Associated data

  • GENBANK/AF201957
  • GENBANK/AF201958