Open AccessExpression of the Xenopus laevis prolactin and thyrotropin genes during metamorphosis.
Author(s) -
Leonard Buckbinder,
Donald D. Brown
Publication year - 1993
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.90.9.3820
Subject(s) - xenopus , medicine , endocrinology , biology , metamorphosis , prolactin , thyrotropin releasing hormone , northern blot , pituitary gland , hormone , messenger rna , thyroid , tadpole (physics) , gene , genetics , botany , physics , particle physics , larva
The cDNAs encoding Xenopus laevis prolactin (PRL) and the alpha and beta subunits of thyroid-stimulating hormone (TSH alpha and TSH beta, respectively) have been cloned from a pituitary library. Results of developmental RNA blot analysis contradict the long-held biological role for PRL as a juvenilizing hormone in amphibia. The pituitary gland of a premetamorphic tadpole expresses PRL mRNA at very low levels. The abundance of PRL mRNA increases late in metamorphosis as a response to thyroid hormone (TH), suggesting that PRL is more likely to have a function in the frog than in the tadpole. TSH alpha and -beta mRNA levels increase through prometamorphosis; this rise does not appear to be regulated directly by TH. At climax, both TH and TSH mRNA levels drop. The sequential morphological changes that characterize prometamorphosis depend upon the gradual increase of endogenous TH, which peaks at climax. This increase in TH in turn depends upon the lack of a traditional thyroid-pituitary negative-feedback loop throughout prometamorphosis.