Studies on the regulation of anuran metamorphosis by thyroid hormones and prolactin
Resorption of the tail of the anuran larva during metamorphosis is induced by the thyroid hormones. In contrast, the pituitary hormone prolactin favors growth of the tail fin and inhibits resorption. The present investigations were designed to explore the mechanisms by which the thyroid hormones and prolactin bring about their cellular effects. Incubation of explants of tail fin with derivatives of cAMP was shown to inhibit T/sub 4/-induced resorption of explants in a manner similar to that of prolactin. Likewise, inhibition of phosphodiesterases also inhibited resorption. Prolactin, however, failed to alter the levels of cAMP in cultured explants of tail fin. Although cAMP antagonizes the resorptive effects of T/sub 4/, prolactin apparently does not act by elevating cellular levels of that cyclic nucleotide. Newly synthesized proteins from explants of tail fin were examined by isotopical labeling followed by two-dimensional gel electrophoresis and fluorography. Incorporation of /sup 35/S-methionine into four proteins was increased within 8 to 48 hours after exposure of explants to T/sub 4/. Three of the same proteins appeared to be synthesized more rapidly in explants of fin from tadpoles at metamorphic climax than in fin from tadpoles of premetamorphic stages. These results indicate that treatment of explants with T/sub 4/ or elevation of endogenous levels of thyroid hormones during spontaneous metamorphosis increased the relative rates of synthesis of several proteins. Those proteins are potentially involved in initiating the effects of T/sub 4/ which lead to cell death and resorption of the tail.
- Research Organization:
- Virginia Univ., Charlottesville (USA)
- OSTI ID:
- 6703896
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FROGS
METAMORPHOSIS
LTH
BIOLOGICAL EFFECTS
THYROID HORMONES
THYROXINE
AMP
BIOLOGICAL FUNCTIONS
ELECTROPHORESIS
FLUORESCENCE
LABELLED COMPOUNDS
SULFUR 35
TISSUE CULTURES
TRACER TECHNIQUES
AMINO ACIDS
AMPHIBIANS
ANIMALS
AQUATIC ORGANISMS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
DAYS LIVING RADIOISOTOPES
EVEN-ODD NUCLEI
FUNCTIONS
GONADOTROPINS
HORMONES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LUMINESCENCE
NUCLEI
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PEPTIDE HORMONES
PITUITARY HORMONES
RADIOISOTOPES
SULFUR ISOTOPES
VERTEBRATES
550301* - Cytology- Tracer Techniques