Triiodothyronine increases translatable albumin messenger RNA in Rana catesbeiana tadpole liver

The effects of both 3,5,3'-triiodo-L-thyronine and spontaneous metamorphosis on Rana catesbeiana liver mRNA were studied using in vitro translation of isolated liver poly(A)+ RNA in a rabbit reticulocyte lysate system. Conventional phenol extraction methods yielded degraded RNA due to high levels of endogenous ribonucleases released upon homogenization of Rana catesbeiana liver. Isolation of intact total RNA was achieved using the potent ribonuclease denaturant, guanidinium thiocyanate. Adult bullfrog serum albumin was purified to homogeneity and a monospecific antibody was elicited against it. A serum protein of 23,000 daltons that migrated near serum albumin on a 6% native gel was also purified to homogeneity. A monospecific antibody was also raised against this protein. Both antibodies were used to quantitatively immunoprecipitate the in vitro translation products of poly(A)+ RNA isolated at intervals following a single injection of triiodothyronine or during various stages of spontaneous amphibian metamorphosis. Triiodothyronine caused a sevenfold increase in translatable albumin mRNA and a threefold increase in translatable mRNA for the 23,000 dalton protein. These increases are consistent with a nuclear initiated mechanism for thyroid hormone action during amphibian metamorphosis.