The effects of triiodothyronine on RNA synthesis in the liver of Rana catesbeiana were studied using both in vitro transcription of RNA by isolated liver nuclei and in vitro translation of isolated liver poly A RNA in a rabbit reticulocyte lysate system. This study was undertaken since triiodothyronine has been shown to bind specifically to Rana catesbeiana liver nuclei while subsequently causing changes in the levels of numerous proteins. / Melanin free nuclei were obtained by four cycles of short centrifugations followed by ultracentrifugation through 2.4 M sucrose. When these nuclei were analyzed for RNA polymerase activity, extremely low levels of RNA synthesis were observed. The addition of rat liver ribonuclease inhibitor was found to enhance levels of precipitable RNA, but not to the levels observed in other systems. Low rates of transcription were probably due to the presence of an endogenous Ca-Mg dependent DNase. When zinc or spermine was used in place of calcium or magnesium, RNA synthesis continued over much longer time periods, although it still remained low. / Conventional phenol extraction methods yielded degraded RNA upon isolation from Rana catesbeiana liver. Intact total RNA was isolated by modifying the guanidinium thiocyanate procedure of Rutter et al. to include four subsequent guanidine hydrochloride extractions followed by three chloroform-isopentyl alcohol extractions. Poly A RNA was then isolated from total RNA and translated into protein using the rabbit reticulocyte lysate in vitro translation system. Triiodothyronine caused numerous messenger RNAs to increase and others to simultaneously decrease. Antibodies were separately prepared against Rana catesbeiana serum albumin and against an unknown serum protein. This unknown protein appeared to be retinol-binding protein by its migration in two dimensional electrophoresis. Triiodothyronine caused a five fold increase in albumin mRNA and a seven fold increase in the mRNA for the unknown protein. These results support a typical nuclear mechanism for the action of triiodothyronine in amphibian metamorphosis. / Source: Dissertation Abstracts International, Volume: 44-02, Section: B, page: 0483. / Thesis (Ph.D.)--The Florida State University, 1983.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75060 |
| Contributors | SCHULTZ, JAMES JOHN., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 205 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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