The synthesis of RNA in isolated nuclei from two sea urchin species was studied. Isolated nuclei from sea urchin embryos synthesize a variety of RNAs in vitro. Two small RNAs, 5S rRNA and N1 RNA, made in isolated nuclei are identical to the small RNAs detected in vivo by hybridization selection with specific cloned sea urchin DNAs. RNAs complementary to DNA clones for histone mRNAs and rRNAs were also detected among the in vitro transcripts. The rRNAs appear to initiate and terminate transcription in the isolated nuclei near the correct DNA sequences. Synthesis of these four RNAs faithfully in the isolated nuclei encompasses the activities of all three RNA polymerases. / The addition of cell extracts modifies the activity of the RNA polymerases in the isolated embryo nuclei. Extracts from sea urchin eggs specifically inhibit RNA polymerase III activity in the isolated nuclei. This activity was purified from the crude egg extracts approximately fifty fold. The inhibition of RNA polymerase III does not appear to be due to a nonspecific activity in the egg extract. The partially purified inhibitor from the egg extract also inhibits RNA polymerase III in DNA dependent transcription assays from mouse and Drosophila. The inhibitor probably interferes with RNA polymerase III initiation by an unknown triphosphate dependent mechanism. / The activity of the inhibitor is destroyed within thirty minutes of fertilization. The rapid destruction of the inhibitor activity by fertilization suggests that this activity is biologically relevant. The inactivation of the inhibitor may be at least partially due to the ionic changes associated with fertilization. The activity of the inhibitor may be related to a 135,000 molecular weight protein which can be detected in preparations from eggs but not in parallel preparations from embryos which lack the inhibitor. / This dissertation demonstrates in an in vitro assay a possible control mechanism for RNA polymerase III activity in sea urchin development. It is conceivable that such a mechanism is operative in other organisms as well. / Source: Dissertation Abstracts International, Volume: 43-09, Section: B, page: 2884. / Thesis (Ph.D.)--The Florida State University, 1982.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_74936 |
| Contributors | MORRIS, GILBERT FRANKLIN., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 191 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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