Sequences homologous to a putative origin of DNA replication from Xenopus laevis have been cloned and sequenced. The prototype, Xori, has been demonstrated to enhance the replication of vector molecules microinjected into Xenopus eggs. Thus, it was of interest to isolate additional clones and to compare their sequences in order to determine if common sequence motifs exist, which might provide some insight into gene regulation and DNA replication. Including Xori, six clones were compared. Two of the clones lie in the globin gene cluster; one 5' to the adult (alpha)1 gene, and the other in the second intron of the tadpole (alpha)1 gene. In all clones, the homologous region begins at the same site, but the lengths of the common regions vary from 142 bp to over 300 bp due to heterogeneous 3' ends. Some of the repeats are bracketed by direct and/or inverted repeats, and relatively large palindromes were found 5' to the common region in some clones. These characteristics, and the presence of a repeat 5' to one of a pair of duplicated (alpha)1 genes suggests that Xori may be capable of transposition. The homologous regions are 20 to 30 percent divergent, but contain a number of sequences of interest. Five clones contain 17 elements which are highly homologous to the yeast autonomously replicating sequence, as well as a region of 25 bp which is similar to the SV40 enhancer. However, following transfection of cultured cells, plasmids harboring repeats are progressively lost, and apparently do not replicate. Although the repeats are transcribed at gastrulation, they are not transcribed in oocytes, blood, or in kidney cells in culture, nor are they associated with the nuclear matrix. Implications of these data are discussed. / Source: Dissertation Abstracts International, Volume: 47-06, Section: B, page: 2319. / Thesis (Ph.D.)--The Florida State University, 1986.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75849 |
| Contributors | RIGGS, CHARLES DANIEL., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 121 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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