In the following study, I have investigated aberrant integration events of the maize Activator/Dissociation ( Ac/Ds) family of transposable elements (TEs) in Arabidopsis. The purpose of the study was twofold: (i) to identify sequence modifications associated with aberrant transposition that are informative regarding the mechanism of Ac/Ds transposition; and (ii) to extend our understanding of the mechanisms by which class II TEs can influence genome structure. This work focuses on a large inversion identified on chromosome II. A lone Ds element comprises one breakpoint of the inversion and the second breakpoint is composed solely of Arabidopsis sequences. The analysis of the sequence modifications present at both breakpoints indicates that the event was precipitated by the abortive transposition of Ds. This is the first event of its kind identified for an Ac/Ds and the event defines a novel mechanism by which these TEs can induce change within a genome. Further, the presence of deletions at both termini of the implicated Ds suggests that the transposition of Ac/Ds involves fully excised intermediates. To obtain further support for this model, a population of Arabidopsis individuals harboring Ds excision events was screened for reintegrated elements. Several integrations were analyzed at the sequence level and compared to wild-type integration sites. While no genome rearrangements were detected, a number of integrations display small deletions within both the Ds termini and the DNA flanking the elements. These results are consistent with the presence of fully excised Ac/Ds intermediates. Further, the results suggest that dissolution of the transposase active complex at different points in the transposition process will result in the formation of distinct aberrant transposition products. During the characterization of the inversion, a novel Arabidopsis TE family, FARE, was identified. The FARE elements are foldback transposons, a heterogeneous and poorly characteri
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.38542 |
| Date | January 2001 |
| Creators | Windsor, Aaron J. |
| Contributors | Waddell, Candace S. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001982791, proquestno: NQ98404, Theses scanned by UMI/ProQuest. |
Page generated in 0.0085 seconds