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Abortive gap repair: underlying mechanism for Ds element formation
1Department of Plant Genetics, The Weizmann Institute of Science, Rehovot, Israel.
Molecular and Cellular Biology
|October 29, 1997
Summary
The maize Ac transposable element rapidly generates Ds elements through DNA rearrangements like deletions and duplications. This process, likely involving abortive gap repair, explains the evolution of these mobile genetic sequences.
Area of Science:
- Genetics
- Molecular Biology
- Plant Science
Background:
- The maize autonomous Ac transposable element generates nonautonomous Ds elements through poorly understood mechanisms.
- Native Ds elements exhibit complex chimeric structures, suggesting extensive sequence alterations from Ac.
Purpose of the Study:
- To elucidate the mechanism of Ds element formation from the Ac transposable element.
- To investigate the nature and frequency of Ac alterations in a controlled system.
Main Methods:
- Utilized transgenic tobacco plants containing a single copy of the Ac element.
- Developed an assay to detect de novo alterations within the Ac element.
- Analyzed DNA rearrangements including deletions, duplications, and insertions.
Main Results:
- Frequent de novo alterations were observed in Ac, distinct from Ds elements and stable genes.
- Rearrangements included internal deletions at short repeats, duplications, and insertions of unrelated sequences.
- Both ancient and newly formed Ds elements displayed similar rearrangement patterns.
Conclusions:
- Ac-Ds elements evolve rapidly via deletions, duplications, sequence reshuffling, and capture of foreign DNA.
- Abortive Ac-induced gap repair, likely via synthesis-dependent strand annealing, is proposed as the mechanism for Ds formation.