1. Duplication by single-strand annealing.
Duplication by single-strand annealing. In this diagram, breaks form at separated sites in different sister chromosomes behind a single replication fork. Breaks may form when a replication fork encounters a nick in its template or by conversion of a simple nick to a double-strand break. In the diagram, these breaks form near sequence repeats. This nicking could be caused by transposase or by fork stalling. The 5′ strands at these breaks are resected, leaving 3′-single-strand extensions that could permit pairing of the repeats. Repair of the paired structure by nucleases and synthesis can lead to a duplication. Simultaneous single strands may coexist at a single collapsed replication fork and allow duplication between nearby repeats as diagramed previously (Lovett et al. 1993) or may form adjacent to transposable elements that are subject to transposase nicking.
Andrew B. Reams et al. Genetics 2012;192:
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