Fig. 2.

Two-breakpoint rearrangements. (A) Here, we show three genomes, each pair of genomes differing by a single two-breakpoint rearrangement. The genome on the left consists of two rings, and those on the right each have a single ring. The arrows indicate the type of two-breakpoint operation that transforms the one genome into the other. In each operation, four free ends (a, b, c, d) are rejoined in pairs. (B) Reciprocal translocation between two contigs. (C) Inversion, circularized excision, and circularized incision of a segment in a contig.