Figure 2.

Strategy for assembly into an ESAC. (A) A genomic segment, covered by three overlapping cosmids, with the positions of fragments A–D. (B) Schematic of the recombination steps. The first crossover event between pMAB2 and pPAD1 leads to formation of the cointegrate (after recombination via fragment A), while the second crossover event (via fragment B) leads to the resolved cointegrate. The starting pPAC-S1 derivative is then enlarged in a step-wise fashion by cointegrate formation and resolution with the appropriate ts plasmids. Fragments A–D are color-coded as in Figure 1. Abbreviations are as in Figure 1.