FIG 1.
Neutral sites in the genome of Synechocystis PCC 6803. (a) Insertion of reporter cassette into neutral sites (NS). Double homologous recombination was used to integrate a cassette containing eyfp and a Kmr marker into each neutral site, replacing approximately 100 bp in the middle of each site. (b and c) Genomic DNA was extracted from mutants grown with (b) and then for 30 days without (c) antibiotic selective pressure, and PCR using flanking primers in the 5′ and 3′ neutral site flanking regions was performed to test for the presence of the desired mutations and the relative frequency of mutant alleles. Lanes: PC, positive-control PCR performed on the suicide vector used to transform Synechocystis PCC 6803; M, colony PCR performed on the Synechocystis PCC 6803 mutant strain; WT, colony PCR performed on wild-type Synechocystis PCC 6803.