FIG. 1.

Insertional inactivation of sqdX. (A) Restriction and ORF map of the plasmid pSYB and the inactivation plasmid pDL2. The black bar indicates the location of the probe used for hybridization, and the open arrow indicates the neomycin phosphotransferase cassette. Restriction sites: A, BamHI; E, SpeI; H, HindIII; K, KpnI; O, XhoI; P, PstI; S, SalI. (B) Autoradiograph of a Southern blot showing genomic DNA from Synechococcus wild type and 7942ΔsqdX mutant. The DNA was cleaved with HindIII and probed with the fragment indicated in A. The approximate size of the three diagnostic fragments is indicated in kb.