FIG. 1.

Schematic representation of the locations and orientations of the primers used in this work to analyze the transconjugants. The locations of the recombination, conjugation, or regulation modules of the S. thermophilus ICEs are indicated by gray and white rectangles. Recombination sites are drawn as vertical rectangles: black, sequence identical in attL, attR, attI, and attB sites; checkerboards, arm of attR sites and related arm of attI sites; hatched boxes, arm of attL sites and related arm of attI sites. The recombination sites are magnified. The locations and orientations of the primers hybridizing into the ICEs (ICESt1 or ICESt3) and into the flanking sequences are indicated by black arrowheads. Each letter (A to H) indicates a class of primers hybridizing on the same locus in different species (see Table S1 in the supplemental material). The primer pairs A-B, E-F, A-F, and E-B allow the amplification of fragments carrying the attL, the attR, the attB, and the attI sites, respectively. The primer pair C-D allows the amplification of an internal fragment of the regulation module of ICESt1 or ICESt3. The amplification of an internal fragment of the fda gene using the species-specific primers G and H allows the identification of the species. The spectinomycin (spc) or the chloramphenicol (cat) resistance genes introduced in order to tag the ICEs are indicated by a large black rectangle. The sequences between the regulation module and the attL site are specific to each S. thermophilus ICE. The accession number of the untagged ICESt1 and ICESt3 nucleotide sequences are AJ278471 and AJ586568, respectively.