FIG. 2.

Plasmid for P. tetraurelia transformation. Plasmid pPXVII-TER was constructed as described in Materials and Methods. Wild-type and mutated TER genes, including nucleotides −240 through +325, were cloned so that the direction of transcription is toward the terminus of linearized plasmids. Shaded regions are indicative of transcribed nucleotides. A bacterial origin of replication (ORI) and ampicillin resistance marker (Amp^r) are as indicated. Solid arrows represent tandem G₄T₂ telomeric repeats, located at the termini when plasmids are linearized by SfiI digestion. Restriction sites: Sa, SalI; Sc, SacI; Sf, SfiI; Xb, XbaI (Xb); Xh, XhoI. The approximate size of the pPXVII-TER construct is 4.3 kb (figure not drawn to scale).