(A) Southern analysis of T. cruzi clones representing the two types of event observed when the Tcsod locus was targeted. Chromosomal DNA from wild-type (WT) cells and transformed clones (1 and 2) was separated by CHEFE and hybridized with plasmid, Tcsod, or TcgpxII probes. The plasmid DNA identifies the truncated chromosomes that result from integration. (B) Schematic showing the location of the Tcsod locus on the 0.45- and 1.3-Mb chromosomes and the direction of polycistronic transcription (inferred from the orientation of the targeting fragment). Integration at the Tcsod locus deletes the region between the gene and the adjacent downstream telomere. The precise location of the locus on the larger homolog cannot be assessed with accuracy, because it is difficult to resolve the 1.3-Mb chromosome and its slightly smaller truncated product.