A, restriction map of the LdASNA locus and the predicted chromosomal rearrangements occurring during HYG and NEO replacement of ASNA in the chromosomal locus. B, Southern blot analysis of WT Bob, single transfectant ASNA/NEO, and double transfectant ASNA/NEO/HYG. Genomic DNA was digested with XhoI, separated on a 0.6% agarose gel, and probed with the 5′-UTR of LdASNA. Molecular size markers are indicated to the right of the blot. C and D, blot in B was striped and reprobed with the NEO or HYG gene, respectively, to indicate the presence of NEO and HYG in single and double transfectants.