FIG. 1.

(A) Diagram of the positions of the EcoRI and HindIII sites, numbered according to the B95-8 sequence, surrounding the EcoRI G fragment of Akata DNA targeted for homologous recombination. The boxes above indicate the position of the EcoRI G fragment used as a probe and the insertion of the Neo^r gene at bp 88598. Shown below are the sizes of the fragments expected from DNA from cells harboring wild-type episomes, a mixture of wild-type and recombinant episomes, or pure recombinant episomes after digestion with HindIII and probing with the EcoRI G fragment. (B) Southern blot analysis of DNA extracted from Akata cells harboring wild-type episomes (Wt), a parental clone of Akata cells harboring a mixture of wild-type and recombinant episomes (Wt+Rc), or a clone derived from the parental clone that contains only recombinant episomes (Rc). DNA was digested with HindIII, and the two identical halves of the membrane were cut apart and probed either with the EcoRI G fragment of EBV or the XmnI/HincII Neo^r fragment as indicated. The sizes are indicated in kilobases by arrows.