FIG. 5.

Comparison of the rates of loss of EBV chromosomes containing or lacking the DS. DNA was isolated from BL30 cells carrying either B-531 or B-ΔDS-8 after 0, 10, 20, and 30 doublings of the cell populations in the absence of G418. A volume of 5 μg of DNA from each sample was cut with EcoRI plus DraI and analyzed by Southern blotting. Staining of the gel by ethidium bromide revealed that equal amounts of DNA were loaded into each lane. A 3.1-kb EcoRI-DraI fragment was detected by probing with EBV sequences from position 125316 (EcoRI) to 125412 (EcoRV). The hybridization signals were quantitated using a beta imager (Molecular Dynamics) and are presented above each lane relative to the signal at 0 doublings. The weaker bands, most prominent in lanes 2, 4, and 9, most likely arose from cutting at “star” sites and were included in the quantitation. Lane 1, DNA from uninfected BL30 cells.