Structure of viral DNA in a rat cell line, GY1, transformed by Ad12 HindIII fragment-G

Abstract The cell line GY1, established by transformation of a rat cell line 3Y1 with the Ad12 Hin dIII fragment-G (leftmost 6.8%, nucleotide 1 to 2322), contains more than 100 viral copies per haploid genome. The viral DNAs in this cell line were cloned into a phage vector, λgt WESλB, and recloned into pBR322 with their flanking cellular DNAs. Independently isolated 39 clones were analyzed by restriction enzyme cleavage and Southern blot hybridization experiment and divided into 11 classes. Some of classes contained multiple identical clones, at maximum 16 clones. It may be interpreted that amplification of some of the recombined sequences had occurred after the multiple integrations of transfected DNAs within cells. Using five clones from different classes the sequences of recombination sites were determined. Viral DNAs deleted with varying degrees at both ends were flanked by quite different cellular sequences in different clones and no common sequences were revealed around viral-cellular junctions. Tandemly repeated viral DNAS were found in one of the clones to be integrated in a head to tail manner into cellular DNA. The linkage of these two viral DNAs had occurred at the site where parental viral DNAs shared 2 bp. Palindrome structures could be constructed around viral-cellular and viral-viral junction sites and around the regions of parental viral DNAs corresponding to the junction sites in all of the cases investigated.