Fig. 2.
Effect of zinc induction on ALV DNA synthesis and integration. QT6 cells were infected with RAV-1 and either induced with 100 μM ZnSO4 or uninduced. Whole-cell DNA was extracted at the indicated times after infection. Integrated proviral DNA was quantitated by Southern blot hybridization using a probe specific for sequences within a highly conserved region of ALV pol. Arrows indicate the various forms of viral DNA. The bands representing the nonintegrated forms of ALV contain both 1-LTR and 2-LTR circles, because they were not distinguishable in this assay. Total DNA in the region of the gel (Genomic and integrated viral DNA) was visualized by staining with ethidium bromide. C33 cells are chicken embryo fibroblasts that contain a single endogenous provirus and provide a single-copy hybridization standard.