Figure 7.

Triggering of apoptosis in cells transiently transfected with cDNA 668 or the equivalent wild-type sequence, cDNA 668-wt. 293-EBNA cells were transiently transfected by lipofectAMINE. Transfection marker β-galactosidase, inserted into expression vector pcDNA3, was cotransfected with expression vector pcDNAI/Amp either empty, containing cDNA 668, or containing cDNA 668-wt (wt for wild type). cDNA 668-wt was obtained by site-directed mutagenesis performed on cDNA 668, in which the TCA codon was replaced by stop codon TGA. The experiment was performed in triplicate in two different microplates. (A) After 18 h, cells were fixed in one plate and stained with X-gal. A total number of 300 blue cells were counted. The x-axis gives the percentage of blue apoptotic cells. (B) In the other plate, the extent of cell death was quantitate using an ELISA-based assay in which nucleosomes in the supernatant of the transfected cells are purified by a histone-specific antibody and detected photometrically with an anti-DNA antibody coupled to peroxidase.