They then contransfected the 293 cells with Bax-encoding plasmid and survivin-encoding plasmids. The virG protein is a cytoplasmic protein produced from the virG Ti plasmid gene. A similar result also showed for cells transfected with the Fas-overexpressing plasmid. Embryonic cord-blood cells were induced into pluripotent stem cells using plasmid DNA. The "tra" operon includes genes required for conjugation and plasmid transfer. In this case, researchers grow bacteria containing a plasmid harboring the gene of interest. Mutations are introduced by first cloning the target sequence into an appropriate plasmid. Structural instability phenomena are of particular concern for plasmid manufacture, DNA vaccination and gene therapy. A plasmid preparation is a method of DNA extraction and purification for plasmid DNA. At least 25 vir genes on the Ti plasmid are necessary for tumor induction . Both pathogens rely on a conjugative virulence plasmid to cause disease. An example of DNA vaccine plasmid is pVAC, which uses SV40 promoter. The helper plasmid contains the "vir" genes that originated from the Ti plasmid of Agrobacterium. Otherwise, smearing may occur in enzyme restricted form of plasmid DNA. The construction of plasmid vectors is simple and straightforward.