P elements can be engineered to transfer genes
P-element-mediated gene transfer in Drosophila. The rosy+ (ry+) eye-color gene is engineered into a deleted P element carried on a bacterial vector. At the same time, a helper plasmid bearing an intact P element is used. Both are injected into an ry– embryo, where ry+ transposes with the P element into the chromosomes of the germ-line cells.