Figure 1.

Applications of transposition to porcine transgenesis. Presented is flow diagram of the primary steps involved in the production of transgenic pigs by somatic cell nuclear transfer (SCNT), pronuclear injection (PNI), and lentiviral transduction (LVT). Each procedure requires the surgical isolation of oocytes or embryos. SCNT requires the production of transgenic donor cells, which can be augmented by transposon-mediated transgenesis (TnT). The donor cells are injected into enucleated oocytes, which are then fused and activated before embryo transfer into a recipient. PNI involves the injection of DNA into the male pronuclei before nuclei fusion. PNI can be augmented by TnT. LVT occurs by injection into the peri-vitelline space of staged embryos. In all cases manipulated embryos are surgically implanted into a synchronized recipient sow. A portion of the recipient sows will maintain pregnancy until parturition. The piglets can then be screened for the presence of the transgene by polymerase chain reaction, Southern hybridization, or detection of marker gene expression.