Alternatives...
Retroviral infection (MMTV)
- 8 cell embryo treated with recombinant retrovirus
- relatively easy, but technical limitations
- size limited to 8kb, helper virus function “required”
Embryo Stem Cell Method
- Embryo cells maintained in culture (totipotent)
- Cells transfected with recombinant DNA
- Cells microinjected into blastocyst stage embryo
- implantation, etc. as usual
- mosaics produced, resolved by outcross, then inbreed