Transgenic Animals

Transgenesis is the deliberate introduction of extra, foreign (exogenous) DNA — the transgene — into an animal's genome to create a new characteristic that is then stably passed on to its offspring; the resulting animals are called transgenic animals, or genetically modified/engineered organisms. Producing one involves several defined steps: identifying and isolating the desired gene; choosing a delivery method, usually a viral vector or direct transfer; combining the gene with that vector; introducing the vector-gene combination into cells, tissue, an embryo or a mature individual; and finally confirming that the foreign gene has actually integrated and is being expressed in the resulting tissue or animal. Mice, rats, rabbits, pigs, cows, goats, sheep and fish have all been made transgenic this way. The applications are broad: transgenesis is a research tool for studying gene expression and development in intact organisms; it improves genetic traits in livestock; transgenic animals serve as disease models for cancer, Alzheimer's, cystic fibrosis, rheumatoid arthritis and sickle cell anaemia, helping researchers test new treatments; they act as living factories (bioreactors) for medically or pharmaceutically important proteins; transgenic mice are used to test vaccine safety; other transgenic line …