Transfection of Gametes: A Method to Generate Transgenic Animals

Transfection methods. The first transfection procedures occurred in the early 1960s and experiments with different cell types and tissues has now become widespread (Wolff & Lederberg, 1994). Different transfection methods have been employed (Mulligan, 1993): a) The in vitro procedure when foreign genes are introduced into cultured cells or tissues. b) The in vivo method, when genes are directly introduced into the tissue (by injection, aerosol, etc); c) The ex-vivo system, in which cells are transfected in vitro and then introduced into a living organism; b and c) Have been the basis for human gene therapies (Anderson, 1998). The foreign DNA can be used free or associated to different vectors (Mulligan). Vectors are molecules that become associated to DNA and facilitate its entrance into the host cytoplasm and nuclei. The most employed vectors are some viruses (retrovirus or adenovirus), some lipidic molecules and liposomes. On the other hand, DNA has been also employed as a free molecule (naked DNA). History of gamete transfection. The first experiment devoted to transfect the male gamete was done in the rabbi