The pronuclear injection (PI) is the simplest and widely used method to generate transgenic (Tg) mice. Unfortunately， PI-based Tg mice show uncertain transgene expression due to random transgene insertion in the genome， usually with multiple copies. Thus， typically at least three or more Tg lines are produced by injecting over 200 zygotes and the best line/s among them are selected through laborious screening steps. Recently， we developed technologies using Cre-loxP system that allow targeted insertion of single-copy transgene into a predetermined locus through PI. We termed the method as PI-based Targeted Transgenesis (PITT). A similar method using PhiC31-attP/B system was reported subsequently.
The pronuclear injection (PI) is the simplest and widely used method to generate transgenic (Tg) mice. Unfortunately， PI-based Tg mice show uncertain transgene expression due to random transgene insertion in the genome， usually with multiple copies. Thus， typically at least three or more Tg lines are produced by injecting over 200 zygotes and the best line/s among them are selected through laborious screening steps. Recently， we developed technologies using Cre-loxP system that allow targeted insertion of single-copy transgene into a predetermined locus through PI. We termed the method as PI-based Targeted Transgenesis (PITT). A similar method using PhiC31-attP/B system was reported subsequently.
