Functional Genomics in the Mouse: Phenotype-Based Mutagenesis Screens

Breeding schemes for a genome-wide phenotype-based mutagenesis in the mouse. Recessive ENU-induced visible mutations (m) can be identified by using two breeding schemes. Both schemes involve the mating of mutagenized males (G₀) with wild-type females, followed by breeding of their F₁ progeny (G₁) to wild-type (+/+) partners to establish families of siblings (G₂) sharing the same set of mutations. (A) Random intercrosses are performed among the G₂ progeny, giving G₃ progeny. (B) G₃ progeny for screening are generated by random matings between G₂ females to their G₁ fathers (backcross). (Shaded mice) Carriers of the recessive mutation (m/+); (black mice) recessive mutant phenotype (m/m).