Figure 1.

Targeted mutation of the Olig1 gene and phenotypes of Olig1-null mice. A, Schematic for FLPase-mediated removal of the PGKneo cassette through breeding with FLPeR (Flipper) mice. PGKneo, Neomycin gene driven by the PGK promoter. B, The lifespan of Olig1-null (-/-) mice (46 mice tested) ranges from P13 to P17, which is an active period of oligodendrocyte myelination. All Olig1 heterozygotes (+/-) (95 mice tested) have a normal lifespan, as do their wild-type littermates. C, Olig1-null mice exhibit abnormal clasping of all limbs and are motionless when held upside down, compared with age-matched littermates, which are active and extend their limbs. DTA, Diphtheria toxin.