FIG. 2.

WT and KO alleles of the CD3ɛ and CD3ζ genes can be distinguished by PCR. Genomic DNA samples from the mouse strains B6, CD3γδɛζ^−/−, and their F1 cross (B6 × CD3γδɛζ^−/−) were tested by PCR for the amplification of either the WT or KO alleles of the CD3ɛ (A) and CD3ζ (B) genes. For each CD3 gene and mouse strain tested, the PCR amplifications of the WT and KO alleles were mixed and loaded together in 2% agarose gels. Arrowheads indicate the size of the PCR products found in the gels. As expected according to each genotype, B6 and CD3γδɛζ^−/− mice generated single PCR products from the either the WT or the KO alleles, respectively, while F1 mice displayed heterozygosity (Het) by generating the PCR products for both alleles.