Timing of Onset of GATA1-Cre Expression and PCR Genotyping of Atrx Alleles
(A) GATA1-cre +/+ transgenic males were crossed to females of the ROSA26 reporter strain (ROSA26 +/−), and embryos were recovered at 0.5 dpc (~16-cell morula stage) and stained with X-gal. Cre-mediated activation of the ROSA26 β-galactosidase reporter allele was detected in all cells in embryos in which both alleles are coinherited.
(B) Top gel: PCR genotyping of Atrx alleles in embryos using primers PPS1.15 (exon 17) and Mxnp30 (exon 20) as described in Protocol S1. The sizes of PCR products from the different alleles are indicated. Both the Atrx Δ18 (resulting from recombination event B in Figure 2A) and the Atrx Δ18Δneo allele (resulting from recombination event C in Figure 2A) are null for full-length Atrx protein. The bottom gel shows products from a PCR reaction (primers DG52/DG53) used to sex embryos as described in Protocol S1. A 450-bp PCR product is amplified from a mouse Y chromosome-specific satellite repeat.