Identification of hemizygous mice among animals belonging to the F1 generation. (a) Agarose gel electrophoretic analysis of PCR products obtained by the amplification of genomic DNA purified from eleven mice with primers TransF and TransR, recognizing the transgene sequence. The arrow indicates the position of the expected 154 bp product; the sex of mice having generated a specific amplification band is also shown. M, molecular weight ladder, pUC Mix Marker 8 (Fermentas). (b) Human β-globin allele quantification by real-time PCR using primers and probes specific for human β-globin (Hbβ) gene and mouse cytoplasmic β-actin (Actβ) gene. Results of analysis of transgenic hemizygous mice TG21, TG24, and TG27, together with the founder mouse TG1, are reported as fold of human β-globin allele amount quantified with respect to the murine β-actin gene.