Expression analysis. (A) Schematic of gene locations at the mouse Igf2r/Airn locus: transcription start sites (bent arrows), Igf2r (light grey), and Airn (dark grey). (B) RT-PCR analysis of genes in the cluster shows expression of Igf2r at E6.5 and E7.5, as well as Airn expression in the E6.5 VE and E7.5 EM and EX. The other genes in the cluster are not expressed at appreciable levels during gastrulation. (C) SSCP analysis of Igf2r expression shows biallelic expression in the E6.5 EPI, while the paternal allele is silent (imprinted) in all other tissues and stages examined. (D) RT-PCR demonstrates that Airn is not expressed in epiblast but is paternally expressed (E) in all other samples. Two embryos (one per lane) shown for each tissue/stage for each assay. EPI, epiblast; VE, visceral endoderm; EM, embryonic portion of E7.5 embryo; EX, extraembryonic portion of E7.5 embryo. Red box highlights the non-imprinted status of Igf2r and lack of Airn expression in the E6.5 EPI. B, B6 allele; P, PWD allele. +, pooled adult kidney, liver, brain, and heart cDNA. Parental tissue used in (C-E) is adult kidney.