Fig. 1. Allele-specific expression in preimplantation embryos. RTPCR was used to analyse allele-specific expression of genes within the Kcnq1 domain in C57BL/6J (B6)xMus spretus-distal chromosome 7 (SD7) two-cell and blastocyst stage embryos. Maternal (M) and paternal (P) alleles were distinguished using RFLP or deletion/insertion polymorphisms described in the Materials and methods. For each gene, a representative sample is shown with its corresponding reverse-transcriptase negative control. (A) A schematic of the Kcnq1 domain, with the non-coding RNA Kcnq1ot1 labelled in black, ubiquitously imprinted genes labelled in green and placental-specific imprinted genes labelled in purple. DMRs are marked by black circles. (B) Kcnq1ot1 exhibits monoallelic paternal expression at the two-cell stage. (C) Kcnq1ot1 and Kcnq1 are paternally and maternally expressed, respectively; however, placental specific imprinted genes Tssc4 and Cd81 are biallelically expressed at the blastocyst stage. (D) Table showing the tissue specific imprinting of genes in the locus.