Fig. 5. Enhancer activity of the HUC sequences in vivo. (A) The endogenous locus and HUC-PLAP transgene. HUC 1+2 are indicated by the white boxes, the H19 promoter region by the grey box (H) and the PLAP reporter by the black arrow. S (SpeI) and X (XbaI) are restriction sites used for construction. PCR primers used for genotyping the embryos are indicated. Embryos were confirmed transgenic by PCR genotyping (data not shown). (B-D) Three embryos showing typical PLAP staining pattern obtained. This expression pattern was highly consistent between all transgenic embryos. Non-transgenic embryos, as identified by PCR, failed to show any PLAP expression. D, diaphragm; H, heart; K, kidney; M; Meckel’s cartilage; SC, spinal cartilage; T, tongue. Scale bar in B: 1 mm.