Fig. 4. The mouse Hoxa3 locus: transgenic constructs tested for regulatory activity. At the top is a diagram of the genomic region and below an expanded view illustrating the wild-type and mutated genomic fragments linked to a lacZ vector used for stimulating reporter activity in transgenic analysis. The gray box indicates the conserved region whose sequence is shown in Fig. 3. The KrA-binding site is marked by a red box, the HOX/PBC-A site by a blue circle, the HOX/PBC-B site by a purple circle and the Prep/Meis site by a white circle. The black triangle (Post) represents elements that direct posterior expression in mesoderm and neural tissue; they function independently of the segmental elements. Black X in white squares or circles mark mutated sites. The construct numbers (#) for each fragment and a summary of their domains of expression in r5, r6 and posterior (p) regions is indicated at the right of each fragment. Details of the timing and numbers of expressing embryos are provided in Table 1. Restriction sites are RV, EcoRV; A, AvaI; S, SmaI; P, PstI; and N, NotI.
