Fig. 5. An oligonucleotide (30mer) encompassing the intact binding motifs for homeo- and paired domains confers expression in myogenic progenitor cells in limb buds and enhances expression in somites. Oligonucleotides with wild-type sequence (A-D), mutated homeobox binding site (E,F) and truncated sequence lacking the potential Pax3-binding sites (G,H) were used to generate transgene constructs as illustrated schematically. ß-Gal staining in whole mount of transgenic embryos demonstrates that dimerized wild-type oligonucleotide directs robust transgene expression in limbs and somites from E10.5 to 13.5 (A-D). By contrast, embryos containing the transgene in which the homeobox consensus sequence TAATT has been mutated (highlighted by blue letters) do not show expression in limb buds and exhibit drastically reduced expression in somites at E11.5 (E) and E13.5 (F). Likewise, a truncation of the oligonucleotide sequence that retains the homeobox but removes the potential Pax3 and paired domain binding sequences results in embryos that fail to express the transgene in limb buds and only weakly express it in somites (G,H).