Figure 1.

BAC coinjections drive expression of a lacZ reporter gene in previously detected Bmp5 expression domains. (A) The position of BAC 551 relative to the Bmp5 gene. Dotted lines at the end of the insert bracket minimal and maximal extent of the insert based on restriction mapping and probe hybridization. The arrows on the 3′ side of the Bmp5 exons indicate positions of chromosome breakpoints in two short ear regulatory mutations, se^30DThWb and se^4CHLd (17). Enhancers previously detected by reporter transgenic work with phage clones (17) are labeled and indicated by dotted lines. (B) Embryos (E14.5–15.0) transgenic for BAC 551 and hsp-lacZ transgenes show reporter gene expression (arrowheads and small arrows) in areas previously detected by phage clone reporter constructs and in the xiphisternum and ureter–bladder (italics), locations also known to express Bmp5 (25). (C) Embryos transgenic for BAC 551 and the Bmp5prom-lacZ transgenes show a very similar overall expression pattern.