Fig. 1. Generating a rpr–specific mutation. (A) Previously characterized deletions in the 75C1,2 region include H99, which removes rpr, grim and hid, X14, which deletes hid, and X25, which deletes hid and grim (White et al., 1994). Lines represent deleted DNA. Open boxes represent uncertainties in the location of the breakpoints. A deletion that removed rpr was generated by irradiating males carrying a marked P element 225 kb proximal to rpr. The progeny were scored for the loss of the eye color marker. As scored by single embryo PCR, one candidate line, XR38, showed a loss of rpr genomic sequences. (B) An example of single embryo PCR on the progeny of XR38/TM6B parents. Each lane represents the DNA of a single embryo. Primers from an unrelated gene, doom, are used as an internal control (lower band). Lanes with two bands indicate the embryo has both rpr (upper band) and doom. Lanes with no bands indicate insufficient DNA. Lanes with only the lower band indicate a loss of rpr DNA. (C) grim genomic sequences are not affected by this deletion. All embryos from XR38/+ parents show both grim (upper) and doom (lower) PCR products. (D-G) In situ hybrizations show that grim (D,E) and hid (F,G) expression is not detectably altered in XR38/XR38 embryos (E,G). (D,F) wild-type embryos.