Fig. 3. A differentially expressed transcript and genomic polymorphisms distinguish Brd¹⁵/TM3 from OreR embryos. (A-C) Reverse-northern analysis. DNA from P1 phage DS06206 was digested with BamHI (lane 1), XbaI (lane 2), BamHI/XbaI (lane 3) or EcoRI (lane 4) then electrophoresed (m indicates marker lane, 1 kb ladder). (A) Ethidium bromide staining of agarose gel. Blots prepared from the gel were probed with ³²P-end-labeled mRNA isolated from OreR (B) or from Brd¹⁵/TM3 embryos (C). A differentially expressed 2.4 kb EcoRI band was subcloned. (D) Northern analysis. Poly-A⁺ RNA isolated from OreR (lane 1) or Brd¹⁵/TM3 embryos (lane 2) was probed with the 2.4 kb EcoRI fragment. (E-G) Southern analysis. Genomic DNA prepared from OreR (lane 1) or from Brd¹⁵/TM3 (lane 2) adults was digested with (E) HindIII, (F) HindIII/XbaI or (G) PstI and probed with a 1.5 kb HindIII fragment (see Fig. 4 for restriction map and probe locations). Digestion with PstI produces the smallest polymorphic fragment, a 280 bp fragment in OreR that is shifted to 7.5 kb in Brd¹⁵/TM3.