Fig. 3. Molecular characterization of Drosophila rump and generation of a rump null mutation. (A) Genomic region surrounding the CG9373/rump locus. The rump transcript is outlined by the thick black line, with the ORF (lighter shading) and three RRMs (darker shading) indicated. The arrowhead marks the P element insertion P{SUPor-P}^KG02834 in the first intron and parentheses indicate the limits of the rump¹ deletion (dashed line). Transcripts flanking the rump locus are shown in lightest gray. Arrows indicate direction of transcription. (B) Northern blot of total RNA from wild-type (WT) and rump¹ ovaries (O) and 0- to 2-hour-old embryos (E), probed for rump and the loading control rp49 (RpL32 - FlyBase). The trace amount of rump detected in early embryos is due to contamination from zygotic rump expression. (C) Immunoblot of total protein from wild-type (WT) and rump¹ ovaries, wild-type 0- to 2-hour embryos (E), and cultured Schneider cells (S2). Molecular mass standards are indicated in kDa. After transfer, the membrane was cut below the 37 kDa marker. The top portion was blotted with anti-Rump and the bottom with anti-Snf as a loading control. (D) UV-crosslinking of radiolabeled +2' RNA to 0- to 2-hour embryo (E) or ovarian (O) extract from wild-type or rump¹ animals. The position of the p75 binding activity (absent in rump¹) is marked with asterisks. UV-crosslinking reactions carried out in parallel were immunoprecipitated with anti-Rump (Rump) or a control anti-β-galactosidase (βgal) antibody.