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. 1997 Apr 1;94(7):3442–3447. doi: 10.1073/pnas.94.7.3442

Figure 2.

Figure 2

B. nigra rRNA genes are dominant over B. oleracea rRNA genes in the tetraploid, B. carinata. RNA isolated from B. nigra and B. oleracea yielded primer extension products of expected sizes (A, lanes 5 and 7; B, lanes 5 and 8). Primer extension of RNA isolated from natural (A, lane 6) or synthetic (B, lanes 6 and 7) B. carinata lines revealed the presence of B. nigra, but not B. oleracea, transcripts. Synthetic B. carinata lines tested in B and C are the products of reciprocal crosses, revealing that there is no maternal effect. The same primer was used to generate sequencing ladders from promoter DNA clones (A, lanes 1–4, 8–11) allowing the transcription initiation sites (+1) to be accurately mapped. Lanes 13 and 14 in B are controls with no RNA and yeast tRNA, respectively, in the primer extension reactions. Primer extension results were confirmed by S1 nuclease protection (C) using probes specific for B. nigra (C, lanes 2–6) or B. oleracea (C, lanes 7–11) transcripts. Sequencing reaction products were loaded as size markers in lanes 1 and 12.