Fig. 7. Promoter usage in transgenic lines. (A) Two possibilities (1 and 2) for promoter usage on the B-p-GFP and B-p-GFP-C transgenes. The arrows indicate two possible transcription start sites on the transgene locus. The white box indicates the 5′ end of exon 2 excluding ATG. The probes are indicated below the transgenic construct. Messages transcribed from exon 1b, the conserved region upstream of exon 2 and the EGFP gene, respectively, are indicated as checked, white and shaded boxes, respectively. (B) Northern analysis using total RNA from B-p-GFP and B-p-GFP-C lines. The size of the EGFP message is indicated on the left side of the blots. Ethidium bromide staining of each agarose gel is shown below each blot. Exposure times: (bottom left-hand panel) B-p-GFP, 5 days; B-p-GFP-C, overnight; (bottom centre panel) B-p-GFP, 2 days; B-p-GFP-C, 1 day; (bottom right-hand panel) 3 days for both transgenes.