Additional file 3: Figure S2.

Distribution of Delta nascent transcripts in a late stage 3 embryo. A1 Flat mount of an embryo at the stage with one leg-bearing segment morphologically visible (1LBS stage), hybridized with a Delta probe comprising approximately 95% intron and 5% exon sequence (see Additional file 2: Figure S1). This probe detects unprocessed nascent transcripts much more strongly than spliced cytoplasmic transcripts. At this early stage there are prominent nuclear dots of nascent transcript (magenta arrowheads) in many cells of the peri-proctodeal region (enlarged in panel A3); double nuclear dots are often visible, showing transcription associated with both copies of the gene. In more mature Delta stripes, transcript is still present at high level in the cytoplasm, but nuclear dots are less frequent and less prominent (enlarged in A2). Note that embryos at this stage extend around much of the egg, and are therefore distorted and split at the lateral margins when flattened. The head is to the left. Black arrowhead: mandibular segment an asterisk marks the proctodeum. Scale bar in A1: 200 μm, in A2-3: 20 μm.

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Brena and Akam BMC Biology 2013 11:112   doi:10.1186/1741-7007-11-112