Fig. 2

Structure and transcript analysis of the zebrafish Pax6a dual-reporter BAC transgene. (A) Schematic representation of zebrafish BAC DKEY-46C10 showing the location of the Pax6a transcript unit within the BAC. Black boxes denote exons, and bent arrows denote promoters P₀, P₁, and P_alpha. (B) The zebrafish Pax6a BAC was modified by insertion of an enhanced green fluorescent protein reporter cassette (EGFP pA) in-frame with the evolutionarily conserved ATG in exon 4. A Discosoma red fluorescent protein reporter cassette (DsRed-pA) was inserted in-frame into the conserved ATG in exon 8. (C) Whereas transcripts that initiate from the P₀ and P₁ promoters encode for EGFP, P_alpha-initiated transcripts encode for DsRed. (D) Analysis of transcripts from the BAC transgene. RNA was prepared from 3-day old embryos transiently transgenic for the dual-reporter BAC and analyzed by RT-PCR. Transcripts with exon 1 (e1) or exon 2 (e2) also included EGFP, but not DsRed. Transcripts with exons alpha, 5 (e5), 6 (e6), or 7 (e7) also included DsRed. No P₁- or P₀-initiated transcripts contained DsRed.