Fig. 3

Reporter analysis of the Ci-Fn regulatory element. a–c Representative embryos displaying full-length Fn>GFP reporter expression at three different stages, scale bars = 50 μm. a At 8.5 h post-fertilization (HPF, Stage 17) reporter expression is not detected, background staining (faint green) is observed in developing muscle cells. b Mosaic FN reporter expression in the notochord lineage is initially detected at approximately 9.5 HPF (Stage 18/19). c Ci-Fn reporter expression in the notochord continues at later developmental stages as represented by a 12 HFP (Stage 21) embryo. d Schematic illustration of reporter constructs. The 5′ boundary relative to the initiator codon of the Ci-Fn sequence in each construct is identified by numbers on the left. Table on the right summarizes observed patterns of GFP expression. Relative abundances were estimated by comparing numerous transgenic embryos (>100 per construct). For ectopic expression, <1 % indicates the detection of GFP expression in non-notochord tissues in less than 1 in 100 embryos examined. Stippled box notochord enhancer region; white rectangle, core promoter; black rectangle 5′ untranslated region. e Map and reporter expression for deletions and mutations within the Ci-Fn minimal (−1226, −1093) enhancer region. Putative binding sites are underlined. Arrows indicate the 5′ ends of serial deletion constructs