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Fig. 2
Visualization of AP region-specific transcription factor expression in fin fibroblasts and osteoblasts. (A) Expression of fluorescent transgenic reporters in adult pectoral fins. The alx4a:DsRed2 domain ranges from the most anterior to the third ray. The hand2:EGFP domain extends from the posterior edge to the sixth ray of the fin. (B) The AP expression characteristics of alx4a:DsRed2 and hand2:EGFP are maintained throughout regeneration. Arrowheads indicate amputation plane. (C) Longitudinal sections at 4 dpa confirm reporter expression to nearly the distal tip of the fin. Arrowheads indicate amputation plane. (D) Expression of fluorescent reporters in embryonic pectoral fins. At 4 days post-fertilization (dpf), both reporters display region-specific expression. The expression is similar to that of the adult, but the double-negative medial region is not yet defined. (E) Transverse sections indicate that the expression of each reporter is restricted to the fin mesenchyme. The antibody against p63 marks fin epidermis adjacent to the mesenchymal compartment. Arrowheads indicate amputation plane. (F) Transverse sections indicating that both alx4a:DsRed2 and hand2:EGFP are expressed in a population of fin osteoblasts identifiable by Zns-5 immunoreactivity. Arrowheads indicate amputation plane.