Fig. 4

Characterization of Et(gata2a:EGFP)^pku418 fish line. (A) Insertion mapping result shows that the Tol2 transposon element (large green arrow) is inserted into the 3rd intron of the nrp2b gene. The transposon insertion contains an EGFP reporter gene driven by the zebrafish gata2a minimal promoter. The direction of the transposon insertion (indicated by the direction of the green arrow) is the same as the direction of nrp2b transcription. The genomic sequence flanking the transposon element is also shown. (B)–(E′) The EGFP expression recapitulates that of nrp2b. EGFP-positive cells reach the primary heart field (red arrows) as early as 19 ss (B, B′). By 21 ss (C, C′), the bilateral myocardium precursors merge to form one intact heart (red arrow), and move to the left axis of the embryo. By 25 ss (D, D′), cranial NCC-derived tissues, including brain neurons (yellow triangles, also in C), branchial arches (red triangles), pigment cells (yellow arrow) and heart (red arrow), are all clearly labeled by the green fluorescence signal. The cranial NCCs continue to migrate, and at 24 hpf (E, E′), some pigment cells (yellow arrows) in the anterior trunk start to be labeled with EGFP, and the cardiac NCCs gradually invade the whole heart tube (red arrow). (F)–(H′) The nrp2b mRNA transcriptional pattern detected by in situ hybridization. (B–E, D′, E′, F–H) Lateral view with anterior to the left and dorsal up; (B′, C′) dorsal view with anterior down; (F′–H′) dorsal view with anterior to the left.