Fig. 7
From: A conserved regulatory program initiates lateral plate mesoderm emergence across chordates
The zebrafish +2.0drl enhancer reads out an LPM program in tunicates and cephalochordates. a Phylogeny of chordates depicting the species used in this study. b–d Ciona robusta embryo at 18 hpf (st 26), electroporated with +2.0drl:EGFP (green), and with Mesp:H2B-mCherry (magenta) to track the B7.5 cardiopharyngeal cell lineage. b, c Representative larva shown with boxed region (b) magnified for detail (c); dashed line indicates midline, anterior to the left, schematic larva depicted in (d) (n = 15/92). +2.0drl-driven EGFP partly overlaps with B7.5 derivatives including atrial siphon muscles precursors (ASMP) (white arrows) and both first and second heart precursors (FHPs and SHPs) (white arrowheads). EGFP is also detected in mesenchymal lineages (white asterisks). e–g Mid-neurula stage (6/7 ss) amphioxus embryo, confocal Z-stack anterior to the left and dorsal to the top; embryo injected with +2.0drl:EGFP (green), counterstained with Phalloidin (red), DAPI (blue), lateral view as 3D rendering (e) and Z-stack sagittal section (f) (n = 61/65). +2.0drl:EGFP showing specific reporter activity in lateral mesendoderm (arrowhead), ventral half of somites (arrows), and elongating somites (double arrows). g Schematic depiction of amphioxus embryo; lateral view on top, dotted line represents transverse section shown below with green depicting domain of +2.0drl:EGFP expression. Scale bar (b) 25 µm, (e) 50 µm
