Figure 6: Both the organizer (Hensen’s node) and Calfacilitin increase intracellular calcium.

(a–e) The organizer induces an increase in intracellular calcium in responding cells starting about 4 h after grafting. This example shows the ratio between green and red emissions of Fluo4/Fura-Red excited at 488 nm 0, 3, 4 and 6 h after grafting (a–d; pseudo-colour encoded as a heat map). Panel e shows a time-scan of the changes in the green channel (Fluo4 signal) in the region of the graft. The site of the grafted node is outlined by a thin line in a. (f–m) Embryo loaded with the calcium indicator Rhod-2 after electroporation with GFP alone (f–h) or Calfacilitin+GFP (i–k), imaged 6 h after electroporation. Calfacilitin increases the calcium signal as compared with GFP alone. Scans showing the relative intensity of the Rhod-2 signal in g,j at the position indicated by the line are shown in (l,m), respectively, (the scan line was positioned parallel to the axis of the primitive streak, ~150 μm lateral to the midline). Scale bar (a–d,f–k), 100 μm.