Fig. 4

The careg reporter is activated in other injury models of the zebrafish heart and fin.

(a,b) Ventricle section of careg:EGFP heart at 7 days post amputation (d.p.a.) labelled with F-actin (blue) and antibodies against GFP (green) and embCMHC (red). careg:EGFP expression is activated in the ventricular trabeculae close to the amputation plane of the resected apex (dashed line). N=3. (c–l) Live-imaging of the same fin at different time points post-cryoinjury. Cryoinjury of the caudal fin results in spontaneous sloughing of destroyed tissue within two days after the damage induction, followed by resumed regeneration. Bright-field was combined with fluorescence. (c,d) At 3 h.p.ci. (hours post-cryoinjury), careg:EGFP is not detected in the fin. Ischaemic tissue, which is distal to the cryoinjury plane (blue line), remains integrated with the rest of the body at this early stage. (e,f) At 1 d.p.ci., the majority of the damaged tissue detached from the stump. careg:EGFP is detected proximally to the damaged zone. (g,h) At 2 d.p.ci., the reparation of the distorted margin is accompanied by careg:EGFP expression. (i,j) At 4 d.p.ci., the protruding blastema displays enhanced expression of the careg reporter. (k,l) The advanced regeneration is associated with downregulation of careg:EGFP expression. N=3.