Fig. 5.

Deletion of eif4e1c impairs CM proliferation in regenerating hearts. (A) Images of sectioned amputated ventricles (7 dpa) from wild-type and Δeif4e1c mutant fish. Sections are stained for Mef2c (green) and EdU (red). Double-positive cells are highlighted in black below using a MIPAR software rendition. Scale bar: 100 µm. (B) Quantification of CM proliferation indices (Mef2/EdU double-positive over total Mef2 positive) in 7 dpa ventricles (average wild type=10.68%, mutant 6.02%; Welch's t-test, **P=0.0054; n=11 and 13, respectively). Error bars represent mean±s.e.m. (C) Cryosections of fresh mutant and wild-type hearts were stained for Succinate dehydrogenase activity. Shown are uninjured hearts (top) and hearts that were ablated genetically using Z-CAT (7 days-post-incubation) (bottom). Scale bar: 20 µm. (D) The mean signal intensity was calculated per given area for Sdh-stained hearts (uninjured average wild type=7.47, mutant=7.57; n=6 and 8, respectively; regeneration average wild type=4.59, mutant=5.06; n=4). Welch's t-test was used to calculate significance (wild type versus mutant uninjured=0.781, wild type uninjured versus wild type regeneration ****P<0.0001, mutant uninjured versus mutant regeneration ****P<0.0001). For every replicate (n=4) the mutant Sdh activity during regeneration (pink) was higher than the wild-type activity during regeneration (red). Error bars represent mean±s.e.m. (E) Diagram of caudal fin regeneration experiments. The blastema is the highly proliferative zone of growth that forms the new fin. (F) Caudal fins were amputated ∼50% in Δeif4e1c mutants and their wild-type siblings and shown are images of fin regrowth 4 days later. (G) There was no significant difference between fin growth in wild type (blue) and mutant (light blue) fish (average wild type=0.849 mm, mutant 0.857 mm; Welch's t-test, P=0.861; n=30 and 26, respectively). Error bars represent mean±s.e.m. Mut, mutant; Wt, wild type.