Figure 5. Mk acts as a critical survival factor during AEC development.

(A) Representative TUNEL-stained sections from limbs of DMSO and iMDK-treated limbs. (B) Representative TUNEL-stained sections from limbs of regenerating mk^WT control or mk^null mutants. (C) Quantification of the % TUNEL⁺ nuclei in the wound epidermis of DMSO or iMDK-treated limbs limbs at 5 dpa (N = 6 DMSO, 6 iMDK) or 11 dpa (N = 8 DMSO, 6 iMDK). (D) Quantification of the percentage of TUNEL⁺ nuclei in mk^WT control and mk^null mutants at 7 dpa (N = 12 mk^WT, 8 mk^null) and 10 dpa (N = 12 mk^WT, 13 mk^null). Asterisks mark auto-fluorescent bone. Each N represents a limb from a different animal. Quantification of levels of blastemal cell death in DMSO/iMDK-treated and mk^WT/mk^null regenerating limbs can be found in Figure 5—figure supplement 1. Two-tailed unpaired student’s t-tests were used for statistical analysis. Graphs are mean ± SD. *p<0.05, **p<0.005. Scale bars: 100 µm. dpa, days post-amputation.

Figure 5—figure supplement 1. Mk is not required for blastemal cell survival.

(A–B) Quantification of the percentage of TUNEL⁺ nuclei in blastemal cells of regenerating stump tissues in DMSO/iMDK-treated (5 dpa: N = 6 DMSO, 6 iMDK; 11 dpa: 8 DMSO, 6 iMDK) (A) or wildtype/mk^null mutant (7 dpa: N = 12 mk^WT, 8 mk^null; 10 dpa: N = 12 mk^WT, 13 mk^null) (B) regenerating limbs reveals iMDK-treated limbs exhibit higher consistent levels of cell death, whereas mk mutant limbs are able to resolve cell death. Two-tailed unpaired t-tests were performed at each time point between the two conditions for statistical analysis. Graphs are mean ± SD. *p<0.05. n.s., not significant; dpa, days post-amputation.