Figure 9. The glial response is regenerative and this depends on Notch^ICD and Pros.

(A,C,D) The GRR gene network influences wound size. (A) The glial wound (pink dashed line) is visualised with anti-GS2, and it decreases upon expression of Notch^ICD in glia (D, quantification). The white dashed line indicates the edges of the VNC. (C) The glial wound area is measured in VNCs labelled with anti-Ebony. Wound area increases in egr¹;pros^voila1/pros^S044116 double mutant larvae. (D) Wound area is measured with anti-GS2. It decreases upon over-expression of Notch^ICD in glia, but it increases in larvae that are also mutant for pros (box plots around the median). (B,E) Expression of Notch^ICD in glia does not rescue naturally occurring cell death, but it rescues stabbing injury induced apoptosis, visualised with anti-cleaved-Caspase-3; in (E) the number of apoptotic cells is quantified with DeadEasy Caspase. (F) Longitudinal TEM sections showing axons enwrapped by glia in wild-type (arrow); upon over-expression of NotchICD in all glia, glial enwrapment is considerably thicker and more prominent than in wild-type (arrows show a couple of examples, rest indicated by g = glia); however, enwrapment is deficient if Notch^ICD is over-expressed in pros mutant larvae (arrows indicate persistent enwrapment), revealing that enwrapment depends on Pros. a, axons, off-white; g, glial cytoplasms and membranes, dark grey to black. (A–E) Wild-type larvae were stabbed at 96 h AEL and fixed 6 h later; controls in (B,E) are non-stabbed VNCs; (F) are wandering stage. (C,D) are boxplots; in (E) error bars are standard deviation (s.d.); * p<0.05, ** p<0.01; *** p<0.001. All glia> stands for expression driven by repoGAL4; wild-type is yw. Sample sizes, statistical tests, and p values are given in Table S1. Genotypes from left to right: (A) (1) yw, (2) w;repoGAL4/UASNotch^ICDmyc; (C) (1) yw, (2) egr¹;pros^voila1/pros^S044116; (D) (1) yw, (2) w;repoGAL4/UASNotch^ICDmyc, (3) pros^S044116repoGAL4/pros^S044116UASNotch^ICDmyc; (E) (1) yw, (2) w;repoGAL4/UASNotch^ICDmyc. (F) prosS044116 repoGAL4/prosS044116UASNotclCDmyc.