Figure 6. Draper-II inhibition of glial engulfment of severed axons is mediated through Corkscrew.

(a) The pan-glial driver repo-Gal4 was used to overexpress UAS-Draper-II in a wild type background or in animals that carried one copy of csw^va199, a dominant negative allele of corkscrew (DN csw). Reduced Csw activity in csw^va199 heterozygotes partially rescued the engulfment phenotype resulting from glial overexpression of Draper-II. Images of GFP-labeled OR85e axons before and 3 days after maxillary palp ablation are all shown as confocal Z-stack projections.

(b) Quantification of experiment in (a). Bars represent mean S.E.M. ***p< 0.0001. D0, Day 0; D3, Day 3.

Genotypes and N values in (a,b):

DN csw = csw^va199/+. (D0 N=10; D3 N=10).

Draper-II overexpression = w;OR85e-mCD8::GFP/UAS-Draper-II;repo-Gal4/+. (D0 N=14; D3 N=10).

Draper-II overexpression + DN csw= csw^va199/w;OR85e-mCD8::GFP/UAS-Draper-II;repo-Gal4/+. (D0 N=10; D3 N=16).

(c) repo-Gal4 was used to drive UAS-Draper-II in animals that also carried UAS-csw^RNAi to knock down Csw expression. Clearance of GFP-labeled OR85e axons was examined 3 days after maxillary palp ablation. Confocal Z-stack projections show GFP⁺ axonal material in the antennal lobes in each genotype before and after injury. Overexpression of Draper-II in wild type animals blocks glial engulfment of degenerating axons, but this engulfment phenotype is significantly reduced when Csw expression is knocked down by RNAi.

(d) Quantification of the experiment shown in (a). Error bars represent S.E.M. ***p < 0.001. D0, Day 0; D3, Day 3.

Genotypes and N values in (c,d):

Draper-II overexpression = w;OR85e-mCD8::GFP/UAS-Draper-II;repo-Gal4/+. (D0 N=10; D3 N=14).

Draper-II overexpression + cswRNAi = UAS-cswRNAi/w;OR85e-mCD8::GFP/UAS-Draper-II;repo-Gal4/+. (D0 N=12; D3 N=16).