Fig. 1

HS-mediated trans-axonal signaling corrects pre-target topographic sorting errors

(A) Ventronasal (VN) RGCs of an isl2b:TagRFP donor embryo (WT or ext2^dak mutant lacking HS) were topographically transplanted between 30 and 36 hpf into the VN retina of an isl2b:EGFP ext2^dak mutant host. Pre-target sorting of host dorsonasal (DN) axons along the optic tract was assessed by injecting DiD into the host DN retina at 4 dpf.

(B and C) Diagrams and lateral views of donor VN axons (red) and host DN axons (inverted images) along the optic tract of ext2^dak hosts at 4 dpf.

(B) Ext2^dak DN axons missort along the dorsal branch of the optic tract in ext2^dak hosts transplanted with ext2^dak VN RGCs (arrows).

(C) Missorting of ext2^dak DN axons is corrected after transplanting WT VN RGCs. Scale bar: 50 μm.

(D) Quantifications of the percentage of transplanted ext2^dak hosts with missorted DN axons at 4 dpf. One-sided chi-squared test with Yates’s correction, X2 (1, N = 28) = 2.872, p = 0.0451.

(E) Number of missorted DN axon fascicles in ext2^dak hosts with sorting defects. One-way ANOVA with Tukey’s post-hoc test, p ˂ 0.0005.

(F) Quantification of the displacement index in ext2^dak hosts with sorting defects. One-way ANOVA with Tukey’s post-hoc test, p ˂ 0.0001. Error bars: standard errors.

See also Figure S1.