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Fig. 3
lh3 Is Required for Regenerative Axonal Growth and Target-Selective Regeneration
(A–D) Examples of pre-lesion (A) and 48 hpt (B) wild-type motor nerve show robust and directional regrowth. In contrast, pre-lesion (C) and 48 hpt (D) conditional lh3 mutant motor nerve examples show diminished regrowth that often targeted non-dorsal regions (white dashed box, transection site; yellow triangle, dorsal ROI; red arrowheads, misguided fascicles; scale bar, 10 µm).
(E and F) lh3 expression after transection rescued this defect; compare pre-lesion (E) to 48 hpt (F) examples.
(G) lh3 is required for regenerative growth across populations (wild-type sibling, n = 13 larvae, 39 nerves; lh3, n = 13 larvae, 35 nerves; global lh3 rescue, n = 8 larvae, 21 nerves). Camera lucida tracings of regrowth “extent” categories described in Supplemental Experimental Procedures (black, uninjured axons; pink, regenerated axons). Regenerating ventral axons do not require lh3 function (sibling, n = 9 larvae, 25 nerves; lh3, n = 16 larvae, 35 nerves).
(H–K) Modified Sholl analysis reveals that in comparison to siblings (H), fewer lh3 fascicles (I) regrew to the dorsal myotome. This defect was partially rescued by ubiquitous lh3 transgene expression during regeneration (J). (K) These differences were statistically significant after adjusting for developmental dorsal axon patterning in the directionality ratio.