Fig. 5

Actin-rich invasion components are necessary and sufficient for axon entry. aConfocal z-projection frames from a 24-h time-lapse starting at 48 h post fertilization (hpf) of Lifeact-GFP animals showing navigation of the pioneer axon into the spinal cord in animals treated with dimethyl sulfoxide (DMSO), SU6656, and paclitaxel. White arrows denote the tip of the growth cone. Orange dotted box denotes dorsal root entry zone (DREZ). Axon approaches DREZ at 300 min. bRepresentative intensity profiles of Lifeact-GFP expression at the growth cone in animals treated with DMSO (black), SU6656 (green), and paclitaxel (blue). SU6656-treated axons fail to form actin concentrates, while paclitaxel-treated axons form early and robust concentrates. Gray box denotes the formation of actin-rich invasion components in the DMSO- and paclitaxel-treated animals. c Quantification of axons that entered the spinal cord in animals treated with DMSO (n = 14 dorsal root ganglia (DRG)), SU6656 (n = 20 DRG), paclitaxel (n = 13 DRG), GM6001 (n = 18), purvalanol A (n = 18 DRG), and U0126 (n = 20 DRG). Inhibitors of cell invasion prevent axon entry. d Lateral images taken at 56 hpf of Tg(tnfa:gfp) animals treated with DMSO, SU6656, or/and paclitaxel. Arrowheads denote Tg(tnfa:gfp)⁺ DRG. eCumulative frequency of animals treated with SU6656, paclitaxel, and DMSO that express Tg(tnfa:gfp) at each DRG at 56 hpf; n = 86 SU6656-treated fish, n = 50 paclitaxel-treated fish, n = 48 DMSO-treated fish. f Bar graph of the percentage of DRG that were Tg(tnfa:gfp)⁺ at 56 hpf in animals treated with SU6656, paclitaxel, and DMSO; n = 86 SU6656-treated fish, n = 50 paclitaxel-treated fish, n = 48 DMSO-treated fish. SEM is shown. Scale bars denote 10 µm in (a) and 0.1 mm in (d). One-way analysis of variance (ANOVA) (f)