DrM1 controls secondary motor axon targeting through BMP inhibition as atlastin 1 and NIPA1 do. (A,C,E,G,I) Immunolabelling of secondary motor neurons (sMN) at 72 hpf using zn-5 (A,G), zn-5 and HA (E), or zn-5 and GFP antibodies (C,I). Lateral views of the trunk, anterior towards the left. White arrowheads, empty arrowheads and arrows indicate misguided rostral nerves, missing rostral nerves and misplaced SMN somata, respectively. (B,D,F,H) Mean percentage of misguided rostral nerves. (J) Mean percentage of hemisegments without rostral nerves. (K) Mean number of misplaced SMN somata per embryo. (B,D,F,H,J,K) Quantifications were performed on 24 spinal hemisegments per larva. The n value for each larval group is indicated under the corresponding histogram bar. **P≤0.01, ***P≤0.001 versus internal controls; $$$P≤0.001 for co-injection comparison; #P≤0.05, ##P≤0.01, ###P≤0.001 versus morphant larvae; Kruskal–Wallis ANOVA test with Dunn's post test. Error bars are s.e.m. (A,B) sMN analysis in larvae injected with MOspATG1, MOatl, MOnipa1 or control (MOscr) morpholinos. (C,D) sMN analysis in larvae injected with sub-efficient doses of MOspATG1, MOspATG2 or MOatl morpholinos or co-injected with the same sub-efficient doses of MOatl and MOspATG1 or MOspATG2 morpholinos. (E,F) sMN analysis in non-heat-shocked or heat-shocked Tg(HspGal4-ACR;UAS:CA-BMPRI-HA) and heat-shocked Tg(HspGal4-ACR) transgenic larvae. (G-K) sMN analysis in non-heat-shocked or heat-shocked Tg(Hsp70:DN-BMPR1-GFP) transgenic larvae injected with MOspATG1, MOatl, MOnipa1, MOspATG2 and appropriate control morpholinos. Scale bars: 50 µm.