Syn4 is required for the CaP axons formation.
(A–D') Embryos at 26 hpf show PMNs in green fluorescence. (B,B') Syn4 morphants show shortened and branching CaP axons, (C,C') syn4 mRNA-injected embryos have same phenotypes as syn4 morphants. (D,D') Co-injection of syn4 MO with syn4 mRNA partially rescues CaP axon defects. (E) Statistical results of CaP axon outgrowth are shown in (A–D'). For each group 60 axons from 12 embryos are scored. (F) The CaP axons of control embryos and syn4 morphants are photographed under confocal microscopy. (G) Statistical results of axon length in (F–G). The length of CaP axons is reduced in syn4 morphants (**P < 0.01, t-test). (H) the branch number of CaP axons is increased (***P < 0.001, t-test) in syn4 morphants. For each group 75 axons from 15 embryos are scored. The box regions are magnified and show in (A'–D'). Arrows indicate shortened CaP axons and abnormal branchs. Lateral views, dorsal to the top and anterior to the left in (A–D’,F). Scale bars: 100 μm.