Fig. 4

Knockdown of Etv5b results in axon defects due to motoneuronal reduction of Smn.

(a,b) Z-projections of Znp1 stained motor axons on one side of an embryo after injection of control MO (a) and etv5b MO (b). Scale bar: 50 µm. Arrowheads mark different defects. (c) Quantification of axon defects. Normal, mild, moderate and severe axon morphology in control MO and etv5b MO injected embryos. N = 2 experiments (control MO, in total of 17 embryos) and 5 experiments (etv5b MO, in total of 42 embryos), n = number of axons analyzed. Significance is determined by comparing the occurrences of moderate and severe defects. Exact values in percentages of affected axons are (mean ± SD): 71 ± 7.8 (control MO, normal, 23 ± 10.6 (control MO, mild), 5 ± 2.1 (control MO, moderate), 1 ± 0.7 (control MO, severe), 38 ± 12.2 (etv5b MO, normal), 24 ± 4.4 (etv5b MO, mild), 21 ± 8.5 (etv5b MO, moderate) and 17 ± 5.8 (etv5b MO severe), p = 0.001 with unpaired Student’s t-test. (d,e) Z-projection of Znp1 stained motor axons on one side of control (d) and pmnx1:mCherry-Smn (e) embryos injected with etv5b MO. mCherry signal is shown below the Znp1 panel. (f) Quantification of axon morphology phenotypes in control and pmnx1:mCherry-Smn (mCh-S) embryos injected with etv5b MO. N = 3 experiments, n = number of axons analyzed in total of 22 (control MO) and 20 embryos (etv5b MO). Significance is determined by comparing the occurrences of moderate and severe defects. Exact values in percentages of affected axons are (mean ± SD): 32 ± 11.3 (control etv5b MO normal), 24 ± 5.9 (control etv5b MO mild), 28 ± 7 (control etv5b MO moderate), 16 ± 1.4 (control etv5b MO severe), 67 ± 9 (mCh-S etv5b MO normal), 21 ± 8.3 (mCh-S etv5b MO mild), 11 ± 0.8 (mCh-S etv5b MO moderate), 2 ± 0.9 (mCh-S etv5b MO severe), p = 0.009 with unpaired Student’s t-test.