Figure 6. Loss of KLC4 results in aberrant axon fasciculation.

(A) In wild type embryos, the most common response to self or non-self contact between axons is retraction. Two neighboring axons in a wild type embryo make contact (time 0’) and within 30 min, one of the axons has retracted. (B–C) When axons make contact in klc4^uw314 embryos, they often fasciculate instead of retracting. This happens with both self-contacts (B–C, sf) and non-self-contacts (C), nsf. All scale bars = 20 µm. (D) Fasciculations per neuron, separated by self or non-self, as well as all fasciculations combined. Wild type N=35 neurons in 4 embryos. Klc4^uw314 N=37 neurons in 5 embryos. Error bars = SEM. (E) Fasciculation length was measured from the last frame of each 2 hr imaging period. Wild type N=3 fasciculations, klc4^uw314 N=19 fasciculations. Mean with SEM displayed over individual data points. Because fasciculation events are rare in wild-type embryos and a length measurement is conditional on the event occurring, we could not apply a statistical test to assess the significance of the difference in fasciculation length.

Figure 6—video 1. A peripheral axon in a klc4^uw314 mutant embryo contacts a neighboring peripheral axon and fasciculates with it.

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Figure 6—video 2. Tight fasciculation is revealed in a klc4^uw314 mutant peripheral axon as a gap opens between the two axons as an interstitial branch forms.

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