Fig. 5.

Fig. 5.

Loss of Nrxn3 impacts pre- and postsynapse size and Ca_V1.3 channel localization in lateral-line hair cells. (A-D) There is a significant increase in the area of paired (A,C) but not unpaired (B,D) pre- and postsynapses in nrxn3a; nrxn3b mutants compared with wild-type controls. (E-H) Confocal images of mature neuromasts from wild-type controls (E,F) and nrxn3a; nrxn3b mutants (G,H). CTBP labels presynapses with Ca_V1.3 (E,G) and MAGUK labels postsynapses with Ca_V1.3 (F,H). The boxed areas (magnified on right) show three examples of individual synapses. Hair cells in A-D were visualized with an Otoferlin or Parvalbumin co-label (not shown). (I-L) Quantification shows no change in the number of Ca_V1.3-CTBP paired puncta per hair cell in nrxn3a; nrxn3b mutants (I). However, there are significantly fewer Ca_V1.3-MAGUK paired puncta per hair cell in nrxn3a; nrxn3b mutants (J). The area (K) but not the average intensity (L) of Ca_V1.3 puncta associated with CTBP puncta is significantly lower in nrxn3a; nrxn3b mutants. n=10 wild-type and 11 nrxn3a; nrxn3b mutant neuromasts in A-D,I,K,L and n=10 wild-type and 8 nrxn3a; nrxn3b mutant neuromasts in J. Images and quantification are from larvae at 5 dpf. An unpaired two-tailed t-test was used in A-D and I-L. ns, P>0.05; **P<0.01; ****P<0.0001. Data are mean±s.e.m. Scale bars: 5 µm (E-H); 1 µm (E-H, insets).