Fig. 6

Neurobeachin Is Necessary and Sufficient in the Postsynaptic Neuron for Electrical and Chemical Synapse Formation

(A-I) Dorsal views of chimeric larvae at 6 dpf containing GFP-marked cells transplanted from an M/CoLo:GFP embryo into an unmarked host. Larvae are stained for GFP (magenta), Cx36 (yellow), and glycine receptor (GlyR, cyan). Individual Cx36 and GlyR channels are shown in neighboring panels. Arrows point to M/CoLo electrical synapses. Arrows also point to the adjacent postsynaptic side of the CoLo/CoLo synapse associated with the upper left CoLo neuron. Arrowheads point to the presynaptic side of the glycinergic synapse associated with the upper left CoLo neuron.

(A–C) Individual examples of control chimeric larvae with cells transplanted from a M/CoLo:GFP embryo into an unmarked wild-type host (wt>wt).

(D–F) Examples of chimeric larvae testing where Nbea is necessary, with cells transplanted from a nbea mutant M/CoLo:GFP embryo into an unmarked wild-type host (nbea>wt). Note the greatly diminished synapses when the nbea mutant cell is the postsynaptic neuron (D and F).

(G–I) Examples of chimeric larvae testing where Nbea is sufficient, with cells transplanted from an M/CoLo:GFP embryo into an unmarked nbea mutant host (wt>nbea). Note that synapses are rescued when the postsynaptic neuron is wild-type for Nbea (G and I).

(J–M) Quantitation of the ratio of Cx36 fluorescence at M/CoLo or GlyR fluorescence at CoLo/CoLo synapses at transplant-associated neurons compared to unassociated neurons within the same animal in wt>wt and nbea>wt chimeras (J and L) and wt>nbea chimeras (K and M). Graphs represent data as mean ± SEM. p < 0.01, p < 0.001, p < 0.0001 compared to control; ns, not significant.

Associated experimental statistics are found in Table S4.