Fig. 1

The Neuromuscular Connection between mnr2b-ABNs and the Lateral Rectus Muscle

(A) Structure of Tg[mnr2b-hs:Gal4] and Tg[actc1b:tdT-chrnd]. The hsp70l promoter-Gal4FF-polyA-Km^r cassette was inserted downstream of the 5′ UTR of mnr2b. tdT-chrnd is driven by the actc1b-hsp70l tandem promoter.

(B) Lateral view of Tg[mnr2b-hs:Gal4]; Tg[UAS:GFP] larvae at 5 dpf.

(C) Axonal projection of the eGFP-labeled abducens motor neurons. The dorsal cell cluster was omitted for clarity of the projections.

(D–F) Dorsal (D), lateral (E), and rear (F) views of the eGFP cell clusters. The brackets indicate the dorsal cell cluster.

(G) Dorsal view of lateral rectus muscles (LR) at 5 dpf.

(H) Gathered (double arrowhead) and scattered (bracket) AChRs labeled by tdT-chrnd on the right LR in (G).

(I) Lateral rectus muscle of Tg[mnr2b-hs:Gal4]; Tg[UAS:V2V]; Tg[actc1b:tdT-chrnd] larva at 5 dpf.

(J) The fluorescence intensities of the gathered tdT-chrnd and associated eGFP signals measured for each inner and outer halves of the muscle. N = 10 neuromuscular connections from five animals. ^∗p = 0.024. ns, not significant.

In (G)–(J), rostral is to the top. Scale bars indicate 500 bp in (A), 250 μm in (B), 50 μm in (C)–(F), (H), and (I), and 20 μm in (J). The vertical dashed lines indicate the midline. Hereafter, double white and black arrowheads indicate the presumptive initial contact sites with the lateral rectus muscle, r5, and r6, respectively, unless otherwise stated. D, dorsal; LL, left-lateral; R, rostral.