FIGURE 1

FIGURE 1

Large and small populations of spinal motor neurons can be manipulated with the Gal4/UAS system in zebrafish. (A) Tg[mnr2b-hs:Gal4]; Tg[UAS:EGFP] larva at 5 day post-fertilization. In the Gal4 driver Tg[mnr2b-hs:Gal4], the Gal4FF transcription factor (Asakawa et al., 2008) is expressed from the bacterial artificial chromosome (BAC) transgene carrying the mnr2b locus (encoding the Mnx-type homeobox protein, which promotes motor neuron differentiation) and drives expression of a gene downstream of upstream activation sequence (UAS) in the most of the spinal motor neurons. (B) Schematic illustration of a transverse section of the middle trunk of a 5 day-old wild-type zebrafish larva, with the dorsal side up. Fast-twitch muscle and slow muscle are shown in gray and red, respectively. A CaP innervating the ventral myotome is shown in green. sc, spinal cord. nc, notochord. Illustration modified from Bello-Rojas et al. (2019). (C) Schematic illustration of a wild-type CaP innervating the ventral myotome, from lateral view. (D) Among the spinal motor neurons, CaPs (arrows) are selectively labeled in Tg[SAIG213A] Tg[UAS:EGFP] fish. Bars are 1 mm (A) and 20 μm (D).