Fig. 1

Pax3 expression is recapitulated by the activity of 2 CRMs.

(A, A′) At E9.5, Pax3 expression correlates with cells labeled by YFP in Pax3^Cre/+;Rosa26-YFP mouse embryos (n = 2). However between E10.5 (B) (n = 2) and E11.75 (C) (n = 2), cells derived from the Pax3 lineage are found in the both the dorsal and ventral neural tube of Pax3^Cre/+;Rosa26-GFP/YFP mouse embryos. In the ventral neural tube, clusters of isolated cells (asterisk in B and C) and a domain spanning 3–4 cells adjacent to the Pax3 ventral boundary (B′ and arrows in B and C) is observed. (D) This domain of transgene expression encompasses, but is not limited to, Evx1 expressing ventral interneurons at E11.75 (n = 2). (E, E′). Consistent with the labeling of interneurons at E11.75, embryos assessed at E9.75 exhibit a boundary of Pax3 lineage opposed to the dorsal limit of the Nkx6.1 domain (n = 3). (F) Comparative genomic analysis of the Pax3 locus reveals 6 CNEs within the 4^th intron of the gene. (G) Pax3a mRNA is first detected in the developing midbrain, hindbrain and intermediate regions of the posterior neural plate (pnp) of zebrafish embryos at 10 hpf. (H) By 12 hpf, transcription is limited to the lateral neural plate (lnp) posteriorly. (I) At 24 hpf, pax3a is highly expressed in the midbrain, hindbrain and progenitors within the dorsal spinal cord (dP), as shown in (I′). (J) Transcription is rapidly downregulated in the spinal cord after 24 hpf and is not detectable at 48 hpf. (K–L) Pax3/7 protein, visualised with the DP312 antibody, is also restricted to the intermediate and lateral regions of the neural plate at 10 hpf and the dorsal half of the spinal cord at 24 hpf. (M–N) Profile views of CNE1::Citrine transient transgenic embryos at 10 and 12 hpf showing enhancer activity in the tail bud (bd) and lateral neural plate (M) (n = 25/27), then within dorsal neural progenitors (N) (n = 19/22). (O, O′) At 24 hpf, CNE1::Citrine transient transgenics recapitulate pax3a expression across the AP axis of the CNS and the DV axis of the spinal cord. (P–R′) CNE3 is active in the neural plate and tail bud at 10 and 12 hpf (n = 10/10, n = 7/7), however embryos rarely exhibit labeling of Pax3/7 expressing progenitors within the dorsal spinal cord at 24 hpf (n = 5/48).