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. 2022 Apr 8;11:e72723. doi: 10.7554/eLife.72723

Figure 1. RA is both produced and active in the nascent RP.

(A) Schematic illustration of the metabolic and signaling pathways of RA. (B–M) Expression patterns of genes participating in RA synthesis and metabolism, both at early and advanced NC stages [E2 (27 ss) and E3 (35 ss), respectively], and at the RP stage (E4). ISH for Raldh2/Aldh1a2 (B–D), Cyp1B1 (E–G), Cyp26A1 (H–J), and CRABP1 (K–M). Images were taken at the level of somites 25–27. (N-O’) RA activity in the NT at NC and RP stages, indicated by the presence of destabilized GFP (d2EGFP) driven under the control of a RARE element. Embryos were electroporated at E2.5 (28 ss) along with control RFP to monitor efficiency of transfection, and analyzed 12 hr (N-N’, at 35 ss) or 48 hr (O-O’, at E4) later. RARE activity was evident in the dorsal NT of NC-stage embryos (N = 8/8), and RP-stage embryos (N = 7/7). Images were taken at the level of somites 25–27. Abbreviations, EpS, epithelial somite, No, notochord, NT, neural tube, DM, dermomyotome, Scl, sclerotome, DRG, dorsal root ganglion. Scale bar, 50 μm.

Figure 1.

Figure 1—figure supplement 1. Expression patterns of selected genes from a comparative RNA-seq analysis between NC and RP stages.

Figure 1—figure supplement 1.

(A–C) Heat maps depicting the differential expression patterns of genes involved in RA (A), BMP (B) or Wnt (C) pathways, adapted from an RNA-seq analysis performed by Ofek et al. (Ofek et al., 2021) on premigratory NC (experimental triplicates NC1, NC2, NC3) and RP cells (experimental triplicates RP1, RP2, RP3). Genes discussed in the present study were marked by an asterisk.
Figure 1—figure supplement 2. Expression of RA receptors in the dorsal NT at the RP stage.

Figure 1—figure supplement 2.

(A–E) ISH showing expression patterns of RA receptors at the RP stage (E4). [See also (Diez del Corral et al., 2003), for whole-embryo ISH at the NC stage]. Images were taken at somite levels 24–26. (A) Expression of RARα is ubiquitous, including the dorsal NT (asterisk). (B) RARβis expressed in the NT, including the dorsal domain (asterisk). (C) No significant expression of RARγ in the NT. (D) RXRαis expressed throughout the NT, except for the dorsal domain (delineated by dashed lines). (E) Expression of RXRγat the RP stage appears in the entire NT (asterisk dorsal to the RP) and in NC derivatives such as the DRG. Abbreviations, DM, dermomyotome, DRG, dorsal root ganglion, NT, neural tube, No, notochord, Scl, sclerotome. Scale bar, 50 μm.