Fig. 4

Branchiostoma lanceolatum vPNS candidate genes identification by RNA-seq analysis on explants. A Schematic representation of animal blastomeres explantation of B. lanceolatum and treatments for DGE analysis. Animal blastomeres are indicated in yellow at the eight-cell stage. B Quantification of significantly (p-value <0.05 calculated by DESeq2) differentially expressed genes (in percentage of the total gene number which is 27,228 genes) from DGE analysis. For each RNA-seq experiment, upregulated genes are indicated in green and downregulated genes in red in the histograms. C Differential gene expression of vPNS genes. Log2 fold change of known (yellow backdrop) or candidate (blue backdrop) vPNS genes are shown for samples treated with BMP4 (light blue to dark blue histograms for early to late stages respectively) or BMP4+DAPT (pink and purple histograms for mid and late neurula stages respectively) compared to control levels. D–O In situ hybridization at selected developmental stages for B. lanceolatum candidate genes identified from our RNA-seq data and expressed in the vPNS: Wnt11 (D), Bmper (E), Lbx1/2 (F), Gata4/5/6 (G), Gata1/2/3 (H), Znf-like (I), Insm (K), Nhlh (K), BLAG19000137 (L), Myt1 (M), Slc6a7/9.a (N) and Brsk (O). Genes expressed in the ventral neurogenic field are represented by a blue circle and genes expressed in ESNs by a purple circle. Embryos are shown in lateral view with dorsal to the top and anterior to the left. Scale bar: 50 μm