Fig. 1: soxC expression and blastema formation.

a Enchytraeus japonensis grows to about 10 mm in length and reproduces asexually by fragmentation approximately every 2 weeks. b Workflow of transcriptomic analyses during regeneration. Intact worms were amputated into 3 fragments (blastema-poor group) or 8 fragments (blastema-rich group). c Venn diagrams depicting selectively upregulated contigs in regenerating animals (blastema-poor and blastema-rich groups) compared with that of intact animals. d Sequential filters to select upregulated contigs in regenerating worms. We selected the genes that showed higher upregulation in the blastema-rich than in the blastema-poor group based on the FPKM value (>10). e Expression level of soxC during regeneration. soxC was upregulated at 2, 6, and 24 hpa. n = 5 for intact animals and for each time point. Error bars indicate the standard error of the mean (S.E.M.). f, g soxC expression during blastema formation at 0, 1, 3, 5, 8, and 24 hpa in horizontal sections (f) and sagittal sections (g). The sense controls and their diagrams are shown at the top. in, intestine; bw, body wall; se, septa; vn, ventral nerve cord. Dashed lines indicate amputation sites. f’ f” f”’ Magnified view of the boxed areas in (f) (1 hpa, arrowhead (f’); 3 hpa, arrowhead (f”); 5 hpa, arrowhead (f”’)). h Quantification of soxC-expressing areas in the anterior blastema of regenerating worms at 0 hpa (n = 11), 3 hpa (n = 10), 8 hpa (n = 12) and 24 hpa (n = 12). Data was combined from three independent experiments. The central lines and the error bars indicate the mean and standard deviation (SD), respectively. *p < 0.05, **p < 0.01, ***p < 0.001 (Dunnett’s test) (e, h). Scale bars represent 100 µm (f, g) and 20 µm (f’, f”, f”’). Source data are provided as a Source Data file. A: anterior, P: posterior, D: dorsal, V: ventral (f, g).