Fig. 1: Single-cell transcriptomics identifies Tig1 as a marker for proximal limb identity in connective tissue cells of early limb blastemas.

a UMAP embedding of single-cell transcriptomic data from connective tissue cells at 11 days postamputation¹⁹. This corresponds to an early blastema regeneration stage (8–9 cm snout-to-tail axolotls). Each dot represents a single cell; colours indicate results of Louvain clustering of single cells. b Contribution of axolotl genes to PC1. Genes are presented as dots and are ordered based on their contribution to PC1. Genes associated with the proximal (red) and distal (blue) axes, or with cell adhesion (yellow) are indicated. c Gene expression for genes of the proximal-distal axis are shown as feature on top of the UMAP embedding. Encircled genes are used to calculate a proximal and distal score (see d). d Distal (left) and proximal (right) scores were calculated for each cell and visualised on the UMAP embedding. Scores were combined to obtain proximal-distal identity assignments (centre) for each cell as indicated on the embedding. e Volcano plot visualisation of genes that are differentially expressed between the 100 most proximal and the 100 most distal cells identified by the scoring in d. Relevant proximal (red) and distal (blue) genes are highlighted. P values (Wilcoxon rank-sum test) are shown as −Log₁₀ and the p value cutoff is 0.0001 (horizontal dotted line) and the fold change (FC) cutoffs are 0.4 and −0.4 (vertical dotted lines).