Fig. 1: Distinct muscle cell types in the sea anemone Nematostella vectensis are identified from single-cell sequencing data. | Nature Communications

Fig. 1: Distinct muscle cell types in the sea anemone Nematostella vectensis are identified from single-cell sequencing data.

From: Muscle cell-type diversification is driven by bHLH transcription factor expansion and extensive effector gene duplications

Fig. 1: Distinct muscle cell types in the sea anemone Nematostella vectensis are identified from single-cell sequencing data.The alternative text for this image may have been generated using AI.

a Muscle cell relationships in vertebrates (Bilateria) and the sea anemone (Cnidaria). Two ancestral cell types corresponding to a fast (purple circles) and slow (green circles) contracting phenotype derive from the mesoderm in vertebrates. Muscles can arise from both cell layers in the diploblastic sea anemone, but their contractile properties are undescribed (gray). Both the intra- and interspecies evolutionary relationships of these muscle types are unclear. Ec: ectoderm, Me: mesoderm, En: endoderm, Em: endomesoderm b Schematic view of Nematostella muscle systems: tentacle and mesentery anatomy are illustrated schematically in cross section with the positions of the muscles indicated; blue: tentacle retractor (TR); light green: circular muscle (CM); dark green: parietal muscle (PM); red: mesentery retractor (MR); ocher: the intermuscular membrane (ImM) c Heatmap of differentially expressed genes of the mesentery-derived bulk transcriptomes. Average gene expression from differentially expressed genes with less than a twofold change of expression between library source (mCherry negative non-muscle, two replicates, vs. mCherry+ mesentery retractor muscle cells, two replicates) is imaged. The indicated muscle-related genes are upregulated in the muscle-cell libraries. d Heat map of differentially expressed genes across eight cell populations identified by single-cell RNAseq. The same muscle-related genes are detected in the retractor (1) cluster. Cell clusters carried forward as the muscle subset are indicated in the box. d′ Dimensional reduction cell plot (UMAP) of the full dataset showing expression of the muscle marker myosin heavy chain (myhc-st) in the retractor (1) as well as the gastrodermis (2). e UMAP cell plot of the muscle subset annotated according to cluster identity. Four differentiated muscle cell clusters are identifiable and color-coded as in part (b). Differentiated muscle cells represent approximately one-quarter of the data subset (pie chart). e′ Expression profiles of markers indicative of the retractor muscles (melc4), the bodywall muscles (myph-like8), and the intermuscular membrane (melc3), with rainbow expression profile: gray: no expression; blue: low; red: high.

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