Sea Anemone Genome Reveals Ancestral Eumetazoan Gene Repertoire and Genomic Organization

TLDR

Sea anemones are among the oldest eumetazoan phyla, representing a primitive lineage alongside corals, jellyfish, and hydras. Here, we report a comparative analysis of the draft genome of the emerging cnidarian model, the starlet sea anemone *Nematostella vectensis*. The *Nematostella* genome is complex, with gene repertoire, exon‑intron structure, and large‑scale linkage resembling vertebrates, implying a similarly complex eumetazoan ancestor; about 20 % of its inferred ancestral genes are novelties enriched for cell signaling, adhesion, and synaptic transmission, and these innovations appear to have been integrated with preexisting eukaryotic genes.

Abstract

Sea anemones are seemingly primitive animals that, along with corals, jellyfish, and hydras, constitute the oldest eumetazoan phylum, the Cnidaria. Here, we report a comparative analysis of the draft genome of an emerging cnidarian model, the starlet sea anemone Nematostella vectensis . The sea anemone genome is complex, with a gene repertoire, exon-intron structure, and large-scale gene linkage more similar to vertebrates than to flies or nematodes, implying that the genome of the eumetazoan ancestor was similarly complex. Nearly one-fifth of the inferred genes of the ancestor are eumetazoan novelties, which are enriched for animal functions like cell signaling, adhesion, and synaptic transmission. Analysis of diverse pathways suggests that these gene “inventions” along the lineage leading to animals were likely already well integrated with preexisting eukaryotic genes in the eumetazoan progenitor.