The draft genome of Actinia tenebrosa reveals insights into toxin evolution

Abstract

Sea anemones have a wide array of toxic compounds (peptide toxins found in their venom) which have potential uses as therapeutics. To date, the majority of studies characterizing toxins in sea anemones have been restricted to species from the superfamily, Actinioidea. No highly complete draft genomes are currently available for this superfamily, however, highlighting our limited understanding of the genes encoding toxins in this important group. Here we have sequenced, assembled, and annotated a draft genome for Actinia tenebrosa. The genome is estimated to be approximately 255 megabases, with 31,556 protein‐coding genes. Quality metrics revealed that this draft genome matches the quality and completeness of other model cnidarian genomes, including Nematostella, Hydra, and Acropora. Phylogenomic analyses revealed strong conservation of the Cnidaria and Hexacorallia core‐gene set. However, we found that lineage‐specific gene families have undergone significant expansion events compared with shared gene families. Enrichment analysis performed for both gene ontologies, and protein domains revealed that genes encoding toxins contribute to a significant proportion of the lineage‐specific genes and gene families. The results make clear that the draft genome of A. tenebrosa will provide insight into the evolution of toxins and lineage‐specific genes, and provide an important resource for the discovery of novel biological compounds.

Transcriptomic Analysis of Four Cerianthid (Cnidaria, Ceriantharia) Venoms

“…Because the phylogenetic placement of subclass Ceriantharia remains unclear, it is difficult to interpret the evolutionary context of their venom profile within Anthozoa. For instance, if Ceriantharia is sister to the Hexacorallia, that suggests that the expansion of neuropeptide toxins occurred after the divergence of Ceriantharia, possibly through extensive gene duplications [ 52 , 130 , 135 ]. Neurotoxins in sea anemones are important because they are sessile animals, and may be critical to deterring predators [ 136 ].…”

Many but not all lineage-specific genes can be explained by homology detection failure

“…Our approach allows us to determine whether a particular lineage-specific gene is attributable to homology detection failure, and our approach is generalizable to a wide range of taxa, beyond the well-studied clades where synteny analysis can be used. We expect it to be useful in the wide variety of studies that aim to identify "new" genes that may underlie the evolution of morphological, behavioral, and other novel traits [7,[45][46][47][48][49]]. An implementation of our method is freely available as source code at github.com/caraweisman/abSENSE, and as a web server at eddylab.org/abSENSE.…”

Characterising Functional Venom Profiles of Anthozoans and Medusozoans within Their Ecological Context

“…The diminishing cost and technological advances in sequencing technologies will result in more 'omics' datasets for venomous taxa becoming available in coming years, highlighted by the recent publication of multiple cnidarian genomes [118,[123][124][125][126][127]. These genomic data represent a rich resource for comparative studies and the elucidation of venom evolution.…”