Box, stalked, and upside-down? Draft genomes from diverse jellyfish (Cnidaria, Acraspeda) lineages: Alatina alata (Cubozoa), Calvadosia cruxmelitensis (Staurozoa), and Cassiopea xamachana (Scyphozoa)

Abstract

Background Anthozoa, Endocnidozoa, and Medusozoa are the 3 major clades of Cnidaria. Medusozoa is further divided into 4 clades, Hydrozoa, Staurozoa, Cubozoa, and Scyphozoa—the latter 3 lineages make up the clade Acraspeda. Acraspeda encompasses extraordinary diversity in terms of life history, numerous nuisance species, taxa with complex eyes rivaling other animals, and some of the most venomous organisms on the planet. Genomes have recently become available within Scyphozoa and Cubozoa, but there are currently no published genomes within Staurozoa and Cubozoa. Findings Here we present 3 new draft genomes of Calvadosia cruxmelitensis (Staurozoa), Alatina alata (Cubozoa), and Cassiopea xamachana (Scyphozoa) for which we provide a preliminary orthology analysis that includes an inventory of their respective venom-related genes. Additionally, we identify synteny between POU and Hox genes that had previously been reported in a hydrozoan, suggesting this linkage is highly conserved, possibly dating back to at least the last common ancestor of Medusozoa, yet likely independent of vertebrate POU-Hox linkages. Conclusions These draft genomes provide a valuable resource for studying the evolutionary history and biology of these extraordinary animals, and for identifying genomic features underlying venom, vision, and life history traits in Acraspeda.

Cassiosomes are stinging-cell structures in the mucus of the upside-down jellyfish Cassiopea xamachana

“…Amplification of the qPCR gene target was observed for both C. xamachana tissue and cassiosome samples using primers for the CrTX/CaTX gene, herein named CassTX-C (see Data Availability section below). Conversely, failure to amplify the target in non-Cassiopea medusozoans used in this study (despite reports of CrTX/CaTX genes documented in both Aurelia sp and A. alata 14,39 ) validates the specificity of our primers to a C. xamachana-derived gene target, indicating that cassiosomes originate in Cassiopea medusae.…”

“…1c-f). A shotgun proteomic analysis identified three isoforms of the target toxin family encoded in the C. xamachana genome 14 , which we call CassTX-A, CassTX-B and CassTX-C ( Fig. 7).…”

“…Another indirect stinging mechanism is through mucus, such as in medusae of the upside-down mangrove jellyfish Cassiopea xamachana Bigelow 1892 (Class Scyphozoa; Order Rhizostomeae), an emerging cnidarian model for its relevance to the study of coevolution as well as symbiosis-driven development (reviewed in ref. 14 ). Additionally, the ubiquity of Cassiopea medusae in healthy mangroves has earned the upside-down jellyfish status as a potential bioindicator species for coastal management and conservation efforts 15,16 .…”

“…We document the presence of cassiosomes in five species spanning four families of the order Rhizostomeae, while also confirming their absence in the moon jellyfish Aurelia (Semaeostomeae), a representative of the sister lineage, and discuss the possibility of a single evolutionary event behind this envenomation strategy which, to our knowledge, is unique. Despite the growing body of work on C. xamachana from an organismal biology perspective 14,26 , this study is the first to directly investigate stinging properties of the mucus of this jellyfish and the potential ecological and evolutionary relevance.…”

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.…”