Diversity And Phylogeny Analysis Of Toxicity And Development Related Gene Families Based On Genome Sequences Of Scyphozoans

This study sequenced,assembled and annotated the first draft genomes of Rhopilema esculentum,Cassiopea andromeda and Mastigias papua(Cnidaria: Scyphozoa),also constructed cluster analysis of gene families to understand species specificity and homology.This study focused on the diversity and phylogeny of essential regulators Hox,POU domain genes which are associated with jellyfish sense and nerve.Genetic analysis revealed that Hox and POU gene families have obvious interspecies differences in the phylum Cnidaria.Firstly,this study supported the hypothesis that there is no central Hox gene in cnidarians,and it was found that there is a partial deletion of anterior Hox gene for Scyphozoa and H.vulgaris.As for ParaHox in cnidarians,GSX and XLOX/CDX genes were all found in C.andromeda and R.esculentum,though M.papua possessed only GSX gene.Secondly,C.andromeda,R.esculentum and N.vectensis were found to have all 4 classes of POU genes while M.papua,A.aurita and H.vulgaris had only 2 POU gene classes respectively.Among the cnidarians analyzed in this study,C.andromeda had the highest levels of nucleotide polymorphisms of the POU-1,-6 subtypes;C.andromeda with higher diversity of POU-2/3/5 domain gene class was closer to the corals and sea anemones than other scyphozoans.In addition,the parallels and differences of the adhesive-related proteins between three scyphozoans and H.vulgaris were summarized: C.andromeda was predicted to have unique adhesiverelated lectins(Rhamnose-binding lectin protein)and ferric-chelate reductase which M.papua,R.esculentum didn't possess.In conclusion,greater numbers of POU encoding genes and more complex POU isoforms maybe one of the key genetic factors that contribute to the upside-down,"sleep-like" unique state of C.andromeda.The result that adhesive-related lectin proteins and reductase encoding genes remained in C.andromeda was another potential genetic factor.In order to understand the components of venom proteins in jellyfish scyphozoans and explore the phylogeny of metazoan toxins,we used all known toxin-related domains and motifs of non-Bilateria Metazoans(Radiata)to predict the potential toxic proteins/polypeptides in the genome comprehensively.The result indicated that phospholipase and lipase are the most abundant types of venom protein,followed by enzyme inhibitors,while the relatively small venom protein types are venom allergen,neurotoxin and cytolysin.About half of the toxic protein families in Scyphozoa were common to all classes of Cnidaria.Secondly,we found that some common domains are related to toxins,which were predicted to be potential venom cofactor of jellyfish,such as SPRY,Collagen-like protein,Growth factor-like domains.Thirdly,it was also found that the neurotoxin components of Medusozoa and Anthozoa are quite different.A number of neurotoxin types had been lost in Medusozoa,such as Spider toxin,Anenome neurotoxin(including Shk-like neurotoxin),Latrotoxin,SCRiPs,Ionic channel ASIC inhibitor,Ergotoxin,Epidermal growth factor-like protein PDGF / VEGF,which were only found in anthozoans.Fourthly,various toxin families of Cnidaria(such as Metallopeptidase family M12 B Reprolysin,Cysteine-rich secretory protein,C-type lectin,etc.)were preserved in snakes or other poisonous animals.In addition,there was the first discovery of several toxin-related domains in Scyphozoa: Hyaluronidase,Oxidoreductase,Multicopper oxidase as potential venom cofactors;Phospholipase B,TCTP,APHC1(TRPV1 inhibitor)homologue which were thought to be limited to Anthozoa.