The complete mitogenome of ghost jellyfish Cyanea nozakii (Cnidaria, Semaeostomeae, Cyaneidae)

Characterization and phylogenetic analysis of the complete mitochondrial genome of Cotylorhiza tuberculata assembled using next-generation sequencing

In this study, the complete mitochondrial genome (mitogenome) of Cotylorhiza tuberculata (Scyphozoa; Rhizostomeae; Cepheidae) was assembled by the next-generation sequencing data. The complete mitogenome spanned 16,590 bp and contained 14 protein-coding genes, two transfer RNA genes, and two ribosomal RNA genes. Total AT% content was 67.7%, comprising A 30.22%, C 16.16%, G 17.05%, and T 36.56%. The gene arrangement exhibited consistency with the known mitogenomes of other jellyfish species. Furthermore, the phylogenetic relationship of C. tuberculata was investigated based on analysis of the 13 common protein-coding genes. Results indicated a close relationship between C. tuberculata and both Cassiopea xamachana and Cassiopea andromeda. These findings provide a valuable reference for advancing understanding of the phylogenetic relationships, taxonomic classification, and phylogeography of jellyfish species.

Complete mitochondrial genome of Mastigias papua (Scyphozoa: Rhizostomeae: Mastigiidae) based on next-generation sequencing and phylogenetic analysis

We assembled the complete mitochondrial genome (mitogenome) of Mastigias papua (Scyphozoa: Rhizostomeae: Mastigiidae) by the data generated from the next-generation sequencing platform. The complete mitogenome of M. papua was 16,560 bp in length, containing 14 protein-coding genes, two transfer RNA genes, and two ribosomal RNA genes. The base compositions were A 30.65%, C 15.16%, G 16.34%, and T 37.86%, with a gene arrangement similar to the mitogenomes derived from other representatives of Scyphozoa. Based on the 13 common protein-coding genes of 16 species within Scyphozoa, we constructed the phylogenetic tree and found that M. papua has a close relationship with Cassiopea andromeda and Cassiopea xamachana. All these species belong to an order of jellyfish Rhizostomeae, which have similar morphological characteristics. This is agreement with the conclusion we got by the phylogenetic relationship analysis using molecular data. This research has practical implications for advancing understanding of the phylogenetic relationships, taxonomic classifications, and phylogeography within Scyphozoa.

Evaluation of the complete nuclear rDNA unit sequence of the jellyfish Cyanea nozakii Kishinouye (Scyphozoa: Semaeostomeae) for molecular discrimination

The harmful jellyfish Cyanea nozakii Kishinouye has frequently occurred on Korean coasts, and its blooms have caused serious ecological and economic damages. DNA sequences of the C. nozakii for molecular detection and discrimination are relatively scarce. In this study, we determined the complete sequence of a single unit of tandemly repeated ribosomal DNA (rDNA) of the Korean C. nozakii and characterized the molecular features of the rDNA. The complete rDNA contained 8,003 bp (48.4% GC) with the same gene arrangement (18S, ITS1, 5.8S, ITS2, 28S, and IGS) to the typical eukaryotes. Dot plot analysis showed that the coding regions (18S, 5.8S, and 28S) were highly conserved, while the non-coding regions (ITS1, ITS2, and IGS) were more variable and parsimony-informative. The IGS contained a putative transcription termination signal (poly(T) tract) and four repeats of block minisatellites. Phylogenetic analyses using 18S and 28S rDNA revealed well-resolved relationships of C. nozakii within the order Semaeostomeae, separating it from other Cyanea species. The complete rDNA sequence provides various options for the selection of jellyfish taxonomic markers and may be useful for discriminating between species of C. nozakii and phylogeny reconstruction with close relatives.