AUTHOR=Xia Wangxiao , Li Haorong , Cheng Wenmin , Li Honghui , Mi Yajing , Gou Xingchun , Liu Yaowen 

TITLE=High-Quality Genome Assembly of Chrysaora quinquecirrha Provides Insights Into the Adaptive Evolution of Jellyfish

JOURNAL=Frontiers in Genetics

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2020.00535

DOI=10.3389/fgene.2020.00535

ISSN=1664-8021

ABSTRACT=<p>Jellyfish, such as <italic>Chrysaora quinquecirrha</italic>, hold an important evolutionary position and have great ecological value. However, limited genomic resources are currently available for studying their basic genetic and development processes. Here, we <italic>de novo</italic> assembled the first high-quality reference genome of <italic>C. quinquecirrha</italic>, and successfully annotated 21,606 protein-coding genes. Codon usage analysis identified the frequent use of low-GC-content codons during protein-coding gene translation. Analysis of the relative evolution rate indicated that jellyfish had a faster evolution rate than sea anemones but slower rate than the species in Hydra. Phylogenetic analysis with two other species of jellyfish indicated that <italic>Aurelia aurita</italic> and <italic>Nemopilema nomurai</italic> have a closer relationship with each other than with <italic>C. quinquecirrha</italic>, with divergence from their common ancestor occurring ≈475.7 million years ago. Our study not only showed the genomic characteristics and molecular adaptive evolution of <italic>C. quinquecirrha</italic>, but also provides valuable genomic resources for further study on complex developmental processes and environmental adaptations.</p>