Differential gene expression between normoxic and hypoxic conditions in the moon jellyfish Aurelia coerulea (Scorrano)

Abstract

Compared with other marine organisms, jellyfish are tolerant to hypoxia and frequently occur in minimum oxygen zones. However, the molecular mechanisms underlying this tolerance remain unknown. This study investigated the molecular mechanisms responsible for hypoxia tolerance in Aurelia coerulea by cultivating them in an enclosed cultivation system under hypoxic and oxygen-saturated conditions for 18 h, followed by transcriptome-wide RNA sequencing (RNA-Seq). Differential expression analysis indicated that 417 unigenes in medusae and 202 unigenes in polyps were differentially expressed between hypoxic and oxygen-saturated conditions. These differentially expressed genes were mainly involved in the metabolic process and catalytic activity and enriched in protein digestion and absorption, Hypoxia-Inducible Factor-1 (HIF-1) signalling and oxidative phosphorylation pathways. Some of these specific transcripts in the enriched pathways were validated by quantitative real-time polymerase chain reaction. These results may provide mechanistic insights into the hypoxic tolerance of lower marine invertebrates that absorb oxygen directly from the water.