Comparative transcriptome analysis of gill tissue response to hypoxia stress in the Chinese mitten crab (Eriocheir sinensis)

Crustaceans often encounter the occurrence of various hypoxic situations, and in order to cope with this situation, they have evolved a series of antioxidant defenses against hypoxic stress. The present study was conducted to investigate the physiological and molecular regulation of hypoxic stress in the Chinese mitten crab (Eriocheir sinensis). We used the method of reducing dissolved oxygen in water to treat the juvenile E. sinensis with hypoxia. The results showed that total antioxidant capacity, superoxide dismutase, catalase and malondialdehyde contents in the gills of juvenile crabs were significantly elevated under hypoxia. In addition, gill tissues from normoxic control (NC), hypoxia-sensitive (HS) and hypoxia-tolerant (HT) groups were analysed using transcriptomic sequencing. The results revealed that 2124, 2946 and 2309 differentially expressed genes (DEGs) were found in NC vs. HS, NC vs. HT and HS vs. HT, respectively. The analysis of KEGG pathway enrichment indicated DEGs were predominantly enriched in oxidative phosphorylation, adipocytokine signaling pathway, and protein processing in endoplasmic reticulum in HS vs. HT. Enrichment of the MAPK signaling pathway, apoptosis, glucagon signaling pathway, and arachidonic acid metabolism was also found in the comparisons of NC vs. HS and NC vs. HT. The DEGs in these pathways may play a key role in gill tolerance to hypoxia. These results provide new insights and references for the oxidative defense and adaptive regulatory mechanisms of gill tissues of juvenile E. sinensis in response to hypoxic stress.