Acute hypoxia and reoxygenation induces oxidative stress, glycometabolism, and oxygen transport change in red swamp crayfish (Procambarus clarkii): Application of transcriptome profiling in assessment of hypoxia

Red swamp crayfish (Procambarus clarkii), an economically and ecologically important crustacean, frequently encounter hypoxic environments in burrows or aquatic habitats. However, hepatopancreas oxidative stress and molecular regulatory network under hypoxia in crayfish has not been clearly established. To determine oxidative stress changes during hypoxia/reoxygenation in crayfish, we assessed the enzymatic activities of CAT, SOD, GST, and GPx as well as the hepatopancreas mRNA levels of Cu/Zn-sod, cat, Mu-gst, and gpx1. The mRNA levels of the aforementioned genes and activity of the enzyme increased gradually and peaked at 6.5 h of hypoxic stress (1.0 ± 0.1 mg/L) and then dropped during reoxygenation (7.0 ± 0.2 mg/L), suggesting that they protect from oxidative stress. Hepatopancreas transcriptomic analysis of changes in key genes and regulatory networks in response to hypoxia identified 4643 DEGs (differentially expressed genes), of which 2012 were upregulated, whereas 2631 downregulated. These genes are enriched in signaling cascades linked to glucose metabolism (e.g., glycolysis/gluconeogenesis, AMPK, and insulin signaling pathways) as well as oxygen transport (e.g., HIF-1, MAPK and PI3K-Akt signaling pathways). Genes associated with glucose metabolism (e.g., gapdh, pyk, and pck) and oxygen transport (e.g., egln, gapdh, and pdk1) were also identified. Our findings indicate that the red swamp crayfish may utilize "glycolysis/gluconeogenesis" to maintain responsive and active functions and "HIF-1″ to obtain more oxygen under hypoxia.