Effects and transcriptional responses in the hepatopancreas of red claw crayfish Cherax quadricarinatus under cold stress.

The red claw crayfish, Cherax quadricarinatus, is an economically important freshwater crustacean that cannot tolerate low temperature, which diminishes survival via unknown mechanisms. Herein, physiological regulation of C. quadricarinatus was investigated following exposure to low temperature stress at 9 ±â€¯2 °C for 4 weeks. Hepatopancreas tissue was tested for nonspecific enzyme activity, histological structure, and transcriptome sequencing analyses. The results showed that the activities of nonspecific enzymes were inhibited following low temperature stress. Ultrastructural observation revealed that the hepatopancreas structure was oxidatively damaged at low temperature, with numerous autophagic vesicles visible. Apoptosis in the hepatopancreas was significantly increased in the cold stress group, indicating diminished function. Transcriptome sequencing identified 2615 differentially expressed genes (DEGs) following low temperature stress, of which 1147 and 1468 were up- and down-regulated, respectively. Functional analysis of DEGs indicated involvement in substance metabolism, antioxidant defences, signal transduction, and immune responses. Therefore, chronic cold stress can suppress metabolism and cause oxidative damage and immune deficiency in crayfish. The findings provide fundamental molecular information for further study of the regulatory mechanisms of cold tolerance in red claw crayfish.