Analysis of differentially expressed genes in the sea cucumber Apostichopus japonicus under heat stress

The high-throughput RNA-seq was applied under both 26°C and 30°C heat stress in Apostichopus japonicus, which revealed characterization of gene expression at sub-lethal and lethal limit temperature. The results will help to better understand the characteristics of heat shock response in A. japonicus. The sea cucumbers in control group were still kept at 18°C without any change, and the intestine tissue was sampled from the control group. For the heat stress experiment, sea cucumbers went through a temperature-rise process from 18°C to 26°C or to 30°C respectively, with a rate of 2°C per hour by using a heating rod. Then the water maintained at the treatment temperature, and the initial time was set with the moment when the temperature reached 26°C or 30°C. After 6 h and 48 h from initial time, the sea cucumbers 26°C treatment were sampled with intestine tissue, which was regarded as the group 26°C_6h and 26°C_48h respectively. After 6 h from initial time, the sea cucumbers 30°C treatment were sampled with intestine tissue, which was regarded as the group 30°C_6h. All the samples were quickly frozen in liquid nitrogen, and then stored at -80°C for further usage.