Differential gene expression in the intestine of sea cucumber (Apostichopus japonicus) under low and high salinity conditions

Sea cucumber, Apostichopus japonicus is a very important species for aquaculture, and its behavior and physiology can respond to the initial change in salinity. It is important to understand the molecular responses of A. japonicus when exposed to ambient changes in salinity In this study, RNA-seq provided a general overview of the gene expression profiles of the intestine of A. japonicus exposed to high salinity (SD40), normal salinity (SD30) and low salinity (SD20) environment. Sea cucumbers were acclimated in tanks containing aerated sand-filtered seawater (salinity 30%, pH 8.0) at 15 ± 0.5°C for one week before use and were fed once each day at 8:00 am during this period. The animals were then assigned randomly to three groups (20 individuals in each group). One group of sea cucumbers was maintained as the control group with normal salinity (SD30) of around 30, whereas the other two groups were kept in sea water where the salinity was gradually increased and decreased to high salinity (SD40) of around 40 and low salinity (SD20) of around 20 at a rate of 2.5 per 6 h.