A proteomics of gills approach to understanding salinity adaptation of Scylla paramamosain

Scylla paramamosain (Crustacea) is a commercially important euryhaline species distributed along the coast of southern China and other Indo-Pacific countries. However, a sudden variation in salinity will cause injury or even death to S. paramamosain. In this paper, we simulated a sudden decrease in salinity due to heavy precipitation in crab ponds. Comparison of gill microstructures of individuals in the control group and decreased salinity group showed gills became shorter and thicker, while the top of the filaments became swollen and then returned to normal after 120 h. A total of 3962 proteins were identified by proteomic sequencing of gills after 120 h under conditions of decreased salinity. 845 proteins were differentially expressed: 371 up-regulated and 474 down-regulated. Of the enriched KEGG pathways, 20 were up-regulated and 14 were down-regulation (P < 0.05). Among the significantly enriched up-regulated pathways, six were associated with amino acid metabolism and three were associated with Na+-K+-ATPase enzymatic activities. Pathways associated with redox metabolism and energy metabolism were identified. These results showed that in response to a decrease in salinity, S. paramamosain could adapt to the environment after 120 h. Molecular mechanism of this adaptation involved amino acid metabolism and Na+-K+-ATPase ion transport. Meanwhile, energy metabolism and redox metabolism were critical to the adaptation to a sudden decrease in salinity. This study, for the first time at the protein level, revealed the molecular mechanisms underlying salinity adaption of S. paramamosain and provides theoretical guidelines for the cultivation of S. paramamosain and other marine crustaceans.