Differential protein expression in haemolymph of first-stage red sternum mud crabs (Scylla serrata)

Abstract

Mud crab (Scylla serrata) is one of the important commercial aquatic animals in Thailand. A cause of death in crab farm is red sternum syndrome. The aim of this research was to characterize differential protein expression in the haemolymph of normal mud crabs and first-stage red sternum mud crabs using gel filtration chromatography on a Sephacryl S-200 chromatography column for protein purification. Results showed that the haemolymph of the red sternum mud crabs presented two fractions (F1 and F2) that were not found in that of the normal mud crabs. Subsequently, these peak fractions were separated by two-dimensional electrophoresis (2DE) technique. Each peak fraction was found to contain 1 spot. These protein spots were successfully identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Results indicated that F1 and F2 were alpha-2-macroglobulin (A2M), which was expressed in the haemolymph of the red sternum mud crabs but not in that of the normal mud crabs. Furthermore, the A2M plays important roles in innate defense of crustaceans. Our results may help understand the mechanism of molecular responses of mud crab to red sternum syndrome.