Molecular markers for hemocyte subpopulations in crayfish Cherax quadricarinatus

Semigranular cells (SGCs) and granular cells (GCs) are two dominant groups of circulating hemocytes in crayfish Cherax quadricarinatus. Molecular markers are required for the clear classification of the hemocytes and the research of their function and differentiation. In this study, we compared the protein content of GCs and SGCs by using two workflows: one-dimensional gel electrophoresis followed by LC-MS/MS and in-solution digestion of cell lysate followed by LC-MS/MS. Cell type-specific proteins were identified, and their expression in SGCs and GCs was further investigated by RT-PCR, Western blotting, and immunofluorescence analysis. Three molecular markers for GCs (peroxinectin, a mannose-binding protein, and prophenoloxidase-activating enzyme 2a) and three molecular markers for SGCs (a vitelline membrane outer layer protein I-like protein, a C-type lectin, and a peptidase) were identified. The application of some of the markers in Eriocheir sinensis was also analyzed. These molecular markers are useful tools for the research of crustaceans hemocytes.