Shotgun analysis to identify differences in protein expression between granulocytes and hyalinocytes of the European flat oyster Ostrea edulis

Bivalve Haemocyte Subpopulations: A Review

“…Previous studies have shown that defensins and mytilins are stored mainly in granulocytes (272,273). Myticin C was found expressed in granulocytes of mussels M. galloprovincialis (274); on the contrary, Myticin C was identified expressed in hyalinocytes and not in granulocytes in the oyster O. edulis (238). Haemolymph cells exhibited distinct inter-specific lectin binding in clams (275), marine mussels (101,102,276) and freshwater mussels (132), suggesting that haemocytes subpopulations may express different sugar moieties and perform disparate functions.…”

“…Initially, the distinction between hyalinocytes and granulocytes was made based on morphological parameters, years later it has been confirmed that there are also functional differences between both haemolymph cell types after analysis of metabolic and functional parameters (122,221). Recently, research efforts are focusing on revealing dissimilar immune functions among marine invertebrate haemocyte subpopulations, for example in ascidians (222); crustaceans as shrimps (223)(224)(225)(226)(227)(228), lobsters (229) and crabs (230); gastropod molluscs as sea snails (231)(232)(233)(234), abalones (235) and sea hares (236); and bivalve molluscs as oysters (182,216,237,238). This review focuses on the major findings in functional differences between the main bivalve haemocyte types.…”

“…In the mussel M. galloprovincialis, although both haemocytes subpopulations were susceptible to UV light treatment, the damages induced in hyalinocytes were detected earlier than in granulocytes, which led authors to suggest that the cytoplasmic granules of granulocytes could have some protective effect against apoptosis induced by UV radiation (269). On the contrary, in the oyster O. edulis, granulocytes appeared more affected by apoptosis than hyalinocytes (270); after a proteomic approach more proteins related with apoptosis were identified in granulocytes (237,238). In the clam R. decussatus, haemocytes stimulation with lipopolysaccharide induced a significant upregulation of a gene with important roles in the apoptotic process, with a maximum level registered in granulocytes (73).…”

“…Oyster C. virginica galectins CvGal1 and CvGal2 and clam R. philippinarum galectin MaGal1 were identified with strong ability to recognise parasites of the genus Perkinsus (277-279); one of them, CvGal1, has been observed to be secreted by granulocytes (277). In oysters O. edulis, the lectins galectin-4 isoform X1 and ß-1,4-N-acetylgalactosaminyltransferase bre-4like appear to be expressed in hyalinocytes (238). Lectin-like receptors (LLRs) were found to play important roles in the phagocytosis of granulocytes and semigranulocytes in C. gigas (280).…”

“…In the same species, dopamine b-hydroxylase (DBH), a norepinephrine synthesising enzyme, was highly expressed in granulocytes and involved in neuroendocrine and immune response (290). Differences in the expression of neuroendocrine immunomodulation (NEI) related proteins between oyster O. edulis haemocyte types have been detected (238). Some antigens reacted differently in granulocytes and agranulocytes in the deep-sea symbiotic mussel B. japonicus (291).…”