Tissue-specific expression and regulation of the haemolymph clottable protein of tiger shrimp (Penaeus monodon)

The clottable protein (CP) involved in Penaeus monodon haemolymph coagulation has previously been characterized and cloned. Polyclonal antibodies against purified CP were also prepared from rabbit serum. By Western blot analyses, we showed occurrence of CP in the shrimp central nervous system, gill, and lymphoid organ. Results of RT-PCR further indicated that the central nervous system, gill, and lymphoid organ transcribed more CP, heart and hepatopancreas transcribed less, while the haemocytes and the muscle did not. We further analyzed the CP distribution within shrimp lymphoid organ by immunohistochemical method, CP was found to localise in stromal cells of lymphoid organ rather than in the developing haemocytes. In addition, concentrations and regulation of the plasma CP under normal and artificially traumatic conditions were studied with rocket immunoelectrophoresis. The average plasma CP concentration in normal intermolt shrimps was elevated from 3 mg ml−1 to above 12 mg ml−1 after successive blood-withdrawing for a week. The production and secretion of CP apparently were increased more than 4 folds to compensate its loss. Our result also suggested that the shrimp sinus gland endocrine system is not directly required for the expression and up-regulation of CP.