The Hemolymph Coagulation System of Shrimps

Abstract

The effects of different anticoagulants on the shrimp coagulation systems were studied. Metal ion chelators, Zn2+, Hg2+, serine protease inhibitors and some transglutaminase-inhibitors were found to inhibit the coagulation. We have purified the clottable proteins (CP) from the hemolymph of marine shrimps Penaeus monodon and Penaeus japonicus by DEAE-ion exchanger and gel-filtration. The purified CP was cross-linked to form an insoluble clot in vitro by the shrimp hemocyte transglutaminase (TG) in the presence of 10−4 M Ca2+. Being a dimer of 92 kDa subunits, the shrimp TG is homologous to Factor XIIIa of the mammalian coagulation system, but very unstable especially in presence of Ca2+. The soluble CP-dimers or oligomers are composed of glycoprotein subunits of 180 kDa, which contain 24% glucose and 9% Nacetylglucosamine. Its N-terminal amino acid sequence up to the 25th residue is LQPGLEYQYRYSARVASGIPSINRQ, bearing 72 and 28% similarity to the lobster CP and the C. elegans vitellogenin, respectively. Using the rabbit antiserum raised against the shrimp CP for western-blot analysis we found that the CP was present only in the hemolymph and hemopoietic nodule tissue but not in the midgut or the muscle of the shrimp. The rocket immunoelectrophoretic analyses showed specific changes of the hemolymph CP-concentration under different physiological conditions. The anti-CP antiserum also precipitated the CP’s in hemolymphs of other penaeid and metapenaeid shrimps but not those of lobster, fresh water prawn (Macrobrachium rosenbergii) or marine crab.