Research of the molecular mechanism in the wound-healing system of marine shellfish

点击翻译按钮获取中文摘要

Scallop hemocytes contain a transglutaminase (TGase) that is electrophoretically different from the TGase in the adductor muscle. When hemocyte homogenate was incubated with monodansylcadaverine (MDC) at 10℃, MDC was incorporated into the 230 kDa and 100 kDa proteins of the hemocytes. The 100 kDa protein was only detected in the supernatant, the 230 kDa protein was insoluble, and the 210 kDa protein was detected in both fractions. In the absence of MDC, the 230 kDa, 210 kDa, and 100 kDa proteins were cross-linked by endogenous transglutaminase. The 230 kDa protein was most quickly cross-linked and formed huge polymers within five minutes. The amino acid sequence of a BrCN-cleaved fragment derived from the 100 kDa protein showed the obvious homology to the conservative sequences of the other TGases, suggesting this component was the enzyme itself. Although the amino terminal region and six BrCN-cleaved fragments of the 230 kDa protein were sequenced, no significant homology to the known proteins was detected ; the 230 kDa protein was supposed to be a novel protein. The 210 kDa protein was only sequenced at the amino terminal eight residues of a BrCN-fragment. In this research, micro channel array flow analyzer (MC-FAN) was used for the first time to analyze the aggregation of shellfish hemocytes. The aggregation was stimulated in the presence of calcium ion and suppressed by EGTA, though an individual difference was comparatively large. Brackish water clam contained at least three TGase isozymes containing marine and fresh water-type enzymes, suggesting TGase could be active extracellularly rather than intracellularly. These results suggest that if scallop tissues are injured, hemocyte transglutaminase may be activated, initially cross-linking the insoluble hemocyte 230 kDa protein, followed by the 210 kDa proteins, to form a cross-linked protein matrix with inter cross-linking of hemocyte sheets, to stop the bleeding.