Changes in the electrophoretic profiles of gill mucus proteases of the Eastern oyster Crassostrea virginica in response to infection by the turbellarian Urastoma cyprinae

Urastoma cyprinae occurs on the gills of various bivalves species, includin g the eastern oyster Crassostrea virginica. While the worm is known to caus e severe gill disruption in mussels, no evidence of this nature has been de scribed for oysters. Nonetheless, high levels of U. cyprinae have been repo rted in oysters, which may, in turn, reduce the oyster's overall condition. U. cyprinae is strongly attracted to oyster gill mucus, which is suggested to play an active role in the worm's feeding activities. Furthermore, host mucus contains many active components, including proteases, which have bee n suggested to play a defensive role against invading organisms. It follows , therefore, that some of the interactions between U. cyprinae and oysters take place in host gill mucus. Studies were undertaken to determine whether the presence of U. cyprinae altered the electrophoretic profiles of oyster gill mucus, using proteases as indicators. Findings reveal that oyster gil l mucus contains three proteases, a putative acid protease at 96 kDa, a zin c metalloprotease at 64 kDa, and a serine protease at 33 kDa. Results based on experiments using mucus preparations extracted from infected and noninf ected oysters, along with those using lyophilized mucus incubated with live U. cyprinae, confirm that the presence of U. cyprinae alters the protease composition of gill mucus. The present data demonstrate that both U. cyprin ae and host gill mucus actively secrete proteases. While the precise roles of these enzymes still need to be defined, one of their functions may be as sociated with digestion-related activities induced by the worm. (C) 2000 Ac ademic Press.