L-3,4-DIHYDROXYPHENYLALANINE (L-DOPA) SECRETED BY OYSTER (CRASSOSTREA-GIGAS) MANTLE CELLS - FUNCTIONAL-ASPECTS

L-DOPA is present in many molluscan periostraca and is thought to play an important role in the shell protein sclerotization mechanism. We a nalyzed L-DOPA content in organic membranes produced by the oyster (Cr assostrea gigas) mantle as a reaction against shell damage, such as in duced by Polydora sp. infestation, an artificial perforation of the sh ell, and in normal oysters mantle. When oysters are secreting the prot ective organic membrane against a shell perforation, the area of mantl e close to the repairing region had a greater L-DOPA content than the remaining mantle. Mantle border as a whole had the same L-DOPA content as the central mantle. Nevertheless there is a variation pattern in m antle border L-DOPA content, the area near the umbo having a higher co ntent and decreasing towards the frontal region. L-DOPA content in you nger oysters was greater than that in older oysters. The results of pe rforation experiment suggest a good correlation between organic membra ne synthesis and L-DOPA mantle border content. Concerning normal oyste rs, a higher L-DOPA content in mantle border than in central mantle wo uld be expected but we couldn't detect any differences. From all the r esults there is some evidence that mantle L-DOPA is related to other f unctions in addition to participating in the sclerotization mechanism. (C) 1998 Elsevier Science Inc. Al! rights reserved.