Mj. Almeida et al., L-3,4-DIHYDROXYPHENYLALANINE (L-DOPA) SECRETED BY OYSTER (CRASSOSTREA-GIGAS) MANTLE CELLS - FUNCTIONAL-ASPECTS, Comparative biochemistry and physiology. B. Comparative biochemistry, 120(4), 1998, pp. 709-713
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.